JP3265883B2 - Sodium / sulfur battery - Google Patents

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, and more particularly, to a sodium / sulfur battery capable of achieving high stability and a long life and being easily mass-produced.

[0002]

2. Description of the Related Art A sodium / sulfur battery has a temperature of 300-300.
The battery is operated at 400 ° C., and when the battery is discharged, sodium, which is a negative electrode active material, becomes an ion, passes through β ″ -Al ₂ O ₃ , reacts with sulfur of the positive electrode active material as shown in the following formula (1), and becomes 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 a sodium / sulfur battery is manufactured, sodium is collected (so-called supply) after the battery is in a semi-assembled state (Japanese Patent Laid-Open No. 2-130661). In addition, sodium is put into the container in which the capsule is formed, and the nozzle at the end of the capsule is sealed, and when the capsule is assembled into a battery, the sealed nozzle is attached and folded from the root to expose the folded hole. After that, assembling a battery is described (JP-A-4-206272).

[0004]

In the case of a battery having a sodium supply hole in a safety tube such as a comparative battery (FIG. 6), when sodium is vacuum-injected into a semi-assembled battery, the sodium becomes Sodium is supplied from the sodium supply hole of the safety tube to the space between the β ″ -Al ₂ O ₃ tube and the safety tube, that is, to the upper part 7 ′ of the separated and insulated thermal pressure contact part of the positive and negative electrodes above the gap. Since this sodium is supplied to the upper portion of the gap portion while cleaning the inside of the safety pipe, the wick and the surface of the gap portion, considerably contaminated sodium adheres to the heat welding portion, etc. During the operation of the battery, the liquid level of the sodium 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 heat-pressed portion.

In this method, a heat-pressed portion, β ″ -Al ₂ O ₃
It is difficult to control the quality of element materials such as tubes and sodium purity. Also, as in Japanese Patent Application Laid-Open No. 4-206272, before assembling, after assembling a battery after attaching a nozzle or the like at the end of the capsule containing sodium and exposing the hole after folding to expose the hole after folding, as in JP-A-4-206272. Since the reactivity is high, there is a possibility that a reactant of sodium may be generated near the sodium flow hole due to contact with the outside air. Due to the nature of sodium, it is necessary to suppress the reaction between sodium and outside air as much as possible.

Further, when the safety tube is directly joined to the negative electrode container, it is difficult to align the safety tube in the electrolyte tube, and the eccentricity of the β ″ -Al ₂ O ₃ tube causes the welding distortion of the safety tube. For example, a stress load is applied to the β ″ -Al ₂ O ₃ tube due to impaired verticality and thermal strain.

Further, it is difficult to disassemble and dispose of a used battery or a failed battery simply by assembling and joining the anode container and the safety tube, and it is not easy to reuse the anode active material including the safety tube. . In addition, sodium and sulfur have a property of easily reacting when one of sodium and sulfur is melted. When this causes a direct reaction, in an adiabatic state, the temperature becomes approximately 1400 to 2000 ° C.,
Because of the danger, it is necessary to separate and treat sodium and sulfur, but the battery structure is difficult to separate. In the above prior art, quality control of sodium or the like is difficult, and it is not easy to extend the life of the battery.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a sodium / sulfur battery in which the quality of sodium can be easily controlled, high stability and long life can be achieved, and a sodium / sulfur battery which can be easily mass-produced. / Sulfur battery.

[0009]

In order to achieve the above object, a safety tube of a sodium / sulfur battery is encapsulated,
The connection tube to the negative electrode container is a bellows-made thin tube.
This can be achieved by using a battery structure for collecting the negative electrode active material sodium, a sodium collecting method, and a battery assembling method, in which the bottom sodium supply hole 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 ), the negative electrode active material sodium is encapsulated. It is characterized in that it is once sealed in a safety tube alone and then assembled into a battery configuration.

The present invention provides 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 disposed between 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, and sodium disposed in the negative electrode container and containing sodium and sealed at the bottom with a thermal fuse material. And a safety tube having a sodium inlet sealed at the top of the through hole and protruding from the negative electrode container. The negative electrode container of the negative electrode section 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 tube comprises a sodium storage portion and a sodium injection tube, and the negative electrode container is connected to the sodium injection tube, The pipe is characterized by having a stress relaxation mechanism between the connection part and the sodium storage part. As the stress relaxation mechanism, for example, a bellows can be used. As the bellows, a tubular member having a thick mountain shape can be used. The end of the injection tube has a sodium inlet.
Alternatively, it is also possible to use a structure in which the diameter or thickness of the tube is reduced to facilitate deformation.

