期刊
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
卷 69, 期 -, 页码 84-111出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmps.2014.04.012
关键词
Lithium-ion battery; Diffusion; Large deformation; Anisotropic strain; Silicon
资金
- NSF [CMMI-0969143]
- ONR [N00014-12-1-0525]
- Iowa State University
A general large-strain thermodynamic approach with anisotropic (tensorial) compositional expansion/contraction in elastoplastic material under stress tensor is developed. The dissipation rate due to compositional expansion/contraction is introduced. Adapting and utilizing a previously formulated postulate of realizability, we derived a simple equation for the deviatoric part of the compositional deformation rate. This leads to a nontrivial generalization of the concept and expression for the chemical potential. It receives a contribution from deviatoric stresses, which leads to an increase in the driving force for both the compositional expansion and contraction and to some new phenomena. Our model provides a remarkable description of the known experimental and atomistic simulation data on the biaxial stress evolution during lithiation-delithiation of LixSi on a rigid substrate with just one constant kinetic coefficient. In contrast to known approaches, it does not involve plasticity, because the yield strength is higher than the stresses generated during lithiation-delithiation. This allowed us to suggest a method for reduction in internal stresses by cyclic change in Li concentration with a small amplitude, and our simulations were in qualitative agreement with known experiments. The coupled diffusion and mechanical model was applied to lithiation and delithiation of thin-film, solid, and hollow spherical nanoparticles. The importance of the contribution of the deviatoric stress on the diffusion is demonstrated. (C) 2014 Elsevier Ltd. All rights reserved.
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