Electrochemical production of silicon

Yasuda, Kouji

doi:10.1515/htmp-2022-0033

Cited by 16 publications

(15 citation statements)

References 215 publications

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“…[105,111,113,138] However, electrodeposition of silicon at different electrode surfaces at room temperature is in the focus of research, and already covered by comprehensive reviews. [31][32][33][34]…”

Section: Sià Si Bond Formationmentioning

confidence: 99%

“…[20] While the field of electrochemical synthesis of organosilanes and silane compounds is constantly expanding and new, exciting concepts are being published, to our knowledge, no review has appeared since 2000 on the holistic view of synthesis routes starting from hydro-and halosilanes. [21][22][23][24][25][26] Whereas there are reviews regarding the electrochemical synthesis of organosilicon species, [2,[21][22][23][24][25][26][27][28] formation of polysilanes, [29,30] the electro-deposition of silicon starting from halosilanes, [31][32][33][34] and silyl radical driven conversions, [35] this review is focused on the electrochemical Si bond formation starting from chloro-and hydrosilanes. Ionic as well as the radical related type of conversion are the scope of the present analysis, further providing a general view on common obstacles regarding the work with chloro-and hydrosilanes.…”

Section: Introductionmentioning

confidence: 99%

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General Concepts and Recent Advances in the Electrochemical Transformation of Chloro‐ and Hydrosilanes

2023

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Organosilanes play an important role in organic synthesis as well as in a variety of further areas, ranging from life science to transportation. Especially, the electrochemical access has become increasingly important in the past years and developed into an essential topic due to new conceptual approaches and mediated reaction control. With the commercial availability of high‐quality electrochemical equipment, the technical requirements for electro‐conversion are at hand to a wide audience. This results in the need for a concise survey of electrochemical silane transformation, appropriate for novices as well as experts alike. This review provides an overview of the most relevant work in this field, identifies common obstacles in working with chlorosilanes and hydrosilanes and bridges the gap between known techniques and novel methods with respect to their electrochemical conversion. The historical development is outlined with reference to the various cathodic as well as anodic conversions and should encourage to expand the research field of electrochemical silane transformation.

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Section: Sià Si Bond Formationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

General Concepts and Recent Advances in the Electrochemical Transformation of Chloro‐ and Hydrosilanes

2023

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“…However, conventional Si substrate manufacturing methods have major drawbacks, such as low productivity with the Siemens method and a large kerf loss with the Si slice method. With the increasing demand for crystalline Si solar cells, there is a strong need to develop alternative manufacturing methods for Si substrates. , A promising method is the direct formation of Si films on inexpensive substrates. We investigated the electrodeposition of Si using a KF–KCl molten salt.…”

Section: Electrodeposition Of Siliconmentioning

confidence: 99%

A New Concept of Molten Salt Systems for the Electrodeposition of Si, Ti, and W

Norikawa

2023

Acc. Chem. Res.

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Conspectus This Account describes the results of the electrodeposition of film-like Si, Ti, and W by utilizing molten salts selected based on a new concept. The proposed molten salt systems, KF–KCl and CsF–CsCl, have high fluoride ion concentrations, relatively low operating temperatures, and high solubility in water. First, KF–KCl molten salt was used for the electrodeposition of crystalline Si films to establish a new fabrication method for Si solar cell substrates. The electrodeposition of Si films from the molten salt at 923 and 1023 K was successfully achieved using K2SiF6 or SiCl4 as the Si ion source. The crystal grain size of Si was larger at higher temperatures, indicating that higher temperatures are advantageous for the application of Si solar cell substrates. The resulting Si films underwent photoelectrochemical reactions. Second, the electrodeposition of Ti films using the KF–KCl molten salt was investigated to easily impart the properties of Ti, such as high corrosion resistance and biocompatibility, to various substrates. Ti films with a smooth surface were obtained from the molten salt containing Ti(III) ions at 923 K. Electrochemical tests in artificial seawater revealed that the electrodeposited Ti films had no voids and cracks and that the obtained Ti-coated Ni plate had a high corrosion resistance against seawater. Finally, the molten salts were used for the electrodeposition of W films, which are expected to be used as diverter materials for nuclear fusion. Although the electrodeposition of W films was successful in the KF–KCl–WO3 molten salt at 923 K, the surface of the films was rough. Therefore, we used the CsF–CsCl–WO3 molten salt, which can be employed at lower temperatures than KF–KCl–WO3. We then successfully electrodeposited W films with a mirror-like surface at 773 K. Such a mirror-like metal film deposition has not been reported before using high-temperature molten salts. Further, the temperature dependence of the crystal phase of W was revealed by the electrodeposition of W films at 773–923 K. β-W was obtained at 773 and 823 K, α-W was obtained at 923 K, and a mixed phase of α- and β-W was obtained at 873 K. In addition, single-phase β-W films with a thickness of approximately 30 μm were electrodeposited, which has not been reported before. The results show that our proposed molten salt systems are advantageous for electroplating Si, Ti, and W. Our approach is also expected to be applicable for the electrodeposition of other metals such as Zr, Nb, Mo, Hf, and Ta.

