JPH08236148A - Sodium-sulfur battery - Google Patents

Abstract

PURPOSE: To provide a sodium-sulphur battery in which sodium corrosion strength is improved and reliability of strength is improved. CONSTITUTION: A sodium conductive solid electrolyte tube is provided between a negative electrode vessel containing sodium as negative electrode active material and a positive electrode vessel containing sulphur as positive active material, a negative electrode vessel flange 2 and a positive electrode vessel flange are heat pressure welded to an insulation ring 1 joined to the solid electrolyte tube via intermediate material 3. In this sodium-sulphur battery, a protrusion 16 is provided at a sodium side end portion on a bottom face of the negative electrode vessel flange 2 touching the intermediate material 3, and the negative electrode vessel flange 2 having the protrusion 16 is heat pressure welded to the insulation ring 1 via the intermediate material 3. Heat pressure welding applied pressure at the sodium side end portion of a negative electrode heat pressure welded portion is locally increased, thereby.

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 an intermediate material of a sodium-sulfur battery,
In particular, the present invention relates to a sodium-sulfur battery which is favorable for improving the reliability of corrosion strength due to the negative electrode active material at the joint interface.

[0002]

2. Description of the Related Art The structure of a conventional sodium-sulfur battery is
For example, JP-A-63-26947 and JP-A-2-12
1272 and JP-A-2-126572. 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. We carry out thermal pressure welding after the coating process, and improve the corrosion resistance of the thermal pressure welding part by using a corrosion resistant nickel material, and at the time of joining combination of insulating material and solid electrolyte tube and positive electrode and negative electrode, the thermal expansion coefficient Considering the generation of thermal stress, improve the thermal cycle and corrosion resistance, and prevent the positive electrode active material from moving by curving the positive electrode container inward at the lower part of the heat press contact part and forming a concave groove. Then, a device for improving the corrosion resistance is made.

As a method for improving the corrosion resistance of the negative electrode and the positive electrode active material at the interface between the insulating ring and the negative electrode and the positive electrode container flange joint, a method of using the material itself as a corrosion resistant material, and structurally a liquid and a mist of the negative electrode and the positive electrode active material. A method of improving the corrosion resistance by preventing the dew condensation liquid from adhering to the joint can be considered.

[0004]

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, regarding the improvement of corrosion resistance to the negative electrode active material in consideration of the pressure distribution at the time of hot press contact of the flange joint part of the negative electrode container, particularly, the applied pressure at the sodium side end of the corrosion target part is applied with a relatively small heat press contact load. No consideration was given to increase the corrosion strength of the negative electrode active material by increasing the size.

In order to improve the strength reliability of the sodium-sulfur battery, it is effective to improve the strength of the interface of the hot press contact portion.

The present invention has been made in view of such circumstances, and in order to improve the strength of the negative electrode active material against interfacial corrosion due to sodium, the pressure applied to the sodium pressure end of the negative electrode heat pressure contact portion is locally applied. It is an object of the present invention to provide a sodium-sulfur battery that has improved sodium corrosion resistance and thus improved strength reliability.

[0008]

The sodium-sulfur battery of the present invention is a sodium-sulfur battery between a negative electrode container containing sodium as a negative electrode active material and a positive electrode container containing sulfur as a positive electrode active material. In a sodium-sulfur battery provided with a solid electrolyte tube and configured to heat-press the negative electrode container flange and the positive electrode container flange with an insulating ring joined to the solid electrolyte tube via an intermediate material, It is characterized in that a pressure increasing means for locally increasing the pressure applied by the thermal pressure welding at the sodium side end is provided.

In the sodium-sulfur battery of the present invention, as the pressure increasing means, a projection is provided on the sodium-side end of the lower surface of the negative electrode container flange which is in contact with the intermediate material, and the negative electrode container flange having the projection is used as the intermediate material. It is characterized in that it is heat-pressed to the insulating ring through.

In the sodium-sulfur battery of the present invention, as the pressure increasing means, the plate thickness of the negative electrode container flange in contact with the intermediate material is tapered so that the sodium side end of the negative electrode container flange is thickened, and the taper is provided. The negative electrode container flange having the above is heat-pressed to the insulating ring via an intermediate material.

