Preparation, characterization and electrochemical property of Sn-Fe-Mo-Al2O3 multi-phase composites

A novel technique has been developed to synthesize Sn-Fe-Mo-Al2O3, while nanoscale dispersion of a highly active tin phase was finely distributed in a stable inert multi-phase. The precursor was prepared by co-precipitation method with SnCl4, FeCl3, AlCl3 and (NH4)(6)Mo7O24 as the raw materials. Sn-Fe-Mo-Al2O3 mixture was produced by reducing the precursor with H-2. The product was characterized by X-ray diffraction (XRD), ICP and scanning electron microscopy (SEM). The performance of the electrode was investigated. The Sn-Fe-Mo-Al2O3 electrode was found to have an initial charge capacity of over 461 mAh/g, and a reversible volumetric capacity of 2090 mAh/cm(3), which is two times larger than that of graphite electrode (800 mAh/cm(3)). The coulomb efficiency in the first cycle was over 55%, but its cyclability was not improved significantly. In order to enhance the cycle performance, we investigated the anode after heat treated at 270 degrees C for 12 h. Under the same condition, the first charge-discharge characteristics were almost equivalent to the as-coated anode, and the retention capacity ratio after 20 cycles was improved from 41.1% to 86.5%. The heat-treated Sn-Fe-Mo-Al2O3 electrode exhibited better cycle life. The electrochemical reaction of the Sn-Fe-Mo-Al2O3 electrode with Li may obey the alloying-dealloying mechanism of LixSn(x <= 4.4) formation in the other tin-based electrodes. (C) 2008 Elsevier Ltd. All rights reserved.