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Synthesis and characterization of poly(vinylalcohol)-acid salt polymer electrolytesReda Khalil1 2lowast Eslam Sheha2 Taha Hanafy1dagger and Omar Al-Hartomy1
1Physics Department Faculty of Science Tabuk University 71421 KSA2Physics Department Faculty of Science Benha University Benha 13518 Egypt
ABSTRACT
A solid acid membranes based on poly(vinyl alcohol) (PVA) magnesium bromide (MgBr2) and phosphoricacid (H3PO4) were prepared by a solution casting method The morphological X-ray and electrical propertiesof the (PVA)(1minusx)(MgBr2)x2(H3PO4)x2 solid acid membranes where x = 00 01 02 03 and 04 wt wereinvestigated The PVA polymer electrolyte directly blended with acid salt shows improvement in ionic conduc-tivity and transport properties The maximum ionic conductivity value of PVAacid salt polymer electrolyte withx = 040 wt of acid salt is around 164times 10minus4 S cmminus1 at 20 C and the ionic transport number (t+) is inthe range of 098ndash099 In this work the data shows that the (PVA)(1minusx) (MgBr2)x2 (H3PO4)x2 solid acid saltmembrane is promising for intermediate temperature phosphoric acid fuel cell applications
1 INTRODUCTIONIn recent times extensive investigations on solid poly-mer electrolytes (SPE) have been in progress in viewof their potential applications in solid state electrochem-ical cells1ndash3 The solid polymer electrolytes (SPE) havebecome the area of wide variety of fundamental and tech-nological applications such as solid state batteries fuelcells double layer capacitors sensors electrochemical dis-play devices etc4ndash8 The one of the important com-ponents in rechargeable batteries and fuel cells devicesis the ionic conductor (electrolyte) Due to some spe-cial properties like good mechanical simple preparationin different forms good electrodendashelectrolyte contact andadhesive properties9 solid polymer electrolytes (SPEs)have emerged as important ionic conducting materialsOne of the attracted polymer electrolyte is proton con-ducting polymer due to their promising application in
lowastAuthor to whom correspondence should be addressedEmails rkhalilfscbuedueg redakhalil67gmailcom
daggerPresent address Physics Department Faculty of Science FayoumUniversity El Fayoum Egypt
battery and fuel cells Most proton-conducting polymersdepend on their water content which limits their applica-tion In order to overcome those limitations a number ofstudies have been performed to produce novel polymer-based materials that can transport protons under anhydrousconditions In this context phosphoric acid based systemsare widely studied for that because of its extensive self-ionization and low acid dissociation constant pKa PVAwas used as host polymers that keep phosphoric acid intheir matrix and proton transport is mainly provided byphosphoric acid units via structure diffusion where thetransference number of proton is close to unity1011
Although several homogeneous polymer electrolyteswere reported in earlier studies12ndash15 phosphoricacid doped polybenzimidazole (PBI) showed betterphysicochemical properties and promising fuel cellperformance16ndash20 Although high proton conductivity canonly be achieved at higher acid compositions dopantexclusion is an important drawback during prolongedusage in fuel cells Therefore our work has been drivenby a desire to develop a radically new alternative proton-conducting electrolyte (or membrane) that is based on
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Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
compounds whose chemistry and properties are interme-diate between those of a normal acid such as H3PO4 anda normal salt such as NaBr2 and not a hydrated polymer(solid acid) Thus membranes will be developed in whicha solid acid salt is embedded in PVA matrix with thepolymer providing mechanical support and enhancingchemical stability In this study an attempt has beenmade to prepare the polymer electrolytes based on PVAcomplexed with MgBr2H3PO4 at different concentrationsexpect to use it in fuel cell application Another approachto the development of proton-conducting membranes isto combine the functions of the Hydroquinone (HQ) andthe proton solvent in a single molecule Such moleculesmust be amphoteric in the sense that they behave as botha proton donor (acid) and proton acceptor (base) and theymust form dynamical hydrogen bonds Also HQ plays amajor role as a reducing agent for bromine and improvingthe chemical stability of the matrix In similar study theresults of addition of HQ to (PVA)07 lithium bromide(LiBr)03 sulfuric acid (H2SO429 and 2 (wv) ethylenecarbonate revealed that the thermal stability and electricalconductivity of the samples improve on increasing the HQdoping The film doped with 4 wt HQ exhibits maxi-mum conductivity was found to be 175times 10minus3 Scm atroom temperature21 In the present work 04 (wv) HQand 2 (wv) ethylene carbonate which used as plasticizerwere added to (PVA)1minusx(MgBr2x2(H3PO4x2 membraneto improve the thermal and structural properties Upon theabove considerations an attempt has been made to syn-thesis a broad range of (PVA)1minusx(MgBr2x2(H3PO4x2polymer composite and conductivity measurements sur-face morphologies and structure of the membranes wereinvestigated Effects of acid salt contents on protonconductivity of final product were discussed
2 EXPERIMENTAL DETAILS21 Preparation of PVAAcid Salt Polymer
ElectrolytesPoly(vinyl alcohol) PVA (degree of hydrolizationge 98Mw = 72000) magnesium bromide MgBr2 and phospho-ric acid (H3PO4 were received from Sigma The complexelectrolytes were prepared by mixing of 04 (wv) hhy-droquinone 1 (wv) ethylene carbonate PVA MgBr2 andH3PO4 at several stoichiometric ratios in distilled water toget PVA1minusx(MgBr2x2(H3PO4x2 complex electrolyteswhere x is 00 01 02 03 and 04 Wt Solution withvariable ratio was stirred vigorously and casted in Petridish following solution cast technique at room tempera-ture Five different polymer electrolytes were produced
22 Crystal Structure and Morphology AnalysisThe crystalline structures of all the PVA1minusx(MgBr2x2(H3PO4x2 composite polymer membranes were examinedusing a Philips XrsquoPert X-ray diffractometer (XRD) with
a Cu K radiation of wavelength k = 154056 Aring for 2angles between 4 and 60The cross-sectional view and top surface morphologies
and microstructures of all the complex electrolytes wereexamined with a S-2600H scanning electron microscope(Hitachi Co Ltd)
23 Ionic Conductivity and Transport PropertiesConductivity measurements were made forPVA1minusx(MgBr2x2(H3PO4x2 composite polymer mem-brane by an ac impedance method Samples of diameter05 cm were sandwiched between the two similar brasselectrodes of a spring-loaded sample holder The wholeassembly was placed in a furnace monitored by a temper-ature controller The rate of heating was adjusted to be2 Kmin Ionic and electronic transport numbers (tion telewere evaluated using Wagnerrsquos polarization techniqueImpedance measurements were carried out in the temper-ature range 303ndash423 K using Hioki 3532 programmableautomatic LCR meter The measurements were carried outover a frequency range 100 Hzndash100 kHz
3 RESULTS AND DISCUSSION31 Crystalline Structure and Surface MorphologyThe X-ray diffraction measurement was performed toexamine the nature of the crystallinity of the PVAacidsalt polymer electrolyte film Figure 1 shows the diffrac-tion pattern for the PVA polymer film and the compositePVAacid salt polymer electrolyte film It is well knownthat the PVA polymer film exhibits a semi-crystalline struc-ture with peak at a 2 angle of 20 As can be seen clearlyin Figure 1 a large peak at 2 of 20 for the PVA polymerfilm was seen But it was also clearly seen that the peakintensity of the PVAacid salt polymer electrolyte greatlyreduced when the acid salt was added This implies that the
0 10 20 30 40 50 60 70 80
2θ (degree)
I (a
u)
a
b
c
d
e
Fig 1 The X-ray diffraction patterns of PVA1minusx(MgBr2x2(PWA)x2acid salt polymer electrolyte with (a) x = 00 (b) x = 01 (c) x = 02(d) x = 03 and (e) x = 04
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Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
addition of acid salt into PVA polymer matrix greatly aug-mented the domain of amorphous region (ie XRD crystalpeak reduces) This indicates that the PVAacid salt poly-mer electrolyte film becomes much amorphous Notice thatthe degree of amorphous increases with increasing the con-tents of acid salt There is a significant motion of polymerchain in the amorphous phase or some defects while non-conducting in the crystalline phase The characteristic ofthe PVAacid salt polymer electrolyte film shows excellentionic conductivity property This is due to the more free-volume and flexible of local PVA chain segmental motionin the PVAacid salt polymer electrolyte22ndash24
The morphology of the free acid salt polymer electrolyte(x = 0) and composite PVAacid salt polymer electrolytefilm (with 0 ge x gt 04) has been examined by SEM andthe images are shown in Figure 2 The free acid salt poly-mer electrolyte film is observed to have uniform a homo-geneous and dense material Figure 2(a) The small amountof acid salt (x= 01) composite polymer electrolyte film isobserved to have uniform small pores at microscopic levelFigure 2(b) In the composite acid salt polymer electrolyte(x = 02) slightly larger in size and uniformly distributedpores are observed Figure 2(c) The uniformly dispersedpores in the polymer microstructure lead to the retentionof liquid electrolyte and formation of their better connec-tivity through the polymer giving rise to have possibilityof high ionic conductivity
32 Transference Number MeasurementThe transference numbers corresponding to ionic (tionand electronic (tele transport have been calculated for
Fig 2 The SEM micrograph for the surface ofPVA1minusx(MgBr2x2(H3PO4x2 solid acid salt polymer electrolyte with(a) x = 00 (b) x = 01 (c) x = 02 and (d) x = 03
all compositions of PVAacid salt polymer electrolytesystems using dc polarization method In this methodthe dc current is monitored as a function of time onthe application of fixed dc voltage (15 V) across thesample with copper blocking electrodes When acid saltincreases the pores size increases (Fig 2(d)) Figure 3shows the result of dc polarization measurements at 30 Cfor (PVA)06(MgBr202(H3PO402 membrane The transfer-ence numbers have been calculated from the polarizationcurrent versus time plot using the standard equation25
tion =Iiminus If
Ii(1)
where Ii is the initial current and If is the final resid-ual current The ionic transference number (tion) for thecomposition of the (x = 40 wt) electrolyte systems liesbetween 093 and 096 This suggests that the charge trans-port in these electrolyte films is predominantly ions
33 Temperature Dependence of Ionic ConductivityImpedance spectroscopy Figures 4(a) (b) shows the ColendashCole plots of Zprime versus Zprimeprime (where Zprime and Zprimeprime are the realand imaginary parts of the complex impedance respec-tively) of pure PVA and various compositions of com-plexed films with acid salt at different temperatures anddifferent frequencies These plots are single semicirculararcs with their centrersquos laying below the real axis at anangle The finite value of distribution parameter anda depressed arc are typical for a material with multirelax-ation processes26 Also the arcs have a non-zero inter-section with the real axis in the high frequency regionFurther there occurs a reduction in the size of these plotswith rise in temperature and acid salt contents The semi-circle represents the bulk conductivity which is due to the
Fig 3 Polarization current as a function of time for x= 04 PVAacidsalt polymer electrolyte
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Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
(a)
(b)
Fig 4 Complex impedance plots of PVA1minusx(MgBr2x2(PWA)x2acid salt polymer electrolyte (a) different acid salt concentration at303 K and (b) different temperatures (x = 01)
parallel combination of bulk resistance and bulk capaci-tance of the polymer electrolytes Considering the equiva-lent circuit model the values of Zprime and Zprimeprime are given by
Zprime = Rs +Rp
1+2C2pR
2p
and Zprimeprime = minusCpR2p
1+2C2pR
2p
(2)
where Rs Rp and Cp are the series resistor parallel resis-tor and parallel capacitor respectively Where = 2f isthe angular frequencyThese equations predict that the values of Zprime and Zprimeprime
should decrease with increasing temperature as the valuesof Rp and Rs go on decreasing with rise in temperature inaccordance with equation C = Cp+12R2
pC2p
This causes shrinking of the ColendashCole plots withincrease in temperature and acid salt contentsSingh et al27 have studied the relaxation characteristics
of PVA-H3PO4 and PVA-H2SO4 complex electrolytes inthe form of thin films samples and observed the impedancespectra as depressed single semicircular arcs for differentsamples corresponding to their two types of relaxation pro-cesses which are interpreted in terms of dipole-segmental
motion (-relaxation) and side chain dipole group motion(-relaxation) These results suggest that the migrationof charges (ions) may occur through the free volume ofmatrix polymer which can be represented by a resis-tor On the other hand non-migration charges (chains ofpolymer) polarized and can be therefore represented by acapacitor The decrease in resistance of the polymer elec-trolyte is due to the enhancement of the ionic mobility andthe number of carrier ions with acid salt concentration andtemperature28
The bulk electrical resistance (Rb of the material isobtained from the ColendashCole plots with the intercept of thehigh frequency side on the X-axis Analysis of the spec-tra yields information about the properties of the PVAacidsalt polymer electrolyte such as bulk resistance Rb Tak-ing into account the thickness of the PVAacid salt elec-trolyte films the Rb value was converted into the ionicconductivity value according to the formula
= L
RbA(3)
where L is the thickness (cm) of the PVAacid salt polymerelectrolyte A the area of the blocking electrode (cm2) andRb is the bulk resistance ( of PVAacid salt polymerelectrolyteFigure 5 shows the ionic conductivity values for the
PVAacid salt polymer electrolytes with different contentsof acid salt It can be seen clearly that the ionic conductiv-ity of the PVAacid salt SPE can be significantly enhancedwhen the content of acid salt increasesFigure 6 represents the temperature dependence of ionic
conductivity for all compositions of PVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytes It has been found that theionic conductivity of the PVAacid salt SPE increases withincreasing temperature for all compositions indicating
Fig 5 The Influence of acid salt content on ionic conductivity ofPVA1minusx(MgBr2x2(H3PO4x2 solid acid salt polymer electrolyte
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Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
Fig 6 Arrhenius plot for PVA1minusx(MgBr2x2(H3PO4x2 solid acidsalt polymer electrolyte
Arrhenius type thermally activated process given by therelation
= o exp(minus Ea
RT
)(4)
where o is a pre-exponential factor Ea the activationenergy and T is the temperature in Kelvin This can beexplained on the basis of the free volume model29 andhopping of charge carriers between the localized states30
Since poly(vinyl alcohol) is a linear polymer with carbonchain as the back bone the polymer chains which are lessentangled are capable of causing electrical conductivityFurther PVA being a polar polymer ionizes the MgBr2
