KR101353602B1 - sodium sulfur battery - Google Patents

Abstract

A sodium-sulfur cell is provided. According to the present invention, there is provided a sodium-sulfur battery having a structure in which sodium as a negative electrode active material and sulfur as a positive electrode active material are separated and stored as a solid electrolyte having a function of selectively permeating sodium ions. Anode container for receiving the; A cartridge containing molten metal sodium; A solid electrolyte tube accommodating the cartridge therein and selectively transmitting sodium ions; And a reactant charged between the cartridge and the solid electrolyte tube and reacting with the heat of reaction generated by the reaction between sodium and sulfur to control the amount of sodium reacted with sulfur.

Description

Sodium sulfur battery

The present invention relates to a sodium-sulfur cell, and more particularly, by blocking the supply of sodium when a mass reaction between sodium (Na) and sulfur (S) proceeds by damage to the beta alumina tube during operation of the sodium-sulfur cell. Since no further reaction proceeds, the present invention relates to a sodium-sulfur battery having excellent use safety.

In recent years, sodium-sulfur batteries have been researched to increase the demand for electric power and to utilize the active materials in a high manner, and to have high efficiency of charge and discharge reactions.

Such a sodium-sulfur battery has a structure in which sodium, which is an anode active material, and sulfur, which is a cathode active material, are isolated and stored as? -Alumina, which is a solid electrolyte having a function of selectively permeating sodium ions, Temperature sealed secondary battery operated at a high temperature.

The structure of such a sodium-sulfur battery is, for example, a cylindrical cathode container containing molten sulfur (S) impregnated in an anode conductive material 3 such as carbon felt. (One); A cartridge 5 containing molten metal sodium (Na); A cylindrical solid electrolyte tube 7 containing the cartridge 5 and having a function of selectively permeating sodium ions and made of β-alumina; A cylindrical safety tube 9 is provided at regular intervals from the cartridge 5 and the solid electrolyte tube 7 in the interval between the cartridge 5 and the solid electrolyte tube 7.

In a sodium-sulfur battery having such a structure, during discharge, sodium (Na) supplied from the small hole (6) of the cartridge (5) upwards from the gap between the safety tube (9) and the cartridge (5). After moving, the upper end of the safety tube 9 is crossed, and the lower portion is moved downward in the gap between the safety tube 9 and the solid electrolyte tube 7, and the solid electrolyte tube 7 is made of sodium ions. It penetrates, reacts with sulfur in the anode vessel 1 and electrons that can pass through an external circuit and produces sodium polysulfide. In charging, the reaction of generating sodium and sulfur occurs opposite to the discharge.

The safety tube 9 is made of an aluminum alloy, and is inserted between the cartridge 5 and the solid electrolyte tube 7, and when the solid electrolyte tube 7 is broken, sodium (Na) and sulfur ( The safety tube 9 is expanded by the heat of reaction between S), and the gap between the solid electrolyte tube 7 and the safety tube 9 is reduced to limit the amount of sodium participating in the reaction.

However, when the solid electrolyte tube 7 is broken and a large amount of reaction between sodium and sulfur proceeds, sodium is continuously supplied into the gap between the solid electrolyte tube 7 and the safety tube 9, so that the sodium Further reaction proceeds, and thus there is a problem in that the safety of the battery is lowered due to the explosion of the battery due to the temperature increase inside the battery.

In addition, in order to insert the safety tube 9 into the solid electrolyte tube 7, the inner diameter of the solid electrolyte tube 7 is measured, and the safety tube (7) is matched to the inner diameter of the solid electrolyte tube 7. 9) the process of precisely plastically deforming to press the cartridge 5 to maintain a constant distance to the cartridge 5 is required, thereby increasing the manufacturing process and increasing the manufacturing cost, and as much as the space occupied by the safety tube. There was also a problem that the energy capacity is reduced because the space for filling sodium is reduced.

In the present invention, when a large amount of reaction between sodium (Na) and sulfur (S) proceeds due to damage of a solid electrolyte tube during operation of a sodium-sulfur battery, additional reaction does not proceed by blocking the supply of sodium. It is intended to provide a sulfur battery.

According to an embodiment of the present invention, a sodium-sulfur battery having a structure in which sodium as a negative electrode active material and sulfur as a positive electrode active material are separated and stored as a solid electrolyte having a function of selectively permeating sodium ions,

A positive electrode container containing molten sulfur impregnated in the positive electrode conductive material; A cartridge containing molten metal sodium; A solid electrolyte tube accommodating the cartridge therein and selectively transmitting sodium ions; And a reactant charged between the cartridge and the solid electrolyte tube and reacting with the heat of reaction generated by the reaction between sodium and sulfur to control the amount of sodium reacted with sulfur.

