Resistance distribution in electrochemical capacitors with spiral-wound structure

The distribution of internal resistance in a Panasonic 10 F, 2.5 V electrochemical capacitor comprised of activated carbon electrode and organic electrolyte was analyzed. It was found that in the direction along the electrode surface, the resistance of the cell was mainly determined by the current collector and was 1.7 × 10^-3 Ω cm^-1. In the direction perpendicular to the electrode surface, the resistance was dependent on the applied pressure and a minimum resistance of 13.66 Ω cm² was obtained at an applied pressure of about 1 kg cm^-2. The resistance distribution at the applied pressure of 1 kg cm^-2 was 0.86, 1.91 and 8.11 Ω cm² contributing to the electrode carbon material, contact between the current collector and electrode and separator/electrolyte, respectively. A transmission line model was used to describe the cell resistance with dependence parameters, electrode length and the location of the electrical leads.