JPH06196204A - Junction structure between solid electrolytic tube and insulating ring in sodium-sulfur battery and sodium-sulfur battery - Google Patents

Abstract

PURPOSE:To secure the bonding strength, improve the bonding reliability against the thermal stress and mechanical stress, facilitate manufacture, and improve the safety of a battery. CONSTITUTION:An insulating ring 4 is bonded at the end section of a cylindrical positive electrode container. The opening end section of a bottomed cylindrical solid electrolyte tube 5 is arranged on the inner periphery of the insulating ring 4, and the insulating ring 4 and the solid electrolyte tube 5 are bonded via glass 24. A hook section 14 serving as the L-shaped first opposite face proximately facing the outer periphery 5b of the opening end section of the solid electrode tube 5 and the opening end face 5a and a glass filling notch 20 serving as the second opposite face facing the outer periphery 5b of the opening end section at an interval wider than the interval between the hook section 14 and the solid electrolyte tube 5 are formed on the inner periphery of the insulating ring 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint structure between a solid electrolyte tube and an insulating ring in a sodium-sulfur battery.

[0002]

2. Description of the Related Art Heretofore, in joining a solid electrolyte tube made of β-alumina and an insulating ring made of α-alumina, a joining structure in which glass is interposed is known. For example, the present inventors have previously proposed that at least one of the solid electrolyte tube and the insulating ring is provided with a tapered portion for forming a glass reservoir (Japanese Patent Laid-Open No. 3-291860). The shape of the tapered portion, the surface condition, and the like reduce the stress remaining in the glass solder in the glass pool, thereby suppressing the occurrence of cracks in the glass bonding portion.

[0003]

The sodium-sulfur battery is a high-temperature battery that operates at 300 to 350 ° C., and its temperature changes greatly due to repeated operation and shutdown, and sodium, which is an active material as the battery operates. Ions move through the solid electrolyte tube, and the active material capacity inside the solid electrolyte tube increases or decreases. Then, with respect to the glass bonding portion,
Expansion of the solid electrolyte tube or insulating ring due to the temperature change,
Thermal stress due to difference in contraction and mechanical stress due to external force are likely to be applied. Therefore, there is a possibility that cracks may occur in the glass joint portion or the glass joint portion may be damaged.

However, in the above-mentioned conventional joining structure, since the glass reservoir is simply provided by the tapered portion, the mechanical strength of the joining portion varies widely. Therefore, there is a problem in that the reliability of joining with respect to thermal stress and mechanical stress is insufficient.

Further, in the conventional joining structure, the solid electrolyte tube is only joined to the insulating ring on the outer peripheral surface thereof. For this reason, the positional relationship between the two tends to shift in the axial direction of the insulating ring, and a jig has been forced to be used so that this shift does not occur during manufacturing. Therefore,
The conventional joining structure also has a problem that the manufacturing is troublesome.

Moreover, the solid electrolyte tube may be broken in an abnormal state, but if the broken part occurs at the joint between the solid electrolyte tube and the insulating ring, sodium in the solid electrolyte tube leaks out, causing ignition, etc. There was a problem that there was a danger of.

The present invention has been made in view of the above conventional problems. The first purpose thereof is to secure a bonding strength, have a high reliability of bonding against thermal stress and mechanical stress, and easily manufacture a solid electrolyte tube and an insulating ring in a sodium-sulfur battery. It is to provide a sodium-sulfur battery. A second object is to provide a sodium-sulfur battery capable of specifying the breakage position of the solid electrolyte tube at the time of abnormality to prevent sodium from leaking and improving safety.

