石油焦氧化改性制备活性炭及其电容性能研究

摘要

Petroleum coke (PC) was modified by H2O2 hydrothermal oxidization.Activated carbon (AC) was prepared by activation of H2O2 modified PC at KOH/coke mass ratio of 3 ∶ 1 (denoted as OAC-3).As a comparison,AC was also made by activation of PC at KOH/coke mass ratio of 3 ∶ 1,4 ∶ 1 and 5 ∶ 1 (denoted asAC-3,AC-4 and AC-5).X-ray diffraction (XRD),I2 adsorption,N2 adsorption and galvanostatic charge/discharge were used to study the influence of H2O2 oxidization on the structure of PC and the performance of the resulted activated carbon.XRD study revealed that H2O2 oxidization increased the interplanar distance of PC microcrystalline from 0.344 to 0.351nm and decreased the microcrystalline thickness from 2.34 to 1.86nm.The specific surface area of OAC-3 and AC 4 was 3066 and 2929m2/g,respectively.At a current density of 0.2A/g,OAC3 and AC-4 achieved a specific gravimetric capacitance of 374.6 and 338.9F/g,respectively.Electrochemical capacitors based on OAC-3 possessed a better power performance and lower resistance.%采用水热法,利用H2O2对石油焦进行氧化改性,以KOH为活化剂,在碱碳比为3∶1时将改性石油焦制备成活性炭(OAC-3);作为对比,在碱碳比为3∶1、4∶1和5∶1时将未改性石油焦制备成活性炭(AC-3、AC-4和AC-5).采用XRD、I2吸附、N2吸附和恒流充放电测试,研究氧化改性对石油焦和活性炭结构及性能的影响.研究表明,氧化改性使石油焦石墨微晶的晶面层间距由0.344nm增加到0.351nm,微晶厚度由2.34nm降低到1.86nm,降低了石油焦的活化难度.OAC-3和AC-4的比表面积分别为3066和2929m2/g;在0.2A/g的电流密度下,比电容分别为374.6和338.9F/g;基于OAC-3的超级电容器具有更好的功率特性和更低的内阻.