Competitive Solvation Chemistry Modulated Nonflammable Pseudo Ultralow Concentration Electrolyte Toward High‐Voltage Li Metal Batteries
Qifei Guo, Yongzhou Cai, Lu Chen, Zichen Lin, Biao Gao, Xuming Zhang, Xuequan Zhu, Yang Zheng, Zhuo Li, Kaifu Huo
Abstract
Abstract Lithium metal anodes are considered as optimal choice for high‐energy batteries; however, uncontrollable dendritic growth, low Coulombic efficiency, and safety concerns limit their practical applications. Herein, a concept of pseudo ultralow concentration electrolyte featuring high ion conductivity, high Li + transference number, nonflammability, and broad electrochemical window is proposed via incorporating a high ratio of fluoroether inert cosolvent into a phosphate‐based active solvent for high‐voltage lithium metal batteries. Intermolecular dipole–dipole interactions between the fluoroether and phosphate trigger a competitive solvation effect among the cosolvent, phosphate, and Li + , which can effectively regulate Li + solvation structure, thereby weakening the Li + ‐phosphate interaction and promoting anionic participation in the solvation sheath. Such enriched Li + ‐anion configuration facilitates the preferred decomposition of anions and the formation of highly conductive and mechanically robust solid electrolyte interphase, which induces dense and homogeneous lithium deposition and achieves high Li plating/stripping efficiency. Consequently, a Li||Cu cell with an as‐designed electrolyte obtains a high Coulombic efficiency of 99.1%. Additionally, the Li||NCM622 cell exhibits a high initial specific capacity of >170.8 mAh g −1 over 200 cycles with 99.4% capacity retention. This work presents a novel strategy for designing ultralow‐concentration electrolytes for high‐energy metal batteries.