JP2003157890A - Sodium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sodium secondary battery suitably used for an electric power storage device and an electric automobile. SOLUTION: This sodium secondary battery is constituted by frictionally agitating and joining a plurality of aluminum metallic plates or aluminum alloy metallic plates to form a negative electrode vessel and/or a positive electrode vessel, and is characterized in that the plate thickness of the mutually joined metallic plates is different from each other, and a rotary tool used for frictional agitating-joining is drawn out of the inside of the metallic plate thicker in the plate thickness positional far from the frictional agitating-joining part. Thus, the negative electrode vessel and the positive electrode vessel of the sodium secondary battery can be airtightly easily joined and sealed, and reliability of the joining part and a sealing part and a manufacturing yield can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a sodium secondary battery suitable for use in a power storage device, an electric vehicle and the like.

[0002]

2. Description of the Related Art Liquid sodium in a negative electrode container, elements of sulfur, selenium and tellurium as positive electrode active materials in a positive electrode container and chlorides thereof, sodium polysulfide and metal chlorides (metals are Al, Ni, Fe, etc.) A sodium secondary battery with a structure in which the negative electrode chamber and the positive electrode chamber are separated by a β-type or β ″ -type solid electrolyte made of beta-alumina ceramics has attracted attention because of its long life and large energy density. It is expected to be applied to electric vehicles including storage devices and hybrid vehicles, etc. In order to put this battery to practical use, it is essential to ensure the reliability of the battery and to reduce the cost. It is desirable to reduce the internal resistance to improve the battery efficiency so as to operate at high output, or to increase the size of the single cell to reduce the number of batteries per kW or kWh.

In a conventional battery, as a countermeasure for that, as shown in, for example, Japanese Patent Application Laid-Open No. 7-302612, a negative electrode container and a positive electrode container that share electrodes are made of aluminum alloy to reduce battery resistance and improve battery efficiency. Methods to improve have been adopted. Further, generally, the negative electrode container and the positive electrode container are configured by a method of joining a plurality of metal plates, and the joining method is laser welding, arc welding, or electron beam welding described in JP-A-7-176329. Is used.

However, since the welding temperature is high in laser welding and arc welding, voids may be generated in the welded portion,
Problems such as the metal plate being deformed due to the temperature being raised to the periphery of the weld and the welding process becoming complicated because electron beam welding requires welding in a vacuum are common. It has a drawback that it is difficult to manufacture and cost reduction cannot be achieved. In particular, when aluminum or an aluminum alloy is used as a metal plate forming the negative electrode container or the positive electrode container, there is a problem that the metal plate is easily deformed during welding or a void is generated, and the battery production yield is not improved.

As a method of joining aluminum and aluminum alloys, for example, JP-A-11-090655, JP-A-2000-061660, and JP-A-2000-06.
As can be seen in Japanese Patent No. 1662, the joining by the friction stir welding method is excellent, and by doing so, it is possible to suppress the temperature rise around the joined portion and prevent the occurrence of voids and deformation. However, in the friction stir welding method, since the rotary tool is pushed into the metal for welding, the tool needs to be pulled out from the metal after the welding is completed. For this reason,
In the process of joining the negative electrode container and positive electrode container of sodium secondary batteries and the process of sealing the through holes, it takes time to remove the holes that remain after the tool is pulled out, especially by rotating the rotating tool in the radial direction of the container to perform airtight bonding. If it is, it is extremely difficult to remove the hole, while if the hole is left, there is a problem that it tends to hinder the airtight sealing and strength retention of the container,
Measures against these problems are indispensable for practical use.

[0006]

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to easily perform airtight bonding or hermetic sealing of a negative electrode container or a positive electrode container, and to provide a joint or sealing. To provide a sodium secondary battery with high reliability and high manufacturing yield.

[0007]

The first sodium secondary battery of the present invention is constructed by friction stir welding a plurality of aluminum metal plates or aluminum alloy metal plates for the negative electrode container and / or the positive electrode container. The thickness of the joined metal plates is different from each other, and the rotating tool used for the friction stir welding is selected from the metal plate having the thicker thickness at a position distant from the friction stir welding part. Characterized by being pulled out.

[0008] By doing so, it is not necessary to remove the hole left after the tool is pulled out, the airtight bonding of the negative electrode container and the positive electrode container can be easily performed, and the reliability of the bonding portion and the manufacturing yield can be improved. A high sodium secondary battery is realized.

Here, the plate thickness of one of the friction stir welded metal plates is at least twice the plate thickness of the other metal plate, and the metal plate forming the negative electrode lid which is a part of the negative electrode container. Is greater than the thickness of the metal plate that constitutes the negative electrode body or negative electrode flange that is a part of the negative electrode container, or
And, it is particularly preferable that the plate thickness of the metal plate forming the positive electrode lid which is a part of the positive electrode container is larger than the plate thickness of the metal plate forming the positive electrode body and the positive electrode flange which are a part of the positive electrode container. .