salt into anions and cations under the influence of theapplied electric field and temperature These ions hopbetween the localized states and cause enhanced con-ductivity Further when the temperature is increased thevibration energy of a segmental is sufficient to push againstthe hydrostatic pressure imposed by its neighboring atomsand create a small amount of space surrounding its ownvolume in which vibration motion can occur31 There-fore the free volume around the polymer chain causes themobility of ions and polymer segments and hence the con-ductivity The increment of temperature causes the increasein conductivity due to the increased free volume and theirrespective ionic and segmental mobility The amorphous
Table I Effect of the acid salt concentration on the activation energies(Ea and conduction index (n) values
nature also provides a bigger free volume in the poly-mer electrolytes system upon increasing temperature32
The ln versus 103T plots obtains the activation energy(Ea of the PVAacid salt SPE which is dependent on thecontents of acid salt in the polymer matrixIt has been found that the highest conductivity poly-
mer electrolyte (x = 04) has the lowest activation energy(038 eV) see Table I It is noteworthy that the poly-mer electrolytes with low values of activation energies aredesirable for practical applicationsFigure 7 shows the frequency-dependent conductiv-
ity of PVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytesThe plot shows two regions The first region observedat low frequency plateau region corresponds to the fre-quency independent conductivity (dc The second regionobserved at the high frequency dispersion region whichcorresponds to the conductivity increases with increasingfrequency This behavior obeys the universal power law13
tot= dc+An (5)
where dc is the dc conductivity (the extrapolation of theplateau region to zero frequency) A is the pre-exponentialfactor is the angular frequency and n the fractionalexponent which lies between 0 and 1 According to thejump relaxation model at low frequencies ions can jumpfrom one site to its neighboring site While at higher fre-quencies due to the short time periods the probability forions to go back to their initial sites increases which causesincrease in the conductivity3334 The values of the expo-nent n have been obtained using the least square fitting ofEq (5) it can be observed that the exponent n decreaseswith increasing concentration of the acid salt see Table IThis behavior can be interpreted in light of the fact thatdoping of acid salt increases the number of chain segmentsthat are responsive to the external electric field frequencyThe study of dielectric relaxation in solid polymer elec-
trolytes is a powerful approach for obtaining information
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Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
about the characteristics of ionic and molecular interac-tions The dielectric parameters associated with relaxationprocesses are of particular significance in ion conductingpolymers where the dielectric constant plays a fundamen-tal role which shows the ability of a polymer material todissolve saltsThe dielectric constant was used as an indicator to
show that the increase in conductivity is mainly due to anincrease in the number density of mobile ions35 The rela-tionship between complex impedance dielectric permit-tivity and dielectric loss can be shown in the followingformulae prime = CpLoA primeprime = o where prime
denotes the real part of dielectric function primeprime as theimaginary part of dielectric function or dielectric loss ando as the permittivity of the free space Figures 8(a)(b) shows the variation of the dielectric permittivity prime
and dielectric loss primeprime for PVA1minusx(MgBr2x2 (H3PO4x2polymer electrolytes versus frequency at room tempera-ture 30 C The figure show that prime and primeprime a graduallydecrease with increasing frequency for all prepared sam-ples The decrease of prime and primeprime with frequency can beassociated to the inability of dipoles to rotate rapidly lead-ing to a lag between frequency of oscillating dipole and
Fig 8 Frequency dependence of (a) Dielectric constant prime and(b) dielectric loss primeprime for PVA1minusx(MgBr2x2(H3PO4x2 solid acid saltpolymer electrolyte
that of applied field The variation indicates that at low fre-quencies the dielectric constant is high due to the interfa-cial polarization and the dielectric loss (primeprime) becomes verylarge at lower frequencies due to free charge motion withinthe material36
This behavior can be described by the Debye dispersionrelation37
prime + s minus1+2132
primeprime s minus131+2132
(6)
where and s are the static and infinite dielectric per-mittivity 13 is the relaxation time and is the angularfrequencyFigures 9(a)ndash(b) show the variation of dielec-
tric permittivity prime and dielectric loss primeprime forPVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytes withtemperature at 1 kHz The value of prime and primeprime increaseswith temperature The observed increase in of prime anddielectric loss primeprime with temperature could be attributed todecrease in the viscosity of the polymeric material Thisleads to an increment in the degree of dipole orientationof polar dielectric material and hence dielectric constant
Fig 9 Temperature dependence of (a) Dielectric constant prime and(b) dielectric loss primeprime for PVA1minusx(MgBr2x2(H3PO4x2 solid acid saltpolymer electrolyte
488 Mater Express Vol 4 2014
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Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
increases38 Dipolar molecules should be able to orientfrom one equilibrium position to another relatively easilyand contribute to absorption39
4 CONCLUSIONPVAacid salt polymer electrolytes with a different com-position were obtained by a solution casting method Thephyso-chemiacal characteristic properties of the compositeare systematically studied by using a XRD SEM and ACimpedance method The XRD study reveals the amorphousnature of the polymer-acid salt complexes that produceshigh ionic diffusivity The introduction of acid salt to thePVA polymer electrolytes has proved to be a convenientmethod to increase the ionic conductivity at ambient tem-perature Addition of acid salt causes an enhancement inits mobility and charge carrier concentration The ionictransference number of mobile ions has been estimated tobe in the range 093 and 096 revealing that the conductingspecies are predominantly due to ions The temperaturedependence of conductivity of PVAacid salt obeys Arrhe-nius relation in the temperature range studied In fact theionic conductivity value greatly depends on the acid saltcontents in the PVA polymer electrolyte These compositePVAacid salt polymer electrolytes show a highly potentialfor applications on fuel cell systems
Acknowledgment The financial supported for thisstudy from the University of Tabuk Saudi Arabia underthe project No 21211432H are gratefully acknowledged
References and Notes1 J Lee Y Lee W Chae and Y Sung Enhanced ionic conductiv-
ity in PEO-LiClO4 hybrid electrolytes by structural modificationJ Electroceram 17 941 (2006)
2 M Sundar and S Selladurai Effect of fillers on Magnesium-poly(ethylene oxide) solid polymer electrolyte Ionics 12 281 (2006)
3 V Subba Reddy Ch A P Jin Q Y Zhu L Q Mai and W ChenPreparation and characterization of (PVP+NaClO4 electrolytes forbattery applications Eur Phys J E Soft Matter 19 471 (2006)
4 M B Armand Polymer electrolytes Ann Rev Mater Sci 16 245(1986)
5 J R MacCullum and C A Vincent Polymer Electrolytes ReviewsElsevier Applied Science Publisher London (1987) and (1989)Vols 1ndash2
6 D E Fenton J M Parker and P V Wright Complexes of alkalimetal ions with poly(ethylene oxide) Polymer 14 589 (1973)
7 C W Walker Jr and M Salomon Improvement of ionic conductivityin plasticized PEO-based solid polymer electrolytes J ElectrochemSoc 140 3409 (1993)
8 C A Finch Polyvinylalcohol Wiley Interscience Pub New York(1973)
9 F Ahmad and E Sheha Preparation and physical properties of(PVA)07 (NaBr)03(H3PO4xM solid acid membrane for phosphoricacidmdashFuel cells J Advanced Research 4 155 (2013)
10 T Dippel K D Kreuer J C Lassegravegues and D Rodriguez Protonconductivity in fused phosphoric acid A 1H31P PFG-NMR and QNSstudy Solid State Ionics 61 41 (1993)
11 S Uuml Ccedilelik A Aslan and A Bozkurt Phosphoric acid-dopedpoly(1-vinyl-124-triazole) as water-free proton conducting polymerelectrolytes Solid State Ionics 179 683 (2008)
12 P Donoso W Gorecki C Berthier F Defendini C Poinsignon andM B Armand NMR conductivity and neutron scattering investiga-tion of ionic dynamics in the anhydrous polymer protonic conductorPEO(H3PO4x Solid State Ionics 28ndash30 969 (1988)
13 E Sheha Preparation and physical properties of(PVA)075(NH4Br)025(H2SO4xM solid acid membrane Journal ofNon-Crystalline Solids 356 2282 (2010)
14 A Aslan S Uuml Ccedilelik and A Bozkurt Proton-conducting proper-ties of the membranes based on poly(vinyl phosphonic acid) graftedpoly(glycidyl methacrylate) Solid State Ionics 180 1240 (2009)
15 M F Daniel B Desbat F Cruege O Trinquet and J C LasseguesSolid state protonic conductors Poly(ethyleneimine) sulfates andphosphates Solid State Ionics 28ndash30 637 (1988)
16 R Tanaka H Yamamoto A Shono K Kubo and M SakuraiProton conducting behavior in non-crosslinked and crosslinkedpolyethylenimine with excess phosphoric acid Electrochim Acta45 1385 (2000)
17 S R Samms S Wasmus and R F Savinell Thermal stability ofproton conducting acid doped Polybenzimidazole in simulated fuelcell Environments J Electrochem Soc 143 1225 (1996)
18 Q Li R He J-A Gao J O Jensen and N J Bjerrum The CO poi-soning effect in PEMFCs operational at temperatures up to 200 CJ Electrochem Soc 150 A1599 (2003)
19 H Pu W H Meyer and G Wegner Proton transport in polybenz-imidazole blended with H3PO4 or H2SO4 J Polymer Sci B PolymerPhys 40 663 (2002)
20 Y Zhai H Zhang Y Zhang and D Xing A novel H3PO4NafionndashPBI composite membrane for enhanced durability of high tempera-ture PEM fuel cells J Power Source 169 259 (2007)
21 B Samy and E Sheha Impact of hydroquinone on thermal andelectrical properties of plasticized [poly(vinylalcohol)]07 (LiBr)03-(H2SO4
minus125 molL solid acid membrane Polymer Int 60 1142 (2011)
22 A Hassen T Hanafy S El Sayed and A Himanshu Dielectricrelaxation and alternating current conductivity of polyvinylidene flu-oride doped with lanthanum chloride J Appl Physics 110 114(2011)
23 S Mahrous and T Hanafy Dielectric analysis of chlorinatedpolyvinyl chloride stabilized with di-n-octyltin maleate J AppliedPolymer Science 113 316 (2009)
24 B Wagner and C Wagner Electrical conductivity measurements oncuprous halides J Chem Phys 26 1597 (1957)
25 M Hema S Selvasekerapandian A Sakunthala D Arunkumarand H Nithy Structural vibrational and electrical characterizationof PVAndashNH4Br polymer electrolyte system Physica B 403 2740(2008)
26 E Barsoukov and J Ross Macdonald Impedance SpectroscopyTheory Experiment and Applications-Wiley-Interscience (2005)
27 K P Singh and P N Gupta Study of dielectric relaxation in polymerelectrolytes Eur Polym J 34 1023 (1998)
28 R Baskaran S Selvasekharapandian H Kumar andG Bhuvaneswari Dielectric and conductivity relaxations in PVAcbased Ionics 10 129 (2004)
29 J R Chetia M Maullick A Dutta and N N Dass Role of poly(2-dimethylaminoethylmethacerylate) salt as solid state ionics MaterSci Eng B 107 134 (2004)
30 P K C Pillai P Khurana and A Trilateral Dielectric studies ofpoly(methyl methacrylate)polystyrene double layer system J MatSci Lett 5 629 (1986)
31 M S Michael M E Jacob S Prabaharan and S RadhakrishnaEnhanced lithium ion transport in PEO-based solid polymer elec-trolytes employing a novel class of plasticizers Solid State Ionics98 167 (1997)
32 A K Jonscher The lsquouniversalrsquo dielectric response Nature 267 673(1977)
33 M Ahmad S H Sabeeh and S A Hussen Electrical and opticalproperties of PVALiI polymer electrolyte films Asian Transactionson Science amp Technology 1 16 (2012)
Mater Express Vol 4 2014 489
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Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
34 E Sheha and M K El-Mansy A high voltage magnesium batterybased on H2SO4-doped (PVA)07(NaBr)03 solid polymer electrolyteJ Power Sources 185 1509 (2008)
35 S R Majid and A K Arof Electrical behavior of proton-conductingchitosan-phosphoric acid-based electrolytes Physica B 390 209(2007)
36 A Kyritsis P Pissis and J Grammatikakis Dielectric relax-ation spectroscopy in poly(hydroxyethyl acrylates)water hydrogelsJ Polymer Sci Part B Polymer Phys 33 1737 (1995)
37 E Nora Dielectric Properties and Molecular Behavior Series inPhysical Chemistry Publishers Van Nostrand (1969)
38 G K Prajapati R Roshan and P N Gupta Effect of plasticizeron ionic transport and dielectric properties of PVAndashH3PO4 protonconducting polymeric electrolytes J Phys Chem Solids 71 1717(2010)
39 E Sheha Ionic conductivity and dielectric properties of plasticizedPVA07(LiBr)03(H2SO427 M solid acid membrane and its perfor-mance in a magnesium battery Solid State Ionics 180 1575 (2009)
Received 1 July 2014 RevisedAccepted 24 August 2014
490 Mater Express Vol 4 2014
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Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
compounds whose chemistry and properties are interme-diate between those of a normal acid such as H3PO4 anda normal salt such as NaBr2 and not a hydrated polymer(solid acid) Thus membranes will be developed in whicha solid acid salt is embedded in PVA matrix with thepolymer providing mechanical support and enhancingchemical stability In this study an attempt has beenmade to prepare the polymer electrolytes based on PVAcomplexed with MgBr2H3PO4 at different concentrationsexpect to use it in fuel cell application Another approachto the development of proton-conducting membranes isto combine the functions of the Hydroquinone (HQ) andthe proton solvent in a single molecule Such moleculesmust be amphoteric in the sense that they behave as botha proton donor (acid) and proton acceptor (base) and theymust form dynamical hydrogen bonds Also HQ plays amajor role as a reducing agent for bromine and improvingthe chemical stability of the matrix In similar study theresults of addition of HQ to (PVA)07 lithium bromide(LiBr)03 sulfuric acid (H2SO429 and 2 (wv) ethylenecarbonate revealed that the thermal stability and electricalconductivity of the samples improve on increasing the HQdoping The film doped with 4 wt HQ exhibits maxi-mum conductivity was found to be 175times 10minus3 Scm atroom temperature21 In the present work 04 (wv) HQand 2 (wv) ethylene carbonate which used as plasticizerwere added to (PVA)1minusx(MgBr2x2(H3PO4x2 membraneto improve the thermal and structural properties Upon theabove considerations an attempt has been made to syn-thesis a broad range of (PVA)1minusx(MgBr2x2(H3PO4x2polymer composite and conductivity measurements sur-face morphologies and structure of the membranes wereinvestigated Effects of acid salt contents on protonconductivity of final product were discussed
2 EXPERIMENTAL DETAILS21 Preparation of PVAAcid Salt Polymer
ElectrolytesPoly(vinyl alcohol) PVA (degree of hydrolizationge 98Mw = 72000) magnesium bromide MgBr2 and phospho-ric acid (H3PO4 were received from Sigma The complexelectrolytes were prepared by mixing of 04 (wv) hhy-droquinone 1 (wv) ethylene carbonate PVA MgBr2 andH3PO4 at several stoichiometric ratios in distilled water toget PVA1minusx(MgBr2x2(H3PO4x2 complex electrolyteswhere x is 00 01 02 03 and 04 Wt Solution withvariable ratio was stirred vigorously and casted in Petridish following solution cast technique at room tempera-ture Five different polymer electrolytes were produced
