2022-Sustainable Industrial Processing Summit
SIPS2022 Volume 4 Kipouros Intl. Symp. Molten Salt, Ionic & Glass-forming Liquids & Powdered Materials
| Editors: | F. Kongoli, R. Fehrmann, V. Papangelakis, I.Paspaliaris, G. Saevarsdottir. |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2022 |
| Pages: | 100 pages |
| ISBN: | 978-1-989820-40-7(CD) |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Electrochemical Reduction of Lithium Carbonate in Chloride Melts in Different Gaseous Media
Inessa Novoselova1; Sergei Kuleshov2; Anatoliy Omel'chuk3;1V.I. VERNADSKII INSTITUTE OF GENERAL AND INORGANIC CHEMISTRY, NATIONAL ACADEMY OF SCIENCES OF UKRAINE, Kyiv, Ukraine; 2INSTITUTE OF GENERAL AND INORGANIC CHEMISTRY, Kiev, Ukraine; 3UKRAINIAN NATIONAL ACADEMY OF SCIENCES V.I.VERNADSKY INSTITUTE OF GENERAL & INORGANIC CHEMISTRY, Kyiv-142, Ukraine;
Type of Paper: Regular
Id Paper: 241
Topic: 13
Abstract:
The peculiarities of the Li2CO3 electroreduction in pure carbonate and halide-carbonate melts have been studied by many authors [1-5]. This interest is due to the importance of this process for the production of nano-sized electrolytic carbon with a unique structure and morphology, since the solid-phase carbon deposition was carried out mainly from the salt melts containing lithium carbonate. However, there are wide differences in the obtained results. This is caused by the different research conditions. The authors, as a rule, studied the process at one depolarizer concentration, in a wide temperature, current and potential ranges, on different cathode materials and under the gaseous media of one composition. The purpose of this study was the voltammetric study of this process in a molten equimolar NaCl-KCl mixture in wide ranges of Li2CO3 concentrations (1.0-15.0×10-4 mol·cm-3) and polarization rates (0.02-0.10 mV·s-1) on platinum and glassy carbon cathodes in different gaseous media (air, in an inert atmosphere of argon and in an atmosphere of CO2) at a temperature of 750 °C.
It was found that the electroreduction of Li2CO3 in air occurs through the stage of a preliminary chemical reaction of acid-base type (Li2CO3 ⇄ Li2O + CO2) to form two electrochemically active particles: CO2 and LixCO32-x, which are reduced to elemental carbon at potentials of -0.8 and -1.7 V respectively against Pt|O2/O2- reference electrode. Both processes are irreversible, and the electroreduction of LixCO32-x takes place with diffusion control of the delivery of the depolarizer to the electrode surface.
Under of argon or carbon dioxide atmosphere over the melt, the process of lithium carbonate dissociation is suppressed; therefore, the deposition of carbon in this case occurs only from the cationized carbonate complex.
X-ray diffraction, SEM and Raman spectroscopy revealed that the cathode product is a high disordered amorphous carbon. Agglomerated particles consist of degraded graphite structures with an approximate crystallite size of 30–40 nm.
References:
[1] H. Kawamura and Y. Ito J. of Appl. Electroch. 30 (2000) 571–574.[2] Q. Song, Q. Xu, Y. Wang Thin Solid Films 520 (2012) 6856–6863.
[3] J. Ge, Sh. Wang, L. Hu, J. Zhu, Sh. Jiao Carbon 98 (2016) 649-657.
[4] J. Ge, L. Hu, Y. Song, S. Jiao Faraday Discuss 190 (2016) 259–268.
[5] B. Deng, J. Tang, M. Gao Electrochim Acta 259 (2018) 975–985.