Iron Oxide Nanosheets and Nanoparticles Synthesized by a Facile Single-Step Coprecipitation Method for Lithium-Ion Batteries

The nanostructured iron oxides were synthesized by a simple coprecipitation technique at room temperature and tested as the anode materials for lithium-ion batteries. The iron salt precursor has a significant effect on the morphology evolution of the iron oxide. The nanosheet and nanoparticle samples were obtained by using ferrous ammonium sulfate and ferric chloride precursors, respectively. Both samples could be identified as alpha-Fe2O3 after annealing at 400 degrees C. The electrical conductivity of the nanosheet sample was higher than that of the nanoparticle sample due to its sheet morphology and small grain size. The galvanostatic charge/discharge results indicated that the alpha-Fe2O3 nanosheet anode (1327 mAh g(-1)) has a higher reversible capacity than the alpha-Fe2O3 nanoparticle anode (1006 mAh g(-1)) at 1 C current rate. More importantly, the nanosheet anode exhibited a high capacity of 1215 mAh g(-1) at 3 C current rate; this value is much higher than the nanoparticle anode 9812 mAh g(-1)). The improved performance of the iron oxide nanosheet toward lithium could be attributed to the high electrical conductivity and small grain size for facilitating the transport of the electrons and lithium ions through the nanosheet. (C) 2011 The Electrochemical Society. [DOI:10.1149/1.3527982] All rights reserved.