Suppressing Irreversible Interfacial Spatial Electron Transfer for High-Temperature 4.6 V LiCoO₂

The practical deployment of high-voltage (≥4.5 V) LiCoO₂ (LCO) cathodes under elevated temperatures is essential for meeting the growing energy-storage demands across diverse applications. However, it is severely hindered by interfacial parasitic reactions arising from irreversible electron transfer between electrolyte solvents and the cathode. Herein, we demonstrate the regulation of the spatial distance and orientation of phosphate solvent molecules within the electric double layer at the LCO interface, thereby fundamentally suppressing irreversible interfacial spatial electron transfer (ISET) under combined high-voltage and high-temperature conditions. The fluorinated bidentate phosphate ester (TEFP) creates a compact solvation sheath that counteracts the interfacial-electric-field-driven enrichment of phosphate solvents, increases the solvent-cathode distance, and maintains a P═O orientation away from the cathode, thereby suppressing ISET from the P═O bond to the delithiated LCO. This simultaneously promotes the formation of a well-controlled, uniform, and stable cathode-electrolyte interphase. Consequently, Li||LCO cells with TEFP electrolyte deliver superior cycling stability at 4.6 V and elevated temperatures, with 80% capacity retention after 760 cycles at 60°C and 75.5% after 300 cycles at 80°C, while Ah-level pouch cells further validate the practical viability of the electrolyte. This work provides guidance for the design of cathode interfaces under high-voltage and high-temperature conditions.