Simulation of cyclic voltammetry in structural supercapacitors with pseudocapacitance behavior

Abstract

Cyclic voltammetry is an important technique to characterize the electrochemical performance and reaction kinetics in electrical and electrochemical energy storage devices under various conditions. In this study, a physics-based model is developed to simulate cyclic voltammetry measurements of reduced graphene oxide with aramid nanofiber (rGO-ANF) composite structural supercapacitors through multiphysics computational modeling and compared against experimental results. The presence of asymmetric forward and reverse sweeps in the cyclic voltammetry curves suggests pseudo-capacitance behavior associated with the oxygen-functionalized group. A multistep kinetics modeling approach is used to evaluate various kinetic processes that can occur at different potential values employing both Butler-Volmer and Tafel equations. Parametric studies were also performed to investigate the effects of scan rate, equilibrium potential, exchange current density, and transfer coefficient on cyclic voltammetry curves. The results demonstrate that nonzero equilibrium potential is more accurate for rGO-ANF supercapacitors and a low exchange current density of 10−6 A m−2 shows better agreement with the experimental measurements. The multistep modeling of cyclic voltammetry accompanied with experimental cyclic voltammetry curves provides a more accurate and comprehensive analysis of the kinetics and thermodynamics of structural supercapacitors and enables better design and control of device performance and life cycle.