Coupling interfaces between hollow carbon dodecahedrons and layered double hydroxides for high-performance rechargeable zinc−air batteries

Abstract

The rational design of high-performance bifunctional electrocatalysts toward both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critical for the development of high-efficiency zinc−air batteries (ZABs). Herein, we report a facile method to synthesize a bifunctional electrocatalyst (FeNC/LDHs), which consists of Fe-doped hollow carbon dodecahedron (FeNC) coupling with NiFe-layered double hydroxides (LDHs). The coupling integration of FeNC dodecahedra and LDH nanosheets enriches the electrochemically active surface area and modulates the electron redistribution via oxygen bridges between FeNC and LDHs, thus effectively improving electrocatalytic activity and exhibiting a small potential difference of ΔE = 0.68 V during the ORR and OER process. The optimized FeNC/LDH-21 as a cathode in zinc-air batteries demonstrates a specific capacity of 810 mAh·g−1 at 10 mA·cm−2 and a power density of 85 mW·cm−2, and stable operation over 160 h. Moreover, the as-assembled solid-state flexible ZAB reaches a power density of 32.4 mW·cm−2 and maintains a stable charge-discharge process at different bending or hammering states. This work opens an avenue for the facile and large-scale synthesis of bifunctional electrocatalysts and would propel the practical application of ZABs.