[0008]

In order to achieve the above-mentioned first object, in the invention according to claim 1, an insulating ring is joined to the end of a cylindrical anode container and the inner circumference of this insulating ring is joined. Bonding of solid electrolyte tube and insulating ring in sodium-sulfur battery in which the open end of a solid electrolyte tube having a bottomed cylindrical shape is arranged on the surface and the insulating ring and solid electrolyte tube are bonded via glass In the structure, on the inner peripheral surface of the insulating ring, an L-shaped first opposing surface that closely opposes the outer peripheral surface of the opening end portion of the solid electrolyte tube and the opening end surface, and the first opposing surface are provided. It is characterized in that a second facing surface facing the outer peripheral surface of the opening end portion is formed with a spacing wider than the spacing with the solid electrolyte tube.

According to a second aspect of the invention, in the first aspect of the invention, a chamfered portion is provided on the outer peripheral edge of the solid electrolyte tube, and a corner portion of the first facing surface facing the chamfered portion is formed. It is characterized by having an arc surface. Furthermore, in order to achieve the first object, in the invention of the sodium-sulfur battery according to claim 3, an insulating ring is joined to the end of the cylindrical anode container, and the inner peripheral surface of this insulating ring is joined. The open end portion of the solid electrolyte tube having a bottomed cylindrical shape is arranged, and the insulating ring and the solid electrolyte tube are joined together via glass, and the anode conductive material is connected between the anode container and the solid electrolyte tube. Sodium containing a mat, impregnated with sulfur in the mat, and containing sodium in the solid electrolyte tube.
In the sulfur battery, the wall thickness at the open end of the solid electrolyte tube is thicker than the wall thickness at the current-carrying part of the battery.

In order to achieve the first and second objects, according to the invention of claim 4, in the invention of claim 3, the open end of the solid electrolyte tube and the current-carrying part are provided with a predetermined inclined surface. And the end of the inclined surface on the side of the current-carrying part is set at the position where the mat of the conductive material for the anode exists.

[0011]

The open end of the solid electrolyte tube is supported by the L-shaped first facing surface of the insulating ring. Therefore, the solid electrolyte tube is positioned and the bonding strength is secured.

Further, since the chamfered portion is provided on the outer peripheral edge of the solid electrolyte tube and the portion of the insulating ring facing the chamfered portion is made into an arcuate surface to eliminate the sharp portion, the gap between the two is filled in this portion. Stress concentration does not act on the glass to be treated.

Further, by forming the thickness of the open end of the solid electrolyte tube to be thicker than the thickness of the current-carrying portion of the battery, the mechanical strength at the joint between the solid electrolyte tube and the insulating ring can be increased. Therefore, even if an extra external force is applied to the solid electrolyte tube, the force is received by the open end formed in the wall thickness of the solid electrolyte tube, and the force on the joint is relieved. The reliability of can be secured.

Also, the open end of the solid electrolyte tube and the current-carrying part are formed by a predetermined inclined surface, and the end of the inclined surface on the current-carrying part side is set at the position where the mat of the conductive material for anode is present. By this, the breakage position of the solid electrolyte tube at the time of abnormality is specified. That is, the breakage of the solid electrolyte tube occurs at the position where the thickness of the solid electrolyte tube changes, that is, at the end portion of the inclined surface on the current-carrying portion side. At this time, since the fractured portion is covered with the mat from the outer periphery, the progress of fracture such as cracks is suppressed. Moreover, in this case, even if sodium spills out of the solid electrolyte tube due to destruction, the spilled sodium reacts with sulfur in the mat to become sodium polysulfide, so that the sodium can be prevented from flowing out. .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment embodying the invention of claims 1 and 2 will be described below with reference to the drawings.

As shown in FIG. 3, an anode lid 1 is attached to the lower end of an anode container 1 formed in a cylindrical shape, and an anode terminal 3 is attached to the outer surface of the upper portion. The insulating ring 4 is made of α-alumina and is joined to the upper end portion of the anode container 1. Solid electrolyte tube 5 having a bottomed cylindrical shape
Is formed of β-alumina, and the upper end portion of the glass 2 is formed by interposing the glass 24 on the inner peripheral surface of the insulating ring 4.
It is joined by 4. The anode chamber 6 is formed by the anode container 1 and the solid electrolyte tube 5, and is made of a graphite mat impregnated with sulfur as an anode acting substance, and a conductive material 7 for an anode.
Is stored.

