Capillary-Fed Zero-Gap Water Electrolyser

Abstract

A transition towards renewable energy sources is necessary to globally achieve net-zero carbon emissions. To achieve reliable renewable energy production, storage of sustainable energy is key. The utilisation of hydrogen, whether for long-term or short-term storage, could provide a vital solution in achieving reliability for sustainable energy demand. However, producing green hydrogen (water electrolysis) is not cost-competitive with fossil fuels and other hydrogen production methods. An original alkaline electrolyser design has been created that can help with lowering the CAPEX and OPEX when optimized. In common alkaline electrolysers, electrodes are completely immersed in liquid. However, the electrode surfaces of the novel design apply wetted surfaces through the use of capillary forces to suck up electrolytes. Compared to immersed electrode surfaces, the wetted surface shows a reduction in (bubble) resistance leading to lower voltage losses. Additionally, the overpotential can be further reduced with, for example, the use of a PES membrane instead of a common Zirfon membrane, better contact with the anode by welding it to the current collector, and adding PTFE to the anode for better gas removal. Prior to testing the assembled cell design, the electrodes were tested individually to understand the mechanics of each electrode. Here, we report that the electrodes perform well individually in alkaline media.
However, our findings reveal that the assembled cell performs poorly, mostly because of significant overpotentials brought on by increasing resistance, along with other drawbacks including salt formation and exceeding the legal gas crossover limit. Some of these issues regarding performance are still poorly understood and therefore need further investigation.