VOPO4 CATHODE FOR SODIUM ION BATTERIES

An electrode comprising a space group Pna2VOPOlattice, capable of electrochemical insertion and release of alkali metal ions, e.g., sodium ions. The VOPOlattice may be formed by solid phase synthesis of KVOPO, milled with carbon particles to increase conductivity. A method of forming an electrode is provided, comprising milling a mixture of ammonium metavanadate, ammonium phosphate monobasic, and potassium carbonate; heating the milled mixture to a reaction temperature, and holding the reaction temperature until a solid phase synthesis of KVOPOoccurs; milling the KVOPOtogether with conductive particles to form a conductive mixture of fine particles; and adding binder material to form a conductive cathode. A sodium ion battery is provided having a conductive NaVOPOcathode derived by replacement of potassium in KVOPO, a sodium ion donor anode, and a sodium ion transport electrolyte. The VOPO, preferably has a volume greater than 90 Åper VOPO.