Nano-/Microhierarchical-Structured LiMn_0.85Fe_0.15PO₄ Cathode Material for Advanced Lithium Ion Battery

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.