JP2003243024A - Sodium - sulfur battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sodium - sulfur battery with high durability and high reliability. <P>SOLUTION: This sodium - sulfur battery is constituted by housing sodium in an anode chamber partitioned with a cylindrical solid electrolyte tube with bottom, an insulating ring 1 joined with the outer circumferential surface of an opening end part of the solid electrolyte tube, cathode fittings 2 joined with the top surface of the insulating ring 1, and an anode cover welded to the anode fittings 2. The anode fittings 12 are made of aluminum or an aluminum alloy, have such a shape that an outer flange part 2b is formed midway in a cylindrical part, and are joined with the top surface of the insulating ring 1 on the bottom of the outer flange part 2b, and a ring-shaped ceramic determent body 3 deterring a move repeatedly declining an anode fittings cylinder part 2a caused by thermal expansion and contraction in the operation of the battery is installed on the outer circumferential surface of the anode fittings cylinder part 2a in a non-joining state, and the bottom surface of the ceramic determent body 3 is joined by applying thermal pressure with the top surface of the outer flange part 2b. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD [0001] The present invention relates to a sodium-sulfur battery used as a secondary battery for power storage or the like, which alleviates fatigue deterioration of a cathode metal fitting due to a thermal cycle, and joins the cathode metal fitting and an insulating ring. The present invention relates to a sodium-sulfur battery characterized by being provided with a low-cost ceramic restraining body which prevents sodium from entering due to peeling of the surface.

[0002]

2. Description of the Related Art A sodium-sulfur battery is used in a power storage system for realizing functions such as power leveling and peak cut. The structure of the sodium-sulfur battery is shown in FIG. Is as schematically shown.

The battery structure at the time of manufacturing is such that a bottomed cylindrical beta-alumina solid electrolyte tube 9 is glass-bonded to the inner peripheral surface of the α-alumina insulating ring 1 at its upper outer peripheral surface, and further, the insulating ring 1 Cathode fitting 2 joined to the upper surface
And a cathode chamber defined by the cathode lid 4 welded to the cathode metal fitting 2, the insulating ring 1, and the beta-alumina solid electrolyte tube 9 has a bottomed cylindrical metal safety tube 12 and sodium inside the safety tube 12. And a sodium container 13 containing a small amount of sodium azide, and the anode chamber has an anode metal fitting 20 joined to the lower surface of the insulating ring 1,
Anode mat 10 welded to the anode fitting 20, a bottom lid 11 welded to the anode container 10, an insulating ring 1, and a beta-alumina solid electrolyte tube 9 are partitioned by a carbon mat impregnated with sulfur. Is provided, and an upper portion thereof is filled with an inert gas such as nitrogen.

After the unit cell is assembled by each member, sodium in the sodium container 13 is melted during the temperature rising process up to the battery operating temperature, and the sodium azide contained in the upper part of the sodium container 13 is decomposed. Due to the pressure of the generated nitrogen gas, the molten sodium flows into the cathode chamber through a small hole provided at the bottom of the sodium container 13 to fill the cathode chamber.

The battery operates at a temperature of 290 ° C. to 385 ° C., sodium ion-conducts as sodium ions in the beta-alumina solid electrolyte tube 9, reacts with molten sulfur in the anode chamber, generates sodium polysulfide, and discharges. The reaction proceeds. The opposite reaction proceeds during charging, and molten sodium is returned to the cathode chamber.

In the sodium-sulfur battery having the above-described structure, the insulating ring 1 made of α-alumina and the cathode metal fitting 2 made of Al or Al alloy, which are the constituent members, are thermocompression-bonded to each other to assemble a unit cell.

FIG. 7 shows a sectional view of a main part of the thermocompression bonding member. The thermo-compression bonding method of the insulating ring 1 and the cathode metal fitting 2 is performed by placing a ring-shaped metal-ceramic bonding member 17 on the upper surface of the insulating ring 1 and then inserting the cathode metal fitting 2 into the insulating ring 1 to form the cathode metal fitting. The bottom surface of the second outer flange 2b is brought into contact with the upper surface of the metal-ceramic joining member 17. Then, the stainless steel ring plate 18 is inserted and placed on the upper surface of the outer flange portion 2b of the cathode fitting 2. The outer flange portion 2b of the cathode fitting 2 is pressure-bonded to the upper surface of the insulating ring 1 by the pressing jig 19 in a heated furnace atmosphere.

At this time, the outer flange portion 2 b of the cathode fitting 2
Since it is an Al alloy, it is soft and is thermocompression bonded to the upper surface of the insulating ring 1 while being stretched together with the metal-ceramic bonding member 17. The gap between the insulating ring 1 located above the inner peripheral surface of the insulating ring 1 and the lower cylindrical portion 2c of the cathode fitting 2 is filled with a metal-ceramic joining member 17 that protrudes during pressurization.

