JPH08185889A - Sodium-sulfur battery - Google Patents

Abstract

PURPOSE: To easily control the quality of sodium and ensure high stability as well as long service life by providing the bottom of a negative electrode vessel with a thermal fuse sealed sodium flow port, and a safety tube projected from the vessel and having a sodium filling port. CONSTITUTION: A safety tube 3 has a sodium flow port 9 sealed with a thermal fuse material on the bottom, and a sodium filling port 5 extended from the top, and is formed to be capsule type. The tube 3 is filled with sodium from the filling port 5. The filling port 5 is, then, sealed and the tube 3 is housed in a solid electrolyte 2. Thereafter, heat is applied at a level exceeding the fusing point of the thermal fuse material, thereby melting the material and causing sodium to be in contact with the electrolyte. According to this construction, the quality control of battery elements such as a β''Al2 O3 tube can be easily made, including the control of sodium purity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sodium / sulfur battery, which relates to a sodium / sulfur battery, which is highly stable and has a long service life, and is easy to mass-produce.

[0002]

2. Description of the Related Art Sodium / sulfur batteries have a temperature of 300 to
When operated at 400 ° C, when the battery is discharged, sodium, which is the negative electrode active material, becomes an ion and passes through β ″ -Al ₂ O ₃ , and reacts with the positive electrode active material sulfur as shown in the following formula (1) to polysulfide. Sodium (hereinafter abbreviated as Na ₂ Sx, X = 3 to 5)
Generate During charging, the reverse battery reaction occurs, producing sulfur at the positive electrode and metallic sodium at the negative electrode.

2Na + xS → Na ₂ Sx (1) Conventionally, when manufacturing a sodium / sulfur battery, the battery was semi-assembled and then sodium was collected (so-called supply) (Japanese Patent Laid-Open No. 2-213061). Also, put sodium in the container in which the capsule is formed and seal the nozzle etc. at the end of the capsule, fold the sealed nozzle when assembling the capsule into a battery, fold it from the root, and expose the hole after folding. After that, assembling the battery is described (JP-A-4-206272).

[0004]

In the case of a comparative battery (FIG. 6) having a sodium supply hole in a safety tube, when sodium is vacuum-injected into a subassembly of the battery, sodium is generated. Sodium is supplied from the sodium supply hole of the safety pipe to the space 7b between the β ″ -Al ₂ O ₃ pipe and the safety pipe, that is, to the upper 7 ′ of the heat-pressure contact portion where the positive and negative electrodes are separated and insulated. This sodium is supplied to the upper part of the gap while cleaning the inside of the safety pipe, the wick and the surface of the gap part, so that considerably contaminated sodium adheres to the hot press contact part, etc. During the operation of the battery, the sodium surface However, the oxide in the form of a film remains adhered or exists as an oxide film on the liquid surface, which may cause corrosion of the hot press contact area.

According to this method, the hot press contact portion, β ″ -Al ₂ O ₃
It is difficult to control the quality of element materials such as pipe and sodium purity. Also, as in JP-A-4-206272, when assembling the battery after assembling the battery after folding the nozzle of the end of the capsule containing sodium before the root and exposing the hole after folding, Since the reactivity is high, a reaction product of sodium may occur near the sodium flow hole due to contact with outside air. Due to the nature of sodium, it is necessary to suppress the reaction between sodium and the outside air as much as possible.

Further, when the safety tube is directly joined to the negative electrode container, it is difficult to center it when the safety tube is accommodated in the electrolyte tube, and due to the eccentricity of the β ″ -Al ₂ O ₃ tube, the welding distortion of the safety tube is caused. A stress load is applied to the β ″ -Al ₂ O ₃ tube due to deterioration of verticality due to the above and thermal strain.

Further, by simply assembling and joining the negative electrode container and the safety tube, it is difficult to disassemble and treat a used battery or a defective battery, and it is not easy to reuse the negative electrode active material including the safety tube. . Further, sodium and sulfur have a property of easily reacting when one of sodium and sulfur melts. When this directly reacts, in the adiabatic state, the temperature rises to about 1400 to 2000 ° C,
Since it is dangerous, it is necessary to separate and treat sodium and sulfur, but the battery structure was difficult to separate. In the above-mentioned conventional technology, it is difficult to control the quality of sodium and the like, and it is not easy to extend the life of the battery.

In view of the above matters, the present invention is to provide a sodium / sulfur battery which is capable of easily controlling the quality of sodium, has high stability, and has a long life. Further, it is easy to mass-produce the battery. / To provide a sulfur battery.

[0009]

In order to achieve the above object, a sodium / sulfur battery safety tube is encapsulated,
The connecting tube to the negative electrode container is a narrow tube made by Velose,
This is achieved by using a battery structure, a sodium collecting method, and a battery assembling method for collecting sodium of the negative electrode active material in which the sodium supply hole at the bottom is once closed with a thermal fuse.

In a battery configuration in which a positive electrode having sulfur and a negative electrode having sodium are provided with a solid electrolyte having sodium ion conductivity (hereinafter, abbreviated as β ″ -Al ₂ O ₃ ), sodium of the negative electrode active material is encapsulated. It is characterized in that the safety tube is once enclosed and then assembled into a battery structure.

