JPH09190837A - Sodium-sulfur battery - Google Patents

Abstract

(57) [Abstract] [Problem] To increase the strength reliability of a sodium-sulfur battery, it is effective to improve the strength of the interface of the hot-pressing portion. In particular, in order to improve the strength of the negative electrode active material against interfacial corrosion due to sodium, the synergistic effect of increasing the distance between the interface between the insulating material and the metal in the negative electrode hot press contact portion and changing the action direction of stress to reduce Improves corrosion life. A sodium-sulfur battery having a structure in which a solid electrolyte and an insulating material are interposed between a negative electrode made of sodium and a positive electrode made of sulfur, and a metal negative electrode container flange and an insulating material are heat-pressed via an intermediate material, A sodium-sulfur battery, characterized in that one or more concave surfaces and / or convex surfaces are provided at a joint interface between the insulating material of the heat press contact portion and the intermediate material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure at a joint between an insulating ring and a metal of a sodium-sulfur battery, and more particularly to a sodium-sulfur battery having a structure suitable for improving the life of the joint against corrosion of a negative electrode active material. Regarding

[0002]

2. Description of the Related Art The structure of a conventional sodium-sulfur battery is as follows.
For example, it is disclosed in JP-A-63-26947, JP-A-2-121272, and JP-A2-126572. The structure uses α-alumina as an insulating ring, and when the insulating ring and the steel positive electrode and negative electrode container flanges are hot pressed, an oxygen-free copper layer is provided on the α-alumina surface, and a nickel braze is applied thereon. After the coating process, heat pressure welding is performed,
The use of a corrosion-resistant nickel material improves the corrosion resistance of the hot press contact part, and when combining the insulating material and the solid electrolyte tube and the positive electrode and negative electrode, the thermal expansion coefficient is taken into consideration in consideration of thermal expansion coefficient. To improve cycle and corrosion resistance,
The positive electrode container is curved inward at the lower part of the hot press contact portion to form a concave groove to prevent movement of the positive electrode active material and to improve corrosion resistance.

Conventionally, as described above, the device for improving the corrosion resistance of the bonding interface material itself, the device for the generated stress, and the device for moving the liquid surface have been devised. However, no consideration has been given to increase the bonding length by changing the bonding path of the bonding portion and to improve the corrosion life of the negative electrode active material by changing the stress direction.

[0004]

In order to increase the strength reliability of the sodium-sulfur battery, it is effective to improve the strength of the interface of the hot press contact portion. In particular, in order to improve the strength of the negative electrode active material against interfacial corrosion due to sodium, the synergistic effect of increasing the distance between the interface between the insulating material and the metal in the negative electrode hot press contact portion and changing the action direction of stress to reduce Improves corrosion life.

[0005]

A first aspect of the invention for achieving the above object is a thermocompression-bonding portion between a negative electrode container flange and an insulating material, in which one or more concave surfaces or convex surfaces are provided on the insulating material side and the interface length of a corrosion target is increased. It is characterized by increasing the height, changing the action direction of stress and reducing it.

The second invention is characterized in that the insulating ring of the first invention is made of α-alumina and the intermediate material is made of an aluminum alloy.

A third invention is characterized in that, in the first invention, the negative electrode container flange is made of aluminum or an aluminum alloy.

FIG. 2 shows a structure in which the negative electrode container flange 2 and the insulating material 1 are joined by thermocompression bonding through the intermediate material 3, and a recess 12 is provided on the insulating material 1 side. Intermediate material 3 and insulation material 1
Is the target interface where corrosion of the negative electrode active material 11 is caused by sodium. The distance of the interface to be corroded becomes longer, and the corrosion life can be improved accordingly. Further, the corrosion crack generated from the inner end portion of the interface changes its path to the inside of the insulating material 1 when it progresses to the recess, so that the crack opening is suppressed, the direction of stress is changed, and the size becomes smaller. , Reduce the corrosion rate and improve the corrosion life. Further, FIG. 6 shows a case where the convex portion 13 is installed on the insulating material 1 side. The function and effect are exactly the same as the case where the recess 12 of FIG. 2 is provided, and the sodium corrosion life is improved.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the sodium-sulfur battery of the present invention is shown in FIGS. An insulating ring 1 made of α-alumina, whose linear expansion coefficient is not so different from that of the solid electrolyte tube, is glass-soldered onto the solid electrolyte tube 7 made of β ″ -alumina having sodium conductivity.
The negative electrode container flange 2 and the positive electrode container flange 5 made of steel are heat-pressure welded to each other at a high temperature via the ring-shaped intermediate member 3 made of aluminum. A sodium negative electrode active material 11 is stored inside the solid electrolyte tube 7 made of β ″ -alumina, and sulfur of the positive electrode active material 9 impregnated in the mold is stored outside.
In this embodiment, as shown in FIG. 2, a concave portion is provided in the insulating ring 1 of the negative pressure side hot press contact portion to increase the distance of the sodium corrosion target interface, change the direction of stress, and reduce the generated stress. The effect of improving the corrosion life can be realized.

