Synthesis and electrical property of Li2-xFeSi1-xPxO4 as positive electrodes by spark-plasma-sintering process

Li2-xFeSi1-xPxO4 was prepared with the intention of improving the electrical conductivity by taking advantage of the high lithium ionic conductivity of Li4SiO4-Li3PO4 solid solution. A monoclinic single phase by SPS process was obtained for x = 0, 0.1 and 0.2 in Li2-xFeSi1-xPxO4 and the process produced the samples in high dense in half an hour while their containing less than 3% of carbons. The electrical conductivity was increased by the replacing (SiO4)(4-) with (PO4)(3-), although the conductivity value itself was not reliable due to the carbon. The electrochemical properties of the samples using Li were evaluated and showed a slight improvement on the rate performance. A desired tetrahedral divalent Fe was confirmed in all investigated samples and ionic character caused by the localized 3d electron of Fe in the structure was encouraged by the complexation. (C) 2013 Elsevier B.V. All rights reserved.