锂离子电池负极材料Li4Ti5O12的半固相法制备及碳包覆改性

由半固相法制得锂离子电池负极材料Li4Ti5O12,并研究了Li4Ti5O12的碳包覆改性.采用XRD、SEM、TEM以及HRTEM观察和分析产物的相结构与形貌.采用恒流充放电、循环伏安法和交流阻抗技术测试了材料的电化学性质.结果表明,Li4Ti5O12因颗粒团聚电化学性能严重下降,该电极在0.1C和0.5C首周期放电容量分别为121.7和87.6 mAh·g-1;碳包覆Li4Ti5O12/C材料呈球形分布,能抑制颗粒团聚,该电极倍率<0.5C时的放电比容量大于180 mAh·g-1,超过Li4Ti5O12的理论放电比容量(175 mAh·g-1);在1C、5C和10C倍率下,其容量仍保持在136、79.9和58.3 mAh·g-1,碳包覆改性材料具有优异的循环寿命和高倍率性能.

Preparation and Modification of Li4Ti5O12 as Anode Materials for Lithium-Ion Batteries

Anode material Li4Ti5O12 for lithium-ion batteries was successfully prepared using half-solid-state method.Furthermore,carbon coating modification of Li4Ti5O12 was also carried out.The phase structure and morphology were analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM) and high resolution transmission electron microscopy(HRTEM).The electrochemical properties were investigated by constant current discharge-charge tests,cyclic voltammetry and electrochemical impedance techniques.The results indicated that the electrochemical performance of Li4Ti5O12 without modification declined seriously due to the aggregation of Li4Ti5O12 particles.The initial discharge capacities were only 121.7 mAh·g-1 at a rate of 0.1C and 87.6 mAh·g-1 at a rate of 0.5C.By means of carbon coating modification,the as-synthesized composite Li4Ti5O12/C kept the spherical morphology and showed no pronounced aggregation.At the charge-discharge rates less than 0.5C,the special capacities of Li4Ti5O12/C were always larger than 180 mAh·g-1 during cycling,exceeding the theoretical capacity of 175 mAh·g-1 for Li4Ti5O12.Moreover,the modified product exhibited high rate capacities of 136,79.9 and 58.3 mAh·g-1 at 1C,5C and 10C,respectively.All these results indicated that the carbon coating modification greatly enhanced the electrochemical performance of the product,which displayed excellent cycling stability as well as high rate performance.