Perspective—Structure and Stability of the Solid Electrolyte Interphase on Silicon Anodes of Lithium-ion Batteries

Abstract

The solid electrolyte interphase (SEI) acts as a protection layer on the surface the anodes of lithium ion batteries to prevent further electrolyte decomposition. Understanding the fundamental properties of the SEI is essential to the development of high capacity silicon anodes. However, the detailed mechanism of the generation of the evolution of the SEI on the silicon anodes is not fully understood. This manuscript reviews our recent investigations of the SEI on silicon anodes. We have studied the fundamental formation mechanism of the SEI on silicon anodes, along with the evolution which occurs to the SEI upon cycling.

Physicochemical Heterogeneity in Silicon Anodes from Cycled Lithium-Ion Cells

“…Unlike graphite which relies on the intercalation of Li + ions between graphene sheets, the silicon particles react with lithium to form a range of lithiated silicide structures, which have capacities that are much higher than that of graphite. − The repeated lithiation/delithiation reactions cause the breaking/reformation of Si–Si bonds, leading to volumetric changes, fracturing, and morphological evolution in the Si particles during electrochemical cycling. , These phenomena drive performance degradation of the electrode matrix by mechanisms that include active material isolation and enhanced electrolyte decomposition. Approaches to improve electrode performance have included the use of novel silicon materials, binder formulations, electrolyte compositions, prelithiation strategies, and the adoption of diverse electrode and cell architectures. − …”

Strategy for enhanced performance of silicon nanoparticle anodes for lithium-ion batteries

“…7e Si 2p spectrum corresponded to the substance Li x SiO y , which was an important component of the SEI lm, indicating the presence of a dense SEI layer on the surface of the electrode, similar to a metal oxide coating, which improves the alloying reaction of silicon with lithium. 53 As can be seen from Fig. 7f Ti 2p spectra, there were no obvious peaks of elemental Ti on the surface of the Si/s-C@TiO 2 electrode aer cycling.…”

Insight into SEI Growth in Li-Ion Batteries using Molecular Dynamics and Accelerated Chemical Reactions

“…It is interesting to notice that at early stages the compounds LiF and Li 2 EDC are more abundant near the anode surface, consistent with the interpretation of experimental results. 48,65,66 It is also interesting to notice that at longer time scales, these complexes were distributed rather widely and diffusely over in the whole SEI film. The Li 2 EDC molecules formed via dimerization (mostly after 75 ns of simulation) are mainly located on the outer SEI, in concurrence with the idea that organic complexes lay farther away from the anode.…”