High Rate\nCapability of Hydrogen Annealed Iron Oxide–Single\nWalled Carbon Nanotube Hybrid Films for Lithium-Ion Batteries

Abstract

A facile\nand effective hydrogen annealing method has been demonstrated\nto synthesize iron oxide/SWNT hybrid films involving the thermal reduction\nof rhombohedral Fe₂O₃ to cubic Fe₃O₄ through the phase transformation while maintaining\nthe morphological integrity of the films. The poor rate capability\nand cyclic stability of the original α-Fe₂O₃/SWNT hybrid films have been significantly improved by H₂ annealing. The prepared iron oxide/SWNT hybrid films have a high\ncapacity of 786 mA h g^–1 at a high current density\nof 4 A g^–1 with a prolonged lifetime. The enhancement\nof the electrochemical performance is attributed to the presence of\nhighly conductive Fe₃O₄, accelerated charge-transfer\nkinetics, and the increased Li⁺ diffusivity confirmed by\nelectrochemical impedance spectra and galvanostatic intermittent titration.