The cathode lid 8 is attached to the upper end surface of the insulating ring 4, and the cathode terminal 9 is attached to the upper surface thereof. The cathode chamber 10 is formed by an insulating ring 4, a solid electrolyte tube 5 and a cathode lid 8, and the cathode chamber 10 contains sodium 11 which is a cathode active substance.

1 and 2 are partial cross-sectional views showing a glass bonding structure between the solid electrolyte tube 5 and the insulating ring 4, which are shown upside down. As shown in both figures, the upper part (the lower part in the figure), which is the open end of the solid electrolyte tube 5, is a thick part 12 to improve the strength, and a chamfered part 13 is formed on the outer peripheral edge of the upper part. It is provided.

On the other hand, on the inner peripheral surface of the insulating ring 4, there is provided an engaging portion 14 as an L-shaped first opposing surface, which is the solid electrolyte tube 5.
The solid electrolyte tube 5 is positioned at a vertical position by its inner top surface 14a and inner peripheral surface 14b. In the gap between the inner peripheral surface 14b of the locking portion 14 and the outer peripheral surface 5b of the solid electrolyte tube 5, a thickness of 50 to 200 μm is provided.
A thin-walled filling portion 19 of about m of glass is formed. Since the outer peripheral surface 5b of the solid electrolyte tube 5 is smoothly finished by surface grinding, the gap forming the thin wall filling portion 19 is maintained at a constant level, and the glass thin wall filling portion 19 is maintained.
Has a constant thickness.

An arcuate surface 15 is formed at a boundary portion (corner portion) between the inner top surface 14a and the inner peripheral surface 14b so as to face the chamfered portion 13 of the solid electrolyte tube 5.
Between the chamfered portion 13 and the arcuate surface 15, glass is filled to form a corner filling portion 16. And by providing the chamfered portion 13 and the arcuate surface 15,
The corner filling portion 16 is prevented from receiving stress concentration.

Further, an end chamfered portion 17 is provided at an end of the inner top surface 14a, and an end glass reservoir 18 is formed between the inner top surface 14a and the upper surface of the solid electrolyte tube 5, and a cathode action which contacts this portion is formed. It improves the corrosion resistance to the substance sodium.

Further, the insulating ring 4 has an inclined surface 21 on the inner peripheral surface of the lower end thereof, and a glass filling notch 20 is formed as a second facing surface facing the outer peripheral surface 5b of the solid electrolyte tube 5. There is. The notch 20 and the outer peripheral surface 5 of the solid electrolyte tube 5
The gap between b and b is sufficiently wider than the gap between the engaging portion 14 and the solid electrolyte tube 5, and therefore this portion becomes the thick glass filling portion 22 and sufficient bonding strength can be obtained.

When the solid electrolyte tube 5 and the insulating ring 4 are bonded to each other by glass, as shown in FIG. 2, the glass filling notch 20 of the insulating ring 4 and the outer peripheral surface 5b of the solid electrolyte tube 5 are connected.
A preformed glass ring 23 is placed in the space between and to heat and melt it. Then, as shown in FIG. 1, the molten glass flows downward in the figure, and the inner peripheral surface 14 b of the locking portion 14 of the insulating ring 4 and the outer peripheral surface 5 of the solid electrolyte tube 5 are caused.
It reaches the end chamfered portion 17 through a narrow gap with b. Between the end chamfered portion 17 and the upper end surface 5a as the open end surface of the solid electrolyte tube 5, a glass pool 18 due to surface tension is formed.
Is formed.

In this way, an end glass pool 18 made of glass is provided between the solid electrolyte tube 5 and the insulating ring 4,
Corner filling section 16, thin wall filling section 19, and thick wall filling section 2
And 2 are integrally formed. Then, the solid electrolyte tube 5 and the insulating ring 4 are joined by these glass joints.

