Enhancing water and oxygen transport through electrode engineering for AEM water electrolyzers

Anion-exchange membrane water electrolyzers (AEMWEs) potentially combine the benefits of low cost and high efficiencies from incumbent water electrolysis technologies. While tremendous efforts have been made in advancing material properties (e.g., developing novel catalyst materials or polymer membranes), large-scale deployment of AEMWEs for hydrogen production has not been achieved, primarily due to performance and durability limitations, especially under industrially relevant conditions (such as at high current and dry-cathode operations). This study investigates sources of efficiency loss and identifies the critical role of water back-diffusion in affecting species transport and electrode kinetics under representative electrode architectures and feeding configurations. The experimental observations are complemented with extensive in situ and operando characterizations. To achieve scalable fabrication of electrodes with enhanced transport features, a key additive is selected to fine tune ink properties. By doing so, the correlation among catalyst ink rheology, electrode structure, and AEWME performance can be established and demonstrated in this study. Our rational electrode design strategy allows for drastic improvement in AEMWE efficiency and durability.