“Coupling-conversion” effect induced by interface-local electric field to improve oxygen reaction kinetics in zinc-air batteries

Abstract

Practical application of rechargeable zinc-air batteries is restricted by slow oxygen reaction kinetics of their bifunctional catalysts. This study is based on the ability of interface-localized electric fields to enhance charge transfer and accelerate electrochemical reactions. Fe and VN metal clusters formed on the foam carbon were used to form local electric field-orientated heterogeneous interfaces, which exhibited effective adsorption and catalytic performance for ORR/OER. Theoretical simulations and ultraviolet photoelectron spectroscopy analysis have confirmed that an interface electric field close to the Fermi level can improve the electronic structure of metals, enhancing their adsorption/desorption performance in ORR and OER. The resulting FeACs-VNNCs (1:1)/NFC material exhibited “coupling-conversion” effect and demonstrated outstanding bifunctional ORR/OER activity (E1/2 = 0.87 V, Ej=10 = 1.476 V). The rechargeable zinc-air battery, assembled using the newly prepared catalyst, displayed a high specific capacity of 779 mAh g−1 and was stable after 3104 operation cycles. The study substantiates the possibility of ion diffusion and charge transfer acceleration by interface-localized electric fields induced in zinc-air battery electrodes.