Optimize Lithium Deposition at Low Temperatures by a Localized High Concentration Carboxylic Ester-Based Electrolyte

Lithium (Li) metal with an ideally host-less nature and theoretical capacity is considered the most promising anode for batteries at low temperatures. However, due to the low conductivity, high viscosity, and strong solvation energy of traditional carbonate electrolytes, the operation of Li-metal batteries remains a challenge at low temperatures. In this work, a local high-concentration electrolyte (LHCE) based on methyl acetate (MA) is developed to regulate the solvation structure and solid electrolyte interphase (SEI) of Li-metal batteries at subzero temperatures. Benefiting from the anion-dominated internal solvation sheath of Li+ ions and LiF-enriched SEI, the LHCE exhibits good compatibility with the Li metal anode. The symmetric Li||Li battery can cycle stably for more than 1000 h at a current density of 0.5 mA cm–2. A capacity retention of 84.3% over 400 cycles at 0.5 C (1 C = 170 mA g–1) is achieved when paired with a LiFePO4 (LFP) cathode. At −15 °C, the Li||LFP battery can still deliver a high reversible capacity of 80% over 200 cycles at 0.2 C. This work provides an insightful reference for the development of electrolyte systems under low-temperature applications.