Influence of heterogeneity on delamination of the solid-electrolyte interphase from silicon anode particles of lithium-ion batteries

Abstract

A finite deformation framework is employed to investigate the possibility of delamination of the solid electrolyte interphase (SEI) layer from a hollow cylindrical silicon (Si) anode particle during lithiation, accounting for SEI heterogeneity and mechanical deformation. The model includes a bilayer heterogeneous SEI with pre-existing cracks, situated on the outer surface of a fixed and axially constrained Si cylinder. Diffusion-induced stresses are investigated, together with plastic deformation of the active material and the SEI. Parametric studies are performed by varying SEI thickness, active material thickness, SEI heterogeneity, the mechanical and geometric properties of the organic and inorganic SEI layers, and the number of cracks. The results reveal that the presence of SEI heterogeneity raises the critical state of charge (SOC) required for delamination, thereby enhancing mechanical resilience. Plastic deformation delays the onset of failure by facilitating stress relaxation within the anode. A comparison between one-way and two-way coupling cases highlights the importance of feedback mechanisms in accurately capturing interfacial failure. The proposed modeling approach offers insights into improved design of artificial SEI layers that is expected to contribute toward the development of lithium-ion batteries.