KVOPO4 cathode for sodium ion batteries
AssigneeThe Research Foundation for The State University of New York
InventorsM. Stanley Whittingham, Jia Ding
Life of this patent
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Abstract
An electrode comprising: NaVOPO4 having orthorhombic crystalline symmetry and space group Pna21, as an active intercalation host material, wherein the electrode is capable of electrochemical insertion and release of greater than one sodium ion per vanadium, wherein the NaVOPO4 is formed by a solid phase synthesis process from a heated powdered mixture of ammonium metavanadate, ammonium phosphate monobasic, and potassium carbonate, to yield KVOPO4 having corner-sharing VO6 octahedra and PO4 tetrahedra, defining two types of tunnels comprising a first type of tunnel formed of rings of two PO4 tetrahedra and a second type of tunnel formed of rings of three PO4 tetrahedra and three VO6 octahedra, followed by substitution of the potassium ions with sodium ions.
Claims20
An electrode comprising:
- NaVOPO4 having orthorhombic crystalline symmetry and space group Pna21, as an active intercalation host material,
- wherein the electrode is capable of electrochemical insertion and release of greater than one sodium ion per vanadium,
- wherein the NaVOPO4 is formed by a solid phase synthesis process from a heated powdered mixture of ammonium metavanadate, ammonium phosphate monobasic, and potassium carbonate, to yield KVOPO4 having corner-sharing VO6 octahedra and PO4 tetrahedra, defining two types of tunnels comprising a first type of tunnel formed of rings of two PO4 tetrahedra and a second type of tunnel formed of rings of three PO4 tetrahedra and three VO6 octahedra, followed by substitution of the potassium ions with sodium ions.
A reversible sodium battery comprising:
- a sodium donor anode;
- a sodium intercalation cathode comprising NaVOPO4, having a volume greater than 90 Å3 per VOPO4, orthorhombic crystalline symmetry, and space group Pna21,
- the NaVOPO4 being formed by a solid phase synthesis process from a heated powdered mixture of ammonium metavanadate, ammonium phosphate monobasic, and potassium carbonate, to yield KVOPO4 having corner-sharing VO6 octahedra and PO4 tetrahedra, defining two types of tunnels comprising a first type of tunnel formed of rings of two PO4 tetrahedra and a second type of tunnel formed of rings of three PO4 tetrahedra and three VO6 octahedra, followed by substitution of the potassium ions with sodium ions;
- a current collector configured to collect current from the sodium intercalation cathode;
- and
- an electrolyte comprising sodium ions.
An electrode for a reversible sodium battery, comprising NaVOPO4, having orthorhombic crystalline symmetry and space group Pna21 as an active ingredient capable of electrochemical insertion and release of sodium ions, having two well-separated voltage plateaus in a discharge curve of a battery formed with the electrode as cathode corresponding to at least two redox couples of vanadium cations,
- the NaVOPO4 being formed by a process comprising the steps of:
- 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 KVOPO4 occurs;
- milling the KVOPO4 together with conductive particles to form a conductive mixture of fine particles;
- adding binder material to form a conductive cathode material;
- and
- electrochemically removing potassium from the KVOPO4,
- wherein:
- said heating is at a temperature of between 600° C. and 800° C. for about 10 hours;
- the conductive particles comprise carbon particles;
- and
- the binder material comprises poly vinylidene fluoride.
Dependencies are inferred from the claim text.