Rechargeable Zn-air batteries initiated by nickel-cobalt bimetallic selenide

A Zn-air battery is a potential next-generation energy storage device owing to its extremely high theoretical energy density. Currently, it is important to explore non-precious metal electrocatalysts with high electroactivity and stability in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for the development of Zn-air batteries. In this work, porous (Ni,Co)Se-2 nanosheets were synthesized by selenizing NiCo2O4 nanosheets. By regulating the conductivity and morphology of the sample, the prepared porous (Ni,Co)Se-2 nanosheets show enhanced electrocatalytic activity for OER and ORR compared to NiCo2O4 nanosheets. The aqueous Zn-air battery using porous (Ni,Co)Se 2 nanosheets as the air cathode exhibits superior charge and discharge performance (1.98 V for charging and 1.17 V for discharging), high specific capacity (770 mAh/g), and excellent cycle stability (140 h). These results indicate that the porous (Ni,Co)Se-2 nanosheets are suitable as a bifunctional electrocatalyst for future Zn-air batteries. (C) 2019 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.