Unveiling the First Nucleation and Growth Steps of Inorganic Solid Electrolyte Interphase Components

Abstract

The complexity of the solid electrolyte interphase (SEI) in lithium-ion batteries with graphitic electrodes has triggered extensive research efforts because of its crucial role on the lifetime of the battery. The SEI layer is composed of organic and inorganic species, resultant from the electrolyte decomposition at the electrode–electrolyte interface upon the first cycles of the battery. A stable SEI layer is essential to maintain the chemical and mechanical stability of the electrode as well as the electrochemical stability of the electrolyte in order to prevent further irreversible capacity loss. This work uses computational crystal structure prediction genetic evolutionary algorithms to simulate the nucleation, growth, and aggregation of the inorganic products forming the SEI mosaic film. In depth investigation of the growth mechanisms of LiF and Li2CO3 starting from the first nucleation seeds is undertaken. The cluster-stacking and layer-by-layer SEI growth on the graphite surface as well as near-shore SEI layer cluster aggregation growth mode are shown to be strongly dependent on the electrode degree of lithiation and nature of surface termination groups. Comparison among the various growth modes suggests that the most likely scenario is a mixed mode: small clusters may be formed in near-shore locations and migrate toward the surface during cycling, while nucleation and growth at the surface may also exist. This mixed mode of growth is consistent with a heterogeneous “mosaic” SEI picture suggested in the literature.

Not All Fluorination Is the Same: Unique Effects of Fluorine Functionalization of Ethylene Carbonate for Tuning Solid-Electrolyte Interphase in Li Metal Batteries

“…Researchers in this field have made remarkable progress in describing electrolyte decompositions and SEI formations. Various experimental techniques have been applied to characterize the electrochemical and chemical responses of the SEI. ,,,− Using computational approaches with quantum chemistry accuracy, “watching the SEI form” has been investigated by ab initio molecular dynamics (AIMD) , and density functional theory (DFT). ,− DFT compared to AIMD simulates a smaller system, limited largely to structural relaxation and no dynamics. However, it has significantly higher computational efficiency, thus allowing exploring a much larger variety of electrochemical and chemical feature spaces that are not accessible in AIMD.…”

Synchrotron Near-Field Infrared Nanospectroscopy and Nanoimaging of Lithium Fluoride in Solid Electrolyte Interphases in Li-Ion Battery Anodes

“…96 Further computational results have also suggested that LiF clusters can form and then migrate to the surface and that this process depends on the surface termination of the electrode. 93 Cao et al also demonstrated with computation that existing LiF nuclei can result in accelerated PF 6…”

Equilibrium and Dynamical Characteristics of the Solvation Associated with the Li+/Li Redox Couple at the Ethylene Carbonate/Graphene Interface

“…Although the previous description looks conceptually simple, microscopic interpretations of several processes that would eventually lead to further improvements in cell performances still remain not fully understood. In addition to direct experimental efforts that are currently being undertaken to unveil such details, a series of recent quantum calculations and computer simulations with atomistic detail − have provided valuable predictive information about equilibrium, stability, and dynamical characteristics associated with the redox processes taking place in the cells.…”