Self-generated concentration and modulus gradient coating design to protect Si nano-wire electrodes during lithiation

Sung Yup Kim, Alireza Ostadhossein, Adri C T Van Duin, Xingcheng Xiao, Huajian Gao, Yue Qi

Research output: Contribution to journalArticle

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Abstract

Surface coatings as artificial solid electrolyte interphases have been actively pursued as an effective way to improve the cycle efficiency of nanostructured Si electrodes for high energy density lithium ion batteries, where the mechanical stability of the surface coatings on Si is as critical as Si itself. However, the chemical composition and mechanical property change of coating materials during the lithiation and delithiation process imposed a grand challenge to design coating/Si nanostructure as an integrated electrode system. In our work, we first developed reactive force field (ReaxFF) parameters for Li-Si-Al-O materials to simulate the lithiation process of Si-core/Al2O3-shell and Si-core/SiO2-shell nanostructures. With reactive dynamics simulations, we were able to simultaneously track and correlate the lithiation rate, compositional change, mechanical property evolution, stress distributions, and fracture. A new mechanics model based on these varying properties was developed to determine how to stabilize the coating with a critical size ratio. Furthermore, we discovered that the self-accelerating Li diffusion in Al2O3 coating forms a well-defined Li concentration gradient, leading to an elastic modulus gradient, which effectively avoids local stress concentration and mitigates crack propagation. Based on these results, we propose a modulus gradient coating, softer outside, harder inside, as the most efficient coating to protect the Si electrode surface and improve its current efficiency.

LanguageEnglish (US)
Pages3706-3715
Number of pages10
JournalPhysical Chemistry Chemical Physics
Volume18
Issue number5
DOIs
StatePublished - Feb 7 2016

Profile

wire
Wire
coatings
Coatings
gradients
Electrodes
electrodes
Stress concentration
Nanostructures
mechanical properties
Mechanical properties
stress concentration
Mechanical stability
Solid electrolytes
solid electrolytes
crack propagation
field theory (physics)
stress distribution
electric batteries
Crack propagation

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Physics and Astronomy(all)

Cite this

Self-generated concentration and modulus gradient coating design to protect Si nano-wire electrodes during lithiation. / Kim, Sung Yup; Ostadhossein, Alireza; Van Duin, Adri C T; Xiao, Xingcheng; Gao, Huajian; Qi, Yue.

In: Physical Chemistry Chemical Physics, Vol. 18, No. 5, 07.02.2016, p. 3706-3715.

Research output: Contribution to journalArticle

Kim, Sung Yup ; Ostadhossein, Alireza ; Van Duin, Adri C T ; Xiao, Xingcheng ; Gao, Huajian ; Qi, Yue. / Self-generated concentration and modulus gradient coating design to protect Si nano-wire electrodes during lithiation. In: Physical Chemistry Chemical Physics. 2016 ; Vol. 18, No. 5. pp. 3706-3715
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