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Development of Nanocomposite Membranes
for
High Pressure PEM Fuel Cell/Electrolyzer Applications
Michael Pien, Marvin Warshay, Steven Lis, Radha JalanElectroChem, Inc 400 W. Cummings Park Woburn, MA 01801
Christine Felice, Deyang Qu Dept of Chemistry, University of Massachusetts Boston, Boston, MA 01225
AIAA
Denver, COAugust 5, 2009
Advance in Polymer Nanocomposites US 2,531,396 1950 Elastomer Reinforced with a
Modified Clay
US 3,084,117 1963 Organoclay Polyolefin Compositions
US 4,739,007 1988 Composite Material and Process for Manufacturing
Clay-based Thin Film as Gas Barrier - Claist
Perfluorinated Sulfonated Polymer as Proto Exchange Membrane
- high temperature fuel cell - direct methanol fuel cell
Structure of Platelets for Barrier
Gallery Height
(exchangeable)
Tetrahedral
Octahedral
Tetrahedral
Different Types of Composites
Conventional Composite
Intercalated Nanocomposite
Exfoliated Nanocomposite
Polymeric Proton Conductive Membrane
O2 H2
e-
H+
Proton Exchange Membrane (PEM)- perfluorinated sulfonate polymer
2 e- + 2 H+
H2O
2 e- + 2 H+
V
Hydrogen Crossover
• Development of mixed potential
• Decrease current efficiency
• Different thermal and water management
• Hot spots
Objectives
• Develop Low H2 Crossover proton conductive polymer membranes for High pressure and Low current density operating electrolyzers
• Retain high proton conductivity of the new membranes
• Investigate the morphology of the new membranes for the reduction of H2 crossover
Selection of Platelets
• Swelling properties
• Capacity of host water and organic molecules
• High cation exchange capacities
• High aspect ratio
• Large surface area
H2 Permeation Evaluation
• Electrochemical method• Limiting current density
H2
Referenceelectrode
Workingelectrode
Counterelectrode
V
H2 N2
H2 = 2 H+ + 2 e-
Conductivity Evaluation
• In-the-plane conductivity - impedance - various humidity and temperature
• Through-the-plane conductivity - impedance
H2 Permeation of the Nanocomposite Membranes
Initial Results of the New Nanocomposite membranes
Membrane wt% clay Thickness10-3 in
H2 crossover
mA/cm2
ConductivitymS/cm
Nafion 211 0 1 0.923 11.9
Nafion 115 0 5 0.385 11.1
Membrane A 10% 1.5 0.385 8.9
Membrane B 10% 3 0.231 8.8
Membrane C 20% 1.5 0.269 5.8
Fuel Cell Evaluation
Membrane D : hot-pressing a Membrane A (10% clay) between two Nafion 212 membranes Membrane F : hot-pressing a Membrane C (20% clay) between two Nafion 212 MembranesThe thickness of membranes D and F is about 5 mils similar to the thickness of Nafion 115 membrane
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.00 0.10 0.20 0.30 0.40 0.50
Voltage, V
H2
cro
sso
ver
curr
ent,
mA
/cm
2
2 mil thick
5 mil thick
Nafion 211
Nafion 212
Nafion 115
Nafion 211
Nafion 115
Nafion 212
5% Clay
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.0 5.0 10.0 15.0 20.0 25.0 30.0
C onduc tivity, mS /c m
H2
Cro
sso
ver
Cu
rren
t, m
A/c
m2
NP 0902-003
NP 0902-004
NP 1001-003
NP 1001-013
NP 05003
NP 05004
NP 1201-002
NP 1203-001
NP 1203-002
NP 1204-004
NP 1201-003
NP 1204-002
NP 1201-004
Which Composite ?
Conventional Composite
Intercalated Nanocomposite
Exfoliated Nanocomposite
Nanocomposite Membranes Optimization
• Selection of materials
• Design of Experiment
Pretreatment
Particle size
Loading
Mixing
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0.0 0.1 0.2 0.3 0.4 0.5 0.6
Voltage, V
H2
cro
sso
ver
curr
ent,
mA
/cm
2
1.5 mils
2.5 mils
4 mils
5% Clay
Methods of Melt Process
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80
Voltage, V
H2
cro
sso
ver
curr
ent,
mA
/cm
2
Mechanical Stir
Sonication
10% Clay
Thickness: 3 mils
Conclusions
• Polymer Nanocomposite based on platelets can reduce the hydrogen permeation
• Polymer nanocomposite membranes can keep good proton conductivity
Future work
• Optimize new polymer nanocomposites based on a Design of Experiment
• New polymer nanocomposites that allow durability characterization
Acknowledgement
This work is funded by
NASA under Contract NNX09CA92C
Electrolyzer Evaluation
0
0.5
1
1.5
2
2.5
0 200 400 600 800 1000 1200
current density, mA/cm2
Cel
l Vo
ltag
e, V
Nafion Clay Composite Membrane Electrochem Supplied JPL Electrolysis MEA Process with Pt cathode /IrO2 anode
70 oC , Ambient Pressure
C onductivity * L imiting C urrent T hickness/A pply C lay(mS/cm) (mA /cm2 ) (mils/coating times) wt%
N P0 9 0 2 -0 0 3 0 .0 8 7 0 .4 6 7 2 .3 / 1 1 0N P0 9 0 2 -0 0 4 0 .0 8 8 0 .1 0 5 5 / 1 1 0N P1 0 0 1 -0 0 3 0 .8 7 6 0 .3 0 7 3 / 1 sonicate 1 0N P1 0 0 1 -0 1 3 0 .5 7 8 0 .6 0 1 2 / 1 1 0N P0 5 0 0 3 5 .5 6 3 0 .5 6 0 2 / 1 1 0N P0 5 0 0 4 7 .2 1 0 0 .2 7 1 4 / 2 1 0N P1 2 0 1 -0 0 2 7 .7 6 0 0 .8 8 2 1 .5 / 1 5N P1 2 0 1 -0 0 3 8 .6 1 1 0 .4 4 3 3 / 3 5N P1 2 0 1 -0 0 4 6 .4 4 5 0 .4 0 0 2 .5 / 2 5N P1 2 0 3 -0 0 1 1 6 .2 6 1 0 .7 4 7 2 / 1 5N P1 2 0 3 -0 0 2 9 .5 5 0 0 .4 1 8 3 .6 / 2 5N P1 2 0 4 -0 0 2 2 5 .6 1 2 0 .5 3 7 2 / 2 5N P1 2 0 4 -0 0 4 1 4 .1 0 5 0 .5 1 9 2 / 2 sonicate 5
Membrane ID Mixing