Formation of sandwiched leaf-like CNTs-Co/ZnCo2O4@NC-CNTs nanohybrids for high-power-density rechargeable Zn-air batteries

Air cathodes with high-efficiency oxygen reduction and evolution reaction (ORR/OER) performances are essential but still challenging for the development of high-power-density rechargeable Zn-air batteries. We herein report the preparation of a bifunctional oxygen electrocatalyst, composed of Co/ZnCo2O4 nanoparticles sandwiched in leaf-like nitrogen-doped carbon microplates interwoven with carbon nanotubes (denoted as Co/ ZnCo2O4@NC-CNTs). Owing to large amount of metal-Nx and Co3+ active sites as well as the interwove CNTs on the surface of carbon microplates, the Co/ZnCo2O4@NC-CNTs catalyst reveals excellent ORR/OER activities manifested as a small potential gap (Delta E = 0.70 V), a superior high-power density of 305 mW cm(-2) and a stable rechargeability of up to 103 h with the Zn-air battery. Meanwhile, the Co/ZnCo2O4@NC-CNTs-based flexible solid-state Zn-air battery also exhibits competitive peak power density (151 mW cm(-2)), robust flexibility and integrability.

Automated summary

The study introduces a bifunctional oxygen electrocatalyst, Co/ZnCo2O4@NC-CNTs, with high efficiency in oxygen reduction and evolution reactions for Zn-air batteries. This catalyst shows excellent performance in Zn-air batteries, providing a small potential gap, high power density, and long cycle life. Additionally, it can be used in flexible solid-state Zn-air batteries and exhibits competitive performance.