Parametric analysis of electrical storage materials: new concept and application

A generic non-linear circuit model based on transmission lines with elements representing kinetic steps in the electrochemical process of electrical storage system is established. Non-linear characteristics of parameters can be determined by measurements of wide-frequency-range impedance spectra at a number of different states of charge and by measurement of the emf-relation with subsequent mapping to the circuit model. A set of parameters can be represented as a “numerical image” of the electrical storage system, which enables us to simulate and predict discharge properties in time domain. As an exemplary application, parametric analysis of electrochemically polymerized porous polyaniline electrode suggests that kinetic steps dominating internal resistance of the system is related to intrinsic conductivity of the polymer. Power analysis shows that polyaniline can deliver high power density of 1400 W/kg at 3C rate with 75% of rate capability. Simulation of discharge potential is consistent with experiment with accuracy <2% of average deviation in discharge processes ranging from C/6 to 3C.