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

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.