After the thermocompression bonding, the pressing jig 19 is attached to the cathode fitting 2.
Since the stainless steel ring plate 18 and the pressing jig 19 are not joined to each other when detached from, the pressing jig 19 can be easily detached. On the other hand, the stainless steel ring plate 18 is in a state of being bonded to the cathode metal fitting 2, and as shown in FIG. 8, the stainless steel ring plate 18 remains in a state of being bonded to the outer flange portion 2b of the cathode metal fitting 2. After that, as shown in FIG. 9, the cathode lid 4 was welded to the upper edge of the cathode fitting 2 and assembled into a battery.

The stainless ring plate 18 is the pressing jig 1
The purpose of the present invention is only to improve the releasability of the SUS304 from 9 and the present inventors have used the SUS304 ring plate 18 having a thickness of 0.12 mm to 0.2 mm from the economical viewpoint. After the battery is assembled, it has no function and is a useless member for the battery.

The unit cells thus assembled were operated as an assembled battery for 7 years, and the batteries after 7 years of operation were disassembled and investigated and analyzed. As a result, as shown in FIG.
A minute crack is generated at a point B near the bent portion from the cylindrical portion 2a of the cathode fitting 2 to the outer flange portion 2b, and sodium is not penetrated into the joint at the point A near the upper end of the inner peripheral surface of the insulating ring 1. Had occurred. FIG. 12 shows a partially enlarged sectional view. A minute crack generated at a point B near the bent portion from the cylindrical portion 2a of the cathode metal fitting 2 to the outer flange portion 2b enters in a diagonally downward direction, and the cathode metal fitting 2 is near the upper end of the inner peripheral surface of the insulating ring 1. At the point A, it separated slightly upward, and sodium infiltration was observed in the thermocompression bonded portion between the cathode metal member 2 and the insulating ring 1. The cathode metal fitting 2 used is a cold forged aluminum alloy product, and the cylindrical portion and the outer flange portion are integrated.

The cause of occurrence of such a minute crack at the point B near the bent portion and the detachment of the cathode metal fitting 2 at the point A near the upper end of the inner peripheral surface of the insulating ring 1 and the accompanying intrusion of sodium are as follows. The expansion coefficient of the alumina insulating ring 1 is 7 to 8 × 10 ⁻⁶ / ° C., whereas the aluminum alloy cathode fitting 2 and the cathode lid 4 are 25 to 26 × 10 ⁻⁶ / ° C.
The difference is extremely large with ℃, the temperature rise and fall during the thermocompression bonding of the cathode fitting and the insulating ring, and the temperature rise during battery startup,
During the heat cycle of temperature increase / decrease due to charging and discharging during battery operation, further temperature decrease to room temperature and temperature increase to operating temperature at the time of periodic inspection and repair, the cathode metal fitting 2 cylindrical portion 2a is accompanied by the temperature change. Expands and contracts, but insulation ring 1
The cylindrical portion 2c inserted into the inside is constrained by the insulating ring 1 having a small coefficient of thermal expansion, and the movement of expansion and contraction is suppressed.

As a result, it is estimated that the cathode metal fitting cylindrical portion 2a repeatedly tilts from the point B near the bent portion of the cathode fitting 2 as a starting point, causing metal fatigue at the point B near the bent portion, and as a result, a crack is generated. It It is also presumed that the detachment of the cathode metal fitting 2 at the point A near the upper end of the inner peripheral surface of the insulating ring 1 is due to the same factor. As the size of the battery increases, the outer diameter and height of the cylindrical portion of the cathode fitting increase, and this problem tends to occur.

Japanese Unexamined Patent Publication (Kokai) No. 3-187160 proposes an invention in which a ring-shaped α-alumina deterrent body is brought into contact with the outer peripheral surface of the cylindrical portion of the cathode fitting, but a ring-shaped α-alumina deterrent body is proposed. Has an alumina content of 99% or more, which is extremely expensive in itself, and requires high dimensional accuracy for contact with the cylindrical portion of the cathode fitting, and the ring-shaped α-
Since the alumina restraining body has high strength, its polishing cost is also extremely high. Furthermore, in this conventional technique, after the cathode metal fitting and the α-alumina insulator are thermocompression bonded, a ring-shaped α-alumina restraining body is fitted into and abutted on the cylindrical portion of the cathode metal fitting. In this case, there is no solution to the strain stress in the bent portion B of the cathode metal fitting, which occurs when the insulating ring and the cathode metal fitting are thermocompression bonded.

Further, even when the battery is in operation, the α-alumina restraining member also moves following the tilting movement of the cathode fitting cylindrical portion, and the function of restraining the tilting of the cathode fitting cylindrical portion deteriorates.

Therefore, the present inventors have used a low-purity alumina ceramic deterrent body having a low alumina content as a relatively low-cost ceramic, and inserted this low-purity alumina ceramic deterrent body into the cathode fitting cylindrical portion, The insulating ring, the cathode fitting, and the low-purity alumina ceramic deterrent body were attempted to be hot-press bonded, but as shown in FIG. 13, cracks 2 started from the K point of the low-purity alumina ceramic deterrent body 3 after the hot-press bonding.
4 has occurred.

