Nano/microhierarchical-structured LiMn0.85Fe0.15PO4/C cathode materials were prepared by solvothermal synthesis combined with spray pyrolysis. XRD patterns and HRTEM images indicate that the LiMn0.85Fe0.15PO4/C are well crystallized and no impurity is observed. The as-prepared LiMn0.85Fe0.15PO4/C porous spheres (0.5-11 μm) are accumulated by primary nanoparticles (∼50 nm in width, 50-250 nm in length). Adopting sucrose as a carbon source, the cathode delivers a reversible discharge capacity of 171.2 mAh g-1 at 0.1C, almost exactly its theoretical capacity (∼170 mAh g-1). Moreover, the composite exhibits high cycle stability without apparent capacity fading after 100 cycles at rates of 0.1C and 1C. The outstanding electrochemical performances are partially due to Fe2+ substitution and carbon coating, which improve the electrical conductivity, and importantly, due to its nano-/microhierarchical structure where primary nanoparticles exhibit high electrochemical activity, abundant mesopores benefit electrolyte penetration and the hierarchical structure ensures cycling stability.
Keywords: LiMn0.85Fe0.15PO4; cathode material; nano-/microhierarchical structure; solvothermal synthesis; spray pyrolysis.