According to the structure having the bellows at the position,
By having a structure with improved flexibility in vertical and horizontal movement of the safety tube, than with a bellows in the negative electrode container,
"reduce the stress load on the -Al ₂ O ₃ tube, β" β -Al ₂
The effect of suppressing the destruction of the O ₃ tube can be improved. As a result, a highly stable battery can be obtained, which can contribute to a longer life. In addition, because the injection tube has a bellows structure,
The positioning of the safety pipe can be performed only with the injection pipe having the bellows structure. Therefore, it is easier to position the safety pipe than when the elastic member is simply connected to the upper part of the safety pipe, or when a support member or the like is arranged on the opposite side of the elastic member and the safety pipe, and the safety pipe is easy to use. By adopting the configuration supported only by the injection tube, the bellows can be easily deformed, and when assembling the battery, even when the joining position accuracy of the solid electrolyte tube is not good, it can be assembled as a battery, It is possible to suppress the occurrence of stress concentration or the like in the solid electrolyte.

[0014] The injection tube may be a thin tube having a bellows. It is preferable that the diameter of the safety pipe is approximately 1/4 to 1/6. Preferably, a sodium supply hole is provided at the bottom of the sodium storage portion of the safety tube, closed with a temperature fuse, melted at an operating temperature or lower to supply sodium to the electrolyte.

[0015] Further, the positive electrode container is made of an Fe-Cr alloy with A
An alloy having 1 can be used. Further, the solid electrolyte 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 obtained by melting the thermal fuse disposed in the sodium flow hole of the safety tube. The positive electrode container is, for example, Cr: 25 to 27% by weight, A
l: 1 to 5% by weight, with the balance being Fe, and preferably containing 1% by weight or less of C. Or, in addition, Mo
Preferably, it is contained in an amount of about 5% by weight. Preferably, the solid electrolyte has the bending strength described above. The solid electrolyte may have an average particle size of about several μm to several tens (eg, 20) μm. With this configuration, for example, when the battery is operated for 1200 hours of charging, 1200 hours of discharging, and 6360 hours of suspension, the battery efficiency (charge / discharge efficiency) after 10 years is 8
An efficiency of 5% or more is achieved.

The thermal fuse material is composed of Sn, Pb,
It is a metal or an alloy having at least one of Ag, Cd, Sb, and Zn.

Also, a positive electrode portion having a positive electrode container containing a positive electrode active material made of sulfur or sodium polysulfide, a negative electrode portion having a negative electrode active material containing a negative electrode active material made of sodium, the positive electrode portion and the negative electrode A solid electrolyte having sodium ion conductivity disposed between the positive electrode container and the negative electrode container. The negative electrode container contains sodium, and the bottom has a thermal fuse. Lumber
Equipped with a safety tube with a sodium flow hole sealed with
Then, dissolve the thermal fuse material and add
In a sodium / sulfur battery supplying lithium,
The thermal fuse must be melted after melting the thermal fuse.
Of Sn, Pb, Ag, Cd, Sb, Zn contained in the
Content at 2ppm or more and at 350 ° C
Metal or alloy with a composition and amount that is less than the solubility of
It is characterized by being gold . A battery containing the above components in the above range can operate the battery without inhibiting the battery reaction of the sodium / sulfur battery. The component may be a melted thermal fuse. It is preferable to measure sodium 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 components in the sodium are Sn, Pb, A
It is preferable to have at least two of g, Cd, Sb, and Zn. Easily manufactured thermal fuse dissolves below the operating temperature of the sodium higher than taking the temperature of sodium.
For example, if Sb or the like is contained, oxygen in sodium
(Na ₂ O, etc.) to form a compound (oxide),
By further purifying sodium, it is possible to prevent a decrease in the amount contributing to the battery reaction and improve the performance of the sodium / sulfur battery.

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

Components such as Sn, Pb, Ag, Cd, Sb, and Zn are in an amount capable of closing the sodium flow hole of the safety tube.

According to the method for manufacturing a sodium / sulfur battery of the present invention, sodium is safely supplied from a safety tube having a sodium flow hole sealed with a thermal fuse material at the bottom and a sodium injection port extending at the top. It is characterized by including a step of injecting into the tube, a step of sealing the inlet, and a step of housing the safety tube in a solid electrolyte. According to the method of the present invention, it is easy to control the quality of solid electrolyte tubes and sodium, which have high degradation and reactivity in the air, and a high-quality sodium / sulfur battery can be efficiently obtained. sodium/
The manufacturing process of the sulfur battery can be shortened, and the manufacturing cost of the battery can be reduced.