The present inventors have made detailed observations and investigations on the cause of cracking in the low-purity alumina ceramic deterrent body 3, and even if the ceramic deterrent body has a low alumina content and a low cost, During thermocompression bonding, no cracks will be generated in this ceramic restraining body, and no cracks will be generated in the cathode metal fittings even during long-term operation of the battery. Further, Na will also invade the thermocompression bonding surface between the insulating ring and the cathode metal fittings. The present invention has been completed by developing a sodium-sulfur battery that does not.

[0018]

Therefore, the object of the present invention is that in the thermocompression bonding process, cracks do not occur in the ceramic restraining body of low-purity alumina, and even if it is operated for a long time as a battery, There is no crack in the cathode fitting,
Further, it is intended to provide a sodium-sulfur battery which is low in cost, high in quality, and excellent in long-term durability and reliability, in which sodium does not invade the joint between the cathode fitting and the insulating ring.

[0019]

According to a first aspect of the present invention, a cylindrical solid electrolyte tube with a bottom, an insulating ring joined to an outer peripheral surface of an opening end of the solid electrolyte tube, and an upper surface of the insulating ring are provided. Sodium is stored in the cathode chamber defined by the joined cathode fitting and the cathode lid welded to the cathode fitting, while
Sulfur is stored together with an electronic conductive material in an anode chamber defined by an outer peripheral surface of a solid electrolyte tube, an insulating ring, and an anode fitting joined to the bottom surface of the insulating ring and a cylindrical anode container welded to the anode fitting. In a sodium-sulfur battery,
The cathode metal fitting is made of aluminum or an aluminum alloy, and the shape is such that the outer flange portion is in the middle of the cylindrical portion, and the cathode metal fitting is joined to the upper surface of the insulating ring at the bottom surface of the outer flange portion. A ring-shaped ceramic restraining body that suppresses the repeated tilting movement of the cathode metal fitting cylindrical portion due to thermal expansion and contraction is provided in a state not bonded to the outer peripheral surface of the cathode metal fitting cylindrical portion, and the ceramic restraining body There is provided a sodium-sulfur battery, wherein the bottom surface is thermocompression bonded to the upper surface of the outer flange portion.

In the present invention, it is preferable that the ceramic restraining body is arranged with a gap provided between the ceramic restraining body and the outer circumferential surface of the cathode fitting cylindrical portion. Is even more preferable.

Further, in the present invention, it is preferable that the ceramic restraining member is provided in a state of abutting on or in proximity to a cathode metal fitting cylindrical portion whose outer peripheral surface is covered with an oxide film.

Further, in the present invention, it is preferable that the ceramic restraining body is provided in contact with or close to the outer peripheral surface of the cathode fitting cylindrical portion via a ring-shaped stainless steel cylindrical body. The stainless steel cylinder has a flange on the lower edge, and the bottom of the flange is pressure-bonded to the upper surface of the outer flange of the cathode fitting, and the upper surface of the flange is heat-pressure bonded to the bottom of the ceramic restrainer. Is more preferable.

Further, according to the second aspect of the present invention, a cylindrical solid electrolyte tube having a bottom, an insulating ring joined to the outer peripheral surface of the open end of the solid electrolyte tube, and a cathode joined to the upper surface of the insulating ring Sodium is stored in the cathode chamber defined by the metal fitting and the cathode lid welded to the cathode metal fitting, while it is welded to the anode metal fitting and the anode metal fitting joined to the outer peripheral surface of the solid electrolyte tube, the insulating ring and the bottom surface of the insulating ring. In a sodium-sulfur battery in which sulfur is stored together with an electronic conductive material in an anode chamber partitioned with a cylindrical anode container, the cathode metal fitting is made of aluminum or an aluminum alloy, and the shape thereof is a cylindrical portion. A cathode metal fitting having a shape having an outer flange part in the middle and joined to the upper surface of the insulating ring at the bottom surface of the outer flange part, and a cylinder of the cathode metal fitting in contact with the ring-shaped ceramic restrainer. Sodium-sulfur, characterized in that the entire outer peripheral surface of the portion is pressure-bonded to the inner peripheral surface of the ring-shaped ceramic restraining body, and the bottom surface of the ceramic restraining body is thermocompression-bonded to the upper surface of the cathode metal fitting outer flange portion. Batteries are provided.

In the first and second inventions of the present invention, a low-purity alumina ceramics material can be used as the ring-shaped ceramic restrainer, and a low-purity alumina ceramics material having a purity of 70% or more can be used. It can also be used.

[0025]

Embodiments of the present invention will be described below, but it goes without saying that the present invention is not limited to the following embodiments. The sodium-sulfur battery of the first invention (claim 1) of the present invention will be described. The feature of the sodium-sulfur battery of the first invention of the present invention is that the ring-shaped ceramic restraining body for restraining the movement of the cathode fitting cylindrical portion repeatedly tilted by thermal expansion and contraction during battery operation is the outer peripheral surface of the cathode fitting cylindrical portion. And the bottom surface of the ceramic restraining body is thermocompression bonded to the top surface of the outer flange portion.

