Effect of sintering temperature on electrochemical performance of LiFe0.4Mn0.6PO4/C cathode materials

Carbon coated LiFe0.4Mn0.6PO4 (LiFe0.4Mn0.6PO4/C) was synthesised using high energy ball milling and annealing processes. The starting materials of Li2C2O4, FeC2O4.2H(2)O, MnC2O4.2H(2)O, NH4H2PO4 were firstly milled for 40 h, and followed by further milling for 5 h after adding glucose solution. The milled sample was heated at different temperatures (550, 600, 650 and 700 degrees C) for 10 h to produce LiFe0.4Mn0.6PO4/C composites. The structure and morphology of the samples were investigated using X-ray diffraction, field emission scanning electron microscopy, and high resolution electron microscopy. The phase of samples annealed at 550 and 600 degrees C mainly consists of olivine type LiFePO4, but a small amount of Fe2P impurity phase is formed in the samples annealed at 650 and 700 degrees C. Electrochemical analysis results show that LiFe0.4Mn0.6PO4/C synthesised at 600 degrees C exhibits the best performance with the initial discharge capacity of 128 mAh g(-1) at 0.1 C, and 109 mAh g(-1) at 1 degrees C after 500 cycles. The LiFe0.4Mn0.6PO4/C exhibits excellent electrochemical properties for high energy density lithium ion batteries.