In the sodium-sulfur battery of the present invention, as the pressure increasing means, a projection is provided so that the plate thickness of the intermediate material becomes thicker at the sodium side end portion, and the negative electrode is provided through the intermediate material having the projection. The container flange is heat-pressed to the insulating ring.

In the sodium-sulfur battery of the present invention, as the pressure increasing means, a taper is provided so that the plate thickness of the intermediate material becomes thicker at the sodium side end, and the negative electrode is provided through the intermediate material having the taper. The container flange is heat-pressed to the insulating ring.

In the sodium-sulfur battery of the present invention, as the pressure increasing means, a protrusion is provided so that the thickness of the insulating ring in contact with the intermediate material becomes thicker at the sodium side end.
The negative electrode container flange is heat-pressed to the insulating ring having the projection through the intermediate member.

In the sodium-sulfur battery of the present invention, as the pressure increasing means, a taper is provided so that the thickness of the insulating ring in contact with the intermediate material becomes thicker at the sodium side end, and the insulating ring having the taper is formed. It is characterized in that the negative electrode container flange is heat-pressed through the intermediate material.

The sodium-sulfur battery of the present invention is characterized in that the insulating ring is made of α-alumina and the intermediate material is made of aluminum.

The sodium-sulfur battery of the present invention is characterized in that the insulating ring is made of α-alumina and the intermediate material is made of an aluminum alloy.

The sodium-sulfur battery of the present invention is characterized in that the negative electrode container flange and the intermediate material are integrally molded of aluminum.

The sodium-sulfur battery of the present invention is characterized in that the negative electrode container flange and the intermediate material are integrally molded of an aluminum alloy.

[0019]

FIG. 4 shows the applied pressure P during the hot press welding of the negative electrode and the corrosion depth of the interface between the intermediate material and the α-alumina when the temperature rising / falling heat cycle was repeated 20 times between 330 ° C. and 30 ° C. in sodium. Data obtained by experimentally determining the relationship of a is shown.

The relationship between the applied pressure P and the corrosion depth a at the time of hot press contact is such that when the applied pressure P of hot press contact is large, the corrosion depth a is also a small value, and the applied pressure for improving the sodium corrosion resistance is It can be seen that increasing P is effective because of the effect of pushing out an oxide film, impurities, etc. from the interface at the time of bonding and the increase of adhesion.

In FIG. 4, as an application example of the present invention, a protrusion for increasing the heat pressure welding applied pressure P is provided at the sodium side end portion on the negative electrode side in contact with the intermediate material, and the heat pressure welding applied pressure P is 10 MPa on average. The result when the pressure was applied is indicated by a triangle. Corrosion depth is about 0.2 mm, and thermal pressure applied pressure P
It can be seen that the corrosion depth is about 0.2 mm, which is smaller than 1.8 mm in the case where no protrusion is provided, which is a means for increasing the pressure, and the corrosion strength is equivalent to that when the average applied pressure P is 30 MPa.

In the sodium-sulfur battery according to the invention,
As shown by the above results, even if the average load is small, the sodium corrosion strength can be improved by locally increasing the pressure applied to the sodium pressure side of the heat pressure contact portion.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. The construction of one embodiment of the sodium-sulfur battery according to the present invention is shown in FIGS. In these figures, on the upper part of the sodium-conducting β ″ -alumina solid electrolyte tube 7, there is not much difference in linear expansion coefficient from the solid electrolyte tube 7 α−.
An insulating ring 1 made of alumina is joined by glass soldering. A negative electrode container flange 2 and a positive electrode container flange 5 made of steel are heat-welded to the insulating ring 1 at a high temperature via a ring-shaped intermediate material 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, as means for increasing the applied pressure under the heat pressure welding at the sodium side end portion of the negative electrode side heat pressure contact portion, a projection is formed on the sodium side end portion of the negative electrode flange 2 in contact with the intermediate material 3. 16 is installed.

According to the present embodiment, the effect of increasing the sodium corrosion strength by increasing the pressure applied in the pressure contact at the sodium side can be realized. In the embodiment shown in FIG. 1, a stopper 14 for positioning the intermediate material is provided so that the pressure can be applied more reliably through the intermediate material.

