Implanting cation vacancies in Ni-Fe LDHs for efficient oxygen evolution reactions of lithium-oxygen batteries

The main performance limitation of lithium-oxygen (Li-O2) batteries is the formation of the insulating discharge product lithium peroxide (Li2O2), which results in high charging overpotentials and poor cycle stability. Here, Ni-Fe layered double hydroxides (LDHs) with Ni vacancies (Ni-Fe LDHs-VNi) are employed as cathode catalysts for Li-O2 batteries. The battery with Ni-Fe LDHs-VNi cathodes implements excellent performances for the oxygen evolution reaction (OER) process. According to density functional theory (DFT) calculations, the rate determining step of OER processes of Ni-Fe LDHs-VNi is the oxidation process of lithium superoxide (LiO2), and the high adsorption strength towards LiO2 by Ni vacancies lead to a lower charge overpotential than that of pure Ni-Fe LDHs without vacancies. This work provides a strategy to rationally design cathode catalysts with layered structures for high-performance Li-O2 batteries.