As described above, in this embodiment, the L-shaped locking portion 14 is formed so as to closely face the outer peripheral surface 5b and the upper end surface 5a of the upper end portion of the solid electrolyte tube 5. Therefore, positioning of the solid electrolyte tube 5 in the axial direction and the direction orthogonal thereto is performed by the locking portion 14, and a jig for positioning is not required, which facilitates manufacturing. Moreover, the bonding strength between the insulating ring 4 and the solid electrolyte tube 5 is ensured by the thick filling portion 22 filled with a large amount of glass 24, and sufficient bonding strength can be obtained. Moreover, since the glass bonding portion is L-shaped as a whole, it can withstand external force from each direction and can improve reliability against thermal stress and mechanical stress.

Further, in the corner filling portion 16, the solid electrolyte tube 5 is provided with the chamfered portion 13 and the insulating ring 4 is provided with the arcuate surface 15, so that there is no sharp portion or sharp corner portion, and the solid electrolyte is eliminated. When a stress is applied to the tube 5 and the insulating ring 4, the stress is dispersed, the partial stress concentration is relieved, and there is no risk of cracking.

At the time of operation of the sodium-sulfur battery, high temperature sodium comes into contact with the end glass puddle 18, but as described above, since the glass puddle 18 has a large joint and a large surface area, this part is formed. Sufficient chemical resistance and durability are exhibited in.

The solid electrolyte tube 5 itself is the insulating ring 4.
Since the thick portion 12 is formed at the joint portion with, the mechanical strength of this portion is high, and the solid electrolyte tube 5 is less likely to be damaged. Furthermore, since the outer peripheral surface 5b of the solid electrolyte tube 5 is smoothly finished by surface processing,
The narrow gap between the outer peripheral surface 5b and the inner peripheral surface 14b of the notch engaging portion 14 can be maintained at a predetermined value, and the flowability and filling of the glass can be ensured. (Second Embodiment) Next, an embodiment in which the invention described in claims 3 and 4 is embodied will be described with reference to FIGS.

The solid electrolyte tube 5 has a constant inclined surface 26 between the current-carrying portion 25 of the battery and the junction of the insulating ring 4 such that the thickness thereof becomes thicker toward the insulating ring 4 side. Then, with respect to the thickness D ₁ of the energizing portion 25, the opening end portion 2
The wall thickness D _{2 of} 7 is the thickest. In this way, by increasing the thickness of the solid electrolyte tube 5 at the joint between the solid electrolyte tube 5 and the insulating ring 4, the mechanical strength of the solid electrolyte tube 5 at this portion is increased and the reliability of the joint is improved. Let

The boundary line B at the end of the inclined surface 26 on the side of the current-carrying portion 25 is the graphite mat 7a of the conductive material 7 for anode.
It is located in the part of. Therefore, the portion of the boundary line B forming the circumferential shape is the weakest portion of the solid electrolyte tube 5,
When an external force is applied to the solid electrolyte tube 5 due to an abnormality or the like, the solid electrolyte tube 5 is likely to be cracked or damaged. Therefore, the broken portion of the solid electrolyte tube 5 is specified. And
Even if breakage occurs in this portion, since the outer peripheral portion is covered with the conductive material for anode 7, the progress of breakage is prevented.

The ratio of the length of the current-carrying portion 25 to the length of the thick portion of the solid electrolyte tube 5 on the open end portion 27 side is 4 to 8.
It is desirable to be in the range from the viewpoint of maintaining the strength of the opening end portion 27 and securing the area of the conducting portion 25.

