Interfacial Engineering With a Multifunctional LaPO4/LaF3 Coating Enables Durable 4.65 V LiCoO2 Cathodes With High-Rate Capability.

Abstract

High-power fast-charging lithium-ion batteries (LIBs) are indispensable energy sources for electric vehicles and consumer electronics. LiCoO2 (LCO) offers remarkable energy density and high voltage but suffers from structural degradation and irreversible O3/H1-3 phase transition at high voltage (e.g., 4.65 V), thus limiting its practical use. This study introduces a novel multifunctional LaPO4/LaF3 coating to tackle the structural and interfacial engineering plaguing LCO at 4.65 V. The LaPO4/LaF3 coating effectively reduces interfacial side reactions on LCO by inhibiting structural degradation and intergranular cracks, enables a more reversible O3/H1-3 phase transition, and enhances rapid Li+ transport at the electrode surface. The interfacial engineering of the LaPO4/LaF3 coating also stabilizes the lattice oxygen of LCO by suppressing side reactions and Co dissolution. Specifically, the modified LCO exhibits a capacity retention rate of 79.3% after 1500 cycles when charged to 4.65 V at 5C, highlighting its exceptional electrochemical performance. Further, the assembled pouch cell shows a capacity retention of 89.9% after 200 cycles at 4.6 V with 1C. In particular, these findings offer critical insights into stabilizing LCO at elevated operating voltages, thereby opening new pathways for the development of high-power fast-charging LIBs.