FIG. 3 is a modification of FIG. 2, and shows a case where the intermediate member is divided into two ring members 3 and a small ring member 14 and subjected to thermal pressure welding. The function and effect are the same as in the case of FIG.

FIG. 4 is a modified example of FIG.
When the protrusion 16 corresponding to the recess of alumina is provided, the function and effect are the same as in the case of FIG.

FIG. 5 shows a modified example of FIG. 2 and shows a case where the negative electrode container flange 2 is integrally molded with the same aluminum or aluminum alloy as the intermediate material 3. The obtained action and effect are similar to those of FIG.

FIG. 6 shows a case in which the convex portion 13 is provided on the α-alumina insulating ring 1 at the negative electrode hot press contact portion. While increasing the distance of the sodium corrosion target interface, change the direction of stress,
Moreover, the effect of reducing the generated stress and improving the sodium corrosion life can be realized.

FIG. 7 shows a modification of FIG. 6 and shows a case where the intermediate member is divided into three ring members 3, 14 and 15 and subjected to thermal pressure welding.

FIG. 8 is a modified example of FIG. 6, in which the intermediate member 3 has α
When the concave surface corresponding to the convex portion of alumina is provided, the function and effect are the same as in the case of FIG.

FIG. 9 is a modified example of FIG. 6, and shows a case where the negative electrode container flange 2 is integrally molded with the same aluminum or aluminum alloy as the intermediate material 3. The obtained action and effect are similar to those in the case of FIG.

[0017]

According to the present invention, the distance between the interface between the insulating material and the metal at the negative electrode hot press contact portion can be increased, the direction of stress can be changed, and the stress can be reduced. Sodium Corrosion life is improved and sodium
The strength reliability of the sulfur battery can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a sodium-sulfur battery of the present invention.

FIG. 2 is an explanatory diagram of a case where a recess is provided in an insulating material according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of an application modification example of FIG. 2.

FIG. 4 is an explanatory diagram of an application modification example of FIG.

FIG. 5 is an explanatory diagram of an application modification example of FIG. 2.

FIG. 6 is an explanatory view when a convex portion is provided on an insulating material according to an embodiment of the present invention.

7 is an explanatory diagram of an application / modification example of FIG.

8 is an explanatory diagram of an application / variation example of FIG.

9 is an explanatory diagram of an application / variation example of FIG.

[Explanation of symbols]

1 ... Insulating material, 2 ... Negative electrode container flange, 3 ... Intermediate material, 4 ...
Negative electrode container, 5 ... Positive electrode container flange, 6 ... Positive electrode container, 7 ...
Solid electrolyte tube, 8 ... Safety tube, 9 ... Positive electrode active material, 10 ... Negative electrode terminal, 11 ... Negative electrode active material, 12 ... Insulator recess, 13 ...
Insulating material convex portion, 14, 15 ... Small intermediate material ring, 16 ... Intermediate material protruding portion.

Claims (3)

[Claims] 1. A sodium-sulfur battery having a structure in which a solid electrolyte and an insulating material are interposed between a negative electrode made of sodium and a positive electrode made of sulfur, and a metal negative electrode container flange and an insulating material are thermocompression-bonded via an intermediate material. A sodium-sulfur battery, characterized in that one or more concave surfaces and / or convex surfaces are provided at a joint interface between the insulating material of the hot press contact portion and the intermediate material. 2. The sodium-sulfur battery according to claim 1, wherein the insulating material is α-alumina and the intermediate material is aluminum or an aluminum alloy. 3. The sodium-sulfur battery according to claim 1, wherein the negative electrode container flange is made of aluminum or an aluminum alloy.