Carbon-based cathode materials for rechargeable zinc-air batteries: From current collectors to bifunctional integrated air electrodes

Rechargeable zinc-air batteries (ZABs) have attracted much attention as the next-generation energy conversion and storage devices due to the abundance and environmental friendliness of zinc (Zn) for anode materials, as well as the safety and low cost of aqueous electrolytes. However, rational design of nonprecious and low-cost integrated air cathode materials with a desirable bifunctional oxygen electrocatalytic performance remains a great challenge for the commercialization of rechargeable ZABs. In previous research studies, various cost-effective carbon-supported electrocatalysts and light-weight carbon-based current collectors for air cathodes have been developed, showing vast potential in the application of carbon-based materials. To improve the bifunctional performance and integration of air cathodes, efforts with respect to the design of morphology, defects, and synergistic effects of carbon-based materials have been made. In this perspective, the general understanding of the air cathode construction and the battery working mechanism is discussed. The recent progress in the design of carbon-based materials for air cathodes in rechargeable ZABs is summarized. Several possible future research directions and the expected development trends are also discussed, aiming to facilitate the commercialization of advanced rechargeable ZABs in our life.