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

Abstract

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/ZnCo 2 O 4 nanoparticles sandwiched in leaf-like nitrogen-doped carbon microplates interwoven with carbon nanotubes (denoted as Co/ZnCo 2 O 4 @NC-CNTs). Owing to large amount of metal-N x and Co 3+ active sites as well as the interwove CNTs on the surface of carbon microplates, the Co/ZnCo 2 O 4 @NC-CNTs catalyst reveals excellent ORR/OER activities manifested as a small potential gap (ΔE = 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/ZnCo 2 O 4 @NC-CNTs-based flexible solid-state Zn-air battery also exhibits competitive peak power density (151 mW cm −2 ), robust flexibility and integrability. A sandwiched leaf-like bifunctional CNTs-Co/ZnCo 2 O 4 @NC-CNTs electrocatalyst was designed and synthesized, which exhibits a superior high-power density of 305 mW cm −2 and a stable rechargeability of up to 103 h with the Zn-air battery. • Co/ZnCo 2 O 4 nanoparticles sandwiched in leaf-like N-doped carbon microplates interwoven with CNTs is synthesized. • Large amount of metal-N x and Co 3+ active sites can be obtained in the final product. • The catalyst exhibits excellent bifunctional catalytic activities for ORR and OER with a small potential gap (ΔE = 0.70 V). • The assembled Zn-air battery exhibits superior high-power density of 305 mW cm −2 and stable rechargeability of up to 103 h.