高分散Li4Ti5O12纳米晶的制备及电化学性能

摘要

以月桂酸为分散剂,采用溶胶-凝胶法合成颗粒尺寸为120～250 nm的高分散Li4Ti5O12纳米晶.通过研究表面活性剂月桂酸的含量优化制备工艺,制备出电化学性能最佳的样品.采用XRD、FESEM、TEM、激光粒度分析仪、交流阻抗以及恒流充放电测试,对材料的物理和电化学性能进行表征.在800℃下热处理10h后的高分散性Li4Ti5O12纳米晶显示出优异的电化学性能,在1C倍率下,首次放电容量为163.3 mA·h/g,50次放电循环后,放电容量无明显衰减.研究表明,高分散性Li4Ti5O12纳米晶可以缩短锂离子的扩散路径,改善样品的电化学动力过程,有效地提高其高倍率性能.%A sol-gel method using lauric acid as surfactant was used to synthesize Li4Ti5O12 nanocrystals with an ultra-fine particle size distribution between 120 and 250 nm.In order to obtain the electrode materials with the best electrochemical performance,the content of lauric acid during Li4Ti5O12 synthesis was systematically studied.The physical and electrochemical properties of the synthesized samples were characterized by X-ray diffraction (XRD),field emission scanning electron microscopy (FESEM),transmission electron microscopy (TEM),laser particle size analysis,alternating current impedance (AC) and galvanostatic charge-discharge experiments.The highly dispersed Li4Ti5O12 nanocrystals obtained at 800 ℃ for 10 h can deliver a specific capacity of 163.3 mA·h/g at 1C rate without obvious capacity fade up to 50 cycles.The results suggest that well dispersed Li4Ti5O12 nanocrystals shorten the Li-ion diffusion length and enhance the electrochemical kinetics of the samples,which are very crucial to high rate capability.