【作者】 郭雪飞；

【导师】 王成扬；

【作者基本信息】 天津大学 ， 化学工艺， 2007， 硕士

【摘要】 电化学混合电容器（EHC）是一种介于超级电容器和电池之间的新型贮能元件,它具有比超级电容器更高的比容量和比能量及比电池更高的功率密度,是混合动力车、动力电源的最佳选择之一。其材料和体系的构筑是研究的重点。本课题以活性炭为正极,锂离子嵌入材料Li₄Ti₅O₁₂为负极组成AC/Li₄Ti₅O₁₂电化学混合电容器体系,对其电化学性能进行了研究,恒流充/放电、循环伏安以及交流阻抗等测试显示出该混合电容器体系具有良好的电化学性能。用高温固相法和熔盐法制备出具有尖晶石结构的Li₄Ti₅O₁₂,XRD和SEM测试表明两种合成产物都具有较高的相纯度和优良的晶型。其中用高温固相法制备出的Li₄Ti₅O₁₂电极具有很宽的充放电平台,循环性能稳定,以30mA·g-1的电流密度恒流充/放电,比容量达到128.8mAh·g-1,效率达到98.2%。以高比表面积活性炭为正极,高温固相法合成的Li₄Ti₅O₁₂为负极,电解液为1M LiClO4/PC组装成的AC/Li₄Ti₅O₁₂混合电容器电化学性能最佳,正负极活性物质质量比为3:1时混合电容器的总质量比容量达到29.2mAh·g-1（电流密度为50mA·g-1）,且得到最优效率98.6%,其最佳工作电压区间为1.5～2.8V,循环性能和大电流充放电性能良好。AC/Li₄Ti₅O₁₂混合电容器工作电压约为2.25V,比能量可达到67.5Wh·kg-1。循环伏安扫描测试表明AC/Li₄Ti₅O₁₂混合电容器电化学性能是由AC正极的非法拉第过程和Li₄Ti₅O₁₂负极的法拉第过程的电化学特性共同决定的。交流阻抗测试发现,AC/Li₄Ti₅O₁₂电容器在不同嵌锂程度下阻抗有极大差别,这与不同状态时Li₄Ti₅O₁₂的电导率有一定关系。对以活性炭为正极,锂离子电池炭负极材料中间相炭微球（MCMB）为负极的电化学混合电容器进行了初步的电化学性能的研究,50mA·g-1电流密度下放电比容量达到30.4mAh·g-1,充/放电效率为91.6%。更多还原

【Abstract】 The electrochemical hybrid capacitors（EHC） is a novel storage device between supercapacitor and battery, with more specific capacitance and energy density compared with supercapacitor and more power density compared with battery, it’s one of the optimum choices for hybrid electrochemical vehicles and power sources. The focus is the electrode materials and the system construction. AC/Li₄Ti₅O₁₂ electrochemical hybrid capacitor was assembled using an activated carbon cathode and an intercalation compound Li₄Ti₅O₁₂ anode, and it was investigated by means of constant charge/discharge, cyclic voltammetry and electrochemical impedance spectroscopy measurements.The spinal phase Li₄Ti₅O₁₂ was prepared with high-temperature solid-state method and molten salt method, and the XRD and SEM measurements showed that the both productions exhibited high phase purity and good crystallite. The Li₄Ti₅O₁₂ synthesize by high-temperature solid-state method has wide charge/discharge plateau and stable cyclic performance, with a specific capacitance of 128.8mAh·g-1 at 30mA·g-1 current, and the cycle efficiency reached to 98.2%.The AC/Li₄Ti₅O₁₂ hybrid capacitor, consisted of a high specific surfance area AC cathode and a Li₄Ti₅O₁₂ anode synthesize by high-temperature solid-state method in 1M LiClO4/PC, exhibits a good electrochemical performance. The capacitor (mAC/mLi₄Ti₅O₁₂=3:1) delivers a specific capacitance of 29.2mAh·g-1（based on the total weight of the electrod materials） at 50mA·g-1 current, and the cycle efficiency reached to 98.6%. The capacitor also has a sloping profile from 2.8 to 1.5V, and it exhibits a good cycling profile and desirable high rate capability. The hybrid capacitor delivers a specific energy of 67.5Wh·kg-1 based on the total active materials, the working volage is 2.25V. The CV curves showed that simultaneous with nonfaradic reaction in AC cathode, a faradic reaction occurred on Li₄Ti₅O₁₂ anode. AC impedance spectra of the capacitor at charge/discharge potentials shows that electrochemical impedance was possibly infltenced by the corresponding conductivity at Li+ insertion extend.The hybrid capacitor using AC as cathode and MCMB as anode was developed, and the electrochemical performace was studied primarily. The AC/MCMB capacitor delivers a specific capacitance of 30.4mAh·g-1 at 50mA·g-1 current, and the cycle efficiency is 91.6%.更多还原