Stability, electrochemical behaviors and electronic structures of iron hydroxyl-phosphate

Iron hydroxyl-phosphate with a uniform spherical particle size of around 1 μm, a compound of the type Fe2−y□y(PO4)(OH)3−3y(H2O)3y−2 (where □ represents a vacancy), has been synthesized by hydrothermal methods. The particles are composed of spheres of diameter <100 nm. The compound exhibits good electrochemical performance, with reversible capacities of around 150 mAh g−1 and 120 mAh g−1 at current densities of 170 mA g−1 and 680 mA g−1, respectively. The stability of crystal structure of this material was studied by TGA and XRD which show that the material remains stable at least up to the temperature 200 °C. Investigation of the electronic structure of the iron hydroxyl-phosphate by GGA + U calculation has indicated that it has a better electronic conductivity than LiFePO4.