Electrochemical reduction of silicon chloride in a non-aqueous solvent

Nishimura, Yusaku; Fukunaka, Yasuhiro

doi:10.1016/j.electacta.2007.06.026

Cited by 93 publications

(84 citation statements)

References 22 publications

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“…In such Si electrodeposition processes, non-aqueous solvents are used as electrolytes because the reduction potential of Si is very negative and almost all Si precursors can easily react with water. Among the non-aqueous solvents, there have been several studies of organic solvents [1][2][3] and ionic liquids [4][5][6] because they can be used at low temperatures. Our earlier work has been on the deposition of Si from a SiCl 4 precursor, in particular, focusing on ionic liquids as the solvent and have reported the deposition of films and patterned structures.…”

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confidence: 99%

Analysis of Cathodic Reaction Process of SiCl₄during Si Electrodeposition in Ionic Liquids

Tsuyuki

Fujimura

Kunimoto

et al. 2017

J. Electrochem. Soc.

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Elementary steps in the electrochemical reduction process of SiCl 4 in trimethyl-n-hexylammonium bis(trifluoromethylsulfonyl) imide (TMHATFSI) was investigated, focusing on molecular level behavior of the reactants at solid-liquid interface. Electrochemical measurements using an electrochemical quartz crystal microbalance (EQCM) identified a reduction peak corresponding to Si electrodeposition and several elementary steps with stable intermediates forming prior to the deposition. For detailed analysis, X-ray reflectivity (XRR) measurements with synchrotron radiation were applied in situ. The change in reflectivity of the electrode surface during the deposition was found to be due to the formation of a polymer-like Si such as Si 2 Cl 6 , which is an intermediate layer during the deposition process. These results were theoretically supported by density functional theory (DFT) calculations: after an electron transfers from the electrode, the Si in SiCl 4 forms the bond with another SiCl 4 , rather than the Si of the substrate, resulting in the formation of the intermediate structure. These data suggest an elementary step in the SiCl 4 reduction process which can be described as follows; when SiCl 4 is reduced, a polymer-like Si form such as Si 2 Cl 6 is generated. This intermediate species further reacts with other Si reactants after receiving additional electrons, which then finally deposits as Si on the substrate.

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confidence: 99%

Analysis of Cathodic Reaction Process of SiCl₄during Si Electrodeposition in Ionic Liquids

Tsuyuki

Fujimura

Kunimoto

et al. 2017

J. Electrochem. Soc.

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“…12 This low silicon deposition efficiency has been correlated in the literature with electrolyte decomposition and side reactions related to the reactivity of SiCl 4 . 13,14 When the loading levels are calculated via weight difference of the bare copper foam and electrodeposited foam using conventional balance, the values obtained are ∼%50 (by weight) higher in comparison to active silicon mass calculations via electrochemistry. This can be explained by the presence of decomposition and side reaction products and residual solvent trapped in foam structure.…”

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confidence: 99%

Effect of Surface Termination on Electrochemical Performance of Silicon Thin Films

