Applications of Ab Initio Molecular Dynamics for Modeling Batteries

Classical molecular dynamics (MD) has often been used to study the properties of electrolytes in battery systems owing to the large system sizes and long time scales that are possible; however, classical MD suffers from several drawbacks, such as the fact that (1) empirical and often non-transferable force fields are needed and (2) electron transfer and bond breaking and formation are not possible to model. Recently, a combination of density functional theory and MD, known as ab initio molecular dynamics (AIMD) has been gaining prominence as a way to circumvent these issues. In addition to providing key insights into time-dependent phenomena in batteries, AIMD has also been used to design new electrolytes, model chemical reactions related to degradation, and better understand battery components from an atomistic viewpoint. In this chapter we highlight recent advances in these applications of AIMD, including (1) the use of AIMD for generating solid and solvation structures, and evaluating their stability, (2) studying diffusion in cathode and anode materials as well as through electrolytes (both liquid and solid), (3) calculating voltage for batteries in which the electrolyte plays an energetic role in the charge/discharge process, and (4) modeling interfacial electrolyte breakdown and solid-electrolyte interphase formation.