JP2000090967A - Joint structure of insulation ring and positive electrode cylindrical fitting for sodium-sulfur battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of damages of the jointed part between an insulation ring and a positive electrode cylindrical fitting by improving the strength reliability of that part against a load caused by a thermal contraction difference between a solid electrolyte tube and a positive electrode vessel at the time of a battery temperature drop. SOLUTION: An insulation ring 4 is jointed to the open end of solid electrolyte tube 5, and a positive electrode cylindrical fitting 3 having a cylindrical part 3a and a flange part 3b bulged inward from the lower end thereof is thermocompression jointed to the insulation ring 4 so that the upper surface of the flange part 3b is jointed to the lower edge face of the insulation ring 4. Regarding the jointed structure of the insulation ring 4 and the positive electrode cylindrical fitting of a sodium-sulfur battery so constructed, the value C of clearance 13 between the internal circumferential surface of the cylindrical part 3a of the positive electrode cylindrical fitting 3 and the external circumferential surface of the insulation ring 4 is 0.15 mm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint structure between an insulating ring and an anode cylindrical metal fitting in a sodium-sulfur battery, and more particularly, to a thermal contraction and expansion difference between a solid electrolyte tube and an anode container at the time of battery temperature rise and fall. The present invention relates to a joining structure capable of improving the strength reliability of a joining portion between an insulating ring and an anode cylindrical member with respect to a load.

[0002]

2. Description of the Related Art A sodium-sulfur battery is provided with 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 includes, as shown in FIG. 2, for example, a cylindrical anode container 1 containing molten sulfur S impregnated in carbon felt or the like;
A cartridge (sodium protective tube) 6 for containing molten sodium metal sodium, a bottomed cylindrical solid electrolyte tube 5 containing the cartridge 6 therein and having a function of selectively transmitting sodium ions Na ⁺ , In the gap between the solid electrolyte tube 6 and the solid electrolyte tube 5, the cartridge 6 and the solid electrolyte tube 5 are each provided with a bottomed cylindrical partition tube 11 arranged at a predetermined interval from 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 glass-joined to the open end thereof. A cathode metal 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 metal fitting 8 by welding. An anode-side terminal 2 and a cathode-side 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. In the upper space of the cartridge 6, an inert gas G such as nitrogen gas or argon gas is sealed 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, at the time of discharge, sodium Na supplied from the small hole 7 of the cartridge 6 moves upward in the gap between the partition tube 11 and the cartridge 6, After passing over the upper end, the solid electrolyte tube 5 moves downward in the gap between the partition tube 11 and the solid electrolyte tube 5, and further passes through the solid electrolyte tube 5 as sodium ions, thereby passing through the sulfur S in the anode container 1 and the external circuit. Reacts with passing electrons to produce sodium polysulfide. At the time of charging, a reaction of forming sodium and sulfur occurs in reverse to discharging.

FIG. 3 shows such a conventional sodium-
It is principal part sectional drawing which shows the joining structure of the insulating ring and anode cylindrical fitting in a sulfur battery. The anode tubular metal fitting 3 has a cylindrical portion 3a and a flange portion 3b projecting from the lower end of the cylindrical portion 3a toward the inside of the cylindrical portion 3a. The insulating ring 4 is inserted into the cylindrical portion 3a of the anode tubular metal fitting 3, and the upper surface of the flange portion 3b and the lower end surface of the insulating ring 4 are heat-pressure bonded via a bonding material 12 such as a metal brazing material. ing.

Here, regarding the insertion of the insulating ring 4 into the cylindrical portion 3 a of the anode cylindrical fitting 3, the value C of the clearance 13 between the inner peripheral surface of the cylindrical portion 3 a and the outer peripheral surface of the insulating ring 4 is set.
The larger the value is, the easier the work is, and it is particularly preferable in consideration of mass production, automation of assembly work, and the like. However, if the value C of the clearance 13 is too large, a problem such as misalignment occurs.
Was set to be about 1 mm.

Meanwhile, in the sodium-sulfur battery, there is a temperature difference between when the battery is operating and when the battery is stopped. In a low temperature state when the battery is stopped, sodium polysulfide or sulfur solidifies, and the solid electrolyte tube 5 and the anode container 1 Will be mutually bound. When the temperature of the battery is lowered, both the solid electrolyte tube 5 and the anode container 1 undergo thermal contraction, but the thermal contraction of the metal anode container 1 is large, and the contraction of the anode container 1 is suppressed by the solid electrolyte tube 5 having small thermal contraction. Therefore, a downward load is applied to the joint between the insulating ring 4 connecting the solid electrolyte tube 5 and the anode container 1 to the anode cylindrical fitting 3 (in the direction of the arrow in FIG. 3).

Therefore, conventionally, in order to prevent the joint between the insulating ring 4 and the anode tubular metal fitting 3 from being damaged due to this load, an inner circumferential portion shrinking in the axial direction is formed on a part of the peripheral surface of the anode container 1. Measures such as forming a constriction in the plane direction to give a spring effect and reduce the load have been taken.

[0010]

However, even when the above measures are taken, cracks may occur if the strength of the connection end of the insulating ring 4 with the anode tubular fitting 3 is weak. In addition, this problem has become more prominent as the size of sodium-sulfur batteries has increased.