The second sodium secondary battery of the present invention is for vacuuming or controlling gas pressure provided on a metal plate constituting a negative electrode lid, a negative electrode body or a negative electrode flange which is a part of the negative electrode container. Of the positive electrode cover, which is a part of the positive electrode container, the positive electrode body, or the metal plate that constitutes the positive electrode flange, which is a part of the positive electrode container, for vacuuming or for controlling gas pressure by friction stir welding. The rotary tool used for the friction stir welding is pulled out from the inside of the metal plate that is sealed and has a plate thickness larger than the inner diameter of the through hole and is located away from the through hole. Is characterized by.

By doing so, it is possible to realize a sodium secondary battery in which the through hole can be easily hermetically sealed and the sealing portion has high reliability and a high production yield.

Further, in the first and second sodium secondary batteries, a current collector made of aluminum or aluminum alloy is provided along the solid electrolyte in the positive electrode container, and the current collector is It is joined to the positive electrode lid and / or the positive electrode body forming the positive electrode container, the solid electrolyte is a solid electrolyte bag tube, and the solid electrolyte bag tube is laid in a horizontal or diagonal direction. Is desirable.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a sodium secondary battery according to the first embodiment of the present invention. In the figure, a solid electrolyte bag tube made of β-type or β ″ -type beta-alumina ceramics is usually used as the sodium ion conductive solid electrolyte 1. Note that a flat solid electrolyte is used instead of the solid electrolyte bag tube. Can also be used.
The negative electrode container 2 and the positive electrode container 3 constitute the negative electrode chamber 4 and the positive electrode chamber 5 together with the solid electrolyte 1, and the material thereof is Al or Al alloy, or Cr or Mo on the surface thereof,
A material provided with a corrosion-resistant layer mainly composed of Ti, C, Si or the like, or a clad material of Al alloy and SUS or the like is usually used.

The insulating member 6 insulates and separates the negative electrode container 2 and the positive electrode container 3 from each other, and is joined to them, and is usually made of α-alumina ceramics and is provided in the vicinity of the opening of the solid electrolyte 1 although not shown. It is glass-bonded or is integrally sintered with the opening of the solid electrolyte 1 using ceramics such as α-alumina and magnesium aluminum spinel. For joining the negative electrode container 2 and the positive electrode container 3 to the insulating member 6, although not shown, using Al or Al alloy as a joining material, the liquidus temperature of the joining material or less or the solidus temperature or less A heat-pressure welding method in which the material is heated and pressure-bonded is generally performed.

Further, liquid sodium 7 is placed in the negative electrode chamber 4.
A metallic sodium container 8 such as an iron alloy such as SUS or an Al alloy is provided to store sodium, and sodium 7 is gravity or an inert gas 9 such as nitrogen gas or Ar gas filled in the sodium container 8 during discharge. Of the through hole 10 provided in the sodium container 8 while being charged by the pressure of sodium which penetrates through the solid electrolyte 1 during charging.
Go in and out. By providing the sodium container 8 in this way, a gap 1 between the solid electrolyte 1 and the sodium container 8 is formed.
The amount of sodium present in 1 can be reduced, and the safety of the battery when the solid electrolyte 1 is damaged is improved.

In this figure, since the structure during battery assembly is shown, sodium does not exist in the gap 11, but sodium 7 in the sodium container 8 passes through the through hole 10 during battery operation. Is supplied to the gap 11. Further, although the sodium container 8 is separated from the negative electrode container 2, a structure in which the sodium container 8 and the negative electrode container 2 are integrated is also possible.

Further, between the side surface of the solid electrolyte 1 in the positive electrode chamber 5 and the positive electrode body portion 31 which is a part of the positive electrode container 3, or between the body portion of the current collector 15 as shown in FIG. The porous conductive material 12 and the porous material 13 are installed. Here, in the case of a sodium-sulfur battery, the positive electrode active material 14 made of sulfur or / and sodium polysulfide is filled in the positive electrode chamber 5, and the positive electrode active material 14 is the porous conductive material 12 or the porous material 13. It is impregnated in and promotes the battery reaction. On the other hand, in sodium secondary batteries other than sodium-sulfur batteries, the positive electrode active material 14 includes elements of sulfur, selenium, tellurium, chlorides thereof, and metal chlorides (metals are Al, Ni,
Fe or the like) is used.

