MechanochemicalMechanochemical synthesis andsynthesis andinvestigation of investigation of nanomaterialsnanomaterials for lithiumfor lithium--ion ion
batteriesbatteries
N.V. KosovaN.V. KosovaInstitute of Solid State Chemistry and Mechanochemistry SB RAS,
Novosibirsk, Russia
MolE 2012 Dubna, August 27-30
2
OutlineOutline
• Intercalation electrode materials for lithium-ion batteries. Challenge for nanosized materials
• Mechanical activation as a promising method to prepare nanomaterials. Synthetic reactions
• Investigation of as prepared materials. Some examples
• Composite cathode materials
3
Structural types of cathode materialsStructural types of cathode materials
LiО2
LiО2
LiО2
LiО2
СоО2
CoО2
a
c
CoО2
Layered (2D)Spinel (3D) Frame-work (1D)
Fe Li P
4
Comparison of cathode materialsComparison of cathode materials
LiFePO4
LiMn2O4
LiCoO2
Complexity of synthesis
Structural, chemical and thermal stability
Electric conductivity
Compound/property
decr
ease
s
incr
ease
s
incr
ease
s
5
Materials prepared via Materials prepared via mechanochemicalmechanochemical routeroute
•• LiFePOLiFePO44
•• LiFeLiFe11--xxMnMnxxPOPO44
•• LiMnPOLiMnPO44
•• LiCoPOLiCoPO44
•• LiNiPOLiNiPO44
•• LiLi22CoPOCoPO44FF•• LiLi22NiPONiPO44FF•• LiVPOLiVPO44FF•• LiLi22FePFeP22OO77
•• LiTiLiTi22(PO(PO44))33((electrolyteelectrolyte))
•• LiMnLiMn22OO44
•• LiMnLiMn22--xxMMxxOO44
•• LiMnLiMn1.51.5NiNi0.50.5OO44(5V)(5V)
•• LiLi44TiTi55OO1212 ((anodeanode))
•• LiCoOLiCoO22
•• LiCoLiCo11--xxMMxxOO22
•• LiCoOLiCoO22--LiLi22MnOMnO33
•• LiNiOLiNiO22
•• LiNiLiNi11--xxCoCoxxOO22
•• LiNiLiNi11--xx--yyCoCoxxMnMnyyOO22
•• LiVLiV33OO88
Layered structuredLayered Layered
structuredstructuredSpinel
structuredSpinelSpinel
structuredstructuredFrame-work structured
FrameFrame--work work structuredstructured
6
Pros and cons of Pros and cons of nanosizednanosized electrode materialselectrode materials
Better utilization of nanoparticle volume
Smaller dimensional changes upon cycling; better adaptability
of nanoparticles to volumechanges under cycling
Shorter Li+ diffusion paths;increased electrode/
electrolyte surface contact;accelerated ionic transport
Increased practical Increased practical capacitycapacity
Improved structural Improved structural stabilitystability
Enhanced highEnhanced high--rate rate capabilitycapability
The particle size (and its distribution), morphology and density of the particles play a fundamental role on electrochemical performance of electrode materials
Intensification of undesirable electrode/electrolyte reactions due to
high surface area (self-discharge, poor cycling and calendar life)
Inferior packing of particles (low volumetric
energy densities)
Potentially more complex synthesis
7
Mechanical activation methodMechanical activation methodSynthetic reactionsSynthetic reactions
8
NanomaterialsNanomaterials via mechanical activationvia mechanical activation
☺ Decrease in a number of intermediate stages☺ Acceleration and simplification of the synthetic process
☺ Increase in homogeneity of the final product☺ Formation of nano-sized / nano-structured material
TwoTwo--step process:step process:1 step (MA) – grinding and plastic deformation of solids
mixing of components at molecular level (deformation mixing);2 step (T) – short-time thermal treatment formation of product
from molecular precursor supersaturated by defects
MAТ, С
Laboratory planetary mill AGO-2
Industrial activator CEM-7
9
Synthetic reactionsSynthetic reactions
• Soft mechanochemical synthesis (SMS)
• Mechanochemically assisted carbothermalreduction of d-metal compounds (CTR)
• Mechanochemically assisted interaction of covalent compounds with ionic salts
Motivation - to realize fast propagating synthesis in order to reduce contamination and energy consumption and to prepare
nanosized products.
