Modelling of Voltammetric Data from Electrochemical Capacitor Electrodes

Abstract

Many techniques have been used to characterize materials used in electrochemical capacitor electrodes. This includes the suite of materials science techniques to assess material structure, morphology, conductivity, etc., as well as various electrochemical techniques to assess material and electrode performance and cycling mechanisms. In the domain of electrochemical characterization methods techniques such as cyclic voltammetry and constant current charge-discharge cycling are used commonly to assess performance and gain an introductory insight into electrochemical mechanisms. Other techniques such as electrochemical impedance spectroscopy and step potential electrochemical spectroscopy also provide substantial mechanistic information. This work is focused on enhancing the information that can be extracted from voltammetric data on electrochemical capacitor electrodes. Contributions to the overall current response are made from: 1. Capacitive processes, as modelled using the series combination of a resistor and capacitor; 2. Kinetically limited processes, as modelled using the Butler-Volmer equation; 3. Solid state redox processes, as modelled using an experssion derived from the Nernst equation; and 4. Electrode resistance