Manipulating Electron Delocalization of Metal Sites via a High-Entropy Strategy for Accelerating Oxygen Electrode Reactions in Lithium-Oxygen Batteries.

Xu, Haoyang; Wang, Xinxiang; Tian, Guilei; Fan, Fengxia; Wen, Xiaojuan; Liu, Pengfei; Shu, Chaozhu · ACS Nano · 2024

basic_science · Level V

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Abstract

High-entropy perovskite oxides, in which the B-type metal site of perovskite oxides (ABO<sub>3</sub>) 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<sub>3</sub>) composed of Cr, Mn, Fe, Co, and Ni at the B-type metal site are prepared as oxygen electrocatalysts for Li-O<sub>2</sub> batteries. The presence of compressive strain in LaSr(5TM)O<sub>3</sub> effectively regulates the 3d orbit occupancy of the active Co site (Co<sup>2+</sup> → Co<sup>3+</sup>) and lifts the energy level of the Co d-band center, thus leading to enhanced adsorption toward the LiO<sub>2</sub> intermediate on Co sites. Furthermore, the high electron-drawing capability of Cr sites ensures sufficient electron exchange and further strengthens the adsorption of LiO<sub>2</sub>. As expected, the Li-O<sub>2</sub> battery with a LaSr(5TM)O<sub>3</sub> 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.