10
1. Soft 1. Soft mechanochemicalmechanochemical synthesis (SMS)synthesis (SMS)
А(ОН)х + В(ОН)y → AB(OH)mnH2O → ABOz
MA T
1. Acceleration of initial interaction due to participation of OH groups in the processes of proton and electron transfer.
2. Formation of chemically active X-ray amorphous precursor.
3. Formation of final product by heating the precursor at moderate temperatures.
4. Significant reduction of contamination due to lower hardness of initial reagents.
5. Preparation of nanosized, pure andhomogeneous final product as a result.
SMS is generally based on the acid-base properties of the reagents.
11
SMS: LiMnSMS: LiMn22OO44LiOH + MnOx LiMn2O4
X-Ray patterns of (a) mechanically activated mixtures of LiOH with different Mn oxides and (b) the products of MA and annealing at different temperatures.
10 20 30 40 50 60 70 80
MnO
Mn2O3
MnO2
2, degree
- MnO - Mn2O3 - Li-Mn spinel
(a)
20 30 40 50 60 70
440
511
331
400
222
311
800oC
600oC
450oC
MA
2, degree
111
(b)
MnO Mn2O3 MnO2 acidity increases
SMS - fast propagating mechanochemical reaction (realized at the stage of MA)N.V. Kosova et al., Solid State Ionics 135 (2000) 107-114.
N.V. Kosova et al., J. Power Sources 97-98 (2001) 406-411.
12
5 10 15 20 25
6
5
4
3
2
1
, degree
X-ray patterns (a) and FTIR spectra (b) of the LiOH+V2O5 mixtures activated for (1) 30 sec, (2) 1 min, (3) 5 min, (4) 10 min, (5) 10 min followed by annealing at
400C, (6) 5 min followed by aging for 6 months.
● V2O5; ♦ LiV3O8; ▼ Li-V bronzes
200 400 600 800 1000
545 59
5
995
as(V-O)s(V-O)
(V=O)
6
5432
1
490
600
810
1020
545
595
745
740
920
950
995
920 95
5
Abs
orba
nce
Wavenumber, cm-1
SMS: LiVSMS: LiV33OO88
2LiOH + 3V2O5 2LiV3O8 + H2O(a) (b)
V2O5
N.V. Kosova et al., J. Solid State Chem. 160 (2001) 444-449.
13
2. 2. CarbothermalCarbothermal reductionreduction
The potential low-cost advantage of LiFePO4 is not realized if expensive Fe2+ precursors are used as reagents.
Carbothermal reduction method is relied on the use of carbon both as a selective reducing
and covering agent (J. Barker, 2003) :1) Fe3+ compounds are cheaper than Fe2+ salts;2) less hazardous gases are formed during firing;3) more easy to scale-up.
LiFePO4
Cryst. С
Amorph. C
C
LiFePO4
14
10 15 20 25 30 35 40 45 50
212321
- LiFePO4 [19-721] - Fe2O3 [33-664] - Fe3O4 [19-629] ? - (NH4 )2HPO4 [29-111] monocl. - (NH4 )2HPO4 [20-84] orhtorh. - LiFeP2O7 [80-1371] - Li3Fe2(PO4)3 [47-107] - NH4FeP2O7 {21-26] - Li3PO4 [25-1030]
700oC
550oC
450oC
300oC
MA
2, degree
112
102,
221
, 401
41012
131
1
301
211,
020
111,
201
01121
010
1
200
-10 -5 0 5 10
experiment fit Fe2O3
experiment fit Fe2+ (LiFePO
4)
experiment fit Fe2O3
Fe3+
MA mixture+ 320oC
MA mixture+ 700oC
MA mixture
Fe2O3
Velocity, mm/s
experiment fit Fe2O3
X-Ray patterns and Mössbauer spectra of the activated and annealed mixtures with Fe2O3.
