An overview of oxygen reduction electrocatalysts for rechargeable zinc-air batteries enabled by carbon and carbon composites

Abstract

The merits, such as high specific capacity, less self-discharge and high storage life, make Zinc (Zn)-air batteries promising to serve as energy storage and conversion equipment to effectively solve the energy crisis and environmental pollution caused by the rapid increasing global energy consumption, especially the use of fossil energy. However, the applications and further deployments of the Zn-air batteries depend on costly noble metal as cathodes and are limited by sluggish electrochemical reaction kinetics. As one of the competitive alternatives to noble metals, carbon-based materials such as metal/carbon, nonmetal atom/carbon, metal oxide/carbon and metal-metal oxide-heteroatom/carbon materials exhibit the advantages of structural diversity, high porosity, excellent volume conversion efficiency and non-toxicity. With the emphases on structural improvement and composition optimization, this article summarizes the advances in the development of oxygen reduction reaction (ORR) electrocatalyst based on various carbon contained composites for Zn-air battery cathodes. Furthermore, the challenges and perspectives of the research directions on the Zn-air battery with carbon contained composites as catalyst are discussed in detail.