An aggregate of carbon fibers and carbon powder is used as the porous conductive material 12, and in particular, the thickness in the radial direction along the solid electrolyte 1 is about 3 to 20 mm, 1200 to 2000.
It is desirable to use a PAN (polyacrylonitrile) -based or pitch-based carbon fiber mat heated at ° C. Further, a ring-shaped or strip-shaped carbon fiber mat in which carbon fibers are arranged in the plane direction is used, and the carbon fiber mat is installed such that the plane direction of the mat is perpendicular to the side surface of the solid electrolyte 1. It is possible to reduce the resistance of the carbon fiber mat along the radial direction and improve the battery efficiency.
On the other hand, as the porous material 13, an aggregate of fibers or particles of ceramics such as alumina or glass is usually used, and the radial thickness along the solid electrolyte 1 can be set to about 0.1 to 0.5 mm. desirable.

Further, in the sodium secondary battery having the structure shown in FIG. 1, the negative electrode body portion 21 and the negative electrode lid 22 which are a part of the negative electrode container 2, and the positive electrode body portion 31 which is a part of the positive electrode container 3.
And the positive electrode lid 32 are friction stir welding parts 61 and 63, respectively.
And the through holes 41 and 51 provided in the negative electrode lid 22 and the positive electrode lid 32 are hermetically sealed by the friction stir welding portions 62 and 64, respectively.

Here, in the case of friction stir welding of metal plates, since the metal plates are joined by pushing the rotary tool into the metal plates and friction stirring, the temperature rise of the metal plates around the joint is suppressed. While the deformation and voids of the metal plate are prevented, there is a problem that holes remain when the rotary tool is pulled out after joining.

To deal with this problem, in the structure of the present invention, as shown in FIG. 1, the thickness of the metal plate forming the negative electrode lid 22 is smaller than that of the metal plate forming the negative electrode body portion 21. In addition to increasing the thickness, the thickness of the metal plate forming the positive electrode lid 32 is made larger than the thickness of the metal plate forming the positive electrode body portion 31. By doing so, the pressing depth of the rotary tool is made approximately the same as the thickness of the metal plate forming the negative electrode body portion 21 and the positive electrode body portion 31, and the negative electrode body portion 21 and the negative electrode lid 2 are
2, and after the positive electrode body 31 and the positive electrode lid 32 are circumferentially airtightly joined by friction stir welding, the rotary tool is moved away from the joining portion and moved into the negative electrode lid 22 or the positive electrode lid 32 having a thick metal plate. Then, the rotary tool is pulled out.

That is, although not shown, the rotary tool is moved to the upper side of FIG. 1 in the case of the negative electrode and to the lower side in the case of the positive electrode after joining to join the negative electrode body portion 21 and the positive electrode body portion 31. By pulling out the rotary tool at a position distant from the portion, holes are provided in the negative electrode lid 22 and the positive electrode lid 32 that are made of a metal plate having a larger wall thickness than the depth of the holes.
The airtightness of the joint is secured. Further, by increasing the plate thickness of the metal plate forming the negative electrode lid 22 and the positive electrode lid 32, it is possible to ensure sufficient mechanical strength even if holes are provided.

As described above, the thickness of one metal plate to be friction stir welded as in the present invention is made larger than the thickness of the other metal plate, and the pushing depth of the rotary tool is the thickness of the thinner metal plate. This is the same as when connecting the negative electrode container and positive electrode container of the sodium secondary battery by pulling out the rotary tool from a position away from the joint in the thicker metal plate. Even when the rotary tool is moved in the radial direction of the container to perform airtight bonding, it is not necessary to remove the hole remaining after the rotary tool is pulled out. Also, prevent the remaining holes from interfering with the airtight sealing and strength retention of the container,
It is possible to realize a sodium secondary battery in which the positive electrode container can be easily airtightly bonded, and the reliability of the bonding portion and the manufacturing yield are high.

Further, in FIG. 1, the through holes 41 and 51 provided in the negative electrode lid 22 and the positive electrode lid 32 are hermetically sealed by friction stir welding portions 62 and 64, respectively. In the sodium secondary battery, in order to prevent the oxidation of sodium 7, the inside of the negative electrode chamber 4 is evacuated or filled with an inert gas such as nitrogen or argon at a predetermined pressure and sealed. Generally, in the structure of the present invention, when the through hole 41 is sealed, the temperature hardly rises except at the sealing place. Therefore, the sodium 7 melts and moves in the negative electrode chamber 4 at the time of sealing. There is no problem that occurs, and there is an advantage that reliability of airtight sealing and mass productivity are high.

