Constructing Li3PO4 layer on LiNi0.95Mn0.05O2 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 LiNi0.95Mn0.05O2 (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.