Layered LiNi_0.6Co_0.2Mn_0.2O₂ (NMC) is a promising cathode material for lithium-ion batteries, but structural instability and rapid capacity decay at high voltages and elevated temperatures preclude its large-scale commercialization. Lattice doping and surface coating can address these problems, but the different mechanisms between them are still unclear. Herein, two kinds of cathode materials (Zr-doped NMC and ZrO₂-coated NMC) are synthesized and the effects of doping and coating on the structural stability and electrochemical performance of NMC are systematically investigated. Zr-doped NMC exhibits superior electrochemical performance with 98% capacity retention after 50 cycles between 3.0 and 4.5 V at 55 °C. In contrast, pristine and ZrO₂-coated NMC suffer continual capacity decay during cycling. Ex situ analyses reveal that the performance improvement originates from the structure stabilizing effects of Zr doping and the robust interfacial film on the cathode surface during cycling. The results suggest that lattice doping is a key factor in obtaining excellent cycling performance at high temperatures. This study provides further insight into the different effects of Zr doping/coating and can be extended to investigate other cathode materials.

层状LiNi _0.6 Co _0.2 Mn _0.2 O ₂（NMC）是一种有前途的锂离子电池正极材料，但是在高电压和高温下结构不稳定性和快速的容量衰减使其无法大规模商业化。晶格掺杂和表面涂层可以解决这些问题，但是它们之间的不同机制仍不清楚。在这里，两种阴极材料（掺Zr的NMC和ZrO ₂合成了NMC涂层），系统研究了掺杂和涂层对NMC结构稳定性和电化学性能的影响。掺杂Zr的NMC表现出卓越的电化学性能，在55°C下在3.0至4.5 V之间的50个循环后，具有98％的容量保持率。相反，原始的和ZrO ₂涂层的NMC在循环过程中会承受连续的容量衰减。异地分析表明，性能提高源自循环过程中Zr掺杂的结构稳定作用和阴极表面上的坚固界面膜。结果表明，晶格掺杂是在高温下获得优异循环性能的关键因素。这项研究提供了对Zr掺杂/涂层的不同影响的进一步见解，并且可以扩展到研究其他阴极材料。