关键词: 半固相法, Li4Ti5O12, 碳包覆, 锂离子电池

Abstract: 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, respectively. 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 180mAh.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 1, 5 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.

Key words: half-solid-state method, Li₄Ti₅O₁₂, carbon coating, lithium-ion battery