Heavy Fluorination via Ion Exchange Achieves High‐Performance Li–Mn–O–F Layered Cathode for Li‐Ion Batteries
Junliang Lu, Bo Cao, Bingwen Hu, Yuxin Liao, Rui Qi, Jiajie Liu, Changjian Zuo, Shenyang Xu, Zhibo Li, Cong Chen, Ming‐Jian Zhang, Feng Pan
Abstract
Abstract Lithium‐excess manganese layered oxide Li 2 MnO 3 , attracts much attention as a cathode in Li‐ion batteries, due to the low cost and the ultrahigh theoretical capacity (≈460 mA h g −1 ). However, it delivers a low reversible practical capacity (<200 mA h g −1 ) due to the irreversible oxygen redox at high potentials (>4.5 V). Herein, heavy fluorination (9.5%) is successfully implemented in the layered anionic framework of a Li–Mn–O–F (LMOF) cathode through a unique ion‐exchange route. F substitution with O stabilizes the layered anionic framework, completely inhibits the O 2 evolution during the first cycle, and greatly enhances the reversibility of oxygen redox, delivering an ultrahigh reversible capacity of 389 mA h g −1 , which is 85% of the theoretical capacity of Li 2 MnO 3 . Moreover, it also induces a thin spinel shell coherently forming on the particle surface, which greatly improves the surface structure stability, making LMOF exhibit a superior cycling stability (a capacity retention of 91.8% after 120 cycles at 50 mA g −1 ) and excellent rate capability. These findings stress the importance of stabilizing the anionic framework in developing high‐performance low‐cost cathodes for next‐generation Li‐ion batteries.