JP4574196B2 - Joining structure of insulating ring and anode cylindrical fitting in sodium-sulfur battery - Google Patents

Description

  The present invention relates to a joining structure of an insulating ring and an anode cylindrical metal fitting in a sodium-sulfur battery, and more particularly to an insulating ring and an anode against a load caused by a difference in thermal contraction and expansion between a solid electrolyte tube and an anode container when the battery is heated and lowered. The present invention relates to a joint structure that can improve the strength reliability of a joint portion with a cylindrical metal fitting.

  A sodium-sulfur battery is a β-alumina solid electrolyte that has molten metal sodium as a cathode active material on one side and molten sulfur as an anodic active material on the other side, and both have selective permeability to sodium ions. It is a high-temperature secondary battery that is isolated at a temperature of 300 to 350 ° C.

For example, as shown in FIG. 2, the structure of such a sodium-sulfur battery includes a cylindrical anode container 1 that contains molten sulfur S impregnated with carbon felt or the like, and a cartridge (sodium that contains molten metal sodium Na). Protective tube) 6, this cartridge 6 is housed inside, and a bottomed cylindrical solid electrolyte tube 5 having a function of selectively transmitting sodium ions Na ^+, and a gap between the cartridge 6 and the solid electrolyte tube 5 And a bottomed cylindrical partition tube 11 disposed at a predetermined interval from the cartridge 6 and the solid electrolyte tube 5.

  The solid electrolyte tube 5 is coupled to the anode container 1 via an α-alumina insulating ring 4 and an anode cylindrical fitting 3 which are glass-bonded to the open end thereof. A cathode fitting 8 is hot-pressure bonded to the upper end surface of the insulating ring 4, and a cathode lid 9 is welded and fixed to the cathode fitting 8. An anode-side terminal 2 and a cathode-side terminal 10 are provided on the outer periphery 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 sodium Na in the cartridge 6 is passed through the small hole 7 provided at the bottom of the cartridge by the inert gas G. Pressurized in the outflow direction.

  In the sodium-sulfur battery having such a structure, 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 and then climbs over the upper end of the partition tube 11. Then, it moved downward in the gap between the partition wall tube 11 and the solid electrolyte tube 5, further passed through the solid electrolyte tube 5 as sodium ions, and passed through the sulfur S in the anode container 1 and the external circuit. Reacts with electrons to produce sodium polysulfide. When charging, contrary to discharging, sodium and sulfur are formed.

  FIG. 3 is a cross-sectional view of an essential part showing a joint structure between an insulating ring and an anode cylindrical fitting in such a conventional sodium-sulfur battery. The anode cylindrical 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 cylindrical metal fitting 3, and the upper surface of the flange 3b and the lower end surface of the insulating ring 4 are hot-pressure bonded through a bonding material 12 such as a metal brazing material. Yes.

  Here, the insertion of the insulating ring 4 into the cylindrical portion 3a of the anode cylindrical metal fitting 3 is performed with a larger 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. It is easy, and is particularly preferable when considering mass production and automation of assembly work. On the other hand, when the value C of the clearance 13 is too large, problems such as misalignment occur. Therefore, conventionally, the value C of the clearance 13 is set to be about 1 mm.

Further, the sodium-sulfur battery has a temperature difference between when the battery is operated and when it is stopped. In a low temperature state when the battery is stopped, sodium polysulfide or sulfur is solidified, and the solid electrolyte tube 5 and the anode container 1 are bound to each other. It will be. Therefore, when the temperature of the battery is lowered, a downward load is applied to the joint between the insulating ring 4 and the anode cylindrical fitting 3 that join the solid electrolyte tube 5 and the anode container 1 (in the direction of the arrow in FIG. 3). For this reason, conventionally, in order to prevent damage to the joint between the insulating ring 4 and the anode cylindrical fitting 3 due to this load, a part of the peripheral surface of the anode container 1 is axially contracted in the inner peripheral surface direction. Measures have been taken to reduce the load by forming a constriction to provide a spring effect.