The reactant may be made of aluminum powder.

The aluminum powder may be formed in a spherical shape having a mean particle size of a certain size.

The surface of the reactant may be heat treated to form a thin oxide film.

Heat treatment of the reactant surface may be performed in an oxidizing atmosphere of 300 ~ 500 ℃.

The average particle diameter of the reactant may be a size in the range of 40 ~ 80㎛.

The distance between the cartridge and the solid electrolyte tube may be at least 0.5 mm.

According to this embodiment, when a large amount of reaction between sodium (Na) and sulfur (S) proceeds due to damage to the solid electrolyte tube during operation of the sodium-sulfur battery, by blocking the supply of sodium, further reaction does not proceed, so the safety of use Is excellent,

In addition, safety design is possible regardless of the manufacturing tolerance of the solid electrolyte tube, and can be utilized to fill the space occupied by the existing safety tube, so it has the effect of increasing the energy capacity, and is also safe in the solid electrolyte tube. Since the precision plastic deformation process for inserting the tube is removed, the manufacturing process can be reduced and the manufacturing cost can be reduced.

1 is a schematic configuration diagram of a sodium-sulfur battery according to an embodiment of the present invention.
2 is a schematic configuration diagram of a sodium-sulfur battery according to the prior art.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

1 is a schematic configuration diagram of a sodium-sulfur battery according to an embodiment of the present invention.

Referring to FIG. 1, a sodium-sulfur battery according to an embodiment of the present invention includes a cylindrical anode container 101 containing molten sulfur S impregnated in a cathode conductive material 103 such as carbon felt; A cartridge 105 containing molten metal sodium (Na);

A cylindrical solid electrolyte tube 107 which accommodates the cartridge 105 therein and selectively transmits sodium ions; And

And a reactant 109 filled between the cartridge 105 and the solid electrolyte tube 107 and reacting with the heat of reaction generated by the reaction between sodium and sulfur to control the amount of sodium reacted with sulfur. .

The reactant 109 may be made of, for example, aluminum powder so that the amount of sodium supplied can be easily adjusted according to the degree of reaction between sodium and sulfur.

The aluminum powder may be formed in a spherical shape having a mean particle size of a certain size.

In addition, the surface of the reactant 109 may be heat treated in an oxidizing atmosphere at 300 to 500 ° C. to form a thin oxide film, for example, in order to improve wettability to sodium (described in detail below with reference to Table 1). have.

Here, the heat treatment of the surface of the reactant 109 at 300 to 500 ° C. is not easy to form a film on the surface of the reactant 109 at a heat treatment of 300 ° C. or lower, and the reactant 109 at a heat treatment of 500 ° C. or more. Is because aluminum is softened to form a uniform film.

In addition, the average particle diameter of the reactant 109 may be, for example, a size in the range of 40 to 80 μm so as not to disturb the supply of sodium during battery operation and to limit the supply of sodium in case of breakage of the solid electrolyte tube 107. Can be.

Here, the average particle diameter of the aluminum spherical powder, which is the reactant 109, is set to a size within the range of 40 to 80 μm. When the average particle diameter of the reactant 109 is smaller than 40 μm, the supply of sodium (Na) is interrupted and filled. This is because the discharge characteristics are not good, and if the particle size of the reactant 109 is larger than 80 μm, the supply of sodium is not limited when the solid electrolyte tube 107 breaks.

In addition, although the gap between the cartridge 105 and the solid electrolyte 107 tube is smaller in order to maximize the content of the sodium active material, it is advantageous, but the filling of the aluminum spherical powder, which is the reactant 109, and the hotness of the cartridge 105. When considering expansion and the like, for example, it may be at least 0.5mm or more.

 The method of aligning the cartridge 105 with the center of the battery is not particularly limited, but a plurality of studs (not shown) are installed on the outer circumferential surface of the bottom of the cartridge 105 to move the cartridge 105 to the center of the forward direction. Can be sorted on

As described above, since the sodium-sulfur battery of the present invention has a structure for filling aluminum spherical powder, which is the reactant 109, between the cartridge 105 and the solid electrolyte tube 107, the solid electrolyte tube 107 When this is broken, heat (S) flows into the cathode and reacts with sodium (Na) supplied from the small hole (106) of the cartridge (105) to generate heat of reaction, which causes the surrounding aluminum spherical powder to expand. While the pores between the aluminum spherical powders are reduced, the supply of sodium (Na) is reduced as the pores are reduced.