The same problem occurs when the positive electrode lid 32 is hermetically sealed. When a sodium-sulfur battery is used as the sodium secondary battery, the positive electrode active material 14 is filled with sulfur. However, when the inside of the positive electrode chamber 5 is evacuated or filled with an inert gas such as nitrogen or argon having a predetermined pressure for sealing, the structure of the present invention has a problem of temperature increase except in the vicinity of the through hole 51. There is no advantage that sulfur does not evaporate and the problem of obstructing the sealing does not occur.

When the through holes 41 and 51 are hermetically sealed, since the pushing depth of the rotary tool may be about the inner diameter of the through holes, the negative electrode lid at a position different from the through holes 41 and 51 in the radial direction. 22 and the metal plates 220 and 3 forming the positive electrode lid 32
The plate thickness of 20 is made larger than the inner diameter of the through hole, and after the through hole is sealed, the rotary tool is moved to a position away from the through hole and rotated from the metal plate 220 of the negative electrode lid or the metal plate 320 of the positive electrode lid. Just pull out the tool. By doing so, it is not necessary to remove the remaining hole, and even if the hole is left, there is no problem in hermetic sealing and mechanical strength, and the reliability of the sealed portion of the sodium secondary battery is improved and It is possible to improve the manufacturing yield.

FIG. 2 is a cross-sectional view showing a structural example of the sodium secondary battery of the second embodiment of the present invention, in which the same reference numerals as those in FIG. 1 indicate the same parts. In FIG. 2, the bag-shaped solid electrolyte 1 is laid horizontally or obliquely so that the through hole 10 provided in the sodium container 8 is on the lower side, and the negative electrode chamber is provided inside the solid electrolyte 1. 4, the positive electrode chamber 5 is provided on the outer side, the current collector 15 is provided along the outer side surface of the solid electrolyte 1, and the porous conductive material 12 and the porous conductive material 12 are provided between the side surface of the solid electrolyte 1 and the current collector 15. A porous material 13 is installed. Although not shown, when a flat solid electrolyte is used, a current collector is provided along the flat plate.

As described above, since the bag-shaped solid electrolyte 1 is laid horizontally or obliquely, the bag-shaped solid electrolyte 1 having a length larger than the diameter is used as usual. When used, the height of the battery in the vertical direction becomes smaller than when the solid electrolyte 1 having a tubular shape is erected, and the concentration distribution and composition distribution of the positive electrode active material 14 due to gravity in the vertical direction in the positive electrode chamber 5 are less likely to be attached. As a result, electromotive force distribution and circulating current based on it are less likely to occur in the battery, and as a result, the efficiency of the battery is improved.

Further, by collecting current using the current collector 15 provided along the solid electrolyte 1 in the positive electrode chamber 5, the porous conductive material existing in the space between the side surface of the solid electrolyte 1 and the current collector 15 is collected. The material efficiency can be improved by making the thickness of the material 12 relatively small and reducing the resistance thereof. Also, the current collector 1
The capacity of the battery can be increased by increasing the space between the cathode 5 and the positive electrode container 3 to increase the volume in the positive electrode chamber. That is, as a result of these, it is possible to increase the capacity of the battery without increasing the number of components while keeping the battery resistance low.
It is possible to obtain a highly practical large-capacity battery that can easily realize cost reduction.

Further, by making the length of the bag-shaped solid electrolyte 1 larger than the diameter, the ratio of the internal volume of the solid electrolyte 1 to the surface area can be made relatively small. As a result, the current density per surface area of the solid electrolyte 1 during operation within a predetermined time should be smaller than that in the case of using the bag-shaped solid electrolyte 1 having a diameter similar to the length or a larger diameter. As a result, there is an advantage that the discharge voltage drop and the charge voltage increase given by current × internal resistance are reduced, and the battery efficiency can be increased. Note that this effect is particularly remarkable when the length of the bag-shaped solid electrolyte 1 is increased in order to increase the size of the unit cell, and the structure of the present invention increases the size of the battery, that is, increases the capacity and improves efficiency. Compatibility is possible.

Further, in this structure, the current collector 15
Since the battery characteristics can be controlled by the above, the shape of the positive electrode container can be various structures such as a cylindrical shape, an elliptic cylinder shape and a rectangular parallelepiped shape according to the purpose.

That is, when the positive electrode container 3 has a cylindrical shape, there is an advantage that the positive electrode container 3 has high mechanical strength against thermal stress when the temperature is raised or lowered and external atmospheric pressure during operation, and the reliability of the battery is high. . In particular, when the positive electrode container 3 is made of aluminum or an aluminum alloy, there is a problem that the positive electrode container 3 is likely to undergo creep deformation due to stress at high temperature. However, by making the positive electrode container 3 into a cylindrical shape, it is added to the positive electrode container 3. The stress is reduced and the deformation is easily prevented. Although not shown, it is also possible to make the cross section of the positive electrode container 3 into an elliptical shape. By doing so, the mechanical reliability is improved as compared with the case where the positive electrode container 3 has a rectangular parallelepiped shape.

