Plasticity of lithiated silicon under chemo-mechanical loading
(2013) 3rd International Conference on Material Modelling — Location: Warsaw, Poland (8.September.2013)
Files
icmm-abstract_Brassart.pdf
Restricted Access - Adobe PDF
- 39.35 KB
Details
- Authors
- Abstract
- In the search for high-energy density materials for Li-ion batteries, silicon has emerged as a promising candidate anode material due to its ability to absorb a large number of Li atoms. How- ever, the lithiation of silicon is accompanied by huge volumetric expansion (up to 300%) and severe structural changes. Lithiation-induced stresses may cause mechanical degradation of the electrode, resulting in capacity fading after several cycles of lithiation and delithiation. Stresses also affect the kinetics of reaction and diffusion of lithium into the Si host. Understanding the com- plex relationship between mechanics and chemistry in electrode materials is crucial for designing batteries with improved cycle life and reliability. It is now well-recognized that the lithiation strain in silicon can be accomodated by plastic de- formation in electrodes of small feature size. Lithiation of silicon leads to dramatic changes in its mechanical properties, from a brittle material in its pure form to an amorphous material that can sustain large inelastic deformation in the lithiated form. In particular, silicon demonstrates remark- able softening when subject to a combined chemo-mechanical loading, as compared to mechanical loading alone. However, the micro-mechanisms inducing the macroscopically observed plastic deformations in amorphous silicon are not well understood. In this work we propose a continuum model that couples diffusion, chemical reaction and large, inelastic deformations within a consistent thermodynamic framework. The model introduces a coupling between mechanical and chemical driving forces which reproduces the observed chemo- mechanical softening. The model formulation and parameter identification is supported by ab-initio calculations, as well as experimental measurements on thin film electrodes. The model was implemented into a FE software, allowing us to predict the stress and electric potential in silicon electrodes subjected to cycles of lithiation and delithiation.
- Affiliations
Citations
Brassart, L., Zhao, K., & Suo, Z. (2013). Plasticity of lithiated silicon under chemo-mechanical loading. 3rd International Conference on Material Modelling, Warsaw, Poland. https://hdl.handle.net/2078.5/200689