Steric‐Electronic Engineering of Ester Carbonyls Enables Thermodynamic‐Kinetic Regulation of Electron Transfer for High‐Voltage and High‐Rate Lithium Metal Batteries

ABSTRACT Ester‐based electrolytes, widely used in lithium‐ion batteries (LIBs), suffer from the intrinsically unstable carbonyl groups that trigger uncontrollable reductive decomposition, along with the narrow operating temperature window, limiting their application in high‐energy lithium metal batteries (LMBs). In this study, we establish a molecular‐level electron transfer regulation strategy toward ester carbonyls that simultaneously suppresses electron transfer thermodynamically and kinetically, while tailoring the solvation structure, thereby converting uncontrolled solvent decomposition into well‐defined interphase chemistry. This strategy ultimately yields a lightweight, wide‐temperature, and stable ethyl pivalate‐based electrolyte. The electrolyte supports stable operation from −40°C to 50°C and robust cycling in Li||NCM 811 cells at 4.6 V and 10 C. Commercially relevant Li||NCM 811 full cells further demonstrate exceptional durability at 4.6 V, with negligible capacity decay over 300 cycles. A 432 Wh kg −1 pouch cell (2.5 Ah) with a low negative/positive ratio of 0.94 and lean electrolyte (1.17 g Ah −1 ), stable cycling under high‐voltage (4.6 V) conditions. We believe the findings may extend to other ester‐based electrolytes and inform sodium/potassium/calcium/magnesium battery systems.