JPH10199566A - Positive electrode vessel for sodium-sulfur battery, and sodium-sulfur battery using the vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent causing damage to the various joints and members of a sodium-sulfur battery, and the tube bottom of a solid electrolyte tube, by providing a construction, having given deforming strength, on a positive electrode vessel. SOLUTION: In this positive electrode vessel 6 for a sodium-sulfur battery, deforming strength; in the axial direction of the constriction 10 of the positive electrode vessel 6 to force generated by the vessel 6 and a solid electrolyte tube 2 due to the terminal expansion difference between the vessel 6 and the tube 2 from the solidification temperature of sodium polysulfide to room temperature; is set so as to be less than the tube bottom strength of the tube 2. This can prevent damage to the tube bottom of the tube 2 because a load; applied to the tube bottom of the tube 2 due to the solidification of the sodium polysulfide and sulfur at the time of the lowering of battery temperature, and the thermal contraction difference between the tube 2 and the vessel 6; preferentially deforms the constriction 10 provided on the vessel 6.

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 an anode container containing sulfur as an anode active material or a conductive material impregnated with the same, and a sodium-sulfur battery using the same.

[0002]

2. Description of the Related Art A sodium-sulfur battery is a beta-alumina solid having sodium, which is a cathode active material, and sulfur, which is an anode active material, on one side, and both having selective permeability to sodium ions. Isolate with electrolyte, 30
It is a high temperature secondary battery operated at 0 to 350 ° C.

A configuration of such a sodium-sulfur battery is, as shown in FIG. 1, for example, a bottomed cylindrical anode container for accommodating an anode conductive material 11 such as carbon felt impregnated with sulfur as an anode active material. 6 and a bottomed cylindrical solid electrolyte tube (beta-alumina tube) 2 having a function of storing sodium 12 and selectively transmitting sodium ions. In some cases, a sodium protection tube is interposed between the sodium 12 and the solid electrolyte tube 2. The anode container 6 includes a cylindrical body 13 and an anode container lid 8.
The solid electrolyte tube 2 includes an upper end portion of the cylindrical body 13, an insulator ring 1 made of, for example, alpha alumina, and a ring-shaped bottom portion 18.
And a cylindrical metal fitting 7 having a flange 19.

[0004] This joining state will be described in more detail.
As shown in FIG. 2A, the insulator ring 1 is inserted into a cylinder of a cylindrical metal fitting 7 having a ring-shaped bottom portion 18 and a flange 19, and is thermally and pressure-bonded at the bottom portion by a bonding agent 14, and the inside of the ring. The peripheral surface is joined to the upper end of the solid electrolyte tube 2 by the joining glass 15, and the lower surface of the flange 19 of the cylindrical metal fitting 7 and the upper end of the anode container 6 are welded.

[0005] In the sodium-sulfur battery 17 having the above configuration, at the time of discharge, the sodium 12 emits electrons to become sodium ions.
It passes through the inside and moves to the anode side, reacts with the sulfur in the anode conductive material 11 and the electrons passed through the external circuit to generate sodium polysulfide, and generates a voltage of about 2V. On the other hand, at the time of charging, a reaction of producing sodium and sulfur occurs in reverse to the discharging.

Incidentally, the sodium-sulfur battery 17
There is a temperature difference between when the battery is operating and when the battery is stopped, and when the temperature drops when the battery is stopped, sodium polysulfide or sulfur solidifies, and the solid electrolyte tube 2 and the anode container 6 are mutually restrained. When the temperature of the battery is lowered, both the solid electrolyte tube 2 and the anode container 6 thermally contract, but the metal anode container 6
The thermal contraction of the anode container 6 is large, and the contraction of the anode container 6 is suppressed by the solid electrolyte tube 2 having a small thermal contraction.
A downward load acts on the joint 4 between the insulator ring 1 and the cylindrical metal fitting 7 that connects the anode container 6 and the anode ring 6 (FIG. 2).
(A direction of the arrow). In addition, a load is also applied to the joint 3 between the insulator ring 1 and the solid electrolyte tube 2, the weld 5 between the cylindrical metal fitting 7 and the anode container 6, and the weld 9 between the cylindrical body 13 and the anode container lid 8. In some cases, these joints were broken.
Further, the insulator ring 1 itself may be broken, or the cylindrical metal fitting 7 may be bent by a load.
As shown in (b), since the heat shrinkage of the anode container 6 is larger than the heat shrinkage of the solid electrolyte tube 2, the sulfur or sodium polysulfide 20 at the tube bottom of the solid electrolyte tube 2 and near the tube bottom is reduced.
Pressed against the bottom of the solid electrolyte tube 2, the solid electrolyte tube 2
In some cases, the bottom of the tube was damaged.