22 Crystal Structure and Morphology AnalysisThe crystalline structures of all the PVA1minusx(MgBr2x2(H3PO4x2 composite polymer membranes were examinedusing a Philips XrsquoPert X-ray diffractometer (XRD) with
a Cu K radiation of wavelength k = 154056 Aring for 2angles between 4 and 60The cross-sectional view and top surface morphologies
and microstructures of all the complex electrolytes wereexamined with a S-2600H scanning electron microscope(Hitachi Co Ltd)
23 Ionic Conductivity and Transport PropertiesConductivity measurements were made forPVA1minusx(MgBr2x2(H3PO4x2 composite polymer mem-brane by an ac impedance method Samples of diameter05 cm were sandwiched between the two similar brasselectrodes of a spring-loaded sample holder The wholeassembly was placed in a furnace monitored by a temper-ature controller The rate of heating was adjusted to be2 Kmin Ionic and electronic transport numbers (tion telewere evaluated using Wagnerrsquos polarization techniqueImpedance measurements were carried out in the temper-ature range 303ndash423 K using Hioki 3532 programmableautomatic LCR meter The measurements were carried outover a frequency range 100 Hzndash100 kHz
3 RESULTS AND DISCUSSION31 Crystalline Structure and Surface MorphologyThe X-ray diffraction measurement was performed toexamine the nature of the crystallinity of the PVAacidsalt polymer electrolyte film Figure 1 shows the diffrac-tion pattern for the PVA polymer film and the compositePVAacid salt polymer electrolyte film It is well knownthat the PVA polymer film exhibits a semi-crystalline struc-ture with peak at a 2 angle of 20 As can be seen clearlyin Figure 1 a large peak at 2 of 20 for the PVA polymerfilm was seen But it was also clearly seen that the peakintensity of the PVAacid salt polymer electrolyte greatlyreduced when the acid salt was added This implies that the
0 10 20 30 40 50 60 70 80
2θ (degree)
I (a
u)
a
b
c
d
e
Fig 1 The X-ray diffraction patterns of PVA1minusx(MgBr2x2(PWA)x2acid salt polymer electrolyte with (a) x = 00 (b) x = 01 (c) x = 02(d) x = 03 and (e) x = 04
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Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
addition of acid salt into PVA polymer matrix greatly aug-mented the domain of amorphous region (ie XRD crystalpeak reduces) This indicates that the PVAacid salt poly-mer electrolyte film becomes much amorphous Notice thatthe degree of amorphous increases with increasing the con-tents of acid salt There is a significant motion of polymerchain in the amorphous phase or some defects while non-conducting in the crystalline phase The characteristic ofthe PVAacid salt polymer electrolyte film shows excellentionic conductivity property This is due to the more free-volume and flexible of local PVA chain segmental motionin the PVAacid salt polymer electrolyte22ndash24
The morphology of the free acid salt polymer electrolyte(x = 0) and composite PVAacid salt polymer electrolytefilm (with 0 ge x gt 04) has been examined by SEM andthe images are shown in Figure 2 The free acid salt poly-mer electrolyte film is observed to have uniform a homo-geneous and dense material Figure 2(a) The small amountof acid salt (x= 01) composite polymer electrolyte film isobserved to have uniform small pores at microscopic levelFigure 2(b) In the composite acid salt polymer electrolyte(x = 02) slightly larger in size and uniformly distributedpores are observed Figure 2(c) The uniformly dispersedpores in the polymer microstructure lead to the retentionof liquid electrolyte and formation of their better connec-tivity through the polymer giving rise to have possibilityof high ionic conductivity
32 Transference Number MeasurementThe transference numbers corresponding to ionic (tionand electronic (tele transport have been calculated for
Fig 2 The SEM micrograph for the surface ofPVA1minusx(MgBr2x2(H3PO4x2 solid acid salt polymer electrolyte with(a) x = 00 (b) x = 01 (c) x = 02 and (d) x = 03
all compositions of PVAacid salt polymer electrolytesystems using dc polarization method In this methodthe dc current is monitored as a function of time onthe application of fixed dc voltage (15 V) across thesample with copper blocking electrodes When acid saltincreases the pores size increases (Fig 2(d)) Figure 3shows the result of dc polarization measurements at 30 Cfor (PVA)06(MgBr202(H3PO402 membrane The transfer-ence numbers have been calculated from the polarizationcurrent versus time plot using the standard equation25
tion =Iiminus If
Ii(1)
where Ii is the initial current and If is the final resid-ual current The ionic transference number (tion) for thecomposition of the (x = 40 wt) electrolyte systems liesbetween 093 and 096 This suggests that the charge trans-port in these electrolyte films is predominantly ions
33 Temperature Dependence of Ionic ConductivityImpedance spectroscopy Figures 4(a) (b) shows the ColendashCole plots of Zprime versus Zprimeprime (where Zprime and Zprimeprime are the realand imaginary parts of the complex impedance respec-tively) of pure PVA and various compositions of com-plexed films with acid salt at different temperatures anddifferent frequencies These plots are single semicirculararcs with their centrersquos laying below the real axis at anangle The finite value of distribution parameter anda depressed arc are typical for a material with multirelax-ation processes26 Also the arcs have a non-zero inter-section with the real axis in the high frequency regionFurther there occurs a reduction in the size of these plotswith rise in temperature and acid salt contents The semi-circle represents the bulk conductivity which is due to the
Fig 3 Polarization current as a function of time for x= 04 PVAacidsalt polymer electrolyte
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Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
(a)
(b)
Fig 4 Complex impedance plots of PVA1minusx(MgBr2x2(PWA)x2acid salt polymer electrolyte (a) different acid salt concentration at303 K and (b) different temperatures (x = 01)
parallel combination of bulk resistance and bulk capaci-tance of the polymer electrolytes Considering the equiva-lent circuit model the values of Zprime and Zprimeprime are given by
Zprime = Rs +Rp
1+2C2pR
2p
and Zprimeprime = minusCpR2p
1+2C2pR
2p
(2)
where Rs Rp and Cp are the series resistor parallel resis-tor and parallel capacitor respectively Where = 2f isthe angular frequencyThese equations predict that the values of Zprime and Zprimeprime
should decrease with increasing temperature as the valuesof Rp and Rs go on decreasing with rise in temperature inaccordance with equation C = Cp+12R2
pC2p
This causes shrinking of the ColendashCole plots withincrease in temperature and acid salt contentsSingh et al27 have studied the relaxation characteristics
of PVA-H3PO4 and PVA-H2SO4 complex electrolytes inthe form of thin films samples and observed the impedancespectra as depressed single semicircular arcs for differentsamples corresponding to their two types of relaxation pro-cesses which are interpreted in terms of dipole-segmental
motion (-relaxation) and side chain dipole group motion(-relaxation) These results suggest that the migrationof charges (ions) may occur through the free volume ofmatrix polymer which can be represented by a resis-tor On the other hand non-migration charges (chains ofpolymer) polarized and can be therefore represented by acapacitor The decrease in resistance of the polymer elec-trolyte is due to the enhancement of the ionic mobility andthe number of carrier ions with acid salt concentration andtemperature28
The bulk electrical resistance (Rb of the material isobtained from the ColendashCole plots with the intercept of thehigh frequency side on the X-axis Analysis of the spec-tra yields information about the properties of the PVAacidsalt polymer electrolyte such as bulk resistance Rb Tak-ing into account the thickness of the PVAacid salt elec-trolyte films the Rb value was converted into the ionicconductivity value according to the formula
= L
RbA(3)
where L is the thickness (cm) of the PVAacid salt polymerelectrolyte A the area of the blocking electrode (cm2) andRb is the bulk resistance ( of PVAacid salt polymerelectrolyteFigure 5 shows the ionic conductivity values for the
PVAacid salt polymer electrolytes with different contentsof acid salt It can be seen clearly that the ionic conductiv-ity of the PVAacid salt SPE can be significantly enhancedwhen the content of acid salt increasesFigure 6 represents the temperature dependence of ionic
conductivity for all compositions of PVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytes It has been found that theionic conductivity of the PVAacid salt SPE increases withincreasing temperature for all compositions indicating
Fig 5 The Influence of acid salt content on ionic conductivity ofPVA1minusx(MgBr2x2(H3PO4x2 solid acid salt polymer electrolyte
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Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
Fig 6 Arrhenius plot for PVA1minusx(MgBr2x2(H3PO4x2 solid acidsalt polymer electrolyte
Arrhenius type thermally activated process given by therelation
= o exp(minus Ea
RT
)(4)
where o is a pre-exponential factor Ea the activationenergy and T is the temperature in Kelvin This can beexplained on the basis of the free volume model29 andhopping of charge carriers between the localized states30
Since poly(vinyl alcohol) is a linear polymer with carbonchain as the back bone the polymer chains which are lessentangled are capable of causing electrical conductivityFurther PVA being a polar polymer ionizes the MgBr2
salt into anions and cations under the influence of theapplied electric field and temperature These ions hopbetween the localized states and cause enhanced con-ductivity Further when the temperature is increased thevibration energy of a segmental is sufficient to push againstthe hydrostatic pressure imposed by its neighboring atomsand create a small amount of space surrounding its ownvolume in which vibration motion can occur31 There-fore the free volume around the polymer chain causes themobility of ions and polymer segments and hence the con-ductivity The increment of temperature causes the increasein conductivity due to the increased free volume and theirrespective ionic and segmental mobility The amorphous
Table I Effect of the acid salt concentration on the activation energies(Ea and conduction index (n) values
nature also provides a bigger free volume in the poly-mer electrolytes system upon increasing temperature32
The ln versus 103T plots obtains the activation energy(Ea of the PVAacid salt SPE which is dependent on thecontents of acid salt in the polymer matrixIt has been found that the highest conductivity poly-
mer electrolyte (x = 04) has the lowest activation energy(038 eV) see Table I It is noteworthy that the poly-mer electrolytes with low values of activation energies aredesirable for practical applicationsFigure 7 shows the frequency-dependent conductiv-
ity of PVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytesThe plot shows two regions The first region observedat low frequency plateau region corresponds to the fre-quency independent conductivity (dc The second regionobserved at the high frequency dispersion region whichcorresponds to the conductivity increases with increasingfrequency This behavior obeys the universal power law13
tot= dc+An (5)
where dc is the dc conductivity (the extrapolation of theplateau region to zero frequency) A is the pre-exponentialfactor is the angular frequency and n the fractionalexponent which lies between 0 and 1 According to thejump relaxation model at low frequencies ions can jumpfrom one site to its neighboring site While at higher fre-quencies due to the short time periods the probability forions to go back to their initial sites increases which causesincrease in the conductivity3334 The values of the expo-nent n have been obtained using the least square fitting ofEq (5) it can be observed that the exponent n decreaseswith increasing concentration of the acid salt see Table IThis behavior can be interpreted in light of the fact thatdoping of acid salt increases the number of chain segmentsthat are responsive to the external electric field frequencyThe study of dielectric relaxation in solid polymer elec-
trolytes is a powerful approach for obtaining information
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Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
about the characteristics of ionic and molecular interac-tions The dielectric parameters associated with relaxationprocesses are of particular significance in ion conductingpolymers where the dielectric constant plays a fundamen-tal role which shows the ability of a polymer material todissolve saltsThe dielectric constant was used as an indicator to
show that the increase in conductivity is mainly due to anincrease in the number density of mobile ions35 The rela-tionship between complex impedance dielectric permit-tivity and dielectric loss can be shown in the followingformulae prime = CpLoA primeprime = o where prime
denotes the real part of dielectric function primeprime as theimaginary part of dielectric function or dielectric loss ando as the permittivity of the free space Figures 8(a)(b) shows the variation of the dielectric permittivity prime
and dielectric loss primeprime for PVA1minusx(MgBr2x2 (H3PO4x2polymer electrolytes versus frequency at room tempera-ture 30 C The figure show that prime and primeprime a graduallydecrease with increasing frequency for all prepared sam-ples The decrease of prime and primeprime with frequency can beassociated to the inability of dipoles to rotate rapidly lead-ing to a lag between frequency of oscillating dipole and
Fig 8 Frequency dependence of (a) Dielectric constant prime and(b) dielectric loss primeprime for PVA1minusx(MgBr2x2(H3PO4x2 solid acid saltpolymer electrolyte
that of applied field The variation indicates that at low fre-quencies the dielectric constant is high due to the interfa-cial polarization and the dielectric loss (primeprime) becomes verylarge at lower frequencies due to free charge motion withinthe material36
This behavior can be described by the Debye dispersionrelation37
prime + s minus1+2132
primeprime s minus131+2132
(6)
where and s are the static and infinite dielectric per-mittivity 13 is the relaxation time and is the angularfrequencyFigures 9(a)ndash(b) show the variation of dielec-
tric permittivity prime and dielectric loss primeprime forPVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytes withtemperature at 1 kHz The value of prime and primeprime increaseswith temperature The observed increase in of prime anddielectric loss primeprime with temperature could be attributed todecrease in the viscosity of the polymeric material Thisleads to an increment in the degree of dipole orientationof polar dielectric material and hence dielectric constant
Fig 9 Temperature dependence of (a) Dielectric constant prime and(b) dielectric loss primeprime for PVA1minusx(MgBr2x2(H3PO4x2 solid acid saltpolymer electrolyte
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Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
increases38 Dipolar molecules should be able to orientfrom one equilibrium position to another relatively easilyand contribute to absorption39