Due to this feature, cracks do not occur in the ring-shaped ceramic restraining body 3 during the thermocompression bonding process, and the cathode metal fitting cylindrical portion 2a is caused by thermal expansion and contraction during battery operation.
Prevents repeated tilting movements. Even if the battery is operated for a long period of time, no crack is generated in the bent portion B of the cathode metal fitting 2, and Na is prevented from entering the thermocompression bonding surface 6 of the insulating ring 1 and the cathode metal fitting 2. A special effect can be obtained.

The present invention will be sequentially described below based on preferred specific embodiments. FIG. 1 is a diagram showing a preferred embodiment 1 of the present invention. That is, FIG. 1 shows a battery element after assembly using an insulating ring 1 made of α-alumina, which is a constituent member of the sodium-sulfur battery of the present invention, a cathode metal fitting 2, and a ring-shaped ceramic restraining body 3. The expanded sectional view of a part is shown. The shape of the cathode fitting 2 is a cylindrical part (the upper part is 2
It is a shape having an outer flange portion 2b in the middle of (a, the lower part is denoted by 2c), and is an integrated product of aluminum or aluminum alloy manufactured by cold forging.

The feature of the sodium-sulfur battery of the first embodiment is that the gap S is large enough to prevent the cathode fitting cylindrical portion 2a from repeatedly tilting due to thermal expansion and contraction during battery operation.
And the ring-shaped ceramic restraining body 3 is disposed near the outer peripheral surface of the cathode fitting cylindrical portion 2a, and the bottom surface of the ceramic restraining body 3 is thermocompression bonded to the upper surface of the outer flange portion 2b. It is characterized by that.

During thermocompression bonding, the upper part of the aluminum alloy cathode metal fitting cylindrical portion 2a greatly expands during the temperature rising process,
On the other hand, the lower part of the cylindrical portion 2a is restrained by the low expansion α-alumina insulating ring 1 to suppress the expansion. As a result, the cylindrical portion 2a of the cathode fitting 2 spreads upward in a trumpet shape, and the stress that pushes the ring-shaped ceramic restraining body 3 provided on the outer peripheral surface of the cylindrical portion 2a acts on the ceramic restraining body 3. .

However, since the gap S is provided between the outer peripheral surface of the cylindrical portion 2a and the ring-shaped ceramic restraining member 3, the ceramic restraining member is not affected by the expansion and contraction of the cylindrical portion 2a. No local strain stress is generated in the body 3, and the stress that spreads the ceramic restraining body 3 is relaxed, so that the ceramic restraining body 3 is not cracked. Even when assembled as a battery and operated for a long time, the cathode metal fitting 2
A crack is not generated in the bent portion B of No. 1, and Na is prevented from entering the thermocompression bonding surface 6 of the insulating ring 1 and the cathode fitting 2.

The bottom surface of the ring-shaped ceramic restraining body 3 is thermocompression-bonded to the upper surface of the outer flange portion 2b of the cathode fitting 2 which is thermocompression-bonded to the insulating ring 1. It is integral with the insulating ring 1.

If the ring-shaped ceramic restraining body 3 is not thermocompression bonded to the upper surface of the outer flange portion 2b, the ring-shaped ceramic restraining body 3 follows the tilting movement of the cathode metal fitting cylindrical portion 2a due to thermal expansion and contraction during battery operation. Ceramic deterrent body 3
Also, the function of restraining the tilting of the cathode fitting cylindrical portion 2a is deteriorated.

The gap S that prevents the cathode fitting cylindrical portion from repeatedly tilting due to thermal expansion and contraction during battery operation depends on the shape and size (battery capacity) of the battery, that is, outside the cathode lid 4 of the cathode fitting. The diameter is appropriately set according to the height of the cylindrical portion 2a.

As Embodiment 2 of the present invention, as shown in FIG. 2, it is preferable that the gap S continuously increases toward the upper side. This is because the stress acting on the ceramic restraining body 3 from the cathode fitting 2 is dispersed. That is, the upper side of the cylindrical portion 2a of the cathode fitting expands greatly in the lateral direction, and the upper side of the ceramic restraining body 3 receives a large stress, but the gap S is continuously set higher toward the upper side. This is because the occurrence of local strain stress acting on the body 3 is prevented.

Next, another preferred embodiment 3 of the present invention
Will be described. The feature of Embodiment 3 of the present invention is that FIG.
As shown in FIG. 3, the oxide film 1 is formed on the entire outer peripheral surface of the cathode metal fitting cylindrical portion 2a that is in contact with or close to the ring-shaped ceramic restraining body 3.
4 and is not bonded to the inner peripheral surface of the ring-shaped ceramic restraining body 3, and the bottom surface of the ceramic restraining body 3 is thermocompression bonded to the upper surface of the outer flange portion 2b of the cathode fitting 2. It is a point.

