Synergistic regulation of nickel doping/hierarchical structure in cobalt sulfide for high performance zinc-air battery

Reduced-graphene-nanoribbon supported nickel doped Co9S8 spheres (Ni-Co9S8/rGN) have been successfully constructed. The hierarchical structured sphere assembles by spindle-type nanorods features high surface area and good hydrophilicity property. Excellent OER/ORR activities and long-term stabilities are obtained on NiCo9S8/rGN relative to Pt/C and RuO2. Density functional theory calculations demonstrate that nickel dopants in Co9S8 structure effectively optimizes the adsorption properties at the rate-determining steps. Therefore, the synergistic regulation between the rGN covered hierarchical structure and nickel dopants by promoting the intrinsic ORR/OER properties, electrical conductivity, and mass transfer is responsible to the superior catalytic performance. Moreover, as a bi-functional catalyst for liquid and flexible Zn-air batteries, Ni-Co9S8/rGN based battery exhibits excellent battery performance, especially high power density, superior rate performance and long-term cycling stability, providing a new vision for the preparation of high-efficiency catalysts in energy conversion.

Automated summary

The Ni-Co9S8/rGN composite material with a hierarchical sphere structure exhibits high surface area and excellent hydrophilicity, leading to superior activity and stability in oxygen reduction and oxygen evolution reactions. Nickel doping in Co9S8 structure effectively optimizes adsorption properties and plays a crucial role in electrocatalytic performance.