On The Inverse Relaxation Approach To Supercapacitors Characterization
15 Pages Posted: 16 Aug 2019
Date Written: July 7, 2019
A distributed internal RC structure is observed in electrical measurements of the supercapacitors. The distribution is caused by the hierarchical porous structure of the electrodes. In the present work an inverse relaxation technique is proposed to characterization of the internal RC structure. The technique allows to determine the ratio of "easy" and "hard" to access capacitances. The method consists in shorting a supercapacitor (initially charged to a U₀) for a short (lower than the internal RC) time τ, then switching to the open circuit regime and measuring an initial rebound U₁ and a long--time asymptotic U₂. The main result is the possibility to find the ratio of "easy" and "hard" to access capacitances as η=(U₀-U₂)/(U₂-U₁). This characteristic is an immanent characteristic of a supercapacitor, it is stable in several orders of τ range. The theory is implemented numerically and tested on a number of model structures. The models are then compared to temporal and impedance measurements of commercial supercapacitors of several manufacturers. The approach can be effectively applied to characterization of supercapacitors and other relaxation type systems with porous internal structure.
Keywords: supercapacitors, inverse relaxation
JEL Classification: C02, C60
Suggested Citation: Suggested Citation