JPH053049A - Manufacture of sodium sulfur battery - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing soclium-sulfur batteries wherein stress concentration is minimized and residual heat stress is levelled by allowing a insert layer to continuously change in thickness of an Al corresponding to the location of a recess. CONSTITUTION:A negative slsctrode tube 4 and a positive electrode tube 5 are joined with alumina ring 3 installed in between. The joining of the alumina ring 3 and each of the negative electrode tube 4 and the positive electrode tube 5 is carried out by using an Al insert having a brazing material 2 as a skin layer on both sides of a core. A recess 9 is formed in a semicircle or a half sllipse on the inner and outer peripheries (at least the outer periphery) of the Al insert joining portion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a sodium-sulfur battery, and more particularly to a method for manufacturing a sodium-sulfur battery suitable for reducing residual thermal stress generated at the time of joining to obtain high strength and high reliability. ..

[0002]

2. Description of the Related Art A conventional method for manufacturing a sodium-sulfur battery is disclosed in Japanese Patent Application Laid-Open No. 62-72577. From the surface, the thickness of the Al insert material was 2 mm or more.

[0003]

The above-mentioned prior art does not consider the concentration of residual stress generated at the end faces of the joint portion which acts on a member such as alumina, which is brittle and has a large variation in strength. There was a problem in terms.

An object of the present invention is to provide a sodium-sulfur battery which reduces stress concentration generated at the interface between the Al insert material and the ceramic material, has high strength against internal pressure or tensile load, and is excellent in reliability. Especially.

[0005]

In order to achieve the above object, the inner and outer peripheral surfaces of the Al insert in the joined body are recessed to reduce the stress concentration generated at the joined end portion.

[0006]

[Function] By forming a semi-circular or semi-elliptical recess in the Al insert inside and outside the joint, A near the joint end can be obtained.
l The insert thickness varies continuously. As a result, residual thermal stress generated at the joint ends is not concentrated and smoothed, so that a sodium-sulfur battery with high strength and high reliability can be obtained.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

Example (1) FIG. 4 is a sectional view of a sodium-sulfur battery. The solid electrolyte bag tube 6 is surrounded by the anode tube 5, and the cathode tube 4 is arranged above. The open end of the solid electrolyte tube 6 is joined to the inner peripheral surface of the electrically insulating alumina ring 3 by glass solder. Cathode tube 4 and cathode tube 5 are bonded to the upper and lower surfaces of the alumina ring 3 different from the above bonding surface so that the alumina ring 3 is sandwiched therebetween.

The joining of the cathode tube 4 and the cathode tube 5 will be described with reference to a simulated short test piece shown in FIG.

As the cathode tube 4 and the anode tube 5, mild steel tubes are used, and a Cr layer is formed on the surface by a chromizing treatment from the viewpoint of corrosion resistance, and an alumina ring 3 is sandwiched between both tubes.

Between the alumina ring 3 and the cathode tube 4 and the anode tube 5, an Al alloy is used as a core material and Al-10%.
Insert a 0.16 mm thick clad brazing material 2 using Si-2% Mg alloy as both skin materials, and insert a pure Al material 1 with a thickness of ± 3 mm between the brazing materials to form Al.
Forming insert material.

The pure Al material 1 inserted into the anode tube 5 in FIG. 1 has a simple ring shape, which is a conventional joining method, and has a cathode side 4
The pure Al material 1 inserted in was inserted into the pure Al 1 having an inner diameter and an outer diameter in advance so that a semicircular depression having a diameter of the Al insert thickness after joining was obtained.

This test piece was placed in a vacuum atmosphere of 10 to ³ Pa,
Bonding was performed by heating at a bonding temperature of 873 K and a bonding pressure of 5 MPa and maintaining the pressure.

A strain gauge was attached to the outer circumference of the alumina ring 3 of the obtained test piece, the Al insert was completely cut and removed, and the axial residual thermal stress at the time of bonding acting on the alumina ring 2 was measured. Is shown in FIG.

