JP2001338624A - Anode container for sodium-sulfur cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anode container for a sodium-sulfur cell which makes it possible to delay a damage of joining part or a peripheral area for a pipe and a bottom cover, which is caused and generated by an active material entering into a gap between a pipe and a bottom cover constituting an anode container, and a stress acting on the gap. SOLUTION: The anode container for the sodium-sulfur cell is constructed by joining a metal pipe 15 structuring a trunk of a container to a bottom cover 13. The anode container has a structure to delay an active material entering into a gap of an insertion-coupling part of the pipe 15 with the bottom cover 13 in reaching the joining part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an anode container used for containing sulfur and sodium polysulfide in a sodium-sulfur battery.

[0002]

2. Description of the Related Art A sodium-sulfur battery has molten metal sodium as a cathode active material on one side and molten sulfur as an anode active material on the other side, and both have selective permeability to sodium ions. This is a high-temperature secondary battery operated at 300 to 350 ° C. isolated by a β-alumina solid electrolyte.

[0003] The structure of such a sodium-sulfur battery is, for example, as shown in FIG. 3, a bottomed cylindrical anode container 1 containing molten sulfur S impregnated in carbon felt or the like.
A cartridge (sodium protective tube) 6 containing molten metal sodium Na, a bottomed cylindrical solid electrolyte tube 5 containing the cartridge 6 therein and having a function of selectively transmitting sodium ions Na ^+. And a bottomed cylindrical partition tube 11 disposed at a predetermined distance from the cartridge 6 and the solid electrolyte tube 5 in a gap between the cartridge 6 and the solid electrolyte tube 5.

The solid electrolyte tube 5 is connected to the anode container 1 via an α-alumina insulating ring 4 and an anode cylindrical metal fitting 3 which are glass-joined to the open end thereof. A cathode fitting 8 is joined to the upper end surface of the insulating ring 4 by heat and pressure, and a cathode lid 9 is fixed to the cathode fitting 8 by welding. An anode terminal 2 and a cathode terminal 10 are provided on the outer peripheral upper portion of the anode container 1 and the upper surface of the cathode lid 9, respectively. An inert gas G such as nitrogen gas or argon gas is sealed in the upper space of the cartridge 6 at a predetermined pressure, and the inert gas G causes sodium Na in the cartridge 6 to pass through a small hole 7 provided at the bottom of the cartridge. Pressurized in the outflow direction.

In the sodium-sulfur battery having such a structure, the sodium Na supplied from the small hole 7 of the cartridge 6 at the time of discharging moves upward in the gap between the partition tube 11 and the cartridge 6, 11, it moves downward in the gap between the partition tube 11 and the solid electrolyte tube 5, further penetrates the solid electrolyte tube 5 as sodium ions, and transmits sulfur S inside the anode container 1 and the outside. Reacts with electrons passing through the circuit to produce sodium polysulfide. At the time of charging, a reaction of forming sodium and sulfur occurs in reverse to discharging.

[0006] The anode container used in the sodium-sulfur battery includes a pipe forming a cylindrical body and a bottom cover. A conventional anode container forms a coating having corrosion resistance against an anode active material such as a chromium iron alloy by spraying on the inner surface of a metal pipe such as aluminum or an aluminum alloy, and then forms one end of the opening of the pipe. Was manufactured by joining the bottom lid to the bottom lid by electron beam welding. In addition,
At the time of electron beam welding, as shown in FIG. 4, the electron beam is inserted into the opening of the opening end of the pipe 15 in the bottom cover 13 in order to prevent the electron beam from penetrating through the welded portion and causing a welding defect. Backup unit 13a.

In addition, spraying the inner surface of the pipe 15 as described above before attaching the bottom cover 13 is performed by spraying the pipe whose one end is sealed by the bottom cover 13.
This is because heat at the time of thermal spraying cannot be released to the outside of the pipe, and the heat causes deformation and melting of the pipe.