Therefore, conventionally, in order to prevent the above-mentioned breakage due to solidification of sodium polysulfide or sulfur and a difference in heat shrinkage between the solid electrolyte tube 2 and the anode container 6, the anode container 6
Some measures have been taken, such as forming a constriction 10 in a part of the part to provide a spring effect to reduce the load.

[0008]

However, even when the above-described countermeasures are taken, the above-described joint,
When the welded portion and the bottom of the solid electrolyte tube 2 were weak in strength, breakage sometimes occurred.

[0009]

Means for Solving the Problems The present invention has been made in view of such a situation, and an object of the present invention is to improve the strength reliability of a sodium-sulfur battery when the battery temperature drops. Solidification of sodium polysulfide and sulfur,
Another object of the present invention is to provide an anode container capable of absorbing a load caused by a difference in thermal contraction between the solid electrolyte tube and the anode container.

That is, according to the present invention, in a sodium-sulfur battery in which sodium is provided as a cathode active material inside a bottomed solid electrolyte tube and sulfur is provided as an anode active material outside the solid electrolyte tube, It is a bottomed cylindrical anode container that is joined via an insulator ring and a cylindrical fitting to which a tube is inserted and joined, and contains molten sulfur, and has a neck that expands and contracts in the axial direction around it. The deformation strength in the axial direction of the constriction against the force generated between the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature to room temperature is from room temperature to the sodium-sulfur battery. In the temperature range up to the maximum temperature at the time of use of the present invention, an anode container having a smaller tube bottom strength of the solid electrolyte tube is provided.

In the above-mentioned anode container, the deformation strength of the above-mentioned constriction in the axial direction is as follows:
It is preferable that the value be smaller than 3/5 of the tube bottom strength of the solid electrolyte tube, or a value such that the destruction rate obtained from the Weibull distribution of the tube bottom strength of the solid electrolyte tube is 1 × 10 ⁻⁴ or less.

In the anode container, the deformation strength of the constriction in the axial direction is preferably smaller than the tube bottom strength of the solid electrolyte tube in a temperature range from room temperature to the solidification temperature of sodium polysulfide. The fracture rate determined from the tube bottom strength of the electrolyte tube being less than 3/5 or the Weibull distribution of the tube bottom strength of the solid electrolyte tube is 1 ×
The value is more preferably 10 ^-4 or less.

Further, according to the present invention, a sodium-sulfur battery in which molten metal sodium is disposed as a cathode active material inside a bottomed solid electrolyte tube, and molten sulfur is disposed as an anode active material outside the solid electrolyte tube. , A bottomed cylindrical anode container which is joined via a cylindrical fitting to an insulator ring into which the solid electrolyte tube is inserted and joined, and contains molten sulfur, and has a constriction around its periphery that expands and contracts in the axial direction. The deformation strength in the axial direction of the constriction against the force generated between the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature, In the temperature range from room temperature to the maximum temperature during use of the sodium-sulfur battery, the tensile strength of the insulator ring in the axial direction, and the axial tensile strength of the joint between the insulator ring and the cylindrical metal fittings. Tensile strength, axial tensile strength of joint between insulator ring and solid electrolyte tube, buckling strength of cylindrical fitting, tensile strength of anode vessel itself, strength of welded part between anode vessel and cylindrical fitting, solid electrolyte An anode container is provided that is smaller than the minimum tube bottom strength.

In the above anode container, it is preferable that the deformation strength in the axial direction of the constriction satisfies the above condition in a temperature range from room temperature to the solidification point of sodium polysulfide.

The anode container may be formed by welding an anode container lid to one end of a cylindrical body. In this case, the anode container and the solid are cooled from the solidification temperature of sodium polysulfide to room temperature. The deformation strength in the axial direction of the constriction with respect to the force generated between the anode container and the solid electrolyte tube due to the difference between the thermal expansion of the electrolyte tube and the solid electrolyte tube is greater than the welding strength between the cylindrical body and the anode container lid in the above temperature range. It is necessary to be smaller than the strength of the part.

