KR101309727B1 - Sodium-sulfur rechargeable battery - Google Patents

Abstract

Improved structure of safety tube to ensure the safety of the battery even if the gap between the safety tube and the electrolyte tube is finely managed, the positive electrode container containing sulfur, the negative electrode container containing sodium, the positive electrode container and the negative electrode An electrolyte tube installed between the vessels and selectively transporting only sodium ions, an insulator insulating between the negative electrode container and the positive electrode container, the negative electrode container wrapped between the electrolyte tube and the negative electrode container and selectively blocking the electrolyte tube and the negative electrode container. It includes a safety tube, the safety tube provides a sodium sulfur battery comprising at least one protrusion protruding in the circumferential direction on the outer peripheral surface.

Description

[0001] SODIUM-SULFUR RECHARGEABLE BATTERY [0002]

The present invention relates to a sodium sulfur battery. More specifically, the present invention relates to a sodium sulfur battery having an improved structure of a safety tube.

Generally, a sodium-sulfur battery is developed as a large-capacity power storage battery because of its high energy density, charge / discharge efficiency, self-discharge, and irregular charge / discharge characteristics.

Sodium sulfur batteries use sodium alumina (Na) as the cathode, sulfur (S) as the anode, and beta-alumina ceramics of the solid electrolyte having sodium ion conductivity as the electrolyte. The sodium sulfur battery includes an anode tube enclosing an electrolyte tube and an electrolyte tube. The electrolyte tube has a structure in which a beta-alumina ceramic having a property of passing only sodium ions is formed in a tube shape. The inside of the electrolyte tube is filled with sodium, and sulfur and carbon felt are placed between the electrolyte tube and the positive electrode container. The sodium ion is transferred between the cathode and the anode through the beta alumina, which is an electrolytic tube, to charge and discharge the battery.

In the case of sodium sulfur battery, when the electrolytic tube is broken during operation, the sulfur of the anode flows into the cathode through the breakage portion of the electrolytic tube, and thereby contacts with the sodium of the cathode to cause a rapid chemical reaction.

Sodium and sulfur will produce sodium sulphide upon contact. The sulfide formation reaction is an exothermic reaction in which the enthalpy change is about -380 to -470 KJ / mole at 300 ° C. Therefore, there is a risk that the battery will fire or explode when sulfur in the anode is reacted with a large amount of sodium in the negative electrode.

The sodium sulfur battery is installed inside the electrolyte pipe, and a safety pipe is installed to block the inflow of sulfur when the electrolyte pipe breaks. The safety tube is a metallic material having a large thermal expansion coefficient and maintains a fine gap with the electrolyte tube. Therefore, the safety tube is expanded due to the temperature rise due to the exothermic reaction of sulfur and sodium when the electrolyte tube is broken, and thus is in close contact with the inner surface of the electrolyte tube, thereby preventing further chemical reaction and heat generation.

However, the above-described conventional structure requires a clearance between the inner circumferential surface of the electrolyte tube and the safety tube over the entire inner circumferential surface of the electrolyte tube in order for the safety tube to function properly.

In order to control the gap between the electrolyte tube and the safety tube at regular intervals, accurate numerical measurement and control of the electrolyte tube and the safety tube is required, as well as the construction of a complex facility for accurate expansion during the manufacture of the safety tube.

Therefore, the manufacturing and installation of the safety tube is not easy and the economical efficiency is lowered. Technically, when the safety tube is expanded, contact with the electrolyte tube may occur, thereby increasing the possibility of breakage of the electrolyte tube.

Thus, there is provided a sodium sulfur battery that can easily and simply ensure the safety of the battery.

In addition, the structure of the safety tube is improved to ensure the safety of the battery even if the gap between the safety tube and the electrolyte tube only finely managed to provide a sodium sulfur battery.

