中文摘要：

利用溶胶一凝胶法在LiNi1／3Co1／3Mn1／3O2颗粒表面包覆一层纳米级厚度的Al2O3，提高了其高截止电压下的循环性能和倍率。陛能。采用X射线衍射（XRD）、扫描电子显微镜（SEM）和透射电子显微镜法（TEM）对所制备材料进行结构和微观形貌表征，通过充放电测试对材料的电化学性能进行分析。结果表明：Al2O3包覆层对材料的结构和微观形貌没有影响；Al2O3的最佳包覆量为2．O％（质量分数），此时包覆层的厚度为20∽30nm。在2．8∽4．5V电压范围内。未包覆的LiNi1/3Co1/3mMn1/3O2在0．2C时的首次放电比容量为175mAh／g，50次循环后容量保持率只有91．8％；经Al2O3包覆的LiNi1／3Co1／3Mn1／3O2在0．2C下，首次放电比容量达到181mAh／g，经50次循环后容量保持率仍可达到97．4％。且在5C放电条件下，其放电比容量可达152mAh／g，显示了该包覆材料在高能量密度长寿命锂离子电池中将具有很大的应用潜力。

英文摘要：

A layer of nano Al2O3 was coated on the surface of LiNi1/3Co1/3Mn1/3O2 particles by sol-gel method, so the cycle performance and rate capability of LiNi1/3Co1/3Mn1/3O2 at a high cut-off voltage are enhanced. The structure and morphology of the materials were characterized by XRD, SEM and TEM. The electrochemical performances of the high voltage cathodes were galvanostatically evaluated. The results show that the structure of the materials does not change after coating. The optimized coating content of Al2O3 is 2.0%, corresponding to the layer of 20-30 nm. The electrochemical performances of LiNi1/3Co1/3Mn1/3O2 cathode materials are obviously improved by the AI203 layer. At the range of 2.8-4.5 V, the first discharge specific capacity of uncoated LiNi1/3Co1/3Mn1/3O2 materials is 175 mAh/g at 0.2 C, and the capacity retention after 50 cycles is 91.8%. At the same charge-discharge conditions, the first specific discharge capacity of coated LiNi1/3Co1/3Mn1/3O2 materials increases to 181 mAh/g, and the capacity retention after 50 cycles still reaches 97.4%. Even at 5 C, the discharge specific capacity of coated LiNi1/3Co1/3Mn1/3O2 materials is 152 mAh/g. The coated LiNi1/3Co1/3Mn1/3O2 materials exhibit huge potential in the lithium ion batteries with high energy density and long cycle life.