LaF₃ & LaOF Nanophases Enhance High‐Voltage Electrochemical Performance of LiCoO₂

Comprehensive Summary LiCoO 2 (LCO) is a widely used cathode material for lithium‐ion batteries due to its high specific capacity and good rate capability. However, its practical application at high voltages (≥4.6 V) is severely limited by several critical issues, resulting in poor cycle stability and capacity fading. To address these challenges, LCO with LaF 3 & LaOF nanophases modification was synthesized via a solid‐state method, based on a synergetic strategy applying LaF 3 fast‐ion‐conducting coating to improve the interfacial ionic transport meanwhile constructing corrosion‐resistant LaOF to suppress degradation. Through the electrochemical performance tests at high voltages (≥4.65 V), the optimal LCO‐0.2LaF possesses superb high‐voltage electrochemical performance: the initial capacity equals 193.0 mA·h·g –1 with the retention of 91.1% after 100 cycles (1 C, 3.0–4.65 V); even at 1 C (3.0–4.70 V) the initial capacity is 207.7 mA·h·g –1 and the retention is 76.6% after 100 cycles. Structural characterizations, including in‐situ XRD, SEM, HRTEM, and XPS, etc ., reveal that the synergetic modification of LaF 3 and LaOF nanophases can effectively suppress O 2– peroxidation, Co dissolution and the drastic contraction and expansion of the lattice, thereby inhibiting the irreversible H3 → H1‐3 → O1 phase transition above 4.65 V.