Controllable Regulation of the Oxygen Redox Process in Lithium–Oxygen Batteries by High-Configuration-Entropy Spinel with an Asymmetric Octahedral Structure
Guilei Tian, Haoyang Xu, Xinxiang Wang, Xiaojuan Wen, Pengfei Liu, Sheng Liu, Ting Zeng, Fengxia Fan, Shuhan Wang, Chuan Wang, Chenrui Zeng, Chaozhu Shu
Abstract
Designing bifunctional electrocatalysts to boost oxygen redox reactions is critical for high-performance lithium–oxygen batteries (LOBs). In this work, high-entropy spinel (Co 0.2 Mn 0.2 Ni 0.2 Fe 0.2 Cr 0.2 ) 3 O 4 (HEOS) is fabricated by modulating the internal configuration entropy of spinel and studied as the oxygen electrode catalyst in LOBs. Under the high-entropy atomic environment, the Co–O octahedron in spinel undergoes asymmetric deformation, and the reconfiguration of the electron structure around the Co sites leads to the upward shift of the d-orbital centers of the Co sites toward the Fermi level, which is conducive to the strong adsorption of redox intermediate LiO 2 on the surface of the HEOS, ultimately forming a layer of a highly dispersed Li 2 O 2 thin film. Thin-film Li 2 O 2 is beneficial for ion diffusion and electron transfer at the electrode–electrolyte interface, which makes the product easy to decompose during the charge process, ultimately accelerating the kinetics of oxygen redox reactions in LOBs. Based on the above advantages, HEOS-based LOBs deliver high discharge/charge capacity (12.61/11.72 mAh cm –2 ) and excellent cyclability (424 cycles). This work broadens the way for the design of cathode catalysts to improve oxygen redox kinetics in LOBs.