富锂层状氧化物作为锂离子电池正极材料具有高比容量优势. 采用草酸盐共沉淀法制备Li(Li_0.22Ni_0.17Mn_0.61)O₂，并用YF₃包覆电极. 采用X-射线衍射（XRD）、扫描电子显微镜（SEM）和X-射线能谱分析（EDS）表征材料结构、观察材料形貌. 研究结果表明，材料颗粒尺寸在100 ~ 200 nm范围，YF3包覆不会改变材料结构和形貌. 电化学恒流充放电测试表明，YF₃包覆Li(Li_0.22Ni_0.17Mn_0.61)O₂电极的比容量，尤其倍率比容量，明显提高. 60 mA.g^-1电流密度包覆电极材料30周循环后其比容量保持在220 mAh.g^-1以上，1500 mA.g^-1电流密度其比容量仍可达150 mAh.g^-1. 电化学阻抗谱（EIS）测试结果表明，YF₃包覆电极电荷转移电阻和扩散阻抗均明显降低，电化学性能改善.

The Li(Li_0.22Ni_0.17Mn_0.61)O₂ was prepared with oxalic co-precipitation and coated with an YF₃ layer by a chemical deposition method. The as-prepared and YF₃-coated Li-rich materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results demonstrate that the as-prepared and YF₃-coated Li(Li_0.22Ni_0.17Mn_0.61)O₂ materials have a typical layered structure and are composed of sphere-like particles with a diameter of 100~200 nm. Galvanostatic charge-discharge tests show that the discharge capacity of the YF₃-coated Li(Li_0.22Ni_0.17Mn_0.61)O₂ is obviously improved. At the low current density of 60 mA.g^-1, the discharge capacity reaches 240 mAh.g^-1, and remains 220 mAh.g^-1 after 30 cycles. At the high current density of 1500 mA.g^-1, the discharge capacity still keeps 150 mAh.g^-1, showing an excellent high-rate capability. Electrochemical impedance spectra (EIS) reveal that the YF₃-coated Li(Li_0.22Ni_0.17Mn_0.61)O₂ shows lower charge-transfer resistance and diffusion impedance as compared with the as-prepared Li(Li_0.22Ni_0.17Mn_0.61)O₂.