2017-Sustainable Industrial Processing Summit
SIPS 2017 Volume 7. Recycling, Secondary Batteries and Environmental Protection
| Editors: | Kongoli F, Aifantis K, Kumar V, Pagnanelli F, Kozlov P, Xueyi G |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2017 |
| Pages: | 205 pages |
| ISBN: | 978-1-987820-73-7 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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A New Synthetic Route to Anhydrous Metal Fluoride Nanocomposites for High Capacity Cathodes of Secondary Li Batteries
Jinyoung Chun1; Jinwoo Lee2;1KOREA INSTITUTE OF CERAMIC ENGINEERING & TECHNOLOGY (KICET), Jinju, Korea (Republic of [South] Korea); 2POSTECH, Pohang, Korea (Republic of [South] Korea);
Type of Paper: Regular
Id Paper: 95
Topic: 14
Abstract:
Metal fluorides (MFx) are known as promising cathode materials for secondary Li batteries that exhibit high theoretical operating voltages as well as large specific capacities. The high ionicity of M-F bonds results in higher reaction potentials that other metal compounds, and multiple Li ions per unit formula participated in the charge/discharge process based on conversion reactions. However, a limited number of synthetic methods for preparing MFx electrodes currently exist, which has made it difficult to control the morphology of particles and fabricate designed nanostructures to alleviate the intrinsic chemical and electrochemical drawbacks of MFx.<br /> In this study, we developed a new synthetic route to anhydrous MFx(CuF2, FeF3, and CoF2) nanocomposites using ammonium fluoride(NH4F). We discovered that various metal precursors can be directly converted to anhydrous MFx through heat treatment with NH4F under an inert atmosphere. This simple, less-hazardous, and versatile method enabled synthesis of MFx nanoparticles confined in nanoporous carbon efficiently. Moreover, using XRD analysis, we also proposed the reaction mechanism of this synthetic method. As the cathodes of secondary Li batteries, all MFx nanocomposites (MFx/nanoporous carbon) showed noticeable improvements in electrochemical performance through conversion reactions. Especially, in the case of FeF3 nanocomposites, it maintained a capacity of 650 mAh/g,FeF3 over 50 cycles (~90% of its initial capacity); to the best of our knowledge, no such a superior cyclability of FeF3 with a high capacity has been reported previously. CuF2 and CoF2 nanocomposites also maintained discharge capacities of ~200 mAh/g,CuF2 (20th cycle) and ~400 mAh/g,CoF2 (30th cycle), respectively. It is expected that this study will motivate further research into various MFx for high capacity cathodes of secondary batteries.