Performance and Durability of Anion Exchange Membrane Water Electrolyzers using Down-selected Polymer Electrolytes

Over the last decade, several stable anion exchange polymer electrolytes have been developed for electrochemical devices. Herein, we investigate how the chemical structure and physical properties of polymer electrolytes affect performance and durability of anion exchange membrane water electrolyzers (AEMWEs). We select polymer electrolytes with high alkaline stability and consider their polymer properties including conductivity, mechanical/chemical stability, and material interactions to interpret the performance and durability of AEMWEs. The AEMWE with a poly(phenylene) membrane and a poly(fluorene) ionomeric binder exhibited the best performance among those tested in this study; the AEMWE showed ~1 A cm-2 at 2 V under 1 wt% K2CO3-fed conditions. The voltage degradation rate was 270 - 550 μV h-1 for several hundred operating hours at a constant current density of 750 mA cm-2 and a differential pressure of 100 pounds per square inch gauge. Based on these results, we discuss the research needs of polymer electrolytes for practical AEMWEs.