Doğan

Vaughey

2015

J. Electrochem. Soc.

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The surface termination layer of silicon-based lithium-ion anodes is a complex mixture of silicon oxides, hydroxides, and hydrides. The species present reflect the history of the electrode and combine to make each silicon electrode different in its electrochemical performance and reactivity with the electrolyte. This variability creates challenges for silicon-based anodes as it affects SEI formation and stability, columbic efficiency, and irreversible capacity. To elucidate some of the parameters that control surface functionality we used non-aqueous electrodeposition to produce silicon thin films on copper foams. These porous electrodes were studied using 29 Si MAS NMR to correlate the synthetic process and surface functionality with electrochemical performance. We found that the supporting electrolyte salt used has a significant effect on the electrodeposited silicon thin films electrochemical properties. Films deposited using tetrabutylammonium chloride (TBACl) were found to be more crystalline with much higher surface concentration of hydrides, hydroxides and oxides, have lower capacity, and much higher irreversible capacity than films deposited using tetraethylammonium chloride (TEACl). The role of supporting electrolyte salt is hypothesized to be related to the amount of free solvent in the reaction mixture as the TBACl salt has been reported to tie up significantly more solvent due its larger size. For many new LIB applications, the space available for the energy storage component in the end device is at a premium. This need is driving the search for new couples that can be designed, modified, or optimized to meet these volumetric goals. Among the materials under study, silicon is a promising alternative anode material to replace graphitic carbon in Li-ion batteries. Its attributes, including high specific capacity, both gravimetric (>3500 mAh/g) and volumetric (>2194 mAh/cm 3 ), and a low charge/discharge insertion/de-insertion voltage at room temperature make it desirable for many applications, however its large volume expansion (>300%) on cycling, poor capacity retention, and Coulombic inefficiencies have limited its use to date. 1,2 While many possible solutions have been proposed, including electrode surface modification, silicon dilution via creation of a composite anode, e.g. (Si-C), identifying new binders that control the expansion, or new electrode designs that contain the expansion, none alone have met the challenge. 3,4 While several studies have focused on the properties of silicon, its morphology, or its fabrication into an electrode, aspects of its electrochemical cycling, such as Coulombic inefficiencies, are related in part to the system level problem of how the silicon interface interacts with the electrolyte. Edström et al., utilizing Soft X-Ray Photoelectron Spectroscopy, was able to not only track SEI and surface changes within an electrochemical cell but was able to differentiate interfacial reaction products forming on the surface of underlying electrode materials.5 Philippe et al.,...

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“…Hence, it is expected to enable mass production with high productivity. These are the reasons why we have been engaged in electrochemical processing of Si (1)(2)(3)(4)(5)(6).…”

Section: Introductionmentioning

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<i>In Situ</i> Raman Spectroscopy Studies of the Electrolyte-Substrate Interface during Electrodeposition of Silicon in a Room-Temperature Ionic Liquid

et al. 2009

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The electrochemical reduction of SiCl 4 to Si in a hydrophobic room-temperature ionic liquid, trimethyl-n-hexylammonium bis(trifluoromethylsulfonyl)imide was in situ investigated by Raman spectroscopy. It revealed that SiCl 4 is electrochemically reduced to form amorphous Si (a-Si) and also silicon chloride species with Si-Si bonds as represented by Si m Cl n (n/m < 4). The amount of the formed a-Si increased with the progress of electrolysis. In addition, it seems that there is an incubation period before a-Si is intensively produced, in which Si m Cl n are generated. This information implies that a-Si may be generated by further reduction of Si m Cl n to form larger Si networks or by disproportionation reactions of Si m Cl n .

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Electrochemical reduction of silicon chloride in a non-aqueous solvent

Cited by 93 publications

References 22 publications

Analysis of Cathodic Reaction Process of SiCl₄during Si Electrodeposition in Ionic Liquids

Analysis of Cathodic Reaction Process of SiCl₄during Si Electrodeposition in Ionic Liquids

Effect of Surface Termination on Electrochemical Performance of Silicon Thin Films

<i>In Situ</i> Raman Spectroscopy Studies of the Electrolyte-Substrate Interface during Electrodeposition of Silicon in a Room-Temperature Ionic Liquid

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Electrochemical reduction of silicon chloride in a non-aqueous solvent

Cited by 93 publications

References 22 publications

Analysis of Cathodic Reaction Process of SiCl4during Si Electrodeposition in Ionic Liquids

Analysis of Cathodic Reaction Process of SiCl4during Si Electrodeposition in Ionic Liquids

Effect of Surface Termination on Electrochemical Performance of Silicon Thin Films

<i>In Situ</i> Raman Spectroscopy Studies of the Electrolyte-Substrate Interface during Electrodeposition of Silicon in a Room-Temperature Ionic Liquid

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Analysis of Cathodic Reaction Process of SiCl₄during Si Electrodeposition in Ionic Liquids

Analysis of Cathodic Reaction Process of SiCl₄during Si Electrodeposition in Ionic Liquids