A comprehensive review of metal-air batteries: Mechanistic aspects, advantages and challenges

The pursuit of higher energy density for electrochemical energy storage systems has directed attention towards rechargeable metal-air battery chemistries, all of which function based on reversible oxygen redox, i.e., oxygen evolution and reduction reactions. This renders electrocatalyst an essential functional component, with the design/development of efficient-cum-stable electrocatalysts assuming enormous importance. However, these battery chemistries have challenges, such as the passivation of catalysts and dendrite growth at the metal anode. In this regard, after introducing the mechanistic aspects of metal-air battery chemistry, in general, the review discusses the chemistries in more specific terms, followed by highlighting the challenges and ways adopted to address them.