The present invention is arranged between a positive electrode container containing a positive electrode active material made of sulfur or sodium polysulfide, a negative electrode container containing a negative electrode active material made of sodium, and the positive electrode portion and the negative electrode portion. A solid electrolyte having sodium ion conductivity, an insulating portion for insulating the positive electrode container and the negative electrode container from each other, sodium contained in the negative electrode container and containing sodium sealed at the bottom thereof with a temperature fuse material. It is characterized by comprising a flow hole and a safety tube having a sodium injection port sealed at the top thereof and projecting from the negative electrode container. The negative electrode container of the negative electrode part may be connected to the insulating material.

Further, the negative electrode container of the negative electrode portion is connected to the insulating material, the safety pipe is composed of a sodium containing portion and a sodium injection pipe, and the negative electrode container is connected to the sodium injection pipe and the sodium injection pipe. The tube is characterized by having a stress relaxation mechanism between the connection part and the sodium containing part. As the stress relaxation mechanism, for example, bellows can be used. As the bellows, a chevron-shaped thick tube or the like can be used. The end of the injection tube has a sodium injection port.
Alternatively, it is possible to use a structure in which the diameter or wall thickness of the tube is reduced to facilitate deformation.

Due to the structure having the bellows at the position,
By having a structure that improves flexibility in vertical and horizontal movement of the safety tube, rather than having a bellows in the negative electrode container,
"reduce the stress load on the -Al ₂ O ₃ tube, β" β -Al ₂
The action of suppressing the destruction of the O ₃ tube can be improved. As a result, a highly stable battery can be made, which can contribute to a longer life. Also, because the injection pipe has a bellows structure,
The safety tube can be positioned only by the injection tube having the bellows structure. Therefore, the safety tube can be easily positioned and the safety tube can be positioned more easily than the one in which the elastic member is simply connected to the upper portion of the safety pipe or the one in which the elastic member and the support member are arranged on the opposite side of the safety pipe. By adopting a configuration that is supported only by the injection tube, the bellows can be easily deformed, and when the battery is assembled, even if the solid electrolyte tube has a poor bonding position accuracy, it can be assembled as a battery, It is possible to suppress stress concentration and the like in the solid electrolyte.

The injection tube may be a thin tube having a bellows. It is preferably about 1/4 to 1/6 of the diameter of the safety pipe. Further, it is preferable that a sodium supply hole is provided at the bottom of the sodium accommodating portion of the safety pipe, and the sodium is supplied to the electrolyte by closing it with a temperature fuse and melting it at an operating temperature or lower.

Further, the positive electrode container is made of Fe--Cr alloy
Alloys with l can be used. Further, as the solid electrolyte, one having high bending strength can be used.
For example, it can be 300 to 700 MPa. Sn, Pb, Ag, Cd, Sb, Zn in the sodium
The component having at least one of the above is a melted thermal fuse arranged in the sodium flow hole of the safety pipe. The positive electrode container has, for example, Cr: 25 to 27% by weight, A
1: 1 to 5% by weight, balance Fe, and preferably 1% by weight or less of C. Or even more, Mo is 1
Preferably, it is contained in an amount of about 5% by weight. The solid electrolyte preferably has the above bending strength. The solid electrolyte may have an average particle size of about several μm to several tens (for example, 20) μm. With this configuration, for example, when operating for 1200 hours per year, 1200 hours per discharge, and 6360 hours off, the battery efficiency (charging / discharging efficiency) after 10 years is 8
It is intended to achieve an efficiency of 5% or more.

The thermal fuse material is made of Sn, Pb,
It is characterized by being a metal or alloy containing at least one of Ag, Cd, Sb, and Zn.

Further, a positive electrode part having a positive electrode container containing a positive electrode active material made of sulfur or sodium polysulfide, a negative electrode part having a negative electrode container containing a negative electrode active material made of sodium, the positive electrode part and the negative electrode part. And a solid electrolyte having sodium ion conductivity disposed between the positive electrode container and the negative electrode container, and an insulating part for insulating the positive electrode container and the negative electrode container, containing sodium in the negative electrode part, and having a sodium flow hole. The sodium / sulfur battery provided with a safety tube is characterized in that the sodium contains at least one of Sn, Pb, Ag, Cd, Sb and Zn having a solubility of 2 ppm or more and not more than 2 ppm at 350 ° C. in sodium. Those containing the above components in the above range can be operated in a battery without inhibiting the battery reaction of the sodium / sulfur battery. The component may be a melted thermal fuse. The measurement location is
It is preferable to measure by taking sodium at the center of the safety pipe, near the inner surface of the safety pipe, and in the gap between the safety pipe and the solid electrolyte. The component in the sodium is Sn, P
It is preferable to have at least two of b, Ag, Cd, Sb, and Zn. It is easy to fabricate a thermal fuse that melts above the sodium sampling temperature and below the sodium operating temperature. Furthermore, it is preferable that the thermal fuse has at least Sb. For example, if Sb is included,
Reacts with oxygen (Na ₂ O, etc.) in sodium to form a compound (oxide), further purifies sodium, prevents reduction of the amount that contributes to battery reaction, and improves performance of sodium / sulfur battery Can be achieved.

Sn, Pb, Ag, C in the sodium
It is better to contain a component containing at least one of d, Sb, and Zn in an amount of 1% by weight or less, and it is preferable to further contain 2 to 60 ppm. More preferably, the component in sodium is Sn, Pb, Ag,
It is preferable to include a component having at least two of Cd, Sb, and Zn. Furthermore, it is preferable to contain at least Sb.

The components such as Sn, Pb, Ag, Cd, Sb, and Zn are the amounts capable of closing the sodium flow holes of the safety pipe.

