Rational design of carbon-based oxygen electrocatalysts for zinc-air batteries

Zinc-air batteries (ZABs), including traditional aqueous electrolyte-based ZABs and flexible solid-state electrolyte-based ZABs, have been attracting significant attention and receiving intense research efforts recently due to their high energy density, good safety and low cost. As a vital part of the cathode electrode, the bi-functional catalysts promoting the oxygen reduction reaction (ORR) during discharge and oxygen evolution reaction (OER) during recharge, usually have a strong impact on the energy/power density, cycle life and charging efficiency of ZABs. With their cost-effective and unique physiochemical properties, the rationally designed carbon-based oxygen electrocatalysts show conspicuous advantages to the overall performance. This review focuses on the discussion of the up-to-date advances in the design of various carbon-based oxygen electrocatalysts with controlled chemical compositions, tailored shapes, and designed structures for aqueous/solid-state electrolyte-based ZABs. Finally, we describe an overview of the latest achievements and challenges, as well as propose some perspectives on future development trend of bi-functional oxygen electrocatalysts for advanced ZABs.