双电层电容器用新型无灰煤(HyperCoal)基活性炭的制备

以无灰煤(HyperCoal)为原料,KOH和CaCO3为活化剂制备了煤基活性炭,采用低温N2吸附法表征了活性炭的比表面积和孔结构,测定了活性炭用作双电层电容器(EDLC)电极材料的电化学性能。考察了炭化温度、活化温度、活化时间和活化剂对活性炭电容特性的影响。研究结果表明,比表面积和比电容随着炭化温度的升高而降低,活化温度过高或活化时间太长对比电容有不利影响。此外,CaCO3影响活化过程中孔的开发,显著降低所制备活性炭的比表面积和比电容。在炭化温度为500℃、活化温度为800℃、KOH与焦的质量比为4∶1和活化时间2 h下所得活性炭的比表面积和总孔容分别达到2 540 m2/g和1.65 cm3/g,该活性炭电极在0.5 mol/L TEABF4/PC电解液中的比电容达到最大值46.0 F/g。

Preparation of HyperCoal-based activated carbons for electric double layer capacitor

Coal-based activated carbons (ACs) were prepared from HyperCoal using KOH and CaCO₃ as activating agent, and were used as electrode materials for electric double layer capacitor (EDLC) using 0.5 mol/L TEABF4/PC as the electrolytic solution. The porosity of the ACs was characterized using N₂ adsorption at 77 K. The effects of carbonization temperature, activation temperature, activation time and activating agent on the capacitance characteristic of ACs were investigated. The results show that the specific surface area and the specific capacitance decreased with the increase of carbonization temperature. A high activation temperature and a long activation time is not beneficial for the specific capacitance of EDLC. CaCO₃ significantly inhibited the porosity development during KOH activation and gave ACs with quite low specific surface area and specific capacitance. The ACs prepared at carbonization temperature of 500 ℃, activation temperature of 800 ℃, KOH/char ratio of 4 and activation time of 2 h reached a specific surface area of 2 540 m²/g and a total pore volume of 1.65 cm³/g and achieved the maximum specific capacitance of 46.0 F/g.