JP3526229B2 - Bonding method and bonding structure of insulating ring and cathode metal fitting for sodium-sulfur battery - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sodium-sulfur battery that is preferably used as a secondary battery for power storage and the like, and more specifically, a junction between an insulating ring that is a constituent member of a sodium-sulfur battery and a cathode metal fitting. It relates <br/> the methods and coupling structure.

[0002]

2. Description of the Related Art A sodium-sulfur battery has a bottomed cylindrical solid electrolyte tube arranged in an anode container which is a storage case. Inside the solid electrolyte tube, sodium as a cathode active material is provided, and outside the solid electrolyte tube is provided. It has a structure containing sulfur as an anode active material, and is used in a state of being heated to 300 to 350 ° C. That is, ionized sodium permeates the solid electrolyte tube and reacts with sulfur to generate electricity when sodium polysulfide is generated, while the opposite reaction generates sodium and sulfur to charge the battery. It is a mechanism to do.

Such a sodium-sulfur battery has a cathode metal fitting for taking out generated electricity or sending electricity at the time of charging, but the cathode metal fitting is electrically insulated from the anode side. Since it is necessary to install it in, a connecting structure is generally adopted in which a hollow cylindrical insulating ring made of an insulating material such as α-alumina is thermocompression bonded.

For example, as shown in FIG. 2, the lower metal jig 40, the insulating ring 30, the bonding material 31,
A collar 32a formed on the outer peripheral surface of the hollow tube portion 32b of the cathode metal fitting 32 and an upper jig 39 are sequentially laminated, and preferably, the inner peripheral side of the cathode metal fitting 32 is warped to the inner peripheral side of the cathode metal fitting 32. The work is formed by loosely inserting the cylindrical jig 37 for preventing the above, and a vertical pressure is applied from one or both of the jigs 39 and 40 under high temperature conditions.

According to such a method, as shown in FIG. 3, the cathode fitting 32 has a collar portion 32 a formed on the outer peripheral surface thereof.
The lower end surface of the is firmly bonded to the upper end surface of the insulating ring 30 via the bonding material 31, and a bonding structure having high mechanical bonding strength in the vertical direction is formed. After the above thermocompression bonding, the jigs 37, 39, 40 are removed, and the bonded insulating ring 30 and cathode fitting 32 are loaded into an anode container (not shown) to assemble a sodium-sulfur battery.

[0006]

By the way, the coupling structure of the insulating ring 30 and the cathode fitting 32 is required to have not only the mechanical strength as described above but also corrosion resistance. That is, in the sodium-sulfur battery,
Since the bottomed cylindrical solid electrolyte tube filled with sodium metal is glass-bonded to the inner peripheral surface 41 on the lower end side of the insulating ring 30, the joint portion between the insulating ring 30 and the cathode fitting 32 is highly corrosive at high temperature. Because it will be exposed to sodium.

However, when the outer diameter of the hollow tube portion 32b of the cathode fitting 32 is increased with the recent increase in the size of the battery, a stronger peeling force is exerted on the coupling structure under heat cycle load than before. As a result, the corrosion resistance to sodium was reduced in the joint structure formed by the conventional thermocompression bonding method.

Specifically, due to thermal expansion, the cathode fitting 32
The gap 42 between the outer peripheral surface of the lower side of the collar portion 32a and the outer peripheral surface of the upper end side of the insulating ring 30 is peeled off, sodium penetrates and the joint portion is gradually corroded, so that the life of the sodium-sulfur battery is shortened. Was causing problems.

The present invention has been made in order to solve the problems of the prior art, and its object is to have high joint strength and high corrosion resistance to sodium.
An object of the present invention is to provide a method for joining an insulating ring of a sodium-sulfur battery and a cathode fitting and a joining structure.

