Electric Field-Insensitive Solvation Chemistry Stabilizes High-Voltage Lithium Metal Batteries

Ether based electrolytes are promising for the realization of lithium (Li) metal batteries (LMBs). However, the oxidation chemistry of these electrolytes stemming from the disruption to solvent coordination by interfacial electric-field remains unresolved and challenging. Herein, we demonstrated that reinforcing the interactions between solvent and diluent to decouple solvation dynamics from interfacial electric fields could maintain Li⁺-solvent coordination integrity and drastically diminish uncoordinated solvents, thereby increasing electrolyte anodic stability. To realize this concept, we identify a class of solvophilic diluents (SPDs, whose interaction energies with solvent>3.3 kcal mol^-1) to strongly anchor diethylene glycol dimethyl ether (DEGDME) solvent at electrified interfaces via mutually reinforcing H_(DEGDME)···F/O_(SPD) and H_(SPD)···O_(DEGDME) interactions and effectively decrease dipole moment of DEGDME (< 2.47 D), creating an electric field-insensitive solvation environment wherein the O─H/C─H bond polarization of DEGDME is dramatically impeded. Remarkably, our designed SPD-assisted electrolyte mediated by electric field-insensitive methyl nonafluorobutyl ether exhibits outstanding anodic stability, endowing 4.7 V-class 30 µm Li||2.1 mAh cm^-2 LiNi_0.8Co_0.1Mn_0.1O₂ cell with 80% capacity retention after 168 cycles-an improvement over the 90 cycles achieved with a Li friendly electrolyte. This work establishes a mechanistic framework for manipulating interfacial solvation dynamics to unlock high-voltage LMBs.