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Electrochemical Preparation of Fe2O3 Nanorods/Carbon Nanofiber Free-Standing Anode for Lithium Ion Batteries

Monday, 20 June 2016
Riverside Center (Hyatt Regency)
Y. Park, M. Oh, S. H. Baek, and J. H. Kim (DGIST)
Fe2O3 nanorod/carbon nanofiber (CNF) composites were prepared by the electrochemical deposition of Fe2O3 on a web of CNFs, which was then used as a free-standing anode. The conductive, three-dimensional structure of the CNF web allowed for the electrodeposition of the Fe2O3 nanorods, while its high conductivity made it possible to use the composite as a free-standing electrode in lithium-ion batteries. A free-standing electrode, which does not use polyber binder, substrate, and conductive additive, prevented a recution of rate-capability owing to the non-conductive polymer binder. In addition, it was easy and cheap to fabricate by a simplification of a process of cell preparation. The nanorod-like Fe2O3 structures could only be electrodeposited on the CNFs; flake-like Fe2O3 was formed on flat conductive glass substrates. It can be attributed to the different growth mechanism of Fe2O3 on the CNFs because of the large number of reaction sites on the CNFs, differences in the precursor concentration and diffusivity within the CNF web. The formation of aggregates of the Fe2O3 particles on thicker CNFs also indicated that the CNFs had determined the Fe2O3 growth mechanism. The synthesised Fe2O3/CNF composite electrode exhibited stable rate capacities at different current densities. This suggested that CNF-based composite did not exhibit the intrinsic disadvantages of Fe2O3. Finally, carbon coatings were deposited on the Fe2O3/CNF composites to further improve their electronic conductivity and rate capability. The strategy adopted in this study of using a web of CNFs as the substrate for the electrodeposition of Fe2O3 and of using the resulting composite material as a free-standing electrode  or LIBs should also be applicable in the case of other metal oxide/CNF composites.