Journal of Power Sources, Vol.276, 291-298, 2015
Electrochemical performance of hematite nanoparticles derived from spherical maghemite and elongated goethite particles
We report here an interesting observation on the electrochemical performance of hematite nanoparticles derived from cubic maghemite nanoparticles and hexagonal goethite rods prepared by a sonochemical process. We prepared hematite (alpha-Fe2O3) particles by annealing the as-prepared spherical cubic maghemite (gamma-Fe2O3) nanoparticles and rod shaped hexagonal goethite (alpha-FeOOH) particles at 600 degrees C in air and investigated their performance as a Li-ion battery anode. Interestingly, annealing of spherical maghemite particles resulted in the formation of plate like interconnected hematite particles exhibiting unimodal pore distribution whereas rod shaped goethite has resulted in the formation of irregularly shaped porous hematite particles having a wide and multimodal pore distribution. The plate like alpha-Fe2O3 cells delivered a reversible capacity of similar to 1160 and the porous alpha-Fe2O3 nanoparticles exhibited a slightly lower capacity of similar to 1100 mAh g(-1). The test cells rendered a reversible capacity of similar to 926 and similar to 841 mAh g(-1) for nanoparticles derived from maghemite and goethite, respectively, after 40 galvanostatic cycles and a capacity of 611 and 522 mAh g(-1) at 0.1C rate after 100 cycles. In other words, the investigated alpha-Fe2O3 nanomaterials retained a reversible capacity of similar to 80 and 75%, respectively after 40 galvanostatic cycles. The basic difference in the electrochemical performance of the studied hematite particles have been attributed to the difference in the porosity of the samples. Moreover, the adopted synthesis technique is very simple and easily up scalable compared to most of the methods available in the literature for the synthesis of hematite nanoparticles. (C) 2014 Elsevier B.V. All rights reserved.