China Nonferrous Metallurgy

Ultra-high nickel layered material LiNi_0.92Co_0.04Mn_0.04O₂ (Abbr. NCM92) has become one of the important cathode sources for lithium-ion batteries due to its high energy density and price advantages. However, a key challenge for commercial applications is rapid capacity fading and severe structural degradation, especially at high cut-off voltages, resulting from interface instability and irreversible phase transitions. In this study, a ZrO₂/Li₂ZrO₃ double coating modified ultra-high nickel single crystal cathode material was designed, and the surface of the material was uniformly doped with Zr element, which significantly enhanced the high cut-off voltages performance and structural stability of the cathode electrode through the synergic strategy of double coating. The results show that the ZrO₂/Li₂ZrO₃ double coating can effectively alleviate the irreversibility of H2-H3 phase transition of the ultra-high nickel cathode material, improve the mechanical stability and interface stability. At the same time, the TM layer and Li site of the surface Zr doping into the crystal structure inhibit the Li/Ni mixing and widen the lattice spacing. As expected, ZrO₂/Li₂ZrO₃ double-coated with Zr-doped modified materials (NCM92-Zr) demonstrated excellent electrochemical properties at 0.5 C (200mA·g^-1) current densities, after 150 cycles in the voltage range of 2.75~4.4V, the discharge specific capacity of 155.2mAh·g^-1 remains, and the capacity retention is 75.5%. The study provides new insights into the complex mechanisms and improved structural stability of ultra-high nickel cathode at high cut-off voltages.