ABSTRACT
Currents .......................................................................................100 4.10 Electrochemical Impedance Spectroscopy ........................................... 102
4.10.1 Equivalent Circuit Modeling .................................................... 104 4.10.2 Nyquist Plots .............................................................................. 105 4.10.3 Other EIS Plots ........................................................................... 106 4.10.4 Capacitance ................................................................................. 107
4.11 Constant Power Discharging .................................................................. 107 4.12 Constant Resistance Discharging ........................................................... 107 4.13 Potentiostatic Charge/Discharge ........................................................... 108 4.14 Life Cycle Testing ..................................................................................... 108 4.15 Self-Discharge ........................................................................................... 108 4.16 Potential Decay ......................................................................................... 109
4.16.1 Conway Models and the Rate-Determining Step of Self-Discharge Reactions ................................................... 109 4.16.1.1 Activation-Controlled Mechanism ......................... 110 4.16.1.2 Diffusion-Controlled Mechanism ........................... 110
In order for a material to be considered a supercapacitor, it should have electrochemical properties similar to that of a typical capacitor. This chapter describes the common measurement techniques used to evaluate the performance of a capacitive material or supercapacitor system. These techniques include cyclic voltammetry, galvanostatic charge/discharge, electrochemical impedance spectroscopy (EIS), self-discharge measurements, and others. A brief analysis of the typical experimental proles expected for each technique is provided, as well as a description of the method by which key supercapacitor descriptors can be calculated.
