Structural Study of Electrochemically Lithiated Si(111) by using Soft X‐ray Emission Spectroscopy Combined with Scanning Electron Microscopy and through X‐ray Diffraction Measurements

Aoki, Nana; Omachi, Asami; Uosaki, Kohei; Kondo, Toshihiro

doi:10.1002/celc.201600030

Cited by 23 publications

(57 citation statements)

References 45 publications

(93 reference statements)

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“…Moreover, the energy position of the emission peak of a-Li 13 Si 4 is 0.55 eV higher in energy if compared with the one of a-Li 15 Si 4 . Therefore it is unlikely that a-Li 13 Si 4 gives noticable contribution to the XES of the second layer observed by Aoki et al 76 The analysis of the Si-L The analysis performed above clearly demonstrates that combination of the theoretical and experimental methods of the soft X-ray emission spectroscopy can be used as a powerful tool for the comprehensive analysis of the anode materials in LIBs.…”

Section: Resultsmentioning

confidence: 83%

“…Recently, the structure, composition and electronic state of electrochemically lithiated Si(111) have been studied by methods of soft X-ray spectroscopy (SXES) combined with the X-ray diffraction with synchrotron radiation. 76 It has been reported that three different In the present work we perform theoretical analysis of the mechanisms of formation of the soft X-ray Si-L 2,3 emission of crystalline and amorphous Li x Si alloys. On the base of comparison of results of our calculations with the available experimental data we demonstrate that methods of SXES can be used as a powerful tool for the comprehensive analysis of the electronic and structural properties of crystalline and amorphous Li x Si alloys in LIBs.…”

Section: Introductionmentioning

confidence: 99%

“…This observation indicates manifestation of the crystalline structure. Based on the analysis of the XRD patterns it was concluded that the first layer most likely consist of the crystalline c-Li 15 Si 4 phase 76. However, comparison of the experimental XES of the first layer reported by Aoki et al76 with the results of our theoretical calculations clearly demonstrates that the X-ray emission from the first layer can not be explained by the emission from the crystalline c-Li 15 Si 4 phase only because of the considerable difference in the width and shape of the main Si-L 2,3 band.…”

mentioning

confidence: 99%

“…Based on the analysis of the XRD patterns it was concluded that the first layer most likely consist of the crystalline c-Li 15 Si 4 phase 76. However, comparison of the experimental XES of the first layer reported by Aoki et al76 with the results of our theoretical calculations clearly demonstrates that the X-ray emission from the first layer can not be explained by the emission from the crystalline c-Li 15 Si 4 phase only because of the considerable difference in the width and shape of the main Si-L 2,3 band. As it was discussed above the c-Li 15 Si 4 structure contains only isolated Si atoms, resulting in formation of the narrow spectral line in Si-L 2,3 emission as shown in Figure4aby solid red line.One can notice that the shape of the experimental XES of the first layer in the vicinity of its maximum is flat, reflecting superposition of two peaks at ∼91.5 eV and ∼92.0 eV marked in Figure4aas A and B, respectively.…”

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confidence: 99%

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Lithiation Products of a Silicon Anode Based on Soft X-ray Emission Spectroscopy: A Theoretical Study

et al. 2018

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Due to its exceptional lithium storage capacity silicon is considered as a promising candidate for anode material in lithium-ion batteries (LIBs). In the present work we demonstrate that methods of the soft X-ray emission spectroscopy (SXES) can be used as a powerful tool for the comprehensive analysis of the electronic and structural properties of lithium silicides Li x Si forming in LIB's anode upon Si lithiation. On the basis of density functional theory (DFT) and molecular dynamics (MD) simulations it is shown that coordination of Si atoms in Li x Si decreases with increase in Li concentration both for the crystalline and amorphous phases. In amorphous a-Li x Si alloys Si tends to cluster forming Si-Si covalent bonds even at the high lithium concentration. It is demonstrated that the Si-L 2,3 emission bands of the crystalline and amorphous Li x Si alloys show different spectral dependencies reflecting the process of disintegration of Si-Si network into Si clusters and chains of the different sizes upon Si lithiation. The Si-L 2,3 emission band of Li x Si alloys become narrower and shifts towards higher energies with an increase in Li concentration. The shape of the emission band depends on the relative contribution of the X-ray radiation from the Si atoms having different coordination. This feature of the Si-L 2,3 spectra of Li x Si alloys can be used for the detailed analysis of the Si lithiation process and LIB's anode structure identification.

