Atomic-level insights into the cycle performance of carboxylate electrolytes for high-voltage lithium metal batteries

DFT, AIMD, and classical MD simulations reveal that α-H activity and LUMO level is key factor in carboxylate reduction stability. • Propionate electrolytes exhibit narrower interfacial functional regions and enhanced protection. • Theoretical predictions are rigorously validated by experimental Li||NCM9055 full-cell cycling tests. Carboxylate solvents are essential for high-energy-density lithium metal batteries (LMBs) due to their low viscosity and superior low-temperature performance, yet conventional methyl acetate (MA) and ethyl acetate (EA) exhibit poor cycling stability caused by their inherent reduction instability. While a wide library of carboxylate derivatives exists with varying functional groups and chain lengths, their systematic structure-performance relationships remain elusive. In this work, we present an atomic-level investigation into 12 carboxylate solvents and their corresponding “single-salt–single-solvent” (4S) electrolytes using a combination of DFT, AIMD, and classical MD simulations. Our results reveal that the failure of MA- and EA-based systems stems from high α -H reactivity and unfavorable interfacial solvation structures, whereas propyl propionate (PP) and butyl propionate (BP) offer significantly enhanced reduction resistance and robust electrode-electrolyte interfaces. These computational predictions are in excellent agreement with experimental Li||NCM9055 full-cell cycling tests. This study elucidates the cyclic decay mechanism of short-chain esters and provides a theoretical foundation for the future design of high-performance carboxylate-based electrolytes for next-generation LMBs. Download: Download high-res image (277KB) Download: Download full-size image