锂离子电池负极材料Ge^(4+)掺杂Li_4Ti_5O_(12)的制备及其电化学性能研究

Preparation and Characterization of Ge^(4+)-doping Li_4Ti_5O_(12)Anode Material for Li-ion Battery and Its Electrochemical Properties

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Li4Ti5-xGexO12(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Li4Ti4.9Ge0.1O12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%。

The spinel Li4Ti5-xGexO12（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,Li4Ti4.9Ge0.1O12 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%.