WIR SCHAFFEN WISSEN – HEUTE FÜR MORGEN Membranes for Water Electrolysis - Target-Oriented Choice and Design of Materials Lorenz Gubler :: Paul Scherrer Institut Durability and Degradation Issues in PEM Electrolysis Cells and its Components February 16, 2016 :: Fraunhofer ISE, Freiburg, Germany
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WIR SCHAFFEN WISSEN – HEUTE FÜR MORGEN
Membranes for Water Electrolysis -Target-Oriented Choice and Design of Materials
Lorenz Gubler :: Paul Scherrer Institut
Durability and Degradation Issues in PEM Electrolysis Cells and its ComponentsFebruary 16, 2016 :: Fraunhofer ISE, Freiburg, Germany
Page 2
Acknowledgement
The research leading to these results has received funding from the European Union's Seventh Framework Programme(FP7/2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement n°303484.
NorwaySintef
United KingdomJohnson Matthey Fuel CellsTeer Coatings
FranceAreva H2GenCEA
GermanyFraunhofer ISE
SwitzerlandPSI
Page 3
Table of Contents
Durability Aspects
Introduction
A simple performance model Resistance - gas crossover tradeoff Membrane development within
NOVEL
Selection Criteria for Membranes
Radical-induced degradation Thermal stress test
Loss terms in PEM electrolysis
Conclusion
Page 4
Loss Terms in PEM Electrolysis
K. Ayers et al., ECS Trans. 33/1 (2010) 3
slope:0.23 ∙cm2
(~Nafion 117)
Ohmic (mainly membrane) lossesdominate at high current density
1 M. Schalenbach et al., J. Phys. Chem. C 119 (2015) 251452 T. Sakai et al., J. Electrochem. Soc. 132 (1985) 13283 Z. Zhang et al., J. Membr. Sci. 472 (2014) 554 fit of H2 crossover data
P(H2) ≈ 2P(O2)
4 O2inH2
Membrane Thickness / m0 50 100 150 200
i min fo
r 2%
H2 i
n O
2 /
A·c
m-2
0.1
1
10
1 bar10 bar100 bar
i @ 2.0 V
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Operational Range (Turndown Ratio)
Cur
rent
Den
sity
/
A·c
m-2
0
1
2
3
4
5
6
7
8
Membrane Thickness / m200 60 25
p = 20 baraimax = i @ 2.0V
imin = limit of 2% H2 in O2*(proportional to p !)
0.87
2.35
7.55
2.90
6.95
Operational range with thinmembranes is limited due tocrossover issue→ Need to increase gas barrierproperties of membrane
5.20
* ~equivalent to 0.5% O2 in H2
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Area Resistance / m·cm2
0 50 100 150 200 250
H2 C
ross
over
/ m
A·c
m-2
0
1
2
3
4
5
Membrane Development Strategies
Nafionmembranes
80C, 100% r.h., 2.5 bara1. PFSA membranes
improve gas barrier properties
2. Alternative membraneschoose materials with intrinsicallybetter combination of resistanceand gas permeability