When the conventional Al insert is not provided with a depression, a high residual stress of 100 MPa is generated near the joint interface, and the stress is concentrated on this portion.

On the other hand, in the Al insert material of the present invention provided with a semicircular recess, the residual stress in the vicinity of the bonding interface is about 30 MPa, which is one-third that of the conventional method.

Further, a mild steel lid was welded to the anti-joining surface of the cathode tube 4 and the anode tube 5 of the test piece shown in FIG. 1 to perform an internal pressure fracture test. As a result, the cathode side anode side was made of a conventional Al insert material. The joined ones broke when the internal pressure was 2.4 MPa,
The fracture position was the bonded interface alumina ring portion.

On the other hand, the Al insert material provided with a semi-circular recess has a fracture internal pressure of 5.3 MPa, which is about twice that of the conventional method, and the fracture position is at the interface between the cathode and the anode tube and the Al insert material. there were.

Embodiment (2) FIG. 3 shows another embodiment in which the joining portion is enlarged in the joining configuration diagram shown in FIG.

A chamfered portion is provided on the outer peripheral joint surface side of the cathode tube 4 and the alumina ring 3, and the structure of the Al insert material is the same as that of the embodiment (1), but pure Al1 has a small outer diameter. Not provided.

Instead of this, a semi-elliptical splitting jig 7 having a convex shape on the inner diameter side of the joined body having the apex of the ellipse as the chamfering position of the joining surface is inserted, and the splitting jig pressing ring 8 is placed on the outside thereof. They were arranged and joined under the same conditions as in Example (1) with the applied pressure increased to 10 MPa. At this time, the pure Al1 is plastically deformed and deformed following the outer periphery of the semi-elliptical splitting jig, and a semi-elliptical recess is formed on the outer periphery of the Al insert after joining.

The residual stress of the chamfered portion of the alumina ring of this joined body was measured by the same method as in Example (1). For comparison, the semi-elliptical jig 7 was not installed, the outer diameter of pure Al1 was joined to the outer diameter of the cathode tube 4 and the alumina ring 3, and the Al insert material that had plastically flowed into the chamfered portion of the alumina ring was locally applied. The residual stress of this chamfered portion was also measured.

As a result, in the conventional method, the residual stress in the chamfered portion was 150 MPa because it was closer to the joint interface, and extremely large stress concentration occurred. On the other hand, Example (2)
The residual stress of the joined product of No. 30 MPa is the same as in Example (1).
Then, it was reduced to 1/5 of that of the conventional joining method, and stress concentration was hardly recognized.

[0024]

As described above, in joining the cathode and anode tubes of the sodium-sulfur battery and the alumina ring with the Al insert material, the inner and outer peripheral surfaces of the Al insert material are larger than the semi-circular shape. A dimple with an elliptical shape is provided A
By continuously changing the thickness of the insert, the concentration of residual stress generated at the joint end can be reduced, so that a high strength and highly reliable sodium-sulfur battery can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a joined product according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a residual stress distribution in an outer peripheral portion of an alumina ring of the joined product of FIG.

FIG. 3 is an enlarged vertical sectional view of a joined product of another embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view of the entire sodium-sulfur battery.

[Explanation of symbols]

1 ... Pure Al, 2 ... Brazing material, 3 ... Alumina ring, 4 ... Cathode tube, 5 ... Anode tube.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Sugawara 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi Works

Claims (1)

Claim: What is claimed is: 1. A metallic cathode and anode tube is arranged on the other surface of an electrically insulating ceramics ring soldered to the open end of a sodium ion conductive solid electrolyte tube, An Al-Si alloy on both joint surfaces between the cathode and cathode tubes, and Al or an Al alloy consisting of three layers between them.
In a method for manufacturing a sodium-sulfur battery in which heating and pressurization are performed via an insert material, the outer circumference of the joint Al insert or both the inner circumference and the outer circumference is larger than a semicircular shape having a diameter of the Al insert, and a diameter The method for producing a sodium-sulfur battery is characterized in that it is recessed into a range smaller than a semi-elliptical shape whose major axis is 1.5 times as long as the above.