In particular, in the present method, the solid electrolyte tube can be stored until the final assembly of the battery.

Still further, the method further comprises a step of heating the safety tube to a temperature higher than the melting point of the thermal fuse after the safety tube is housed in the solid electrolyte, melting the thermal fuse, and bringing the sodium into contact with the solid electrolyte. It is characterized by the following. In the present invention, it is not necessary to remove the thermal fuse attached to the safety tube when assembling the battery.Therefore, after assembling the battery, the temperature of the battery is raised, and the sodium sealed in the safety tube is replaced with a solid electrolyte or the like. Since the contact is made, sodium can be produced without coming into contact with the atmosphere in the production process, so that deterioration of highly reactive sodium can be prevented more efficiently. When the temperature is raised as described above, the components can be dissolved in sodium. The thermal fuse is composed of Sn, Pb, Ag,
It is preferable to have at least two or more components of Cd, Sb, and Zn and to melt them into sodium by heating.

According to the present invention, there is provided 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 disposed between the positive electrode portion and the negative electrode portion. A sodium / sulfur battery provided with a solid electrolyte having sodium ion conductivity, a sodium / sulfur battery safety tube containing sodium in the positive electrode portion and having a sodium circulation hole, wherein the safety tube is provided at the bottom. It is characterized by having a sodium flow hole sealed with a thermal fuse material and a sodium injection port extending at the top thereof. Preferably, the safety tube includes a sodium storage portion and a sodium injection tube, and the injection tube has a bellows and a portion for connecting the negative electrode portion at an end portion side of the bellows.

It is preferable that a sodium supply hole closed with a thermal fuse is provided at the bottom of the sodium storage portion of the safety tube, and sodium is supplied to the safety tube at a sodium temperature of 150 to 200 ° C.

According to the present invention, vacuum evacuation and sodium collection can be performed through one end of the sodium injection tube, so that vacuum evacuation can be easily performed and the amount of sodium collected can be easily controlled.

The flow holes are formed of Sn, Pb, Ag, C
A plug for a thermal fuse having a component having at least one of d, Sb, and Zn is provided.

Preferably, Sn, P is contained in the sodium.
It is preferable to comprise a component having at least two of b, Ag, Cd, Sb, and Zn.

Further, the thermal fuse is characterized by melting below the operating temperature of the sodium / sulfur battery.

The thermal fuse is Sn5-15-Pb8
5-95wt%, Sn5-20-Pb80-95wt
%, Ag5-25-Pb95-97.5 wt%, Ag3
95 to 97 wt%, Cd32 to 90-Zn1
A material having at least one of 0 to 68 wt% and Pb 97 to 99-Sb 1 to 3 wt% and melting at 250 to 350 ° C. can be used.

The thermal fuse preferably contains Sb.

Further, the present invention provides 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 gap between the positive electrode portion and the negative electrode portion. A solid electrolyte having sodium ion conductivity disposed therein, wherein the sodium is contained in the negative electrode portion, and the sodium is collected in a sodium / sulfur battery safety tube having a sodium flow hole. The tube comprises a sodium storage portion and a sodium injection tube, and the flow hole is provided with a temperature fuse plug which melts at the operating temperature of the sodium / sulfur battery, and has a sodium sampling port connected to the end of the injection tube. The sampling port is provided with a decompression device for reducing the pressure in the sodium container through the sampling port, and the pressure is collected in the decompressed sodium container. Sodium accumulating tank that, characterized in that it is contacted to the city.

Further, the safety tube comprises a sodium accommodating portion and a sodium injection tube having a stress relaxation mechanism (bellows or the like), and the injection tube portion on the end side of the stress relaxation mechanism is connected to the negative electrode portion. It has a connecting portion, and between the sampling port and the pressure reducing device or the sodium tank, a switching valve for switching a flow path between the sampling port and the pressure reducing device or the sodium tank, and closing the sodium injection pipe. It is characterized by having a closing device.

By collecting sodium in the safety tube of the present invention using the sodium collecting apparatus and manufacturing the sodium / sulfur battery of the present invention, the sodium can be produced without contact with the atmosphere in the production process, so that the performance is deteriorated. Can be prevented.

[0034] The closing device may be a device that collects sodium into the safety tube, and then caulks and seals a predetermined portion near an end of the sodium injection tube. Preferably, after the sodium is collected, the port is closed before the port is separated from the sodium injection tube. In addition to 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, the evacuation is performed through one sampling port.
Since sodium can be collected, vacuum can be easily drawn,
It is easy to control the amount of sodium collected.

