Single-Atom Immobilization Boosting Oxygen Redox Kinetics of High-Entropy Perovskite Oxide Toward High-Performance Lithium-Oxygen Batteries

Abstract

Understanding and modulating the unique electronic interaction between single-metal atoms and high entropy compounds are of great significance to enable their high-efficiency oxygen electrocatalysis for aprotic lithium-oxygen (Li-O₂) batteries. Herein, a novel bi-functional electrocatalyst is for the first time created by immobilizing single-atom ruthenium (Ru) on lanthanum-based high entropy perovskite oxide La(Mn_0.2Co_0.2Fe_0.2Ni_0.2Cr_0.2)O₃ (Ru@HEPO), which demonstrates high activity and stability in Li-O₂ batteries. The heteronuclear coordination between single-atom Ru and HEPO facilitates fast electron transfer from Ru to HEPO by establishing Ru-O-M (M stands for Mn, Co, Fe, Ni) bridges, which well redistributes electrons within the Ru@HEPO hence significantly improving its interfacial charge transfer kinetics and electrocatalytic activity. Additionally, the strong electron coupling between Ru and Mn atoms enhances the hybridization between Mn 3d and O 2p orbitals, which promotes the inherent affinity of Ru@HEPO toward the LiO₂ intermediate, thereby reducing the reaction energy barrier of the oxygen electrode. As a result, the Ru@HEPO-based Li-O₂ batteries deliver remarkable electrochemical performances, such as high energy efficiency (87.3% at 100 mA g⁻¹), excellent rate capability (low overpotential of 0.52 V at 100 mA g⁻¹) and durable cyclability (345 cycles at 300 mA g⁻¹). This work opens up a promising avenue for the development of high entropy-based electrocatalysts for Li-O₂ batteries by precisely tailoring the electronic distributions at an atomic scale.