The effect of membrane on an alkaline water electrolyzer

Water electrolyzers are being developed as a way of storing renewable energy, as a way to produce hydrogen for fuel cell automobiles, and as a route to renewable fuels and chemicals. In this paper the performance of an alkaline water electrolyzers at 60 °C with 1 M KOH and iron/nickel/cobalt catalysts with several different membranes: Sustainion® 37–50, Fumasep FAS-50, Fumasep FAPQ, Neosepta ACM, AMI 7001, Nafion® 115, and Celazole® PBI. Measured area specific resistances (ASR) at 60 °C with 1 M KOH varied from 0.045 Ω-cm2 with Sustainion® 37–60 to over 50 Ω-cm2 with Neosepta ACM. The current at a cell potential of 1.9 V varied from 1 A/cm2 with Sustainion® 37, 0.5 A/cm2 with Fumasep FAS-50, 0.17 A/cm2 with Fumasep FAPQ and less than 0.1 A/cm2 for Neosepta ACM, AMI 7001, Nafion 115 and Celazole® PBI. Constant current runs at 1 A/cm2 were done with the Sustainion® 37 membranes and the Fumasep FAS-50. The cell with the Sustainion® 37 membrane was very stable. The voltage to maintain 1 A/cm2 rose only 3–5 μV/h over a 2000 hr run. In contrast, the voltage to maintain 1 A/cm2 in the cell with the FAS-50 membrane showed over 200 μV/h increase and failed after 200 h. One Sentence Summary: The paper shows that one can double the current output of an alkaline water electrolyzer by using Sustainion® 37 membranes.