Formation of solid electrolyte interphase in Li-ion batteries: Insights from temperature-accelerated ReaxFF molecular dynamics

The solid electrolyte interphase (SEI) forms between anode and electrolyte in the lithium-ion battery (LIB) and is considered to be the main contributor to LIB degradation. To understand the degradation and SEI formation, we use reactive force-field (ReaxFF) molecular dynamics to gain atomic level insights into the key phenomena. We report the effect of different reaction temperatures on SEI formation on the lithium metal anode surface in contact with pure ethylene carbonate electrolyte. The temperature elevation is found to boost the SEI formation. To investigate the structural variations of SEI, we compare the quantitative variations of key species and perform analysis using the charge distribution and radial distribution function (RDF). Our work reveals that elevated temperature of up to 700 K is appropriate for acceleration of chemical reactions during SEI formation. The study provides insights into structural variations of the lithium metal electrode and SEI at the molecular level, demonstrating that temperature-accelerated reactive molecular dynamics is an efficient and effective tool for predicting the performance and degradation of the Li-ion batteries.