On the other hand, by making the positive electrode container 3 into a rectangular parallelepiped shape, the energy density of the module containing a plurality of batteries is improved. That is, in the case where the upper and lower surfaces of the positive electrode container 3 are formed into a parallel plane shape, the battery installed horizontally is hard to move, the stability of the posture is improved, and a plurality of the batteries are placed in the heat insulating container constituting the module. When accommodating the sodium secondary battery of, the space between the batteries stacked vertically and the space between the heat retaining container and the battery in the vertical direction can be reduced, the packing density of the battery is improved, and the energy density of the module is increased. There are advantages. Further, by making the side surface of the positive electrode container 3 into a parallel plane shape, the lateral distance between the batteries housed in the heat retaining container and the lateral distance between the heat retaining container and the battery can be reduced, and the energy density of the module can be reduced. improves. In addition,
In order to particularly improve the energy density of the module, it is desirable that the side surface of the positive electrode container 3 be rectangular parallelepiped, and by doing so, the interval between the cells in the vertical direction and the lateral direction and the interval with the heat retaining container can be reduced.

Furthermore, when the bag-shaped solid electrolyte 1 is installed obliquely, the vertical height of the battery can be reduced by setting the angle between the axial direction and the horizontal direction of the solid electrolyte 1 to ± 45 ° or less. desirable. Considering the suction height of the positive electrode active material 14 due to the surface tension of the porous conductive material 12 or the porous material 13, the vertical direction of the porous conductive material 12 or the porous material 13 in the case of the sodium-sulfur battery is considered. It is desirable to tilt the solid electrolyte 1 at an angle of 15 cm or less so as to secure the suction height of sulfur and sodium polysulfide.

Here, in order to reduce the height of the battery in the vertical direction for the purpose of improving the battery efficiency, it is particularly desirable to horizontally install the bag-shaped solid electrolyte 1. This effect is particularly remarkable when the length of the bag-shaped solid electrolyte 1 is increased in order to increase the capacity of the unit cell, and the structure of the present invention makes it possible to increase the capacity of the battery and improve the efficiency at the same time. It is possible.

In addition to making the volume of the positive electrode active material 14 larger than the void volume of the porous conductive material 12 or the porous material 13 so that the porous conductive material 12 or the porous material 13 is impregnated, By forming a liquid phase of the positive electrode active material 14 on the outer side of the current collector 15 in 5 and providing a penetrating portion 16 in the current collector 15 to move the positive electrode active material 14 into and out of the porous conductive material 12,
The battery capacity can be expanded.

The current collector 15 has a thickness of 0.3 to 5 m.
Al, Al alloy of about m 2 and a clad material of these and SUS or the like are used, and Co-based alloy, Cr / Fe alloy, Al / Si alloy, SUS, Cr, etc. are used on the contact surface with the porous conductive material 12.
A corrosion resistant conductive layer made of C, Mo, Cr, Mo carbide or nitride is provided by a method such as thermal spraying or plating, or those in which these corrosion resistant particles or fibers are bonded or embedded in the surface of Al or Al alloy are used. . Further, as the penetrating portion 16, a circular or rectangular parallelepiped hole having a diameter, a width and a length of about 1 to 10 mm,
Or, a slit having a width of 1 to 10 mm is provided between them, and the area ratio is 5 to 50 of the area of the current collector 15.
% Is preferable.

In FIG. 2, as in FIG. 1, the negative electrode container 2
The metal plates forming the positive electrode container 3 are airtightly joined together by the friction stir welding method. That is, the negative electrode flange 23 that is a part of the negative electrode container 2 and the negative electrode lid 22 that also serves as a negative electrode body part are the friction stir welding parts 65, and the positive electrode flange 33, the positive electrode body part 31, and the positive electrode body part that are a part of the positive electrode container 3. Body 31 and positive electrode lid 32
And friction stir welding parts 66 and 63, respectively.

As described above, the metal plates to be joined have different plate thicknesses. Specifically, the thickness of the metal plates is defined as negative electrode cover 22> negative electrode flange 23, positive electrode cover 32>.
The positive electrode body 31> the positive electrode flange 33. In this way, when performing friction stir welding, the indentation depth of the rotary tool is made approximately the same as the thickness of the metal plate with a small plate thickness, and the rotary tool is moved away from the welded part after the welding, and the metal plate with a large plate thickness is joined. By pulling out from the inside of the plate, the hole remains in the metal plate having a larger thickness than the depth of the hole, so that it is possible to ensure the airtightness of the joint portion and the mechanical strength.

