以月桂酸为分散剂,采用无水溶胶-凝胶法合成了高分散的Li_4Ti_5O_(12)纳米晶.采用XRD、SEM、TG-DSC、激光粒度分析仪、交流阻抗以及恒流充放电测试,对材料的形貌、结构和电化学性能进行表征.结果表明,煅烧温度对Li_4Ti_5O_(12)的结晶度、微观形貌及其电化学性能有显著的影响.800℃下热处理10h后的产物,颗粒尺寸细小均匀,约在120～275nm之间,显示出优异的电化学性能.在0.5和1C倍率下,首次放电比容量分别可达174.7和163.3mAh/g,经过50次放电循环后,放电容量循环性能优异.研究表明该高分散纳米颗粒的合成方法是适合制备高电化学性能的Li_4Ti_5O_(12)材料的工艺方法.
Nano-sized Li_4Ti_5O_(12) powder with high dispersivity was prepared by a novel sol-gel route using lauric acid as suffactant. The crystal structure, microstructure and the electrochemical properties of samples were characterized by XRD, FESEM, TG-DSC, laser particle size analysis, A.C. impedance and galvanostatically charge-discharge experiments. The results demonstrated that the crystallization, microstructure and electrochemical properties were influenced significantly by heat-treatment temperature. Li_4Ti_5O_(12) powders calcined at 800℃ for 10h were comprised of crystallites with the particle size in the range of 120-275nm,revealing high dispersivity almost without any agglomerates, and exhibiting an excellent electrochemical per-formance. Its discharge capacities at 0.5C and 1C rates were 174.7mAh/g and 163.3mAh/g, respectively.After 50 cycles, fairly stable cycling performance was achieved without obvious capacity fading. Electro-chemical impedance spectroscopy tests demonstrated that the surface reaction kinetics of Li_4Ti_5O_(12) was im-proved significantly from the state of the complete charge to the state of the complete discharge. The charge and discharge results of samples demonstrated that the route to synthesis highly dispersed nano-crystalline was appropriate for preparing Li_4Ti_5O_(12) with high electrochemical performance.
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