Toward Ultralow Temperature Lithium Metal Batteries: Advancing the Feasibility of 1,3-Dioxolane Based Localized High-Concentration Electrolytes via Lithium Nitrate

Abstract

Lithium metal batteries (LMBs) suffer severe capacity deterioration due to sluggish ionic transport kinetics at extremely low temperatures, which limits their practical operation. Selecting solvents with low desolvation energy, and promoting interfacial Li⁺ transport in solid electrolyte interphase (SEI) are regarded as effective methods to improve electrochemical performances. Herein, 1,3-dioxolane (DOL) with weak solvating power is adopted for designing a DOL-based localized high concentration electrolyte (DLHCE) with LiNO₃ as a multifunctional additive. The strong coordination between NO₃⁻ and DOL molecules not only inhibits the polymerization of DOL at high lithium bis(fluorosulfonyl)imide (LiFSI) concentration, but also reduces the solvent-diluent miscibility and extends the salt-solvent solubility. As a result, an anion-dominated solvation structure is obtained that derives an inorganic-rich SEI composed of LiF and Li₃N, guiding the uniform deposition of Li at low temperature. Remarkably, the Li||LiFePO₄ cells retain 53.6% of room temperature capacity at −40 °C, and also present potential application of Li||NCM811 cells under cryogenic environments.