Compositing doped-carbon with metals, non-metals, metal oxides, metal nitrides and other materials to form bifunctional electrocatalysts to enhance metal-air battery oxygen reduction and evolution reactions

Rechargeable metal-air batteries (MABs) have gained renewed attention because of their feasibility as electrochemical energy storage/conversion devices. Although MABs possess drastically higher theoretical energy densities than traditional aqueous or lithium-ion batteries, the development and commercialization of MABs have been challenged considerably due to the lack of efficient and robust air-electrode electrocatalysts which are used for both oxygen reduction reactions (ORR) and oxygen evolution reactions (OER). To improve the bifunctional activity and stability of these electrocatalysts, doped-carbon composite catalysts have been explored as one type of modified electrode and have demonstrated great potential toward MAB applications due to the synergistic interactions between the dopant(s), carbon, and other noncarbon component(s). This article reviews the progresses and advancements in the development of various doped-carbon composite bifunctional catalysts for MAB cathodes with an emphasis on material selection, structural characterization and electrochemical properties, as well as their applications in MABs. This review provides developmental details that will benefit readers from both academia and industry.Peer reviewed: YesNRC publication: Ye