Novel gas separation membranes for alkaline water electrolysis

摘要

Hydrogen production via water electrolysis is regaining attention in the global search for alternative energy carriers nowadays. Efficiency enhancement in alkaline electrolysis to reduce the electric power consumption is a pre-condition for a successful application of this promising technology. Within the EU project ELYGRID, several approaches have been applied to improve the efficiency of alkaline electrolysers. The process has been optimized to reduce the surface-specific cell resistance during operation at increased current densities (zero-gap cells, low-resistance membranes). The operating temperatures have been increased to increase the electrolyte conductivity and to decrease electrode overpotentials, and new electrocatalysts have been introduced to reduce anodic and cathodic overpotentials. The membrane, which separates hydrogen and oxygen gases during the electrolysis process, is a crucial part of the electrolyser cell. Besides that, the membrane has to ensure high ionic conductivity and feature an excellent chemical stability in 30 wt% KOH up to 120°C and 30 bar for long term operation over several years. Novel membranes with promising characteristics for low resistance diaphragms have been developed and the results will be presented below.