If the entire outer peripheral surface of the cylindrical portion 2a of the cathode fitting 2 that is in contact with or close to the inner peripheral surface of the ring-shaped ceramic restraining body 3 is not cut and the surface is made into an oxide film layer, thermal compression is performed. At the time of joining, the contact surface 8 between the outer peripheral surface of the cylindrical portion 2a of the cathode fitting and the inner peripheral surface of the ring-shaped ceramic restraining body 3 is in a non-bonding (non-pressure bonding) state over the entire area. No crack occurs in 3. In addition, after the thermocompression bonding, the ring-shaped ceramic restraining body 3 is brought into contact with or in the vicinity of the cathode fitting cylindrical portion 2a in the temperature lowering process.

The ring-shaped ceramic restraining body 3 is provided in a state of abutting or in proximity to the cathode metal fitting cylindrical portion 2a whose outer peripheral surface is covered with an oxide film, and the bottom surface of the ceramic restraining body 3 is an insulating ring. Since the upper surface of the outer flange portion 2b of the cathode metal fitting 2 that is heat-pressure-bonded to No. 1 is heat-pressure-bonded, cracks do not occur in the ring-shaped ceramic restraining body 3 during the heat-pressure bonding process, and Even if the battery is operated for a long period of time, cracks do not occur in the cathode metal fitting 2 and, further, Na is prevented from entering the thermocompression bonding portion between the insulating ring 1 and the cathode metal fitting 2.

Next, still another preferred embodiment 4 of the present invention will be described. The feature of Embodiment 4 of the present invention is that
As shown in FIG. 4, a ring-shaped ceramic restraining body 3 for restraining the tilting movement of the cathode metal fitting cylindrical portion 2a due to thermal expansion and contraction during battery operation is made of ring-shaped stainless steel on the outer peripheral surface of the cathode metal fitting cylindrical portion 2a. The point is that they are provided in contact with or close to each other via the cylindrical body 15, and that the bottom surface of the ceramic restraining body 3 is thermocompression bonded to the upper surface of the outer flange portion 2b of the cathode fitting 2.

When the insulating ring 1, the outer flange portion 2b of the cathode metal fitting 2 and the ceramic restraining body 3 are thermocompression bonded, a ring-shaped stainless steel cylindrical body 15 is interposed between the cathode metal fitting 2 and the ceramic restraining body 3. By doing so, the ring-shaped stainless steel cylindrical body 15 suppresses the expansion of the cathode fitting cylindrical portion 2a during the temperature rising process, and the stress acting on the ceramic suppressing body 3 is relieved. Further, the stainless cylindrical body 15 and the ceramic restraining body 3 are not joined. Therefore, cracks do not occur in the ceramic restraining body 3 in the hot press bonding step.

Further, the repeated tilting movement of the cathode fitting cylindrical portion 2a due to thermal expansion and contraction during battery operation is suppressed by both the stainless steel cylindrical body 15 and the ceramic restraining body 3, and the ceramic restraining body 3 is also provided. Since the bottom surface of the cathode metal fitting is thermocompression bonded to the upper surface of the outer flange portion 2b of the cathode metal fitting 2, even if the battery is operated for a long period of time, no crack is generated in the bent portion B of the cathode metal fitting 2 and the insulating ring is formed. It is also possible to prevent Na from entering the thermocompression bonding surface 6 of the cathode metal 1 and the cathode metal fitting 2.

As a further preferred embodiment 5 of the present invention, as shown in FIG.
Has a flange portion 15a at the lower edge, and the flange portion 1
The bottom surface of 5a is preferably pressure-bonded to the upper surface of the outer flange portion 2b of the cathode fitting 2.

The stainless steel ring cylinder 15 has a flange portion 15a at the lower end edge, and the flange portion 15a
Since the bottom surface of the above is pressure-bonded to the upper surface of the outer flange portion 2b of the cathode fitting 2 and the bottom surface of the ceramic restraining body 3 is thermocompression bonded to the upper surface of the flange portion 2a, the insulating ring 1 and the cathode fitting are Outer flange 2b, stainless steel cylindrical flange 15a, and ceramic restraining body 3
And are integrally joined. This further reliably prevents the cathode fitting cylindrical portion 2a from repeatedly moving due to thermal expansion and contraction during battery operation.

The ring-shaped stainless steel cylindrical body 15
Is made of austenitic stainless steel (S
US304) may be used, but a material having a thermal expansion coefficient close to that of the α-alumina insulating ring and high rigidity is preferable. For example, ferritic stainless steel (eg SUS430)
The coefficient of thermal expansion of 11 × 10 ⁻⁶ / ° C. is inexpensive and is particularly preferable.

The battery structure of the other components constituting the sodium-sulfur battery of the first invention of the present invention is the same as the sodium-sulfur battery shown in FIG. That is, after the cathode metal fitting 2 is thermocompression-bonded to the insulating ring 1, a bottomed tubular safety tube 12 made of metal and a sodium container 1 containing sodium and a small amount of sodium azide inside the safety tube 12
3, the cathode lid 4 is welded to the cathode fitting 2 in a reduced pressure atmosphere.

