二步煅烧法合成Li4Ti5O12材料的性能

采用超声活化对原材料Li2CO3和TiO2进行预处理,并采用二步煅烧方法制备Li4Ti5O12材料。利用X射线衍射仪、扫描电镜和电池充放电测试仪研究二步煅烧条件对材料结构、形貌及电化学性能的影响,并得到二步煅烧的最佳工艺。结果表明:采用600℃预烧温度制备的材料具有较高的纯度和结晶度;800℃高温煅烧温度下制备的Li4Ti5O12材料具有均一分散的颗粒结构;超声活化制备Li4Ti5O12的最佳煅烧工艺是600℃预烧8 h后800℃高温煅烧10 h,制备的材料在0.1C倍率下首次放电容量达170.6 mA.h/g,0.2C倍率下20次循环后的放电比容量由152 mA.h/g降至150 mA.h/g,容量保持率为98.7%。

Properties of Li4Ti5O12 synthesized by two-step calcination

Li2CO3 and TiO2 raw materials were pretreated by ultrasonic, then Li4Ti5O12 materials was prepared by two step calcination process. The effects of the synthesizing conditions on the crystalline structure, morphology and electrochemical properties were studied by XRD, SEM and cell charge/discharge performance test, and the best process was obtained. The results shows that the material synthesized at low calcined temperature of 600 ℃ shows a high crystallization and purity, the material synthesized at high calcined temperature of 800 ℃ shows a well-distributed structure. The best process for the preparation of Li4Ti5O12 is low calcined temperature of 600 ℃ for 8h sequentially high calcined temperature of 800 ℃ for 10 h, and the first discharge specific capacitance of the material at 0.1C is 170.6 mA-h/g, and after 20 cycles at 0.2C, the specific capacitance decreases from 152 mA-h/g to 150 mA-h/g with a retention rate of 98.7%.