[0008]

The conventional anode container as described above is, as shown in FIG.
There is a gap 11 at the fitting portion between the
The active material enters 1. And the gap 11 of this fitting portion
When the corrosive active material that has entered the pipe reaches the joint (weld) between the pipe 15 and the bottom lid 13, corrosion due to the active material, changes in internal pressure due to charge / discharge of the battery, and stress generated by temperature rise / fall are caused. , Stress corrosion of the joint occurs. Due to this stress corrosion, in the conventional anode container, in a relatively short time, the end of the pipe 15 near the fitting portion is deformed outwardly of the pipe, and a crack is formed in the welded portion or in the vicinity thereof, and the active material is removed. There was a problem of leakage.

The present invention has been made in view of such a conventional situation, and an object of the present invention is to provide an active material that has penetrated into a gap between a fitting part of a pipe and a bottom lid constituting an anode container. Another object of the present invention is to provide an anode container for a sodium-sulfur battery that can delay damage to a joint between a pipe and a bottom cover or a peripheral portion thereof caused by stress acting on the gap.

[0010]

According to the present invention, there is provided an anode container for a sodium-sulfur battery in which a bottom cover is joined to a metal pipe constituting a body of the container, wherein the pipe and the bottom cover are provided. And an anode container for a sodium-sulfur battery, characterized in that the anode container has a structure that delays the arrival of the active material, which has entered the gap between the fitting portions, to the joining portion.

[0011]

Embodiments of the present invention will be described with reference to the drawings. As described above, in the anode container for a sodium-sulfur battery of the present invention, the active material of the battery that has entered the gap between the fitting portion between the metal pipe and the bottom lid constituting the body of the container reaches the junction. It is characterized by having a structure that delays the execution. By delaying the corrosive active material that has entered the gap between the fitting portion between the metal pipe and the bottom lid to reach the junction between the metal pipe and the bottom lid joined by welding or the like, The life of the container can be extended by delaying the progress of stress corrosion of the joint.

FIG. 1 is a partial sectional view showing an anode container for a sodium-sulfur battery according to an embodiment of the present invention.
In this anode container, a coating (not shown) having corrosion resistance to an anode active material such as a chromium iron alloy is formed on the inner surface of a metal pipe 15 constituting the body of the anode container by thermal spraying or the like, and then formed. A bottom cover 13 having a backup portion 13a inserted into the opening at the opening end and a jacket 13b covering the outer periphery of the pipe 15 at the opening end is fitted into one opening end of the pipe 15. The container is formed by joining the pipe 15 and the outer cover 13b of the bottom lid by welding or the like.

In the present embodiment, the outer cover 13 b covering the outer periphery of the pipe at the open end is provided on the bottom cover 13, and the outer cover 13 b is joined to the pipe 15, so that the fitting portion is formed. It is difficult for the active material that has penetrated into the gap to reach the joint, so that the corrosion of the joint by the active material is delayed and long-term use is possible.

FIG. 2 is a partial sectional view showing an anode container for a sodium-sulfur battery according to another embodiment of the present invention. In this anode container, a coating (not shown) having corrosion resistance to an anode active material such as a chromium iron alloy is formed on the inner surface of a metal pipe 15 constituting the body of the anode container by thermal spraying or the like, and then formed. A screw portion 15 formed complementary to the inner peripheral surface of one open end of the pipe 15 and the outer peripheral surface of the bottom cover 13
Both are screwed together at a and 13c. Further, the container is formed by joining the pipe 15 and the bottom lid 13 by welding or the like at a position further from the outside of the anode container than the formation position of the screw portion.

In the present embodiment, the pipe 15 and the bottom cover 13 are not only joined by welding or the like as described above, but also the pipe 15 and the bottom cover 13 are located at a position closer to the inside of the anode container than the joint portion. The screwing improves the integration of the two and makes it difficult for the active material that has entered the gap between the fittings to reach the joint, delaying the corrosion of the joint by the active material and enabling long-term use. Become.

[0016]

EXAMPLES Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

(Example 1) A coating made of a chromium iron alloy was formed on the inner surface of a pipe made of an aluminum alloy having an outer diameter of 90 mm and a thickness of 2 mm by plasma spraying. A bottom cover having a backup portion inserted into the opening and a jacket covering the outer periphery of the pipe at the end of the opening is fitted, and the pipe and the jacket of the bottom cover are welded, as shown in FIG. An anode container was obtained. Using this anode container, a sodium-sulfur single cell was produced, and a durability test was performed. In the test, continuous energization was performed under the conditions of temperature acceleration and cycle acceleration, and during this period, the temperature was raised and lowered every two months (40
0 ° C. →→ 30 ° C.). The average test temperature is 4
The temperature was set to 00 ° C. Table 1 shows the test results.

