High purity silicon materials prepared through wet-chemical and electrochemical approaches

Takayuki Homma, Nobufumi Matsuo, Xiao Yang, Kouji Yasuda, Yasuhiro Fukunaka, Toshiyuki Nohira

    Research output: Contribution to journalArticle

    9 Citations (Scopus)

    Abstract

    A new approach to produce high purity solar grade silicon (SOG-Si) using wet-chemical and electrochemical processes was proposed. First, diatomaceous earth was used as a source of silica and wet-chemical purification by acid leaching and solvent extraction processes were applied for eliminating heavy metal and light element such as boron, respectively. In particular, the solvent extraction using channel flow reactor demonstrated extremely high efficiency for eliminating boron to 7N (99.99999%) level purity. Secondly, the high-purity silica was reduced to silicon by the direct electrolysis method using molten CaCl2 as an electrolyte and Si plate as cathode. We proposed the continuous electrolysis system by feeding silica granules to the Si cathode set at the bottom of the cell. It was confirmed that the reduction proceeded steadily to form crystalline Si with a sufficient reduction rate. We also attempted electrodeposition of Si films and have developed a process using KF-KCl + K2SiF6 molten salt, from which uniform layer of Si with a thickness larger than 100 μm could be formed.

    Original languageEnglish
    Pages (from-to)512-518
    Number of pages7
    JournalElectrochimica Acta
    Volume179
    DOIs
    Publication statusPublished - 2015 Oct 10

    Fingerprint

    Silicon
    Silicon Dioxide
    Boron
    Silica
    Solvent extraction
    Electrolysis
    Molten materials
    Cathodes
    Diatomaceous Earth
    Channel flow
    Heavy Metals
    Electrodeposition
    Electrolytes
    Leaching
    Heavy metals
    Purification
    Salts
    Earth (planet)
    Crystalline materials
    Acids

    ASJC Scopus subject areas

    • Electrochemistry
    • Chemical Engineering(all)

    Cite this

    High purity silicon materials prepared through wet-chemical and electrochemical approaches. / Homma, Takayuki; Matsuo, Nobufumi; Yang, Xiao; Yasuda, Kouji; Fukunaka, Yasuhiro; Nohira, Toshiyuki.

    In: Electrochimica Acta, Vol. 179, 10.10.2015, p. 512-518.

    Research output: Contribution to journalArticle

    Homma, Takayuki ; Matsuo, Nobufumi ; Yang, Xiao ; Yasuda, Kouji ; Fukunaka, Yasuhiro ; Nohira, Toshiyuki. / High purity silicon materials prepared through wet-chemical and electrochemical approaches. In: Electrochimica Acta. 2015 ; Vol. 179. pp. 512-518.
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    AU - Nohira, Toshiyuki

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