Y3+掺杂Li4Ti5O12负极材料的电荷输运特性及电化学性能研究

以Li₂CO₃与锐钛矿型TiO₂为原料，六水合硝酸钇（Y（NO₃）₃·6H₂O）为钇源，采用球磨辅助固相法合成了Li₄Ti_5-xY_xO₁₂（x=0，0.05，0.10，0.15，0.20）负极材料。通过X射线衍射分析（XRD）、扫描电镜（SEM）、能谱仪（EDS）与X射线光电子能谱（XPS）分别对材料的物相与形貌进行表征分析，并利用电化学工作站对材料的电化学性能与电荷输运特性进行测试。结果表明，Y³⁺掺杂没有影响尖晶石型Li₄Ti₅O₁₂（LTO）材料的尖晶石结构，x=0.15时，Li₄Ti_4.85Y_0.15O₁₂样品的离子与电子电导率分别为2.68×10^-7 S·cm^-1和1.49×10^-9 S·cm^-1，比本征材料提升了1个数量级，表现出良好的电荷输运特性。电化学测试表明，Li₄Ti_4.85Y_0.15O₁₂样品在0.1 C倍率首次放电比容量可达171 mAh·g^-1，且在10 C与20 C高倍率下仍然拥有102 mAh·g^-1和79 mAh·g^-1的较高比容量，循环200周次后容量保持率分别为92.6%和89.1%，表现出良好的倍率特性。

Transport characteristics and electrochemical properties of Y3+ doped Li4Ti5O12 as anode material

Li₄Ti_5-xY_xO₁₂ (x=0, 0.05, 0.10, 0.15, 0.20) anode materials were synthesized by ball milling assisted solid-state method used Li₂CO₃ and anatase TiO₂ as raw materials and yttrium nitrate (Y(NO₃)₃·6H₂O) as yttrium source. The phase and morphology of the materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), respectively. The electrochemical performance and transport characteristics of the materials were tested and analyzed by an electrochemical workstation. The results show that there is no effect of Y³⁺ doping on the spinel structure of LTO material. When x=0.15, the ion and electronic conductivities of the Li₄Ti_4.85Y_0.15O₁₂ sample are 2.68×10^-7 S·cm^-1 and 1.49×10^-9 S·cm^-1, respectively, which are an order of magnitude higher than that of the intrinsic LTO, and present good transport characteristics. Electrochemical tests show that a first discharge capacity of Li₄Ti_4.85Y_0.15O₁₂ sample can reach 171 mAh·g^-1 at 0.1 C rate. The sample still has a higher specific capacity of 102 mAh·g^-1 and 79 mAh·g^-1 at a high rate of 10 C and 20 C, respectively.After 200 cycles, the capacity retention rates are 92.6% and 89.1% respectively, showing good magnification characteristics.