Sodium nickel phosphate cathodes used for sodium-ion rechargeable batteries

Abstract

Although the traditional lithium-ion batteries have high capacities and performances, the price of those batteries increases rapidly. Sodium-ion batteries are predicted to be a suitable replacement for lithium-ion batteries in the future. In this case a suitable cathode for a sodium-ion battery was synthesized using a sodium nickel phosphate composite. The material was prepared using a solid state reaction of sodium phosphate and nickel (II) oxide. The synthesized material was characterized using a powder X-Ray diffraction method. The cathode was fabricated on aluminum foil using the synthesized material mixed with carbon black and polyvinylidene fluoride. Sodium metal pressed onto a copper plate was used as the cathode. After the fabrication of the cell, charge-discharge cycles and impedance measurements were performed to identify the electrochemical properties of the cell. The full discharge capacity of the cell was calculated to be 50.53 mA h g-1. The high capacity of the cell indicates contribution from oxidation and reduction of cathode material other than the intercalation chemistry of lithium ions, which needs to be further investigated.