According to the present invention, a positive electrode portion having sulfur and a positive electrode container containing the sulfur, and a negative electrode portion having sodium and a negative electrode container containing the sodium are disposed via a solid electrolyte having sodium ion conductivity. The negative electrode container of the positive electrode part is connected to the insulating material, and accommodates sodium in the solid electrolyte in the negative electrode container, and is applicable to a sodium / sulfur battery provided with a safety tube having a sodium circulation hole.

[0037]

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

To facilitate the collection of the negative electrode active material sodium,
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 of element materials such as β ″ -Al ₂ O ₃ tube and sodium can be easily controlled, the battery assembly process can be simplified, safety can be improved, and the disassembly and processing of used batteries can be improved. Alternatively, sodium can be easily reused, and the manufacturing cost of the battery can be reduced.

In the present invention, it is not necessary to remove the thermal fuse attached to the safety tube when assembling the battery. Therefore, after assembling the battery, the temperature of the battery is raised, and the sodium sealed in the safety tube is solidified. Since it is brought into contact with an electrolyte or the like, sodium can be produced without coming into contact with the atmosphere in the production process, so that 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 moisture or oxygen. Sodium is so active that contact with moisture or oxygen for only a few seconds produces a reactant. For this reason, it is important to control the atmosphere that comes into contact with sodium, and in some cases, it is necessary to work in a container or the like in which moisture and oxygen are kept at a low level, and handling is difficult and 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 this time, if the sodium flow holes or the like are closed or the flow of sodium is obstructed, it will cause a decrease in battery performance and will also hinder a longer life. Also,
NaOH is extremely corrosive, and may degrade the electrolyte and the like and corrode the negative electrode container and the like. Further, if highly reactive H ₂ is interposed in the battery, it is not preferable because hydrogen embrittlement of the metal material and deterioration of the solid electrolyte tube occur.

According to the present invention, from the collection of sodium in the sodium container to the battery assembly and operation of the battery, the sodium can be performed without contact with the outside air, so that the above-mentioned corrosion deterioration and the like can be suppressed, and high stability and long life can be achieved. Life can be extended.

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

According to the present invention, when the battery is operated for 1200 hours of charging, 1200 hours of discharging, and 6360 hours of suspension per year,
The battery efficiency (charge / discharge efficiency) after 85 years is 85% or more.

Specifically, the sodium supply hole at the bottom of the safety tube of the sodium / sulfur battery of the present invention is closed with a thermal fuse, and the connection with the upper negative electrode container is formed in a bellows-made thin tube structure. By collecting the negative electrode active material sodium into the tube, (1) quality control of the β ″ -Al ₂ O ₃ tube and purity control of sodium are easy, and (2) the connecting portion between the negative electrode container and the safety tube is formed by a thin tube. − ″, Β ″
-Al ₂ improve safety relief to cell stress load on the O ₃ tube, (3) can be reused safely tube and the negative electrode active material of sodium, and (4) slaughter of used batteries or breakdown battery There are merits such as being easy.

[0045]

Embodiments of the present invention will be described below.

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

FIG. 2 is a longitudinal sectional view of the capsule-shaped safety pipe. 3 is a safety tube, 5 is a sodium injection tube (negative electrode terminal),
7 is sodium, 9 is a sodium supply hole closed with a thermal fuse, 11 is a bellows-made thin tube, 12 is a flange (part 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. 14 is a sodium sampling port and 15 is a sodium supply pipe.

FIG. 5 is a 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 also serving as a sodium introduction tube, 6 is α-alumina for separating and insulating the positive and negative electrodes. (Hereinafter abbreviated as α-Al ₂ O ₃ ) joint (hereinafter abbreviated as heat-pressed portion), 7 is a negative electrode active material sodium, 8 is a sulfur mold obtained by impregnating carbon felt with a positive electrode active material S, 9 is sodium Supply hole and 10
Denotes a negative electrode container.