Regarding the anode chamber, the anode metal fitting 20 is thermocompression bonded to the bottom surface of the insulating ring 1, and the outer peripheral surface of the upper end portion of the bottomed cylindrical beta alumina solid electrolyte tube 9 is glass bonded to the inner peripheral surface of the insulating ring 1. Then, the anode metal fitting 20 has a cylindrical anode container 1
After welding 0, a carbon mat (electronic conductive material) impregnated with sulfur is placed in the anode positive vessel 10, and then the bottom lid 11 is welded to assemble the battery.

Next, the sodium-sulfur battery of the second invention (claim 7) of the present invention will be explained. Second of the present invention
The feature of the sodium-sulfur battery of the invention is, as shown in FIG. 6, the cathode metal fitting 2 in contact with the ring-shaped ceramic restraining body 3.
The entire outer peripheral surface of the cylindrical portion 2a is pressure-bonded to the inner peripheral surface of the ring-shaped ceramic restraining body 3, and the ceramic restraining body 3
Is the point where the bottom surface of is bonded to the upper surface of the outer flange portion 2b of the cathode fitting 2 by thermocompression.

Since the bottom surface of the ceramic restraining body 3 is heat-pressure joined to the upper surface of the outer flange portion 2b of the cathode fitting 2 that is heat-pressure joined to the insulating ring 1, the ceramic restraining body 3 is a cathode fitting cylinder. The portion 2a does not follow the tilting movement, and the ring-shaped ceramic restraining body 3 is pressure-bonded to the outer peripheral surface of the cathode fitting cylindrical portion 2a, so that thermal expansion and contraction during battery operation. This prevents the cathode fitting cylindrical portion 2a from repeatedly tilting. No cracks are generated in the ring-shaped ceramic restraining body 3 even in the hot press bonding step. Even when assembled as a battery and operated for a long period of time, cracks do not occur in the bent portion B of the cathode fitting 2, and Na is prevented from entering the thermocompression bonding surface 6 between the insulating ring 1 and the cathode fitting 2. It

Since the ring-shaped ceramic restraining body 3 is pressure-bonded to the ground outer peripheral surface of the cathode metal fitting cylindrical portion 2a over the entire area, a ring-shaped ceramic restraining body is used during thermocompression bonding. The mechanism by which cracks do not occur in 3 will be described. In the conventional case shown in FIG. 13, cracks 24 are generated in the ring-shaped ceramic restraining body 3 at the time of thermocompression bonding. As a result of observation and inspection, it was found that the cracks 24 were generated from the boundary line K point of the contact / non-contact of the ring-shaped ceramic restraining body 3 to the outer peripheral surface of the cylindrical portion 2a of the cathode fitting 2. .

A boundary line K between the contact surface and the non-contact surface of the aluminum alloy cathode metal fitting 2 manufactured by cold forging.
As a result of investigating and observing the points, as shown in FIG. 14, the non-contact surface 23 is the surface as produced by cold forging and is the surface portion having the oxide film, while the contact surface 22
Was a surface that was cut, and was found to be a surface portion without an oxide film. In the aluminum alloy cathode metal fitting 2 manufactured by cold forging, the lower portion of the cylindrical portion 2a has poor dimensional accuracy and requires grinding.

Causes of occurrence of this joint portion / non-joint portion,
And the cause of cracks at the boundary line K point,
The cylindrical portion 2a of the cathode metal fitting 2 is heated by heat during the thermocompression bonding.
Expands and a pressure is applied in a direction to strongly spread the low expansion ceramic restraining body 3, and as a result, the grinding surface 22 having no oxide film is pressure-bonded and the surface portion having the oxide film is not bonded (non-bonded). It is presumed that it has become a state of (crimping and joining). It is estimated that a large strain stress was generated at the boundary line K point between the contact surface 22 and the non-contact surface 23 when the cathode fitting 2 contracted during the temperature decrease to room temperature, and the crack 24 started from the K point. To be done.

Therefore, the inventors of the present invention set the entire outer peripheral surface of the cylindrical portion 2a of the cathode metal fitting 2 in contact with the ring-shaped ceramic restraining body 3 as a cut surface, so that the cathode metal fitting is heated in the temperature rising process during thermocompression bonding. The contact surface (bonding surface) 7 between the outer peripheral surface of the cylindrical portion 2a and the ring-shaped ceramic restraining body 3 is pressure-bonded to each other in the entire region, and no strain stress is locally generated even in the temperature lowering process, and the ring-shaped ceramic restraining body is formed. The second invention of the present invention has been completed on the assumption that no cracks will occur in No. 3.

Also in the sodium-sulfur battery of the second invention of the present invention, similar to the sodium-sulfur battery of the first invention, the battery structure by the other constituent members of the sodium-sulfur battery is shown in FIG. It is the same as the battery.

(Heat-Pressure Bonding Test) Thirty heat-pressure bonding bodies based on the first and second inventions of the present invention were manufactured as Examples 1 to 6. The presence or absence of cracks was inspected for the ring-shaped ceramic restraining body of each thermocompression bonded body, and the results are shown in Table 1.

