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: Research - peer-reviewArticle

    • 11 Citations

    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
    coatings
    gradients
    electrodes
    Wire
    Coatings
    Electrodes
    mechanical properties
    Stress concentration
    Nanostructures
    Mechanical properties
    stress concentration
    solid electrolytes
    crack propagation
    field theory (physics)
    stress distribution
    electric batteries
    modulus of elasticity
    chemical composition
    flux density

    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: Research - peer-reviewArticle

    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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