The effects of AC current on supercapacitor performance

Supercapacitor impedance spectra were found using AC currents for two types of supercapacitor: one containing a carbon aerogel and having a capacitance of 10 F and a maximum voltage of 2.5 V, and one containing activated carbon and an organic electrolyte and having a capacitance of 10 F and a maximum voltage of 2.3 V. Particular attention was paid to the region between 100 Hz and 100 kHz. This data was corrected by subtracting the impedance of the cables connecting the supercapacitor to the measurement hardware. The supercapacitor impedance was also measured using currents with both DC and AC components. The lowest impedance, and therefore the most efficient operating point, was found to be 10 kHz. This work has helped to identify an optimal working frequency for a power electronic converter to utilize a supercapacitor pack in an electric vehicle application.