Carbophilicity-Enabled No-Diluent High-Concentration Electrolytes for Stable Fast Charging of Graphite Anode

High-concentration electrolytes (HCEs) are promising for fast-charging graphite anodes because anion-rich solvation promotes LiF-enriched interphases and improves Li plating reversibility. However, their high viscosity often limits ionic conductivity and pore infiltration. Localized HCEs mitigate these limitations using fluorinated diluents, but at increased cost and reduced sustainability. Here, a diluent-free methyl acetate (MA)-based HCE is developed to address the viscosity‒transport trade-off through a carbophilicity-guided design. The MA-HCE delivers the most favorable conductivity‒viscosity balance among the investigated 5 M LiFSI electrolytes. Beyond bulk transport, MA exhibits high carbophilicity, defined as the strong interfacial affinity of electrolyte species toward carbon surfaces. Multiphysics simulations, DFT adsorption analysis, and operando Raman show that both free MA molecules and MA-involved solvation clusters enhance graphite wetting and accelerate pore infiltration, thereby improving near-electrode ion supply under high current. As a result, the MA-HCE enables deeper Li intercalation with a reduced plating fraction (24.7%) and highly reversible Li deposition (99.91%). In 1.0 Ah pouch cells, MA-HCE sustains 1200 cycles at 4 C with 80% capacity retention. This work demonstrates that carbophilicity can serve as an effective design principle to overcome the viscosity‒transport trade-off in HCEs and enable stable fast charging of graphite.