The method for producing a sodium / sulfur battery according to the present invention is characterized in that a sodium safety hole having a sodium flow hole sealed with a temperature fuse material at the bottom and a sodium injection port extended to the top thereof is used to safely discharge sodium from the injection port. The method is characterized by including a step of injecting into the tube, a step of sealing the injection port, and a step of accommodating the safety tube in a solid electrolyte. According to the method of the present invention, a solid electrolyte tube that is highly deteriorated or highly reactive in the air and the quality control of sodium are easy, and a sodium / sulfur battery with high quality can be efficiently produced. sodium/
The manufacturing process of the sulfur battery can be shortened, and the manufacturing cost of the battery can be reduced.

In particular, this method allows the solid electrolyte tube to be stored until the final assembly of the battery.

Further, after the safety tube is housed in the solid electrolyte, it is heated to a temperature higher than the melting point of the thermal fuse to melt the thermal fuse and bring the sodium into contact with the solid electrolyte. It is characterized by In the present invention, since it is not necessary to remove the temperature fuse attached to the safety tube at the time of assembling the battery, the temperature of the battery is raised after the battery is assembled, and the sodium sealed in the safety tube is replaced with the solid electrolyte or the like. Since sodium is contacted, it can be produced without contact with the atmosphere in the production process, so that deterioration of highly reactive sodium can be prevented more efficiently. The ingredients can be melted in sodium when the temperature is raised as described above. The thermal fuse is composed of Sn, Pb, Ag,
It is preferable to have at least two components of Cd, Sb, and Zn and to melt them into sodium by heating.

According to the present invention, a positive electrode portion containing a positive electrode active material made of sulfur or sodium polysulfide, a negative electrode portion containing a negative electrode active material made of sodium, and a positive electrode portion disposed between the positive electrode portion and the negative electrode portion. In a sodium / sulfur battery safety tube for a sodium / sulfur battery having a solid electrolyte having sodium ion conductivity and containing sodium in the positive electrode part and having a sodium flow hole, the safety tube is at the bottom. It is characterized by having a sodium flow hole sealed with a temperature fuse material and a sodium injection port extended to the top thereof. Further, preferably, the safety pipe is composed of a sodium containing portion and a sodium injection pipe, and the injection pipe has a bellows and a portion for connecting the negative electrode portion on an end side of the bellows.

It is preferable that a sodium supply hole closed by a thermal fuse is provided at the bottom of the sodium containing portion of the safety pipe to supply sodium to the safety pipe at a sodium temperature of 150 to 200 ° C.

According to the present invention, since it is possible to evacuate and collect sodium through one end of the sodium injection pipe, it is possible to easily evacuate and control the amount of sodium collected.

The flow holes are made of Sn, Pb, Ag, C.
It is characterized in that a plug of a thermal fuse having a component containing at least one of d, Sb and Zn is arranged.

Preferably, Sn, P is added to the sodium.
It is preferably composed of a component having at least two of b, Ag, Cd, Sb and Zn.

The thermal fuse may be melted at a temperature below the operating temperature of the sodium / sulfur battery.

The temperature fuse is Sn5-15-Pb8.
5-95 wt%, Sn5-20-Pb80-95 wt
%, Ag5-25-Pb95-97.5 wt%, Ag3
~ 5-Cd95-97wt%, Cd32-90-Zn1
A material having at least one of 0 to 68 wt% and Pb97 to 99-Sb1 to 3 wt% and melting at 250 to 350 ° C. can be used.

The thermal fuse preferably contains Sb.

Further, according to the present invention, a positive electrode portion containing a positive electrode active material made of sulfur or sodium polysulfide, a negative electrode portion containing a negative electrode active material made of sodium, and a space between the positive electrode portion and the negative electrode portion. In the sodium collecting device for collecting sodium into a safety tube for sodium / sulfur batteries, which comprises a solid electrolyte having sodium ion conductivity arranged and which contains sodium in the negative electrode part and which has a sodium flow hole, The pipe is composed of a sodium container and a sodium injection pipe, and a plug of a temperature fuse that melts at a sodium / sulfur battery operating temperature is arranged in the flow hole, and has a sodium sampling port connected to the end of the injection pipe. The sampling port is a decompression device that decompresses the inside of the sodium containing portion through the sampling port, and the sampling port is the inside of the decompressed sodium containing portion. Sodium accumulating tank that, characterized in that it is contacted to the city.

Further, the safety pipe is composed of a sodium containing portion and a sodium injection pipe having a stress relaxation mechanism (bellows, etc.), and the negative electrode portion is provided in the injection pipe portion on the end side of the stress relaxation mechanism. A connection valve is provided, and a switching valve for switching the flow path between the sampling port and the decompression device or the sodium tank, and the sodium injection pipe are closed between the sampling port and the decompression device or the sodium tank. It is characterized by having a closing device.

By collecting sodium into the safety pipe of the present invention by using the sodium sampling device and manufacturing the sodium / sulfur battery of the present invention, the sodium can be manufactured without being exposed to the atmosphere in the manufacturing process, so that the performance is deteriorated. Can be prevented.

The closure device may be a device for collecting sodium into a safety pipe and then caulking a predetermined portion near the end of the sodium injection pipe to seal it. After collecting sodium, the collecting port is preferably closed before being separated from the sodium injection tube. Other than the caulking, other means may be used as long as the opening of the sodium injection tube can be sealed.