MechanochemicallyMechanochemically assisted CTR of Feassisted CTR of Fe22OO33
Li2CO3 + Fe2O3 + C + 2(NH4)2HPO4 2LiFePO4 + 3H2O + 4NH3 + CO2 + CO
N.V. Kosova et al., J. Electrochem. Soc. 157 (2010) A1247-A1252.
15
CarbothermalCarbothermal reduction: LiMPOreduction: LiMPO44 (M=(M=MnMn, Fe, Co), Fe, Co)Li2CO3 + 2MnO2 + 2C + 2(NH4)2HPO4 2LiMnPO4 + 3H2O + 4NH3 + CO2 + 2CO
Li2CO3 + Fe2O3 + C + 2(NH4)2HPO4 2LiFePO4 + 3H2O + 4NH3 + CO2 + CO
3Li2CO3 + 2Co3O4 + C + 6(NH4)2HPO4 6LiCoPO4 + 12H2O + 12NH3 + 3CO2 + CO
Li2CO3 + 2NiO + 2(NH4)2HPO4 2LiNiPO4 + 3H2O + 4NH3 + CO2
20 30 40 50 60
LiNiPO4
LiCoPO4
LiFePO4
LiMnPO4
2, degree
16
3. Covalent + ionic salts3. Covalent + ionic salts
• LiCoPO4 + LiF Li2CoPO4F• LiNiPO4 + LiF Li2NiPO4F• VPO4 + LiF LiVPO4F
This approach, called “dimensional reduction”, was first outlined by Long et al. It involves a deconstruction of the bonding within a covalent metal –anion framework by reaction with an ionic reagent, to provide a less tightly connected framework that retains the metal coordination geometry and polyhedron connectivity of the parent structure (Li2CoPO4F and Li2NiPO4F). On the other hand, the formation of LiVPO4F by incorporating of LiF into the framework of VPO4 (S.g. Cmcm) represents a decrease in crystal symmetry, but here, a three-dimentional framework is maintained.
LiCoPO4
(corner-shared CO6)Li2CoPO4F
(edge-shared CoO4F2)
J.R. Long, L.S. McCarty, R.H. Holm, J. Am. Chem. Soc. 118 (1996) 4603.
17
Covalent + ionic saltsCovalent + ionic salts
15 20 25 30 35 40 45
Li2CoPO4F [Khasanova et al., 2011] LiCoPO4 Li3PO4
CoO ? Co ?
2, degree
28C_He
300C
400C
500C
600C
650C
700C
650C600C
500C
400C
300C
29C_He
LiCoPO4 + LiF Li2CoPO4F
Phase transformation under heating and cooling of the activated mixture.
D8 Advance Bruker
diffractometer, HTK 1200N temperature-controlled X-ray chamber.
Fast propagating mechanochemical reaction (realized at the stage of MA)
N.V. Kosova et al., Solid State Ionics doi:10.1016/j.ssi.2011.11.007
18
Investigation of as prepared materialsInvestigation of as prepared materials
19
Investigation methodsInvestigation methods
• X-ray powder diffraction (XRD) • Thermal analysis (DTA and TG)• Infrared spectroscopy (FTIR)• Raman spectroscopy (RS)• Mössbauer spectroscopy• Nuclear magnetic resonance spectroscopy (NMR)• Electron paramagnetic resonance spectroscopy (EPR)• X-ray photoelectron spectroscopy (XPS)• Scanning electron microscopy (SEM)• Transmission electron microscopy (TEM)• Galvanostatic cycling• Impedance spectroscopy• In situ synchrotron diffraction
Particle size and Particle size and morphologymorphology
Crystal and local Crystal and local structurestructure
Electronic Electronic structurestructure
Electrochemical Electrochemical propertiesproperties
20
Li Li -- MnMn spinelsspinels
Li4Mn5O12 – Mn3O4stoichiometric spinels
Li4Mn5O12 – -MnO2defect spinels
LiMn2O4 – Li2Mn4O9oxygen non-stoichiometric spinels
Li4Mn5O12 – Mn3O4stoichiometric spinels
Li4Mn5O12 – -MnO2defect spinels
LiMn2O4 – Li2Mn4O9oxygen non-stoichiometric spinels
C – cubicT – tetragonal
M. Thackerey et al., 1992
C
CТ
MnO
Mn3O4
-Mn2O3
Li1-Mn2O4-4/3
-MnO2
LiMn3O4
LiMn2O4LiMn2O4-
LiMnO2
Li6.5Mn5O12
Li4Mn5O12
Li1+Mn2-O4Li2MnO3
Li2Mn4O9Li1.05Mn1.95O4
4V
3V
21
V/V = 10 - 16%
Jan-Teller distortion
Mn3+ (d4)
eg
t2g
Cycling of Cycling of micronsizedmicronsized LiMnLiMn3+3+MnMn4+4+OO44
0 1 22
3
4
5
U, V
olts
x in LixMn2O4
+ e + e- e - eMn4+ [Mn4+,Mn3+] Mn3+
Fd-3m I41/amdλ-MnO2 LiMn2O4 Li2Mn2O4
Fd-3m
Two-phase reaction
Single-phase reaction
22
Charge-discharge curves of LiMn2O4-MA, annealed at different temperatures, and differential capacity plots.
