A Moderately Solvating Electrolytes for Lithium−ion Batteries: Co−intercalation−free and Wide−Temperature

Abstract

Ether-based electrolytes offer significant advantages for fast-charging and low-temperature lithium-ion batteries (LIBs) due to their low viscosity and melting points. However, conventional ether solvents suffer from co-intercalation into graphite (Gr) electrodes, leading to irreversible damage. Herein, a moderately solvating electrolyte (MSE) consisting of 1.0 M lithium bis(fluorosulfonyl)imide (LiFSI) in 2-methoxy-1,3-dioxolane (2MeODOL) for LIBs is designed to overcome the issues associated with LIBs. Computational analyses demonstrate that 2MeODOL strikes a balance between strong and weak solvation, enhancing Li⁺ transport and desolvation while suppressing solvent co-intercalation into Gr anodes. In practical Gr||LFP full cells, the MSE with 1 wt% VC achieved stable cycling performance, delivering a specific capacity of 120 mAh g⁻¹ and maintaining 93% capacity retention after 250 cycles at a charge/discharge current density of 1.0 C. Moreover, this electrolyte demonstrated excellent low-temperature operability at −40°C, surpassing traditional carbonate-based electrolytes. This study introduces a design concept for ether solvents that optimizes solvation power and expands the working temperature window, offering a promising route for high-energy-density LIBs.