Effect of Metal Electrode and Concentration Redox Couple Effect on Electrical Circuit Parameters for Heterocharge System: Potential Application for Lithium-Ion Battery

Abstract

The analytical solution has been expanded to describe the circuit parameters of a redox couple with a charge of +1 and 0 for electrochemical reaction in the presence of supporting electrolyte as a potential application in lithium-ion battery. The Gouy–Chapman–Stern theory has been developed to comprehend the capacitance behavior as a function of the difference in electrical potential between the solution and metal parameters (E_eq variable). Finite-element simulations have been employed to explore various electrochemical system configurations, enhancing electrical storage energy by engineering the types of metal electrode and concentration heterocharge redox couple and supporting electrolyte. The initial guess for the Randles circuit parameters has been implemented by Matlab code developing, deriving them from the electrical current response versus time in a frequency-dependent sinusoidal wave function. Subsequently, the optimization problem regarding fitting of the circuit parameters has been performed through open-source Python code for electrochemical impedance spectroscopy using the initial Randles circuit parameter guess. The semianalytical method revealed a minimum in capacitance behavior near the zero value of the E_eq variable. Additionally, the numerical method showed that the capacitance behavior regarding the E_eq variable remains constant for high concentrations of the supporting electrolyte. The charge transfer coefficient demonstrated a monotonic behavior versus E_eq for all electrochemical reactions occurring on the parallel microdisk. A simulation result regarding general trend for capacitance versus E_eq variable is consistent with the available experimental data.