0 50 100 150 200 250 3002.0
2.5
3.0
3.5
4.0
4.5 450C 600C 800C
Vol
tage
, V
Specific capacity, mAh/g
0.0 0.5 1.0 1.5 2.0 x Li
2.5 3.0 3.5 4.0-1500
-1000
-500
0
500
1000
1500 450C 600C 800C
dQ/d
E
Voltage, V
Cycling of Cycling of nanosizednanosized LiMnLiMn22OO44
Nano-spinel cannot accommodate domain boundaries between Li-rich and Li-poor phases due to interface energy, and therefore lithiation proceeds via solid solutions without domain boundaries,
enabling fast Li-ion insertion. N.V. Kosova, E.T. Devyatkina, Russ. J. of Electrochem. 48 (2012) 320-329.
23
LiNiLiNi0.50.5MnMn1.51.5OO44: structure and properties: structure and properties
0 50 100 150
3.5
4.0
4.5
5.0
700C
Vol
tage
, V
Specific capacity, mA*h*g-1
0 50 100 150
3,5
4,0
4,5
5,0800C
Vol
tage
, V
Specific capacity, mA*h*g-1Fd3m
P4332
5 V cathode material:Ni2+ two-electron reactionMn4+ electrochemically non-reactive
N.V. Kosova et al., 16 IMLB, Jeju, Korea, June 17-22, 2012.
24
Synthesis of layered LiNiSynthesis of layered LiNi0.80.8CoCo0.20.2OO22
LiOH + (Ni0.8Co0.2)(OH)2 LiOH + NiO + Co3O4
1 m 1 m
From double hydroxides From anhydrous oxides
N.V. Kosova et al., Chemistry for Sustainable Development 17 (2009) 141-149.
25
LiNiLiNi11--yyCoCoyyOO22: local structure and electrochemistry: local structure and electrochemistry
м.д.-40-30-20-10 0 102030
1
2
3
4
5
6
7Li MAS NMR spectra of LiNi1-yCoyO2:y = 1 (1); y = 0.8 (2); y = 0.6 (3); y =
0.4 (4); y = 0.2 (5); y = 0 (6). 5 10 15 20 250
50
100
150
200
250
C
C/2C/5
Spe
cific
cap
acity
, mA
hg-1
Cycle number
C/10
0 20 40 60 80 100 120 140 160 180
2,75
3,00
3,25
3,50
3,75
4,00
4,25
1 charge
1 discharge
Volta
ge, V
Specific capacity, mAh/g
C/20C/10
▲ y = 0,2; ▼ 0,4; ● 0,6; ■ 0,8
26
100 150 200
2,5
3,0
3,5
4,04500C
Vol
tage
, V
Specific capacity, mAh/g50 100 150 200
2,5
3,0
3,5
4,07000C
Vol
tage
, V
Specific capacity, mAh/g
200 nm
450C 700C
Increased ranges of solid solution formation, decreased miscibility gap
200 nm 200 nm
Prepared from FeC2O4
LiFePOLiFePO44: effect of : effect of nanonano--sizing and surface disorderingsizing and surface disordering
N.V. Kosova et al., J. Electrochem. Soc. 157 (2010) A1247-A1252.
