JPH11329488A - Sodium-sulfur battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sodium-sulfur battery capable of preventing breakage of a solid electrolyte tube when the battery temperature falls and capable of being manufactured at a lower cost. SOLUTION: In this sodium-sulfur battery, a bottomed, cylindrical solid electrolyte tube 5 is housed within a bottomed, cylindrical positive-electrode container 1, an upper end part of the positive-electrode container 1 and an upper end part of the solid electrolyte tube 5 are joined/fixed together by an insulation ring 4, an upper end opening part of the insulation ring 4 is sealed up with a negative-electrode lid 6, a positive-electrode conducting material 7 impregnated with sulfur S as a positive-electrode active material is housed in a positive- electrode chamber R1 formed between the positive-electrode container 1 and the solid electrolyte tube 5, and sodium Na as a negative-electrode active material is housed in a negative-electrode chamber R2 formed within the solid electrolyte tube 5. A contractive bag body 10 easily contractible in the axial direction of the battery is provided between a bottom part upper surface of the positive- electrode container 1 and a bottom part under surface of the solid electrolyte tube 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a sodium-sulfur battery suitably used as a secondary battery for storing electric power.

[0002]

2. Description of the Related Art In a conventional sodium-sulfur battery, a bottomed cylindrical solid electrolyte tube made of β-alumina is accommodated inside a bottomed cylindrical anode container, and the anode container and the solid electrolyte tube are placed in the same. Are joined and fixed air-tight with an insulating ring, and the opening at the upper end of the insulating ring is sealed with a cathode lid. The anode chamber formed between the anode container and the solid electrolyte tube accommodates a thick cylindrical conductive material for the anode, such as a carbon mat impregnated with sulfur, as an anode active material. The internal cathode chamber contains sodium as a cathode active material.

[0003] At the time of discharge, 300 to 350 ° C
When heated, the molten sodium in the cathode chamber emits electrons to become sodium ions, passes through the solid electrolyte tube, moves to the anode chamber, and reacts with sulfur in the anode chamber and electrons that have passed through the external circuit. To generate sodium polysulfide and generate voltage. Further, at the time of charging, a reaction occurs in which sodium and sulfur are generated from sodium polysulfide, contrary to the time of discharging.

By the way, the conventional sodium-
In the sulfur battery, sodium polysulfide is easily deposited in a gap formed by the bottom upper surface of the anode container and the bottom lower surface of the solid electrolyte tube, and when the battery is heated, the temperature is lowered and the state is shifted to a stopped state. Due to the change in state of the deposited sodium polysulfide from liquid to solid and the difference in the coefficient of thermal expansion between the solid electrolyte tube and the anode container, stress acts on the solid electrolyte tube and the solid electrolyte tube is broken. There was a problem.

That is, since the anode container is formed of aluminum or the like and the solid electrolyte tube is formed of β-alumina or the like, the two have different coefficients of thermal expansion. Therefore, during the heating operation of the battery, the anode container expands more than the solid electrolyte tube, and the gap between the upper surface of the bottom of the anode container and the lower surface of the bottom of the solid electrolyte tube becomes larger. The gap shrinks as the container shrinks more than the solid electrolyte tube. However, if sodium polysulfide generated during the heating operation of the battery enters the gap in a molten state and remains there and solidifies from the molten state with a decrease in the temperature at which the battery is stopped, the solidified polysulfate Sodium sulfide prevented the dimensional change of the gap when the battery was stopped, and there was a possibility that the solid electrolyte tube was strongly compressed and damaged by the contraction of the anode container.

[0006] In order to solve such a problem, the present applicant has previously devised a sodium-sulfur battery in which a part of an anode container (outer container) is provided with a constriction-shaped easily deformable portion (particularly, JP-A-5-109433). This sodium-
In a sulfur battery, the solid electrolyte tube (β
Since the stress acting on the (alumina tube) is absorbed by the deformation of the easily deformable portion, the solid electrolyte tube is not strongly compressed, and the solid electrolyte tube is prevented from being damaged when the temperature is lowered.

[0007]

However, although the sodium-sulfur battery as described above is effective in preventing the solid electrolyte tube from being damaged, it is costly to process a constricted portion in the anode container. There was a new problem of passing. The present invention has been made in view of such a situation, and an object of the present invention is to prevent the solid electrolyte tube from being damaged when the battery temperature is lowered as described above, and to produce sodium at a lower cost. -To provide a sulfur battery.