4 CONCLUSIONPVAacid salt polymer electrolytes with a different com-position were obtained by a solution casting method Thephyso-chemiacal characteristic properties of the compositeare systematically studied by using a XRD SEM and ACimpedance method The XRD study reveals the amorphousnature of the polymer-acid salt complexes that produceshigh ionic diffusivity The introduction of acid salt to thePVA polymer electrolytes has proved to be a convenientmethod to increase the ionic conductivity at ambient tem-perature Addition of acid salt causes an enhancement inits mobility and charge carrier concentration The ionictransference number of mobile ions has been estimated tobe in the range 093 and 096 revealing that the conductingspecies are predominantly due to ions The temperaturedependence of conductivity of PVAacid salt obeys Arrhe-nius relation in the temperature range studied In fact theionic conductivity value greatly depends on the acid saltcontents in the PVA polymer electrolyte These compositePVAacid salt polymer electrolytes show a highly potentialfor applications on fuel cell systems
Acknowledgment The financial supported for thisstudy from the University of Tabuk Saudi Arabia underthe project No 21211432H are gratefully acknowledged
References and Notes1 J Lee Y Lee W Chae and Y Sung Enhanced ionic conductiv-
ity in PEO-LiClO4 hybrid electrolytes by structural modificationJ Electroceram 17 941 (2006)
2 M Sundar and S Selladurai Effect of fillers on Magnesium-poly(ethylene oxide) solid polymer electrolyte Ionics 12 281 (2006)
3 V Subba Reddy Ch A P Jin Q Y Zhu L Q Mai and W ChenPreparation and characterization of (PVP+NaClO4 electrolytes forbattery applications Eur Phys J E Soft Matter 19 471 (2006)
4 M B Armand Polymer electrolytes Ann Rev Mater Sci 16 245(1986)
5 J R MacCullum and C A Vincent Polymer Electrolytes ReviewsElsevier Applied Science Publisher London (1987) and (1989)Vols 1ndash2
6 D E Fenton J M Parker and P V Wright Complexes of alkalimetal ions with poly(ethylene oxide) Polymer 14 589 (1973)
7 C W Walker Jr and M Salomon Improvement of ionic conductivityin plasticized PEO-based solid polymer electrolytes J ElectrochemSoc 140 3409 (1993)
8 C A Finch Polyvinylalcohol Wiley Interscience Pub New York(1973)
9 F Ahmad and E Sheha Preparation and physical properties of(PVA)07 (NaBr)03(H3PO4xM solid acid membrane for phosphoricacidmdashFuel cells J Advanced Research 4 155 (2013)
10 T Dippel K D Kreuer J C Lassegravegues and D Rodriguez Protonconductivity in fused phosphoric acid A 1H31P PFG-NMR and QNSstudy Solid State Ionics 61 41 (1993)
11 S Uuml Ccedilelik A Aslan and A Bozkurt Phosphoric acid-dopedpoly(1-vinyl-124-triazole) as water-free proton conducting polymerelectrolytes Solid State Ionics 179 683 (2008)
12 P Donoso W Gorecki C Berthier F Defendini C Poinsignon andM B Armand NMR conductivity and neutron scattering investiga-tion of ionic dynamics in the anhydrous polymer protonic conductorPEO(H3PO4x Solid State Ionics 28ndash30 969 (1988)
13 E Sheha Preparation and physical properties of(PVA)075(NH4Br)025(H2SO4xM solid acid membrane Journal ofNon-Crystalline Solids 356 2282 (2010)
14 A Aslan S Uuml Ccedilelik and A Bozkurt Proton-conducting proper-ties of the membranes based on poly(vinyl phosphonic acid) graftedpoly(glycidyl methacrylate) Solid State Ionics 180 1240 (2009)
15 M F Daniel B Desbat F Cruege O Trinquet and J C LasseguesSolid state protonic conductors Poly(ethyleneimine) sulfates andphosphates Solid State Ionics 28ndash30 637 (1988)
16 R Tanaka H Yamamoto A Shono K Kubo and M SakuraiProton conducting behavior in non-crosslinked and crosslinkedpolyethylenimine with excess phosphoric acid Electrochim Acta45 1385 (2000)
17 S R Samms S Wasmus and R F Savinell Thermal stability ofproton conducting acid doped Polybenzimidazole in simulated fuelcell Environments J Electrochem Soc 143 1225 (1996)
18 Q Li R He J-A Gao J O Jensen and N J Bjerrum The CO poi-soning effect in PEMFCs operational at temperatures up to 200 CJ Electrochem Soc 150 A1599 (2003)
19 H Pu W H Meyer and G Wegner Proton transport in polybenz-imidazole blended with H3PO4 or H2SO4 J Polymer Sci B PolymerPhys 40 663 (2002)
20 Y Zhai H Zhang Y Zhang and D Xing A novel H3PO4NafionndashPBI composite membrane for enhanced durability of high tempera-ture PEM fuel cells J Power Source 169 259 (2007)
21 B Samy and E Sheha Impact of hydroquinone on thermal andelectrical properties of plasticized [poly(vinylalcohol)]07 (LiBr)03-(H2SO4
minus125 molL solid acid membrane Polymer Int 60 1142 (2011)
22 A Hassen T Hanafy S El Sayed and A Himanshu Dielectricrelaxation and alternating current conductivity of polyvinylidene flu-oride doped with lanthanum chloride J Appl Physics 110 114(2011)
23 S Mahrous and T Hanafy Dielectric analysis of chlorinatedpolyvinyl chloride stabilized with di-n-octyltin maleate J AppliedPolymer Science 113 316 (2009)
24 B Wagner and C Wagner Electrical conductivity measurements oncuprous halides J Chem Phys 26 1597 (1957)
25 M Hema S Selvasekerapandian A Sakunthala D Arunkumarand H Nithy Structural vibrational and electrical characterizationof PVAndashNH4Br polymer electrolyte system Physica B 403 2740(2008)
26 E Barsoukov and J Ross Macdonald Impedance SpectroscopyTheory Experiment and Applications-Wiley-Interscience (2005)
27 K P Singh and P N Gupta Study of dielectric relaxation in polymerelectrolytes Eur Polym J 34 1023 (1998)
28 R Baskaran S Selvasekharapandian H Kumar andG Bhuvaneswari Dielectric and conductivity relaxations in PVAcbased Ionics 10 129 (2004)
29 J R Chetia M Maullick A Dutta and N N Dass Role of poly(2-dimethylaminoethylmethacerylate) salt as solid state ionics MaterSci Eng B 107 134 (2004)
30 P K C Pillai P Khurana and A Trilateral Dielectric studies ofpoly(methyl methacrylate)polystyrene double layer system J MatSci Lett 5 629 (1986)
31 M S Michael M E Jacob S Prabaharan and S RadhakrishnaEnhanced lithium ion transport in PEO-based solid polymer elec-trolytes employing a novel class of plasticizers Solid State Ionics98 167 (1997)
32 A K Jonscher The lsquouniversalrsquo dielectric response Nature 267 673(1977)
33 M Ahmad S H Sabeeh and S A Hussen Electrical and opticalproperties of PVALiI polymer electrolyte films Asian Transactionson Science amp Technology 1 16 (2012)
Mater Express Vol 4 2014 489
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Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
34 E Sheha and M K El-Mansy A high voltage magnesium batterybased on H2SO4-doped (PVA)07(NaBr)03 solid polymer electrolyteJ Power Sources 185 1509 (2008)
35 S R Majid and A K Arof Electrical behavior of proton-conductingchitosan-phosphoric acid-based electrolytes Physica B 390 209(2007)
36 A Kyritsis P Pissis and J Grammatikakis Dielectric relax-ation spectroscopy in poly(hydroxyethyl acrylates)water hydrogelsJ Polymer Sci Part B Polymer Phys 33 1737 (1995)
37 E Nora Dielectric Properties and Molecular Behavior Series inPhysical Chemistry Publishers Van Nostrand (1969)
38 G K Prajapati R Roshan and P N Gupta Effect of plasticizeron ionic transport and dielectric properties of PVAndashH3PO4 protonconducting polymeric electrolytes J Phys Chem Solids 71 1717(2010)
39 E Sheha Ionic conductivity and dielectric properties of plasticizedPVA07(LiBr)03(H2SO427 M solid acid membrane and its perfor-mance in a magnesium battery Solid State Ionics 180 1575 (2009)
Received 1 July 2014 RevisedAccepted 24 August 2014
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Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
addition of acid salt into PVA polymer matrix greatly aug-mented the domain of amorphous region (ie XRD crystalpeak reduces) This indicates that the PVAacid salt poly-mer electrolyte film becomes much amorphous Notice thatthe degree of amorphous increases with increasing the con-tents of acid salt There is a significant motion of polymerchain in the amorphous phase or some defects while non-conducting in the crystalline phase The characteristic ofthe PVAacid salt polymer electrolyte film shows excellentionic conductivity property This is due to the more free-volume and flexible of local PVA chain segmental motionin the PVAacid salt polymer electrolyte22ndash24
The morphology of the free acid salt polymer electrolyte(x = 0) and composite PVAacid salt polymer electrolytefilm (with 0 ge x gt 04) has been examined by SEM andthe images are shown in Figure 2 The free acid salt poly-mer electrolyte film is observed to have uniform a homo-geneous and dense material Figure 2(a) The small amountof acid salt (x= 01) composite polymer electrolyte film isobserved to have uniform small pores at microscopic levelFigure 2(b) In the composite acid salt polymer electrolyte(x = 02) slightly larger in size and uniformly distributedpores are observed Figure 2(c) The uniformly dispersedpores in the polymer microstructure lead to the retentionof liquid electrolyte and formation of their better connec-tivity through the polymer giving rise to have possibilityof high ionic conductivity
32 Transference Number MeasurementThe transference numbers corresponding to ionic (tionand electronic (tele transport have been calculated for
Fig 2 The SEM micrograph for the surface ofPVA1minusx(MgBr2x2(H3PO4x2 solid acid salt polymer electrolyte with(a) x = 00 (b) x = 01 (c) x = 02 and (d) x = 03
all compositions of PVAacid salt polymer electrolytesystems using dc polarization method In this methodthe dc current is monitored as a function of time onthe application of fixed dc voltage (15 V) across thesample with copper blocking electrodes When acid saltincreases the pores size increases (Fig 2(d)) Figure 3shows the result of dc polarization measurements at 30 Cfor (PVA)06(MgBr202(H3PO402 membrane The transfer-ence numbers have been calculated from the polarizationcurrent versus time plot using the standard equation25
tion =Iiminus If
Ii(1)
where Ii is the initial current and If is the final resid-ual current The ionic transference number (tion) for thecomposition of the (x = 40 wt) electrolyte systems liesbetween 093 and 096 This suggests that the charge trans-port in these electrolyte films is predominantly ions
33 Temperature Dependence of Ionic ConductivityImpedance spectroscopy Figures 4(a) (b) shows the ColendashCole plots of Zprime versus Zprimeprime (where Zprime and Zprimeprime are the realand imaginary parts of the complex impedance respec-tively) of pure PVA and various compositions of com-plexed films with acid salt at different temperatures anddifferent frequencies These plots are single semicirculararcs with their centrersquos laying below the real axis at anangle The finite value of distribution parameter anda depressed arc are typical for a material with multirelax-ation processes26 Also the arcs have a non-zero inter-section with the real axis in the high frequency regionFurther there occurs a reduction in the size of these plotswith rise in temperature and acid salt contents The semi-circle represents the bulk conductivity which is due to the
Fig 3 Polarization current as a function of time for x= 04 PVAacidsalt polymer electrolyte
Mater Express Vol 4 2014 485
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Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
(a)
(b)
Fig 4 Complex impedance plots of PVA1minusx(MgBr2x2(PWA)x2acid salt polymer electrolyte (a) different acid salt concentration at303 K and (b) different temperatures (x = 01)
parallel combination of bulk resistance and bulk capaci-tance of the polymer electrolytes Considering the equiva-lent circuit model the values of Zprime and Zprimeprime are given by
Zprime = Rs +Rp
1+2C2pR
2p
and Zprimeprime = minusCpR2p
1+2C2pR
2p
(2)
where Rs Rp and Cp are the series resistor parallel resis-tor and parallel capacitor respectively Where = 2f isthe angular frequencyThese equations predict that the values of Zprime and Zprimeprime
should decrease with increasing temperature as the valuesof Rp and Rs go on decreasing with rise in temperature inaccordance with equation C = Cp+12R2
pC2p
This causes shrinking of the ColendashCole plots withincrease in temperature and acid salt contentsSingh et al27 have studied the relaxation characteristics
of PVA-H3PO4 and PVA-H2SO4 complex electrolytes inthe form of thin films samples and observed the impedancespectra as depressed single semicircular arcs for differentsamples corresponding to their two types of relaxation pro-cesses which are interpreted in terms of dipole-segmental
motion (-relaxation) and side chain dipole group motion(-relaxation) These results suggest that the migrationof charges (ions) may occur through the free volume ofmatrix polymer which can be represented by a resis-tor On the other hand non-migration charges (chains ofpolymer) polarized and can be therefore represented by acapacitor The decrease in resistance of the polymer elec-trolyte is due to the enhancement of the ionic mobility andthe number of carrier ions with acid salt concentration andtemperature28
The bulk electrical resistance (Rb of the material isobtained from the ColendashCole plots with the intercept of thehigh frequency side on the X-axis Analysis of the spec-tra yields information about the properties of the PVAacidsalt polymer electrolyte such as bulk resistance Rb Tak-ing into account the thickness of the PVAacid salt elec-trolyte films the Rb value was converted into the ionicconductivity value according to the formula
= L
RbA(3)
where L is the thickness (cm) of the PVAacid salt polymerelectrolyte A the area of the blocking electrode (cm2) andRb is the bulk resistance ( of PVAacid salt polymerelectrolyteFigure 5 shows the ionic conductivity values for the
PVAacid salt polymer electrolytes with different contentsof acid salt It can be seen clearly that the ionic conductiv-ity of the PVAacid salt SPE can be significantly enhancedwhen the content of acid salt increasesFigure 6 represents the temperature dependence of ionic
conductivity for all compositions of PVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytes It has been found that theionic conductivity of the PVAacid salt SPE increases withincreasing temperature for all compositions indicating
Fig 5 The Influence of acid salt content on ionic conductivity ofPVA1minusx(MgBr2x2(H3PO4x2 solid acid salt polymer electrolyte
486 Mater Express Vol 4 2014
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Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
Fig 6 Arrhenius plot for PVA1minusx(MgBr2x2(H3PO4x2 solid acidsalt polymer electrolyte
Arrhenius type thermally activated process given by therelation
= o exp(minus Ea
RT
)(4)
where o is a pre-exponential factor Ea the activationenergy and T is the temperature in Kelvin This can beexplained on the basis of the free volume model29 andhopping of charge carriers between the localized states30
Since poly(vinyl alcohol) is a linear polymer with carbonchain as the back bone the polymer chains which are lessentangled are capable of causing electrical conductivityFurther PVA being a polar polymer ionizes the MgBr2
salt into anions and cations under the influence of theapplied electric field and temperature These ions hopbetween the localized states and cause enhanced con-ductivity Further when the temperature is increased thevibration energy of a segmental is sufficient to push againstthe hydrostatic pressure imposed by its neighboring atomsand create a small amount of space surrounding its ownvolume in which vibration motion can occur31 There-fore the free volume around the polymer chain causes themobility of ions and polymer segments and hence the con-ductivity The increment of temperature causes the increasein conductivity due to the increased free volume and theirrespective ionic and segmental mobility The amorphous
