(318i) Atomistic Modeling Strategies for Solid Electrolyte Interphase Formation and Properties in Lithium Ion Batteries

Lithium ion batteries have driven a technological revolution in consumer electronics and power tools, while also inspiring the development of fully electric vehicles. However, there remains a divide between their theoretical and practical performance as gains in capacity, lifetime, and charge rate are demanded for the evolution of the technologies they power. Many of the practical hurdles lie at the interfaces between the electrodes and the liquid electrolyte, in particular, the dynamic nature of the anode-electrolyte interface plays a key role in the determination of battery performance. The in situ formation of an ionic conducting and electronically insulating layer known as the solid electrolyte interphase (SEI) on the anode is critical to robust battery performance, yet a deep fundamental understanding of the process by which it is formed remains elusive. Due to the size and time scales of the electrolyte-electrode interfacial phenomena, limited experimental approaches may provide the appropriate resolution. Computational methods, however, may be applied at spatial and temporal scales often unavailable in experiments. This work details a computational approach to studying the formation of the SEI using atomistic simulations at explicit electrode-electrolyte interphases. Through a multi-scale approach, we have explored the formation of the SEI at various stages including: the reorganization of the electrolyte at a charged graphite electrode surface prior to the first reduction reaction, the transport behavior of the reaction intermediates near the electrode prior to SEI formation, the accumulation of reaction products/intermediates, and the formation of a solid layer on the graphite surface. At each stage of the process, interplay between the electrode-electrolyte and electrolyte-electrolyte interactions dictates behaviors at the molecular level which determine the structure, and ultimately the properties of the SEI, and therefore the LIB. In this talk, we will present some of our recent findings including what we believe to be key descriptors in to predicting these behaviors at the various stages of SEI formation. This improved understanding will hopefully provide design principles for future investigation into forming a stable SEI.