Water electrolysis technologies: the importance of new cell designs and fundamental modelling to guide industrial-scale development

Abstract

Large-scale, sustainable, low-cost production of hydrogen can reduce the negative effects of climate change by decarbonising energy infrastructure. Low-carbon hydrogen can be synthesised via water electrolysis. Today, however, this only constitutes a minor proportion of global hydrogen production, as fossil fuel-based processes are used predominantly with large amounts of carbon emissions. Low-temperature electrolysis (< 100 ºC) has garnered significant attention, due to lower capital cost and operational complexity than high-temperature electrolysis (> 700 ºC). In this review, the latest advancements in low-temperature water electrolysers are provided from the current-generation, membrane-based designs to the next-generation membrane-less designs. The coverage of electrodes by gas bubbles can cause a drastic loss in their activity and, hence, the hydrogen production efficiency of the device. To alleviate this issue, aerophobic and aerophilic electrodes are being developed. Their advantageous properties are discussed. Furthermore, models of water electrolysers are reviewed to provide critical understanding of the different parameters affecting the electrochemical performance of these devices. Finally, an industrial perspective is given to discuss the challenges in large-scale Gigawatt-level deployment of these devices in coming decades to meet future green hydrogen demand.