Scheelite ZnMoO4 cathode catalyst boosts the cycle durability at a wide range temperature of Li-O2 batteries through crystal structure rearrangement by oxygen vacancy

Abstract

Lithium-oxygen batteries (LOBs) have received intense attention due to their ultra-high energy density. However, the major impediments of LOBs, including poor cycle stability, sluggish reaction kinetics, and high overpotentials, are mainly derived from unreliable cathode catalysts. Unfortunately, most of the batteries only exhibit satisfactory performance at room temperature conditions; finding better catalysts that work in sub-ambient temperatures remains a challenge. In this study, a scheelite ZnMoO₄ catalyst was reported which can stably work over 580 cycles at room temperature and 297 cycles at sub-ambient temperatures (10 °C). The experimental and theoretical investigation demonstrated that the oxygen vacancies cause structural rearrangement to form pentahedrons in the scheelite structure, which is conducive to surface metal ion exposure, strong adsorption ability, and high electron transfer efficiency, which is beneficial to stabilize the LiO₂ and the surface formation route of Li₂O₂. This work provides a novel strategy for the design of cathode catalysts for LOBs at a wide range of temperatures.