Memory and nonlinear transport effects in charging–discharging of a supercapacitor

We report on the results of analysis of the kinetics of charge–discharge current of Panasonic supercapacitors in a wide range of time from 10$^{-1}$ to 10$^4$ s. The non-Debye behavior of relaxation observed earlier by us and other authors is confirmed experimentally, and the influence of the supercapacitor charging regime on this process for various previous histories (values of applied voltage, charging time, and load resistance) is analyzed. The results are compared with available experimental data for paper–oil and electrolytic capacitors and with the results of calculations in the linear response model. It is found that in contrast to conventional capacitors, the response of the supercapacitor under investigation to variations of the charging regime does not match the linear response model. The relation of this nonlinearity to processes in the double electric layer, the morphology of the porous electrode, and the effect of charge reversal in pores is considered.