Migration Effects on the Cyclic Voltammograms of the Electrodeposition/-Dissolution of Metal Anodes: A Simulation Study

Abstract Cyclic voltammograms (CVs) of metal electrodeposition/-dissolution reveal a characteristic waveform with a linear response in the reduction reaction for electrodeposition and a triangular oxidation wave for electrodissolution. To investigate the effect of migration on the characteristic waveform, the CV simulations of metal electrodeposition/-dissolution from monovalent and divalent cations were performed using the Nernst–Planck–Poisson equation. The characteristic metal electrodeposition/-dissolution CVs were successfully reproduced in the absence or low presence of a supporting electrolyte. The simulation results reveal that peak separation increases with decreasing supporting electrolyte/reactant ratio. In addition, in the absence of a supporting electrolyte, the CV waveform and migration potential at the plane of the electron transfer are independent of the reactant concentration. Even at sufficient electroactive electrolyte concentrations, migration potential is generated because of electroneutrality breakdown at the plane of the electron transfer. Moreover, migration potential causes severe kinetic hindrance in electron transfer, although to date such kinetic effects have typically been attributed to potential loss (ohmic loss) owing to decreases in the conductivity caused by insufficient electrolytes. In conclusion, migration is a critical factor in the CV analysis under insufficient supporting electrolyte conditions and in the development of metal anode batteries.