无水溶胶-凝胶法合成Li_4Ti_5O_(12)纳米晶及性能研究

Synthesis and electrochemical properties of Li_4Ti_5O_(12) nano-crystalline by nonaqueous sol-gel method

以月桂酸为表面活性剂,通过无水溶胶-凝胶法合成了高分散的Li4Ti5O12纳米晶。采用XRD、SEM、TG-DSC以及恒流充放电测试等手段对材料的形貌、结构和电化学性能进行表征。通过研究Li/Ti摩尔比、表面活性剂的量及煅烧温度对物相结构、颗粒形貌及电化学性能的影响,优化制备工艺。结果表明,表面活性剂的量对Li4Ti5O12的微观形貌及其电化学性能有显著的影响。800℃热处理10h后的产物,颗粒尺寸在100～300nm之间,基本无团聚,具有较好的分散性,显示出优异的电化学性能,1和2C下,首次放电容量分别为163.3和132.3mAh/g,50次放电循环后,放电容量无明显衰减。

Nano-sized Li4Ti5O12 powders with high dispersivity were prepared by a novel sol-gel route using lauric acid as surfactant.The crystal structure,microstructure and the electrochemical properties of the samples were characterized by XRD,SEM,TG-DSC and galvanostatically charge-discharge experiments.The effects of molar ratio of Li to Ti,the content of surfactant and the calcining temperature on the phase structure,the microstructure and the electrochemical properties were studied to optimize process.The results demonstrated that the crystallization,microstructure and electrochemical properties were influenced significantly by the content of the surfactant.Li4Ti5O12 powders calcined at 800℃ for 10h comprised of crystallites with the particle size in the range 100-300nm revealing high dispersivity almost without any agglomerates,exhibiting an excellent electrochemical performance.Its discharge capacity at 1 and 2C rates can reach 163.3 and 132.3mAh/g,respectively.After 50 cycles,fairly stable cycling performance was achieved without obvious capacity fade.