[0010]

Means for Solving the Problems That is, according to the present invention, a cylindrical insulating ring having a hollow portion and a hollow tubular cathode having a collar portion formed on the outer peripheral surface thereof and capable of being fitted into the hollow portion Sodium for thermocompression bonding with metal fittings through a bonding material
A method for joining an insulating ring of a sulfur battery and a cathode fitting ,
By pressing from the vertical direction of the collar portion and the inner peripheral surface side of the cathode fitting, the lower surface of the collar portion and the upper end surface of the insulating ring, and the outer peripheral surface of the cathode fitting on the lower side of the flange portion and the inner peripheral surface of the insulating ring are continuous. The inner peripheral surface of the cathode metal fitting, the pressing from the inner peripheral surface side of the cathode metal fitting is performed by a cylindrical jig that can be fitted to the inner circumference of the cathode metal fitting. sodium clearance of the outer peripheral surface, characterized in that as is 30～170Myuemu - absolute sulfur battery
A method of joining the edge ring and the cathode fitting is provided.

[0011] The joining method of the present invention is preferably the outer circumferential surface of the inner circumferential surface of the negative electrode metal piece and the cylindrical jig is complementary taper.

Further, according to the present invention, there is provided a coupling structure between the insulating ring of the sodium-sulfur battery formed by the above-mentioned joining method and the cathode fitting.

[0013]

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, an insulating ring and a cathode fitting having a flange formed on the outer peripheral surface are pressed not only in the vertical direction of the flange but also from the inner peripheral surface side of the cathode fitting. Adopt a joining method. By adopting such a joining method, not only the lower surface of the collar portion and the upper end surface of the insulating ring, but also the outer peripheral surface of the cathode metal fitting on the lower side of the collar portion and the inner peripheral surface of the insulating ring are continuously connected with a large pressing force. Since they are joined together and the joining portion becomes long, the strength and corrosion resistance of the joining portion between the insulating ring and the cathode fitting are enhanced, and the life of the entire battery can be extended. Hereinafter, the present invention will be described in detail.

The joining method of the present invention adopts a joining method of pressing the flange portion of the cathode fitting from above and below as well as the conventional joining method, and also pressing from the inner peripheral surface side of the cathode fitting. Therefore, in addition to jigs such as the upper jig 39 and the lower jig 40 in FIG. 2 for applying pressure in the vertical direction, a means for pressurizing from the inner peripheral surface side of the cathode fitting to the outer peripheral direction is newly added. Will be needed. Specifically, the pressure can be applied from the inner peripheral side of the cathode metal fitting by a cylindrical jig that can be fitted into the inner peripheral surface of the cathode metal fitting.

In the present invention, the cylindrical jig is a metal jig that can be fitted into the inner peripheral surface of the cathode fitting, and it is preferable to use a hollow cylindrical jig. The hollow cylindrical jig is used for the purpose of facilitating the vacuum evacuation of the inside of the work and preventing the heat capacity from increasing because the thermocompression bonding is performed under a vacuum condition. On the other hand, if the cylindrical jig is solid, it becomes difficult to evacuate the inside of the work, and the heat capacity increases, which is not preferable.

Note that, even in the past, a cylindrical jig was sometimes loaded to prevent inward warping of the cathode fitting during hot-press bonding, but in the case of the present invention, it is positively applied from the inner peripheral surface side. It differs from this in that it is intended to be pressed. That is, in the conventional cylindrical jig, it suffices to prevent the inward warp of the cathode metal fitting, so that the clearance between the inner peripheral surface of the cathode metal fitting and the outer peripheral surface of the cylindrical jig is relatively large. The pressing force from the side could not be applied. Therefore, even if the bonding material flows into the gap between the outer peripheral surface of the cathode metal fitting on the lower side of the flange portion and the inner peripheral surface of the insulating ring during the thermocompression bonding, the portion cannot be firmly bonded.

[0018] For the reasons described above, in the present invention, for obtaining the pressing force from the cathode fitting inner circumferential surface side, that make up a small clearance between the outer peripheral surface of the cathode fitting inner circumferential surface of a cylindrical jig . Specifically, while the clearance between the previous cylindrical jig and the cathode metal was about 300 [mu] m, it shall be the 30~170μm in the present invention.

