Electrochemical hydrogen Compression: Module design and membrane development

Electrochemical hydrogen compression (EHC), which can purify and compress hydrogen in one step, has aroused broad interests due to its high efficiency, compact equipment, and quiet operation. Since the concept of EHC was proposed, considerable efforts have been devoted to this field. In this review, several aspects of EHC are comprehensively discussed. Firstly, the working principle of EHC is presented with a focus on the electrode reactions, overpotentials, and performance indicators. Subsequently, the major functions, required properties, common materials and recent progress on the design and development of EHC modules are overviewed. As the key part of EHC, recent advances in proton-conducting membranes are particularly summarized, including polymeric proton exchange membranes, mixed matrix proton exchange membranes, and proton ceramic oxide membranes. The focus is on the chemical structures, proton transfer mechanisms, factors affecting performances, and applications for hydrogen purification and compression. Finally, the challenges, future trends, and prospects associated with each module of EHC are discussed.