In the present battery configuration, a sodium supply hole of 0.1 to 1.0 mmφ was provided at the bottom of the safety tube for collecting the negative electrode active material sodium. FIG. 6 shows a safety tube, β ″ -Al ₂ through the α-Al ₂ O ₃ ring of the comparative sodium / sulfur battery.
FIG. ₃ shows a semi-assembled drawing of O ₃ and a negative electrode container. As shown in the figure, the safety tube 3 welded to the negative electrode container 10 has α-Al ₂ O ₃
Sodium is vacuum-injected from the sodium injection tube 5 into a configuration in which the β ″ -Al ₂ O ₃ tube 2 is attached via the ring 6, that is, a semi-assembled battery. Sodium is transferred from the sodium supply hole of the safety tube to the portion between the β ″ -Al ₂ O ₃ tube and the safety tube, that is, to a portion 7 ′ above the positively and negatively separated thermal pressure welding portions of the positive and negative electrodes above the gap. Is supplied. Since this sodium is supplied to the upper portion of the gap portion while cleaning the inside of the safety pipe, the wick and the surface of the gap portion, considerably contaminated sodium adheres to the heat-welded portion and the like. During the operation of the battery, the liquid level of sodium drops, but the oxide in the form of a film remains attached or exists as an oxide film on the liquid level. Further, at the rated operating temperature of the sodium / sulfur battery of 350 ° C., the solubility of oxygen in sodium is approximately 200 ppm. And remains on the liquid surface. Since the corrosion of the material in liquid sodium depends on the oxygen concentration in sodium, there is a possibility that the material may be corroded even at the heat-welded portion of the battery. Since the battery of the present invention can suppress such corrosion, it can have good performance.

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

(1) As described above, β ″ -Al ₂ O
After assembling the _three pipes, safety pipe, α-Al ₂ O ₃ ring, negative electrode container, etc., in order to carry out the operation of collecting sodium, element materials such as heat welding parts, β ″ -Al ₂ O ₃ pipe and sodium purity Quality control is difficult.

(2) Since the safety pipe is directly welded to the flange of the negative electrode container, it is difficult to center the pipe.
In combination with the eccentricity of the β ″ -Al ₂ O ₃ pipe, the verticality is impaired due to welding distortion of the safety pipe, and thermal stress causes stress load on the β ″ -Al ₂ O ₃ pipe. "-A
This is considered to be one of the causes of damage to the l ₂ O ₃ tube.

(3) When sodium is collected in the safety tube, the safety tube, the negative electrode container and the β ″ -Al ₂ O ₃ tube are joined via an α-Al ₂ O ₃ ring for separating and insulating the positive and negative electrodes. In order to collect sodium in a so-called semi-assembled form of the battery, there is often an underfilled sodium battery.

(4) As described in the above (2), the flange of the negative electrode container and the safety tube have a welded structure, and it is difficult to disassemble and dispose of a used battery or a failed battery. 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 is melted. When this causes a direct reaction, in an adiabatic state, it is almost 1400 to 2
The temperature rises to 000 ° C, which can be dangerous.
Must be separated and processed, but the battery structure is difficult to separate. The battery of the present invention can solve these problems.

Further, the used battery and the failed battery have a battery structure which can be cut off from the negative electrode container part, a safety tube is pulled out, sodium and S are separated, and disassembly processing and disposal are easy.

Since the connecting pipe between the safety tube and the negative electrode container is a thin tube made of bellows, the safety tube is pulled out from the β ″ -Al ₂ O ₃ tube only by cutting or separating a predetermined portion of the negative electrode container portion. The safety tube and sodium can be recycled.

It is preferable that the battery be stopped at the end of charging in order to separate the positive electrode active material as S and the negative electrode active material as metallic sodium.

(Example 2) An assembling process for the above battery will be described. Sn5-15-Pb8 that melts at approximately 250-350 ° C. in the sodium supply hole 9 of the safety tube 3 in which the flange portion of the bellows of FIG. 2 is welded to the negative electrode container.
5-95 wt%, Ag2.5-Pb97.5 wt%, Sn
5-20-Pb 80-95 wt% and Ag5-Cd95
Sodium is collected by a vacuum injection method into a closed one using a low melting point alloy such as wt%. At this time, the sampling temperature of sodium is set at 150 to 200 ° C.

Further, when the sodium supply hole at the bottom of the safety tube is closed by a thermal fuse, the sodium supply hole is small.
Since the heat capacity of the safety tube is large, it is necessary to heat it up to near the melting point of the thermal fuse used to close the sodium supply hole.

After sodium was collected in the above-mentioned safety tube, the safety tube from which sodium was collected was connected to the β ″ -Al ₂ O ₃ tube and the positive electrode container connected to the β ″ -Al ₂ O ₃ tube.
It is inserted into the tube and joined to the positive electrode side to complete the battery configuration.

The amount of the thermal fuse such as Pb-Sn or Ag-Pb alloy used for closing the sodium supply hole is about 0.02 g even if the total amount is converted to Pb.
The concentration in sodium is approximately 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 anode active harvested and cell assembly process materials sodium is simple, also, "for attaching -Al ₂ O ₃ tube, beta" final stage beta assembly of battery -Al ₂ O ₃ tube Can be prevented, and can be assembled without being contaminated by impurities or dust. For this reason, the quality control of the battery element materials such as the β ″ -Al ₂ O ₃ tube including the control of the purity of sodium is facilitated.