As the ring-shaped ceramic deterrent body, a ring-shaped low-purity alumina ceramic deterrent body having a ring width of 5 mm and a thickness of 5 mm was used. The dimensions of the cylindrical portion of the cathode fitting are 60 mm in outer diameter, 13 mm in height, and 1.0 in wall thickness.
An aluminum alloy having a size of mm was used. The ring-shaped stainless steel cylinder used in Examples 4 and 5 was made of SUS430 with a wall thickness of 0.5 mm.

The inspection method for the presence or absence of cracks in the ring-shaped low-purity alumina ceramic deterrent body is as follows: the X-ray transmission method, the penetrant flaw test method, and the specimen after the penetrant flaw test is cut and observed with an optical microscope. Confirmed by. At the same time, using a cathode fitting having a conventional non-polished surface and a polished surface shown in FIG. 14, a thermocompression bonded body produced by a conventional method was also observed for a ring body made of low-purity alumina ceramics. The results are shown in Table 1 as a conventional example.

[0056]

[Table 1]

No cracks were generated in the ring-shaped low-purity alumina ceramic deterrent bodies of the thermocompression bonded bodies (each of Examples 1 to 6) according to the first and second inventions of the present invention. On the other hand, the low-purity alumina ceramic ring body of the thermocompression bonded body manufactured by the conventional method has 3
28 of 0 had cracks.

[0058]

As described above, according to the sodium-sulfur battery of the first invention and the second invention of the present invention, the movement of the cathode fitting cylindrical portion repeatedly tilted due to thermal expansion and contraction during battery operation is suppressed. Even if a low cost suppressor having a low alumina content is used as the ring-shaped ceramic suppressor, cracks do not occur in the ceramic suppressor in the thermocompression bonding process. In addition, even if a heat cycle is performed when the battery starts up, the temperature rises and falls due to charging and discharging during battery operation, and further, the temperature decreases to room temperature and temperature rises to the operating temperature during periodic inspection and repair. No cracks are generated in the metal fitting, and Na is prevented from entering the thermocompression bonding portion between the insulating ring and the cathode metal fitting. As a result, it is possible to obtain a sodium-sulfur battery that is low in cost and has excellent long-term durability and reliability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a battery local structure for explaining a preferred embodiment 1 of the present invention according to a sodium-sulfur battery of the first invention of the present invention.

FIG. 2 is a cross-sectional view of a main part of a battery local structure for explaining a further preferred embodiment 2 of the present invention according to the sodium-sulfur battery of the first invention of the present invention.

FIG. 3 is a cross-sectional view of an essential part of a battery local structure for explaining another preferred embodiment 3 according to the sodium-sulfur battery of the first invention of the present invention.

FIG. 4 is a fragmentary cross-sectional view of a battery local structure for explaining a further preferred embodiment 4 of the present invention according to the sodium-sulfur battery of the first invention of the present invention.

FIG. 5 is a fragmentary cross-sectional view of a battery local structure for explaining a further preferred embodiment 5 of the present invention according to the sodium-sulfur battery of the first invention of the present invention.

FIG. 6 is a cross-sectional view of a main part of a battery local structure for explaining an example of the embodiment of the present invention, which relates to the sodium-sulfur battery of the second invention of the present invention.

FIG. 7 is a cross-sectional view of a main part in which an insulating ring, a metal / ceramic bonding material, a cathode fitting, and a stainless steel ring plate are arranged and pressed by a pressing jig in a conventional thermocompression bonding process. Show.

FIG. 8 is a sectional view of a main part of a conventional intermediate battery member including an insulating ring after thermocompression bonding, a cathode fitting, and a stainless steel ring plate.

FIG. 9 is a cross-sectional view of an essential part for explaining assembling a battery by welding a cathode cover to a conventional cathode fitting.

FIG. 10 is a schematic cross-sectional view showing a conventional sodium-sulfur battery.

FIG. 11 is a diagram for explaining cracks that occur in a cathode metal fitting and infiltration of Na into a thermocompression bonding surface between the cathode metal fitting and the insulating ring when a conventional sodium-sulfur battery is operated for many years.

FIG. 12 is a locally enlarged cross-sectional view showing a cracked portion and a portion where Na enters the thermocompression bonding surface between the cathode fitting and the insulating ring.

FIG. 13 is a diagram illustrating a starting point of a crack that occurs in a ring-shaped ceramic body in a thermocompression bonding process.

FIG. 14 is a diagram illustrating a relationship between a positional relationship between a surface-ground portion and a non-ground portion of a conventional cathode fitting and a starting point of a crack generated in a ring-shaped ceramic body.

