La掺杂对523型镍钴锰酸锂正极材料电化学性能的影响

Effects of Lanthanum doping on electrochemical properties of 523-type Lithium Nickel-cobalt-Manganese oxide as positive electrode materials

文章研究了稀土元素La掺杂对镍钴锰酸锂Li Ni_(0.5-x)La_xCo_(0.2)Mn_(0.3)O_2(x=0,0.05,0.08,0.12)的物相和电化学性能的影响。利用液相共沉淀法+固相煅烧工艺制备了目标产物,并综合利用XRD、恒电流充放电技术及交流阻抗技术对材料物理和电化学性能进行了表征。La掺杂量x=0.05样品的首次放电比容量为152.6 mAh/g,库伦效率为93.6%,在1C电流密度下,经过30次电化学循环后的容量保持率为95.9%;在5C充放电电流密度下,掺杂样品的放电比容量为115.3 mAh/g,达到0.2C下放电比容量的76.4%。La掺杂增加了三元材料沿c轴方向的晶格常数,为锂离子在晶格内部的脱嵌提供了更大的空间,提高了锂离子在晶体中的扩散速度,从而显著增强了材料高倍率充放电性能。

The effect of lanthanum doping on the phase and electrochemical properties of lithium nickel-cobalt-manganese oxide LiNi0.5-xLaxCo0.2Mn0.3O2(x=0,0.05,0.08,0.12)was studied.The products were prepared by liquid co-precipitation and solid calcination,and characterized by XRD,galvanostatic charge/discharge and electrochemical impedance spectroscopy measurements.The first discharge specific capacity of the doped product with La x=0.05 reaches 152.6 mAh/g,and the Coulomb efficiency is 93.6%.The retention at 1C charge/discharge current density over 30cycles is 95.9%.At 5C current density,the specific discharge capacity of the doped sample retains115.3 mAh/g.Lanthanum doping can increase the lattice constant along the c-axis of lithium nickel-cobal-manganese oxide,and provide more space for the deintercalation of lithium ions in the lattice.Accordingly,the diffusion rate of lithium ion in the crystal is improved,and the high rate charge and discharge performance of the material is greatly enhanced.