Bifunctionally active nanosized spinel cobalt nickel sulfides for sustainable secondary zinc–air batteries: examining the effects of compositional tuning on OER and ORR activity

A range of compositionally-tuned nanosized cobalt nickel sulfides ( 125 cycles) and a decent power density of 87 mW cm−2 at 150 mA cm−2 in zinc–air batteries. The electrochemical study of the series of cobalt nickel sulfides made herein suggests that a high electronic conductivity is responsible for the high bifunctional performance, with Ni(III) being identified as a contributor to the OER, while Co(II) and Ni(II) are identified as contributors to the ORR activity. These cathode materials would be highly suitable for safe, sustainable, and long-life zinc–air secondary batteries.