The structure of the friction stir welding portion 63 shown in FIG. 2 is almost the same as that of the friction stir welding portion 63 shown in FIG. On the other hand, in the case of the friction stir welding parts 65 and 66, as the thickness of the metal plate, the plate thickness of the negative electrode lid 22 is twice or more the plate thickness of the negative electrode flange 23, and the plate thickness of the positive electrode body part 31 is the positive electrode flange 33. It is desirable that the thickness is at least twice the plate thickness. By doing so, when the pushing depth of the rotary tool is made approximately the same as the thickness of the metal plate having a small thickness, the negative electrode lid 22 or the positive electrode body portion 31 at the position of the hole generated by the pulling out of the rotary tool. Has a thickness equal to or greater than the thickness of the negative electrode flange 23 or the thickness of the positive electrode flange 33, respectively, sufficient mechanical strength is ensured, and holes are generated by the rotary tool for friction stir welding. However, there is an advantage that reliability of the airtightness and mechanical strength of the battery can be secured.

Further, the through holes 41 and 51 provided in the negative electrode lid 22 and the positive electrode lid 32 are respectively friction stir welding parts 62,
Although it is hermetically sealed with 64, in this case also, the negative electrode lid 2
Although the plate thickness of the metal plate constituting 2 or the positive electrode lid 32 is made larger than the inner diameter of the through hole, the rotary tool is moved to the upper side or the lower side in FIG. By pulling out, holes are left in the negative electrode lid 22 and the positive electrode lid 32 having a larger wall thickness than the depth of the holes, and battery reliability such as airtightness and mechanical strength is secured. Further, by increasing the plate thickness of the metal plate forming the negative electrode lid 22 and the positive electrode lid 32, the pressure applied to the positive electrode body portion 31 and the negative electrode flange 23 when the battery is laid horizontally or diagonally is reduced. ,
There is also an advantage that the reliability of the battery is improved.

Further, though not shown, the through hole 41
To the negative electrode body portion 21 or the negative electrode flange 23 shown in FIG.
The through hole 51 is provided in the positive electrode body portion 31 or the positive electrode flange 33 so that the thickness of the negative electrode body portion 21 or the negative electrode flange 23 or the metal plate forming the positive electrode body portion 31 or the positive electrode flange 33 is smaller than the inner diameter of the through hole. It is also possible to increase the size and seal the through hole by friction stir welding, and then pull out the rotary tool at a position away from the through hole.

Further, the current collector 15 is joined to the inside of the positive electrode lid 32 by the friction stir welding part 67, but it is also possible to join to the inside of the positive electrode body part 31 and the positive electrode flange 33 although not shown. Is. Further, since this joining is intended for electric conduction and airtight joining is not necessary, if the thickness of the metal plate forming the positive electrode lid 32, the positive electrode body 31 and the positive electrode flange 33 is sufficiently large, the rotary tool can be pulled out after the joining. Therefore, even if a hole is left in a part of the current collector 15, no problem in battery characteristics or reliability occurs. As described above, since there is no need for airtight joining in this case, it is also possible to use TIG welding or laser welding.

As a concrete example, as shown in FIG. 2, a cylindrical bag having an outer diameter of about 60 mm, a length of about 600 mm, and a wall thickness of about 1.5 mm, which is made of a lithium-doped β ″ alumina sintered body as the solid electrolyte 1. Further, the negative electrode container 2 and the positive electrode container 3 are made of Al alloy, and the sodium container 8 is made of SUS.
For the current collector 15, an inner surface of the body of an Al alloy provided with the penetrating portion 16 was chromium-plated, or an iron / chromium alloy, Stellite-6 or Stellite-6B was sprayed. On the other hand, an α-alumina sintered body ring is used as the insulating member 6, and after glass bonding to the opening of the solid electrolyte 1, the ends of the negative electrode flange 23 and the positive electrode flange 33 are arranged on the surface of the sintered body ring, and Al The insulating member 6 was thermocompression-bonded using a -Si alloy foil.

Next, sodium 7 and Ar gas 9 of about 0.01 MPa are filled in the sodium container 8 through the through hole 10 to fill the through hole 10 with Sn91Zn, though not shown.
After sealing with tin-based solder such as Sn96.5Ag or Sn95Sb, the sodium container 8 is installed in the solid electrolyte bag tube 1, and the negative electrode flange 23, the negative electrode lid 22 also serving as the negative electrode body, and the positive electrode flange 33 are provided. The positive electrode body 31 was friction stir welded. Here, the negative electrode flange 23 and the positive electrode flange 3
The plate thickness of the Al alloy forming 3 is 2 mm, the plate thickness of the Al alloy forming the positive electrode body 31 is 4 mm, the negative electrode lid 22 and the positive electrode lid 3
The plate thickness of the Al alloy constituting 2 is 6 mm.

