Overcoming low-temperature challenges in LIBs: the role of anion-rich solvation sheath in strong solvents

Abstract

Lithium-ion batteries (LIBs) face significant limitations in low-temperature environments, with the slow interfacial de-solvation process and the hindered Li⁺ transport through the interphase layer emerging as key obstacles beyond the issue of ionic conductivity. This investigation unveils a novel formulation that constructs an anion-rich solvation sheath within strong solvents, effectively addressing all three of these challenges to bolster low-temperature performance. The developed electrolyte, characterized by an enhanced concentration of contact ion pairs (CIPs) and aggregates (AGGs), facilitates the formation of an inorganic-rich interphase layer on the anode and cathode particles. This promotes de-solvation at low temperatures and stabilizes the electrode–electrolyte interphase. Full cells composed of LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) and graphite, when equipped with this electrolyte, showcase remarkable cycle stability and capacity retention, with 93.3% retention after 500 cycles at room temperature (RT) and 95.5% after 120 cycles at −20 °C. This study validates the utility of the anion-rich solvation sheath in strong solvents as a strategy for the development of low-temperature electrolytes.