Two-phase versus two-stage versus multi-phase lithiation kinetics in silicon

Cui, Zhiwei; Gao, Feng; Qu, Jianmin

doi:10.1063/1.4824064

Cited by 12 publications

(6 citation statements)

References 18 publications

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“…Without considering these aspects, it will not qualitatively change the conclusion though. More complicated models that couple finite deformation kinematics, stress–diffusion interaction, and chemical reaction also point out that, for a given ratio between the rate of interfacial reaction and that of Li diffusion in Si, a higher charging rate is likely to cause a two-phase process, while lower rates may result in continuous phase lithiation, , which in our case is in fact called single-phase lithiation.…”

Section: Resultsmentioning

confidence: 95%

Quantifying Electrochemical Reactions and Properties of Amorphous Silicon in a Conventional Lithium-Ion Battery Configuration

Wang

Singh

et al. 2017

Chem. Mater.

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Despite many existing studies on silicon (Si) anodes for lithium ion batteries (LIBs), many essential questions still exist on compound formation, composition, and properties. Here we show that some previously accepted findings may have limitations in reflecting the lithiation mechanisms in the conventional charging rate. Furthermore, the correlation between structure and mechanical properties in these materials has not been properly established. Here we report a rigorous and thorough study to comprehensively understand the electrochemical reaction mechanisms of amorphous-Si (a-Si) in a conventional charging rate. In-depth microstructural characterization was performed, and correlations were established between Li–Si composition, volumetric expansion, and modulus/hardness. We have found that the lithiation process of a-Si at a conventional charging rate is a single-phase reaction while it is a two-phase reaction at high rate in in situ TEM experiments. The findings in this paper establish a reference to quantitatively explain many key metrics for lithiated a-Si as anodes in real LIBs and can be used to rationally design a-Si based high-performance LIBs guided by high-fidelity modeling and simulations.

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Section: Resultsmentioning

confidence: 95%

Quantifying Electrochemical Reactions and Properties of Amorphous Silicon in a Conventional Lithium-Ion Battery Configuration

Wang

Singh

et al. 2017

Chem. Mater.

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“…Differentiation of equation (31) with respect to time with the help of equations ( 16), ( 24), (28) implies that…”

Section: Derivation Of Constitutive Equationsmentioning

confidence: 99%

“…It should be noted that equation (63) differs from the conventional extension of strain energy density for a linear elastic medium to finite strains [19,27,31].…”

Section: Materials Functionsmentioning

confidence: 99%

“…A constitutive framework for the description of volume expansion and diffusion-induced plastic flow in a host medium (treated as an one-phase continuum) at finite strains was developed in [17][18][19][20][21]. Distribution of stresses under lithiation of electrode particles modeled as twophase media was analyzed in [22][23][24][25][26] at small strains and in [28][29][30][31][32] in the framework of finite deformations.…”

Section: Introductionmentioning

confidence: 99%

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Development of stresses in silicon nanolayer under lithiation

Drozdov¹,

Sommer‐Larsen²

2014

Modelling Simul. Mater. Sci. Eng.

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Constitutive equations are developed for the mechanical response of a host medium driven by diffusion of guest atoms under an arbitrary three-dimensional deformation with finite strains. The model distinguishes two states of a guest atom: mobile and immobilized (due to alloying of host and guest atoms). Derivation of reaction–diffusion equations for transport and immobilization of guest atoms, as well as stress–strain relations for the viscoplastic behavior of the host material, is grounded on the free-energy imbalance inequality. The governing equations are applied to the analysis of stresses in an amorphous silicon nanolayer under lithiation. Good agreement is revealed between results of numerical simulation and observations on evolution of thicknesses of lithiated and non-lithiated domains and volume growth of the lithiated layer.

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“…For instance, biaxial stress occurs in the lithiated Si thin films, owing to the substrate constraints. − Such biaxial stress in a -Li x Si is lower than the intrinsic yield stresses of a -Li x Si, owing to the reaction-assisted plastic flow in a -Li x Si. , As in Si particles with only one-phases states, computational studies demonstrate that lithiation leads to the tensile radial stress, while the compressive-to-tensile hoop stress transitions from the outer to inner parts of Si particles. , The compressive surface stress reduces the Li diffusivity and blocks the lithiation process. , Second, the competition between reaction kinetics and Li diffusion rates determines the lithiation process and subsequent stress states in Si anodes. If the reaction kinetics is much slower than the Li diffusion rate, the lithiation of Si particles occurs in a two-phase way, , in which the inner pure Si phase is separated from the outer fully lithiated phase by a sharp phase interface. − In such case, both radial and hoop stresses are compressive in the inner Si phases, compared with the tensile ones in the outer lithiated phase. , The tensile surface stress may fracture the outer shell; meanwhile, the compressive one at the phase interface can highly increase the energy barrier for lithiation kinetics. − Finally, battery operating conditions may mechanically degrade Si anodes. The high charging/discharging rates produce the inhomogeneous distribution of Li concentrations and thus the stress concentration in Si anodes. , …”

Section: Introductionmentioning

confidence: 99%

Stress-Dependent Chemo-Mechanical Performance of Amorphous Si Anodes for Li-Ion Batteries upon Lithiation

Wang

Zhai

et al. 2021

ACS Appl. Energy Mater.

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Alloying-type anodes are significantly governed by their chemo-mechanical performance during the electrochemical cycling. The reaction-induced huge volumetric change of these anodes may cause material degradation and failure under mechanical constraints. Here, we investigate the stress-dependent lithiation behavior of amorphous Si (a-Si) anodes using molecular dynamics simulations. It is indicated that a-Si anodes can sustain higher hydrostatic stress than biaxial/uniaxial ones without the occurrence of mechanical failure. Thermodynamic and electrochemical calculations demonstrate that although the lithiation procedure also affects the thermodynamic stability of a-Si anodes, it is mainly dominated by the external mean stresses. Compressive stress is confirmed to destabilize a-Si anodes and further trigger their capacity fading. Compared with our atomistic simulations, previous continuum models underestimate the open-cell potentials of a-Si anodes, due to their ignored large volumetric deformation at higher stresses and Li concentrations. This computational study provides the intensive atomic-level understanding of the stress-dependent lithiation behavior of a-Si anodes.

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Two-phase versus two-stage versus multi-phase lithiation kinetics in silicon

Cited by 12 publications

References 18 publications

Quantifying Electrochemical Reactions and Properties of Amorphous Silicon in a Conventional Lithium-Ion Battery Configuration

Quantifying Electrochemical Reactions and Properties of Amorphous Silicon in a Conventional Lithium-Ion Battery Configuration

Development of stresses in silicon nanolayer under lithiation

Stress-Dependent Chemo-Mechanical Performance of Amorphous Si Anodes for Li-Ion Batteries upon Lithiation

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