Synthesis and Electrochemical Properties of Highly Dispersed Li_4Ti_5O_(12) Nano-crystalline as Anode Material for Lithium Secondary Batteries

Nano-sized Li4Ti5O12 powder with high dispersivity was prepared by a novel sol-gel route using lauric acid as surfactant.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.Li4Ti5O12 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 performance.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.Electrochemical impedance spectroscopy tests demonstrated that the surface reaction kinetics of Li4Ti5O12 was improved 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 Li4Ti5O12 with high electrochemical performance.