锂离子电池负极材料Ge4+掺杂Li4Ti5O12的制备及其电化学性能研究

以Ti(OC₄H₉)₄、CH₃COOLi·2H₂O和GeO₂为原料, 采用溶胶-凝胶法合成了尖晶石型Li₄Ti_5-xGe_xO₁₂(x=0、0.05、0.1、0.15)电极材料。通过X射线衍射(XRD)、扫描电镜(SEM)、充放电测试、循环伏安(CV)以及交流阻抗对材料进行结构、形貌及电化学性能表征。研究结果表明, 适量Ge⁴⁺掺杂不会改变Li₄Ti₅O₁₂的尖晶石结构, 但对其颗粒尺寸和形貌均产生影响。由于掺Ge⁴⁺后样品的颗粒尺寸减小, 使得Ge⁴⁺掺杂Li₄Ti₅O₁₂倍率性得到不同程度的提高。其中Li₄Ti_4.9Ge_0.1O₁₂显示出较好的倍率性和循环稳定性, 0.2C下的首次放电容量为172.43 mAh/g, 5C下循环100次后比容量为140.62 mAh/g, 容量保持率为97.3%。

Preparation and Characterization of Ge4+-doping Li4Ti5O12 Anode Material for Li-ion Battery and Its Electrochemical Properties

The spinel Li₄Ti_5-xGe_xO₁₂ (x=0, 0.05, 0.1, 0.15) electrode materials were successfully synthesized by Sol-Gel method using Ti(OC₄H₉)₄, CH₃COOLi?2H₂O and GeO₂ as raw materials. The crystalline structure, morphology and electrochemical properties of the obtained materials were characterized by XRD, SEM, half cell charge-discharge tests, cyclic voltammetry (CV) and AC impedance. The results showed that doping with certain amount of Ge⁴⁺ did not change the basic structure of Li4Ti5O12, but greatly affected its mophology and particle size. Ge-doped Li₄Ti₅O₁₂ has relatively high rate capability due to the smaller particle size. In this study, Li₄Ti_4.9Ge_0.1O₁₂ represented the highest initial discharge capacity and the best cycling performance among all samples. At the charge-discharge rate of 0.2C, its first discharge capacity was 172.43 mAh/g, and at 5C rate, its discharge capacity remained at 140.62 mAh/g after 100 cycles with a capacity retention of 97.3%.