Table I Effect of the acid salt concentration on the activation energies(Ea and conduction index (n) values
nature also provides a bigger free volume in the poly-mer electrolytes system upon increasing temperature32
The ln versus 103T plots obtains the activation energy(Ea of the PVAacid salt SPE which is dependent on thecontents of acid salt in the polymer matrixIt has been found that the highest conductivity poly-
mer electrolyte (x = 04) has the lowest activation energy(038 eV) see Table I It is noteworthy that the poly-mer electrolytes with low values of activation energies aredesirable for practical applicationsFigure 7 shows the frequency-dependent conductiv-
ity of PVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytesThe plot shows two regions The first region observedat low frequency plateau region corresponds to the fre-quency independent conductivity (dc The second regionobserved at the high frequency dispersion region whichcorresponds to the conductivity increases with increasingfrequency This behavior obeys the universal power law13
tot= dc+An (5)
where dc is the dc conductivity (the extrapolation of theplateau region to zero frequency) A is the pre-exponentialfactor is the angular frequency and n the fractionalexponent which lies between 0 and 1 According to thejump relaxation model at low frequencies ions can jumpfrom one site to its neighboring site While at higher fre-quencies due to the short time periods the probability forions to go back to their initial sites increases which causesincrease in the conductivity3334 The values of the expo-nent n have been obtained using the least square fitting ofEq (5) it can be observed that the exponent n decreaseswith increasing concentration of the acid salt see Table IThis behavior can be interpreted in light of the fact thatdoping of acid salt increases the number of chain segmentsthat are responsive to the external electric field frequencyThe study of dielectric relaxation in solid polymer elec-
trolytes is a powerful approach for obtaining information
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
about the characteristics of ionic and molecular interac-tions The dielectric parameters associated with relaxationprocesses are of particular significance in ion conductingpolymers where the dielectric constant plays a fundamen-tal role which shows the ability of a polymer material todissolve saltsThe dielectric constant was used as an indicator to
show that the increase in conductivity is mainly due to anincrease in the number density of mobile ions35 The rela-tionship between complex impedance dielectric permit-tivity and dielectric loss can be shown in the followingformulae prime = CpLoA primeprime = o where prime
denotes the real part of dielectric function primeprime as theimaginary part of dielectric function or dielectric loss ando as the permittivity of the free space Figures 8(a)(b) shows the variation of the dielectric permittivity prime
and dielectric loss primeprime for PVA1minusx(MgBr2x2 (H3PO4x2polymer electrolytes versus frequency at room tempera-ture 30 C The figure show that prime and primeprime a graduallydecrease with increasing frequency for all prepared sam-ples The decrease of prime and primeprime with frequency can beassociated to the inability of dipoles to rotate rapidly lead-ing to a lag between frequency of oscillating dipole and
Fig 8 Frequency dependence of (a) Dielectric constant prime and(b) dielectric loss primeprime for PVA1minusx(MgBr2x2(H3PO4x2 solid acid saltpolymer electrolyte
that of applied field The variation indicates that at low fre-quencies the dielectric constant is high due to the interfa-cial polarization and the dielectric loss (primeprime) becomes verylarge at lower frequencies due to free charge motion withinthe material36
This behavior can be described by the Debye dispersionrelation37
prime + s minus1+2132
primeprime s minus131+2132
(6)
where and s are the static and infinite dielectric per-mittivity 13 is the relaxation time and is the angularfrequencyFigures 9(a)ndash(b) show the variation of dielec-
tric permittivity prime and dielectric loss primeprime forPVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytes withtemperature at 1 kHz The value of prime and primeprime increaseswith temperature The observed increase in of prime anddielectric loss primeprime with temperature could be attributed todecrease in the viscosity of the polymeric material Thisleads to an increment in the degree of dipole orientationof polar dielectric material and hence dielectric constant
Fig 9 Temperature dependence of (a) Dielectric constant prime and(b) dielectric loss primeprime for PVA1minusx(MgBr2x2(H3PO4x2 solid acid saltpolymer electrolyte
488 Mater Express Vol 4 2014
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
increases38 Dipolar molecules should be able to orientfrom one equilibrium position to another relatively easilyand contribute to absorption39
4 CONCLUSIONPVAacid salt polymer electrolytes with a different com-position were obtained by a solution casting method Thephyso-chemiacal characteristic properties of the compositeare systematically studied by using a XRD SEM and ACimpedance method The XRD study reveals the amorphousnature of the polymer-acid salt complexes that produceshigh ionic diffusivity The introduction of acid salt to thePVA polymer electrolytes has proved to be a convenientmethod to increase the ionic conductivity at ambient tem-perature Addition of acid salt causes an enhancement inits mobility and charge carrier concentration The ionictransference number of mobile ions has been estimated tobe in the range 093 and 096 revealing that the conductingspecies are predominantly due to ions The temperaturedependence of conductivity of PVAacid salt obeys Arrhe-nius relation in the temperature range studied In fact theionic conductivity value greatly depends on the acid saltcontents in the PVA polymer electrolyte These compositePVAacid salt polymer electrolytes show a highly potentialfor applications on fuel cell systems
Acknowledgment The financial supported for thisstudy from the University of Tabuk Saudi Arabia underthe project No 21211432H are gratefully acknowledged
References and Notes1 J Lee Y Lee W Chae and Y Sung Enhanced ionic conductiv-
ity in PEO-LiClO4 hybrid electrolytes by structural modificationJ Electroceram 17 941 (2006)
2 M Sundar and S Selladurai Effect of fillers on Magnesium-poly(ethylene oxide) solid polymer electrolyte Ionics 12 281 (2006)
3 V Subba Reddy Ch A P Jin Q Y Zhu L Q Mai and W ChenPreparation and characterization of (PVP+NaClO4 electrolytes forbattery applications Eur Phys J E Soft Matter 19 471 (2006)
4 M B Armand Polymer electrolytes Ann Rev Mater Sci 16 245(1986)
5 J R MacCullum and C A Vincent Polymer Electrolytes ReviewsElsevier Applied Science Publisher London (1987) and (1989)Vols 1ndash2
6 D E Fenton J M Parker and P V Wright Complexes of alkalimetal ions with poly(ethylene oxide) Polymer 14 589 (1973)
7 C W Walker Jr and M Salomon Improvement of ionic conductivityin plasticized PEO-based solid polymer electrolytes J ElectrochemSoc 140 3409 (1993)
8 C A Finch Polyvinylalcohol Wiley Interscience Pub New York(1973)
9 F Ahmad and E Sheha Preparation and physical properties of(PVA)07 (NaBr)03(H3PO4xM solid acid membrane for phosphoricacidmdashFuel cells J Advanced Research 4 155 (2013)
10 T Dippel K D Kreuer J C Lassegravegues and D Rodriguez Protonconductivity in fused phosphoric acid A 1H31P PFG-NMR and QNSstudy Solid State Ionics 61 41 (1993)
11 S Uuml Ccedilelik A Aslan and A Bozkurt Phosphoric acid-dopedpoly(1-vinyl-124-triazole) as water-free proton conducting polymerelectrolytes Solid State Ionics 179 683 (2008)
12 P Donoso W Gorecki C Berthier F Defendini C Poinsignon andM B Armand NMR conductivity and neutron scattering investiga-tion of ionic dynamics in the anhydrous polymer protonic conductorPEO(H3PO4x Solid State Ionics 28ndash30 969 (1988)
13 E Sheha Preparation and physical properties of(PVA)075(NH4Br)025(H2SO4xM solid acid membrane Journal ofNon-Crystalline Solids 356 2282 (2010)
14 A Aslan S Uuml Ccedilelik and A Bozkurt Proton-conducting proper-ties of the membranes based on poly(vinyl phosphonic acid) graftedpoly(glycidyl methacrylate) Solid State Ionics 180 1240 (2009)
15 M F Daniel B Desbat F Cruege O Trinquet and J C LasseguesSolid state protonic conductors Poly(ethyleneimine) sulfates andphosphates Solid State Ionics 28ndash30 637 (1988)
16 R Tanaka H Yamamoto A Shono K Kubo and M SakuraiProton conducting behavior in non-crosslinked and crosslinkedpolyethylenimine with excess phosphoric acid Electrochim Acta45 1385 (2000)
17 S R Samms S Wasmus and R F Savinell Thermal stability ofproton conducting acid doped Polybenzimidazole in simulated fuelcell Environments J Electrochem Soc 143 1225 (1996)
18 Q Li R He J-A Gao J O Jensen and N J Bjerrum The CO poi-soning effect in PEMFCs operational at temperatures up to 200 CJ Electrochem Soc 150 A1599 (2003)
19 H Pu W H Meyer and G Wegner Proton transport in polybenz-imidazole blended with H3PO4 or H2SO4 J Polymer Sci B PolymerPhys 40 663 (2002)
20 Y Zhai H Zhang Y Zhang and D Xing A novel H3PO4NafionndashPBI composite membrane for enhanced durability of high tempera-ture PEM fuel cells J Power Source 169 259 (2007)
21 B Samy and E Sheha Impact of hydroquinone on thermal andelectrical properties of plasticized [poly(vinylalcohol)]07 (LiBr)03-(H2SO4
minus125 molL solid acid membrane Polymer Int 60 1142 (2011)
22 A Hassen T Hanafy S El Sayed and A Himanshu Dielectricrelaxation and alternating current conductivity of polyvinylidene flu-oride doped with lanthanum chloride J Appl Physics 110 114(2011)
23 S Mahrous and T Hanafy Dielectric analysis of chlorinatedpolyvinyl chloride stabilized with di-n-octyltin maleate J AppliedPolymer Science 113 316 (2009)
24 B Wagner and C Wagner Electrical conductivity measurements oncuprous halides J Chem Phys 26 1597 (1957)
25 M Hema S Selvasekerapandian A Sakunthala D Arunkumarand H Nithy Structural vibrational and electrical characterizationof PVAndashNH4Br polymer electrolyte system Physica B 403 2740(2008)
26 E Barsoukov and J Ross Macdonald Impedance SpectroscopyTheory Experiment and Applications-Wiley-Interscience (2005)
27 K P Singh and P N Gupta Study of dielectric relaxation in polymerelectrolytes Eur Polym J 34 1023 (1998)
28 R Baskaran S Selvasekharapandian H Kumar andG Bhuvaneswari Dielectric and conductivity relaxations in PVAcbased Ionics 10 129 (2004)
29 J R Chetia M Maullick A Dutta and N N Dass Role of poly(2-dimethylaminoethylmethacerylate) salt as solid state ionics MaterSci Eng B 107 134 (2004)
30 P K C Pillai P Khurana and A Trilateral Dielectric studies ofpoly(methyl methacrylate)polystyrene double layer system J MatSci Lett 5 629 (1986)
31 M S Michael M E Jacob S Prabaharan and S RadhakrishnaEnhanced lithium ion transport in PEO-based solid polymer elec-trolytes employing a novel class of plasticizers Solid State Ionics98 167 (1997)
32 A K Jonscher The lsquouniversalrsquo dielectric response Nature 267 673(1977)
33 M Ahmad S H Sabeeh and S A Hussen Electrical and opticalproperties of PVALiI polymer electrolyte films Asian Transactionson Science amp Technology 1 16 (2012)
Mater Express Vol 4 2014 489
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Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
34 E Sheha and M K El-Mansy A high voltage magnesium batterybased on H2SO4-doped (PVA)07(NaBr)03 solid polymer electrolyteJ Power Sources 185 1509 (2008)
35 S R Majid and A K Arof Electrical behavior of proton-conductingchitosan-phosphoric acid-based electrolytes Physica B 390 209(2007)
36 A Kyritsis P Pissis and J Grammatikakis Dielectric relax-ation spectroscopy in poly(hydroxyethyl acrylates)water hydrogelsJ Polymer Sci Part B Polymer Phys 33 1737 (1995)
37 E Nora Dielectric Properties and Molecular Behavior Series inPhysical Chemistry Publishers Van Nostrand (1969)
38 G K Prajapati R Roshan and P N Gupta Effect of plasticizeron ionic transport and dielectric properties of PVAndashH3PO4 protonconducting polymeric electrolytes J Phys Chem Solids 71 1717(2010)
39 E Sheha Ionic conductivity and dielectric properties of plasticizedPVA07(LiBr)03(H2SO427 M solid acid membrane and its perfor-mance in a magnesium battery Solid State Ionics 180 1575 (2009)
Received 1 July 2014 RevisedAccepted 24 August 2014
490 Mater Express Vol 4 2014
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
(a)
(b)
Fig 4 Complex impedance plots of PVA1minusx(MgBr2x2(PWA)x2acid salt polymer electrolyte (a) different acid salt concentration at303 K and (b) different temperatures (x = 01)
parallel combination of bulk resistance and bulk capaci-tance of the polymer electrolytes Considering the equiva-lent circuit model the values of Zprime and Zprimeprime are given by
Zprime = Rs +Rp
1+2C2pR
2p
and Zprimeprime = minusCpR2p
1+2C2pR
2p
(2)
where Rs Rp and Cp are the series resistor parallel resis-tor and parallel capacitor respectively Where = 2f isthe angular frequencyThese equations predict that the values of Zprime and Zprimeprime
should decrease with increasing temperature as the valuesof Rp and Rs go on decreasing with rise in temperature inaccordance with equation C = Cp+12R2
pC2p
This causes shrinking of the ColendashCole plots withincrease in temperature and acid salt contentsSingh et al27 have studied the relaxation characteristics
of PVA-H3PO4 and PVA-H2SO4 complex electrolytes inthe form of thin films samples and observed the impedancespectra as depressed single semicircular arcs for differentsamples corresponding to their two types of relaxation pro-cesses which are interpreted in terms of dipole-segmental
motion (-relaxation) and side chain dipole group motion(-relaxation) These results suggest that the migrationof charges (ions) may occur through the free volume ofmatrix polymer which can be represented by a resis-tor On the other hand non-migration charges (chains ofpolymer) polarized and can be therefore represented by acapacitor The decrease in resistance of the polymer elec-trolyte is due to the enhancement of the ionic mobility andthe number of carrier ions with acid salt concentration andtemperature28
The bulk electrical resistance (Rb of the material isobtained from the ColendashCole plots with the intercept of thehigh frequency side on the X-axis Analysis of the spec-tra yields information about the properties of the PVAacidsalt polymer electrolyte such as bulk resistance Rb Tak-ing into account the thickness of the PVAacid salt elec-trolyte films the Rb value was converted into the ionicconductivity value according to the formula
= L
RbA(3)
where L is the thickness (cm) of the PVAacid salt polymerelectrolyte A the area of the blocking electrode (cm2) andRb is the bulk resistance ( of PVAacid salt polymerelectrolyteFigure 5 shows the ionic conductivity values for the
PVAacid salt polymer electrolytes with different contentsof acid salt It can be seen clearly that the ionic conductiv-ity of the PVAacid salt SPE can be significantly enhancedwhen the content of acid salt increasesFigure 6 represents the temperature dependence of ionic
conductivity for all compositions of PVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytes It has been found that theionic conductivity of the PVAacid salt SPE increases withincreasing temperature for all compositions indicating
