高性能Li_4Ti_5O_(12)的合成及其电化学性能研究

Preparation and Electrochemical Properties of High Performance Li_4Ti_5O_(12)

以无定型TiO2和氢氧化锂为原料,通过固相法合成了Li4Ti5O12.探讨了锂盐过量的质量分数和煅烧温度对Li4Ti5O12结构和电化学性能的影响,并通过XRD、SEM和恒电流充放电测试对其进行了表征.结果表明,当锂盐质量分数(ω)过量8%、煅烧温度为800℃时,得到了平均粒径为1.1μm的尖晶石型Li4Ti5O12,并具有最佳的电化学性能.0.1C倍率下首次放电比容量高达到170.18 mAhg-1,经过50次循环后放电比容量仍有139.81 mAhg-1,从第4次到第50次循环容量保持率为91.27%.当放电电流增大到1.0C时,首次放电比容量仍然保持在141 mAhg-1以上,经过50次循环后,比容量为107.33 mAhg-1,从第4次到第50次循环容量保持率仅为77.74%.

Li4Ti5O12 has been prepared via solid phase method using amorphous TiO2 and lithium hydroxide as starting materials. The influences of lithium salt excessive percentages and calcination temperature on the structure and electrochemical properties of Li4Ti3O12 are studied, and the properties of as-prepared sam pie are characterized by means of X-ray diffraction （XRD）, scanning electron microscope （SEM） and constant current charge-discharge. The results show that when lithium salt excessive percentage （co） is 8% and calcination temperature is 800℃, the spinel Li1Ti5O12 with average particle size of 1.1μm and the optimal electrochemical properties is obtained. The initial discharge specific capacity of the sample is as high as 170.18 mAhg-1 , which is still 139.81 mAhg-1 after 50 cycles at a current density of 0. 1C, the capacity retention rate is 91.27% during the 4～50th cycles. When the charge/discharge rate increases to 1.0C, the sample still remains initial discharge capacity of 141 mAhg i , and the discharge capacity is 107.33 mAhg-1 after 50 cycles, the capacity retention rate is 77. 74% during the 4～50th cycles. Key words： hydrothermal method; Li4Ti3O12, ; anode material of Li-ion batteries; amorphous TiO2