Spherical Ni-doped LiMn0.6Fe0.4PO4/C composites with high-rate performance

In this paper, Ni-doped spherical LiMn0.6Fe0.4PO4/C cathode materials are successfully synthesized by a combination of wet ball milling, spray drying, and carbon thermal reduction. The lattice distortion produced by the appropriate amount of Ni doping can reduce the surface energy of LiMn0.6Fe0.4PO4 crystals, which can also inhibit the crystals' growth and keep the crystals in a suitable size and regular shape. The prepared spherical LiMn0.6Fe0.4PO4 cathode materials feature a smooth surface, good sphericity, appropriate particle size, ideal lattice volume, and high phase purity, which exhibit excellent cycling performance and rate capability. After 100 charge/discharge cycles at 1 C, the capacity of LiMn0.6Fe0.38Ni0.02PO4 cathode decreases only slightly to 147.3 mAh g(-1), corresponding to a capacity retention rate of 98.3%. The discharge capacity can also reach 125.1 and 115.4 mAh g(-1) at high rates of 10 C and 15 C.