Weakly‐Solvated and Co‐Intercalation‐Free Ether‐Based Electrolytes Enhance the Low‐ Temperature and Fast‐Charging Performance of LiFePO <sub>4</sub> ||Graphite Batteries
Ziwei Wang, Xuewei Gu, Jiacheng Zhu, Cong Zhong, Shiwei Xu, Suting Weng, Bowen Liu, Zhaoxiang Wang, Yejing Li, Tao Cheng, Xuefeng Wang
Abstract
Abstract Lithium‐ion batteries (LIBs) employing lithium iron phosphate (LiFePO 4 , LFP) cathodes and graphite (Gr) anodes are extensively utilized for energy storage applications because of their exceptional cycle life and inherent safety characteristics. However, sluggish desolvation kinetics and interfacial Li⁺ transport hinder their fast‐charging capability and low‐temperature performance, limiting broader applications. In this work, we propose a weakly solvating ether (WSE) electrolyte based on 2‐methyl‐tetrahydrofuran (2MT) as the main solvent. This electrolyte results in considerable steric hindrance, effectively preventing co‐intercalation with Gr, while also providing a weak solvation capability for Li⁺ ions and facilitating rapid interfacial Li⁺ transport. WSE, formulated with 2MT and fluoroethylene carbonate (FEC) as a co‐solvent, combines fast desolvation kinetics with an extremely low freezing point of −117.67 °C. This electrolyte induces the formation of a LiF‐, Li 3 N‐, Li 2 CO 3 ‐, and Li 2 O‐rich solid electrolyte interphase (SEI) on the Gr anode, thereby enhancing low‐temperature interfacial transport. Consequently, the Gr||Li half‐cell and the LFP||Gr full cell with this WSE demonstrates excellent rate performance, stable cycling stability, and a high specific capacity at −30 °C while also delivering reliable power even at −60 °C. These results underscore the electrolyte's efficient desolvation process, stable SEI layer, and excellent compatibility with graphite, rendering it ideal for extreme‐temperature applications.