In this embodiment, the solid electrolyte tube 5 and the insulating ring 4 are formed by forming the wall thickness D ₂ at the open end 27 of the solid electrolyte tube 5 to be thicker than the wall thickness D _{1 at} the current-carrying portion 25 of the battery. Solid electrolyte tube 5 at the joint with
The mechanical strength of can be increased. For this reason, even if an extra external force is applied to the solid electrolyte tube 5, the force is supported by the open end portion 27 of the solid electrolyte tube 5 formed in this thickness, and the force on the joint portion is relaxed. As a result, it is possible to ensure the reliability of the joining at this joining portion.

In addition, if the wall thickness of the solid electrolyte tube 5 at the joint is increased, the wall thickness D ₁ of the current-carrying portion 25 can be made thinner than the normal wall thickness. In this case, the electrical resistance of the solid electrolyte tube 5 in the energization section 25 can be reduced. Therefore, the charging / discharging efficiency of the battery can be improved, and the temperature control associated with charging / discharging can be easily performed.

Further, the open end portion 27 of the solid electrolyte tube 5 and the current-carrying portion 25 are connected by a predetermined inclined surface 26, and the boundary line B of the end portion of the inclined surface 26 on the current-carrying portion 25 mat is formed. It was set at the position where 7a was present. Therefore, the breakage position of the solid electrolyte tube 5 at the time of abnormality is specified. That is, the breakage of the solid electrolyte tube 5 occurs at the position where the thickness of the solid electrolyte tube 5 changes, that is, at the boundary line B which is the end of the inclined surface 26 on the side of the current-carrying portion 25.

At this time, since the mat 7a is housed in a compressed state, the pressure of the mat 7a causes the solid electrolyte tube 5 to move.
Is biased inward. Therefore, the broken portion of the solid electrolyte tube 5 is supported by the mat 7a from the outer periphery of the solid electrolyte tube 5, and it is possible to prevent the destruction such as cracks from propagating to another portion. Moreover, the solid electrolyte tube 5 is destroyed due to the destruction.
The sodium flowing out from the inside reacts with the sulfur impregnated in the mat 7a to become sodium polysulfide, so that the sodium itself can be prevented from flowing out. Therefore, the safety of the battery can be improved.

Next, varied such that increasing the thickness D ₂ of the opening end portion 27 against the thickness D ₁ of the conducting portion 25, to measure the strength of the solid electrolyte tube 5. The results are shown in Table 1.
The strength was measured by the cantilever bending strength measuring method. That is, the solid electrolyte tube 5 joined to the insulating ring 4 is supported at the position of the insulating ring 4 so as to extend in the horizontal direction, and 90% of the length of the solid electrolyte tube 5 is applied with a predetermined load on the tip end thereof.
This load was gradually increased to obtain the strength until the solid electrolyte tube 5 and the glass 22 were broken.

[0037]

[Table 1] As shown in Test Examples 2 to 6 in Table 1, when the wall thickness of the open end with respect to the wall thickness of the current-carrying part of the solid electrolyte tube is made thicker, that is, when the ratio is set to 1.2 to 2.4. The strength is improved as compared with Test Example 1 in which the wall thickness is not changed.

The present invention is not limited to the above-described embodiments, but may be embodied by changing the configuration as follows, for example, without departing from the spirit of the present invention. (A) Changing the inclination angle of the end chamfer 17 of the insulating ring 4 to change the thickness and surface area of the end glass pool 18. (B) Changing the size of the chamfered portion 13 of the solid electrolyte tube 5 and the arcuate surface 15 of the insulating ring 4 to change the size of the corner filling portion 16 of the glass to change the degree of stress concentration relaxation. (C) The chamfered portion 13 of the solid electrolyte tube 5 is formed into an arcuate curved surface, or the arcuate surface 15 of the insulating ring 4 is formed into an inclined surface having a predetermined angle. (D) The number of glass layers having different thicknesses is changed by continuously forming a step between the thick-walled filling portion 22 and the thin-walled filling portion 19 of glass. (E) The thickness of the thick portion 12 of the solid electrolyte tube 5 may be further increased according to the size of the sodium-sulfur battery, or the like.
Or make it a little thinner and adjust accordingly. (F) The inclined surface 26 should be a smooth arc surface. (G) The solid electrolyte tube 5 is formed in a step shape at the position where the mat 7a exists, and the corner portion of the step portion is formed in a smooth arc shape.

