采用循环伏安法研究微孔型多孔炭电极的电容特性

Capacitance characteristic of porous carbon electrodes with micropores studied by cyclic voltammetry

以酚醛树脂为原料,KOH为活化剂,制备出3种不同孔径分布的微孔型多孔炭(孔径≤2 nm)。在低温氮气吸附法测定BET比表面积和孔结构的基础上,采用循环伏安法考察了这3种微孔型多孔炭作电极的双电层电容器(EDLC)的电容特性。实验结果表明,微孔型多孔炭作电极的EDLC的电容特性是:在低扫描速率下,其循环伏安曲线达到电容平台后在高电压(±1.0 V)附近出现峰电容;延长在电解液中的浸渍时间,电极的比电容增大,高电位附近的峰电容减小。3种不同孔径分布的微孔型多孔炭作电极的EDLC的循环伏安特性受浸渍时间影响的程度也不同。

Three porous carbons with different micropore distribution, prepared from phenolic resins activation by various mass fraction of KOH, were applied in electric double-layer capacitor （EDLC）. The BET specific surface areas and pore structure parameters of three porous carbons obtained were determined by the nitrogen gas adsorption isotherm. And the capacitance charicteristics of EDLC used three porous carbons were studied by cyclic vohammetry （CV）. The results show that the cyclic voltammogram of the EDLC used porous carbons with micropore appears capacitance peak near high voltage （±1.0 V） after arriving capacitance flat at small scan rate, which is different from the cyclic vohammograms of porous electrode with macropore and mesopore. Moreover the specific capacitance of porous carbons with micropore mainly increases while the capacitance peak near high voltage decreases when the soakage time of porous carbon electrode in KOH electrolyte is prolonged. The influences of soakage time on cyclic vohammogram of EDLC with three porous carbons obtained are different due to the different micropore distribution.