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“…In the 1970s and 1980s, it has been reported that crystalline silicon was electrodeposited in the fluoride melts containing K 2 SiF 6 . − Electrodeposition of silicon from SiO 2 in chloride melts , and from SiCl 4 in chloride–fluoride melts was also investigated. Recently, the review of the silicon electrodeposition in high-temperature molten salt has been reported in some papers. , …”

Section: Introductionmentioning

confidence: 99%

“…Recently, the review of the silicon electrodeposition in high-temperature molten salt has been reported in some papers. 12,13 In the electrodeposition process of silicon in high-temperature molten salt, fluoride melt has advantages in that it is the medium for electrowinning of Si directly from SiO 2 because of the high solubility of its metal oxides at relatively lower temperatures. The authors have reported that silicon film can be obtained by electrochemical reduction of SiO 2 in LiF− NaF−KF at 873 K. 14,15 By using nonconsumable oxygenevolving materials such as boron-doped diamond 16 and conductive ceramics 17 for anodes and electrical power derived from renewable energy sources for supplying the electricity needed for heating molten salts and conducting electrolysis, it is possible to construct a silicon manufacturing process without carbon dioxide emissions.…”

Section: Introductionmentioning

confidence: 99%

Coordination Structure of Si(II) Ions in Binary Melts (LiF–KF, LiF–NaF, and NaF–KF) and Ternary Melt (LiF–NaF–KF)

Suzuki,

Nozaki,

Tanaka

et al. 2023

Inorg. Chem.

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The formation of Si(II) by the comproportionation reaction between electrodeposited silicon and Si(IV) ions [Si(IV) + Si 0 ⇄ 2Si(II)] in fluoride melts has been discussed in many previous reports on the electrochemical processing of silicon. In this study, the coordination structure of Si(II) ions in LiF−KF, LiF− NaF, NaF−KF, and LiF−NaF−KF melts was investigated by hightemperature Raman spectroscopy and quantum chemical calculation based on density functional theory. The formation of Si(II) ions was induced by mixing metallic silicon powder as the source of Si 0 , with the melts containing hexafluoro silicate or silicon dioxide as the source of Si(IV) ions. The simulated vibrational modes of the Si(II) species and the experimental Raman bands showed good agreement. It was found that both Si(II) and Si(IV) species were detected in either fluoride melt, demonstrating that the proposed comproportionation reaction between Si 0 and Si(IV) occurred. In addition, the interaction between Si(II) and F − , O 2− , Li + , Na + , and K + ions significantly changed depending on the composition of fluoride melts. The coordination structure of the Si(II) ions reported in this study will provide clues for controlling the electrodeposition process of silicon in fluoride melts.

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Electrochemical production of silicon

Cited by 16 publications

References 215 publications

General Concepts and Recent Advances in the Electrochemical Transformation of Chloro‐ and Hydrosilanes

General Concepts and Recent Advances in the Electrochemical Transformation of Chloro‐ and Hydrosilanes

A New Concept of Molten Salt Systems for the Electrodeposition of Si, Ti, and W

Coordination Structure of Si(II) Ions in Binary Melts (LiF–KF, LiF–NaF, and NaF–KF) and Ternary Melt (LiF–NaF–KF)

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