Reaction kinetics model in liquid and solid phases and its parameterization for room temperature sodium–sulfur battery

Abstract A multipore, multiphase, continuum model is assembled for the first time for room temperature sodium–sulfur (RT Na–S) batteries, with Na + ion transport and redox reactions in the liquid electrolyte phase and semisolid phase of precipitates softened by the electrolyte solvent, as guided by molecular dynamics simulations in this study. Experimental data of cyclic voltammetry (CV) and in operando UV–vis spectroscopy help elucidate which sulfides are produced during charge and discharge and lead to the development and fitting of a Na–S chain model of multiple redox reactions in electrolyte 1 M NaTFSI in TEGDME. The proposed reaction kinetics model is parameterized via the best fit between the predictions of the CV simulations and the experimental CV data for this RT Na–S cell. The model validation against the experimental data confirms the role of the semisolid precipitated sulfur and sulfides phase in the reaction chain of RT Na–S batteries.