However, even when the above measures are taken, a crack or the like may occur at the joint between the insulating ring 4 and the anode cylindrical fitting 3. It has been proposed that a high bonding strength can be achieved by setting the clearance between the inner circumferential surface of the insulating ring and the outer circumferential surface of the insulating ring as narrow as 0.15 mm or less (see Patent Document 1).
Although this proposal can solve the above-mentioned conventional problems, it is a preferable solution. However, the clearance is as narrow as 0.15 mm or less, and both the insulating ring 4 and the anode cylindrical metal fitting 3 require extremely high dimensional accuracy. There is a request for further improvement.
JP 2000-90967 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is not to increase the dimensional accuracy of an insulating ring made of ceramics to a predetermined level or more, and to provide an insulating ring and an anode cylindrical metal fitting. It is an object of the present invention to provide a joint structure capable of improving strength reliability by increasing the joint strength of the joint part to a predetermined value or more and preventing damage to the joint part.

According to the present invention, an insulating ring made of ceramic is joined to the open end of a solid electrolyte tube, and a cylindrical portion and a flange portion projecting from the lower end of the cylindrical portion toward the inside of the cylindrical portion are attached to the insulating ring. In the joining structure of the insulating ring of the sodium-sulfur battery and the anode cylindrical fitting, the anode cylindrical fitting having the anode cylindrical fitting having a hot-pressure bonding so that the upper surface of the flange portion is joined to the lower end surface of the insulating ring, The clearance between the inner peripheral surface of the cylindrical portion of the metal fitting and the outer peripheral surface of the insulating ring is more than 0.15 mm and not more than 0.6 mm, and the insulating ring is a fired product that is unpolished. A joining structure of an insulating ring and an anode cylindrical fitting in a sodium-sulfur battery is provided.

  In the joining structure of the present invention, it is preferable that the clearance between the inner peripheral surface of the cylindrical portion of the anode cylindrical metal fitting and the outer peripheral surface of the insulating ring be greater than 0.15 mm and not greater than 0.45 mm.

According to the joining structure of the present invention, the clearance between the inner peripheral surface of the cylindrical portion of the anode cylindrical metal fitting and the outer peripheral surface of the insulating ring is more than 0.15 mm, 0.6 mm or less, preferably more than 0.15 mm, 0.45 mm. Since the dimensional accuracy of an insulating ring generally made of ceramic such as α-alumina is not increased beyond a predetermined level, a non-polished sintered product can be used as the insulating ring. Even if it is larger than 15 mm, the joint strength of the joint portion between the insulating ring and the anode cylindrical metal fitting can be increased more than a predetermined value, and a remarkable effect can be achieved that higher strength reliability can be achieved. It is.

Hereinafter, although embodiment of this invention is described, it cannot be overemphasized that this invention is not limited to the following embodiment.
In the joining structure of the insulating ring and the anode cylindrical metal fitting in the sodium-sulfur battery of the present invention, as shown in the cross-sectional view of the main part of FIG. 1, the inner peripheral surface of the cylindrical portion 3a of the anode cylindrical metal fitting 3 is insulated. The value C of the clearance 13 with the outer peripheral surface of the ring 4 is more than 0.15 mm and less than 0.6 mm, preferably more than 0.15 mm and less than 0.45 mm. It is what is used.

  In the technique of Japanese Patent Application Laid-Open No. 2000-90967 previously proposed by the present applicant, the clearance between the inner peripheral surface of the cylindrical portion 3a of the anode cylindrical metal fitting 3 and the outer peripheral surface of the insulating ring 4 is 0.15 mm or less. Since it is extremely narrow, both the insulating ring 4 and the anode cylindrical metal fitting 3 are required to have extremely high dimensional accuracy. In particular, since the insulating ring 4 is usually made of ceramics such as α-alumina, it is high in consideration of firing shrinkage and the like. In order to obtain dimensional accuracy, it is almost essential to perform peripheral processing after firing. Then, it is presumed that performing the outer periphery processing causes fine processing flaws on the outer peripheral surface of the insulating ring 4.

  The present inventor has the idea opposite to the above, relaxes the clearance a little and makes it 0.6 mm or less, so that the outer peripheral processing after firing is not required for the insulating ring, and it is unpolished with the fired product as the insulating ring. By using this, the joint strength of the joint portion between the insulating ring and the anode cylindrical metal fitting can be made equal to or greater than that of JP 2000-90967 A.