According to the present invention, a vacuum is drawn through one sampling port,
Sodium can be collected, so you can easily evacuate,
It is easy to control the amount of sodium collected.

In the present invention, sulfur, a positive electrode part having a positive electrode container containing the sulfur, and a negative electrode part having sodium and a negative electrode container containing the sodium are arranged via a solid electrolyte having sodium ion conductivity, The negative electrode container of the positive electrode part is connected to the insulating material, and the sodium / sulfur battery including a safety tube that contains sodium in the solid electrolyte in the negative electrode container and has a sodium flow hole can be applied.

[0037]

According to the present invention, it is possible to provide a sodium / sulfur battery in which the quality control of sodium is easy, the stability and the life of the battery can be improved, and the sodium / sulfur battery is easily mass-produced. it can.

The negative electrode active material sodium is easily collected,
And the prevention of contamination from the atmosphere at the time of assembling the collection time and the battery of sodium and beta "can include -Al ₂ O ₃ tube like component parts of the quality control. In addition, beta" stress on -Al ₂ O ₃ tube The load can be reduced, the quality control of the element materials such as β ″ -Al ₂ O ₃ tube and sodium can be facilitated, the assembly process of the battery can be simplified and the safety can be improved, and the dismantling and treatment of the used battery, Alternatively, the reuse of sodium can be facilitated, and the manufacturing cost of the battery can be reduced.

In the present invention, since it is not necessary to remove the temperature fuse attached to the safety tube when assembling the battery, the temperature of the battery is raised after the battery is assembled and the sodium sealed in the safety tube is solidified. Since sodium is produced without contact with the atmosphere in the production process because it is brought into contact with the electrolyte or the like, deterioration of highly reactive sodium can be prevented more efficiently. Highly reactive sodium produces Na ₂ O, NaOH and H ₂ when it comes into contact with water or oxygen. Sodium is so active that it reacts with water and oxygen for a few seconds to produce the reactants. For this reason, it is important to control the atmosphere in contact with sodium, and in some cases, it is necessary to work in a container or the like in which moisture and oxygen are suppressed to low levels, which makes handling difficult and the workability is poor.

Since Na ₂ O has a very high melting point (about 1270 ° C.), it does not melt at the battery operating temperature and remains in the battery. At that time, if the sodium flow holes or the like are blocked or the sodium flow is obstructed, the battery performance may be deteriorated, and it may be a cause of preventing the life extension. Also,
NaOH is highly corrosive, and may deteriorate the electrolyte or the like and may corrode the negative electrode container or the like. Further, if H ₂ having high reactivity is present in the battery, hydrogen embrittlement of the metal material and deterioration of the solid electrolyte tube are unfavorable.

According to the present invention, it is possible to carry out the steps from collecting sodium in a sodium container to assembling the battery and operating the battery without touching the sodium with the outside air. The life can be extended.

According to the present invention, the oxygen concentration in sodium can be suppressed, and the production of reactants such as Na ₂ O can also be suppressed, so that a good battery can be obtained.

According to the present invention, when operating for 1200 hours per year, 1200 hours per discharge, and 6360 hours off, 1
It aims to achieve a battery efficiency (charge / discharge efficiency) of 85% or more after 0 years.

Specifically, the sodium-sulfur battery of the present invention has a sodium-filled hole at the bottom of the safety tube, which is closed with a temperature fuse, and has a bellows-made thin tube structure at the connection with the upper negative electrode container. By collecting the sodium of the negative electrode active material into the tube, (1) the quality control of the β ″ -Al ₂ O ₃ tube and the purity control of sodium are easy, and (2) the connection between the negative electrode container and the safety tube is made into a thin tube. -"
-Reduce the stress load on the Al ₂ O ₃ tube to improve the safety of the battery, (3) the safety tube and the sodium of the negative electrode active material can be reused, and (4) the dismantling process of used batteries and failed batteries. There are merits such as being easy.

[0045]

Embodiments of the present invention will be described below.

Example 1 FIG. 1 is a sectional view of a sodium / sulfur battery showing this example. 1 is a positive electrode container, 2 is a solid electrolyte, 3 is a safety tube (sodium containing part), 4 is a positive electrode terminal, 5 is a sodium injection tube (negative electrode terminal), 6 is positive,
Α-Al ₂ O ₃ joint for separating and insulating the negative electrode, 7 is sodium, 8 is a sulfur mold, 9 is a sodium supply hole,
Reference numeral 10 is a negative electrode container, and 11 is a thin tube made of bellows.

FIG. 2 is a vertical sectional view of the capsule-shaped safety pipe. 3 is a safety tube, 5 is a sodium injection tube (negative terminal),
7 is sodium, 9 is a sodium supply hole closed with a thermal fuse, 11 is a bellows thin tube, 12 is a flange (a portion for joining with the negative electrode part (negative electrode container)), and 13 is a sealing part. It is a semi-crushed tube for sealing after collecting sodium in the tube. Reference numeral 14 is a sodium sampling port, and 15 is a sodium supply pipe.

FIG. 5 is a cross-sectional view of a comparative sodium / sulfur battery. 1 is a positive electrode container, 2 is a sodium ion conductive solid electrolyte, 3 is a safety tube, 4 is a positive electrode terminal, 5 is a negative electrode terminal which also serves as a sodium introducing tube, 6 is α-alumina for separating and insulating positive and negative electrodes (Hereinafter, abbreviated as α-Al ₂ O ₃ ) Joined portion (hereinafter, abbreviated as hot press contact portion), 7 is negative electrode active material sodium, 8 is a sulfur mold in which carbon felt is impregnated with positive electrode active material S, and 9 is sodium. Supply hole and 10
Is a negative electrode container.

