Dual Protective Mechanism of AlPO₄Coating on High-Nickel Cathode Material for High Energy Density and Long Cycle Life Lithium-Ion Batteries

Cathode material with high nickel content is a promising candidate for the future generation of Li-ion batteries (LIBs). However, severe structural degradation during cycling limits its practical use, especially for electric vehicles. Herein, AlPO₄nanoparticles were synthesized and then coated onto the surface of a high-nickel layer-structured cathode via a dry coating method. The AlPO4 nanoparticles coating significantly improved the cycling stability from 69.2% to over 80% capacity retention after 140 cycles. Furthermore, the structure and chemical composition of the AlPO₄-coated cathode was investigated by XRD, SEM, XPS, and STEM. Compared with the non-coated cathode, we revealed a dual protective mechanism for enhanced cycling stability, where Al doping and Li₃PO₄coating play synergistic roles in protecting cathode material through long-term cycling. This work demonstrates a facile and environmentally friendly approach toward improving the performance of high-nickel LIB cathodes, which can be easily scaled up for industrial applications.