纳米级Li_(4)Ti_(5)O_(12)负极材料的制备及其输运特性

Preparation and transport property of nano-Li_(4)Ti_(5)O_(12) anode materials

以酞酸丁酯和乙酸锂为前驱体,通过溶胶凝胶法成功制备了纳米钛酸锂Li_4Ti_5O_(12)(LTO)负极材料。采用X射线衍射分析、扫描电镜(SEM)和透射电镜(TEM)分别对材料的物相与形貌进行了表征分析,并研究了煅烧条件和包覆改性对LTO输运特性的影响。研究表明,煅烧温度为800℃,时间为10 h条件下制备的样品的输运特性最佳,离子电导率为8.8×10^(-8) S/cm,电子电导率为8.53×10^(-10) S/cm。均匀的碳包覆层可以有效地改善样品的输运特性,LTO/C复合活性材料的离子与电子电导率分别达到4.35×10^(-7) S/cm和9.63×10^(-8) S/cm。电化学性能测试表明,碳包覆后的活性材料在0.1 C倍率下首次放电容量可达172.4 mAh/g;在5 C高倍率下循环充放电50次后,容量保持率可达94.4%,表现出较好的电化学性能。

Li_4Ti_5O_(12)(LTO)anode materials are successfully prepared by sol-gel method using butyl phthalate and lithium acetate as precursors.The phase and morphology of the material were characterized by X-ray diffraction,scanning electron microscopy and transmission electron microscopy.The effects of calcination conditions and coating modification on transport properties of LTO were also studied.The results show that the ionic conductivity and electronic conductivity of the sample prepared at 800℃and 10 h are 8.8×10^(-8) S/cm and 8.53×10^(-10) S/cm,respectively.The ionic and electronic conductivities of LTO/C are 4.35×10^(-7) S/cm and 9.63×10^(-8) S/cm,respectively.The electrochemical performance tests show that the first discharge capacity of carbon-coated active materials can reach 172.4 mAh/g at the ratio of 0.1 C.After 50 cycles at 5 C,the capacity retention rate can reach 94.4%,indicating a good electrochemical performance of the samples.