In this battery structure, the negative electrode active material sodium was collected by providing a sodium supply hole of 0.1 to 1.0 mmφ at the bottom of the safety tube. Fig. 6 shows a safety tube, β ″ -Al ₂ through the α-Al ₂ O ₃ ring of the comparative sodium / sulfur battery.
O ₃ and shows a semi-assembled view of the anode container. As shown in the figure, α-Al ₂ O ₃ is attached to the safety pipe 3 welded to the negative electrode container 10.
Sodium is vacuum-injected from the sodium injecting tube 5 into a shape in which the β ″ -Al ₂ O ₃ tube 2 is attached via the ring 6, that is, a subassembly of the battery. Sodium is supplied from the sodium supply hole of the safety pipe to the portion between the β ″ -Al ₂ O ₃ pipe and the safety pipe, that is, to the portion 7 ′ above the positive and negative isolation heat-insulating joints of the positive and negative electrodes above the gap. Is supplied. Since this sodium is supplied to the upper part of the gap while cleaning the inside of the safety pipe, the wick and the surface of the gap, considerably contaminated sodium adheres to the hot press contact part and the like. Although the liquid level of sodium decreases during the operation of the battery, the film-shaped oxide remains attached or exists as an oxide film on the liquid surface. Also, at 350 ° C, which is the rated operating temperature of sodium / sulfur batteries, the solubility of oxygen in sodium is approximately 200 ppm, so the amount of oxygen above this is the amount of heat-bonded portion that initially adhered, or , Remains on the liquid surface. Corrosion of the material in the liquid sodium depends on the oxygen concentration in the sodium, so there is a risk of corrosion even in the hot press contact portion of the battery. Since the battery of the present invention can suppress these corrosions, it can have good performance.

In the comparative battery, it is known that when sodium is sucked into a thin tube by a vacuum suction method, the inner surface of the tube is washed and impurities are carried to the rear side of the tube and segregated. It is speculated that the phenomenon is occurring.

(1) As described above, β ″ -Al ₂ O
After assembling ₃ tubes, safety tube, α-Al ₂ O ₃ ring, negative electrode container, etc., to perform sodium sampling operation, heat press contact part, β ″ -Al ₂ O ₃ tube and sodium purity etc. Quality control is difficult.

(2) Since the safety pipe has a welded structure directly on the flange of the negative electrode container, centering is difficult,
Combined with the eccentricity of the β ″ -Al ₂ O ₃ pipe, the verticality is impaired due to welding strain of the safety pipe, and thermal strain causes a stress load on the β ″ -Al ₂ O ₃ pipe, resulting in β ″ -A
It is considered to be one of the causes of damage to the l ₂ O ₃ tube.

(3) When collecting sodium in the safety tube, the safety tube, the negative electrode container and the β ″ -Al ₂ O ₃ tube are joined together through an α-Al ₂ O ₃ ring for separating and insulating the positive and negative electrodes. In addition, since sodium is collected in the so-called semi-assembled form of the battery, there are often batteries with insufficient sodium filling.

(4) As described in (2) above, the flange of the negative electrode container and the safety pipe have a welded structure, and it is a battery structure in which it is difficult to disassemble and process used batteries and defective batteries. It is not easy to reuse the negative electrode active material. Further, sodium and S have a property of easily reacting when one of sodium and S melts. Then, when this directly causes a reaction, in the adiabatic state, approximately 1400 to 2
It becomes a high temperature of 000 ℃, and it is dangerous, so sodium and S
It was necessary to separate and treat the battery, but the battery structure was difficult to separate. The battery of the present invention can solve these problems.

Further, the used battery and the defective battery have a battery structure that can be easily cut from the negative electrode container part, the safety tube is drawn out, sodium and S are separated, and disassembled and processed.

By using a bellows thin tube as the connecting pipe between the safety pipe and the negative electrode container, the safety pipe is pulled out from the β ″ -Al ₂ O ₃ pipe only by cutting or separating a predetermined part of the negative electrode container portion. It is possible to reuse the safety tube and sodium.

Since the positive electrode active material is separated as S and the negative electrode active material is separated as metallic sodium, it is preferable to stop the battery at the end of charging.

Example 2 An assembly process for the above battery will be described. Sn5-15-Pb8 which melts at 250-350 degreeC in the sodium supply hole 9 of the safety pipe 3 which welded the flange part of the bellows of FIG.
5-95 wt%, Ag2.5-Pb97.5 wt%, Sn
5-20-Pb80-95 wt% and Ag5-Cd95
Sodium is collected by a vacuum injection method into a material that is closed using a low melting point alloy such as wt%. At this time, the sampling temperature of sodium is 150 to 200 ° C.

In addition, the closing of the sodium supply hole at the bottom of the safety pipe by the temperature fuse causes the sodium supply hole to be small.
Since the safety tube has a large heat capacity, heat it up to near the melting point of the thermal fuse used to close the sodium supply hole before performing the test.

[0060] After collecting the sodium to the above safety tube, then, β "-Al ₂ O ₃ tube and to what positive electrode container is connected, the safety tube sodium was taken β" -Al ₂ O ₃
The cell structure is completed by inserting the tube and joining it to the positive electrode side.