27
Mechanism ofMechanism of LiLi deintercalationdeintercalation in in nanonano--sized LiFePOsized LiFePO44
A. Yamada et al., 2001
Solid solutions ranges σ and 1-β increase with reduction of particle size.
Nano-particles
Micro-particles
Full capacity at high rates
Capacity is partially lost
Two-phase mechanism limits phase boundary movement because of low mutual solubility and slow migration of charge carriers.
28
LiFePOLiFePO44: effect of : effect of nanonano--sizing and surface disorderingsizing and surface disordering
200 nm
20 30 40 50 60 70
700C
600C
a=10.315b=6.002c=4.696V=290.74
a=10.320b=6.005c=4.695V=290.94
040,
113,
620
43033
141
2,61
022
2,40
2,23
113
102
2
312,
212
112
102,
221,
401
41012
131
1
301
211,
020
111,
201
01121
010
1
2, degree
200
a=10.323b=6.006c=4.693V=290.95
450C
XRD
-10 -5 0 5 10 15Velocity, mm/s
experiment fit Fe2+ (octa) - 86% Fe3+ (octa) - 14%
700C
600C
experiment fit Fe2+ (octa) - 92% Fe3+ (octa) - 8%
experiment fit Fe2+ (octa) - 74% Fe3+ (octa) - 26%
450C
Mössbauer spectroscopy
N.V. Kosova et al., 16 IMLB, Jeju, Korea, June 17-22, 2012.
29
LiFeLiFe11--yyMnMnyyPOPO44 solid solutionssolid solutions
0.465
0.470
0.475
0.480
0.0 0.2 0.4 0.6 0.8 1.00.595
0.600
0.605
0.610
1.030
1.035
1.040
1.045
1.050 a, Å b, Å
Cel
l par
amet
ers/
nm
y in LiFe1-yMnyPO4
c, Å PDF
3000 2000 1000 0 -1000 -2000 -3000
y = 0
ppm
y = 0,1
y = 0.25
y = 0.5
y = 0.75
y = 1.0
7Li NMR
10000 8000 6000 4000 2000 ppm
y = 0
y = 0.1
y = 0.25
y = 0.5
y = 0.75
y = 1
31P NMR
0,0 0,2 0,4 0,6 0,8 1,0
-40
-20
0
20
40
60
3
4
5
6
7
8
9
10
11
12
Chem
ical shift 31Px10
3/ppm
7Li data of Wilcke our data
Che
mic
al s
hift
7 Li/p
pm
y in LiFe1-yMnyPO4
31P data of Wilcke our data
N.V. Kosova et al., Electrochim. Acta 59 (2012) 404-411.
30
LiFeLiFe11--yyMnMnyyPOPO44: electrochemistry: electrochemistry
2
3
4y = 0
y = 0.1
2
3
4
y = 0.25
y = 0.5
0 50 100 1502
3
4
y = 0.75Pote
ntia
l vs.
(Li/L
i+ )/V
Specific capacity/mAh g-1
0 50 100 150
y = 1.0
2
3
4
2
3
4
2
3
4 0.00 0.25 0.50 0.75 1.00
0
25
50
75
100
125
150
175
theor. Fe3+/Fe2+
exper.
Dis
char
ge c
apac
ity/m
Ah
g-1
y in LiFe1-yMnyPO4
0.00 0.25 0.50 0.75 1.00
0
25
50
75
100
125
150
175
Dis
char
ge c
apac
ity/m
Ah
g-1
y in LiFe1-yMnyPO4
theor. Mn3+/Mn2+
exper.
0.00 0.25 0.50 0.75 1.0025
50
75
100
125
150
175
Dis
char
ge c
apac
ity/m
Ah
g-1
y in LiFe1-yMnyPO4
theor. (total) exper.
