KR20180025998A - Electrolyte solution comprising sulfur dioxide based Fe inorganic electrolyte and sodium-sulfur dioxide secondary battery having the same - Google Patents

Abstract

Disclosed are an electrolyte solution comprising sulfur dioxide based Fe inorganic electrolyte and a sodium-sulfur dioxide secondary battery having the same. The sodium-sulfur dioxide secondary battery of the present invention comprises an electrolyte containing a sulfur dioxide based Fe inorganic electrolyte, which is produced by injecting SO_2 gas into a mixture of a cathode of an inorganic material containing sodium, an anode of a carbon material, NaX and FeX_n. The X is a halogen compound, a saturated hydrocarbon (R) having C1 to C20, and an unsaturated hydrocarbon (R) having C1 to C20, OR or SR, and n denotes an integer of 0 to 10. According to the present invention, it is possible to improve the overall energy efficiency of the battery by reducing severe polarization phenomenon occurring in the evaluation of cells.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolyte containing sulfur-based iron-based inorganic electrolyte and a sodium-sulfur dioxide secondary battery having the same.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sodium-based secondary battery, and more particularly, to an electrolyte containing sulfur-based iron-based inorganic electrolyte using iron and a sodium-sulfur dioxide secondary battery having the electrolyte.

As consumers' demands have changed due to digitization and high performance of electronic products, market demand is changing due to the development of batteries with high capacity due to thinness, light weight and high energy density. In addition, in order to cope with future energy and environmental problems, development of hybrid electric vehicles, electric vehicles and fuel cell vehicles has been actively promoted, and it is required to increase the size of batteries for automobile power sources.

Lithium secondary batteries have been put to practical use as batteries that can be miniaturized and lightweight and can be recharged with a high capacity, and are used in portable electronic devices and communication devices such as small video cameras, mobile phones, laptops, and the like. The lithium secondary battery is composed of a positive electrode, a negative electrode and an electrolyte. Since lithium ions discharged from the positive electrode active material by charging are inserted into the negative electrode active material and are discharged again, / Discharge is possible.

Recently, research on sodium-based secondary batteries using sodium instead of lithium has been reexamined. Since sodium is abundant in resource reserves, secondary batteries can be manufactured at low cost if sodium secondary batteries can be manufactured instead of lithium.

As described above, sodium-based secondary batteries are useful, but conventional sodium-metal based secondary batteries such as NAS (Na-S battery) and ZEBRA (Na-NiCl ₂ battery) can not be used at room temperature, There is a problem in terms of battery safety due to the use of liquid sodium and positive electrode active material and deterioration of battery performance due to corrosion problems. Accordingly, there is a demand for a sodium-based secondary battery which is usable at room temperature and is excellent in energy density and lifetime characteristics.

In order to solve this problem, a sodium-sulfur dioxide (Na-SO ₂ ) secondary battery has been introduced. The sodium-sulfur dioxide secondary battery is a new battery system that can be used as a power source for large-capacity power storage by using a material at room temperature molten salt as an electrolyte to significantly improve the low energy density of existing lithium secondary batteries.

Particularly, the sodium-sulfur dioxide secondary battery is a new battery system having an advantage that it can lower the price to less than half of the existing lithium secondary battery by using sodium (Na) which is inexpensively cheap.

However, the sodium-sulfur dioxide secondary battery based on the conventional aluminum (Al) based electrolyte is required to be improved due to the price difficulties of the materials used in the electrolyte production, and studies have been conducted to overcome such price difficulties It is true.

Korean Registered Patent No. 10-160014 (Apr.

An object of the present invention is to provide an electrolytic solution containing a sulfur-based iron-based inorganic electrolyte and a sodium-sulfur dioxide secondary battery having the same.

Another object of the present invention is to provide an electrolyte containing a sulfur-based iron-based inorganic electrolyte which improves the overall energy efficiency of the battery by improving a severe polarization phenomenon occurring in the evaluation of a battery, and a sodium-sulfur dioxide secondary battery having the electrolyte .

To achieve the above object, sodium according to the invention the sulfur dioxide secondary battery, sulfur dioxide was prepared by injecting the SO ₂ gas to the negative electrode, a positive electrode, a mixture of NaX and FeX _n of the carbon material of inorganic material containing sodium based And an electrolyte containing an iron-based inorganic electrolyte. Wherein X is a halogen compound, a saturated hydrocabon (R) having C1 to C20, an unsaturated hydrocabon (R) having C1 to C20, OR or SR, and n denotes an integer of 0 to 10.

And the molar ratio of NaX and FeX _n is 2.0: 1.0 to 1.0: 2.0.