The amount of the thermal fuse such as Pb-Sn, Ag-Pb alloy used for closing the sodium supply hole was about 0.02 g even if the total amount was converted to Pb.
The concentration in sodium is about 60 wtppm, and the solubility of Pb in sodium at 330 ° C is 1
Since it is about 2 wt%, there is no particular problem.
As described above, the process of collecting the negative electrode active material sodium and the battery assembling are simple, and since the β ″ -Al ₂ O ₃ tube is attached at the final stage of the battery assembly, the β ″ -Al ₂ O ₃ tube is used. It can prevent scratches and cracks, and can be assembled without being contaminated with impurities or dust. Therefore, the quality control of the battery element material such as the β ″ -Al ₂ O ₃ tube including the sodium purity control is facilitated.

Example 3 Bending of β ″ -Al ₂ O ₃ tube,
As a measure to alleviate the stress load on the β ″ -Al ₂ O ₃ tube, such as eccentricity and bending of the safety tube, and the stress generated during battery operation, (1) bellows the upper part of the safety tube shown in Fig. 2. Attached to the negative electrode container as a thin tube made of steel, (2) a safety tube of 3- (a) in FIG. 3, a bellows attached to the upper part of the product, and (3) a wave in the negative electrode container of 3- (b) in FIG. Structure for attaching plate-shaped bellows and (4) 3- (c) in FIG.
A structure in which a bellows is attached to the body of the negative electrode container can be considered.

As described above, various stress relaxation methods are conceivable. However, it is often unknown in the battery that the mechanism of stress generation such as the directionality and magnitude of stress is complicated. Therefore, it is necessary to be able to instantly respond to small and sudden stresses generated in the battery.
For that purpose, the battery structure in which the connection tube between the safety tube and the negative electrode container shown in FIG. 2 is a bellows thin tube is most effective β ″.
-It is possible to prevent damage to the Al ₂ O ₃ tube.

As described above, the sodium injection tube having the bellows connecting the safety tube and the negative electrode container portion can immediately cope with a small generated stress or a sudden generated stress in the battery,
Moreover, since it is necessary to make the tube diameter so that sodium can be easily collected, it is desirable that the diameter is approximately 1/4 to 1/6 of the safety tube diameter.

(Embodiment 4) Since the safety tube is made into a capsule shape, sodium can be collected by the safety tube alone, and the sodium collecting portion is simple and the collecting method is simple, so that the insufficient filling of sodium is solved. . FIG. 4 shows a sodium collecting device for a safety pipe. 3 is a safety tube, 7 is sodium, and 13 is a sealing part. After collecting sodium into the safety tube, the tube is crimped to make it easy to seal, a half-crushed tube, 16 is a tank for supplying sodium, and 17 is a sodium solution. Area meter, 18 is a sodium measuring tank, 19 is a valve,
20 is a sodium inlet pipe from the sodium purifier,
21 is a sodium outlet pipe. The procedure for collecting sodium in the safety pipe with this device is described below.

Sodium purifier and sodium tank 1
6 is connected by pipes 20 and 21, and after circulating and refining sodium, the required amount is measured by the liquid level gauge 17, and the valve 19 is stopped. Then, the vacuum suctioned sodium is once collected in the measuring tank 18. As the safety pipe, a sodium injection pipe is connected through a sodium sampling port, a valve 19-2 on the vacuum pump side is opened, the sodium containing portion is evacuated by the vacuum pump, and then the valve 19-2 is closed and the valve 19 is opened. Inject sodium. After that, although not explicitly shown in the drawing, it is preferable that a part of the sodium injection tube is caulked and sealed.

As described above, sodium can be easily collected into a large number of safety tubes at one time, and since it is sealed in a metal container and can be stored for a long period of time, mass production of batteries is possible.

(Example 5) FIG. 7 shows an example of an apparatus for collecting sodium. Since the same operation is performed when sodium is collected from many safety tubes at the same time, only one safety tube is shown. 30 is a sealing device. For example, a device for crimping the end of the sodium injection tube. Reference numeral 14 denotes a sampling port, which may be a swaging lock. The capacity of the sodium measuring tank 18 in this apparatus is the required amount of sodium to be collected in the safety pipe 3.

First, the heater 2 is connected to the entire sodium system of the apparatus.
5 was added to adjust the temperature to 150 to 220 ° C., the valves 19-1 and 19-2 of the sodium tank 16 were opened, the sodium purification device was connected, and the sodium was purified and circulated. Is measured and valves 19-1 and 19 are
-2 is closed. Next, the valves 19-5 and 19-6 are opened, the vacuum pump 23 is operated to evacuate the safety pipe 3 and the sodium measuring tank 18, and the valves 19-7 and 19-8 are operated from the Ar gas supply system 24. To supply Ar gas to perform vacuum-Ar gas replacement to clean the inside,
Vacuum the safety pipe 3 and the sodium measuring tank 18,
Valves 19-5 and 19-6 are closed. With valve 19-9 closed, gently open valve 19-3 and then valve 19-4,
Sodium was introduced into the sodium measuring tank 18, and the valve 1
9-4 and then the valve 19-3 are closed in this order. And valve 19
Open -9 and collect sodium in safety tube 3.

After closing the valve 19-9 and lowering the temperature of the safety pipe to the melting point of sodium (97.5 ° C.) or lower to solidify the sodium, the sealing portion 13 is sealed with a sealing device (for example, caulking device). After crimping well, remove the safety tube. It is preferable that the sodium adhering to the sodium injection tube end port of the safety tube is washed with ethyl alcohol or the like and sealed.