Further, in the above-mentioned anode container, the deformation strength in the axial direction of the above-mentioned constriction is such that, in a temperature range from room temperature to the maximum temperature when the sodium-sulfur battery is used, the tensile strength of the insulator ring in the axial direction is obtained. Axial tensile strength of the joint between the insulator ring and the cylindrical metal fitting, axial tensile strength of the joint between the insulator ring and the solid electrolyte tube, buckling strength of the cylindrical metal fitting, tensile strength of the anode container itself, It is preferable that the strength of the welded portion between the anode container and the cylindrical metal fitting and the bottom strength of the solid electrolyte tube be smaller than 2/3 of the minimum strength.

In this case, in the temperature range from room temperature to the freezing point of sodium polysulfide, the difference between the thermal expansion of the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature results in the difference between the anode container and the solid electrolyte tube. It is preferable that the deformation strength in the axial direction of the constriction with respect to the force generated with the tube satisfies the above condition.

Further, when the anode container is formed by welding the lid of the anode container to one end of the cylindrical body, the deformation strength in the axial direction of the constriction and the strength of the welded portion between the cylindrical body and the lid of the anode container are also two. It is preferably smaller than / 3.

Further, in the above-mentioned anode container, the insulator ring and the cylindrical metal fitting have a deformation strength in the axial direction of the above-mentioned constriction in a temperature range from room temperature to a maximum temperature when the sodium-sulfur battery is used. It is preferable that the fracture rate of the tensile strength in the axial direction of the joint portion obtained from the Weibull distribution be a value of 1 × 10 ⁻⁴ or less.

It is preferable that the deformation strength in the axial direction of the constriction satisfies the above condition in a temperature range from room temperature to the freezing point of sodium polysulfide.

Further, according to the present invention, molten metal sodium is disposed as a cathode active material inside a bottomed solid electrolyte tube, and molten sulfur is disposed as an anode active material outside the solid electrolyte tube. Is a sodium-sulfur battery joined via a cylindrical metal fitting to an insulator ring into which a solid electrolyte tube is inserted and joined, and a sodium-sulfur battery using the above-described anode container is provided. .

In the above sodium-sulfur battery,
The anode container and the cylindrical fitting are made of aluminum or an aluminum alloy, the solid electrolyte tube is made of β-alumina,
Preferably, the insulator ring comprises alpha alumina.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the force generated by the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature, The deformation strength in the axial direction of the neck of the anode container is set to be smaller than the tube bottom strength of the solid electrolyte tube. By doing so, the load applied to the bottom of the solid electrolyte tube due to the solidification of sodium polysulfide and sulfur at the time of battery temperature drop and the difference in thermal contraction between the solid electrolyte tube and the anode container causes the constriction provided in the anode container to decrease. Since the tube is preferentially deformed, damage to the bottom of the solid electrolyte tube can be prevented.

The deformation strength in the axial direction of the constriction is determined from the fact that the tube bottom strength of the solid electrolyte tube is smaller than 3/5 or the Weibull distribution of the tube bottom strength of the solid electrolyte tube in the above temperature range. It is preferable that the destruction rate is a value that is 1 × 10 ⁻⁴ or less, more preferably 1 × 10 ⁻⁵ or less.

When the temperature of the sodium-sulfur battery is lowered for inspection or the like, the effect of solidification of sodium polysulfide starts to appear from around 200 ° C. Also, at the time of inspection,
The sodium-sulfur battery is finally cooled to room temperature.
Therefore, it is preferable that the above relationship be satisfied at least in a temperature range from 15 ° C., which is room temperature, to 200 ° C., at which solidification of sodium polysulfide starts. However, more preferably, the operating temperature of the sodium-sulfur battery is 300 to
Temperature range covering 350 ° C, that is, from 15 ° C to 350 ° C
It is desirable that the above relationship be satisfied in a temperature range up to ° C.