(Example 2) A coating made of a chromium iron alloy is formed on the inner surface of a pipe made of an aluminum alloy having an outer diameter of 90 mm and a thickness of 2 mm by plasma spraying, and then the inner peripheral surface of one opening end of the pipe is previously formed. Both were screwed together with a screw portion formed complementary to the outer peripheral surface of the bottom lid. Furthermore,
The pipe and the bottom lid were welded at a position outside the anode container relative to the formation position of the screw portion to obtain an anode container as shown in FIG. Sodium-
A sulfur single cell was manufactured, and a durability test was performed in the same manner as in Example 1. Table 1 shows the test results.

Comparative Example A chromium-iron alloy corrosion-resistant coating was formed on the inner surface of a pipe made of an aluminum alloy having an outer diameter of 90 mm and a thickness of 2 mm by plasma spraying. A bottom cover provided with a backup portion inserted into the opening was fitted and welded to obtain an anode container as shown in FIG. Using this anode container, a sodium-sulfur single cell was produced, and a durability test was performed in the same manner as in Example 1. Table 1 shows the test results.

[0020]

[Table 1]

As shown in Table 1, in the unit cell of the comparative example manufactured using the anode container having the conventional structure, when the test period exceeds 1.5 years, the leakage of the active material from the anode container is observed. became. In contrast, the cells of Examples 1 and 2 produced using the anode container according to the present invention showed no leakage of the active material from the anode container even if the test period exceeded two years, Even after disassembly observation of the cell after the passage of years,
No outward deformation of the bottom of the anode vessel and no cracks in the weld and its vicinity were observed.

[0022]

As described above, when a sodium-sulfur battery is manufactured using the anode container of the present invention, the active material that has entered the gap between the fitting part of the pipe and the bottom lid constituting the anode container includes: Damage to the joint between the pipe and the bottom cover or the peripheral portion caused by the stress acting on the gap can be delayed, and the life and reliability of the battery are improved.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing an anode container for a sodium-sulfur battery according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view illustrating an anode container for a sodium-sulfur battery according to another embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a general structure of a sodium-sulfur battery.

FIG. 4 is a partial cross-sectional view showing a conventional anode container for a sodium-sulfur battery.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Anode container, 2 ... Anode side terminal, 3 ... Anode cylindrical fitting, 4
... insulating ring, 5 ... solid electrolyte tube, 6 ... cartridge,
7 ... Small hole, 8 ... Cathode fitting, 9 ... Cathode cover, 10 ... Cathode side terminal, 11 ... Gap of fitting part, 13 ... Bottom cover, 13a ... Back-up part, 13b ... Cover part, 13c ... Screw part (bottom) 15 ... pipe, 15a ... threaded part (pipe side).

Continued on front page F-term (reference) 5H011 AA02 AA17 CC06 DD17 FF03 JJ04 5H029 AJ13 AJ15 AK05 AL13 AM15 BJ02 CJ06 CJ21 DJ02

Claims (3)

[Claims] An anode container for a sodium-sulfur battery in which a bottom cover is joined to a metal pipe constituting a body of the container, wherein the anode container has entered a gap between a fitting portion between the pipe and the bottom cover. An anode container for a sodium-sulfur battery, having a structure for delaying the arrival of an active material to a junction. 2. A back-up portion inserted into the opening of one of the open ends of the pipe after forming a coating having corrosion resistance to the anode active material on the inner surface of the metal pipe. 2. The anode container for a sodium-sulfur battery according to claim 1, wherein a bottom lid having a jacket covering the outer periphery of the pipe at the opening end is fitted, and the pipe and the jacket are joined. 3. After forming a coating having corrosion resistance to the anode active material on the inner surface of the metal pipe, the inner peripheral surface of one open end of the pipe and the outer peripheral surface of the bottom cover are complementarily formed. 2. The sodium-ion according to claim 1, wherein the two screws are screwed together with the formed screw portion, and the pipe and the bottom lid are joined at a position from the outside of the anode container to a position where the screw portion is formed. Anode container for sulfur batteries.