Fig 5 The Influence of acid salt content on ionic conductivity ofPVA1minusx(MgBr2x2(H3PO4x2 solid acid salt polymer electrolyte
486 Mater Express Vol 4 2014
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
Fig 6 Arrhenius plot for PVA1minusx(MgBr2x2(H3PO4x2 solid acidsalt polymer electrolyte
Arrhenius type thermally activated process given by therelation
= o exp(minus Ea
RT
)(4)
where o is a pre-exponential factor Ea the activationenergy and T is the temperature in Kelvin This can beexplained on the basis of the free volume model29 andhopping of charge carriers between the localized states30
Since poly(vinyl alcohol) is a linear polymer with carbonchain as the back bone the polymer chains which are lessentangled are capable of causing electrical conductivityFurther PVA being a polar polymer ionizes the MgBr2
salt into anions and cations under the influence of theapplied electric field and temperature These ions hopbetween the localized states and cause enhanced con-ductivity Further when the temperature is increased thevibration energy of a segmental is sufficient to push againstthe hydrostatic pressure imposed by its neighboring atomsand create a small amount of space surrounding its ownvolume in which vibration motion can occur31 There-fore the free volume around the polymer chain causes themobility of ions and polymer segments and hence the con-ductivity The increment of temperature causes the increasein conductivity due to the increased free volume and theirrespective ionic and segmental mobility The amorphous
Table I Effect of the acid salt concentration on the activation energies(Ea and conduction index (n) values
nature also provides a bigger free volume in the poly-mer electrolytes system upon increasing temperature32
The ln versus 103T plots obtains the activation energy(Ea of the PVAacid salt SPE which is dependent on thecontents of acid salt in the polymer matrixIt has been found that the highest conductivity poly-
mer electrolyte (x = 04) has the lowest activation energy(038 eV) see Table I It is noteworthy that the poly-mer electrolytes with low values of activation energies aredesirable for practical applicationsFigure 7 shows the frequency-dependent conductiv-
ity of PVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytesThe plot shows two regions The first region observedat low frequency plateau region corresponds to the fre-quency independent conductivity (dc The second regionobserved at the high frequency dispersion region whichcorresponds to the conductivity increases with increasingfrequency This behavior obeys the universal power law13
tot= dc+An (5)
where dc is the dc conductivity (the extrapolation of theplateau region to zero frequency) A is the pre-exponentialfactor is the angular frequency and n the fractionalexponent which lies between 0 and 1 According to thejump relaxation model at low frequencies ions can jumpfrom one site to its neighboring site While at higher fre-quencies due to the short time periods the probability forions to go back to their initial sites increases which causesincrease in the conductivity3334 The values of the expo-nent n have been obtained using the least square fitting ofEq (5) it can be observed that the exponent n decreaseswith increasing concentration of the acid salt see Table IThis behavior can be interpreted in light of the fact thatdoping of acid salt increases the number of chain segmentsthat are responsive to the external electric field frequencyThe study of dielectric relaxation in solid polymer elec-
trolytes is a powerful approach for obtaining information
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
about the characteristics of ionic and molecular interac-tions The dielectric parameters associated with relaxationprocesses are of particular significance in ion conductingpolymers where the dielectric constant plays a fundamen-tal role which shows the ability of a polymer material todissolve saltsThe dielectric constant was used as an indicator to
show that the increase in conductivity is mainly due to anincrease in the number density of mobile ions35 The rela-tionship between complex impedance dielectric permit-tivity and dielectric loss can be shown in the followingformulae prime = CpLoA primeprime = o where prime
denotes the real part of dielectric function primeprime as theimaginary part of dielectric function or dielectric loss ando as the permittivity of the free space Figures 8(a)(b) shows the variation of the dielectric permittivity prime
and dielectric loss primeprime for PVA1minusx(MgBr2x2 (H3PO4x2polymer electrolytes versus frequency at room tempera-ture 30 C The figure show that prime and primeprime a graduallydecrease with increasing frequency for all prepared sam-ples The decrease of prime and primeprime with frequency can beassociated to the inability of dipoles to rotate rapidly lead-ing to a lag between frequency of oscillating dipole and
Fig 8 Frequency dependence of (a) Dielectric constant prime and(b) dielectric loss primeprime for PVA1minusx(MgBr2x2(H3PO4x2 solid acid saltpolymer electrolyte
that of applied field The variation indicates that at low fre-quencies the dielectric constant is high due to the interfa-cial polarization and the dielectric loss (primeprime) becomes verylarge at lower frequencies due to free charge motion withinthe material36
This behavior can be described by the Debye dispersionrelation37
prime + s minus1+2132
primeprime s minus131+2132
(6)
where and s are the static and infinite dielectric per-mittivity 13 is the relaxation time and is the angularfrequencyFigures 9(a)ndash(b) show the variation of dielec-
tric permittivity prime and dielectric loss primeprime forPVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytes withtemperature at 1 kHz The value of prime and primeprime increaseswith temperature The observed increase in of prime anddielectric loss primeprime with temperature could be attributed todecrease in the viscosity of the polymeric material Thisleads to an increment in the degree of dipole orientationof polar dielectric material and hence dielectric constant
Fig 9 Temperature dependence of (a) Dielectric constant prime and(b) dielectric loss primeprime for PVA1minusx(MgBr2x2(H3PO4x2 solid acid saltpolymer electrolyte
488 Mater Express Vol 4 2014
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
increases38 Dipolar molecules should be able to orientfrom one equilibrium position to another relatively easilyand contribute to absorption39
4 CONCLUSIONPVAacid salt polymer electrolytes with a different com-position were obtained by a solution casting method Thephyso-chemiacal characteristic properties of the compositeare systematically studied by using a XRD SEM and ACimpedance method The XRD study reveals the amorphousnature of the polymer-acid salt complexes that produceshigh ionic diffusivity The introduction of acid salt to thePVA polymer electrolytes has proved to be a convenientmethod to increase the ionic conductivity at ambient tem-perature Addition of acid salt causes an enhancement inits mobility and charge carrier concentration The ionictransference number of mobile ions has been estimated tobe in the range 093 and 096 revealing that the conductingspecies are predominantly due to ions The temperaturedependence of conductivity of PVAacid salt obeys Arrhe-nius relation in the temperature range studied In fact theionic conductivity value greatly depends on the acid saltcontents in the PVA polymer electrolyte These compositePVAacid salt polymer electrolytes show a highly potentialfor applications on fuel cell systems
Acknowledgment The financial supported for thisstudy from the University of Tabuk Saudi Arabia underthe project No 21211432H are gratefully acknowledged
References and Notes1 J Lee Y Lee W Chae and Y Sung Enhanced ionic conductiv-
ity in PEO-LiClO4 hybrid electrolytes by structural modificationJ Electroceram 17 941 (2006)
2 M Sundar and S Selladurai Effect of fillers on Magnesium-poly(ethylene oxide) solid polymer electrolyte Ionics 12 281 (2006)
3 V Subba Reddy Ch A P Jin Q Y Zhu L Q Mai and W ChenPreparation and characterization of (PVP+NaClO4 electrolytes forbattery applications Eur Phys J E Soft Matter 19 471 (2006)
4 M B Armand Polymer electrolytes Ann Rev Mater Sci 16 245(1986)
5 J R MacCullum and C A Vincent Polymer Electrolytes ReviewsElsevier Applied Science Publisher London (1987) and (1989)Vols 1ndash2
6 D E Fenton J M Parker and P V Wright Complexes of alkalimetal ions with poly(ethylene oxide) Polymer 14 589 (1973)
7 C W Walker Jr and M Salomon Improvement of ionic conductivityin plasticized PEO-based solid polymer electrolytes J ElectrochemSoc 140 3409 (1993)
8 C A Finch Polyvinylalcohol Wiley Interscience Pub New York(1973)
9 F Ahmad and E Sheha Preparation and physical properties of(PVA)07 (NaBr)03(H3PO4xM solid acid membrane for phosphoricacidmdashFuel cells J Advanced Research 4 155 (2013)
10 T Dippel K D Kreuer J C Lassegravegues and D Rodriguez Protonconductivity in fused phosphoric acid A 1H31P PFG-NMR and QNSstudy Solid State Ionics 61 41 (1993)
11 S Uuml Ccedilelik A Aslan and A Bozkurt Phosphoric acid-dopedpoly(1-vinyl-124-triazole) as water-free proton conducting polymerelectrolytes Solid State Ionics 179 683 (2008)
12 P Donoso W Gorecki C Berthier F Defendini C Poinsignon andM B Armand NMR conductivity and neutron scattering investiga-tion of ionic dynamics in the anhydrous polymer protonic conductorPEO(H3PO4x Solid State Ionics 28ndash30 969 (1988)
13 E Sheha Preparation and physical properties of(PVA)075(NH4Br)025(H2SO4xM solid acid membrane Journal ofNon-Crystalline Solids 356 2282 (2010)
14 A Aslan S Uuml Ccedilelik and A Bozkurt Proton-conducting proper-ties of the membranes based on poly(vinyl phosphonic acid) graftedpoly(glycidyl methacrylate) Solid State Ionics 180 1240 (2009)
15 M F Daniel B Desbat F Cruege O Trinquet and J C LasseguesSolid state protonic conductors Poly(ethyleneimine) sulfates andphosphates Solid State Ionics 28ndash30 637 (1988)
16 R Tanaka H Yamamoto A Shono K Kubo and M SakuraiProton conducting behavior in non-crosslinked and crosslinkedpolyethylenimine with excess phosphoric acid Electrochim Acta45 1385 (2000)
17 S R Samms S Wasmus and R F Savinell Thermal stability ofproton conducting acid doped Polybenzimidazole in simulated fuelcell Environments J Electrochem Soc 143 1225 (1996)
18 Q Li R He J-A Gao J O Jensen and N J Bjerrum The CO poi-soning effect in PEMFCs operational at temperatures up to 200 CJ Electrochem Soc 150 A1599 (2003)
19 H Pu W H Meyer and G Wegner Proton transport in polybenz-imidazole blended with H3PO4 or H2SO4 J Polymer Sci B PolymerPhys 40 663 (2002)
20 Y Zhai H Zhang Y Zhang and D Xing A novel H3PO4NafionndashPBI composite membrane for enhanced durability of high tempera-ture PEM fuel cells J Power Source 169 259 (2007)
21 B Samy and E Sheha Impact of hydroquinone on thermal andelectrical properties of plasticized [poly(vinylalcohol)]07 (LiBr)03-(H2SO4
minus125 molL solid acid membrane Polymer Int 60 1142 (2011)
22 A Hassen T Hanafy S El Sayed and A Himanshu Dielectricrelaxation and alternating current conductivity of polyvinylidene flu-oride doped with lanthanum chloride J Appl Physics 110 114(2011)
23 S Mahrous and T Hanafy Dielectric analysis of chlorinatedpolyvinyl chloride stabilized with di-n-octyltin maleate J AppliedPolymer Science 113 316 (2009)
24 B Wagner and C Wagner Electrical conductivity measurements oncuprous halides J Chem Phys 26 1597 (1957)
25 M Hema S Selvasekerapandian A Sakunthala D Arunkumarand H Nithy Structural vibrational and electrical characterizationof PVAndashNH4Br polymer electrolyte system Physica B 403 2740(2008)
26 E Barsoukov and J Ross Macdonald Impedance SpectroscopyTheory Experiment and Applications-Wiley-Interscience (2005)
27 K P Singh and P N Gupta Study of dielectric relaxation in polymerelectrolytes Eur Polym J 34 1023 (1998)
28 R Baskaran S Selvasekharapandian H Kumar andG Bhuvaneswari Dielectric and conductivity relaxations in PVAcbased Ionics 10 129 (2004)
29 J R Chetia M Maullick A Dutta and N N Dass Role of poly(2-dimethylaminoethylmethacerylate) salt as solid state ionics MaterSci Eng B 107 134 (2004)
30 P K C Pillai P Khurana and A Trilateral Dielectric studies ofpoly(methyl methacrylate)polystyrene double layer system J MatSci Lett 5 629 (1986)
31 M S Michael M E Jacob S Prabaharan and S RadhakrishnaEnhanced lithium ion transport in PEO-based solid polymer elec-trolytes employing a novel class of plasticizers Solid State Ionics98 167 (1997)
32 A K Jonscher The lsquouniversalrsquo dielectric response Nature 267 673(1977)
33 M Ahmad S H Sabeeh and S A Hussen Electrical and opticalproperties of PVALiI polymer electrolyte films Asian Transactionson Science amp Technology 1 16 (2012)
Mater Express Vol 4 2014 489
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
34 E Sheha and M K El-Mansy A high voltage magnesium batterybased on H2SO4-doped (PVA)07(NaBr)03 solid polymer electrolyteJ Power Sources 185 1509 (2008)
35 S R Majid and A K Arof Electrical behavior of proton-conductingchitosan-phosphoric acid-based electrolytes Physica B 390 209(2007)
36 A Kyritsis P Pissis and J Grammatikakis Dielectric relax-ation spectroscopy in poly(hydroxyethyl acrylates)water hydrogelsJ Polymer Sci Part B Polymer Phys 33 1737 (1995)
37 E Nora Dielectric Properties and Molecular Behavior Series inPhysical Chemistry Publishers Van Nostrand (1969)
38 G K Prajapati R Roshan and P N Gupta Effect of plasticizeron ionic transport and dielectric properties of PVAndashH3PO4 protonconducting polymeric electrolytes J Phys Chem Solids 71 1717(2010)
39 E Sheha Ionic conductivity and dielectric properties of plasticizedPVA07(LiBr)03(H2SO427 M solid acid membrane and its perfor-mance in a magnesium battery Solid State Ionics 180 1575 (2009)
Received 1 July 2014 RevisedAccepted 24 August 2014
490 Mater Express Vol 4 2014
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
Fig 6 Arrhenius plot for PVA1minusx(MgBr2x2(H3PO4x2 solid acidsalt polymer electrolyte
Arrhenius type thermally activated process given by therelation
= o exp(minus Ea
RT
)(4)
where o is a pre-exponential factor Ea the activationenergy and T is the temperature in Kelvin This can beexplained on the basis of the free volume model29 andhopping of charge carriers between the localized states30
Since poly(vinyl alcohol) is a linear polymer with carbonchain as the back bone the polymer chains which are lessentangled are capable of causing electrical conductivityFurther PVA being a polar polymer ionizes the MgBr2
salt into anions and cations under the influence of theapplied electric field and temperature These ions hopbetween the localized states and cause enhanced con-ductivity Further when the temperature is increased thevibration energy of a segmental is sufficient to push againstthe hydrostatic pressure imposed by its neighboring atomsand create a small amount of space surrounding its ownvolume in which vibration motion can occur31 There-fore the free volume around the polymer chain causes themobility of ions and polymer segments and hence the con-ductivity The increment of temperature causes the increasein conductivity due to the increased free volume and theirrespective ionic and segmental mobility The amorphous
Table I Effect of the acid salt concentration on the activation energies(Ea and conduction index (n) values
nature also provides a bigger free volume in the poly-mer electrolytes system upon increasing temperature32
The ln versus 103T plots obtains the activation energy(Ea of the PVAacid salt SPE which is dependent on thecontents of acid salt in the polymer matrixIt has been found that the highest conductivity poly-
