Comprehensive Approach to Atomistic Simulations of Discharging Batteries

Abstract

Predicting the performance of batteries using analytical and computational models plays an important role in the design of battery packs and management systems. Currently, these models rely on extensive experimental parametrization; but fundamentally, these parameters arise from atomistic interactions between components of the electrolyte and the resulting correlated motion of the ions. In this work, we demonstrate a comprehensive approach to atomistic simulations of discharging batteries, evaluating electrochemical potential gradients in the electrolyte and using Onsager mobility coefficients to relate the resulting forces to the flux of lithium ions between the electrodes. This work unifies four different sets of simulations: (1) mobility, which observes the molecular flux of species in response to constant forces; (2) thermodynamic susceptibility, which observes the response of species concentration to external potentials; (3) bulk modulus, which observes the density response to pressure; and (4) battery discharge, which generates a steady flux of cations and observes the resulting concentration and potential gradients. The resulting model self-consistently describes ion-transport battery electrolytes.