The limited influence of transference number on the performance of nanoscale batteries

We present a model of a nanoscale Li-ion-type battery that includes explicit, atomistic representation of the current-carrying cations and their counter-ions. We use this model to simulate the dependence of battery performance on the transference number of the electrolyte. We report simulated values of the current at constant applied voltage for a series of model electrolytes with varying cation and anion mobilities. Unlike the predictions of macroscopic device models, our simulation results reveal that under conditions of fixed cation mobility, the performance of a nanoscale battery is not improved by increasing the transference number of the electrolyte. We attribute this model discrepancy to the ability of the electrolyte to support deviations from charge neutrality over nanometer length scales and conclude that models for nanoscale electrochemical systems need to include the possibility of deviations from electroneutrality.