【摘要】 以商品活性炭(AC)为正极,预锂化中间相碳微球(LMCMBs)为负极,组装成锂离子电容器(LICs).用X射线衍射(XRD)对LMCMB电极材料的晶体结构进行了表征和分析,预锂化量(PIC)小于200mAh·g-1时,LMCMB电极材料基本保持了原始的石墨晶体结构.利用三电极装置,测试了充放电过程中LICs的正、负极及整电容器的电压变化曲线.以LMCMB为电极,锂离子电容器负极的工作电压变低,并且电压曲线更加平坦,同时正极也可以利用到更低的电压区间.对比锂离子电容器MCMB/AC,LMCMB/AC在比能量密度、循环性能和库仑效率电化学性能方面都得到了改善.在电压区间2.0-3.8V下,100次循环后,放电比容量的保持率从74.8%增加到100%,库仑效率从95%增加到100%.LMCMB/AC电容器容量不衰退的直接原因是由于AC正极极化变小.在2.0-3.8V和1.5-3.8V电压区间内,LMCMB/AC锂离子电容器的比能量密度分别可达85.6和97.9Wh·kg-1.更多还原

【Abstract】 Lithium ion capacitors (LICs) were fabricated using Li + -intercalated mesocarbon microbeads (LMCMBs) as the negative electrode and commercial activated carbon (AC) as the positive electrode. The phase structure of LMCMB electrodes was characterized by X-ray diffraction (XRD). LMCMB electrodes retain their original graphite crystal structure when the capacity induced by initial Li + intercalation is less than 200 mAh · g -1 . The charge-discharge performances of positive and negative electrodes and LICs were studied using a three-electrode cell. Using an LMCMB electrode as an anode, a stable working potential is obtained at lower voltage than using other electrodes, and the potential range of the positive electrode is extended to a lower range. The electrochemical performance of LMCMB/AC capacitors, including capacitance, cycle life, and efficiency, is improved compared with that of an MCMB/AC capacitor. The efficiency increases from less than 95% to nearly 100%, and the capacity retention is improved from 74.8% to nearly 100% for 100 cycles in a voltage range of 2.0 to 3.8 V. The stable capacity of LMCMB/AC capacitors with cycling is directly correlated to less polarization of AC during the charge storage process, which is caused in turn by the LMCMB negative electrode. Gravimetric energy densities as high as 85.6and 97.9 Wh · kg -1 are obtained in voltage ranges of 2.0 to 3.8 V and 1.5 to 3.8 V, respectively.更多还原