制备方法对尖晶石Li4Ti5O12负极材料的性质影响

Effect of Preparation Method on the Performance of Li4Ti5O12

摘要:

采用高温固相法、热聚合法和改良溶胶-凝胶法制备锂离子电池负极材料Li4Ti5O12。通过X-射线衍射、扫描电镜、恒电流充放电及电化学阻抗等技术和手段表征合成产物的结构、形貌及电化学性能。结果表明：溶胶-凝胶法合成的粉末为纯相Li4Ti5O12，而高温固相法和聚合法合成的Li4Ti5O12则存在TiO2杂相。高温固相法合成的Li4Ti5O12粉末晶粒最大，溶胶-凝胶法合成的粉末晶粒最小，分布最为均匀，晶粒尺寸约为80nm。高温固相法、热聚合法和溶胶-凝胶法制备的Li4Ti5O12粉末首次放电容量分别为161.6mAh/g、165.9mAh/g和171.5mAh/g，循环25次后的容量保持率分别为84.7%、87.7%和94.3%，溶胶-凝胶法合成的Li4Ti5O12粉末电化学性能最好。

Abstract:

Spinel Li4Ti5O12 powders are prepared by solid state reaction, thermal polymerization method and sol-gel. The phase identification, surface morphology, and electrochemical properties of the powders are investigated by X-ray diffraction, scanning electron microscopy, galvanostatic charge-discharge experiments and electrochemical impedance spectroscopy. The results show that the powders prepared by sol-gel are pure Li4Ti5O12. The powders prepared by solid state reaction and thermal polymerization method are impure with TiO2 phase. The grain size of the powders prepared by sol-gel is about 80 nm, which is much samller than the powders prepared by solid state reaction and thermal polymerization method. The capacities of the Li4Ti5O12 powders prepared by solid state reaction, thermal polymerization method and sol-gel are 161.6mAh/g, 165.9mAh/g and 171.5mAh/g, respectively. Their capacity retentions afer being cycled 25 times for the powders prepared by solid state reaction and thermal polymerization method are 84.7% and 87.7%, which are smaller than that of 94.3% for the powders prepared by sol-gel. The Li4Ti5O12 powders prepared by sol-gel shows the best electrochemical properties.