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Section: Resultsmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Lithiation Products of a Silicon Anode Based on Soft X-ray Emission Spectroscopy: A Theoretical Study

et al. 2018

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“…16 In region (B), i.e., (iv), a-Li 2.5 Si is lithiated further to c-Li 15 Si 4 and a-Li x Si (2.5<x<3.75). [16][17][18][19][20] An outermost c-Li 15 Si 4 layer is formed as observed by in-situ TEM, 17,18 soft X-ray photoelectron spectroscopy (SXES) 20 and XRD 19,20 and its formation results from the highest Li concentration and energetic stability. 18 In region (C), i.e., (v) and (vi), a-Li x Si (2.5<x<3.75) is delithiated to a-Li 2 Si, 16 and then in region (D), i.e., (vii) and (viii), c-Li 15 Si 4 is delithiated to a-Li 2 Si, [16][17][18][19] because of higher stability of c-Li 15 Si 4 than a-Li 15 Si 4 .…”

Section: Resultsmentioning

confidence: 97%

Improvement of Cyclability of Li-Ion Batteries Using C-Coated Si Nanopowder Electrode Fabricated from Si Swarf with Limitation of Delithiation Capacity

Kimura

Matsumoto

Nishihara

et al. 2017

J. Electrochem. Soc.

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We have fabricated Si nanopowder from Si swarf using the simple ball milling method, and applied to Li-ion battery electrodes. Limitation of the delithiation capacity after deep lithiation at 0.01 V is the most effective to achieve a constant high capacity for long cycles. The delithiation capacity keeps constant at 1500 mAh/g until the 290th cycle, and it slightly decreases to 1480 mAh/g at the 300th cycle. However, without limitation of the lithiation and delithiation capacities in the voltage range between 1.5 and 0.01 V, the delithiation capacity monotonically decreases with the cycle number, and it becomes 950 mAh/g at the 300th cycle. With limitation of the lithiation capacity at 1500 mAh/g after deep delithiation at 1.5 V, the delithiation capacity keeps 1470 mAh/g until the 137th cycle, and then decreases monotonically with the cycles to 860 mAh/g at the 300th cycle. With limitation of the delithiation capacity, the overvoltage estimated from the lithiation and delithiation curves is the lowest, and peeling-off of Si nanopowder from the Si electrode is suppressed because of limited size changes of Si nanopowder during lithiation and delithiation of Si nanopowder.

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Nucleation and Growth of Lithium–Silicon Alloy on Crystalline Silicon

2018

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Si is an attractive material for anodes in Li ion batteries because of high specific capacity. However, it undergoes significant volume change during electrochemical reactions, causing mechanical fractures and capacity decay, which is a serious bottleneck for commercialization. Despite several research attempts to understand the stress evolution in Si, the process remains unclear. A fundamental study of the initial formation of the Li–Si alloy is hence necessary for a better understanding of the stress evolution. In this study, the nucleation and growth of Li–Si alloys on various crystalline Si (c‐Si) surfaces during lithiation is observed by the authors. Distinct Li–Si alloys are formed with square pyramid, triangular pyramid, and circular bump shapes on the {100}, {111}, and {110} surfaces, respectively. These unique structures are caused by the preference for Li insertion on the c‐Si surface and are maintained even after further growth of the alloy at the outermost layer. The particular structures are assumed to cause a different degree of stress at the reaction front during lithiation. The authors expect that this fundamental study will contribute to an optimal design of the Si anode based on the better understanding of the type of stress present at each c‐Si.

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Structural Study of Electrochemically Lithiated Si(111) by using Soft X‐ray Emission Spectroscopy Combined with Scanning Electron Microscopy and through X‐ray Diffraction Measurements

Cited by 23 publications

References 45 publications

Lithiation Products of a Silicon Anode Based on Soft X-ray Emission Spectroscopy: A Theoretical Study

Lithiation Products of a Silicon Anode Based on Soft X-ray Emission Spectroscopy: A Theoretical Study

Improvement of Cyclability of Li-Ion Batteries Using C-Coated Si Nanopowder Electrode Fabricated from Si Swarf with Limitation of Delithiation Capacity

Nucleation and Growth of Lithium–Silicon Alloy on Crystalline Silicon

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