Manipulating Electron Delocalization of Metal Sites via a High-Entropy Strategy for Accelerating Oxygen Electrode Reactions in Lithium–Oxygen Batteries
Haoyang Xu, Xinxiang Wang, Guilei Tian, Fengxia Fan, Xiaojuan Wen, Pengfei Liu, Chaozhu Shu
Abstract
High-entropy perovskite oxides, in which the B-type metal site of perovskite oxides (ABO 3 ) is occupied by over five kinds of transition metal ions, show promising applications in energy storage and conversion fields. Herein, high-entropy perovskite oxides (LaSr(5TM)O 3 ) composed of Cr, Mn, Fe, Co, and Ni at the B-type metal site are prepared as oxygen electrocatalysts for Li–O 2 batteries. The presence of compressive strain in LaSr(5TM)O 3 effectively regulates the 3d orbit occupancy of the active Co site (Co 2+ → Co 3+ ) and lifts the energy level of the Co d-band center, thus leading to enhanced adsorption toward the LiO 2 intermediate on Co sites. Furthermore, the high electron-drawing capability of Cr sites ensures sufficient electron exchange and further strengthens the adsorption of LiO 2 . As expected, the Li–O 2 battery with a LaSr(5TM)O 3 electrode delivers a low overpotential (0.79 V) and superior cyclability (226 cycles). This study provides a meaningful strain strategy to improve the electrocatalytic activity of multicomponent oxides via fabricating high-entropy materials.