A weakly-solvated ether-based electrolyte for fast-charging graphite anode

Weakly-solvated electrolytes (WSEs) utilizing solvents with weak coordination ability offer advantages for low-potential graphite anode owing to their facile desolvation process and anions-derived inorganic-rich solid electrolyte interphase (SEI) film. However, these electrolytes face challenges in achieving a balance between the weak solvation affinity and high ionic conductivity, as well as between rigid inorganic-rich SEI and flexible SEI for long-term stability. Herein, we introduce 1,3-dioxolane (DOL) and lithium bis(trifluoromethanesulfonyl)-imide (LiTFSI) as functional additives into a WSE based on nonpolar cyclic ether (1,4-dioxane). The well-formulated WSE not only preserves the weakly solvated features and anion-dominated solvation sheath, but also utilizes DOL to contribute organic species for stabilizing the SEI layer. Benefitting from these merits, the optimized electrolyte enables graphite anode with excellent fast-charging performance (210 mAh/g at 5C) and outstanding cycling stability (600 cycles with a capacity retention of 82.0% at room temperature and 400 cycles with a capacity retention of 80.4% at high temperature). Furthermore, the fabricated LiNi0.8Co0.1Mn0.1O2||graphite full cells demonstrate stable operation for 140 cycles with high capacity retention of 80.3%. This work highlights the potential of tailoring solvation sheath and interphase properties in WSEs for advanced electrolyte design in graphite-based lithium-ion batteries.