[Explanation of symbols]

1 ... Insulating ring, 2 ... Cathode metal fitting, 2a ... Upper cylindrical part, 2
b ... outer flange part, 2c ... lower cylindrical part, B ... bent part, 3
... Ring-shaped ceramic restraining body, S ... Gap, 4 ... Cathode lid, 5 ... Thermocompression bonding surface of cathode metal fitting outer flange and ceramic restraining body, 6 ... Thermocompression bonding surface of cathode fitting and insulating ring,
7 ... Joining surface between outer peripheral surface of cathode fitting cylindrical portion and inner peripheral surface of ceramic suppressor, 8 ... Contact surface between outer peripheral surface of cylindrical cylindrical cathode fitting and ceramic restricting inner peripheral surface (non-joint surface) ) 9 ... Solid electrolyte tube, 10 ... Anode container, 11 ... Bottom lid,
12 ... Safety pipe, 13 ... Sodium storage container, 14 ... Oxide film, 15 ... Ring-shaped stainless steel cylinder, 15a ...
Flange portion, 16 ... Joining surface between outer peripheral surface of cathode fitting cylindrical portion and stainless steel cylinder, 17 ... Metal-ceramic joining material, 18 ... Stainless ring plate, 19 ... Pressing jig, 2
0 ... Anode metal fitting, 21 ... Welded portion, 22 ... Grinding surface (contact surface), 23 ... Non-contact surface, 24 ... Crack, K ... Origin of crack occurrence.

Continued front page    (72) Inventor Mitsuhiro Shomura             2-56, Sudacho, Mizuho-ku, Nagoya-shi, Aichi             Inside Hon insulator Co., Ltd. F term (reference) 5H029 AJ05 AJ14 AK05 AL13 AM15                       BJ02 BJ16 CJ02 CJ03 CJ05                       DJ06 EJ01 EJ08 HJ01

Claims (9)

[Claims] 1. A bottomed cylindrical solid electrolyte tube, an insulating ring joined to the outer peripheral surface of the open end of the solid electrolyte tube, a cathode fitting joined to the upper surface of the insulating ring, and a welding to the cathode fitting. Sodium is contained in a cathode chamber defined by a cathode lid, while the outer peripheral surface of the solid electrolyte tube, the insulating ring, an anode fitting joined to the bottom surface of the insulating ring, and a cylindrical shape welded to the anode fitting. In a sodium-sulfur battery in which sulfur is stored together with an electronic conductive material in an anode chamber defined by the anode container, the cathode metal fitting is made of aluminum or an aluminum alloy, and its shape is in the middle of the cylindrical portion. A cathode metal fitting having a shape having an outer flange portion and joined to the upper surface of the insulating ring on the bottom surface of the outer flange portion, wherein the cathode metal fitting cylindrical portion is repeatedly subjected to thermal expansion and contraction during battery operation. A ring-shaped ceramic restraining body for restraining the moving motion is provided in a state of not being joined to the outer peripheral surface of the cathode metal fitting cylindrical portion, and the bottom surface of the ceramic restraining body is heated on the upper surface of the outer flange portion. A sodium-sulfur battery characterized by being pressure-bonded. 2. The sodium-sulfur battery according to claim 1, wherein the ceramic restraining member is arranged with a gap provided between the ceramic restraining member and the outer peripheral surface of the cathode fitting cylindrical portion. 3. The sodium-sulfur battery according to claim 2, wherein the gap is continuously provided so as to be larger toward the upper side. 4. The sodium according to claim 1, wherein the ceramic restraining member is provided in a state of abutting on or in proximity to the cathode metal fitting cylindrical portion whose outer peripheral surface is covered with an oxide film. Sulfur battery. 5. The ceramic suppressor is provided in contact with or close to the outer peripheral surface of the cathode fitting cylindrical portion via a ring-shaped stainless steel cylindrical body. Sodium-sulfur battery. 6. The stainless steel cylindrical body has a flange portion at a lower end edge thereof, a bottom surface of the flange portion is pressure-bonded to an upper surface of an outer flange portion of the cathode fitting, and the ceramic is provided on an upper surface of the flange portion. The sodium-sulfur battery according to claim 5, wherein the sodium-sulfur battery is thermocompression bonded to the bottom surface of the depressing body. 7. A bottomed cylindrical solid electrolyte tube, an insulating ring joined to the outer peripheral surface of the open end of the solid electrolyte tube, a cathode fitting joined to the upper surface of the insulating ring, and a welding to the cathode fitting. Sodium is contained in a cathode chamber defined by a cathode lid, while the outer peripheral surface of the solid electrolyte tube, the insulating ring, an anode fitting joined to the bottom surface of the insulating ring, and a cylindrical shape welded to the anode fitting. In a sodium-sulfur battery in which sulfur is stored together with an electronic conductive material in an anode chamber defined by the anode container, the cathode metal fitting is made of aluminum or an aluminum alloy, and its shape is in the middle of the cylindrical portion. A cathode metal fitting having a shape having an outer flange portion, the bottom surface of the outer flange portion being joined to the upper surface of the insulating ring, and the entire outer peripheral surface of the cylindrical portion of the cathode metal fitting in contact with the ring-shaped ceramic restraining body. Is the inner peripheral surface and the pressure bonding of the ring-shaped ceramic suppression body, and sodium bottom of the ceramic suppression body is characterized in that it is thermocompression bonded to the upper surface of the cathode metal outer flange - sulfur battery. 8. The sodium-sulfur battery according to claim 1, wherein the ring-shaped ceramic suppressor is made of low-purity alumina ceramics. 9. The sodium-sulfur battery according to claim 8, wherein the purity of the low-purity alumina ceramics is 70% or more.