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Interfacial Reactions in the Li/Si diffusion couples: Origin of Anisotropic Lithiation of Crystalline Si in Li-Si batteries.

ABSTRACT: As opposed to the common understanding that diffusion into a cubic-structured single crystal is independent of its crystalline orientation, the diffusion of Li to crystalline Si (c-Si) is anisotropic, which acts as the major cause for the fracture of Si anodes in Li-ion batteries. Here, by conducting comprehensive/multi-scale simulation studies based on molecular dynamics and density functional theory, we elucidate how and why Li diffusion in c-Si is anisotropic. We found that Li ions diffuse to c-Si by following a particular atomic-scale space corresponding to the lowest value of the valence orbital in c-Si, causing Li ions to take a tortuous diffusion pathway. The degree of the tortuosity of the pathway differs depending on the crystallographic orientation of Si, and it acts as the major cause for anisotropic lithiation. We also develop a structural parameter that can quantitatively evaluate the orientation dependency of the lithiation of c-Si.

SUBMITTER: Choi YS

PROVIDER: S-EPMC5656666 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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Interfacial Reactions in the Li/Si diffusion couples: Origin of Anisotropic Lithiation of Crystalline Si in Li-Si batteries.

Choi Yong-Seok YS Park Jun-Hyoung JH Ahn Jae-Pyoung JP Lee Jae-Chul JC

Scientific reports 20171025 1

As opposed to the common understanding that diffusion into a cubic-structured single crystal is independent of its crystalline orientation, the diffusion of Li to crystalline Si (c-Si) is anisotropic, which acts as the major cause for the fracture of Si anodes in Li-ion batteries. Here, by conducting comprehensive/multi-scale simulation studies based on molecular dynamics and density functional theory, we elucidate how and why Li diffusion in c-Si is anisotropic. We found that Li ions diffuse to ...[more]

PMID: 29070873

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Project description:Silicon with the properties of high capacity capability, moderate working potential, environmental sensitivity, and existence are the highly promising anode materials for lithium-ion batteries. Silicon anodes have disadvantageous properties and advantages like 300% volume change during lithium insertion and extraction process that can result in capacity fading and a shorter lifetime of the battery. In the literature, different optimizations of Silicon with different nanomaterials or composite materials, in different ratios, and with different binders and different procedures have been studied. The physical mixing of silicon with carbon provides a good performance by combining the high lithium storage capacity of the silicon and the good mechanical and conductive properties of carbon. Binders are one of the other factors affecting the performance of the Si/C anodes. In this study, different ratios of silicon/graphite combinations were tested. The Si/C hybrid material provides an advantageous and efficient use for innovative lithium-ion anodes and available lithium-ion battery technology when the Si/C match performs a suitable combination of two material properties, such as the high lithium storage capacity of silicon and the conductive properties of carbon. This study is aimed to improve the performance of the cell by changing the amount of active material and polymer in the electrode by finding the most appropriate amount of active substance and binder polymer ratio in the electrode. The electrochemical result of the composition, which compensates for the problems caused by the volume expansion of the silicon by using less silicon, showed higher capacitive properties, as it exhibits better adhesion among these compositions with a higher binder ratio. This study resulted in more than 1000 mAh/g specific capacity after 100 cycles at C/3 rate and structural characterization of the samples before and after cycling provided information about the electrode content.

Dataset Information

Interfacial Reactions in the Li/Si diffusion couples: Origin of Anisotropic Lithiation of Crystalline Si in Li-Si batteries.

Publications

Interfacial Reactions in the Li/Si diffusion couples: Origin of Anisotropic Lithiation of Crystalline Si in Li-Si batteries.

Similar Datasets

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