To this end, the present sodium sulfur battery is insulated between the positive electrode container containing sulfur, the negative electrode container containing sodium, the electrolyte tube installed between the positive electrode container and the negative electrode container and selectively transferring only sodium ions, and the insulating container between the negative electrode container and the positive electrode container. Insulator to be installed, wrapped between the electrolyte tube and the negative electrode container wrapped around the negative electrode container and includes a safety tube for selectively blocking between the electrolyte tube and the negative electrode container,

The safety tube may include at least one protrusion protruding in the circumferential direction on the outer circumferential surface.

The protrusion may have a structure in which a plurality of protrusions are disposed at intervals along the longitudinal direction of the safety tube.

The protrusion may be integrally formed with the safety tube.

The protrusion may have a curved shape formed in an arc shape.

The safety tube may have an upper end installed on the insulator and extend to a metal collar connected to the negative electrode container, and the protrusion may be formed at the upper end of the safety tube toward the metal collar.

The protrusion may be made of a metal ring installed on the outer peripheral surface of the safety tube.

Thus, according to the present embodiment, by managing only a small portion of the clearance between the safety tube and the electrolyte tube in comparison with the conventional, the manufacturing of the safety tube and the battery assembly process can be made more simply and easily.

In addition, the safety of the battery can be sufficiently secured without increasing the accuracy of the assembly of the safety tube, the electrolyte tube, or the like, and the cost competitiveness of the battery can be lowered.

In addition, it is possible to simplify the manufacturing process and minimize the possibility of breakage of the electrolyte tube, which may occur during manufacturing, by eliminating a conventional complicated process such as safety tube expansion during battery assembly.

1 is a cross-sectional view of a sodium sulfur battery according to an embodiment of the present invention.
2 is a cross-sectional view illustrating a sodium sulfur battery according to another embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It will be apparent to those skilled in the art that the embodiments described below may be modified in various forms without departing from the spirit and scope of the present invention, .

The drawings are schematic and illustrate that they are not drawn to scale. The relative dimensions and ratios of the parts in the figures are shown exaggerated or reduced in size for clarity and convenience in the figures, and any dimensions are merely illustrative and not restrictive.

1 shows a sodium sulfur battery according to this embodiment.

Referring to FIG. 1, the sodium sulfur secondary battery 100 according to the present embodiment includes an electrolyte tube 10 made of beta alumina ceramic, a cathode container 12 positioned inside the electrolyte tube 10 and filled with sodium, and an electrolyte. A positive electrode container 14 located outside the tube 10, an insulator 16 insulating between the negative electrode container and the positive electrode container, the negative electrode container is wrapped between the electrolyte tube and the negative electrode container is installed between the electrolyte tube and the negative electrode container It includes a safety tube 20 to selectively block.

The positive electrode container 14 is disposed outside the electrolyte pipe 10, and a felt collector 18 containing sulfur is filled between the positive electrode container 14 and the electrolyte pipe 10. The felt collector 18 is, for example, carbon felt having pores therein, and sulfur is contained in the pores. The anode container 14 is made of, for example, a cylindrical shape and made of a metal material such as aluminum or stainless steel. In addition, a corrosion resistant layer containing chromium, molybdenum or the like as a main component may be coated on the surface of the positive electrode container 14. The positive electrode container 14 also serves as an external terminal of the positive electrode.

The cathode container 12 may contain sodium, and an inert gas such as nitrogen gas or argon gas may be filled at a predetermined pressure in the inner upper space. The negative electrode container may be made of a metal material such as aluminum, stainless steel, and the like as the positive electrode container 14. The surface of the negative electrode container 12 may be coated with a corrosion resistant layer composed mainly of chromium, molybdenum, or the like. The cathode vessel 12 also serves as an external terminal of the cathode.

In the lower end of the cathode vessel 12, an opening 13 through which the sodium can escape so that sodium filled in the anode vessel 12 can contact the electrolyte tube 10 is formed. Sodium which has passed through the opening 13 is filled between the electrolyte tube 10 and the cathode vessel 12 and comes into contact with the inner wall of the electrolyte tube 10.