However, when the clearance is made too small, a cylindrical jig is inserted into the cathode fitting (hereinafter referred to as “assemblability”) and the jig is pulled out after the completion of thermocompression bonding ( Hereinafter, "removability") may be difficult.

Therefore, in order to improve the assemblability and the detachability of the jig, it is more preferable to adopt a method in which the inner peripheral surface of the cathode fitting and the outer peripheral surface of the cylindrical jig have complementary tapered shapes. That is, as shown in FIG. 4, the inner peripheral surface of the cathode fitting 12 is formed into a mortar shape, and the outer peripheral surface of the cylindrical jig 17 is formed into a truncated cone shape complementary to the inner peripheral surface. This is a method of applying vertical pressure.

According to this method, the vertical pressure applied to the cylindrical jig 17 by the jigs 19 and 20 is also converted to the horizontal pressure by the taper, so that the inner peripheral side of the cathode fitting 12 is Can be pressed from the cathode metal fitting 1
Since the 2 and the cylindrical jig 17 have complementary taper shapes, there is no problem in assembling and dismounting. The taper inclination should be appropriately selected depending on the size of the cathode fitting 12, etc., but is preferably about 2 to 5 °.

In the joining method of the present invention, thermocompression bonding may be performed in the same manner as before except that the pressing means from the inner peripheral surface side of the cathode fitting is used as described above. That is, as shown in FIG. 1, a lower jig 20, an insulating ring 10, a bonding material 11, a collar portion formed on the outer peripheral surface of a hollow tubular cathode metal fitting 12, and an upper jig 19 are sequentially laminated to form an inside of the cathode metal fitting. With the cylindrical jig 17 loosely inserted on the circumferential side, vertical pressure may be applied from one or both of the jigs 19 and 20 under a high temperature condition of about 540 to 560 ° C.

The joining material 11 is extended by plastic flow between the upper end surface of the insulating ring 10 and the lower surface of the flange 12 a of the cathode fitting 12, and the gap between the inner peripheral surface of the insulating ring 10 and the outer peripheral surface of the cathode fitting 12 is increased. It also flows into the part 22. In this state, pressure is applied from the vertical direction of the collar portion 12a and the inner peripheral surface side of the cathode fitting 12 so that the lower surface of the collar portion 12a and the insulating ring 1
0 not only on the upper end surface but also on the lower side of the collar 12a
The joint material 11 continuously joins up to the gap 22 between the outer peripheral surface and the inner peripheral surface of the insulating ring 10, and the joint portion also becomes longer.

By doing so, the strength of the joint portion between the insulating ring 10 and the cathode fitting 12 is increased, and the gap 2
Since the invasion of sodium from 2 is prevented, the life of the entire battery can be extended.

In the present invention, the insulating ring 1 is also used.
0, bonding material 11, cathode fitting 12, upper jig 19, lower jig 2
As for 0, the same one as before can be used.
The insulating ring 10 is preferably made of an insulating hollow cylindrical ceramic because it is necessary to maintain the electrical insulation between the anode metal fitting and the cathode metal fitting, and α-alumina or the like is preferable in view of strength and cost. used.

The cathode fitting 12 may be any member having a collar portion on the outer peripheral surface of the hollow tube, and generally has a thickness of 1 to 1.
It is composed of a thin plate of aluminum or the like having a thickness of about 2 mm. It is preferable to use an aluminum brazing material as the bonding material 11, and as the material of the upper jig 19 and the lower jig 20, SUS430, SUS403, Invar alloy, silicon nitride, alumina, or the like having a small coefficient of thermal expansion is used. It is preferable to use ceramics. Silicon nitride, alumina, etc. are SUS43
0, the coefficient of thermal expansion is smaller than that of SUS403, and the coefficient of thermal conductivity is higher than that of other ceramics, which is particularly preferable.