As described above, according to the present invention, the connection between the safety tube and the negative electrode container is a bellows thin tube, and the sodium supply hole is once closed with a temperature fuse to form a capsule shape. Resolution, β ″ -Al
The quality control of element materials such as ₂ O ₃ pipes is easy, and β ″
It is possible to provide a highly safe sodium / sulfur battery capable of reducing the stress load on the —Al ₂ O ₃ tube and reusing the negative electrode active material.

Example 6 Sodium as the negative electrode active material was
A purity of 99.5% or more can be used. In this case, the oxygen concentration in sodium is about 10 ppm. Furthermore, in the battery, oxygen flows out into the sodium from the oxides on the surface of the safety tube and the surface of the β ″ -Al ₂ O ₃ tube, so the oxygen concentration in the sodium is about 1 in the battery.
It may be about 00 to 200 ppm. When the operating condition of a sodium / sulfur battery is 350 ° C., the solubility of oxygen in sodium may be about 220 ppm. Therefore, when more oxygen is dissolved in sodium, the corrosion rate increases with the increase of oxygen, and when oxygen having a solubility or higher is present, supersaturated oxygen (present as Na ₂ O etc.) precipitates and precipitates to form sodium. There is also a risk of obstructing the flow of sodium in the supply hole or blocking it. In addition, the battery performance may be reduced.

Therefore, it is preferable to suppress contact with oxygen and moisture as much as possible when handling the battery element material and assembling the battery.

Further, since the corrosion rate of the material in contact with sodium is influenced by the oxygen concentration in sodium, it is preferable to eliminate the cause of the increase in oxygen concentration in sodium.

FIG. 8 is a graph showing the relationship between the oxygen concentration in sodium and the corrosion rate of stainless steel (SUS304). This figure shows the relationship between the oxygen concentration and the corrosion rate at a sodium temperature of 400 ° C (10% to 20% lower than the data in this figure when the battery operating condition is 350 ° C). .
In the battery, the oxygen concentration in sodium becomes about 100 to 200 ppm by being mixed into the sodium from the surface of the safety tube or the solid electrolyte tube. The rate of corrosion of the safety pipe and the like is about 20 to 100 μm / year. Temporarily 2
If we take 00ppm, for example, if the corrosion progresses linearly during the target service life of the battery of 10 years, it will be about 1000.
Since μm is corroded and the material strength is greatly reduced, it is important to suppress the mixing of oxygen into sodium due to other factors.

For example, stainless steel (SUS3 used for safety pipes
04) has relatively good coexistence with sodium, but Al and Al brazing material (Al surface) at the joint between sodium-sulfur battery constituent materials α-alumina and other members. A material containing about 10% Si in 20 to 30 μm) is used, and as the oxygen concentration in sodium increases, the rate of corrosion increases, so it is important to control the purity of the negative electrode active material sodium. Has become.

According to the present invention, (1) it is possible to eliminate the insufficient filling of the negative electrode active material sodium, (2) easy quality control such as β ″ -Al ₂ O ₃ tube and sodium purity, and (3) disassembly of used batteries. , Simplification of processing, (4) High safety, due to the battery structure that can relieve the stress on the β ″ -Al ₂ O ₃ tube
It can provide long life battery. (5) Sodium can be collected and stored in a safety tube in advance, which facilitates mass production of battery. (6) Both safety tube can reuse sodium as negative electrode active material. In addition, the manufacturing cost of the battery can be reduced.

[0078]

According to the present invention, it is possible to provide a sodium / sulfur battery in which the quality control of sodium is easy, and which is highly stable and has a long service life. A sulfur battery can be provided.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a sodium / sulfur battery showing an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a capsule-shaped safety pipe showing a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of a stress relaxation example showing the third, fourth and fifth embodiments of the present invention.

FIG. 4 is a schematic view of an embodiment of a collection device for collecting sodium in a safety pipe of the present invention.

FIG. 5 is a longitudinal sectional view of a comparative sodium / sulfur battery.

FIG. 6 is a semi-assembled view of a safety tube, β ″ -Al ₂ O ₃ and a negative electrode container through an α-Al ₂ O ₃ ring of a comparative sodium / sulfur battery.

FIG. 7 is a schematic view of an embodiment of a collection device for collecting sodium in a safety pipe of the present invention.

FIG. 8 is a diagram showing the relationship between the oxygen concentration in sodium and the corrosion rate of stainless steel.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Positive electrode container, 2 ... Solid electrolyte, 3 ... Safety tube, 4 ... Positive electrode terminal, 5 ... Sodium injection tube (negative electrode terminal), 6 ... Alpha-A
l ₂ O ₃ joint, 7, 7 '... Sodium, 8 ... Sulfur mold, 9 ... Sodium supply hole, 9' ... Sodium supply hole and temperature fuse, 10 ... Negative electrode container, 11 ... Bellows, 1
2 ... Flange, 13 ... Sealing part, 14 ... Sodium collection port, 15 ... Sodium supply pipe, 16 ... Sodium tank, 17 ... Sodium level gauge, 18 ... Sodium measuring tank, 19 ... Valve, 20 ... Sodium purification device Connecting pipe
(Inlet), 21 ... Connection pipe (outlet) with sodium purification device, 23 ... Vacuum pump, 24 ... Ar gas system, 25 ... Heater, 30 ... Sealing device, 31 ... Sodium inlet.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuo Kawasaki 72-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Energy Research Laboratory