The sulfur-based iron-based inorganic electrolyte is characterized by being NaFeCl ₄ -xSO ₂ (1.5? X? 3.0).

The electrolytic solution may also contain other sulfur dioxide-based weapons, such as NaAlCl ₄ , Na ₂ CuCl ₄ , Na ₂ MnCl ₄ , Na ₂ CoCl ₄ , Na ₂ NiCl ₄ , Na ₂ ZnCl ₄ and Na ₂ PdCl ₄ , And further includes an electrolyte.

Wherein the electrolyte is a mixture of the sulfur-based iron-based inorganic electrolyte and the other sulfur dioxide-based inorganic electrolyte.

The electrolyte for a sodium-sulfur dioxide secondary battery according to the present invention includes an inorganic sulfur dioxide-based inorganic electrolyte prepared by injecting SO ₂ gas into a mixture of NaX and FeX _n . Wherein X is a halogen compound, a saturated hydrocabon (R) having C1 to C20, an unsaturated hydrocabon (R) having C1 to C20, OR or SR, and n denotes an integer of 0 to 10.

And the molar ratio of NaX and FeX _n is 2.0: 1.0 to 1.0: 2.0.

In addition, NaAlCl ₄ , Na ₂ CuCl ₄ , Na ₂ MnCl ₄ , Na ₂ CoCl ₄ , Na ₂ NiCl ₄ , Na ₂ ZnCl ₄ And Na ₂ PdCl ₄ Based inorganic electrolyte using any one solute of the sulfur dioxide-based inorganic electrolyte.

The electrolyte containing the sulfur-based iron-based inorganic electrolyte according to the present invention and the sodium-sulfur dioxide secondary battery having the electrolyte according to the present invention can reduce the manufacturing cost by constituting the electrolytic solution using iron which is inexpensive.

In addition, it is possible to improve the overall energy efficiency of the battery by improving the severe polarization phenomenon occurring in the battery evaluation.

In addition, it is possible to improve a lifetime characteristic and realize a stable secondary battery.

1 is a view for explaining a sodium-sulfur dioxide secondary battery according to an embodiment of the present invention.
2 is a view for explaining the production of a sulfur-based iron-based inorganic electrolyte according to an embodiment of the present invention.
3 is a graph illustrating the battery characteristics of a sodium-sulfur dioxide secondary battery according to an embodiment of the present invention.
FIG. 4 is a graph illustrating the battery characteristics of a sodium-sulfur dioxide secondary battery according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals as used in the appended drawings denote like elements, unless indicated otherwise. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather obvious or understandable to those skilled in the art.

FIG. 1 is a view for explaining a sodium-sulfur dioxide secondary battery according to an embodiment of the present invention, and FIG. 2 is a view for explaining the production of a sulfur-based iron-based inorganic electrolyte according to an embodiment of the present invention.

1 and 2, the sodium-sulfur dioxide secondary battery 100 includes an anode 20, a cathode 30, and an electrolyte 10. [ At this time, the sodium-sulfur dioxide secondary battery 100 may further include a case 40.

The anode 20 is made of a porous carbonaceous material and provides a place where the oxidation-reduction reaction of the sulfur dioxide-based inorganic electrolyte takes place. The carbon material constituting the anode 20 may include one or two or more different elements depending on the case. Here, the heteroelement means nitrogen (N), oxygen (O), boron (B), fluorine (F), phosphorus (P), sulfur (S) and silicon (Si). The content of the hetero-element may be 0 to 20 at%, preferably 5 to 15 at%. In this case, when the content of heteroatoms is less than 5 at%, the effect of increasing the capacity by adding the heteroelement is insignificant, and when the content of 15 at% or more, the electrical conductivity of the carbonaceous material and the ease of electrode formation are decreased.

The anode 20 may further include a metal chloride, a metal fluoride or a metal bromide in the porous carbon material.

Here, the metal chloride is _{CuCl 2, CuCl, NiCl 2,} FeCl 2, FeCl 3, CoCl 2, MnCl 2, CrCl 2, CrCl 3, VCl 2, VCl 3, ZnCl 2, ZrCl 4, NbCl 5, MoCl 3, MoCl _{5, RuCl 3, RhCl 3,} PbCl 2, may include AgCl, CdCl least one or both of the _two. CuCl ₂ reacts with sodium ions while changing the oxidation number of Cu at the time of charging and discharging, so that the discharge product of Cu and NaCl is obtained, and CuCl ₂ is reversibly reversed upon charging. The content of the metal chloride in the anode 20 is 50 to 100% by weight or 60 to 99% by weight and preferably 70 to 95% by weight for the purpose of compounding additional elements for improving the characteristics of the anode 20 .

