沥青基多孔炭材料制备及其双电层储能性能

Preparation of coal tar pitch-based porous carbon materials and their electric double-layer energy storage performance

多孔炭作为超级电容器电极的主要材料,具有导电性好、化学稳定性高、工作温度范围广等优点。以内蒙古煤沥青(CTP)为原料,分别以K_(2)CO_(3)和KOH为活化剂,通过化学活化法制备多孔炭材料,优化制备工艺并比较2种活化剂制备的多孔炭在结构和电化学性能方面的差异。结果表明,K_(2)CO_(3)活化和KOH活化最佳制备条件均为活化温度700℃、活化时间60 min、活化剂与CTP质量比为2∶1。2种活化剂制备的多孔炭在微观结构上有很大差异,KOH活化所得多孔炭(PH-T700)表面平整光滑并分布大量规则的圆孔,而K_(2)CO_(3)活化所得多孔炭(PC-T700)内部呈层叠交错的珊瑚状结构。与PH-T700相比,PC-T700具有更多中孔,离子扩散阻力更小。在1 A/g电流密度下,PC-T700和PH-T700的比电容量分别为252.90和261.02 F/g,PC-T700和PH-T700组装成纽扣型对称电容器,0.5 A/g时比电容量分别为226.01和225.51 F/g,且PC-T700表现出更优秀的倍率性能和循环稳定性。5000次充放电后,PC-T700和PH-T700的比电容量分别为初始值的103.77%和98.20%。输出功率达1038.46 W/kg时,PC-T700能量密度仍保持7.5 Wh/kg,实际使用价值高于PH-T700。

As main material for supercapacitor electrodes,porous carbon has the advantages of good electrical conductivity,high chemical stability and wide range of operating temperature.In this paper,porous carbon materials were prepared by chemical activation using Inner Mongolia coal tar pitch(CTP)as raw material,K_(2)CO_(3)and KOH as the activators respectively.The preparation process conditions were optimized,and the differences in structure and electrochemical performance of the porous carbon prepared by the two activators were compared.The results show that the optimal preparation conditions for K_(2)CO_(3)and KOH activation are both activation temperature of 700℃activation time of 60 min,and mass ratio of activator to CTP of 2∶1.There are significant differences in the microstructure of porous carbon prepared by the two activators.The surface of porous carbon(PH-T700)prepared by KOH activation is flat and smooth,with a large number of regular circular pores distributed,but the porous carbon(PC-T700)obtained by K_(2)CO_(3)activation shows a coral structure.Compared with PH-T700,PC-T700 has more mesopores and less ionic diffusion resistance.At a current density of 1 A/g,the specific capacitance of PC-T700 and PH-T700 are 252.90 and 261.02 F/g,respectively.PC-T700 and PH-T700 are assembled into button type symmetrical capacitors,with specific capacitance of 226.01 and 225.51 F/g at 0.5 A/g,respectively.PC-T700 shows better rate capability and cycling stability.After 5000 times of charging and discharging,the specific capacitance of PC-T700 and PH-T700 are 103.77%and 98.20%of the initial values,respectively.When power density reaches 1038.46 W/kg,the energy density of PC-T700 still maintains 7.5 Wh/kg,which is higher than that of PH-T700.