Further, in the present invention, the anode container is provided with respect to the force generated between the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature. The deformation strength in the axial direction of the constriction is the axial tensile strength of the insulator ring, the axial tensile strength of the joint between the insulator ring and the cylindrical fitting,
Axial tensile strength of joint between insulator ring and solid electrolyte tube, buckling strength of cylindrical fitting, tensile strength of anode container itself, strength of weld between anode container and cylindrical fitting, solid electrolyte tube tube It is set to be smaller than the minimum one of the bottom strengths. Further, it is preferable that it is smaller than 2/3 of the smallest of these, more preferably smaller than 1/2. By doing so, the solidification of sodium polysulfide and sulfur when the battery temperature drops, and the load caused by the difference in heat shrinkage of the solid electrolyte tube and the anode container preferentially deforms the neck provided in the anode container. Can be reduced. Among the above-mentioned joints, members, and the like, the joint between the insulator ring and the cylindrical fitting is the weakest, and is frequently damaged. Therefore, the minimum load required to deform the constriction is generally determined based on the axial tensile strength of the joint.

When the anode container is formed by welding the cylindrical body and the anode container lid, the deformation strength of the constriction is
It is necessary to make the strength smaller than the strength of the weld.
This is because a load is also applied to the welded portion between the cylindrical body and the anode container lid.

Axial deformation of the neck of the anode container with respect to the force generated between the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature As for the strength, the breaking rate of the tensile strength in the axial direction of the joint between the insulator ring and the cylindrical metal fitting, which is determined from the Weibull distribution, is 1 × 10 ^−4.
It is preferable that the value be as follows, but 1 × 10
^The value is more preferably ^-6 or less.

For the same reason as described above, the above-mentioned relationship is preferably satisfied at least in a temperature range from room temperature of 15 ° C. to 200 ° C. at which solidification of sodium polysulfide starts. However, more preferably, sodium-
It is desirable that the above relationship be satisfied in a temperature range covering the operating temperature of the sulfur battery of 300 to 350 ° C., that is, a temperature range of 15 ° C. to 350 ° C.

The strength of the neck of the anode container is adjusted by selecting a material, changing the thickness of the anode container, changing the shape of the neck, and the like. As the material of the anode container, it is preferable to use aluminum or an aluminum alloy because it is lightweight and inexpensive, but in particular, Al-Mn or Al-M
It is preferable to use a g-based alloy. Specifically, Al
A3003 or A3004 as the Mn system, Al-M
It is preferable to use A5052 as the g-system.

When a sodium-sulfur battery is manufactured using the above-described anode container, β-alumina is preferably used for the solid electrolyte tube. It is preferable to use α-alumina as the insulator ring. Although it is preferable to use the same material as the anode container as the cylindrical metal fitting, it is particularly preferable to use an aluminum alloy.

[0032]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Examples 1 to 4) The deformation strength in the axial direction of the constriction provided in the anode container was changed from room temperature to sodium-
In the temperature range up to the maximum temperature when using a sulfur battery,
A sodium-sulfur battery was manufactured using an anode container set so as to be smaller than the tube bottom strength of the solid electrolyte tube, and the occurrence of breakage at the tube bottom of the solid electrolyte tube was examined by performing a temperature rise / fall test. The solid electrolyte tube has an outer diameter of 45m
m, the thickness of the cylindrical part is 1.6 mm, and the thickness of the tube bottom is 1.6 m
m, and a tube bottom having a hemispherical shape was used. The bottom strength of the tube is 9.8 kN (1000 kg).
The value of 5 was 5.9 kN. Further, the destruction rate determined from the Weibull distribution of the tube bottom strength of the solid electrolyte tube is 1 × 10 ^−4.
Was 6.5 kN. In Table 1,
The values obtained by applying various loads to the produced sodium-sulfur battery and calculating the estimated fracture rate of the tube bottom of the solid electrolyte tube for each load are shown. In addition, as shown in FIG. 3, the tube bottom strength is measured by applying a downward load to the tube bottom of the solid electrolyte tube 2 with the opening portion downward by a strength measuring jig 16 to perform a destructive test. Was measured. The estimated fracture rate of the tube bottom was obtained from a Weibull curve created based on the measured value of the tube bottom strength.

[0034]

[Table 1]

In Examples 1, 2, and 3, the deformation strength of the neck was 8.8 kN (900 kg), respectively.
7.4 kN (750 kg) and 6.9 kN (700 kN)
g). In Example 4, 5.9 kN (50 kN
0 kg), that is, a value smaller than the value at which the fracture rate of the tube bottom strength becomes 1 × 10 ⁻⁴ . In addition, the tensile strength of the neck was used as the deformation strength of the neck. The measurement of the deformation strength of the constriction was performed as follows. First, as shown in FIG. 4A, a constriction 10 is formed in a pipe 21 made of the same material as the anode container, and a tensile load is applied to the pipe 21 in the vertical direction, as shown in FIG. The relationship between the load and the magnitude of the displacement caused by the constriction was plotted on a graph. next,
Find the load corresponding to the load measurement displacement from the above graph,
The value was defined as the constriction deformation strength. The magnitude of the displacement was determined by measuring the length of the neck 22 with a displacement meter.

