Ab initio Molecular Dynamics Simulations of Initial Stage of SEI Film Formation

Kevin Leung (Sandia National Labs)

Joanne Budzien (Department of Physics and Engineering, Frostburg State University)

Most working commercial lithium ion batteries rely on organic solvent-based electrolytes which decompose on the graphitic negative electrode surface at the negative voltages at which battery charging take place. Ethylene carbonate (EC)-containing solvents are unique in their ability to form a stable passivating solid electrolyte interphase, SEI, layer that stops further electron-induced solvent decomposition. Ab initio molecular dynamics (AIMD) calculations can elucidate this process of SEI formation. We note that failure to form a good SEI layer leads to battery problems such as early aging, degradation and failure of the Li-ion battery. High quality intermolecular potentials are required in order for molecular dynamics to provide high quality results; in this work the molecular dynamics surface potentials are provided by ab initio quantum mechanics calculations.