The electrolyte tube 10 is made of a beta alumina ceramic capable of passing sodium ions. The electrolyte tube 10 is installed in a tube shape and surrounds the cathode container 12 at a predetermined interval.

An insulator 16 is installed between the negative electrode container 12 and the positive electrode container 14 to prevent a short between the negative electrode and the positive electrode to insulate the negative electrode container 12 from the positive electrode container 14. The insulator 16 is a ring-shaped structure made of alpha alumina ceramic and is bonded to the upper portion of the anode container 14. A ring-shaped metal collar 17 is bonded to an upper end of the insulator 16, and the cathode container 12 is connected to the insulator 16 through the metal collar 17. The insulator 16 is bonded to the inner surface of the electrolyte tube 10 through a glass bonding process, and the upper and lower metal collars 17 and the anode vessel 14 are thermally compressed (TCB; thermal compression bonding), respectively. Joined through the process.

On the other hand, the safety tube 20 is installed to surround the negative electrode container 12 between the electrolyte tube 10 and the negative electrode container (12). The safety tube 20 is a tubular structure having an open top, and is disposed while maintaining a gap between the cathode container 12 and the electrolyte tube 10. The sodium of the negative electrode container 12 is discharged through the opening 13 of the lower portion is introduced between the safety tube 20 and the negative electrode container 12, flows through the open upper end of the safety tube 20 safety tube ( 20) flows in between the electrolyte tube (10).

Wherein the safety tube 20 is expanded to the outside by the high heat generated by the exothermic reaction of sulfur and sodium flow introduced when the electrolyte tube 10 breaks so as to block between the electrolyte tube 10 and the cathode container 12. do.

To this end, the safety tube 20 of the present embodiment has a structure in which a plurality of protrusions 22 protruding outward in the circumferential direction are formed on the outer circumferential surface. The protrusions 22 are arranged along the longitudinal direction of the safety tube 20 a plurality of intervals. In FIG. 1, the distance L between the protrusions 22 is an allowable reaction amount of sodium when the electrolyte tube breaks, the thermal expansion coefficient of the safety tube and the electrolyte tube, the size and shape of the safety tube and the electrolyte tube, or the inner surface of the electrolyte tube. It may vary depending on the illuminance or the driving temperature of the battery, and is not particularly limited.

The protrusion 22 has an arc-shaped cross-sectional structure and is integrally formed with the safety tube 20.

Accordingly, when the sulfur and sodium introduced when the electrolyte tube 10 is damaged react with the safety tube 20, the protruding portion 22 formed in the safety tube 20 is in close contact with the inner surface of the electrolyte tube 10. Therefore, the additional supply of sodium is blocked by the protrusion 22 to stop the chemical reaction of sodium and sulfur.

As such, the battery operates the safety tube 20 by finely controlling a gap between the electrolyte tube 10 and only a part of the safety tube 20, that is, the protrusion 22 protruding outward. It is possible to ensure the safety of the battery.

The protruding portion 22 has a ring shape to produce a safety tube 20 having a predetermined clearance gap between the electrolyte tube 10 and a predetermined radius of curvature from the inside to the outside along the circumferential direction of the safety tube 20. It is formed by plastic deformation. In this case, the protrusion degree of the protrusion part 22 must be precisely calculated because it forms a gap d between the electrolyte tube 10. In this embodiment, after the plastic deformation of the safety tube 20 as described above, the strain stress is removed so that the gap between the outer end of the protrusion 22 and the electrolyte tube 10 in a state where the protrusion 22 is recovered by elasticity. The protrusion 22 is formed to a size corresponding to the predetermined interval.

For example, the safety tube 20 may be formed such that the clearance gap d between the tip of the protrusion 22 and the electrolyte tube 10 has a value in the range of 0.01 to 0.2 mm. In this case, the remaining part of the safety tube 20 except for the protrusion 22 may be formed only within the clearance gap D between the electrolyte tube 10 and approximately 2 mm. Therefore, when manufacturing and installing the safety tube 20, it is possible to reduce the effort to finely control the gap between the electrolyte tube 10 over the safety tube 20 front.

