Investigation of carbon-coated silicon oxide phase changes during charge/discharge by oxygen and lithium K-Edge X-ray absorption fine structure spectroscopy

Hirose, Takakazu; Morishita, Masao; Yoshitake, Hideya; Sakai, Tetsuo

doi:10.1016/j.ssc.2017.10.004

Cited by 4 publications

(2 citation statements)

References 15 publications

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“…The difficulty resides in the fact that Li2O chemical shift (near 3ppm, based on tin oxide reaction study [41]) is overlapping with lithium silicate Li4SiO4 and possible electrolyte reduction products. Li2O has been spotted by X-ray techniques (XAFS, XPS) [42,43]. However lithium carbonate that can be found in the SEI (resulting from carbonate electrolyte reduction during formation) has been shown to react very quickly to form Li2O under soft X-ray irradiation [44].…”

Section: Positivementioning

confidence: 99%

Practical implementation of Li doped SiO in high energy density 21700 cell

Reynier

Vincens

Leys

et al. 2020

Journal of Power Sources

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Section: Positivementioning

confidence: 99%

Practical implementation of Li doped SiO in high energy density 21700 cell

Reynier

Vincens

Leys

et al. 2020

Journal of Power Sources

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“…Specifically, we have reported that at potentials above 0.7 V vs Li/ Li+, SiO disproportionation occurs, which deteriorates the battery characteristics; however, the use of potentials below 0.7 V vs Li/Li + significantly delays the deterioration of the SiO bulk structure. [16][17][18] When SiO is used as the anode material, the battery capacity experiences a sudden drop over the course of the first 100 cycles. This phenomenon occurs even if the capacity of the battery is improved by replacing some of the carbon-coated SiO (SiO-C) with graphite, thereby reducing the benefit of the increased battery capacity.…”

mentioning

confidence: 99%

Comparison of the Structure and Phase Changes of Carbon-Coated SiO and Li-Doped Carbon-Coated SiO During Repeated Charge–Discharge Cycling

Hirose

Takahashi

Matsuno

et al. 2020

J. Electrochem. Soc.

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Carbon-coated SiO (SiO-C), which is a high-capacity anode material, experiences a significant capacity drop in the initial charge-discharge cycles. In contrast, Li-doped SiO-C (Li-SiO-C), which has been recently developed, exhibits a significantly smaller capacity drop. To explain this difference, we performed a detailed investigation of the structures and phase changes associated with the charge-discharge cycling of these materials by comparing their Si structures and electronic states obtained from solid-state magic-angle spinning nuclear magnetic resonance and Si K-edge X-ray absorption fine structure measurements. The results show that, in the case of SiO-C, the Li 4 SiO 4 generated during charge is partially decomposed during discharge in the initial charge-discharge cycles. These generation and decomposition behaviors are most intense during the first 20 cycles. We believe that this phenomenon is the cause of the increased irreversible capacity observed in the initial cycles of SiO-C. In addition, we confirmed that Li 2 SiO 3 , a component of Li-SiO-C, is relatively stable electrochemically, although some of it gradually converts into Li 4 SiO 4 during charge-discharge cycling. The presence of Li 2 SiO 3 at the outset implies that less Li 4 SiO 4 is generated during charging compared to SiO-C, which we believe explains the lack of a significant capacity drop in the initial cycles of Li-SiO-C.

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