Synthesis and properties of Li3V2-xCex(PO4)3/C cathode materials for Li-ion batteries

Ce-doped compounds Li(3)V(2-x)Cex(PO4)(3)/C (x = 0, 0.03, 0.05, 0.07, 0.10) were successfully prepared by a sol-gel process with CH3COO center dot 2H(2)O, NH4VO3, NH4H2PO4, citric acid and Ce(CH3COO)(3)center dot 5H(2)O as raw materials. X-ray diffraction analysis suggests that single-phase Li3V2-xCex(PO4)(3)/C with monoclinic structure can be obtained for x <= 0.10. The result of Rietveld refinement analysis indicates that cell volume increases with the increasing of the Ce content. As compared with the pure Li3V2(PO4)(3), although there is a small decrease in the initial specific capacity at low rate (0.2 C), a proper amount of Ce3+ doping, e. g. x = 0.05, could improve its cycle and rate performances. When discharge at 0.2 C and 10 C, the initial specific discharge capacities of Li3V1.95Ce0.05(PO4)(3) were 120 and 88.6 mAh g(-1) respectively. Furthermore, the capacity retention at the 100th cycle was 96.8% and 94.3% for the respective discharge capacities, which displayed excellent cycling properties. (C) 2012 Elsevier B.V. All rights reserved.