Quantifying Sources of Voltage Decay in Long-Term Durability Testing for PEM Water Electrolysis: Article No. 054508

Meeting a competitive 1$/kg hydrogen cost target for polymer electrolyte membrane water electrolysis (PEMWE) will require advances to significantly reduce capital costs and precious metal catalyst usage, while simultaneously enabling 40,000-80,000 h stack lifetimes under dynamic use conditions. Minimizing cell voltage decay rates is therefore a key goal for PEMWE, although the fundamental processes governing voltage decay are not yet well understood. Here we present a quantitative approach to analyze the contributions to voltage decay in long-term PEMWE testing using polarization curves, impedance spectroscopy, and post-mortem electron microscopy. We apply this approach to analyze a 28 ..mu..V h-1 decay rate observed in a 4000 h durability test of a cell using 0.5 mg cm-2 total PGM catalyst loading (0.4 mgIr cm-2 anode, 0.1 mgPt cm-2 cathode) and 3 A cm-2 current density. We also analyze a comparative series of 1000 h tests under different conditions. These results provide valuable insights into anode catalyst degradation processes, as well as transferrable methodology for PEMWE durability research.