Ethyl difluoroacetate additive engineering for fast-charging and durable graphite anodes in lithium-ion batteries

The practical application of fast-charging lithium-ion batteries is hindered by interfacial instability at graphite anodes, primarily due to uncontrolled electrolyte decomposition and the formation of resistive solid electrolyte interphase (SEI) layers. Herein, we report ethyl difluoroacetate (EDFA) as a fluorinated additive for conventional LiPF₆/EC-EMC electrolytes to address these challenges. Electrochemical measurements demonstrate that EDFA undergoes preferential reduction to form a stable, fluorine-rich SEI, which enhances interfacial stability and facilitates Li⁺ transport. As a result, graphite/Li half-cells with EDFA exhibit significantly improved performance, with capacity retention increasing from 81.8 % to 93.4 % after 100 cycles and 3C-rate capacity rising from 49.1 to 99.5 mAh·g⁻¹. SEM, TEM, and XPS analyses confirm the formation of a uniform, compact and fluorine-rich SEI that mitigates parasitic reactions and reduces impedance. This work provides a viable strategy to enhance fast-charging performance in commercial battery systems through additive engineering.