Abstract
This study investigated the ionic species and electrochemical reduction of silicate ions at a solid graphite electrode in molten NaCl–CaCl2 eutectic melts with various concentrations of O2− ion at 1023 K. Silicate ion species in the melts with various O2−/SiO2 ratios (
r
O
2
−
/
SiO
2
)
were determined by Raman spectroscopy. The dominant species was SiO3
2− for
r
O
2
−
/
SiO
2
= 1.0, and SiO4
4− for
r
O
2
−
/
SiO
2
= 1.5 and 2.0. From cyclic voltammetry, XRD, and SEM analyses, electrochemical reduction was indicated for SiO3
2− and SiO4
4− at more negative than 1.0 V and 0.80 V vs Na+/Na, respectively. Formation of CaSi2 was confirmed at 0.50 V in all molten salts with
r
O
2
−
/
SiO
2
= 1.0, 1.5, and 2.0. The potential ranges for pure Si deposition are almost the same in molten salts with
r
O
2
−
/
SiO
2
= 1.0 and 1.5.
Funder
Japan Society for the Promotion of Science
Institute of Advanced Energy, Kyoto University
Publisher
The Electrochemical Society
Subject
Materials Chemistry,Electrochemistry,Surfaces, Coatings and Films,Condensed Matter Physics,Renewable Energy, Sustainability and the Environment,Electronic, Optical and Magnetic Materials
Cited by
11 articles.
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