When performing thermocompression bonding, as shown in FIG. 4, a hollow cylindrical backup ring 13 made of ceramic such as α-alumina is fitted to the outer peripheral surface of the upper side of the flange 12a of the cathode fitting 12. It is preferable to dispose them collectively. This is because it is possible to prevent the jig 19 and the flange portion 12a of the cathode fitting 12 from being adhered to each other at the time of hot-press bonding, and to prevent the cathode fitting 12 from expanding and contracting during high-temperature operation after forming the battery.

Further, when the anode metal fitting for bonding the insulation ring 10 to the anode container is thermocompression bonded to the lower end surface of the insulation ring 10, the anode metal fitting 15 and the cathode metal fitting 12 are connected as shown in FIG. It is also preferable to perform thermocompression bonding at the same time. This is because the manufacturing process can be simplified if the anode fitting 15 and the cathode fitting 12 are hot-press bonded at the same time.

[0029]

EXAMPLE An example of a connecting structure of an insulating ring and a cathode fitting constructed by using the joining method of the present invention will be described below in more detail with reference to the drawings, but the present invention is not limited to the following example. is not.

[0030]

[0031]

[0032]

[0033]

Example 1 First, as shown in FIG. 2, the lower jig 40 and the inner peripheral surface on the lower end side are not shown in the state where the cylindrical jig 37 is loosely inserted on the inner peripheral side of the cathode fitting 32. An insulating ring 30 to which a solid electrolyte tube is joined by glass, a joining material 31, a collar portion 12a formed on the outer peripheral surface of the hollow tube portion 12b of the cathode fitting 12, and an upper jig 39.
Were sequentially laminated to form a work.

Next, under vacuum conditions at 540 to 560 ° C., 6 tons are applied to the work from the lower jig 40 side in the upward direction.
A load of n was applied. That is, the upper jig 39 pressed the upper end surface of the cathode fitting flange 32a and the upper end surface of the cylindrical jig 37, and the lower jig 40 pressed the lower end portion of the insulating ring 30.

In the first embodiment, the clearance between the inner peripheral surface of the cathode metal fitting 32 and the outer peripheral surface of the cylindrical jig 37 at the time of forming the work (normal temperature) is 100 μm, and the outer peripheral surface of the cylindrical jig 37 and the inner peripheral surface of the cathode metal fitting 32. Thermocompression bonding was performed without tapering the surface. The material of the cylindrical jig 37 was made of SUS304 having a linear thermal expansion coefficient of about 17 × 10 ⁻⁶ (1 / K). The joining material 31 was an aluminum brazing material.

In Example 1, the cathode fitting flange 32 a and the insulating ring 30 were firmly joined by the joining material 31.

(Comparative Example 1) As shown in FIG. 2, in a state where the cylindrical jig 37 was loosely inserted on the inner peripheral side of the cathode fitting 32,
A lower jig 40, an insulating ring 30 in which a solid electrolyte tube (not shown) is glass-bonded to the inner peripheral surface on the lower end side, a bonding material 31,
Collar part 32 formed on the outer peripheral surface of the hollow tubular cathode metal fitting 32.
A and the upper jig 39 were sequentially laminated to form a work.

Next, under vacuum conditions at 540 to 560 ° C., 6 tons are applied to the work from the lower jig 40 side in the upward direction.
A load of n was applied. That is, the upper jig 39 pressed the upper ends of the flange 32 a and the cylindrical jig 37, and the lower jig 40 pressed the lower end of the insulating ring 30.

The cylindrical jig 37 has a linear thermal expansion coefficient of about 17
Made of SUS304 of × 10 ^-6 (1 / K), the inner peripheral surface of the cathode fitting 32 and the cylindrical jig 3 during work formation (normal temperature)
7 The clearance from the outer peripheral surface was 300 μm. An aluminum brazing material was used as the bonding material 31. In Comparative Example 1, the collar 32 a of the cathode fitting 32 and the insulating ring 30
And were firmly joined by the joining material 31.

[0041] (Evaluation method) Example 1 some have the insulating ring are joined by the method of Comparative Example 1 and the cathode fitting, Na by the following method
The corrosion resistance was evaluated.

