IMPACT progress meeting , Messina Matthias Schätzle, Florian Wilhelm, Joachim Scholta Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW) WP h durability test

h durability test  200 h durability test conducted twice 1.Single cell test (100 cm²) 2.Three-cell rainbow stack (100 cm²) Cell 1  commercial MEA (A) Cell 2  JMFC Cell 3  commercial MEA (B)  GDL SGL 25BC IMPACT baseline material in all cases  Tests performed on different test benches ParameterAnodeCathodeStack Temperature [°C]85 80 Dew point [°C] RH [%] Stoichiometrie1.52- Pressure outlet [bar]1.5 -

- 3 - Flow configuration counter-flow for both test set up the same

h durability single cell test result Single cell test Ophour 125 test bench shutdown 2 hours  Reversible degradation observed Single cell test Ophour 175 test bench shutdown 6 hours  Reversible degradation observed 1.15 mV/h Overall degradation 0.94 mV/h

h durability single cell and rainbow test overview Rainbow stack Ophour 180 test bench shutdown (1 hours) Restart with T-Stack 73°C Rainbow stack Ophour 195 T-Stack 80°C and load cycling

- 6 - Load cycle at constant mass flow (OpHour 195)

- 7 - Pol curves ID cell rainbow stack BOL

- 8 - Pol curves rainbow stack (ID0831) BOL + 200h

- 9 - Pol curves ID0831 BOL + 200h + 2 weeks break  Cells 1 and 3 almost recovered to voltage level of BOL  Cell 2 (JMFC) dramatic performance loss

CV-Measurement Cathode (Zahner IM6) Operating conditions: Emin = 0.08 V Emax = 1.2 V Slewrate = 20 mV/s Stack  Impact durability test H 2 -Adsorption  Integral is equal to active platinum surface area

CV-Measurement Cathode  First column represents BOL  Second column represents measurement after 200 Ophours and 2 weeks break Loss of >50%

EIS-Measurement of cell 2 rainbow stack 7.15 Hz 30 kHz0.1 Hz

Replacement of cell No two (JMFC)  Cell two replaced by a new MEA  Most likely JMFC MEA holds a water management problem  rather too much water  New tests started with lower gas humidification  Aim of the next tests were discover sensitivity of gas humidification  Additionally flow configuration was changed to Co-Flow

Flow Configuration changed Co-Flow (gases top to bottom)

Test overview new rainbow stack only cell 2 (JM) replaced  JMFC cells is not effected by changing humidification on cathode or anode  Continuous degradation Ophour 20 DPT A from 64°C to 75°C Comm. MEAs increase by mV JMFC drops 60 mV

© 2013 Solvay Specialty Polymers Durability Solvay 200 h 500 h Visible strong decay but loss is partially reversible after shut-down or “spontaneously”. Maybe observed behavior related to gas quality, further investigation planned at SLX 1.0 A/cm2 (25 A), 80/64/64, 1.5 bara, stoic 1.5/2

Cathode catalyst cleaning procedure 1.OCV and air is replaced by nitrogen 2.Set load to 60 Amps for approx. 30 sec 3.Back to OCV and nitrogen is replaced by air 4.Back to “normal operation” at 60 Amps

Load cycle at constant mass flow  Same reaction of the cell voltage  Final proof to be sure that this phenomenon is due to flooding

Comparison between Solvay and ZSW BOL 500 h © 2013 Solvay Specialty Polymers 19  Difference of performance BOL of approx. 30 mV between Solvay and ZSW  Degradation rate at ZSW three times higher  ZSW (0.94 mV/h) Solvay (0.35 mV/h) ZSW BOL ZSW 200h

Conclusion  High degradation rate of JMFC MEA is reproducible  different test benches  different institutes  different cell designs (ZSW 100cm² / Solvay 25 cm²)  Mainly it is due to high loss of active platinum surface area  reason finally not clarified  post mortem analysis  In addition by a water management issue  reversible degradation (load cycling)  Membrane resistance kept constant over durability test  flooding phenomenon occurs in the electrode or GDL  No operating conditions for steady state point were found

Thank you for your attention!

Backup slides  Backup slides are following…

Comparison of EIS-Measurements cell 2 rainbow stack and single cell test

NEDC

© 2013 Solvay Specialty Polymers 25 BOL Characterization – 80/64/64* * Tcell / Tdew An / Tdew Cat © 2013 Solvay Specialty Polymers 25

 EOL characterization confirms the decay of performance observed in the durability test  The main cause of decay is related to a loss of catalyst activity whereas the membrane does not show an increase of resistivity.  The loss of activity could be caused by catalyst degradation but also from poisoning effects (gas quality?) EOL Characterization © 2013 Solvay Specialty Polymers 26