Chemo-Mechanical Model of SEI Growth on Silicon Electrode Particles

Abstract

Silicon anodes promise high energy densities of next-generation lithium-ion batteries, but suffer from shorter cycle life. The accelerated capacity fade stems from the repeated fracture and healing of the solid-electrolyte interphase (SEI) on the silicon surface. This interplay of chemical and mechanical effects in SEI on silicon electrodes causes a complex aging behavior. However, so far, no model mechanistically captures the interrelation between mechanical SEI deterioration and accelerated SEI growth. In this article, we present a thermodynamically consistent continuum model of an electrode particle surrounded by an SEI layer. The silicon particle model consistently couples chemical reactions, physical transport, and elastic deformation. The SEI model comprises elastic and plastic deformation, fracture, and growth. Capacity fade measurements on graphite anodesand in-situ mechanical SEI measurements on lithium thin films provide parametrization for our model. For the first time, we model the influence of cycling rate on the long-term mechanical SEI deterioration and regrowth. Our model predicts the experimentally observed transition in time dependence from square-root-of-time growth during battery storage to linear-in-time growth during continued cycling. Thereby our model unravels the mechanistic dependence of battery aging on operating conditions and supports the efforts to prolong the battery life of next-generation lithium-ion batteries.

15 pages, 13 figures

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• Identifying the Mechanism of Continued Growth of the Solid-Electrolyte Interphase
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• Electrochemical kinetics of SEI growth on carbon black, II: Modeling
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Cited by in corpus (7)

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• Silicon Nanowires as Anodes for Lithium-Ion Batteries: Full Cell Modeling
• Simulation of the Deformation for Cycling Chemo-Mechanically Coupled Battery Active Particles with Mechanical Constraints
• Modeling and Simulation of Chemo-Elasto-Plastically Coupled Battery Active Particles
• Electro-Chemo-Mechanical Model for Polymer Electrolytes
• Transition between growth of dense and porous films: Theory of dual-layer SEI