Effects of roasting temperature and modification on properties of Li2FeSiO4/C cathode

Li2FeSiO4/C cathodes were synthesized by combination of wet-process method and solid-state reaction at high temperature, and effects of roasting temperature and modification on properties of the Li2FeSiO4/C cathode were investigated. The XRD patterns of the Li2FeSiO4/C samples indicate that all the samples are of good crystallinity, and a little Fe3O4 impurity was observed in them. The primary particle size rises as the roasting temperature increases from 600 to 750 degrees C. The Li2FeSiO4/C sample synthesized at 650 degrees C has good electrochemical performances with an initial discharge capacity of 144.9 mAh g(-1) and the discharge capacity remains 136.5 mAh g(-1) after 10 cycles. The performance of Li2FeSiO4/C cathode is further improved by modification of Ni substitution. The Li(2)Fe(0.9)gNi(0.1)SiO(4)/C composite cathode has an initial discharge capacity of 160.1 mAh g(-1), and the discharge capacity remains 153.9 mAh g(-1) after 10 cycles. The diffusion coefficient of lithium in Li2FeSiO4/C is 1.38 x 10(-12) cm(2) s(-1) while that in Li(2)Fe(0.9)gNi(0.1)SiO(4)/C reaches 3.34 x 10(-12) cm(2) s(-1). (C) 2008 Elsevier B.V. All rights reserved.