Tailoring Electrolyte Dehydrogenation with Trace Additives: Stabilizing the LiCoO<sub>2</sub> Cathode beyond 4.6 V
Yawen Yan, Suting Weng, Ang Fu, Haitang Zhang, Jianken Chen, Qizheng Zheng, Baodan Zhang, Shiyuan Zhou, Hao Yan, Chuanwei Wang, Yonglin Tang, Haiyan Luo, Bing‐Wei Mao, Jianming Zheng, Xuefeng Wang, Yu Qiao, Yong Yang, Shi‐Gang Sun
Abstract
Extending the charge cutoff voltage of cathode (e.g., LiCoO2) is a promising way to increase the energy density of Li-ion batteries, but critical challenges lie in the threats triggered by structural distortion and an unstable electrode/electrolyte interface. The general approach to enhance the stability of the cathode/electrolyte interface (CEI) consists of replacing the decomposition or sacrificing sources of carbonate solvents (e.g., EC) with concentrated or fluorinated electrolyte strategies. Herein, without following typical replacement strategies, we introduce a trace electrolyte additive and refine the dehydrogenation process of the original carbonate solvents, resulting in an enhanced CEI and long-term cycling stability of LiCoO2 up to 4.65 V. We demonstrate that cathode structure distortion, LiPF6 hydrolysis, and Co dissolution and shuttling have been simultaneously restrained. With the achievement of a long-life 250 and 270 Wh/kg pouch cells (assembled with a commercial graphite and SiO anodes), the refinement of the “old-school” electrolyte additive strategy opens up avenues toward the design of practical high-voltage full-cell systems.