FIG. 3 shows a modification of the embodiment shown in FIG. As shown in the figure, in this embodiment, a taper 17 is provided in place of the protrusion 16 as a means for increasing the pressure applied to the sodium-side end of the negative-side heat-pressure contact portion in the heat-pressure welding. The function and effect are basically the same as those of the embodiment shown in FIG.

Next, FIG. 5 shows the configuration of another embodiment of the present invention. In this embodiment, the intermediate member 3 is provided with a means for increasing the pressure applied to the sodium-side end portion of the negative-side heat-pressure welding portion. A protrusion 12 for increasing the applied pressure by thermal pressure welding is provided on the upper portion of the intermediate member 3, that is, on the negative electrode flange 2 side.
According to this embodiment, the protrusion can be easily processed, and the effect of improving the sodium corrosion strength can be realized.

FIG. 6 shows a modification of the embodiment shown in FIG. In the present embodiment, the protrusion 12 for increasing the pressure applied by the thermal pressure welding is provided on the lower portion of the intermediate material 3, that is, on the insulating ring 1 side. The effect of this embodiment is similar to that of the embodiment shown in FIG.

FIG. 7 shows a modification of the embodiment shown in FIG. In the present embodiment, the taper 18 is provided on the upper side of the intermediate material 3 instead of providing the projection 12 for increasing the pressure applied by the heat press contact on the intermediate material 3. The effect of this embodiment is similar to that of the embodiment shown in FIG.

Further, FIGS. 8 and 9 show modified examples of the embodiment shown in FIG. The embodiment shown in FIG. 8 is provided with a taper 18 for increasing the thermal pressure applied pressure on the lower side of the intermediate material 3, and the embodiment shown in FIG. 9 is provided on the upper side and the lower side of the intermediate material 3. The taper 18 is provided. Also in these two examples, the sodium corrosion strength can be improved by increasing the pressure applied to the sodium-side end of the negative electrode heat-pressure contact portion.

Next, FIG. 10 shows the configuration of another embodiment of the present invention. In this embodiment, the insulating ring 1 is provided with a means for increasing the pressure applied to the sodium-side end of the negative-side heat-pressure-welded portion. That is, the protrusion 13 for increasing the pressure applied by the heat press contact to the sodium side end of the insulating ring 1.
Is provided.

According to this embodiment, the sodium corrosion strength of the sodium-sulfur battery can be improved.

FIG. 11 shows a modification of the embodiment shown in FIG. In this embodiment, a taper 19 is provided on the insulating ring 1 instead of the protrusion 13 in the embodiment shown in FIG. The effects of this embodiment are similar to those of the embodiment shown in FIG.

Next, FIG. 12 shows the configuration of another embodiment of the present invention. In the present embodiment, the negative electrode container flange 2 and the intermediate material 3 are integrally formed of aluminum or an aluminum alloy, and a means for locally increasing the heat pressure welding applied pressure at the sodium side end of the negative electrode heat pressure welding portion is provided. is there.

According to this embodiment, a projection 16 is provided on the sodium side end of the negative electrode container flange 2 underneath to locally increase the pressure applied to the sodium side end of the negative electrode container flange 2 during hot press contact. This has the effect of improving sodium corrosion in a sodium-sulfur battery.

FIG. 13 shows a modification of the embodiment shown in FIG. In this embodiment, the protrusion 13 for increasing the pressure applied by the thermal press contact is provided on the insulating ring 1 side. The effect of this embodiment is similar to that of the embodiment shown in FIG.

In the embodiments shown in FIGS. 12 and 13, it is also effective to install a taper instead of the protrusion 16 and the protrusion 13, respectively.

When the means for increasing the pressure applied to the sodium-side end of the negative-side heat-pressure-welded portion of the present invention is installed, the applied-pressure distribution at the negative-side heat-pressure-welded portion is the average applied pressure as shown in FIG. About 3 times the applied pressure is generated at the sodium side end compared to Pm, and the average applied pressure P is on the outside.
The applied pressure is 40 to 50% of m.

