A novel flow channel design for improving water splitting in anion exchange membrane electrolysers

Anion exchange membrane (AEM) alkaline water electrolysers are a promising reactor in large-scale industrial green hydrogen production. However, the configurations of electrolysers, especially the flow channel, are not well optimised. In this work, we demonstrate that the several existing flow channel designs e.g., single serpentine, parallel, pin can significantly affect the AEM electrolysers' performance. The two-phase flow behaviours associated with the mass transfer of both electrolyte and produced gas bubbles within these flow channels have been simulated and thoroughly studied via a three-dimensional (3D) computational fluid dynamics (CFD) model. A novel flow channel design, named Parpentine, that combines the features of Parallel and Single serpentine designs is proposed with an optimised balance among the electrolyte flow distribution, bubble removal rate, and pressure drop. The superiority of the Parpentine flow channel is well verified in practical AEM water electrolyser experiments, using commercial Ni foam and self-designed efficient NiFe and NiMo electrodes. At a cell voltage of 2.5 V compared to the benchmark serpentine design, a 12.4 % ~ 34.8 % increase in hydrogen production efficiency can be achieved in both 1 M and 5 M KOH conditions at room temperature. This work discovers a novel design and a new method for highly efficient water electrolysers. • The performance of an AEM water electrolyser can be significantly affected by the structure of the flow channels. • A “Parpentine” flow channel is proposed through numerical modelling and design optimisation to achieve a balanced performance in electrolyte flow distribution, bubble removal rate, and pressure drop. • Self-designed NiFe- and NiMo- electrodes are proven efficient for oxygen and hydrogen evolution reactions and are used in an alkaline electrolyser with the proposed flow channel design. • The “Parpentine” flow channel design is proven to maximise the electrolyser's efficiency by up to 34.8 % when compared to the other three existing flow channel designs (e.g., single serpentine, parallel, pin). • It opens a new avenue for AEM water electrolysers optimisation to scale up.