Constructing Li₃PO₄ layer on LiNi_0.95Mn_0.05O₂ secondary particles to achieve synergistic optimization of electrochemical performance and storage stability

Balancing electrochemical durability and storage stability remains a major challenge for ultrahigh-Ni, Co-free cathodes. Herein, a uniform Li₃PO₄ coating is constructed on LiNi_0.95Mn_0.05O₂ (NM95) secondary particles to achieve synergistic optimization. The Li₃PO₄ layer act as a physical barrier, effectively isolating the cathode from direct contact with electrolyte and air. In addition, it significantly reduces the adsorption energies of H₂O and CO₂, thereby suppressing side reactions with environmental species. Meanwhile, strong P-O-Ni bonds are formed to stabilize highly reactive Ni species, while pronounced interfacial charge redistribution provides essential electron compensation to surface Li and O sites. These combined effects effectively preserve structural integrity and enhance interfacial stability. As a result, the Li₃PO₄-coated NM95 cathode delivers a reversible capacity of 175.6 mAh/g after 100 cycles, corresponding to 90.3% capacity retention, at 1C. Notably, it still maintains 174.9 mAh/g after 100 cycles even after 30 days of air exposure. This work demonstrates a simple and effective surface engineering strategy for simultaneously mitigating electrochemical degradation and storage-induced deterioration in ultrahigh-Ni cathodes.