Editors: | F. Kongoli, H. Dodds, M. Mauntz, T. Turna, V. Kumar, K. Aifantis |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2018 |
Pages: | 170 pages |
ISBN: | 978-1-987820-98-0 |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
The development of advanced electrode materials for secondary Li batteries is essential to meet the increased energy demands posed by portable electronic devices and the rapid growth of electrical vehicles and energy storage systems.[1] In order to replace the intercalation reaction-based materials that have capacity limitations, many researchers have focused on new electrode materials reacting through conversion or alloying reactions, which can take up multiple Li-ions per unit formula.[2]
In this study, using ammonium fluoride (NH<sub>4</sub>F), we developed a new synthetic route to fabricate metal fluoride (MF<sub>x</sub>) nanocomposites for conversion reaction-based high capacity cathodes and nanostructured silicon (Si) for alloying reaction-based high capacity anodes. At first, we discovered that various anhydrous MF<sub>x</sub> can be obtained through simple heat treatment of metal precursors with NH<sub>4</sub>F under an inert atmosphere. Based on this process, MF<sub>x</sub>/mesoporous carbon nanocomposites were successfully synthesized.[3] From the reaction mechanism of this synthetic method, we expected that residual impurities in the raw Si materials, such as SiO<sub>2</sub>, could be easily removed using NH<sub>4</sub>F. Interestingly, the reaction of raw Si materials with NH<sub>4</sub>F not only removed residual SiO<sub>2</sub>, but also generated nanopores on Si. When used as electrodes in Li batteries, the MF<sub>x</sub> nanocomposites and nanostructured Si showed noticeable improvements in electrochemical performance. It is expected that this study will motivate further research into the synthesis of advanced electrode materials for secondary batteries using NH<sub>4</sub>F.