The temperature rise / fall test was 1000 for each example.
Battery, and raise and lower the temperature from room temperature to
After repeating this process, the number of solid electrolyte tubes having a broken tube bottom was checked. In addition, charging and discharging of the sodium-sulfur battery were performed at the first temperature rise.

Table 2 shows the number of solid electrolyte tubes whose tube bottom was damaged by the temperature rise test.

(Comparative Example 1) The deformation strength of the neck is 9.8 kN (1000) which is the same value as the tube bottom strength of the solid electrolyte tube.
(kg) except that the solid electrolyte tube was the same as in Examples 1 to 4, and a temperature rise / fall test was performed under the same conditions as in Examples 1 to 4. Was investigated. Table 2 shows the number of solid electrolyte tubes having a broken tube bottom.

[0039]

[Table 2]

(Examples 5 to 7) The deformation strength in the axial direction of the constriction provided in the anode container was changed from room temperature to sodium-
In the temperature range up to the maximum temperature when using a sulfur battery,
A sodium-sulfur battery was manufactured using an anode container set so as to be smaller than the tube bottom strength of the solid electrolyte tube, and the occurrence of breakage at the tube bottom of the solid electrolyte tube was examined by performing a temperature rise / fall test. The solid electrolyte tube has an outer diameter of 45m
m, the thickness of the cylindrical part is 1.6 mm, and the thickness of the tube bottom is 1.6 m
m, and the shape of the tube bottom is a 1/4 sphere, that is, when the sphere is cut at a plane oriented at right angles to an arbitrary center line and passing through a point 1/4 from the end of the center line. A tube having a tube bottom having a shape corresponding to the curved surface of the smaller piece was used. The tube bottom strength is 7.9kN (810kg),
The value of 3/5 was 4.7 kN. In addition, the destruction rate obtained from the Weibull distribution of the tube bottom strength of the solid electrolyte tube is 1%.
The value of the load to be × 10 ^-4 was 4.8 kN. In addition,
Table 3 shows values obtained by applying loads of various sizes to the produced sodium-sulfur batteries and estimating a fracture rate of the bottom of the solid electrolyte tube for each load.

[0041]

[Table 3]

The deformation strength of the neck was 7.4 kN (750 kg) and 5.9 kN, respectively, in order from Example 5.
(600 kg) and 4.9 kN (500 kg).
The temperature rise / fall test was performed under the same conditions as in Examples 1 to 4.

Table 4 shows the number of solid electrolyte tubes whose tube bottom was damaged by the temperature rise test.

(Comparative Example 2) The deformation strength of the neck is 8.8 kN (900 kg), which is larger than the tube bottom strength of the solid electrolyte tube.
Using the same solid electrolyte tubes as in Examples 5 to 7 and performing a temperature rise / fall test under the same conditions as in Examples 5 to 7, the occurrence of breakage at the tube bottom of the solid electrolyte tubes Was examined. Table 4 shows the number of solid electrolyte tubes with broken bottoms.
Shown in

[0045]

[Table 4]

(Examples 8 to 11) The deformation strength in the axial direction of the constriction provided in the anode container is from the room temperature to the maximum temperature when the sodium-sulfur battery is used. Making a sodium-sulfur battery using an anode container set to be smaller,
The occurrence of breakage at the bottom of the solid electrolyte tube was examined by performing a temperature rise / fall test. The solid electrolyte tube has an outer diameter of 45
mm, the thickness of the cylindrical portion is 1.6 mm, and the thickness of the tube bottom is 3.0.
mm and the shape of the tube bottom was a 1/4 sphere.
Also, the tube bottom strength is 12.3 kN (1250 kg),
The value of 3/5 was 7.4 kN. In addition, the destruction rate obtained from the Weibull distribution of the tube bottom strength of the solid electrolyte tube is 1%.
The value of the load to be × 10 ^-4 was 8.0 kN. In addition,
Table 5 shows values obtained by applying loads of various magnitudes to the produced sodium-sulfur batteries and estimating the fracture rate of the bottom of the solid electrolyte tube for each load.

