Cation Vacancy Modulated Interfacial Electronic Interactions for Enhanced Electrocatalysis in Lithium–Oxygen Batteries

Abstract

AbstractLi–O2 batteries deliver ultrahigh theoretical specific energy while suffering from low energy efficiency and poor cyclability due to sluggish kinetics of oxygen electrode reactions. Herein, a strategy of engineering interfacial electron structure of MXene‐based composites is presented to boost oxygen electrode reactions for advancing Li–O2 batteries with the cation vacancy‐rich CoSe@MXene (VCo‐CoSe2@MXene) as the case study. The formation of interfacial Co─C bond between VCo‐CoSe2 and Ti3C2 MXene and its enhanced covalency after introducing Co vacancy leads to promoted electron transfer from Ti3C2 MXene to CoSe2 and optimized electronic structure of interfacial Co sites, especially the second Co sites neighboring Co vacancy, which serve as the active centers for oxygen redox reactions. On this basis, VCo‐CoSe2@MXene‐based Li─O2 batteries exhibit low overpotential (0.35 V) and excellent cycling stability (250 cycles at 500 mA g−1). This work proposes an effective strategy to develop MXene‐based electrocatalysts for Li–O2 batteries by tailoring interfacial electron structure.