31
4 6 8 102degree (
0,143
0,999
0,884
0,38
0,588
char
ge
In situIn situ synchrotron diffraction study of LiFesynchrotron diffraction study of LiFe0.50.5MnMn0.50.5POPO44
N.V. Kosova et al., Solid State Ionics doi:10.1016/j.ssi.2012.01.003
32
In situIn situ synchrotron diffraction study of LiFesynchrotron diffraction study of LiFe0.50.5MnMn0.50.5POPO44
3.75 4.00 4.25 4.50
x=0.21x=0.14
x=0.27x=0.32x=0.38x=0.44x=0.49x=0.60x=0.66x=0.72x=0.77x=0.83x=0.88x=0.94
2, ( = 0.3685 Å)
200 x=1.0
char
ge
3.75 4.00 4.25 4.50
2, ( = 0.3685 Å)
x=0.83
x=0.14x=0.17x=0.26x=0.32x=0.37x=0.43x=0.49x=0.54x=0.60x=0.66x=0.71x=0.77
x=0.88
200 x=0.93
disc
harg
e
0.0 0.2 0.4 0.6 0.8 1.0
4.5
5.0
5.5
6.0
9.5
10.0
10.5
- phase 1 - phase 2
c
b
Cel
l par
amet
er, Å
x in LixFe0.5Mn0.5PO4
acharge
Wide intermediate range of single-phase reaction was revealed.
0.0 0.2 0.4 0.6 0.8 1.0
4.5
5.0
5.5
6.0
9.5
10.0
10.5discharge
x in LixFe0.5Mn0.5PO4
Cel
l par
amet
er, Å - phase 1
- phase 2
c
b
a
0 25 50 75 100 125 1502.0
2.5
3.0
3.5
4.0
4.5
Fe2+ Fe3+
Vol
tage
, V
Specific capacity, mAh/g
Mn2+ Mn3+
Change of the (200) reflection
Change of the (200) reflectionCharge-discharge curves
Cell parameters upon charge and discharge
33
LiLi1.31.3AlAl0.30.3TiTi1.71.7(PO(PO44))33 ((NasiconNasicon) ) –– solid electrolytesolid electrolytea
10 μm
c
10 μm
b
1 μm
d
1 μm
Without MA With MA
MA samples are characterized by:1) lower particle size and larger particle size distribution;2) rounded form of particles instead of cubic form for ceramic samples;3) higher Li surface concentration.
N.V. Kosova et al., Ionics 14 (2008) 303-311.
34
LTP
Ionic conductivity of LTP and LATPIonic conductivity of LTP and LATP
LATP
1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0-7
-6
-5
-4
-3
-2
-1
0
log
(T
[SK
/cm
])
1000/T [K-1]
experiment:high-frequencylow-frequency
fit: bulk grain boundaries total
1,5 2,0 2,5 3,0 3,5 4,0 4,5-5
-4
-3
-2
-1
0
1
log
(T
[SK/
cm])
1000/T [K-1]
experiment:high-frequencylow-frequency
fit: bulk grain boundaries total
1,5 2,0 2,5 3,0 3,5 4,0 4,5-6
-5
-4
-3
-2
-1
0
1
log
(T
[SK
/cm
])
1000/T [K-1]
experiment:high-frequencylow-frequency
fit: bulk grain boundaries total
1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0
-4
-3
-2
-1
0
1
log
(T
[SK
/cm
])
1000/T [K-1]
experiment:high-frequencylow-frequency
fit: bulk grain boundaries total
LTP-MA
LATP-MA
Eb=0.2 eVEb=0.27 eV
Eb=0.23 eVEb=0.22 eV
MA leads to a significant increase (by a factor of a thousand) in grain boundary conductivity of LTP and LATP.
σ = 610-5 Scm-1
at room T
σ = 210-5 Scm-1
at room T
35
NanoNano--micro micro ‘‘corecore--shellshell’’ materialsmaterials
36
NanoNano--micro micro ‘‘corecore--shellshell’’ materialsmaterialscapsulation capsulation
(non(non--conductive conductive coating)coating)
modification modification (diffusion into (diffusion into
the the ‘‘corecore’’))
LiCoOLiCoO22/MO/MOxx LiMnLiMn22OO44/LiMeO/LiMeO22 LiFePOLiFePO44/C/C
Suppression of side reactions with electrolyte,
improved stability to overcharge
Suppression of Mndissolution in electrolyte, acceleration of electron-
Li-ion transport
Increased electronic conductivity
composites composites (conductive coating)(conductive coating)
LiMn2O4
LiMeO2
cryst. С
amorph. С
LiFePO4
MOx
LiCoO2
37
MOx
LiCoO2
10 m 1 m
Surface modification of LiCoOSurface modification of LiCoO22 (Al(Al22OO33))- non-conductive coating - of small thickness (<50 nm)- porous (permeable for electron and Li-ion transport)- prevents side reactions with electrolyte- improves stability to overcharge
