All-Hydrocarbon MEA for PEM Water Electrolysis Combining Low Hydrogen Crossover and High Efficiency

Hydrocarbon ionomers bear the potential to significantly lower the material cost and increase the efficiency of proton-exchange membrane water electrolyzers (PEMWE). However, no fully hydrocarbon membrane electrode assembly (MEA) with a performance comparable to Nafion-MEAs has been reported. PEMWE-MEAs are presented comprising sPPS as membrane and electrode binder reaching 3.5 A cm(-2) at 1.8 V and thus clearly outperforming state-of-the-art Nafion-MEAs (N115 as membrane, 1.5 A cm(-2) at 1.8 V) due to a significantly lower high frequency resistance (57 +/- 4 m omega cm(2) vs 161 +/- 7 m omega cm(2)). Additionally, pure sPPS-membranes show a three times lower gas crossover (<0.3 mA cm(-2)) than Nafion N115-membranes (>1.1 mA cm(-2)) in a fully humidified surrogate test. Furthermore, more than 80 h of continuous operation is shown for sPPS-MEAs in a preliminary durability test (constant current hold at 1 A cm(-2) at 80 degrees C). These results rely on the unique transport properties of sulfonated poly(phenylene sulfone) (sPPS) that combines high proton conductivity with low gas crossover.