mer electrolyte (x = 04) has the lowest activation energy(038 eV) see Table I It is noteworthy that the poly-mer electrolytes with low values of activation energies aredesirable for practical applicationsFigure 7 shows the frequency-dependent conductiv-
ity of PVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytesThe plot shows two regions The first region observedat low frequency plateau region corresponds to the fre-quency independent conductivity (dc The second regionobserved at the high frequency dispersion region whichcorresponds to the conductivity increases with increasingfrequency This behavior obeys the universal power law13
tot= dc+An (5)
where dc is the dc conductivity (the extrapolation of theplateau region to zero frequency) A is the pre-exponentialfactor is the angular frequency and n the fractionalexponent which lies between 0 and 1 According to thejump relaxation model at low frequencies ions can jumpfrom one site to its neighboring site While at higher fre-quencies due to the short time periods the probability forions to go back to their initial sites increases which causesincrease in the conductivity3334 The values of the expo-nent n have been obtained using the least square fitting ofEq (5) it can be observed that the exponent n decreaseswith increasing concentration of the acid salt see Table IThis behavior can be interpreted in light of the fact thatdoping of acid salt increases the number of chain segmentsthat are responsive to the external electric field frequencyThe study of dielectric relaxation in solid polymer elec-
trolytes is a powerful approach for obtaining information
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
about the characteristics of ionic and molecular interac-tions The dielectric parameters associated with relaxationprocesses are of particular significance in ion conductingpolymers where the dielectric constant plays a fundamen-tal role which shows the ability of a polymer material todissolve saltsThe dielectric constant was used as an indicator to
show that the increase in conductivity is mainly due to anincrease in the number density of mobile ions35 The rela-tionship between complex impedance dielectric permit-tivity and dielectric loss can be shown in the followingformulae prime = CpLoA primeprime = o where prime
denotes the real part of dielectric function primeprime as theimaginary part of dielectric function or dielectric loss ando as the permittivity of the free space Figures 8(a)(b) shows the variation of the dielectric permittivity prime
and dielectric loss primeprime for PVA1minusx(MgBr2x2 (H3PO4x2polymer electrolytes versus frequency at room tempera-ture 30 C The figure show that prime and primeprime a graduallydecrease with increasing frequency for all prepared sam-ples The decrease of prime and primeprime with frequency can beassociated to the inability of dipoles to rotate rapidly lead-ing to a lag between frequency of oscillating dipole and
Fig 8 Frequency dependence of (a) Dielectric constant prime and(b) dielectric loss primeprime for PVA1minusx(MgBr2x2(H3PO4x2 solid acid saltpolymer electrolyte
that of applied field The variation indicates that at low fre-quencies the dielectric constant is high due to the interfa-cial polarization and the dielectric loss (primeprime) becomes verylarge at lower frequencies due to free charge motion withinthe material36
This behavior can be described by the Debye dispersionrelation37
prime + s minus1+2132
primeprime s minus131+2132
(6)
where and s are the static and infinite dielectric per-mittivity 13 is the relaxation time and is the angularfrequencyFigures 9(a)ndash(b) show the variation of dielec-
tric permittivity prime and dielectric loss primeprime forPVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytes withtemperature at 1 kHz The value of prime and primeprime increaseswith temperature The observed increase in of prime anddielectric loss primeprime with temperature could be attributed todecrease in the viscosity of the polymeric material Thisleads to an increment in the degree of dipole orientationof polar dielectric material and hence dielectric constant
Fig 9 Temperature dependence of (a) Dielectric constant prime and(b) dielectric loss primeprime for PVA1minusx(MgBr2x2(H3PO4x2 solid acid saltpolymer electrolyte
488 Mater Express Vol 4 2014
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
increases38 Dipolar molecules should be able to orientfrom one equilibrium position to another relatively easilyand contribute to absorption39
4 CONCLUSIONPVAacid salt polymer electrolytes with a different com-position were obtained by a solution casting method Thephyso-chemiacal characteristic properties of the compositeare systematically studied by using a XRD SEM and ACimpedance method The XRD study reveals the amorphousnature of the polymer-acid salt complexes that produceshigh ionic diffusivity The introduction of acid salt to thePVA polymer electrolytes has proved to be a convenientmethod to increase the ionic conductivity at ambient tem-perature Addition of acid salt causes an enhancement inits mobility and charge carrier concentration The ionictransference number of mobile ions has been estimated tobe in the range 093 and 096 revealing that the conductingspecies are predominantly due to ions The temperaturedependence of conductivity of PVAacid salt obeys Arrhe-nius relation in the temperature range studied In fact theionic conductivity value greatly depends on the acid saltcontents in the PVA polymer electrolyte These compositePVAacid salt polymer electrolytes show a highly potentialfor applications on fuel cell systems
Acknowledgment The financial supported for thisstudy from the University of Tabuk Saudi Arabia underthe project No 21211432H are gratefully acknowledged
References and Notes1 J Lee Y Lee W Chae and Y Sung Enhanced ionic conductiv-
ity in PEO-LiClO4 hybrid electrolytes by structural modificationJ Electroceram 17 941 (2006)
2 M Sundar and S Selladurai Effect of fillers on Magnesium-poly(ethylene oxide) solid polymer electrolyte Ionics 12 281 (2006)
3 V Subba Reddy Ch A P Jin Q Y Zhu L Q Mai and W ChenPreparation and characterization of (PVP+NaClO4 electrolytes forbattery applications Eur Phys J E Soft Matter 19 471 (2006)
4 M B Armand Polymer electrolytes Ann Rev Mater Sci 16 245(1986)
5 J R MacCullum and C A Vincent Polymer Electrolytes ReviewsElsevier Applied Science Publisher London (1987) and (1989)Vols 1ndash2
6 D E Fenton J M Parker and P V Wright Complexes of alkalimetal ions with poly(ethylene oxide) Polymer 14 589 (1973)
7 C W Walker Jr and M Salomon Improvement of ionic conductivityin plasticized PEO-based solid polymer electrolytes J ElectrochemSoc 140 3409 (1993)
8 C A Finch Polyvinylalcohol Wiley Interscience Pub New York(1973)
9 F Ahmad and E Sheha Preparation and physical properties of(PVA)07 (NaBr)03(H3PO4xM solid acid membrane for phosphoricacidmdashFuel cells J Advanced Research 4 155 (2013)
10 T Dippel K D Kreuer J C Lassegravegues and D Rodriguez Protonconductivity in fused phosphoric acid A 1H31P PFG-NMR and QNSstudy Solid State Ionics 61 41 (1993)
11 S Uuml Ccedilelik A Aslan and A Bozkurt Phosphoric acid-dopedpoly(1-vinyl-124-triazole) as water-free proton conducting polymerelectrolytes Solid State Ionics 179 683 (2008)
12 P Donoso W Gorecki C Berthier F Defendini C Poinsignon andM B Armand NMR conductivity and neutron scattering investiga-tion of ionic dynamics in the anhydrous polymer protonic conductorPEO(H3PO4x Solid State Ionics 28ndash30 969 (1988)
13 E Sheha Preparation and physical properties of(PVA)075(NH4Br)025(H2SO4xM solid acid membrane Journal ofNon-Crystalline Solids 356 2282 (2010)
14 A Aslan S Uuml Ccedilelik and A Bozkurt Proton-conducting proper-ties of the membranes based on poly(vinyl phosphonic acid) graftedpoly(glycidyl methacrylate) Solid State Ionics 180 1240 (2009)
15 M F Daniel B Desbat F Cruege O Trinquet and J C LasseguesSolid state protonic conductors Poly(ethyleneimine) sulfates andphosphates Solid State Ionics 28ndash30 637 (1988)
16 R Tanaka H Yamamoto A Shono K Kubo and M SakuraiProton conducting behavior in non-crosslinked and crosslinkedpolyethylenimine with excess phosphoric acid Electrochim Acta45 1385 (2000)
17 S R Samms S Wasmus and R F Savinell Thermal stability ofproton conducting acid doped Polybenzimidazole in simulated fuelcell Environments J Electrochem Soc 143 1225 (1996)
18 Q Li R He J-A Gao J O Jensen and N J Bjerrum The CO poi-soning effect in PEMFCs operational at temperatures up to 200 CJ Electrochem Soc 150 A1599 (2003)
19 H Pu W H Meyer and G Wegner Proton transport in polybenz-imidazole blended with H3PO4 or H2SO4 J Polymer Sci B PolymerPhys 40 663 (2002)
20 Y Zhai H Zhang Y Zhang and D Xing A novel H3PO4NafionndashPBI composite membrane for enhanced durability of high tempera-ture PEM fuel cells J Power Source 169 259 (2007)
21 B Samy and E Sheha Impact of hydroquinone on thermal andelectrical properties of plasticized [poly(vinylalcohol)]07 (LiBr)03-(H2SO4
minus125 molL solid acid membrane Polymer Int 60 1142 (2011)
22 A Hassen T Hanafy S El Sayed and A Himanshu Dielectricrelaxation and alternating current conductivity of polyvinylidene flu-oride doped with lanthanum chloride J Appl Physics 110 114(2011)
23 S Mahrous and T Hanafy Dielectric analysis of chlorinatedpolyvinyl chloride stabilized with di-n-octyltin maleate J AppliedPolymer Science 113 316 (2009)
24 B Wagner and C Wagner Electrical conductivity measurements oncuprous halides J Chem Phys 26 1597 (1957)
25 M Hema S Selvasekerapandian A Sakunthala D Arunkumarand H Nithy Structural vibrational and electrical characterizationof PVAndashNH4Br polymer electrolyte system Physica B 403 2740(2008)
26 E Barsoukov and J Ross Macdonald Impedance SpectroscopyTheory Experiment and Applications-Wiley-Interscience (2005)
27 K P Singh and P N Gupta Study of dielectric relaxation in polymerelectrolytes Eur Polym J 34 1023 (1998)
28 R Baskaran S Selvasekharapandian H Kumar andG Bhuvaneswari Dielectric and conductivity relaxations in PVAcbased Ionics 10 129 (2004)
29 J R Chetia M Maullick A Dutta and N N Dass Role of poly(2-dimethylaminoethylmethacerylate) salt as solid state ionics MaterSci Eng B 107 134 (2004)
30 P K C Pillai P Khurana and A Trilateral Dielectric studies ofpoly(methyl methacrylate)polystyrene double layer system J MatSci Lett 5 629 (1986)
31 M S Michael M E Jacob S Prabaharan and S RadhakrishnaEnhanced lithium ion transport in PEO-based solid polymer elec-trolytes employing a novel class of plasticizers Solid State Ionics98 167 (1997)
32 A K Jonscher The lsquouniversalrsquo dielectric response Nature 267 673(1977)
33 M Ahmad S H Sabeeh and S A Hussen Electrical and opticalproperties of PVALiI polymer electrolyte films Asian Transactionson Science amp Technology 1 16 (2012)
Mater Express Vol 4 2014 489
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
34 E Sheha and M K El-Mansy A high voltage magnesium batterybased on H2SO4-doped (PVA)07(NaBr)03 solid polymer electrolyteJ Power Sources 185 1509 (2008)
35 S R Majid and A K Arof Electrical behavior of proton-conductingchitosan-phosphoric acid-based electrolytes Physica B 390 209(2007)
36 A Kyritsis P Pissis and J Grammatikakis Dielectric relax-ation spectroscopy in poly(hydroxyethyl acrylates)water hydrogelsJ Polymer Sci Part B Polymer Phys 33 1737 (1995)
37 E Nora Dielectric Properties and Molecular Behavior Series inPhysical Chemistry Publishers Van Nostrand (1969)
38 G K Prajapati R Roshan and P N Gupta Effect of plasticizeron ionic transport and dielectric properties of PVAndashH3PO4 protonconducting polymeric electrolytes J Phys Chem Solids 71 1717(2010)
39 E Sheha Ionic conductivity and dielectric properties of plasticizedPVA07(LiBr)03(H2SO427 M solid acid membrane and its perfor-mance in a magnesium battery Solid State Ionics 180 1575 (2009)
Received 1 July 2014 RevisedAccepted 24 August 2014
490 Mater Express Vol 4 2014
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
about the characteristics of ionic and molecular interac-tions The dielectric parameters associated with relaxationprocesses are of particular significance in ion conductingpolymers where the dielectric constant plays a fundamen-tal role which shows the ability of a polymer material todissolve saltsThe dielectric constant was used as an indicator to
show that the increase in conductivity is mainly due to anincrease in the number density of mobile ions35 The rela-tionship between complex impedance dielectric permit-tivity and dielectric loss can be shown in the followingformulae prime = CpLoA primeprime = o where prime
denotes the real part of dielectric function primeprime as theimaginary part of dielectric function or dielectric loss ando as the permittivity of the free space Figures 8(a)(b) shows the variation of the dielectric permittivity prime
and dielectric loss primeprime for PVA1minusx(MgBr2x2 (H3PO4x2polymer electrolytes versus frequency at room tempera-ture 30 C The figure show that prime and primeprime a graduallydecrease with increasing frequency for all prepared sam-ples The decrease of prime and primeprime with frequency can beassociated to the inability of dipoles to rotate rapidly lead-ing to a lag between frequency of oscillating dipole and
Fig 8 Frequency dependence of (a) Dielectric constant prime and(b) dielectric loss primeprime for PVA1minusx(MgBr2x2(H3PO4x2 solid acid saltpolymer electrolyte
that of applied field The variation indicates that at low fre-quencies the dielectric constant is high due to the interfa-cial polarization and the dielectric loss (primeprime) becomes verylarge at lower frequencies due to free charge motion withinthe material36
This behavior can be described by the Debye dispersionrelation37
prime + s minus1+2132
primeprime s minus131+2132
(6)
where and s are the static and infinite dielectric per-mittivity 13 is the relaxation time and is the angularfrequencyFigures 9(a)ndash(b) show the variation of dielec-
tric permittivity prime and dielectric loss primeprime forPVA1minusx(MgBr2x2(H3PO4x2 polymer electrolytes withtemperature at 1 kHz The value of prime and primeprime increaseswith temperature The observed increase in of prime anddielectric loss primeprime with temperature could be attributed todecrease in the viscosity of the polymeric material Thisleads to an increment in the degree of dipole orientationof polar dielectric material and hence dielectric constant
Fig 9 Temperature dependence of (a) Dielectric constant prime and(b) dielectric loss primeprime for PVA1minusx(MgBr2x2(H3PO4x2 solid acid saltpolymer electrolyte
488 Mater Express Vol 4 2014
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
increases38 Dipolar molecules should be able to orientfrom one equilibrium position to another relatively easilyand contribute to absorption39
4 CONCLUSIONPVAacid salt polymer electrolytes with a different com-position were obtained by a solution casting method Thephyso-chemiacal characteristic properties of the compositeare systematically studied by using a XRD SEM and ACimpedance method The XRD study reveals the amorphousnature of the polymer-acid salt complexes that produceshigh ionic diffusivity The introduction of acid salt to thePVA polymer electrolytes has proved to be a convenientmethod to increase the ionic conductivity at ambient tem-perature Addition of acid salt causes an enhancement inits mobility and charge carrier concentration The ionictransference number of mobile ions has been estimated tobe in the range 093 and 096 revealing that the conductingspecies are predominantly due to ions The temperaturedependence of conductivity of PVAacid salt obeys Arrhe-nius relation in the temperature range studied In fact theionic conductivity value greatly depends on the acid saltcontents in the PVA polymer electrolyte These compositePVAacid salt polymer electrolytes show a highly potentialfor applications on fuel cell systems