N. Kosova et al., Solid State Ionics 179 (2008) 1745-1749.
38
Solution and MA surface modification approachesSolution and MA surface modification approaches
10 m 1 m
10 m 1 m
Sol
MA
39
Electrochemical performance of LiCoOElectrochemical performance of LiCoO22/MO/MOxx
5 10 15 200
50
100
150
200
LiCoO2, initial + Al2O3 + TiO2 + B2O3
+ MgO
Spe
cific
cap
acity
, mA
h/g
Cycle number
Increased discharge capacity due to a higher cut-off voltage (4.5 V) and improved cyclability
80 60 40 20 0 -20 -40 -60 -80
6.2
4.8
55.9
62.1
56.1
61.6 32
.640
.247
.254
.761
.4
ppm
LiCoO2/Al2O3 (80oC)
LiCoO2/Al2O3 (400oC)
LiCoO2/Al2O3 (800oC)
27Al MAS NMR of LiCoO2/Al2O3
N.V. Kosova et al., J. Power Sources 174 (2007) 959-964.
40
LiMnLiMn22OO44/LiMO/LiMO22 (M: Co, Ni, Ni(M: Co, Ni, Ni0.80.8CoCo0.20.2))
InitialInitial LiMnLiMn22OO44
Solution methodSolution method MAMA
200 nm 200 nm
- conductive coating- “reactive” coating- suppresses Mndissolution in electrolyte- accelerates electron/ion transport at SEI
LiMn2O4
LiMeO2
200 nm
41
LiMnLiMn22OO44/LiMeO/LiMeO22: cycling: cycling
0 10 20 30 40 500
25
50
75
100
125
150
4.4 mA
2.2 mA
1.1 mA0.44 mA
0.22 mA
LiMn2O4 initial + LiCoO2 + LiNi0.8Co0.2O2
Spe
cific
dis
char
ge c
apac
ity, m
Ah/
g
Cycle number
Improvement of high-rate performance500600 700
1
2
3
4
ppm
520
526
530
590
** *
6Li MAS NMR of LiMn2O4, surface modified by LiCoO2: 1 – bare, 2 –
annealed at 400C, 3 – 600C, 4 – 750C.
defect spinel
substituted spinel
N.V. Kosova et al., Solid State Ionics 192 (2011) 284-288.
42
XPS study of LiMnXPS study of LiMn22OO44/LiMO/LiMO22
636 638 640 642 644 646 648 650
Mn4+
Mn3+
2
1
XP
S M
n2p 3/
2 In
tens
ity [
arb.
un.
]
Binding Energy [eV]
Mn2p3/2 XPS spectra of pristine LiMn2O4 (1) and LiMn2O4/LiCoO2 (2).
0.016/0.024*0.020/0.021*LiMn2O4/LiNi0.8Co0.2O2
-0.044/0.049*LiMn2O4/LiCoO2
Atomic ratio [Ni]/[Mn]
Atomic ratio [Co]/[Mn]
Core/shell
* after Ar etching
‘Shell’ practically disappears after heat treatment of ground samples at 800C due to the interaction with the ‘core’.
In the case of LiNi0.8Co0.2O2 coating, the surface concentration of Ni is lower than that of Co, probably due to accelerated diffusion of Ni ions into the bulk.
The surface concentration of Mn3+
decreases.
