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

Nano/microhierarchical-structured LiMn_0.85Fe_0.15PO₄/C cathode materials were prepared by solvothermal synthesis combined with spray pyrolysis. XRD patterns and HRTEM images indicate that the LiMn_0.85Fe_0.15PO₄/C are well crystallized and no impurity is observed. The as-prepared LiMn_0.85Fe_0.15PO₄/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.