In the friction stir welding, it is necessary to push the rotating tool into the joint while rotating it, and in order to support the load for this purpose, although not shown, the inside of the positive electrode body 31 is made of iron. An alloy cylinder was installed. On the other hand, since the plate thickness of the negative electrode cover 22 is sufficiently large, this load can be supported by horizontally placing the battery and fixing the lower part.

In this way, the battery is laid horizontally and the rotary tool is pushed in from the upper part to rotate the battery to join it in the radial direction, and after turning once, the rotary tool is joined to the negative electrode flange 23 and the positive electrode flange 33. The negative electrode flange 23 and the negative electrode lid 2 by pulling the rotary tool out of the negative electrode lid 22 and the positive electrode body 31 by moving the rotary tool to a position away from the negative electrode lid 22 and the positive electrode body 31.
2. The positive electrode flange 33 and the positive electrode body portion 31 were airtightly joined at the friction stir welding portions 65 and 66, respectively. The iron alloy cylinder installed inside the positive electrode body 31 was removed after joining.

Next, the inside of the negative electrode chamber 4 is evacuated to a negative electrode lid 2.
The second through hole 41 was hermetically sealed by the friction stir welding part 62.
At this time, after supporting the joint surface of the positive electrode flange 33 joined to the insulating member 6 and pressing the rotary tool from the outside of the negative electrode lid 22 to seal the through hole 41 having a diameter of 2 mm,
Move the rotary tool to a position away from the through hole 41,
The rotary tool was pulled out from the inside of the negative electrode lid 22.

On the other hand, the cylindrical current collector 15 having a metal plate thickness of 2 mm and the positive electrode lid 32 having a plate thickness of 6 mm are placed with the positive electrode lid 32 on the lower side and the cylindrical current collector 15 is erected vertically. In this state, the friction stir welding portion 67 was used for welding.

Further, a Teflon (registered trademark) rod is installed on the inner surface of the cylindrical current collector 15, and a porous conductive material made of a ring-shaped PAN-based carbon fiber mat having a radial thickness of about 9 mm is provided between them. The material 12 was compressed to a required thickness, laminated and filled, and at the same time, a porous material 13 made of an alumina fiber aggregate and having a thickness of about 0.3 mm was filled. Further, after the porous conductive material 12 was impregnated with sulfur to solidify the porous conductive material 12 and the porous material 13, the Teflon rod was pulled out.

Next, a cylindrical current collector 15 in which the positive electrode active material 14 is filled with a required amount of sulfur and the porous conductive material 12 and the porous material 13 are provided on the outer side surface of the solid electrolyte 1 is provided. Was installed, and the positive electrode body portion 31 and the positive electrode lid 32 were airtightly joined at the friction stir welding portion 63. Even in this case, the battery is laid sideways, the rotary tool is pushed in from the upper part, and the battery is rotated to bond the battery in the radial direction. Then, the rotary tool is located at a position away from the joint with the positive electrode body 31. And was pulled out from the inside of the positive electrode lid 32.

Finally, after the inside of the positive electrode chamber 5 is evacuated from the through hole 51, argon gas of about 0.03 MPa is filled in the positive electrode chamber, and the through hole 51 is hermetically sealed with the friction stir welding part 64, and sodium is A sulfur battery was created. Also in this case, as in the case of the friction stir welding portion 62, the end of the positive electrode body portion 31 joined to the positive electrode flange 33 is supported and the rotary tool is pressed from the outside of the positive electrode lid 32 to form the through hole 51. After sealing, the rotary tool was moved to a position away from the through hole 51, and the rotary tool was pulled out.

The sodium-sulfur battery thus obtained was placed horizontally so that the through hole 10 provided in the sodium container 8 was on the lower side, and the temperature was raised to 330.degree. During the course of this temperature rise, first, the sodium 7 melted, and the argon gas 9 accumulated in the upper portion of the sodium container 8 placed horizontally, and then the tin-based solder sealing the through hole 10 melted.
As a result, the sodium 7 is pushed by the gas pressure of the argon gas 9, moves through the through hole 10 to the gap 11 between the solid electrolyte 1 and the sodium container 8, and the sodium 7 comes into contact with the inner surface of the solid electrolyte 1. Then, battery operation became possible.

As a result of operating this sodium-sulfur battery horizontally at 330 ° C., the positive electrode active material 14 in the positive electrode chamber 5
Battery capacity is about 16
The internal resistance can be as large as 00 Ah and the internal resistance as small as about 1.3 mΩ, which makes it possible to achieve both large capacity and high efficiency. In addition, in this battery, by using the current collector 15,
Since the battery capacity can be increased by enlarging the positive electrode container 3 without enlarging the solid electrolyte bag tube 1,
Especially suitable for cost reduction.

