中间相炭微球负极预嵌锂量对软包装锂离子电容器性能的影响

摘要

以活性炭作为正极，预嵌锂的中间相炭微球为负极，制成软包装锂离子电容器。在正负极活性材料质量比为1∶1的条件下，采用恒压嵌锂法对负极进行预嵌锂，嵌锂容量分别为100 mA·h/g、200 mA·h/g、300 mA·h/g。在2～4V的电压区间内，对软包装器件进行倍率测试及高倍率下的寿命测试。测试结果显示，锂离子电容器单体电容量为4～5 F，预嵌锂容量为200 mA·h/g时电容器展现出最佳的电化学性能，首次充放电能量密度为83.7 W·h/kg （基于正负极活性质量），在倍率为120 C时，功率密度达8835.4 W/kg，能量密度保持在40.3 W·h/kg。在20 C的倍率下进行充放电寿命测试，500次循环之后，能量密度保持91.6%，1000次循环之后，能量密度保持86.5%。%Lithium ion capacitors (LIC) are fabricated in flexible packaging using activated carbon (AC) cathode and mesocarbon microbeads (MCMB) anode with mass ratio of 1∶1. We use constant-voltage pre-lithiation method and the capacity are 100 mA·h/g, 200 mA·h/g, and 300 mA·h/g, respectively. Rate capability and cycle life at high C-rates are evaluated at the potential range of 2.0—4.0 V. The results reveal that the capacitance of LIC monomer is between 4—5 F and the optimal electrochemical performance is obtained in the LIC with pre-lithiation capacity of 200 mA·h/g1. The first charge-discharge energy density is 83.7 W·h/kg (based on active material mass of two electrodes), the power density is 8835.4 W/kg and the energy density is 40.3 W·h/kg at 120 C rate. The cycle performance is tested at 20 C rate, the energy density retention is 91.5% after 500 cycles and 86.5%after 1000 cycles.