Hierarchical structured LiMn_0.5Fe_0.5PO₄ spheres synthesized by template-engaged reaction as cathodes for high power Li-ion batteries

Porous hierarchical LiMn_0.5Fe_0.5PO₄ spheres were synthesized via a novel template-engaged method using pre-synthesized hollow spherical Li₃PO₄ as template and FeCl₂·4H₂O/MnCl₂·4H₂O as Fe²⁺/Mn²⁺ source. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the porous hierarchical spheres exhibit hollow structure and have a size distribution of 0.4–1 um consisting of aggregated ∼50 nm nanoparticles. A mechanism of the reaction from Li₃PO₄ to LiMn_0.5Fe_0.5PO₄ was proposed on the basis of the phase and morphology transformation of the intermediates. With the short Li⁺ diffusion path and porous structure, the carbon coated LiMn_0.5Fe_0.5PO₄ spheres show high specific capacity and superior rate capability with the discharge capacities of 159.3 mA h g⁻¹ at 0.1C and 80.6 mA h g⁻¹ at 20C. The porous hierarchical spheres also exhibit an excellent cycling stability with about 90.7% of the initial value at 1C after 100 cycles.