Parametric analysis of electrical storage materials: new concept and application

A generic non-linear circuit model based on transmission lines with element s representing kinetic steps in the electrochemical process of electrical s torage 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-relati on 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 polymer ized porous polyaniline electrode suggests that kinetic steps dominating in ternal resistance of the system is related to intrinsic conductivity of the polymer. Power analysis shows that polyaniline can deliver high power dens ity of 1400 W/kg at 3C rate with 75% of rate capability. Simulation of disc harge potential is consistent with experiment with accuracy <2% of average deviation in discharge processes ranging from C/6 to 3C. (C) 2001 Elsevier Science B.V. All rights reserved.