Metal fluoride is _{CuF 2, CuF, NiF 2,} FeF 2, FeF 3, CoF 2, CoF 3, MnF 2, CrF 2, CrF 3, ZnF 2, ZrF 4, ZrF 2, TiF 4, TiF 3, NbF 5, AgF ₂ , SbF ₃ , GaF ₃ , and NbF ₅ . The anode 20 may comprise a porous carbonaceous material and a constant weight ratio of CuF ₂ . CuF ₂ reacts with sodium ions while changing the oxidation number of Cu at the time of charging and discharging, so that the discharge product of Cu and NaCl is obtained, and CuF ₂ is reversibly reversed upon charging. The content of the metal fluoride in the anode 20 is 50 to 100% by weight or 60 to 99% by weight, and preferably 70 to 95% by weight for the purpose of compounding additional elements for improving the characteristics of the anode 20 .

Metal bromide is _{CuBr 2, CuBr, NiBr 2,} FeBr 2, FeBr 3, CoBr 2, MnBr 2, CrBr 2, ZnBr 2, ZrBr 4, ZrBr 2, TiBr 4, TiBr 3, NbBr 5, AgBr, SbBr 3, GaBr ₃ , NbBr ₅ , BiBr ₃ , MoBr ₃ , SnBr ₂ , WBr ₆ and WBr ₅ . The anode 20 may comprise a porous carbonaceous material and a constant weight ratio of CuBr ₂ . CuBr ₂ reacts with sodium ions while changing the oxidation number of Cu at the time of charging and discharging to obtain a discharge product of Cu and NaCl, and reversibly forms CuBr ₂ upon charging. The content of the metal bromide in the anode 20 is 50 to 100% by weight or 60 to 99% by weight, and preferably 70 to 95% by weight for compounding additional elements for improving the characteristics of the anode 20 have.

The cathode 30 can be made of a sodium metal, an alloy containing sodium, an intermetallic compound containing sodium, a carbon material containing sodium, an inorganic material containing sodium, or the like. The inorganic material may include at least one of an oxide, a sulfide, a phosphide, a nitride, and a fluoride. The content of the cathode material in the cathode 30 may be 60 to 100% by weight.

The sulfur dioxide-based inorganic electrolyte 10 used as an electrolyte and an anode reaction active material uses an iron-based inorganic electrolyte (hereinafter, referred to as an iron-based inorganic electrolyte) capable of chelation but weakly binding with sulfur dioxide.

The iron-based inorganic electrolytes include NaX and FeX _n And SO ₂ . Here, X may be a ligand, for example, various ligands including halogen compounds, saturated or unsaturated hydrocarbon (R) having 1 to 20 carbon atoms, OR, SR and the like. Specifically, the ligand is ^{COOH, -COO -, -CHO, -NH} 2, -SH, -OH, -SO 3 H, -SO 3 -, -C (= NH) -, -CONH 2, -CN, -CS ₂ H, -CS ₂ ^- , a halide group (-CL, -F, Br, etc.), a pyridine group, and a pyrazine group.

At this time, the molar ratio of NaX and FeX _n may be 2.0: 1.0 to 1.0: 2.0. Here, n is an integer of 0 to 10.

The iron-based inorganic electrolyte may be composed of NaFeCl ₄ (solute) and SO ₂ (solvent). That is, NaFeCl ₄ -xSO ₂ is prepared by injecting SO ₂ gas into a mixture of NaCl and FeCl ₃ (or a salt of NaFeCl ₄ alone). Here, x is 1.5? X? 3.0.

The electrolyte of NaFeCl ₄ -xSO _{2 has} a molar ratio (x) of SO ₂ to NaFeCl ₄ of 0.5 to 10, preferably 1.5 to 3.0. That is, when the molar ratio of SO ₂ is lowered to less than 1.5, the electrolyte ion conductivity decreases. When the molar ratio of SO ₂ is higher than 3.0, the vapor pressure of the electrolyte increases.

In one embodiment, as shown in FIG. 2, an electrolyte solution may be prepared by mixing NaCl and FeCl ₃ at a ratio of 1.1: 1.0 and then injecting SO ₂ gas. .

On the other hand, the iron-based inorganic electrolyte can be used alone as the sulfur dioxide-based electrolyte 10, but it can be used in combination with other sulfur dioxide-based inorganic electrolytes. For example, NaFeCl ₄ In addition to being used as a _{solute, NaAlCl 4, Na 2 CuCl 4} , Na 2 MnCl 4, Na 2 CoCl 4, Na 2 NiCl 4, Na 2 ZnCl 4 and Na ₂ PdCl ₄ any one of the with the NaFeCl ₄ Can be used. That is, NaFeCl ₄ can be used with other sulfur dioxide-based inorganic electrolytes, in which case it can be used as a mixture.

