Atomistic model of discharging batteries

Computational models of batteries are essential in making critical design choices that determine the performance and longevity of batteries. These models focus on different aspects of battery operations, ranging from electrochemical reaction rates, degradation of electrodes or electrolytes, ion transport through electrolytes, to heat generation and dissipation in large battery packs. Most of these models rely on experimentally measured transport properties and overly simplified transport equations, ignoring atomistic details and correlation between ion motion. In this work, we demonstrate an atomistic model of the discharge process of batteries that accounts for electric forces, forces because of chemical potential gradients, and compressive forces on all species, and relates them to the resulting molecular flux of the cations. The model unifies results from three different sets of simulations: 1) battery discharge simulation, which generates the flux of cations and resulting electrochemical potential gradients, 2) simulations measuring the effects of chemical potential gradients along with cross-terms, 3) non-equilibrium simulations measuring the correlation between applied forces on species and resulting molecular flux. This model self-consistently describes all the physical processes in the battery electrolyte and models the electrochemical oxidation and reduction of cations at the electrode surface as a first-order reaction driven by current density.