In-Situ Formation of a LiF-Rich Interphase for Graphite Anode Operated at Low Temperatures

Abstract

Inorganic LiF is generally a desirable component in solid electrolyte interface (SEI) for graphite anode due to its electronic insulation, low Li⁺ diffusion barrier, high modulus and good chemical stability. Herein, fluorinated carbon (CF_x) was incorporated into graphite material, which exhibited a high discharge potential prior to electrolyte decomposition and in-situ formed a crystalline LiF-based SEI with improved Li⁺ diffusion rate. The optimized graphite anode therefore demonstrated a fast-charging capability with 124 mAh g⁻¹ at high rate of 8 C and a remarkable capacity retention of 83.8 % at the low temperature of −30 °C compared to that at 25 °C. Furthermore, the optimized graphite|LiFePO₄ full cell exhibited a significantly high discharge capacity of 109 mAh g⁻¹ at −30 °C, corresponding to a notable 77.3 % room-temperature capacity retention. These findings highlight a facile strategy to attain a LiF-rich SEI for high-performance lithium-ion batteries.