Example 3 Bending of β ″ -Al ₂ O ₃ tube,
Measures to alleviate the stress load on the β ″ -Al ₂ O ₃ tube, such as eccentricity, bending of the safety tube, and stress generated during battery operation, are as follows: (1) Bellows the upper part of the safety tube shown in FIG. (2) A structure in which a bellows is attached to the upper part of the safety tube itself shown in 3- (a) of FIG. 3 and (3) A wave is attached to the negative 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 negative electrode container body is considered.

As described above, various stress relaxation methods are conceivable, but in a battery, it is often unknown that the mechanism of stress generation, such as the direction and magnitude of stress, is complicated. Therefore, it is necessary to be able to respond instantaneously to small or sudden generated stress in the battery.
For this purpose, a battery structure in which the connection pipe between the safety pipe and the negative electrode container shown in FIG.
-Breakage of the Al ₂ O ₃ tube can be prevented.

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

(Example 4) Since the safety tube is made into a capsule shape, sodium can be collected by the safety tube alone, and the sodium collection section is simple and the collection method is simple, so that insufficient filling of sodium is eliminated. . FIG. 4 shows a device for collecting sodium into a safety tube. Reference numeral 3 denotes a safety tube, 7 denotes sodium, 13 denotes a sealing portion, which is a half-crushed tube which collects sodium into the safety tube, and then caulks the tube to facilitate sealing, 16 denotes a tank for supplying sodium, and 17 denotes a sodium liquid. Surface gauge, 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 into a safety tube using this device is described below.

Sodium refining device and sodium tank 1
6 is connected by pipes 20 and 21 and after sodium is circulated and purified, the required amount is measured by a liquid level gauge 17 and the valve 19 is stopped. Next, sodium which has been previously vacuum-suctioned is once collected in the measuring tank 18. The safety pipe is connected to the sodium injection pipe through the sodium sampling port, opens the valve 19-2 on the vacuum pump side, evacuates the sodium container with the vacuum pump, closes the valve 19-2, and opens the valve 19. Inject sodium. Thereafter, although not explicitly shown in the figure, it is preferable that a part of the sodium injection tube is caulked and sealed.

As described above, sodium can be easily collected in a large number of safety tubes at once, and sealed in a metal container, and can be stored for a long time, so that mass production of batteries is possible.

(Embodiment 5) FIG. 7 shows an example of an apparatus for collecting sodium. Since the same operation is performed when sodium is simultaneously sampled from a large number of safety tubes, only one safety tube is sampled. Reference numeral 30 denotes a sealing device. For example, a device for caulking the end of a sodium injection tube. 14 is a sampling port, which may be like a swaging lock. The capacity of the sodium measuring tank 18 in the present apparatus is a necessary amount of sodium collected in the safety pipe 3.

First, the entire sodium system of the apparatus was
5, the temperature is set to 150 to 220 ° C., the valves 19-1 and 19-2 of the sodium tank 16 are opened to connect with the sodium purifier, and the sodium is purified and circulated. Are measured and valves 19-1 and 19
-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. Ar gas is supplied to perform vacuum-Ar gas replacement to clean the inside,
The inside of the safety pipe 3 and the sodium measuring tank 18 is evacuated,
The valves 19-5 and 19-6 are closed. With the valve 19-9 closed, the valve 19-3 and then the valve 19-4 are gently opened,
Sodium is introduced into the sodium measuring tank 18 and the valve 1
9-4, and then close the valve 19-3 in that 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 tube below the melting point of sodium (97.5 ° C.) to solidify the sodium, the sealing portion 13 is sealed with a sealing device (for example, a caulking device). Using a crimping method, remove the safety tube. It is preferable that the sodium adhered to the end of the sodium injection pipe of the safety pipe be 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 made of a bellows-made thin tube, and the sodium supply hole is made into a capsule shape once closed by a temperature fuse, thereby preventing insufficient filling of sodium. Elimination, β ″ -Al
Quality control of element materials such as ₂ O ₃ pipes can be easily performed.
Such reuse reduces and the negative electrode active material of the stress load on the -al ₂ O ₃ tube can provide a highly secure sodium / sulfur battery possible.

