Tailoring Weakly Coordinating Electrolytes via Orbital‐Overlap‐Enhanced Dipole–dipole Interactions for Low‐Temperature Lithium‐Ion Batteries

Abstract

ABSTRACT Lithium‐ion batteries (LIBs) suffer rapid capacity fade at low temperatures. Weakly coordinating electrolytes via adding low‐polarity or non‐coordinating co‐solvents (such as fluorinated ethers) have shown promise in rapid desolvation, yet these electrolytes often exhibit low ionic conductivity at low temperature, limiting the application of high‐energy density LIBs. Here, we design a weakly coordinating electrolyte by incorporating the non‐coordinating co‐solvent (pentafluoroethyl)trimethylsilane (PFTMS) into the coordinating solvent diethyl carbonate (DEC) via orbital‐overlap‐enhanced dipole–dipole interactions. The slight Si─O orbital overlap drives strong dipole–dipole interactions between PFTMS and DEC. This interaction lowers the negative electrostatic potential at the carbonyl oxygen of DEC, thereby weakening Li + ‐DEC coordination. Thus, by leveraging enhanced dipole–dipole interactions, this strategy realizes a weak Li + ‐solvent coordination through a lower content of PFTMS (10 vol%) compared to traditional fluorinated solvents. Besides, the designed electrolyte delivers sufficient ionic conductivity of 1.56 mS cm −1 at −40°C. Accordingly, the graphite || LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) coin cell shows reversible capacity of 156.5mAh g −1 at −40°C. Notably, 4.7 Ah graphite || NCM811 pouch cell also demonstrates 219.8 Wh kg −1 at −20°C. This work advances the design of traditional weakly coordinating electrolytes via an orbital overlap strategy, which paves the way for application in extreme environments.