Here, the gap gap d between the tip of the protrusion 22 and the electrolyte tube 10 or the gap gap D between the safety tube 20 and the electrolyte tube 10 may allow sodium when the electrolyte tube 10 is damaged. Reaction amount, thermal expansion coefficient of safety tube 20 and electrolyte tube 10, size and shape of safety tube 20 and electrolyte tube 10, internal surface roughness of electrolyte tube 10, or driving temperature of battery It may vary depending on the like and is not particularly limited.

Looking at the operation of the battery according to the present embodiment, when the electrolyte tube 10 is damaged during the operation of the battery, sulfur is introduced into the electrolyte tube 10 through the broken portion of the electrolyte tube 10.

Sulfur introduced into the electrolyte tube 10 causes an exothermic reaction with sodium in the gap between the electrolyte tube 10 and the safety tube 20. As a result, the temperature of the electrolyte tube 10 is momentarily increased. Due to the instantaneous temperature increase in the location, the safety tube 20 expands to the outside and the protrusion 22 formed in the safety tube 20 expands and moves to the electrolyte tube 10 to be in close contact with the electrolyte tube 10. . Therefore, the protrusion 22 is in close contact with the electrolyte tube 10 to locally seal the damaged portion of the electrolyte tube 10. As the protrusion 22 of the safety tube 20 seals the electrolyte tube 10, sodium is not additionally introduced into the damaged portion of the electrolyte tube 10, and the exothermic reaction with the sulfur is in a locally enclosed space. Limited to the amount of sodium.

On the other hand, Figure 2 shows a battery with a safety tube of another embodiment.

In the present embodiment, except for the structure of the safety tube 30 of the battery 100, the rest of the battery is the same as the other embodiments mentioned above. The same reference numerals are used for the same configuration, and detailed description thereof will be omitted.

As shown, the safety tube 30 has an upper end installed on the insulator and extends to the metal collar 17 connected to the negative electrode container 12, and the metal collar 17 on the upper end of the safety tube 30. The protrusion part 32 which protruded outward toward () is provided.

In this embodiment, the safety tube 30 is in close contact with the metal collar 17 rather than the electrolyte tube 10 to block the inflow of sodium.

Here, the protrusion 32 is made of a metal ring 34 is installed on the outer peripheral surface of the safety tube (30). In addition to the metal ring 34 structure, the protrusion 32 may be integrally formed on the outer circumferential surface of the safety tube 30.

The metal ring 34 is a circular ring structure, made of a metal material. The metal ring 34 may be made of a material having a coefficient of thermal expansion relatively larger than that of the metal collar 17.

The metal ring 34 is not particularly limited in form as long as it can be in close contact with the metal collar 17 during expansion.

The safety tube 30 extends upwards to a position facing the metal collar 17 bonded to the upper end of the insulator 16. The metal ring 34 is installed along the upper outer circumferential surface of the safety tube 30 facing the metal collar 17.

The metal ring 34 has a uniform thickness. Thus, the battery finely adjusts the clearance gap d between the metal ring 34 and the metal collar 17 regardless of the safety tube 30 to ensure safety of the battery by operating the safety tube 30 normally. You can do it.

For example, the metal ring 34 may be formed such that the gap d between the outer end and the electrolyte tube 10 has a value ranging from 0.01 mm to 0.2 mm. In this case, the remaining portion of the safety tube 30, except for the metal ring 34, the clearance gap (D) between the electrolyte tube 10 and only need to be formed within approximately 2mm. Therefore, when manufacturing and installing the safety tube 30, it is possible to reduce the effort to finely control the gap with the electrolyte tube 10 over the front of the safety tube 30.

The gap gap d between the tip of the metal ring 34 and the electrolyte tube 10 or the gap gap D between the safety tube 30 and the electrolyte tube 10 is an allowable reaction amount of sodium when the electrolyte tube breaks. The thermal expansion coefficient of the metal ring and the metal color may vary depending on the driving temperature of the battery, and the like is not particularly limited.