The present invention has been made in view of such a situation, and an object of the present invention is to provide an insulating ring and an insulating ring for a load caused by a difference in thermal contraction between a solid electrolyte tube and an anode container when a battery temperature is lowered. It is an object of the present invention to provide a joint structure capable of improving the strength reliability of a joint portion with an anode cylindrical fitting and preventing damage to the joint portion.

[0012]

According to the present invention, an insulating ring is joined to an open end of a solid electrolyte tube, and the insulating ring projects from a cylindrical portion and a lower end of the cylindrical portion toward the inside of the cylindrical portion. An anode cylindrical fitting having a flange portion,
In the joining structure of the insulating ring of the sodium-sulfur battery and the anode tubular metal fitting which are hot-pressed so that the upper surface of the flange part is joined to the lower end face of the insulating ring, the inner cylindrical part of the anode tubular metal fitting is A joint structure of an insulating ring and an anode cylindrical metal fitting in a sodium-sulfur battery, wherein a clearance value between a peripheral surface and an outer peripheral surface of the insulating ring is 0.15 mm or less.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In a joint structure between an insulating ring and an anode cylindrical metal fitting in a sodium-sulfur battery of the present invention, as shown in a sectional view of a main part of FIG.
The value C of the clearance 13 between the inner peripheral surface of the cylindrical portion 3a and the outer peripheral surface of the insulating ring 4 is set to 0.15 mm or less, preferably 0.025 to 0.15 mm.

By setting the value C of the clearance 13 in this manner, the bonding structure of the present invention has a higher bonding strength than the conventional bonding structure in which the value of the clearance is set to about 1 mm. Is shown. Although the reason for this is not clear, if the value C of the clearance 13 is set to be narrow so as to be 0.15 mm or less, as shown in FIG. 1, at the time of hot-press bonding between the anode cylindrical fitting 3 and the insulating ring 4, The joining material 12 such as a metal brazing material interposed between the upper surface of the flange portion 3b of the anode cylindrical fitting 3 and the lower end surface of the insulating ring 4 soaks up to a high position of the clearance 13 extending in the vertical direction. It is considered that the inner peripheral surface of the portion 3a and the outer peripheral surface of the insulating ring 4 are joined to increase the joint area between the anode cylindrical fitting 3 and the insulating ring 4.

As described above, except that the value C of the clearance 13 between the inner peripheral surface of the cylindrical portion 3 a of the anode tubular metal fitting 3 and the outer peripheral surface of the insulating ring 4 is set to be 0.15 mm or less. The joining structure of the present invention is not different from the above-mentioned conventional joining structure. That is, as in the prior art, the insulating ring 4 is inserted into the cylindrical portion 3a of the anode tubular metal fitting 3, and the upper surface of the flange portion 13b of the anode tubular metal fitting 3 and the lower end surface of the insulating ring 4 are made of metal brazing material. And the like.

[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.

(Embodiment) The value C of the clearance 13 between the inner peripheral surface of the cylindrical portion 3a and the outer peripheral surface of the insulating ring 4 shown in FIG.
However, as shown in Table 1, the anode cylindrical metal fitting 3 and the insulating ring 4 were produced in various dimensions so as to be 0.025 to 0.3 mm, and they were joined by heat and pressure to produce test specimens. As shown in FIG. 4, a load is applied to each of the test pieces manufactured in this manner from above the anode tubular metal fitting 3 via the pressing jig 20, and the load is received by the receiving jig 21 below the insulating ring 4. Then, the breaking strength of the joint between the anode cylindrical fitting 3 and the insulating ring 4 was measured. The results are shown in Table 1 and FIG.

[0018]

[Table 1]

As shown in Table 1 and FIG. 5, the breaking strength decreases as the value C of the clearance increases. By setting the value C of the clearance to 0.15 mm or less, a high bonding strength can be obtained. found.

[0020]

As described above, according to the present invention, it is possible to improve the strength reliability of the joint between the insulating ring and the anode tubular metal fitting. The reliability of the sulfur battery can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a principal part showing one embodiment of a joint structure of the present invention.

FIG. 2 is a cross-sectional view illustrating a general structure of a sodium-sulfur battery.

FIG. 3 is a sectional view of a main part showing a conventional joining structure.

FIG. 4 is an explanatory diagram showing a method for measuring the breaking strength of a joint in an example.

FIG. 5 is a graph showing the results of Examples.

[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 lid, 10 ... Cathode side terminal, 11 ... Partition tube, 12 ... Bonding material, 13 ... Clearance.

Claims (1)

[Claims] 1. An anode cylindrical metal fitting having an insulating ring joined to an open end of a solid electrolyte tube, and having a cylindrical portion and a flange projecting from a lower end of the cylindrical portion toward an inside of the cylindrical portion. In a joint structure of an insulating ring of a sodium-sulfur battery and an anode cylindrical fitting which are hot-pressed and joined such that an upper surface of the flange portion is joined to a lower end surface of the insulating ring, A joint structure between an insulating ring and an anode cylindrical fitting in a sodium-sulfur battery, wherein a value of a clearance between an inner peripheral surface and an outer peripheral surface of the insulating ring is 0.15 mm or less.