以预锂化多壁碳纳米管为负极的锂离子电容器性能

采用内部短路方式对多壁碳纳米管负极进行不同程度的预嵌锂处理,预嵌锂时间为5,30,60min,以预嵌锂多壁碳纳米管极片作为负极,活性炭极片作为正极,组装成锂离子电容器。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)对多壁碳纳米管及电极极片进行表征分析,采用恒流充放电(GCD)和交流阻抗谱(EIS)研究预嵌锂多壁碳纳米管负极和未预嵌锂处理多壁碳纳米管负极锂离子电容器的性能。电化学测试结果表明,多壁碳纳米管负极预嵌锂大幅提高了电容器充放电性能,对比未嵌锂多壁碳纳米管电容器,在相同的电流密度下(100mA/g),能量密度提高400%。预嵌锂60min,电流密度100mA/g时,其比容量达到57F/g。在电流密度为100～3200mA/g范围内,其最高能量密度与功率密度分别达到90Wh/kg,4130W/kg。1000次充放电循环后,容量保持率维持在85%以上,表现出良好的超级电容器性能。

Performance of lithium-ion capacitors using pre-lithiated multiwalled carbon nanotubes as negative electrode

Pre-lithiated multiwalled carbon nanotube anode was prepared by internal short approach(IS) for 5min, 30min and 60min. Lithium ion capacitors (LICs) were assembled using pre-lithiated multiwalled carbon nanotubes as cathode and activated carbon(AC) as anode. The structure characterization of multiwalled carbon nanotubes and electrodes were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical performance of pre-lithiated multiwalled carbon nanotube electrodes and pure multiwalled carbon nanotubes electrodes were tested by galvanostatic charge/discharge and electrochemical impedance spectrum. The electrochemical tests indicate that the charge-discharge performance of LIC is greatly improved by pre- lithiation of multiwalled carbon nanotubes. The energy density reaches about 4 times over conventional electric double-layer capacitors (EDLCs) at the current density of100mA/g. The LICs achived a specific capacitance of 57F/g at the current density of100mA/g with 60min pre-lithiatiation process. The maximum energy density and power density reach 90Wh/kg and 4130W/kg respectively in the current range of100-3200mA/g. The capacity retention rate remains more than 85% after1000 cycles. The LIC shows excellent supercapacitor performance.