Ni-rich layered oxide is a promising cathode material for future advanced lithium-ion batteries (LIBs). However, the nickel-rich layered cathode material exhibits insufficient high-voltage cycling stability ascribing to the phase transformation, surface side reactions, and lattice oxygen evolution. This work developed an effective inorganic coating strategy to construct LiNiO₂/Na_1-xNi_1-yPO₄ surface hybrid coating layer and Na bulk doping simultaneously by a simple wet-chemical method, improving the high-voltage performance of LiNi_0.8Co_0.1Mn_0.1O₂ (NCM) effectively. It is found that the surface oxygen vacancy and surface residual lithium on NCM reacts with NaNiPO₄ precursors at 500 °C to form LiNiO₂ inner layer in addition to the Na_1-xNi_1-yPO₄ outer layer, which is structurally coherent to the layered lattice of NCM. In the constructed hybrid layer, layered phase LiNiO₂ firmly fixes on the NCM surface. At the same time, highly chemical stable Na_1-xNi_1-yPO₄ with lattice tunnels can enable lithium-ion transport and act as a protecting layer to inhibit surface side reactions. In addition, Na bulk doping could enlarge lithium-ion diffusion channels and stabilize lattice structure. All these advantages contribute to improving the electrochemical performance of NCM. The results show that the surface treatment NCM cathode exhibit excellent cycling stability with a higher capacity retention of 88 % after 200 cycles under 25 °C and 86 % after 100 cycles under 55 °C, both at 1C. This method provides a feasible strategy to promote the high-voltage cycling performance of electrode material, thus improving the service life, energy density, and safety performance of Li-ion batteries.

富镍层状氧化物是未来先进锂离子电池（LIB）的一种很有前途的正极材料。然而，由于相变、表面副反应和晶格氧析出，富镍层状正极材料的高压循环稳定性不足。本工作开发了一种有效的无机涂层策略，通过简单的湿化学方法同时构建 LiNiO ₂ /Na _1-x Ni _1-y PO _{4表面杂化涂层和 Na 本体掺杂，提高了 LiNi 0.8} Co的高压性能_0.1锰_0.1 O ₂(NCM) 有效。发现NCM上的表面氧空位和表面残留锂在500℃下与NaNiPO ₄前驱体反应形成除Na _1-x Ni _1-y PO ₄外层外的LiNiO ₂内层，结构上是共格的。到 NCM 的层状晶格。在构建的杂化层中，层状相LiNiO ₂牢固地固定在NCM表面。同时，化学稳定性高的 Na _1-x Ni _1-y PO ₄具有晶格隧道可以使锂离子传输并充当保护层以抑制表面副反应。此外，Na体掺杂可以扩大锂离子扩散通道并稳定晶格结构。所有这些优点都有助于提高 NCM 的电化学性能。结果表明，表面处理的NCM正极表现出优异的循环稳定性，在25°C下200次循环后容量保持率为88%，在55℃下100次循环后容量保持率为86%，均为1C。该方法为提高电极材料的高压循环性能提供了可行的策略，从而提高了锂离子电池的使用寿命、能量密度和安全性能。