In particular, when a large amount of reaction between sodium and sulfur proceeds, more heat of reaction is generated between sulfur and sodium, and the temperature rises rapidly by this much heat of reaction, and the aluminum spherical powder melts due to such a rapid temperature rise.

As such, when the aluminum spherical powder is melted, the voids between the aluminum spherical powders are eliminated, and thus, the supply of sodium (Na) is blocked, thereby preventing further reaction between sodium and sulfur.

Accordingly, in the structure of filling the aluminum spherical powder, which is the reactant, between the cartridge and the solid electrolyte tube as in the present invention, a safety design is possible regardless of the manufacturing tolerances of the solid electrolyte tube, and the safety tube in the related art. Since the space occupied by the safety tube can be used to fill the sodium, there is an effect of increasing the energy capacity, and since the precision plastic deformation process of the safety tube is removed, the manufacturing process is reduced and the manufacturing cost is reduced. Can be.

[Experimental Method]

Filling density: Put a predetermined aluminum spherical powder in a 100ml measuring cylinder and vibrate to calculate the filling density

Wetability Evaluation for Sodium (Na): Filled aluminum spherical powder inside an alumina crucible (depth 100 mm) and heated with a heater installed inside a glove box, and a predetermined liquid sodium (Na) on the filled aluminum spherical powder. After inputting, solidify after a certain time, cut the cross section of the solidified specimen and measure the depth of penetration of sodium (Na) to compare the wettability. Compare the supply performance of sodium (Na) in the same way.

Charge / discharge test: An experiment is performed to artificially break a solid electrolyte tube by applying a 7 V load to the manufactured single cell. At this time, measure the surface temperature of the unit cell. Compare battery safety with temperature rise.

[Table 1]

From Table 1, when comparing Examples 1 to 3 with Comparative Examples 1 to 4, in Examples 1 to 3, the particle size (average particle diameter) of the aluminum spherical powder was 40 to 80 µm, and the heat treatment temperature of aluminum was 300, In case of 350 ℃, the battery temperature is 362 ~ 365 ℃, which is the lowest, but in Comparative Examples 1-4, when the aluminum spherical powders have particle sizes of 10, 50, and 150 µm and the heat treatment temperatures of aluminum are 200, 350 and 600 ℃, As 455, 450, 460, and 440 degreeC, it turns out that a battery temperature is higher than the case of Examples 1-3.

In addition, under the above conditions, in Examples 1 to 3, the packing densities were 2.35, 2.37, and 2.42 g / cm ³ , whereas in Comparative Examples 1 to 4, 2.43, 1.59, 2.91, and 1.21 g / cm ³ were used. It can be seen that it is slightly smaller than 3.

Under the above conditions, in Examples 1 to 3, sodium (Na) penetration depths were 95, 97, and 96 mm, whereas in Comparative Examples 1 to 4, sodium (Na) penetration depths were 10, 6, 25, and 95 mm. It is shorter than ~ 3.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Of course.

101: positive electrode container 103: conductive material for positive electrode
105: cartridge 107: solid electrolyte tube
109: reactant

Claims (7)

A sodium-sulfur battery having a structure in which sodium as a negative electrode active material and sulfur as a positive electrode active material are separated and stored as a solid electrolyte having a function of selectively permeating sodium ions,
A positive electrode container containing molten sulfur impregnated in the positive electrode conductive material;
A cartridge containing molten metal sodium;
A solid electrolyte tube accommodating the cartridge therein and selectively transmitting sodium ions; And
A reactant charged between the cartridge and the solid electrolyte tube and reacting with the heat of reaction generated by the reaction between sodium and sulfur to control the amount of sodium reacted with sulfur
/ RTI >
A surface of the reactant is heat-treated to form a thin oxide film. The method of claim 1,
The reactant is a sodium-sulfur battery consisting of aluminum powder. 3. The method of claim 2,
The aluminum powder is a sodium-sulfur battery made of a spherical shape having a constant average particle diameter. delete The method of claim 1,
Sodium-sulfur battery heat treatment of the reactant surface is made in an oxidizing atmosphere of 300 ~ 500 ℃. In the third aspect,
An average particle diameter of the reactant is a sodium-sulfur battery having a size in the range of 40 ~ 80㎛. In the first aspect,
The gap between the cartridge and the solid electrolyte tube is at least 0.5 mm or more sodium-sulfur battery.

Images