炭气凝胶/活性炭复合电极在有机电解液体系双电层电容器中的阻抗

分别以炭气凝胶(CAG),炭黑(CB)以及石墨(G)为导电剂与KOH活化法高比表面积活性炭(HSAC)制备复合电极,组装成双电层电容器,在(C2H5)4NBF4/丙烯碳酸盐电解液体系中进行交流阻抗测试分析。应用动力学及电子传递控制的等效电路模型对各电极的实验阻抗数据进行拟合得到相应的模型参数,串联溶液电阻Rs、极化电阻Rp、能斯特边界层厚度δ及平均孔内离子扩散系数D。结果表明,炭气凝胶复合电极的孔内离子扩散系数D最高,极化电阻Rp与炭黑复合电极接近。炭气凝胶电极的内阻为各电极中最低并且具有最高的比电容。

Impedance of carbon aerogel/activated carbon composites as electrodes of electrochemical capacitors in aprotic electrolyte

Carbon aerogel (CAG), carbon black (CB), and graphite (G) were added to a high surface area activated carbon (HSAC), prepared by KOH activation, to form composites for use as electrodes of electrochemical capacitors(ECs). The performance of the ECs using these electrodes in (C2H5)4NBF4/propylene carbonate electrolyte were ana lyzed and compared by an electrochemical impedance spectrum (EIS). An equivalent circuit model with mixed kinetic and charge transfer control was assumed and a Marquardt fit procedure was applied to the EIS data, from which model parameters, such as, series solution resistance, Rs, polarization resistance, Rp, Nernst diffusion layer thickness, δ, and average value of the diffusion coefficients of electrolyte ions, D, were extracted and compared for CAG-, CB-, and Gbased composites. It was found that the ECs using CAG had the highest D values and a comparable Rp value with CB.The CAG-based composite had the lowest resistance and highest capacitance at the same frequencies among the three types of composites investigated.