  As described above, the value C of the clearance 13 between the inner peripheral surface of the cylindrical portion 3a of the anode cylindrical metal fitting 3 and the outer peripheral surface of the insulating ring 4 is 0.6 mm or less, and the fired product is used as the insulating ring. However, except that an unpolished one is used, the joining structure of the present invention is not different from the conventional joining structure described above. That is, as in the prior art, the insulating ring 4 is inserted into the cylindrical portion 3a of the anode cylindrical fitting 3, and the upper surface of the flange portion 13b of the anode cylindrical fitting 3 and the lower end surface of the insulating ring 4 are made of metal brazing material. Hot-pressure bonding is performed through a bonding material 12 such as the above.

Hereinafter, the present invention will be described in more detail based on examples.
Example 1
The anode tubular fitting 3 made of an aluminum alloy so that the value C of the clearance 13 between the inner circumferential surface of the cylindrical portion 3a of the anode tubular fitting 3 and the outer circumferential surface of the insulating ring 4 is 0.1 to 0.6 mm. And, the non-polished insulating ring 4 made of a fired product made of α-alumina, and the insulating ring 4 made of α-alumina and subjected to outer peripheral processing after firing were produced, and these were subjected to hot-pressure bonding to produce a test piece. As shown in FIG. 4, a load is applied from the upper part of the anode cylindrical fitting 3 to the test piece thus produced through the pushing jig 20, and the load is received by the receiving jig 21 at the lower part of the insulating ring 4. The fracture strength of the joint between the anode cylindrical fitting 3 and the insulating ring 4 was measured. The result is shown in FIG. In FIG. 5, line A shows the result of the fired / unpolished insulating ring, and line B shows the result of the insulating ring subjected to the outer peripheral processing after firing.

(Example 2)
Next, with respect to the insulating ring 4, the bending strength was measured for the non-polished baked product made of α-alumina and the baked product made of α-alumina and subjected to outer peripheral processing after firing. The result is shown in FIG.

As shown in FIG. 5, in the case of a fired / unpolished insulating ring, the breaking strength is 0.1 mm to 0.6 mm even if the clearance is increased from 0.1 mm to 0.6 mm. It can be seen that even when the clearance is slightly increased, the fracture strength is equal to or greater than that of the insulating ring that has undergone outer periphery processing after firing.
Further, as shown in FIG. 6, it can be seen that the bending strength of the insulating ring is about 100 MPa higher in the unpolished product than in the polished product.

  The present invention can be preferably applied as a joint structure between an insulating ring and an anode cylindrical fitting in a sodium-sulfur battery.

It is principal part sectional drawing which shows one Embodiment of the junction structure of this invention. It is sectional drawing which shows the general structure of a sodium-sulfur battery. It is principal part sectional drawing which shows the joining structure of the insulating ring and anode cylindrical metal fitting in the conventional sodium-sulfur battery. It is explanatory drawing which shows the measuring method of the fracture strength of the junction part in an Example. 3 is a graph showing the results of Example 1. 10 is a graph showing the results of Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Anode container, 2 ... Anode side terminal, 3 ... Anode cylindrical metal fitting, 4 ... Insulation ring, 5 ... Solid electrolyte pipe, 6 ... Cartridge, 7 ... Small hole, 8 ... Cathode metal fitting, 9 ... Cathode lid, 10 ... Cathode side terminal, 11 ... partition wall tube, 12 ... bonding material, 13 ... clearance.

Claims (2)

An insulating ring made of ceramic is joined to the open end of the solid electrolyte tube, and an anode cylindrical fitting having a cylindrical portion and a flange portion projecting from the lower end of the cylindrical portion toward the inside of the cylindrical portion is attached to the insulating ring. In the joining structure of the insulating ring of the sodium-sulfur battery and the anode cylindrical metal fitting which are hot-pressure joined so that the upper surface of the flange portion is joined to the lower end surface of the insulating ring,
The clearance between the inner peripheral surface of the cylindrical portion of the anode cylindrical metal fitting and the outer peripheral surface of the insulating ring should be more than 0.15 mm and not more than 0.6 mm, and the insulating ring should be an unpolished fired product. The junction structure of the insulating ring and anode cylindrical metal fitting in a sodium-sulfur battery characterized by these.   The insulation ring and anode cylinder shape in a sodium-sulfur battery according to claim 1, wherein the clearance between the inner peripheral surface of the cylindrical portion of the anode cylindrical metal fitting and the outer peripheral surface of the insulation ring is more than 0.15 mm and 0.45 mm or less. Bonding structure with metal fittings.

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