[0047]

[Table 5]

In Examples 8, 9 and 10, the deformation strength of the neck was 10.8 kN (1100 kN), respectively.
g), 9.8 kN (1000 kg) and 8.8 kN (9
00 kg). In the eleventh embodiment, 7.4 k
N (750 kg), that is, the failure rate of the tube bottom strength is 1 × 1
The value was set to a value smaller than the value of the load to be 0 ^-4 . The temperature rise / fall test was performed under the same conditions as in Examples 1 to 4.

Table 6 shows the number of solid electrolyte tubes whose tube bottom was damaged by the temperature rise test.

(Comparative Example 3) The deformation strength of the neck is 12.3 kN (125) which is the same value as the bottom strength of the solid electrolyte tube.
0 kg), using the same solid electrolyte tube as in Examples 8 to 11, and performing a temperature rise / fall test under the same conditions as in Examples 8 to 11, to thereby damage the solid electrolyte tube at the bottom of the tube. Was investigated. Table 6 shows the number of solid electrolyte tubes in which the tube bottom was damaged.

[0051]

[Table 6]

By making the deformation strength of the neck smaller than the tube bottom strength of the solid electrolyte tube, the damage of the tube bottom of the solid electrolyte tube can be reduced compared to the case where the deformation strength of the neck is made equal to or more than the tube bottom strength of the solid electrolyte tube. Was reduced to 1/10 or less. In addition, the deformation strength of the constriction is determined by determining that the destruction rate obtained from the Weibull distribution of the bottom strength of the solid electrolyte tube is 1 × 10 ^-4
When the load value was smaller than the load value, the frequency of breakage of the tube bottom could be suppressed to less than 10 ^-3 .

Example 12 By applying loads of various magnitudes to the manufactured sodium-sulfur battery, the estimated destruction rate of the joint (hereinafter, TCB joint) between the insulator ring and the cylindrical metal fitting was reduced. It was determined for each load. Based on the results, an anode container was prepared in which the load required to deform the constricted portion was appropriately adjusted, and a sodium-sulfur battery was manufactured using the anode container.

Table 7 shows that the material strength was 350MP each.
5 shows the results of measuring the estimated failure rates of the TCB joints with respect to loads of various magnitudes using two types of insulator rings, a and 490 MPa. The estimated destruction rate was determined as follows. First, as shown in FIG. 5, a cylindrical metal fitting 7 is joined to the outer periphery of the insulator ring 1, and a strength measuring jig 1 is provided above the cylindrical metal fitting 7 and below the insulator ring 1.
6 by applying a load in the direction of the arrow.
The breaking strength of the B joint was measured. The estimated fracture rate of the TCB joint was determined from a Weibull curve created based on the measured values of the fracture strength.

[0055]

[Table 7]

It is desirable to set the deformation load of the constricted part of the anode container on the basis of the fracture load corresponding to the smaller estimated failure rate. However, if the deformation load of the constricted portion is set too small, the mechanical strength of the constricted portion itself is reduced, which adversely affects the durability of the battery.

From the results in Table 7, for example, the estimated destruction rate is 1
If you want to 0 ^-5 or less, it can be seen that it is preferable to use an insulator ring of 490 MPa. The anode container was manufactured based on the measurement results in Table 7, and a sodium-sulfur battery was manufactured using the anode container. As a result, breakage of the TCB junction and the like could be prevented, and good results could be obtained. .

[0058]

Effect of the Invention The anode container for a sodium-sulfur battery of the present invention has a neck having a predetermined deformation strength,
When the temperature of the battery drops, it effectively absorbs the strain caused by the solidification of sodium polysulfide and the difference in thermal expansion between the anode container and the solid electrolyte tube, and various junctions and members of the sodium-sulfur battery and the solid electrolyte tube This can prevent the bottom of the tube from being damaged. Therefore, the durability of the sodium-sulfur battery can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a sodium-sulfur battery.

FIG. 2 (a) is a schematic view showing a connection state between a solid electrolyte tube and a tubular body. (B) It is explanatory drawing which shows the load applied to the tube bottom of a solid electrolyte tube.

