Abstract:

Lithium titanate (LTO) samples were prepared by solid phase method, and then LTO and graphene oxide were treated by hydro-thermal method to prepare lithium titanate/graphene oxide composite (LTO-RGO). The structure and morphology of the material were characterized by XRD, SEM and TEM, and its electrochemical properties were tested by charge-discharge performance test and AC impedance test. The results showed that the graphene coating treatment of lithium titanate had no effect on the crystal structure of lithium titanate and no impurities appeared. LTO-RGO exhibited excellent electrochemical performance. The discharge specific capacity at 0.2C ratio was 208.7mA·h/g, the capacity retention rate after 50 cycles was 98.10%, and the discharge specific capacity at 20C ratio was 136.1 mA·h/g.

Key words: solid phase method, hydro-thermal method, graphene oxide, rate cycling, AC impedance, coefficient of diffusion

摘要：

通过固相法制备出钛酸锂(LTO)样品，再将LTO和氧化石墨烯通过水热法制得钛酸锂/还原石墨烯复合材料(LTO-RGO)。通过XRD、SEM、TEM对材料的结构、形貌进行表征，并进行充放电性能测试、交流阻抗测试来检测其电化学性能。结果表明，石墨烯对钛酸锂进行包覆处理不影响钛酸锂材料的晶型结构、无杂相出现。钛酸锂/石墨烯复合材料表现出了比钛酸锂材料更为优异的电化学性能，0.2C倍率下的放电比容量为208.7mA·h/g，50次循环后容量保持率为98.10%；20C倍率下的放电比容量为136.1mA·h/g。

关键词: 固相法, 水热法, 氧化石墨烯, 倍率循环, 交流阻抗, 扩散系数