溶胶-凝胶法制备Li4/3Ti5/3O4/Ag复合材料及其表征

Sol-gel Synthesis of Li4/3Ti5/3O4/Ag Composite and Its Performance as Anode for Lithium Ion Battery

摘要:

采用溶胶-凝胶法制备Li4/3Ti5/3O4/Ag复合材料，通过X-射线衍射、扫描电子显微镜、恒电流充放电及交流阻抗等技术检测和分析合成产物的物相、形貌及电化学性质。研究表明在Li4/3Ti5/3O4中添加银后Li4/3Ti5/3O4的Ti-O 键没受影响，Li4/3Ti5/3O4/Ag及Li4/3Ti5/3O4的晶格常数非常接近，银没有进入Li4/3Ti5/3O4晶格，只是均匀地分散在Li4/3Ti5/3O4颗粒中。与Li4/3Ti5/3O4相比, Li4/3Ti5/3O4/Ag 复合材料具有更高的比容量，更高的库仑效率以及更低的极化。添加银后对Li4/3Ti5/3O4锂离子扩散系数影响不大。电化学循环过程中，Li4/3Ti5/3O4/Ag的容量损失小于Li4/3Ti5/3O4，且随着充放电倍率的增加两者容量损失差距变大。Ag的添加大大地改善了Li4/3Ti5/3O4 的循环性能，尤其是大电流循环性能。

Abstract:

The powders of Li4/3Ti5/3O4/Ag composite were prepared by sol-gel technique. Phase identification, surface morphology and electrochemical properties were studied by X-ray diffraction, scanning electron microscopy, galvanostatic charge-discharge experiments, and electrochemical impedance spectroscopy. The results show that the Ti-O band is not affected by the addditive of Ag. Li4/3Ti5/3O4/Ag and Li4/3Ti5/3O4 have very similar crystal lattice parameters. Ag does not enter the Li4/3Ti5/3O4 crystal and disperses homogeneously in Li4/3Ti5/3O4 particles. Compared with Li4/3Ti5/3O4, Li4/3Ti5/3O4/Ag composite has higher specific capacity, higher columbic efficiency and lower polarization. The additive of Ag have little effect on the lithium ion diffusion of Li4/3Ti5/3O4. The capacity loss of Li4/3Ti5/3O4/Ag is smaller than that of i4/3Ti5/3O4 during cycling. The additive of Ag greatly improves the cycleability of Li4/3Ti5/3O4 powders, especially at higher charge-discharge rate.