Electrochemically deposited Fe2O3 nanorods on carbon nanofibers for free-standing anodes of lithium-ion batteries

Abstract

Fe<inf>2</inf>O<inf>3</inf> nanorod/carbon nanofiber (CNF) composites were prepared by the electrochemical deposition of Fe<inf>2</inf>O<inf>3</inf> 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 Fe<inf>2</inf>O<inf>3</inf> nanorods, while its high conductivity made it possible to use the composite as a free-standing electrode in lithium-ion batteries. In addition, it was easy and cheap to fabricate by a simplification of a process of cell preparation. The nanorod-like Fe<inf>2</inf>O<inf>3</inf> structures could only be electrodeposited on the CNFs; flake-like Fe<inf>2</inf>O<inf>3</inf> was formed on flat conductive glass substrates. It can be attributed to the different growth mechanism of Fe<inf>2</inf>O<inf>3</inf> 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 Fe<inf>2</inf>O<inf>3</inf> particles on thicker CNFs also indicated that the CNFs had determined the Fe<inf>2</inf>O<inf>3</inf> growth mechanism. The synthesised Fe<inf>2</inf>O<inf>3</inf>/CNF composite electrode exhibited stable rate capacities at different current densities. This suggested that CNF-based composite did not exhibit the intrinsic disadvantages of Fe<inf>2</inf>O<inf>3</inf>. Finally, carbon coatings were deposited on the Fe<inf>2</inf>O<inf>3</inf>/CNF composites to further improve their electronic conductivity and rate capability. © 2015 Elsevier Ltd. All rights reserved.