Here, the gap D between the safety tube 30 and the electrolyte tube 10 determines the total amount of sodium that reacts with sulfur introduced from the anode when the electrolyte tube 10 is damaged. In this embodiment, the size of the safety tube 30, that is, the clearance gap D between the safety tube 30 and the electrolyte tube 10, does not exceed the dangerous level of total calorific value with sulfur due to the total amount of sodium. It is determined in the range. The total calorific value is the amount of sodium that is isolated between the safety tube 30 and the electrolyte tube 10 after the addition of sodium is blocked by the metal ring 34 when the electrolyte tube 10 is broken and sulfur introduced into the cathode; It means the amount of heat generated when all reactions. Therefore, the safety tube 30 determines the clearance gap between the safety tube 30 and the electrolyte tube 10 so that the total heat generation amount does not exceed the dangerous level.

Looking at the operation of the battery according to the present embodiment, when the electrolyte tube 10 is damaged during battery operation, the temperature of the battery rises, the safety tube 30 and the metal ring 34 installed in the safety tube 30 to the outside Finally, as the metal ring 34 contacts the inner circumferential surface of the metal collar 17, the metal ring 34 blocks the path in which sodium is introduced between the safety tube 30 and the electrolyte tube 10.

Here, the metal collar 17 has a large thermal expansion coefficient as a metal material, but the amount of thermal deformation is limited by the insulator 16 which is a ceramic material bonded thereto. As a result, the metal ring 34 is further inflated relative to the metal collar 17 to be in close contact with the metal collar 17.

As the safety tube 30 is in close contact with the metal collar 17 via the metal ring 34, the safety tube 30 is closed between the safety tube 30 and the electrolyte tube 10. The addition of sodium into the electrolyte tube 10 is blocked so that the exothermic reaction with sulfur is limited to the amount of sodium in the sealed space between the safety tube 30 and the electrolyte tube 10. Therefore, the safety of the battery is secured.

In general, since the processing tolerance of metal is much smaller than the processing tolerance of ceramic, the present battery has a simple structure as described above, even without a complicated process such as measuring the inner diameter of the electrolyte tube 10 or expanding the safety tube 30 as in the related art. It is possible to easily secure the safety through.

While the illustrative embodiments of the present invention have been shown and described, various modifications and alternative embodiments may be made by those skilled in the art. Such variations and other embodiments will be considered and included in the appended claims, all without departing from the true spirit and scope of the invention.

10: Electrolyte tube 12: Negative electrode container
13: opening 14: positive electrode container
16: insulator 17: metal color
18: felt collector 20,30: safety tube
22,32: protrusion 34: metal ring

Claims (6)

A positive electrode container containing sulfur, a negative electrode container containing sodium, an electrolyte tube installed between the positive electrode container and the negative electrode container to selectively move only sodium ions, an insulator insulating the negative electrode container and the positive electrode container, and wrapping the negative electrode container A safety tube installed between the electrolyte tube and the negative electrode container and selectively blocking the electrolyte tube and the negative electrode container, wherein the safety tube includes at least one protrusion projecting along the circumferential direction on an outer circumferential surface thereof;
The safety tube of the sodium sulfur battery structure of the structure is formed in the upper end is extended to the metal collar of the upper part of the insulator, the protruding portion at the top of the safety tube toward the metal collar. The method of claim 1,
The protrusion is a sodium sulfur battery of the structure arranged in a plurality of intervals along the longitudinal direction of the safety tube. 3. The method according to claim 1 or 2,
The protrusion is a sodium sulfur battery of a curved structure in the form of an arc. The method of claim 3, wherein
The protruding portion is a sodium sulfur battery formed integrally with the safety tube. delete The method of claim 1,
The protrusion is a sodium sulfur battery consisting of a metal ring installed on the outer peripheral surface of the safety tube.

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