- 著者
- Toshiyuki NOHIRA
- 出版者
- The Electrochemical Society of Japan
- 雑誌
- Electrochemistry (ISSN:13443542)
- 巻号頁・発行日
- pp.20-00098, (Released:2020-09-15)
- 参考文献数
- 82
- 被引用文献数
- 2
In this paper, the author describes several new electrochemical reactions in molten salts (MSs) and ionic liquids (ILs), which includes the development of new ILs, and their applications. First, the electrochemical reduction of solid SiO2 to Si in molten CaCl2 at 1123 K is mentioned. The author explains the mechanism how the insulating SiO2 is electrochemically reduced to silicon. A new production method of solar grade silicon (SOG-Si) is introduced as one of the promising applications of the electrochemical reduction of SiO2. The author also mentions another new production method of SOG-Si which utilizes a liquid Si–Zn cathode in molten CaCl2. Secondly, the author describes the electrodeposition of silicon and titanium from water-soluble KF–KCl MSs. Compact crystalline Si films are electrodeposited from molten KF–KCl–K2SiF6 at 923 K. When K2TiF6 and Ti are added in molten KF–KCl, Ti(III) ions are produced by the proportionation reaction between Ti(IV) and Ti(0), in which compact Ti films can be electrodeposited. Thirdly, the author describes the binary and ternary mixtures of M[TFSA] (M = Li, Na, K, Rb, and Cs; TFSA = bis(trifluoromethylsulfonyl)amide) ILs as a new class of electrolytes for Li-ion batteries (LIBs) and Na-ion batteries (NIBs) operating in the intermediate temperature range. Fourthly, the development of binary and ternary mixtures of M[FSA] (M = Li, Na, K, Rb, and Cs; FSA = bis(fluorosulfonyl)amide) ILs and their applications for NIBs are mentioned; the binary and ternary mixtures of M[FSA] are unique in the points that they are inorganic compounds and have low melting temperatures. Finally, the author explains the development of several binary mixtures of M[FSA]–[Ocat][FSA] (M = Li, Na, and K; Ocat = organic cations) ILs which can be used for LIBs, NIBs, and KIBs (K-ion batteries). As a typical application of the M[FSA]–[Ocat][FSA] ILs, the development of practical NIB with a capacity of 27 Ah is described.
- 著者
- Tetsuya TOBA Kouji YASUDA Toshiyuki NOHIRA Xiao YANG Rika HAGIWARA Koki ICHITSUBO Kenta MASUDA Takayuki HOMMA
- 出版者
- The Electrochemical Society of Japan
- 雑誌
- Electrochemistry (ISSN:13443542)
- 巻号頁・発行日
- vol.81, no.7, pp.559-565, 2013-07-05 (Released:2013-07-05)
- 参考文献数
- 56
- 被引用文献数
- 19 31
Direct electrolytic reduction of SiO2 was investigated in molten CaCl2 at 1123 K as a fundamental study to develop a continuous process for solar-grade Si production. Several different types of SiO2 granules, as well as SiO2 pellets, were successfully reduced to Si on the bottom cathode of a Si plate. Three parameters were varied in the reduction of SiO2 granules: electrode potential, layer thickness of the SiO2 granules, and SiO2 particle size. The reduction rate was evaluated by the magnitude of the reduction current. The main factor determining the reduction rate was the diffusion of O2− ions inside the reduced porous Si layer filled with the electrolyte. Another factor which influenced the reduction rate was the contact resistance between Si granules.
- 著者
- Yutaro NORIKAWA Kouji YASUDA Toshiyuki NOHIRA
- 出版者
- The Electrochemical Society of Japan
- 雑誌
- Electrochemistry (ISSN:13443542)
- 巻号頁・発行日
- vol.86, no.2, pp.99-103, 2018-04-05 (Released:2018-04-05)
- 参考文献数
- 31
- 被引用文献数
- 13
The electrochemical behavior of Ti(III) ions in a eutectic KF–KCl molten salt was investigated using cyclic voltammetry, square wave voltammetry, and chronoamperometry at 923 K. Ti(III) ions were produced by the addition of 0.50 mol% of K2TiF6 and 0.33 mol% of Ti sponge to the melt. The reduction of Ti(III) ions to metallic Ti was observed as a single 3-electron wave around 0.33 V vs. K+/K in the square-wave voltammogram. The electrodeposition was conducted at a Mo electrode by galvanostatic electrolysis at −50 mA cm−2 for 20 min. The deposits were confirmed to be compact and adherent Ti metal films by scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction analysis. The oxidation of Ti(III) to Ti(IV) was observed at 1.82 V vs. K+/K as a reversible electrochemical process. The diffusion coefficient of Ti(III) ions was determined to be 3.9 × 10−5 cm2 s−1.