Simple synthesis of novel phosphate electrode materials with unique microstructure and enhanced supercapacitive properties

Flower-like Ni3P2O8 and flower-like Fe3P2O8·8H2O have been successfully synthesized by a simple chemical precipitation method. X-ray diffraction (XRD) patterns reveal an amorphous phase formation of nickel phosphate (Ni3P2O8) and pure monoclinic phase of Fe3P2O8·8H2O. The novel flower-like Ni3P2O8 and flower-like Fe3P2O8·8H2O when used for supercapacitor electrode materials exhibit a high specific capacitance (Cm) of 1464 F/g and 200 F/g at a current density of 0.5 A/g, respectively. Eventually, an asymmetric supercapacitor is fabricated using Ni3P2O8 as positive electrode and Fe3P2O8·8H2O as negative electrode. A high specific capacitance of 94 F/g is achieved in the high-voltage region of 0 ∼1.6 V, and a large energy density of 32.6 Wh/kg is delivered at power density of 420 W/kg. The findings demonstrate the important and great potential of developing metal phosphate based materials for supercapacitors.