(中南大学 冶金科学与工程学院，长沙 410083)
摘 要: 采用草酸盐前驱体合成Ti4+、Mg2+掺杂正极材料Li(Nil/3Col/3−xMnl/3)MxO2(M=Ti, Mg)。利用XRD和SEM对其结构和形貌进行表征，并采用循环伏安、交流阻抗、恒流/恒压充放电测试其电化学性能。结果表明：Ti4+、Mg2+掺杂后晶胞体积增大，大倍率充放电时LiNil/3Col/3Mnl/3O2的电化学反应阻抗Rct降低，其大倍率充放电性能得到改善，Ti4+掺杂效果更好；当掺杂量x＝0.025时，材料晶型完整，具有单一的a-NaFeO2层状结构；1C倍率时Li(Nil/3Col/3−0.025Mnl/3)Ti0.025O2的第二循环放电容量为143.2 mA∙h/g，2C时为128.0 mA∙h/g，经100次循环后容量分别为132.5和115.8 mA∙h/g，容量保持率为92.53%和90.47%。
关键字: LiNi1/3Co1/3 Mn1/3O2；锂离子电池；正极材料；电化学性能
（School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China）
Abstract:Cathode materials of Li(Nil/3Col/3−xMnl/3)MxO2(M=Ti, Mg) were prepared from oxalate precursor. The structures and morphologies of the synthesized samples were characterized by XRD and SEM. The electrochemical performance were tested by cyclic volt-ampere (CV), AC impedance and constant current/constant voltage charge-discharge measurement. The results show that the crystal volume of sample increases with the doping of Ti4+ or Mg2+. The electrochemical reaction resistant Rct decreases at high rates, thus improving the high rate charge-discharge properties of the materials. The effect of Ti4+ doped is better than that of Mg2+ doped. The sample is well crystallized and simple pure phase with a-NaFeO2 layered structure when doping quantity x=0.025. The second specific discharge capacity of Li(Nil/3Col/3−0.025Mnl/3)Ti0.025O2 is 143.2 mA∙h/g at 1C, 128.0 mA∙h/g at 2C, and still remains 132.5 and 115.8 mA∙h/g after 100 cycles, respectively, keeping capacity of 92.53% and 90.47%.
Key words: LiNi1/3Co1/3Mn1/3O2; lithium-ion batteries; cathode materials; electrochemical performance