The case 40 may be provided to enclose an arrangement in which the electrolyte solution 10 is disposed between the anode 20 and the cathode 30. [ A signal line connected to the anode 20 and a signal line connected to the cathode 30 are disposed on one side of the case 40. The shape and size of the case 40 may be determined according to the field to which the sodium-sulfur dioxide secondary battery 100 is applied. The case 40 is made of a nonconductive material, but may be formed of an electrically conductive material when the insulator that surrounds the anode 20 and the cathode 30 is provided.

The sodium-sulfur dioxide secondary battery 100 using the iron-based inorganic electrolyte can be used at a temperature of 50 to 300 ° C and a current of 0.001 to 1000 ° C. The sodium-sulfur dioxide secondary battery 100 has an electrode density of 0.01 to 100 mg / cm ² , an electrolyte 10 injected amount of 10 μg to 1 g, and can be manufactured in various battery types. For example, a coin cell, a beaker cell, a pouch cell, a cylindrical cell, a square cell, or the like.

FIG. 3 is a graph illustrating the battery characteristics of a sodium-sulfur dioxide secondary battery according to an embodiment of the present invention, and FIG. 4 is a graph illustrating battery characteristics of a sodium-sulfur dioxide secondary battery according to an embodiment of the present invention. Here, the evaluation conditions were 2.3 to 0.1 V (vs. Na / Na +) and 0.1C / 0.1C.

Referring to FIG. 3, the average discharge voltage of the NaFeCl ₄ -xSO ₂ electrolyte according to an embodiment of the present invention was found to be charged / discharged at about 0.75 V, and a discharge capacity of about 1500 mAh / .

This result means that the electrolyte 10 of the present invention enables the operation of the sodium-sulfur dioxide secondary battery 100. Therefore, it is believed that the electrolytic solution 10 using relatively inexpensive iron can be applied to middle-sized and large-sized secondary batteries such as ESS (Energy Storage System) and electric vehicles.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation in the embodiment in which said invention is directed. It will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the appended claims.

10: electrolyte
20: anode
30: cathode
40: Case
100: Sodium-sulfur dioxide secondary battery

Claims (8)

An anode of an inorganic material containing sodium;
Anode of carbon material;
An electrolyte solution containing an iron-based inorganic electrolyte based on sulfur dioxide prepared by injecting SO ₂ gas into a mixture of NaX and FeX _n ;
≪ / RTI >
(X is a halogen compound, saturated hydrocabon (R) having C1 to C20, unsaturated hydrocabon (R) having C1 to C20, OR or SR, and n is an integer of 0 to 10) The method according to claim 1,
Wherein the molar ratio of NaX and FeX _n is 2.0: 1.0 to 1.0: 2.0. The method according to claim 1,
Iron-based inorganic electrolyte in the sulfur dioxide-based sodium, characterized in that NaFeCl ₄ -xSO ₂ (1.5≤x≤3.0) - sulfur secondary cell. The method according to claim 1,
The electrolyte solution,
Further comprising other sulfur dioxide-based inorganic electrolytes using any one of NaAlCl ₄ , Na ₂ CuCl ₄ , Na ₂ MnCl ₄ , Na ₂ CoCl ₄ , Na ₂ NiCl ₄ , Na ₂ ZnCl ₄ and Na ₂ PdCl ₄ Lt; RTI ID = 0.0 > sodium-sulfur dioxide < / RTI > 5. The method of claim 4,
The electrolyte solution,
A sulfur-based iron-based inorganic electrolyte, and the other sulfur dioxide-based inorganic electrolyte. Based sulfur-containing inorganic electrolytes prepared by injecting SO ₂ gas into a mixture of NaX and FeX _n ;
≪ / RTI > an electrolyte for a sodium-sulfur dioxide secondary cell.
(X is a halogen compound, saturated hydrocabon (R) having C1 to C20, unsaturated hydrocabon (R) having C1 to C20, OR or SR, and n is an integer of 0 to 10) The method according to claim 6,
Wherein the molar ratio of NaX and FeX _n is 2.0: 1.0 to 1.0: 2.0. The method according to claim 6,
Further comprising other sulfur dioxide-based inorganic electrolytes using any one of NaAlCl ₄ , Na ₂ CuCl ₄ , Na ₂ MnCl ₄ , Na ₂ CoCl ₄ , Na ₂ NiCl ₄ , Na ₂ ZnCl ₄ and Na ₂ PdCl ₄ ≪ / RTI > an electrolyte for a sodium-sulfur dioxide secondary battery.

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