Analysis of cell impedance measured on the LiMn2O4 film electrode by PITT and EIS with Monte Carlo simulation

Cell impedance measured on a LiMn2O4 film electrode was analyzed by using the potentiostatic intermittent titration technique (PITT) and electrochemical impedance spectroscopy (EIS) with Monte Carlo simulation. The plot of the resistance of the absorption–desorption of lithium ions at the electrolyte ∣ electrode interface vs. the electrode potential measured by EIS coincided well with the plot of the cell impedance versus the electrode potential measured by PITT. The activation energy was determined experimentally from the temperature dependence of the resistance of the absorption–desorption of lithium ions. Both the resistance and the activation energy of the absorption–desorption of lithium ions, which were strongly dependent on the electrode potential, were analyzed by the kinetic Monte Carlo method involving transition state theory, taking into consideration the short-range interactions between lithium ions. From the comparison of the results measured experimentally and calculated theoretically, the rate-controlling step of the lithium intercalation into the LiMn2O4 film electrode was established.