Technical factors affecting the performance of anion exchange membrane water electrolyzer

Abstract

Anion exchange membrane (AEM) electrolysis is a promising membrane-based green hydrogen production technology. However, AEM electrolysis still remains in its infancy, and the performance of AEM electrolyzers is far behind that of well-developed alkaline and proton exchange membrane electrolyzers. Therefore, breaking through the technical barriers of AEM electrolyzers is critical. On the basis of the analysis of the electrochemical performance tested in a single cell, electrochemical impedance spectroscopy, and the number of active sites, we evaluated the main technical factors that affect AEM electrolyzers. These factors included catalyst layer manufacturing (e.g., catalyst, carbon black, and anionic ionomer) loadings, membrane electrode assembly, and testing conditions (e.g., the KOH concentration in the electrolyte, electrolyte feeding mode, and operating temperature). The underlying mechanisms of the effects of these factors on AEM electrolyzer performance were also revealed. The irreversible voltage loss in the AEM electrolyzer was concluded to be mainly associated with the kinetics of the electrode reaction and the transport of electrons, ions, and gas-phase products involved in electrolysis. Based on the study results, the performance and stability of AEM electrolyzers were significantly improved.