Highly Stabilized Zinc-Air Batteries Based on Nanostructured Co3O4 Composites as Efficient Bifunctional Electrocatalyst

Zinc-air batteries are expected to be ideal energy storage devices, showing features of high energy density, economic viability, and safety. To design such a system, it is necessary to develop active and durable electrocatalysts to catalyze the slow oxygen reduction reaction (ORR) during discharging and the oxygen evolution reaction (OER) during charging. In this study, a composite bifunctional catalyst (Co3O4@CNT@MC-200) for use in zinc-air batteries is prepared through a simple sol-gel method, which combines Co3O4 with carbon nanotubes (CNTs) and mesoporous carbon (MC). Benefiting from its large specific surface area and, thus, a multitude of active sites, the Co3O4@CNT@MC-200 composite bifunctional electrocatalyst shows excellent ORR performance in 0.1 M KOH, resulting in a half-wave potential (E1/2) of 0.72 V and limiting diffusion current of 4.6 mAcm(-2). In zinc-air battery tests, a high discharge peak power density of 267 mW cm(-2) and robust lifetime of 8700 min without attenuation is observed. Moreover, the physical properties of the reported catalyst were characterized. This study allows us to envisage the design of highly efficient composite electrocatalysts for zinc-air batteries and a variety of other energy applications.