A dual-layer flow field design capable of enhancing bubble self-pumping and its application in water electrolyzer

Abstract

The conventional flow-field configurations such as parallel and serpentine flow fields in proton exchange membrane water electrolyzer have encountered serious bubble accumulation phenomena in channels, blocking the water delivery to the electrode and creating a large mass-transfer resistance. Therefore, we propose a dual-layer flow field design. Specifically, the degassing layer is tightly installed on the base layer, forming a dual-layer configuration, capable of enhancing the self-pumping effect (bubbles automatically detach from the outer surface of the electrode) due to the formation of capillary pressure difference between the upper and lower surfaces of bubbles. Firstly, we theoretically analyze the feasibility of this dual-layer design through numerical simulation. The results show that the bubbles in the channel will be sucked into the degassing layer from the base layer, thus creating more space for water supply to the electrodes, which is further verified by in-situ visualization. Finally, it is found that an introduction of the degassing layer significantly upgrades the cell performance (approximately 0.15 V at 5.0 A cm−2) compared with conventional single-layer design. Therefore, this study provides insights for future flow-field design in high-performance water electrolyzers.