[0039]

As described above in detail, according to the invention described in claim 1, the manufacturing is easy, the bonding strength can be secured, and the reliability of the bonding against the thermal stress and the mechanical stress is high. Produce an effect. Further, according to the invention described in claim 2, stress concentration applied to the glass filled between the chamfered portion of the solid electrolyte tube and the arcuate surface of the insulating ring is relaxed, and the durability of the glass bonding is improved. The effect is obtained.

Further, according to the invention of claim 3,
The mechanical strength at the joint between the solid electrolyte tube and the insulating ring can be increased, and the excellent reliability of the joint at this joint can be ensured.

According to the invention of claim 4, claim 3
In addition to the effect of the invention described above, it is possible to specify the breakage position of the solid electrolyte tube at the time of abnormality, prevent leakage of sodium, and improve the safety.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part showing a joint structure between a solid electrolyte tube and an insulating ring according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing a joint structure between a solid electrolyte tube and an insulating ring.

FIG. 3 is a cross-sectional view showing the structure of a sodium-sulfur battery.

FIG. 4 is a partially enlarged cross-sectional view showing a joint structure between a solid electrolyte tube and an insulating ring of a second embodiment.

FIG. 5 is a cross-sectional view showing the structure of a sodium-sulfur battery.

[Explanation of symbols]

1 ... Anode container, 4 ... Insulating ring, 5 ... Solid electrolyte tube, 1
3 ... Chamfered part of solid electrolyte tube, 14 ... Locking part as first facing surface, 15 ... Arc surface of insulating ring, 20 ... Glass filling notch as second facing surface, 25 ... Conducting part, Two
6 ... inclined surface, 27 ... opening end, D ₁ ... thickness of the conductive portion, D
₂ … The thickness of the open end.

Claims (4)

[Claims] 1. An insulating ring is joined to an end of a cylindrical anode container, and an open end of a solid electrolyte tube having a bottomed cylindrical shape is arranged on an inner peripheral surface of the insulating ring to form an insulating ring. The solid electrolyte tube is a junction structure between the solid electrolyte tube and the insulating ring in the sodium-sulfur battery joined via glass between the solid electrolyte tube and the inner peripheral surface of the insulating ring, the opening end portion of the solid electrolyte tube An L-shaped first facing surface that closely faces the outer peripheral surface and the opening end surface, and a second facing surface that faces the outer peripheral surface of the opening end with a distance wider than the distance between the first facing surface and the solid electrolyte tube. And a bonding surface between a solid electrolyte tube and an insulating ring in a sodium-sulfur battery. 2. The chamfered portion is provided on the outer peripheral edge of the solid electrolyte tube, and the corner portion of the first facing surface facing the chamfered portion is an arc-shaped surface. The joint structure of a solid electrolyte tube and an insulating ring in a sodium-sulfur battery. 3. An insulating ring is joined to an end of a cylindrical anode container, and an open end of a solid electrolyte tube having a bottomed cylindrical shape is arranged on an inner peripheral surface of the insulating ring to form an insulating ring. The solid electrolyte tube is joined via glass, the anode conductive material mat is housed between the anode container and the solid electrolyte tube, the mat is impregnated with sulfur, and the solid electrolyte tube contains sodium. In the sodium-sulfur battery, the thickness of the solid electrolyte tube at the open end is formed to be thicker than the thickness of the current-carrying portion of the battery. 4. The solid electrolyte tube has an open end and a current-carrying part formed on a predetermined inclined surface, and the end of the tilted surface on the current-carrying part side is set at a position where a mat of a conductive material for an anode is present. The sodium-sulfur battery according to claim 3, wherein: