活性碳纳米管的制备及其在有机电解液中的电容性能研究

以KOH为活化剂对碳纳米管进行化学活化制备双电层电容器用高比表面积活性碳纳米管. 采用TEM和N₂吸附法表征活性碳纳米管的结构, 采用恒流充放电、循环伏安、交流阻抗等评价其在1 mol?L^－1 Et₄NBF₄/PC中的电容性能. 随活化剂用量增大、活化温度升高和活化时间的延长, 活性碳纳米管的比表面积和比电容都呈增大的趋势. 活化剂用量为3∶1, 800 ℃活化4 h制备的活性碳纳米管的比表面积663 m²?g^－1, 比活化前提高了3倍, 其比电容达57.2 F? g^－1, 比活化前提高了2倍. 将活性碳纳米管的比电容与其比表面积相关联, 发现两者之间具有非常好的线性关系, 并分析了原因.

Preparation of Activated Carbon Nanotubes and Their Electro-chemical Capacitive Performance in Organic Electrolyte

Activated carbon nanotubes (ACNTs) with high surface area have been successfully prepared from carbon nanotubes by KOH activation for electric double layer capacitors. The microstructure of the ACNTs was characterized by TEM and nitrogen adsorption isotherms. The electrochemical capacitive performances of the ACNTs in 1 mol?L^－1 Et₄NBF₄/PC electrolyte were evaluated with cyclic voltammetry (CV), galvanostatic charge/discharge and ac impedance spectroscopy, etc. When the amount of activation agent increased, or the activation temperature rose, or the activation time was prolonged, the specific surface area and the capacitance of the ACNTs all showed an increasing tendency. The surface area of the ACNT sample prepared by KOH activation with KOH/C ratio of 3∶1 at 800 ℃ for 4 h reached 663 m²?g^－1, three times larger than that of the pristine non-activated carbon nanotubes. Its specific capacitance reached 57.2 F?g^－1, three times as large as that of the non-activated carbon nanotubes. It was found that there was a linear dependence of the capacitance on their BET surface area for activated carbon nanotubes.