(Example 6) The sodium of the negative electrode active material was
Those having a purity of 99.5% or more can be used. In this case, the oxygen concentration in sodium is about 10 ppm. Further, in the battery, oxygen flows out from the oxide or the like on the surface of the safety tube and the surface of the β ″ -Al ₂ O ₃ tube into the sodium, so that the oxygen concentration in the sodium in the battery is about 1%.
It may be about 00 to 200 ppm. When the operating condition of the sodium / sulfur battery is, for example, 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 an increase in oxygen. When oxygen having a solubility higher than that is present, supersaturated oxygen (existing as Na ₂ O) precipitates and precipitates, and There is a possibility that the flow of sodium through the supply hole may be hindered or blocked. In addition, there is a possibility that the battery performance is reduced.

Therefore, it is preferable to minimize contact with oxygen and moisture when handling battery element materials and assembling batteries.

Since the corrosion rate of a material that comes into contact with sodium is affected by the oxygen concentration in sodium, it is preferable to eliminate the cause of the increase in oxygen concentration in sodium.

FIG. 8 shows the relationship between the oxygen concentration in sodium and the corrosion rate of stainless steel (SUS304). This graph shows the relationship between the oxygen concentration and the corrosion rate at a sodium temperature of 400 ° C. (when the battery operating condition is 350 ° C., the value is about 10 to 20% lower than the data in this graph). .
In the battery, the oxygen concentration in the sodium by mixing into the sodium from the surface of the safety tube or the solid electrolyte tube is about 100 to 200 ppm. The rate at which the safety pipe and the like are corroded is approximately 20 to 100 μm / year. If the upper limit is 2
For example, assuming that the corrosion progresses linearly in the target service life of the battery for 10 years, about 1000 ppm is assumed.
μm is corroded, and the material strength is greatly reduced. Therefore, it is important to prevent oxygen from being mixed into sodium due to other factors.

For example, stainless steel (SUS3
04) and the like have relatively good coexistence with sodium, but Al and Al brazing material (Al surface) are used at the joint between α-alumina, which is an insulating material, of sodium / sulfur battery components and other members. A material containing about 10% of Si in 20 to 30 μm) is used. When the oxygen concentration in sodium increases, the rate of corrosion increases accordingly. Therefore, it is important to control the purity of the negative electrode active material sodium. It has become.

According to the present invention, (1) the insufficient filling of the negative electrode active material sodium can be eliminated, (2) quality control such as β ″ -Al ₂ O ₃ tube and sodium purity can be easily performed, and (3) dismantling of used batteries. , Simplification of processing, and (4) a battery structure capable of relieving the stress on the β ″ -Al ₂ O ₃ tube provides high safety,
It can provide a long-life battery. (5) It is possible to collect sodium in a safety tube in advance and store it, and it is easy to mass-produce the battery. This has the effect of reducing the battery manufacturing cost.

[0078]

According to the present invention, it is possible to provide a sodium / sulfur battery in which the quality of sodium can be easily controlled, high stability and long life can be provided, and sodium / sulfur battery which can be easily mass-produced. A sulfur battery can be provided.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal 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 third, fourth and fifth embodiments of the present invention.

FIG. 4 is a schematic diagram of one embodiment of a sampling device for sampling sodium in a safety tube according to 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 via an α-Al ₂ O ₃ ring of a comparative sodium / sulfur battery.

FIG. 7 is a schematic view of an embodiment of a sampling device for collecting sodium in a safety tube according to the present invention.

FIG. 8 is a graph 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 ... α-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 sampling port, 15 ... Sodium supply pipe, 16 ... Sodium tank, 17 ... Sodium level gauge, 18 ... Sodium measuring tank, 19 ... Valve, 20 ... Sodium refining device Connecting pipe
(Inlet), 21: connecting pipe (outlet) to sodium refining device, 23: vacuum pump, 24: Ar gas system, 25: heater, 30: sealing device, 31: sodium inlet.

Continued on the front page (72) Inventor, Naohisa 7-2-1, Omika-cho, Hitachi, Ibaraki Pref. Energy Research Laboratory, Hitachi, Ltd. (72) Inventor Katsuo Kawasaki 7-2-1, Omika-cho, Hitachi, Ibaraki Shares (56) References JP-A-5-205774 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 10/39 H01M 10/54

Claims (12)

