Dual-Sites Coordination Engineering of Single Atom Catalysts for Full-Temperature Adaptive Flexible Ultralong-Life Solid-State Zn−Air Batteries

Abstract

High-performance rechargeable Zn-air batteries with long-life stability are desirable for power applications in electric vehicles. The key component of the Zn-air batteries is the bifunctional oxygen electrocatalyst, however, designing a bifunctional oxygen electrocatalyst with high intrinsic reversibility and durability is a challenge. Through density functional theory calculations, it is found that the catalytic activity originated from the electronic and geometric coordination structures synergistic effect of the Fe and Co dual-sites with metal-N<inf>4</inf> coordination environment, assisting the stronger hybridization of electronic orbitals between Co (dxz, dz²) and OO* (px, pz), thus making the stronger O<inf>2</inf> active ability of Co active site. These findings enable to development of a fancy dual single-atom catalyst comprising adjacent Fe-N<inf>4</inf> and Co-N<inf>4</inf> sites on N-doped carbon matrix (FeCo-NC). FeCo-NC exhibits extraordinary bifunctional activities for oxygen reduction and evolution reaction (ORR/OER), which displays high half-wave potential (0.893 V) for the ORR, and low overpotential (343 mV) at 10 mA cm⁻² for the OER. The assembled FeCo-NC air-electrode works well in the flexible solid-state Zn-air battery with a high specific capacity of 747.0 mAh g⁻¹, a long-time stability of more than 400 h (30 °C), and also a superior performance at extreme temperatures (−30 °C–60 °C).