Li4Ti5O12/CMK-3复合材料的制备及其作为锂离子电池负极材料的性能

将LiNO₃和Ti(OC₄H₉)₄填填充在有序介孔碳CMK-3 孔道中, 然后烧结合成了Li₄Ti₅O₁₂/CMK-3复合材料. 利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线衍射(XRD)对其结构和微观形貌进行了表征. 利用差热-热重分析(TG-DTA)测试复合材料中Li₄Ti₅O₁₂的含量. 利用充放电测试、循环伏安和电化学阻抗技术考察了复合材料作为锂离子电池负极材料的性能. 发现Li₄Ti₅O₁₂分布在CMK-3孔道中及其周围, 复合材料的高倍率充放电性能显著优于商品Li₄Ti₅O₁₂, 复合材料中Li₄Ti₅O₁₂的比容量明显高于除去CMK-3的样品(在1C倍率时比容量为117.8 mAh·g^-1), 其0.5C、1C和5C倍率的放电比容量分别为160、143 和131 mAh·g^-1, 库仑效率接近100%, 5C倍率时循环100次的容量损失率只有0.62%. 本研究结果表明CMK-3明显提高了Li₄Ti₅O₁₂的高倍率充放电性能, 可能是CMK-3特殊的孔道结构和良好的导电性减小了Li₄Ti₅O₁₂的粒径并提高了其电导率.

Synthesis and Electrochemical Performance of Li4Ti5O12/CMK-3 Nanocomposite Negative Electrode Materials for Lithium-Ion Batteries

The composite of ordered mesoporous carbon (CMK-3) and Li₄Ti₅O₁₂ (Li₄Ti₅O₁₂/CMK-3) was prepared by the wet impregnation of CMK-3 with LiNO₃ and Ti(OC₄H₉)₄ solution followed by calcination. Its morphology and structure were examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The content of Li₄Ti₅O₁₂ in the mesoporous nanocomposite was determined by thermogravimetric analysis. Its electrochemical performance as the negative electrode material of lithium-ion batteries was investigated by galvanostatic charge-discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results show that Li₄Ti₅O₁₂ is formed inside the mesopore channels of CMK-3 and some particles are located on the surface of CMK-3. The composite shows significantly greater high-rate performance than commercial Li₄Ti₅O₁₂. The specific capacity of Li₄Ti₅O₁₂ in the composite is higher than Li₄Ti₅O₁₂ without CMK-3 (117.8 mAh·g^-1 at 1C rate), and its stabilized specific capacity reached 160, 143, and 131 mAh·g^-1 at 0.5C, 1C, and 5C charge-discharge rates, respectively, with a columbic efficiency of nearly 100%. The capacity loss after 100 cycles at 5C rate was less than 0.62%. This result clearly indicates that CMK-3 improves the high rate performance of Li₄Ti₅O₁₂, likely by reducing the particle size of Li₄Ti₅O₁₂ and increasing its electronic conductivity owing to the unique structure and good electronic conduction nature of CMK-3.