Zinc regeneration in rechargeable zinc-air fuel cells-A review

•Zinc-air fuel cells/batteries are promising as energy source for numerous applications.•Efficient regeneration of zinc is a corner stone for such cells.•A comprehensive review is presented on developments in the field over the last decade.•Electrode materials, electrode and electrolyte additives are carefully considered.•Related technological challenges and their possible solutions are also considered.

Zinc-air fuel cells (ZAFCs) present a promising energy source with a competing potential with the lithium-ion battery and even with proton-exchange membrane fuel cells (PEMFCs) for applications in next generation electrified transport and energy storage. The regeneration of zinc is essential for developing the next-generation, i.e., electrochemically rechargeable ZAFCs. This review aims to provide a comprehensive view on both theoretical and industrial platforms already built hitherto, with focus on electrode materials, electrode and electrolyte additives, solution chemistry, zinc deposition reaction mechanisms and kinetics, and electrochemical zinc regeneration systems. The related technological challenges and their possible solutions are described and discussed. A summary of important R&D patents published within the recent 10 years is also presented.