Localized High-Concentration Electrolyte (LHCE) for Fast Charging Lithium-Ion Batteries

The solid electrolyte interphase (SEI) significantly influences the electrochemical performance of lithium-ion batteries. Traditional electrolytes, particularly ether electrolytes, make it challenging to form a stable SEI film, and the corresponding lithium-ion batteries frequently exhibit poor electrochemical performance. In this paper, we develop a stable SEI film to improve fast charging and cycle performance using a localized high concentration electrolyte (LHCE). A unique solvation sheath formed by the coordination of Li⁺, anion, and solvent in the LHCE caused the anion to migrate quickly to the surface of the graphite anode and decompose to form a LiF-rich SEI. A LHCE enabled the Li||C battery to maintain a capacity of 124 mAh g⁻¹ at a rate of 5 C, and the capacity remained at 289 mAh g⁻¹ after 150 cycles at a rate of 0.1 C, with a capacity retention rate of 73% and an average coulomb efficiency of about 99.8%, thus demonstrating excellent long-cycle performance. The LFP||Li battery capacity at a 5 C rate can also be maintained at 102 mAh g⁻¹.