Atomic Metal Vacancy Modulation of Single-Atom Dispersed Co/N/C for Highly Efficient and Stable Air Cathode.

Abstract

Metal-air batteries have received great attention as a new energy supply for next-generation electronic devices. However, their widespread application is still hindered by several challenges including sluggish kinetics of the cathodic reactions and undesirable stability of the air cathode due to the possible deposition of the discharge product. Herein, we propose an atomic metal vacancy modulation of a single-atom dispersed Co/N/C cathode to provide the zinc-air battery with both reduced overpotential and enhanced stability. As illustrated by theoretical calculations and electrochemical measurements, deliberate introduction of metal vacancies would modulate the electronic structure and contribute to enhanced catalytic activity, affording the catalyst with a half-wave potential of 0.89 V versus reversible hydrogen electrode and an overall oxygen electrode potential gap of 0.72 V. Moreover, abundant pyridinic-N groups are exposed due to the removal of metal centers, generating strong Lewis basicity to effectively prevent the access of negatively charged zincate ions and realize the nondeposition of ZnO on the air cathode. Rechargeable zinc-air battery assembled with such an air cathode delivers superior cyclic performance with low discharge/charge overpotential and negligible plateau gap increase of only 0.05 V for 1000 cycles. Flexible all-solid-state battery demonstrates robust durability of over 35 h and excellent flexibility to light-up a light-emitting diode (LED) rose, indicating its potential feasibility as a flexible and safe power source for modern life.