Metal fluorides (MFx) are one of the most attractive cathode candidates for Li ion batteries (LIBs) due to their high conversion potentials with large capacities. However, only a limited number of synthetic methods, generally involving highly toxic or inaccessible reagents, currently exist, which has made it difficult to produce well-designed nanostructures suitable for cathodes; consequently, harnessing their potential cathodic properties has been a challenge. Herein, we report a new bottom-up synthetic method utilizing ammonium fluoride (NH4F) for the preparation of anhydrous MFx (CuF2, FeF3, and CoF2)/mesoporous carbon (MSU-F-C) nanocomposites, whereby a series of metal precursor nanoparticles preconfined in mesoporous carbon were readily converted to anhydrous MFx through simple heat treatment with NH4F under solventless conditions. We demonstrate the versatility, lower toxicity, and efficiency of this synthetic method and, using XRD analysis, propose a mechanism for the reaction. All MFx/MSU-F-C prepared in this study exhibited superior electrochemical performances, through conversion reactions, as the cathode for LIBs. In particular, FeF3/MSU-F-C maintained a capacity of 650 mAh g-1FeF3 across 50 cycles, which is ∼90% of its initial capacity. We expect that this facile synthesis method will trigger further research into the development of various nanostructured MFx for use in energy storage and other applications.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (NRF-2013R1A1A2074550 and NRF-2016R1A4A1010735). This research was further supported by C1 Gas Refinery Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2015M3D3A1A01065440). This research was further supported by the 2016 Research Fund (1.160004.01) of UNIST (Ulsan National Institute of Science and Technology).
All Science Journal Classification (ASJC) codes
- Materials Science(all)