Acknowledgment The financial supported for thisstudy from the University of Tabuk Saudi Arabia underthe project No 21211432H are gratefully acknowledged
References and Notes1 J Lee Y Lee W Chae and Y Sung Enhanced ionic conductiv-
ity in PEO-LiClO4 hybrid electrolytes by structural modificationJ Electroceram 17 941 (2006)
2 M Sundar and S Selladurai Effect of fillers on Magnesium-poly(ethylene oxide) solid polymer electrolyte Ionics 12 281 (2006)
3 V Subba Reddy Ch A P Jin Q Y Zhu L Q Mai and W ChenPreparation and characterization of (PVP+NaClO4 electrolytes forbattery applications Eur Phys J E Soft Matter 19 471 (2006)
4 M B Armand Polymer electrolytes Ann Rev Mater Sci 16 245(1986)
5 J R MacCullum and C A Vincent Polymer Electrolytes ReviewsElsevier Applied Science Publisher London (1987) and (1989)Vols 1ndash2
6 D E Fenton J M Parker and P V Wright Complexes of alkalimetal ions with poly(ethylene oxide) Polymer 14 589 (1973)
7 C W Walker Jr and M Salomon Improvement of ionic conductivityin plasticized PEO-based solid polymer electrolytes J ElectrochemSoc 140 3409 (1993)
8 C A Finch Polyvinylalcohol Wiley Interscience Pub New York(1973)
9 F Ahmad and E Sheha Preparation and physical properties of(PVA)07 (NaBr)03(H3PO4xM solid acid membrane for phosphoricacidmdashFuel cells J Advanced Research 4 155 (2013)
10 T Dippel K D Kreuer J C Lassegravegues and D Rodriguez Protonconductivity in fused phosphoric acid A 1H31P PFG-NMR and QNSstudy Solid State Ionics 61 41 (1993)
11 S Uuml Ccedilelik A Aslan and A Bozkurt Phosphoric acid-dopedpoly(1-vinyl-124-triazole) as water-free proton conducting polymerelectrolytes Solid State Ionics 179 683 (2008)
12 P Donoso W Gorecki C Berthier F Defendini C Poinsignon andM B Armand NMR conductivity and neutron scattering investiga-tion of ionic dynamics in the anhydrous polymer protonic conductorPEO(H3PO4x Solid State Ionics 28ndash30 969 (1988)
13 E Sheha Preparation and physical properties of(PVA)075(NH4Br)025(H2SO4xM solid acid membrane Journal ofNon-Crystalline Solids 356 2282 (2010)
14 A Aslan S Uuml Ccedilelik and A Bozkurt Proton-conducting proper-ties of the membranes based on poly(vinyl phosphonic acid) graftedpoly(glycidyl methacrylate) Solid State Ionics 180 1240 (2009)
15 M F Daniel B Desbat F Cruege O Trinquet and J C LasseguesSolid state protonic conductors Poly(ethyleneimine) sulfates andphosphates Solid State Ionics 28ndash30 637 (1988)
16 R Tanaka H Yamamoto A Shono K Kubo and M SakuraiProton conducting behavior in non-crosslinked and crosslinkedpolyethylenimine with excess phosphoric acid Electrochim Acta45 1385 (2000)
17 S R Samms S Wasmus and R F Savinell Thermal stability ofproton conducting acid doped Polybenzimidazole in simulated fuelcell Environments J Electrochem Soc 143 1225 (1996)
18 Q Li R He J-A Gao J O Jensen and N J Bjerrum The CO poi-soning effect in PEMFCs operational at temperatures up to 200 CJ Electrochem Soc 150 A1599 (2003)
19 H Pu W H Meyer and G Wegner Proton transport in polybenz-imidazole blended with H3PO4 or H2SO4 J Polymer Sci B PolymerPhys 40 663 (2002)
20 Y Zhai H Zhang Y Zhang and D Xing A novel H3PO4NafionndashPBI composite membrane for enhanced durability of high tempera-ture PEM fuel cells J Power Source 169 259 (2007)
21 B Samy and E Sheha Impact of hydroquinone on thermal andelectrical properties of plasticized [poly(vinylalcohol)]07 (LiBr)03-(H2SO4
minus125 molL solid acid membrane Polymer Int 60 1142 (2011)
22 A Hassen T Hanafy S El Sayed and A Himanshu Dielectricrelaxation and alternating current conductivity of polyvinylidene flu-oride doped with lanthanum chloride J Appl Physics 110 114(2011)
23 S Mahrous and T Hanafy Dielectric analysis of chlorinatedpolyvinyl chloride stabilized with di-n-octyltin maleate J AppliedPolymer Science 113 316 (2009)
24 B Wagner and C Wagner Electrical conductivity measurements oncuprous halides J Chem Phys 26 1597 (1957)
25 M Hema S Selvasekerapandian A Sakunthala D Arunkumarand H Nithy Structural vibrational and electrical characterizationof PVAndashNH4Br polymer electrolyte system Physica B 403 2740(2008)
26 E Barsoukov and J Ross Macdonald Impedance SpectroscopyTheory Experiment and Applications-Wiley-Interscience (2005)
27 K P Singh and P N Gupta Study of dielectric relaxation in polymerelectrolytes Eur Polym J 34 1023 (1998)
28 R Baskaran S Selvasekharapandian H Kumar andG Bhuvaneswari Dielectric and conductivity relaxations in PVAcbased Ionics 10 129 (2004)
29 J R Chetia M Maullick A Dutta and N N Dass Role of poly(2-dimethylaminoethylmethacerylate) salt as solid state ionics MaterSci Eng B 107 134 (2004)
30 P K C Pillai P Khurana and A Trilateral Dielectric studies ofpoly(methyl methacrylate)polystyrene double layer system J MatSci Lett 5 629 (1986)
31 M S Michael M E Jacob S Prabaharan and S RadhakrishnaEnhanced lithium ion transport in PEO-based solid polymer elec-trolytes employing a novel class of plasticizers Solid State Ionics98 167 (1997)
32 A K Jonscher The lsquouniversalrsquo dielectric response Nature 267 673(1977)
33 M Ahmad S H Sabeeh and S A Hussen Electrical and opticalproperties of PVALiI polymer electrolyte films Asian Transactionson Science amp Technology 1 16 (2012)
Mater Express Vol 4 2014 489
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
34 E Sheha and M K El-Mansy A high voltage magnesium batterybased on H2SO4-doped (PVA)07(NaBr)03 solid polymer electrolyteJ Power Sources 185 1509 (2008)
35 S R Majid and A K Arof Electrical behavior of proton-conductingchitosan-phosphoric acid-based electrolytes Physica B 390 209(2007)
36 A Kyritsis P Pissis and J Grammatikakis Dielectric relax-ation spectroscopy in poly(hydroxyethyl acrylates)water hydrogelsJ Polymer Sci Part B Polymer Phys 33 1737 (1995)
37 E Nora Dielectric Properties and Molecular Behavior Series inPhysical Chemistry Publishers Van Nostrand (1969)
38 G K Prajapati R Roshan and P N Gupta Effect of plasticizeron ionic transport and dielectric properties of PVAndashH3PO4 protonconducting polymeric electrolytes J Phys Chem Solids 71 1717(2010)
39 E Sheha Ionic conductivity and dielectric properties of plasticizedPVA07(LiBr)03(H2SO427 M solid acid membrane and its perfor-mance in a magnesium battery Solid State Ionics 180 1575 (2009)
Received 1 July 2014 RevisedAccepted 24 August 2014
490 Mater Express Vol 4 2014
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytesKhalil et al
Article
increases38 Dipolar molecules should be able to orientfrom one equilibrium position to another relatively easilyand contribute to absorption39
4 CONCLUSIONPVAacid salt polymer electrolytes with a different com-position were obtained by a solution casting method Thephyso-chemiacal characteristic properties of the compositeare systematically studied by using a XRD SEM and ACimpedance method The XRD study reveals the amorphousnature of the polymer-acid salt complexes that produceshigh ionic diffusivity The introduction of acid salt to thePVA polymer electrolytes has proved to be a convenientmethod to increase the ionic conductivity at ambient tem-perature Addition of acid salt causes an enhancement inits mobility and charge carrier concentration The ionictransference number of mobile ions has been estimated tobe in the range 093 and 096 revealing that the conductingspecies are predominantly due to ions The temperaturedependence of conductivity of PVAacid salt obeys Arrhe-nius relation in the temperature range studied In fact theionic conductivity value greatly depends on the acid saltcontents in the PVA polymer electrolyte These compositePVAacid salt polymer electrolytes show a highly potentialfor applications on fuel cell systems
Acknowledgment The financial supported for thisstudy from the University of Tabuk Saudi Arabia underthe project No 21211432H are gratefully acknowledged
References and Notes1 J Lee Y Lee W Chae and Y Sung Enhanced ionic conductiv-
ity in PEO-LiClO4 hybrid electrolytes by structural modificationJ Electroceram 17 941 (2006)
2 M Sundar and S Selladurai Effect of fillers on Magnesium-poly(ethylene oxide) solid polymer electrolyte Ionics 12 281 (2006)
3 V Subba Reddy Ch A P Jin Q Y Zhu L Q Mai and W ChenPreparation and characterization of (PVP+NaClO4 electrolytes forbattery applications Eur Phys J E Soft Matter 19 471 (2006)
4 M B Armand Polymer electrolytes Ann Rev Mater Sci 16 245(1986)
5 J R MacCullum and C A Vincent Polymer Electrolytes ReviewsElsevier Applied Science Publisher London (1987) and (1989)Vols 1ndash2
6 D E Fenton J M Parker and P V Wright Complexes of alkalimetal ions with poly(ethylene oxide) Polymer 14 589 (1973)
7 C W Walker Jr and M Salomon Improvement of ionic conductivityin plasticized PEO-based solid polymer electrolytes J ElectrochemSoc 140 3409 (1993)
8 C A Finch Polyvinylalcohol Wiley Interscience Pub New York(1973)
9 F Ahmad and E Sheha Preparation and physical properties of(PVA)07 (NaBr)03(H3PO4xM solid acid membrane for phosphoricacidmdashFuel cells J Advanced Research 4 155 (2013)
10 T Dippel K D Kreuer J C Lassegravegues and D Rodriguez Protonconductivity in fused phosphoric acid A 1H31P PFG-NMR and QNSstudy Solid State Ionics 61 41 (1993)
11 S Uuml Ccedilelik A Aslan and A Bozkurt Phosphoric acid-dopedpoly(1-vinyl-124-triazole) as water-free proton conducting polymerelectrolytes Solid State Ionics 179 683 (2008)
12 P Donoso W Gorecki C Berthier F Defendini C Poinsignon andM B Armand NMR conductivity and neutron scattering investiga-tion of ionic dynamics in the anhydrous polymer protonic conductorPEO(H3PO4x Solid State Ionics 28ndash30 969 (1988)
13 E Sheha Preparation and physical properties of(PVA)075(NH4Br)025(H2SO4xM solid acid membrane Journal ofNon-Crystalline Solids 356 2282 (2010)
14 A Aslan S Uuml Ccedilelik and A Bozkurt Proton-conducting proper-ties of the membranes based on poly(vinyl phosphonic acid) graftedpoly(glycidyl methacrylate) Solid State Ionics 180 1240 (2009)
15 M F Daniel B Desbat F Cruege O Trinquet and J C LasseguesSolid state protonic conductors Poly(ethyleneimine) sulfates andphosphates Solid State Ionics 28ndash30 637 (1988)
16 R Tanaka H Yamamoto A Shono K Kubo and M SakuraiProton conducting behavior in non-crosslinked and crosslinkedpolyethylenimine with excess phosphoric acid Electrochim Acta45 1385 (2000)
17 S R Samms S Wasmus and R F Savinell Thermal stability ofproton conducting acid doped Polybenzimidazole in simulated fuelcell Environments J Electrochem Soc 143 1225 (1996)
18 Q Li R He J-A Gao J O Jensen and N J Bjerrum The CO poi-soning effect in PEMFCs operational at temperatures up to 200 CJ Electrochem Soc 150 A1599 (2003)
19 H Pu W H Meyer and G Wegner Proton transport in polybenz-imidazole blended with H3PO4 or H2SO4 J Polymer Sci B PolymerPhys 40 663 (2002)
20 Y Zhai H Zhang Y Zhang and D Xing A novel H3PO4NafionndashPBI composite membrane for enhanced durability of high tempera-ture PEM fuel cells J Power Source 169 259 (2007)
21 B Samy and E Sheha Impact of hydroquinone on thermal andelectrical properties of plasticized [poly(vinylalcohol)]07 (LiBr)03-(H2SO4
minus125 molL solid acid membrane Polymer Int 60 1142 (2011)
22 A Hassen T Hanafy S El Sayed and A Himanshu Dielectricrelaxation and alternating current conductivity of polyvinylidene flu-oride doped with lanthanum chloride J Appl Physics 110 114(2011)
23 S Mahrous and T Hanafy Dielectric analysis of chlorinatedpolyvinyl chloride stabilized with di-n-octyltin maleate J AppliedPolymer Science 113 316 (2009)
24 B Wagner and C Wagner Electrical conductivity measurements oncuprous halides J Chem Phys 26 1597 (1957)
25 M Hema S Selvasekerapandian A Sakunthala D Arunkumarand H Nithy Structural vibrational and electrical characterizationof PVAndashNH4Br polymer electrolyte system Physica B 403 2740(2008)
26 E Barsoukov and J Ross Macdonald Impedance SpectroscopyTheory Experiment and Applications-Wiley-Interscience (2005)
27 K P Singh and P N Gupta Study of dielectric relaxation in polymerelectrolytes Eur Polym J 34 1023 (1998)
28 R Baskaran S Selvasekharapandian H Kumar andG Bhuvaneswari Dielectric and conductivity relaxations in PVAcbased Ionics 10 129 (2004)
29 J R Chetia M Maullick A Dutta and N N Dass Role of poly(2-dimethylaminoethylmethacerylate) salt as solid state ionics MaterSci Eng B 107 134 (2004)
30 P K C Pillai P Khurana and A Trilateral Dielectric studies ofpoly(methyl methacrylate)polystyrene double layer system J MatSci Lett 5 629 (1986)
31 M S Michael M E Jacob S Prabaharan and S RadhakrishnaEnhanced lithium ion transport in PEO-based solid polymer elec-trolytes employing a novel class of plasticizers Solid State Ionics98 167 (1997)
32 A K Jonscher The lsquouniversalrsquo dielectric response Nature 267 673(1977)
33 M Ahmad S H Sabeeh and S A Hussen Electrical and opticalproperties of PVALiI polymer electrolyte films Asian Transactionson Science amp Technology 1 16 (2012)
Mater Express Vol 4 2014 489
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
34 E Sheha and M K El-Mansy A high voltage magnesium batterybased on H2SO4-doped (PVA)07(NaBr)03 solid polymer electrolyteJ Power Sources 185 1509 (2008)
35 S R Majid and A K Arof Electrical behavior of proton-conductingchitosan-phosphoric acid-based electrolytes Physica B 390 209(2007)
36 A Kyritsis P Pissis and J Grammatikakis Dielectric relax-ation spectroscopy in poly(hydroxyethyl acrylates)water hydrogelsJ Polymer Sci Part B Polymer Phys 33 1737 (1995)
37 E Nora Dielectric Properties and Molecular Behavior Series inPhysical Chemistry Publishers Van Nostrand (1969)
38 G K Prajapati R Roshan and P N Gupta Effect of plasticizeron ionic transport and dielectric properties of PVAndashH3PO4 protonconducting polymeric electrolytes J Phys Chem Solids 71 1717(2010)
39 E Sheha Ionic conductivity and dielectric properties of plasticizedPVA07(LiBr)03(H2SO427 M solid acid membrane and its perfor-mance in a magnesium battery Solid State Ionics 180 1575 (2009)
Received 1 July 2014 RevisedAccepted 24 August 2014
490 Mater Express Vol 4 2014
Delivered by Publishing Technology to Guest UserIP 19322736253 On Sun 28 Dec 2014 131804
Copyright American Scientific Publishers
Materials ExpressSynthesis and characterization of poly(vinyl alcohol)-acid salt polymer electrolytes
Khalil et al
Article
34 E Sheha and M K El-Mansy A high voltage magnesium batterybased on H2SO4-doped (PVA)07(NaBr)03 solid polymer electrolyteJ Power Sources 185 1509 (2008)
35 S R Majid and A K Arof Electrical behavior of proton-conductingchitosan-phosphoric acid-based electrolytes Physica B 390 209(2007)
36 A Kyritsis P Pissis and J Grammatikakis Dielectric relax-ation spectroscopy in poly(hydroxyethyl acrylates)water hydrogelsJ Polymer Sci Part B Polymer Phys 33 1737 (1995)
37 E Nora Dielectric Properties and Molecular Behavior Series inPhysical Chemistry Publishers Van Nostrand (1969)
38 G K Prajapati R Roshan and P N Gupta Effect of plasticizeron ionic transport and dielectric properties of PVAndashH3PO4 protonconducting polymeric electrolytes J Phys Chem Solids 71 1717(2010)
39 E Sheha Ionic conductivity and dielectric properties of plasticizedPVA07(LiBr)03(H2SO427 M solid acid membrane and its perfor-mance in a magnesium battery Solid State Ionics 180 1575 (2009)
Received 1 July 2014 RevisedAccepted 24 August 2014
