Recent advances in solid-state metal-air batteries

Solid-state metal-air batteries have emerged as a research hotspot due to their high energy density and high safety. Moreover, side reactions caused by infiltrated gases (O-2, H2O, or CO2) and safety issues caused by liquid electrolyte leakage will be eliminated radically. However, the solid-state metal-air battery is still in its infancy, and many thorny problems still need to be solved, such as the large resistance of the metal/electrolyte interface and catalyst design. This review will summarize some important progress and key issues for solid-state metal-air batteries, especially the lithium-, sodium-, and zinc-based metal-air batteries, clarify some core issues, and forecast the future direction of the solid-state metal-air batteries.