The present invention has the advantage that the strength against sodium corrosion can be secured by increasing the applied pressure at the sodium-side end of the negative-side heat-pressure welded portion during heat-pressure welding with a relatively small load.

On the other hand, in the case where the present invention is not adopted and the applied pressure load is uniform over the entire surface as shown in FIG. 15, an extremely large load (about 3 times that of the present invention) is required.

Further, the same effect as that of the present invention can be obtained with a uniform applied pressure load on the entire surface by reducing the width of the negative electrode container flange 2 as shown in FIG.

However, since the area as an effective strength member becomes small, for example, when an axial force F acts on the flange as shown in FIG. 16, the stress generated at the joint interface becomes large and the corrosion strength against sodium corrosion and interfacial peel strength is increased. There is a disadvantage that reliability is lowered.

According to the present invention, the area of the bonding interface is large,
Since the nominal stress with respect to the axial force can be reduced, the strength reliability with respect to the interfacial strength can be improved.

In the case where the present invention is adopted, when the projection is provided on the negative electrode container flange and the insulating ring, it is possible to judge whether or not the present invention is adopted by these structures, and the intermediate material is processed. When the present invention is adopted by providing the protrusion (or taper), as shown in FIG. 17, the amount of protrusion of the intermediate material to the inside becomes larger than the amount of protrusion of the intermediate material to the outside at the time of hot pressing. Therefore, it is possible to determine whether or not the present invention is adopted by observing the cross section of the intermediate material.

FIG. 18 shows the protruding shape of the intermediate material in the case where the entire surface is heat-pressed with a uniform applied pressure, and the protruding amounts on the inner side and the outer side of the intermediate material are substantially the same.

[0047]

According to the present invention, it is possible to locally increase the pressure applied to the sodium-side end of the negative-side heat-pressure-welded portion by the heat-pressure welding, so that the sodium corrosion strength can be improved and the strength reliability can be improved. An improved sodium-sulfur battery is obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a main part of an embodiment of a sodium-sulfur battery according to the present invention.

FIG. 2 is a partial cross-sectional view showing the overall configuration of a sodium-sulfur battery that is the subject of the present invention.

FIG. 3 is a cross-sectional view showing the configuration of the main parts of a modified example of the embodiment of the sodium-sulfur battery according to the present invention shown in FIG.

FIG. 4 is an explanatory diagram showing actions and effects of the sodium-sulfur battery according to the present invention.

FIG. 5 is a cross-sectional view showing a configuration of a main part of another embodiment of the sodium-sulfur battery according to the present invention.

6 is a cross-sectional view showing the configuration of the main parts of a modification of the embodiment of the sodium-sulfur battery according to the present invention shown in FIG.

7 is a cross-sectional view showing the configuration of the main parts of another modification of the embodiment of the sodium-sulfur battery according to the present invention shown in FIG.

8 is a cross-sectional view showing the configuration of the main parts of another modification of the embodiment of the sodium-sulfur battery according to the present invention shown in FIG.

9 is a cross-sectional view showing the configuration of the main parts of another modification of the embodiment of the sodium-sulfur battery according to the present invention shown in FIG.

FIG. 10 is a cross-sectional view showing a configuration of a main part of another embodiment of the sodium-sulfur battery according to the present invention.

11 is a cross-sectional view showing the configuration of the main parts of a modified example of the embodiment of the sodium-sulfur battery according to the present invention shown in FIG.

FIG. 12 is a cross-sectional view showing a configuration of a main part of another embodiment of the sodium-sulfur battery according to the present invention.

FIG. 13 is a cross-sectional view showing a configuration of a main part of another embodiment of the sodium-sulfur battery according to the present invention.

FIG. 14 is a diagram showing an applied pressure distribution in a negative pressure side heat press contact portion of the sodium-sulfur battery according to the present invention.

FIG. 15 is an explanatory diagram showing an example of a case where uniform pressure is applied to the front surface of the sodium-sulfur battery at the negative pressure side heat press contact portion.

FIG. 16 is an explanatory diagram showing another zero in the case where uniform pressure is applied to the front surface of the negative pressure side hot press contact portion of the sodium-sulfur battery.

