Na based secondary battery

1. A Na based secondary battery comprising:

an anode containing sodium or a sodium alloy;

a cathode containing metal halide, wherein the metal halide comprises sodium metal halide and a halide of at least one metal selected from a group consisting of transition metals, and Groups 12 to 14 metals, a solvent dissolving the metal halide, and

a sodium ion conductive solid electrolyte separating the cathode and the anode from each other,

wherein the secondary battery is charged by a charge reaction according to the following Reaction Formula 1 and discharged by a discharge reaction according the following Reaction Formula 2

m NaX+M→ m Na+MX m   (Reaction Formula 1)

m NaX+M← m Na+MX m   (Reaction Formula 2)

wherein M is at least one metal selected from a group consisting of a group consisting of the transition metals and Groups 12 to 14 metals, X is a halogen atom, and m is a natural number of 1 to 4,

in which sodium halide (NaX) and metal halide (MX m ) of Reaction Formula 1 and 2 are dissolved by the solvent at the time of charging and discharging; and

the cathode further comprises excess NaX (naq)(con) wherein the halide ion X is the same or different from the halide ion of Reaction Formula 1 or 2, and

wherein (naq) means the NaX is dissolved in the solvent, and (con) means the NaX does not participate in the charge and discharge reaction of Formulas 1 and 2.

2. The Na based secondary battery of claim 1 , wherein in a discharge state, the cathode includes:

a liquid-state component containing sodium halide; and

a solid-state component containing at least one metal selected from a group consisting of the transition metals and Groups 12 to 14 metals.

3. The Na based secondary battery of claim 1 , wherein the solvent dissolves the entire metal halides.

4. The Na based secondary battery of claim 1 , wherein the cathode is in an entirely liquid state in a charge state.

5. The Na based secondary battery of claim 1 , further comprising a cathode current collector contacting the cathode to collect current and providing a current movement path to the outside.

6. The Na based secondary battery of claim 5 , wherein the cathode current collector contains at least one material selected from graphite, graphene, titanium, copper, platinum, aluminum, nickel, silver, gold, and carbon nanotube.

7. The Na based secondary battery of claim 1 , wherein M is at least one selected from nickel (Ni), iron (Fe), copper (Cu), zinc (Zn), cadmium (Cd), titanium (Ti), aluminum (Al), and tin (Sn), X is at least one selected from iodine (I), bromine (Br), chlorine (Cl), and fluorine (F).

8. The Na based secondary battery of claim 1 , wherein the cathode contains the metal halide at a concentration of 0.5 to 10 M.

9. The Na based secondary battery of claim 1 , wherein the sodium alloy is a sodium-cesium alloy, a sodium-rubidium alloy, or a mixture thereof.

10. The Na based secondary battery of claim 1 , wherein the solid electrolyte is beta alumina or Na super ionic conductor (NASICON).

11. The Na based secondary battery of claim 1 , wherein an operation temperature of the Na based secondary battery is room temperature to 200° C.

12. The Na based secondary battery of claim 1 , wherein the solvent is a non-aqueous organic solvent, an ionic liquid, or a mixture thereof.

13. The Na based secondary battery of claim 12 , wherein the solvent is at least one selected from a group consisting of 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butandiol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethylpropane-1,3-diol, 2-butyl-2-ethylpropane-1,3-diol, 1,5-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, 2,2,4,4-tetramethylcyclobutane-1,3-diol, 1,3-cyclopentanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediethanol, glycerol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, formamide, N,N-dimethyl formamide, N,N-dimethyl acetamide, N,N-diethyl acetamide, N,N-dimethyl trifluoroacetamide, hexamethylphosphoramide, acetonitrile, propionitrile, butyronitrile, α-terpineol, β-terpincol, dihydro terpineol, N-methyl-2-pyrrolidone (NMP), dimethylsulfoxide, pyrrolidine, pyrroline, pyrrole, 2H-pyrrole, 3H-pyrrole, pyrazolidine, imidazolidine, 2-pyrazoline, 2-imidazoline, 1H-imidazole, triazole, isoxazole, oxazole, thiazole, isothiazole, oxadiazole, oxatriazole, dioxazole, oxazolone, oxathiazole, imidazoline-2-thione, thiadiazole, triazole, piperidine, pyridine, pyridazine, pyrimidine, pyrazine, piperazine, triazine, morpholine, thiomorpholine, indole, isoindole, indazole, benzisoxazole, benzoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, benzoxazine, benzoadiazine, pteridine, phenazine, phenothiazine, phenoxazine, and acridine.

14. A Na based secondary battery comprising:

an anode containing sodium or a sodium alloy;

a cathode containing metal halide, wherein the metal halide comprises sodium metal halide and a halide of at least one metal selected from a group consisting of transition metals, and Groups 12 to 14 metals, a solvent dissolving the metal halide, and a sodium ion conductive solid electrolyte separating the cathode and the anode from each other,

wherein the secondary battery is charged by a charge reaction according to the following Reaction Formula 1 and discharged by a discharge reaction according the following Reaction Formula 2

m NaX+M→ m Na+MX m   (Reaction Formula 1)

m NaX+M← m Na+MX m   (Reaction Formula 2)

wherein M is at least one metal selected from a group consisting of a group consisting of the transition metals and Groups 12 to 14 metals, X is a halogen atom, and m is a natural number of 1 to 4, in which sodium halide (NaX) and metal halide (MX m ) of Reaction Formula 1 and 2 are dissolved by the solvent at the time of charging and discharging; and

wherein the cathode is in an entirely liquid state in a charge state, and

wherein the cathode contains the metal halide at a concentration of 0.1 to 10 M.