(57) [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, an insulating portion for insulating the positive electrode container and the negative electrode container, and sodium disposed in the negative electrode container and having a bottom formed with a thermal fuse material. A sodium / sulfur battery comprising: a sealed sodium flow hole; and a safety tube having a sodium inlet sealed at the top and protruding from the negative electrode container. 2. The sodium / sulfur battery according to claim 1, wherein said negative electrode container is connected to said insulating material, said safety tube comprises a sodium container and a sodium injection tube, and said negative electrode container is said sodium injection tube. A sodium / sulfur battery, wherein the sodium injection tube has a stress relaxation mechanism between the connection portion and the sodium storage portion. 3. The sodium / sulfur battery according to claim 1, wherein said thermal fuse material comprises Sn, Pb, Ag, Cd, S
A sodium / sulfur battery characterized by being a metal or an alloy having at least one of b and Zn. 4. A positive electrode portion having a positive electrode container containing a positive electrode active material comprising sulfur or sodium polysulfide, a negative electrode portion having a negative electrode container containing a negative electrode active material comprising sodium, the positive electrode portion and the negative electrode portion , A solid electrolyte having sodium ion conductivity and an insulating portion for insulating the positive electrode container and the negative electrode container. The negative electrode portion contains sodium, and the bottom has a thermal fuse material. Sealed in
A safety tube having a through hole for sodium,
Melt the fuse material and supply sodium to the solid electrolyte.
In the supplied sodium / sulfur battery,
Is contained in sodium after melting of the thermal fuse.
Sn, Pb, Ag, Cd, Sb, Zn content
Dissolution of sodium at 2ppm or more and at 350 ° C
This is a composition and amount of metal or alloy such that less degrees
And a sodium / sulfur battery. 5. A step of injecting sodium into the safety tube from the inlet into a safety tube having a sodium flow hole sealed at the bottom with a thermal fuse material and an extended sodium inlet at the top. A method for manufacturing a sodium / sulfur battery, comprising a step of sealing and a step of housing the safety tube in a solid electrolyte. 6. A method for manufacturing a sodium / sulfur battery according to claim 5, wherein said safety tube is housed in a solid electrolyte.
A method for manufacturing a sodium / sulfur battery, comprising a step of melting the thermal fuse by heating to a temperature higher than a melting point of the thermal fuse and bringing the sodium into contact with a solid electrolyte. 7. A positive electrode section containing a positive electrode active material comprising sulfur or sodium polysulfide, a negative electrode section containing a negative electrode active material comprising sodium, and sodium disposed between the positive electrode section and the negative electrode section. In a sodium / sulfur battery having a solid electrolyte having ion conductivity, a sodium / sulfur battery safety tube containing sodium in the positive electrode portion and having a sodium circulation hole, wherein the safety tube has a thermal fuse at the bottom. A safety tube for a sodium / sulfur battery, characterized by having a sodium flow hole sealed with a material and a sodium injection port extending at the top thereof. 8. A safety tube for a sodium / sulfur battery according to claim 7, wherein said safety tube comprises a sodium storage portion and a sodium injection tube, said injection tube having a stress relaxation mechanism, and an end of said stress relaxation mechanism. A safety tube for a sodium / sulfur battery, comprising a connection portion for connecting to the negative electrode portion on the side of the safety tube. 9. The safety tube for a sodium / sulfur battery according to claim 7, wherein the thermal fuse melts at a temperature lower than an operating temperature of the sodium / sulfur battery. 10. A safety tube for a sodium / sulfur battery according to claim 8, wherein said thermal fuse is Sn5-15-Pb8.
5-95wt%, Sn5-20-Pb80-95wt
%, Ag5-25-Pb95-97.5 wt%, Ag3
95 to 97 wt%, Cd32 to 90-Zn1
A safety tube for a sodium / sulfur battery, comprising at least one of 0 to 68 wt% and Pb97 to 99-Sb1 to 3 wt% and melting at 250 to 350 ° C. 11. A positive electrode part containing a positive electrode active material made of sulfur or sodium polysulfide, a negative electrode part containing a negative electrode active material made of sodium, and sodium disposed between the positive electrode part and the negative electrode part. A solid electrolyte having ion conductivity and sodium having a sodium pore;
In a sodium sampling device for collecting sodium into a safety tube for a sulfur battery, the safety tube includes a sodium storage portion and a sodium injection tube, and the flow hole is provided with a plug of a temperature fuse that melts at an operating temperature of the sodium / sulfur battery. A sodium sampling port connected to the end of the injection pipe, wherein the sampling port is provided with a decompression device for reducing the pressure in the sodium storage section through the collection port, and collecting the sodium in the depressurized sodium storage section. And a sodium tank for storing sodium. 12. The sodium sampling apparatus according to claim 11, wherein said safety tube comprises a sodium storage portion and a sodium injection tube having a stress relaxation mechanism, and said negative electrode is provided at said injection tube portion on an end side of said stress relaxation mechanism. A switching valve for switching a 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 collection device, comprising a sealing device for sealing the sodium.