Weakly‐Solvated and Co‐Intercalation‐Free Ether‐Based Electrolytes Enhance the Low‐ Temperature and Fast‐Charging Performance of LiFePO ₄ ||Graphite Batteries

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.