Electrochimica Acta, Vol.78, 576-584, 2012
Effects of titanium incorporation on phase and electrochemical performance in LiFePO4 cathode material
Ti-incorporated LiFe1-xTixPO4 (0 <= x <= 0.2) samples have been prepared via a two-step solid-state reaction route. The samples have systematically been investigated with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), cyclic voltammetry (CV) and charge/discharge measurements. The incorporation of Ti in LiFePO4 significantly enhances the electrochemical performance; the carbon-coated LiFe0.9Ti0.1PO4 sample shows the best performance. It is confirmed that LiFe1-xTixPO4 with x <= 0.05 are of single phase while those with 0.07 <= x <= 0.2 contain impurity phases: LiTi2(PO4)(3) and TiP2O7. The impurities influence not only the electronic conductivity, but also the total specific capacity. Appropriate amount of titanium incorporation is favorable for the improvement in electrochemical performance. (C) 2012 Elsevier Ltd. All rights reserved.
Keywords:Lithium-ion batteries;Lithium iron phosphate;Cathode;Titanium incorporation;Electrochemical performance