43
CompositeComposite ((nanodomainnanodomain) materials) materials
44
CompositesComposites xLiMnxLiMn22OO44/(1/(1--x)LiCoOx)LiCoO22 ((nanodomainsnanodomains))
LiMn2O4 LiCoO2
1 1 μμmm 1 1 μμmm
1 1 μμmm
MA in high-energy planetary mill followed by heat treatment at 200-400C
45
Composites xLiMnComposites xLiMn22OO44/(1/(1--x)LiCoOx)LiCoO22: cycling: cycling
3.0 3.5 4.0 4.5-5000
0
5000
10000
LiCoO2
3.90
4.15
4.06
4.194.09
3.93
1st cycle 2nd cycle10th cycle
dQ/d
U
Voltage, V3.0 3.5 4.0 4.5
-2000
-1000
0
1000
2000 LiMn2O4
3.96
4.10
4.15
4.03
1st cycle 2nd cycle 10th cycle
dQ/d
U
Voltage, V
N.V. Kosova et al., Russ. J. of Electrochemistry 45 (2009) 277-285.
46
Composites xLiMnComposites xLiMn22OO44/(1/(1--x)LiCoOx)LiCoO22: cycling: cycling
3.0 3.5 4.0 4.5
-1000
0
1000
2000
1st cycle 2nd cycle 10th cycle 3.
98
3.88
4.10
4.03
4.15
3.940.5LiMn2O4/0.5LiCoO2
dQ/d
U
Voltage, V
The redox peaks of LiCoO2 gradually vanished during cycling indicating the occurrence of chemical interaction.
The composites are characterized by good capacity retention (100 mAh/g).
47
Synthesis of the LiFePOSynthesis of the LiFePO44/Li/Li33VV22(PO(PO44))33 compositescomposites
Method A: (one-step) mechanochemically assisted combined CTR synthesis:
Li2CO3 + Fe2O3 + V2O5 + C + (NH4)2HPO4 xLiFePO4 / (1-x)Li3V2(PO4)3
Method B: (two-step) mechanochemically assisted mixing of two individual components:
xLiFePO4 + (1-x)Li3V2(PO4)3 xLiFePO4 / (1-x)Li3V2(PO4)3
N.V. Kosova et al., 63rd Annual Meetinf of ISE, Prague, August 19-24, 2012.
48
LiFePOLiFePO44/Li/Li33VV22(PO(PO44))33: cycling: cycling
Some distinct plateaus are observed on the charge-discharge curves corresponding to two redox pairs: Fe3+/Fe2+ (at 3.4 V) and V3+/V4+ (above 3.4 V).
Low degree of polarization in the cycling curves shows that the electron and ion transport is facile.
As-prepared nanocomposites show excellent stability on cycling.
2.53.03.54.04.5
LFP
Vol
tage
, V
2.53.03.54.04.5
LVP
2.53.03.54.04.5
0.96LFP / 0.04LVP
0 50 100 150
2.53.03.54.04.5
0.5LFP / 0.5LVP
Specific capacity, mA*h/g
-5000
0
5000
Voltage, V
dQ/d
E
3.34
3.46
-2000
-1000
0
1000
2000
3.54
3.63
3.62 3.70
4.03
4.10
-6000-4000-2000
0200040006000
4.04
4.10
3.37
3.48
2.5 3.0 3.5 4.0 4.5-4000
-2000
0
2000
4000
3.613.
483.
543.
63
4.03
3.35
3.70 4.
09
49
ConclusionsConclusions
• Mechanical activation using high-energy planetary mills is a promising solid-state method to prepare nanostructuredelectrode materials for Li-ion batteries
• Mechanical activation allows one to synthesize new composite (‘core-shell’, ‘nano-domain’) materials
• As prepared nanostructured materials differ from bulk materials by morphology, surface/bulk composition and electrochemical properties
• In situ synchrotron diffraction studies evidence the differences in the mechanism of lithium insertion/deinsertion upon cycling of nanostructured and bulk electrode materials
50
AcknowledgementsAcknowledgements
• E.T. Devyatkina - XRD, cycling• V.V. Kaichev - XPS• A.T. Titov - SEM• A.K. Gutakovsky - TEM• A.B. Slobodyuk - NMR• A.P. Stepanov, A.L. Buzlukov - NMR relaxation• D.G. Kellermen - magnetic measurements• S.A. Petrov - Mössbauer spectroscopy• A.S. Ulikhin - impedance spectroscopy• V.V. Ehler, A.V. Markov,
V.K. Makukha - engineering
51
Thank you for your attention!Thank you for your attention!
