Coupled mechanochemical theories for reacting systems with application to nanovoid nucleation and Li-ion batteries

dc.contributor.advisor Valery I. Levitas Attariani, Hamed
dc.contributor.department Aerospace Engineering 2018-08-11T18:16:09.000 2020-06-30T02:53:33Z 2020-06-30T02:53:33Z Wed Jan 01 00:00:00 UTC 2014 2015-07-30 2014-01-01
dc.description.abstract <p>Hollow nanoparticles (NPs) are produced by void nucleation and growth during chemical reactions. However, there is no proper understanding of nucleation and growth mechanisms, and their predictive modeling. Furthermore, models based on the Kirkendall effect predict the process time, which is larger by orders of magnitude than in the experiment. A continuum-mechanics approach for nucleation and growth of a nanovoid in reacting NPs based on the Kirkendall effect is developed, which quantitatively describes the experimental results for oxidation of copper NPs. The results show that the core is under compression (which eliminates fracture hypothesis) which promotes void nucleation by decreasing equilibrium concentration of vacancies at the void surface.</p> <p>Si is a promising anode material for Li-ion batteries, since it absorbs large amounts of Li. However, insertion of Li leads to 334 % of volumetric expansion, huge stresses, and fracture; it can be suppressed by utilizing nanoscale anode structures. Continuum approaches to stress relaxation in Li<sub>x</sub>Si, based on plasticity theory, are unrealistic, because the yield strength of Li<sub>x</sub>Si is much higher than the generated stresses. Here, we suggest that stress relaxation is due to anisotropic (tensorial) compositional straining that occurs during insertion-extraction at any deviatoric stresses. Developed theory describes known experimental and atomistic simulation data. The stress evolution is modeled for different nanostructures (thin film, solid, and hollow nanoparticle) during lithiation-delithiation.</p>
dc.format.mimetype application/pdf
dc.identifier archive/
dc.identifier.articleid 4993
dc.identifier.contextkey 6199712
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath etd/13986
dc.language.iso en
dc.source.bitstream archive/|||Fri Jan 14 20:05:17 UTC 2022
dc.subject.disciplines Engineering
dc.subject.disciplines Engineering Mechanics
dc.subject.disciplines Mechanics of Materials
dc.subject.keywords large strain
dc.subject.keywords Li-ion batteries
dc.subject.keywords mechanochemical
dc.subject.keywords nanoparticles
dc.subject.keywords nanovoid
dc.subject.keywords stress relaxation
dc.title Coupled mechanochemical theories for reacting systems with application to nanovoid nucleation and Li-ion batteries
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication 047b23ca-7bd7-4194-b084-c4181d33d95d dissertation Doctor of Philosophy
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