[0056]

According to the present invention described above, airtight bonding and airtight sealing of the negative electrode container and the positive electrode container can be easily performed, and the reliability of the bonding portion and the sealing portion and the manufacturing yield are high. A sodium secondary battery is realized.

[Brief description of drawings]

FIG. 1 is a sectional view of a sodium secondary battery according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a sodium secondary battery according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Solid electrolyte, 2 ... Negative electrode container, 3 ... Positive electrode container, 4 ... Negative electrode chamber, 5 ... Positive electrode chamber, 6 ... Insulating member, 7 ... Sodium, 8
... Sodium container, 12 ... Porous conductive material, 13 ... Porous material, 14 ... Positive electrode active material, 15 ... Current collector, 21 ... Negative electrode body part, 22 ... Negative electrode lid, 23 ... Negative electrode flange, 31 ... Positive electrode body part , 32 ... Positive electrode lid, 33 ... Positive electrode flange 10, 41,
51 ... Through holes, 61, 62, 63, 64, 65, 66,
67 ... Friction stir joint.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01M 2/04 H01M 2/04 Z (72) Inventor Shigeru Sakaguchi 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki No. 1 in the Nuclear Power Division of Hitachi, Ltd. (72) Tetsuya Sado 3-1-1, Saiwaicho, Hitachi, Ibaraki Prefecture Sat. F-term in Hitachi Research Laboratory, Hitachi, Ltd. (reference) 4E067 AA05 BG00 DA13 DA17 DC07 EA04 EA07 EB00 5H011 AA01 AA09 BB03 CC06 DD12 5H029 AJ11 AJ14 AK05 AL13 AM15 BJ02 BJ16 CJ05 EJ01 DJ07 DJ07 DJ07 DJ07

Claims (6)

[Claims] 1. A negative electrode container constituting a negative electrode chamber containing sodium, and a positive electrode container constituting a positive electrode chamber containing a positive electrode active material composed of sulfur, selenium, tellurium, sodium polysulfide or / and metal chloride, In a sodium secondary battery provided with a solid electrolyte separating the negative electrode chamber / the positive electrode chamber, the negative electrode container and / or the positive electrode container is friction stir welded with a plurality of aluminum metal plates or aluminum alloy metal plates. The metal plates having different thicknesses bonded to each other are used for the friction stir welding from inside the metal plate having the thicker thickness at a position distant from the friction stir welding part. A sodium secondary battery characterized in that the rotating tool that was used is pulled out. 2. The sodium secondary battery according to claim 1, wherein the plate thickness of the one metal plate joined by friction stir welding is twice or more the plate thickness of the other metal plate. 3. The plate according to claim 1, wherein a metal plate forming a negative electrode lid which is a part of the negative electrode container has a plate thickness of a metal plate forming a negative electrode body part and a negative electrode flange which are a part of the negative electrode container. Greater than the thickness, and / or the plate thickness of the metal plate forming the positive electrode lid that is a part of the positive electrode container is a plate of the metal plate forming the positive electrode body or the positive electrode flange that is a part of the positive electrode container. A sodium secondary battery characterized by being larger than the thickness. 4. A negative electrode container forming a negative electrode chamber containing sodium, and a positive electrode container forming a positive electrode chamber containing a positive electrode active material made of sulfur, selenium, tellurium, sodium polysulfide or / and metal chloride, In a sodium secondary battery provided with a solid electrolyte in which the negative electrode chamber / the positive electrode chamber are separated from each other, a vacuum suction provided on a metal plate forming a negative electrode lid, a negative electrode body or a negative electrode flange which is a part of the negative electrode container. Or gas pressure control through hole, and / or a vacuum plate or gas pressure control through hole provided on a metal plate forming a positive electrode lid, a positive electrode body or a positive electrode flange which is a part of the positive electrode container. The hole is sealed by friction stir welding, the plate thickness of the metal plate is larger than the inner diameter of the through hole, and the rotary tool used for the friction stir welding is performed from inside the metal plate at a position distant from the through hole. Draw Sodium secondary battery, characterized by being unplugged. 5. The collector according to claim 1, wherein an aluminum or aluminum alloy current collector is provided along the solid electrolyte in the positive electrode container, and the current collector constitutes the positive electrode container. A sodium secondary battery, which is joined to a positive electrode lid and / or a positive electrode body. 6. The sodium secondary battery according to claim 1 or 4, wherein the solid electrolyte is a solid electrolyte bag tube, and the solid electrolyte bag tube is arranged in a horizontal or oblique direction. .