Elucidating the performance limitations of a 25 cm2 pure-water-fed non-precious metal anion exchange membrane electrolyzer cell

Abstract

Anion exchange membrane (AEM) water electrolysis has emerged as a promising technology for producing hydrogen in a carbon-neutral economy. To advance its industrial application, performance evaluations of non-precious metal AEM electrolyzers with electrode areas of 25 cm2 were conducted. The focus was on pure water operation, achieving a current density of 0.26 A cm−2 at a voltage of 2.2 V. To gain a better understanding, the AEM electrolyzer was also operated in aqueous KOH, yielding 1.2 A cm−2 at 2.2 V. By adding a liquid electrolyte and by varying cell components, causes of the occurring performance limitations and ways to improve the AEM electrolyzer were identified. Electrochemical impedance analysis showed that the activation loss at the anode due to sluggish OER kinetics was the limiting factor at low current densities. At higher current densities, which is the operating range of interest for industrial application, the ohmic resistance from the membrane was the dominant factor limiting high performance in pure water operation.