FIG. 3 is a schematic diagram showing a method for measuring the tube bottom strength of a solid electrolyte tube.

4A is a schematic diagram illustrating a method for measuring the deformation strength of a neck, and FIG. 4B is an example of a graph illustrating a relationship between a load and a magnitude of a displacement caused by the neck.

FIG. 5 is a schematic view showing a method for measuring the breaking strength of a TCB joint.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Insulator ring, 2 ... Solid electrolyte tube, 3 ... Joint part between insulator ring and solid electrolyte pipe, 4 ... Joint part between insulator ring and cylindrical metal fitting, 5 ... ..Welded portion between cylindrical fitting and anode container, 6 ... Anode container, 7 ... Cylindrical fitting, 8 ...
Anode container lid, 9 ... Welded part between cylindrical body and anode container lid, 1
0: constriction, 11: conductive material for anode, 12: molten metal sodium, 13: tubular body, 14: bonding agent, 15 ...
Bonding glass, 16: strength measuring jig, 17: sodium-sulfur battery, 18: ring-shaped bottom, 19: flange,
20: sulfur or sodium polysulfide, 21: pipe, 2
2. The length of the constriction.

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Satoshi Kitagawa 2-56, Suda-cho, Mizuho-ku, Nagoya-shi, Aichi Japan Insulator Co., Ltd.

Claims (16)