FIG. 17 is an explanatory view showing a state after heat pressure welding in the negative pressure side heat pressure welding portion of the sodium-sulfur battery according to the present invention.

FIG. 18 is an explanatory view showing a state after heat pressure welding in a negative pressure side heat pressure welding portion of a sodium-sulfur battery to which the present invention is not applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulation ring 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 Intermediate material side protrusion 13 Insulation ring side protrusion 14 Negative electrode Container flange side stopper 15 Insulating ring side stopper 16 Negative electrode container flange side protrusion 17 Negative electrode container flange side taper 18 Intermediate material side taper 19 Insulating ring side taper

Front Page Continuation (72) Inventor Hiroshi Sugiyama 3-1-1, Saiwaicho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Hisamitsu Hato 3-1-1, Saiwaicho, Hitachi City, Ibaraki Prefecture No. 1 within Hitachi Factory, Hitachi, Ltd. (72) Inventor Shigeru Sakaguchi 3-1, 1-1, Saiwaicho, Hitachi City, Ibaraki Inside Hitachi Factory, Hitachi, Ltd.

Claims (11)

[Claims] 1. A sodium-conducting solid electrolyte tube is provided between a negative electrode container containing sodium as a negative electrode active material and a positive electrode container containing sulfur as a positive electrode active material.
In a sodium-sulfur battery configured to heat-press the negative electrode container flange and the positive electrode container flange to an insulating ring joined to the solid electrolyte tube via an intermediate material, the heat at the sodium side end of the negative electrode side heat-pressing part A sodium-sulfur battery characterized in that a pressure increasing means for locally increasing the pressure applied by pressure is provided. 2. As the pressure increasing means, a projection is provided on the sodium-side end portion of the lower surface of the negative electrode container flange which is in contact with the intermediate material, and the negative electrode container flange having the projection is provided on the insulating ring through the intermediate material. The sodium-sulfur battery according to claim 1, wherein the sodium-sulfur battery is heat-pressed. 3. As the pressure increasing means, the plate thickness of the negative electrode container flange in contact with the intermediate material is tapered so that the sodium side end of the negative electrode container flange becomes thicker, and the negative electrode container flange having the taper is formed. The sodium-sulfur battery according to claim 1, wherein the insulating ring is heat-pressed through an intermediate material. 4. As the pressure increasing means, a projection is provided so that the plate thickness of the intermediate material becomes thicker at the sodium side end, and the negative electrode container flange is attached to the insulating ring through the intermediate material having the projection. The sodium-sulfur battery according to claim 1, wherein the sodium-sulfur battery is heat-pressed. 5. As the pressure increasing means, a taper is provided so that the plate thickness of the intermediate material becomes thicker at the sodium side end, and the negative electrode container flange is attached to the insulating ring through the intermediate material having the taper. The sodium-sulfur battery according to claim 1, wherein the sodium-sulfur battery is heat-pressed. 6. As the pressure increasing means, a protrusion is provided so that the thickness of the insulating ring in contact with the intermediate member becomes thicker at the sodium side end, and the insulating ring having the protrusion is provided with the intermediate member via the intermediate member. The sodium-sulfur battery according to claim 1, wherein the negative electrode container flange is heat-pressed. 7. The pressure increasing means is provided with a taper so that the thickness of the insulating ring in contact with the intermediate member is increased at the sodium side end, and the insulating ring having the taper is provided with the intermediate member via the intermediate member. The sodium-sulfur battery according to claim 1, wherein the negative electrode container flange is heat-pressed. 8. The sodium-sulfur battery according to claim 1, wherein the insulating ring is made of α-alumina, and the intermediate material is made of aluminum. 9. The sodium according to claim 1, wherein the insulating ring is made of α-alumina, and the intermediate material is made of an aluminum alloy.
Sulfur battery. 10. The sodium-sulfur battery according to any one of claims 1 to 8, wherein the negative electrode container flange and the intermediate material are integrally molded of aluminum. 11. The sodium-sulfur battery according to claim 1, wherein the negative electrode container flange and the intermediate material are integrally molded of an aluminum alloy.