Abstract: In order to enhance electrical conductivity and rate capability of Li₄Ti₅O₁₂, the Li₄Ti₅O₁₂/C powder was prepared by the sol-gel method, using PEG as carbon source. The performance of Li₄Ti₅O₁₂/C coated by three different molecular weight carbon sources: PEG (400, 600, and 1000), was investigated with TG, XRD, SEM, TEM, constant current charge-discharge, rate discharge and EIS. The material obtained by using PEG1000 as carbon source had the best electrochemical performance. Initial discharge capacity was 143.5 mA·h·g^-1 at 0.1C rate, and discharge capacity remained 105 mA·h·g^-1 at 2C rate, capacity retention ratio was 73.17%, in addition, it had the smallest resistance.

Key words: electrochemistry, nanoparticles, powders, lithium ion battery, Li₄Ti₅O₁₂, PEG, sol-gel method

摘要： 针对Li₄Ti₅O₁₂导电性和倍率性能差的缺陷,以PEG为碳源采用溶胶-凝胶法制备出电池负极材料Li₄Ti₅O₁₂/C,考察不同分子量聚乙二醇PEG(400、600、1000)做碳源制备的Li₄Ti₅O₁₂/C复合材料电化学性能的优劣,采用热重分析仪(TG)、X射线衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)、恒流充放电、倍率放电、交流阻抗(EIS)等方法对材料进行了结构表征和电化学性能测试。结果表明:以PEG1000为碳源时得到的Li₄Ti₅O₁₂/C,0.1C下首次放电比容量为143.5 mA·h·g^-1,2C的倍率下仍然保持了105 mA·h·g^-1的比容量,容量保持率达到73.17%,并且此材料有最小的电阻,在大电流条件下有良好的电化学性能。

关键词: 电化学, 纳米粒子, 粉体, 锂离子电池, Li₄Ti₅O₁₂, PEG, 溶胶-凝胶法