[Claims] 1. A sodium-sulfur battery in which sodium is arranged as a cathode active material inside a bottomed solid electrolyte tube and sulfur is arranged outside the solid electrolyte tube as an anode active material. A cylindrical anode container with a bottom that is joined to the insulator ring that has been made through the cylindrical fitting and that contains the molten sulfur, has a neck that expands and contracts in the axial direction around it, and The deformation strength in the axial direction of the constriction against the force generated between the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube up to room temperature is from room temperature to the use of the sodium-sulfur battery. An anode container characterized by having a lower tube bottom strength of the solid electrolyte tube in a temperature range up to the maximum temperature at the time of (1). 2. The deformation of the constriction in the axial direction with respect to the force generated between the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature. The strength is lower than the tube bottom strength of the solid electrolyte tube in a temperature range from room temperature to a solidification temperature of sodium polysulfide.
The anode container according to item 1. 3. The deformation of the constriction in the axial direction with respect to the force generated between the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature. The anode container according to claim 1, wherein the strength is less than 3/5 of the tube bottom strength of the solid electrolyte tube in a temperature range from room temperature to a maximum temperature when the sodium-sulfur battery is used. 4. The deformation of the constriction in the axial direction with respect to the force generated between the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature. The anode container according to claim 2, wherein the strength is less than 3/5 of the tube bottom strength of the solid electrolyte tube in a temperature range from room temperature to a solidification temperature of sodium polysulfide. 5. The deformation of the constriction in the axial direction with respect to the force generated between the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature. Strength, in a temperature range from room temperature to the maximum temperature when the sodium-sulfur battery is used, a value at which the destruction rate obtained from the Weibull distribution of the tube bottom strength of the solid electrolyte tube is 1 × 10 ⁻⁴ or less. The anode container according to claim 1, which is: 6. The deformation of the constriction in the axial direction with respect to the force generated between the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature. The strength is such that in a temperature range from room temperature to the solidification temperature of sodium polysulfide, the destruction rate obtained from the Weibull distribution of the tube bottom strength of the solid electrolyte tube is a value that is 1 × 10 ⁻⁴ or less. Anode container as described. 7. A sodium-sulfur battery in which sodium is disposed as a cathode active material inside a bottomed solid electrolyte tube, and sulfur is disposed outside the solid electrolyte tube, and the solid electrolyte tube is inserted and joined. A cylindrical anode container with a bottom that is joined to the insulator ring that has been made through the cylindrical fitting and that contains the molten sulfur, has a neck that expands and contracts in the axial direction around it, and The deformation strength in the axial direction of the constriction against the force generated between the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube up to room temperature is from room temperature to the use of the sodium-sulfur battery. In the temperature range up to the maximum temperature at the time of the above, the axial tensile strength of the insulator ring, the axial tensile strength of the joint between the insulator ring and the cylindrical metal fitting, the insulation The axial tensile strength of the joint between the body ring and the solid electrolyte tube, the buckling strength of the cylindrical fitting, the tensile strength of the anode container itself, the strength of the weld between the anode container and the cylindrical fitting, and An anode container characterized by being smaller than the minimum tube bottom strength of the solid electrolyte tube. 8. The deformation of the constriction in the axial direction with respect to the force generated between the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature. In the temperature range from room temperature to the solidification temperature of sodium polysulfide, the tensile strength of the insulator ring in the axial direction, the tensile strength of the joint between the insulator ring and the cylindrical metal fitting, the tensile strength of the insulator ring, Axial tensile strength of the joint with the solid electrolyte tube, buckling strength of the cylindrical fitting, tensile strength of the anode container itself, strength of a weld between the anode container and the cylindrical fitting, and the solid electrolyte The anode container according to claim 7, wherein the tube bottom strength of the tube is smaller than the minimum one. 9. An anode container lid is welded to one end of a cylindrical body, and the anode container and the solid electrolyte are caused by a difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature. The anode container according to claim 7 or 8, wherein the deformation strength in the axial direction of the constriction with respect to the force generated by the tube is smaller than the strength of the welded portion between the cylindrical body and the anode container lid in the temperature range. . 10. The deformation of the constriction in the axial direction with respect to the force generated between the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature. In the temperature range from room temperature to the maximum temperature when the sodium-sulfur battery is used, the tensile strength of the insulator ring in the axial direction, the tensile strength of the joint between the insulator ring and the cylindrical fitting in the axial direction The axial tensile strength of the joint between the insulator ring and the solid electrolyte tube, the buckling strength of the cylindrical fitting, the tensile strength of the anode vessel itself, and the strength of the weld between the anode vessel and the cylindrical fitting. 2 of the smallest of the strength and the bottom strength of the solid electrolyte tube.
The anode container according to claim 7, which is smaller than / 3. 11. The deformation of the constriction in the axial direction with respect to the force generated between the anode container and the solid electrolyte tube due to the difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature. In the temperature range from room temperature to the freezing point of sodium polysulfide, the tensile strength of the insulator ring in the axial direction, the tensile strength of the joint between the insulator ring and the cylindrical metal fitting, the strength of the insulator ring and the Axial tensile strength of the joint with the solid electrolyte tube, buckling strength of the cylindrical metal fitting, tensile strength of the anode container itself, strength of a weld between the anode container and the cylindrical metal fitting, and the solid electrolyte tube 2 of the smallest tube bottom strengths
The anode container according to claim 8, which is smaller than / 3. 12. An anode container lid is formed by welding an anode container lid to one end of a cylindrical body. The anode container and the solid electrolyte are caused by a difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature. The deformation strength in the axial direction of the constriction with respect to the force generated by the tube is 2% of the strength of the welded portion between the cylindrical body and the anode container lid in the temperature range.
The anode container according to claim 10 or 11, which is smaller than / 3. 13. An axial deformation of the constriction due to a force generated between the anode container and the solid electrolyte tube due to a difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature. In the temperature range from room temperature to the maximum temperature when the sodium-sulfur battery is used, the fracture rate obtained from the Weibull distribution of the tensile strength in the axial direction of the joint between the insulator ring and the cylindrical metal fitting. Is a value that is 1 × 10 ⁻⁴ or less. 14. An axial deformation of the constriction due to a force generated between the anode container and the solid electrolyte tube due to a difference in thermal expansion between the anode container and the solid electrolyte tube from the solidification temperature of sodium polysulfide to room temperature. In the temperature range from room temperature to the solidification point of sodium polysulfide, the fracture rate of the tensile strength in the axial direction of the joint between the insulator ring and the cylindrical metal fitting, which is obtained from the Weibull distribution, is 1 × 10 ^−4. The anode container according to claim 8, which has the following values. 15. An anode vessel containing sodium as a cathode active material inside a bottomed solid electrolyte tube, sulfur as an anode active material outside the solid electrolyte tube, and an anode container containing the sulfur, A sodium-sulfur battery joined via an insulator ring and a cylindrical fitting to which an electrolyte tube is inserted and joined, wherein the anode container according to any one of claims 1 to 14 is used. Sodium-sulfur battery. 16. The sodium-sulfur battery according to claim 15, wherein the anode container and the cylindrical metal fitting are made of aluminum or an aluminum alloy, the solid electrolyte tube is made of β-alumina, and the insulator ring is made of α-alumina. .