A sodium-sulfur battery was constructed by loading the joined insulating ring and cathode fitting into an anode container (not shown), and the battery was not charged or discharged to obtain 360
The operation of heating to 360 ° C., keeping at 360 ° C. for 1 hour, lowering to 280 ° C., keeping at 280 ° C. for 1 hour is one cycle, and the operation is continuously performed for 3000 cycles,
The extent of Na erosion was compared.

The degree of erosion due to Na is the distance at which Na invades from the outer peripheral surface of the hollow tube portion in the radial direction of the cathode fitting flange at the contact surface between the insulating ring and the cathode fitting flange (hereinafter,
It is called "erosion distance". ) Was used as the standard.

As a result, in the battery incorporating the coupling structure of Comparative Example 1, the erosion distance was about 1 to 2 mm. On the other hand, in the battery incorporating the coupling structure of Example 1 ,
The erosion distance was 0 mm, and no erosion was observed on the contact surface between the insulating ring and the flange of the cathode fitting. That is,
By the hot pressing method of Example 1, a bonded structure having high corrosion resistance to Na could be formed.

[0045]

As described above, according to the present invention, it is possible to obtain a joint structure of an insulating ring and a cathode metal fitting, which has high joint strength and high corrosion resistance to sodium. Therefore, sodium-having a long life and excellent economic efficiency
A sulfur battery can be provided.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional explanatory view showing a coupling structure of an insulating ring and a cathode fitting of the present invention.

FIG. 2 is a partial cross-sectional explanatory view showing a conventional coupling structure of an insulating ring and a cathode fitting.

FIG. 3 is a partial cross-sectional explanatory view showing a conventional method for joining an insulating ring and a cathode fitting.

FIG. 4 is a partial cross-sectional explanatory view showing an example of the joining method of the present invention.

[Explanation of symbols]

10 ... Insulating ring, 11 ... Bonding material, 12 ... Cathode metal fitting (1
2a ... collar part, 12b ... hollow tube part), 13 ... backup ring, 14 ... bonding material, 15 ... anode metal fitting, 16 ... bonding material, 17 ... cylindrical jig, 19 ... upper jig, 20 ... lower cure Ingredient,
21 ... Solid electrolyte tube, 22 ... Gap part, 30 ... Insulating ring, 31 ... Bonding material, 32 ... Cathode metal fitting (32a ... Collar part, 3
2b ... hollow tube portion), 37 ... cylindrical jig, 39 ... upper jig,
40 ... Lower jig, 41 ... Insulating ring inner peripheral surface, 42 ... Gap part.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01M 10/39

Claims (3)

(57) [Claims] 1. A cylindrical insulating ring having a hollow portion,
Flange portion is formed on an outer peripheral surface, and a cathode fitting hollow tubular capable of fitting into the hollow portion, Na thermally pressure bonded via the bonding material
A method of joining an insulating ring of a thorium-sulfur battery and a cathode metal fitting , comprising: pressing the upper and lower directions of the collar portion and the inner peripheral surface of the cathode metal fitting to form the lower surface of the collar portion, the upper end surface of the insulating ring, and the collar. In continuously joining the outer peripheral surface of the cathode metal fitting on the subordinate side and the inner peripheral surface of the insulating ring, pressing from the inner peripheral surface side of the cathode metal fitting is performed by a cylindrical jig that can be fitted to the inner circumference of the cathode metal fitting. sodium with clearance of the inner peripheral surface and the outer circumferential surface of the cylindrical jig of the cathode metal is characterized in that as is 30~170μm performed - absolute sulfur battery
How to join the edge ring and cathode fitting . Wherein sodium of claim 1 outer peripheral surface of the inner peripheral surface of the cathode metal and the cylindrical jig is complementary tapered
Mu-Sulfur battery insulation ring and cathode fittings joining method. 3. A combined structure of an insulating ring of a sodium-sulfur battery and a cathode fitting formed by the joining method according to claim 1.