Claims (12)

[Claims] 1. A positive electrode part having a positive electrode container containing a positive electrode active material made of sulfur or sodium polysulfide, a negative electrode part having a negative electrode container containing a negative electrode active material made of sodium, the positive electrode part and the negative electrode part. A solid electrolyte having sodium ion conductivity, which is arranged between the positive electrode container and the negative electrode container, and an insulating portion which insulates the positive electrode container and the negative electrode container from each other. A sodium / sulfur battery, comprising a sealed sodium flow hole and a safety tube having a sodium injection port which is sealed on the top and projects from the negative electrode container. 2. The sodium / sulfur battery according to claim 1, wherein the negative electrode container is connected to the insulating material, the safety pipe comprises a sodium container and a sodium injection pipe, and the negative electrode container is the sodium injection pipe. The sodium / sulfur battery, wherein the sodium injection pipe has a stress relaxation mechanism between the connection portion and the sodium storage portion. 3. The sodium / sulfur battery according to claim 1, wherein the temperature fuse material is Sn, Pb, Ag, Cd, S.
A sodium / sulfur battery, which is a metal or alloy containing at least one of b and Zn. 4. A positive electrode part having a positive electrode container containing a positive electrode active material made of sulfur or sodium polysulfide, a negative electrode part having a negative electrode container containing a negative electrode active material made of sodium, the positive electrode part and the negative electrode part. And a solid electrolyte having sodium ion conductivity disposed between the positive electrode container and the negative electrode container, and an insulating part for insulating the positive electrode container and the negative electrode container, containing sodium in the negative electrode part, and having a sodium flow hole. In a sodium / sulfur battery provided with a safety tube, the sodium contains at least one of Sn, Pb, Ag, Cd, Sb, and Zn having a solubility of 2 ppm or more in sodium at 350 ° C. battery. 5. A step of injecting sodium into the safety pipe from the injection port into a safety pipe having a sodium flow hole sealed at the bottom with a thermal fuse material and a sodium injection port extending to the top thereof, A method of manufacturing a sodium / sulfur battery, comprising a step of sealing and a step of accommodating the safety tube in a solid electrolyte. 6. The method for manufacturing a sodium / sulfur battery according to claim 5, wherein after the safety tube is housed in a solid electrolyte,
A method of manufacturing a sodium / sulfur battery, comprising the step of heating the temperature fuse to a temperature higher than the melting point of the temperature fuse to melt the temperature fuse and bringing the sodium into contact with a solid electrolyte. 7. A positive electrode portion containing a positive electrode active material made of sulfur or sodium polysulfide, a negative electrode portion containing a negative electrode active material made of sodium, and sodium arranged between the positive electrode portion and the negative electrode portion. In a sodium / sulfur battery safety tube for a sodium / sulfur battery having a solid electrolyte having ion conductivity, wherein sodium is accommodated in the positive electrode part and has a sodium flow hole, the safety tube is provided with a thermal fuse at the bottom. A sodium / sulfur battery safety tube having a sodium flow hole sealed with a material and a sodium injection port extended to the top thereof. 8. The safety pipe for a sodium / sulfur battery according to claim 7, wherein the safety pipe comprises a sodium containing portion and a sodium injection pipe, and the injection pipe has a stress relaxation mechanism, and an end of the stress relaxation mechanism. A sodium / sulfur battery safety pipe, characterized in that it has a portion for connecting to the negative electrode portion on the side of the portion. 9. The safety pipe for sodium / sulfur batteries according to claim 7 or 8, wherein the temperature fuse melts at an operating temperature of the sodium / sulfur battery or lower. 10. The safety pipe for a sodium / sulfur battery according to claim 8, wherein the temperature fuse is Sn5 to 15-Pb8.
5-95 wt%, Sn5-20-Pb80-95 wt
%, Ag5-25-Pb95-97.5 wt%, Ag3
~ 5-Cd95-97wt%, Cd32-90-Zn1
A safety tube for a sodium / sulfur battery, which has at least one of 0 to 68 wt% and Pb97 to 99-Sb1 to 3 wt% and melts at 250 to 350 ° C. 11. A positive electrode portion containing a positive electrode active material made of sulfur or sodium polysulfide, a negative electrode portion containing a negative electrode active material made of sodium, and sodium arranged between the positive electrode portion and the negative electrode portion. Sodium having a solid electrolyte having ion conductivity and having sodium flow holes /
In a sodium collecting device for collecting sodium into a safety battery for a sulfur battery, the safety pipe comprises a sodium container and a sodium injection pipe, and the flow hole is provided with a plug of a temperature fuse that melts at a sodium / sulfur battery operating temperature. And has a sodium sampling port connected to the end of the injection pipe, the sampling port decompressing the inside of the sodium container through the sampling port, and sampling in the depressurized sodium container. And a sodium tank for storing sodium, which is in communication with a sodium collecting device. 12. The sodium collecting apparatus according to claim 11, wherein the safety pipe comprises a sodium containing portion and a sodium injection pipe having a stress relaxation mechanism, and the negative electrode is provided in the injection pipe portion on an end side of the stress relaxation mechanism. And a switching valve for switching the flow path between the sampling port and the decompression device or the sodium tank between the sampling port and the decompression device or the sodium tank, and the sodium injection pipe. A sodium collecting device having a sealing device for sealing the.