[0008]

According to the present invention, a bottomed cylindrical solid electrolyte tube is housed inside a bottomed cylindrical anode container, and the upper end of the anode container and the upper end of the solid electrolyte tube are housed. With an insulating ring, and the upper end opening of the insulating ring is closed with a cathode lid, and sulfur as an anode active material is supplied to an anode chamber formed between the anode container and the solid electrolyte tube. A sodium-sulfur battery containing an impregnated conductive material for an anode and containing sodium as a cathode active material in a cathode chamber formed inside the solid electrolyte tube, wherein a bottom upper surface of the anode container and the solid electrolyte are contained. A sodium-sulfur battery is provided, in which a bag having a shrinkage property is provided between the bottom surface of the tube and the bottom surface of the tube so as to easily shrink in the axial direction of the battery.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the sodium-sulfur battery of the present invention, since a bag exists between the upper surface of the bottom of the anode container and the lower surface of the bottom of the solid electrolyte tube, sodium polysulfide enters the portion. Accumulation is prevented.
The bag has a contraction property such that the bag easily contracts in the axial direction (length direction) of the battery. Therefore, when the temperature of the battery decreases, the anode container shrinks, and the bottom surface of the anode container and the solid electrolyte tube When the gap with the lower surface of the bottom becomes small, the bag body easily contracts and deforms to follow this, absorbing the stress applied to the solid electrolyte tube. As a result, the solid electrolyte tube is not strongly compressed due to the stress caused by the contraction of the anode container, and the solid electrolyte tube is prevented from being damaged when the temperature of the battery is lowered. Also,
This sodium-sulfur battery has a narrower easily deformable portion formed in the anode container as described above,
Since the volume of the anode chamber can be increased, the volume energy density of the battery is increased, and production can be performed at low cost. Furthermore, since such a constricted portion is a weak point in strength, the absence of such a portion is excellent in strength.

Hereinafter, embodiments of the sodium-sulfur battery of the present invention will be specifically described with reference to the drawings. However, the present invention is not limited by these embodiments, and the gist of the present invention will be described. It should be understood that various changes, modifications, and the like can be made based on the ordinary knowledge of those skilled in the art without departing from the scope of the present invention.

FIG. 1 is an explanatory sectional view showing an example of the sodium-sulfur battery of the present invention. As shown in this figure,
The anode container 1 is formed in a cylindrical shape with a bottom by a cylindrical body 2 and a bottom plate 3 fitted and fixed to a lower end edge of the cylindrical body 2. The outer peripheral surface of an insulating ring 4 made of α-alumina is joined to the upper inner peripheral surface of the cylindrical body 2 by heat and pressure, and the upper outer periphery of a bottomed cylindrical solid electrolyte tube 5 made of β-alumina is adhered to the inner peripheral surface. The surfaces are bonded and fixed. A cathode lid 6 is joined and fixed to the upper end surface of the insulating ring 4. And this solid electrolyte tube 5
An anode chamber R1 is defined on the outside, and a cathode chamber R2 is defined on the inside.

An anode conductive material 7 made of a carbon mat or the like impregnated with sulfur S as an anode active material is accommodated in the anode chamber R 1. The cathode chamber R2 contains sodium Na as a cathode active material. Further, an inert gas G such as nitrogen gas or argon gas is sealed at a predetermined pressure in an upper space of the cathode chamber R2, and sodium Na is pressurized by the inert gas G.

The cathode lid 6 is brought into contact with sodium Na in the solid electrolyte tube 5 via a conductive member (not shown) to collect electricity on the cathode side. Then, at the time of discharge, sodium Na permeates through the solid electrolyte tube 5 as sodium ions and moves to the anode chamber R1 side.

The bottom upper surface of the anode container 1 and the solid electrolyte tube 5
A bag 10 having a characteristic structure of the present invention is provided between the bag 10 and the bottom lower surface of the bag. This bag body 10 is the anode container 1
In order to absorb the stress applied to the bottom of the solid electrolyte tube 5 during the contraction of the battery, it is necessary to have a contractibility such that the battery easily contracts in the axial direction of the battery. In this example, the bag 10 is provided with the above-described contractility by disposing the spring 11 inside the bag 10.

As described above, due to the presence of the bag body 10, sodium polysulfide flows into a gap formed by the bottom upper surface of the anode container 1 and the bottom lower surface of the solid electrolyte tube 5 to deposit and solidify. Is prevented,
Further, when the temperature of the battery drops and the anode container 1 shrinks to reduce the gap, the bag 10 also deforms and shrinks accordingly, absorbing the stress applied to the bottom of the solid electrolyte tube 5.

The bag 10 is made of a material having excellent corrosion resistance and heat resistance because it comes into contact with a corrosive active material and is exposed to a temperature environment of about 300 to 350 ° C. when the battery is discharged. It needs to be. Specifically, it is preferable to use a packaging material made of stainless steel foil.

The bag body is not limited to the bag body having a spring disposed therein as described above. For example, the bag body may be filled with a stainless sponge instead of the spring, or gas may be sealed at a predetermined pressure. Alternatively, a bag provided with shrinkage may be used.

In the above-described example, the bag is manufactured separately from the battery structure. However, even if the bag is partially formed using the battery structure. Good. For example, FIG. 2 uses a flexible thin metal plate 13 having a portion corresponding to the bottom shape of the solid electrolyte tube 5, and the outer periphery of the thin metal plate 13 is welded to the anode container 1 by means such as welding.
This is an example in which the metal sheet 13 and the lower part of the anode container 1 form the bag body 12 by bonding to the inner peripheral surface of the bag. A gas may be sealed in the bag 12 at a predetermined pressure. The thin metal plate 13 is preferably made of the same material as the anode container 1, for example, an aluminum alloy is preferable.

In the present invention, it is preferable that the bag body and the bottom lower surface of the solid electrolyte tube are always in light contact with each other, but even if there is a slight gap between the two, the stress absorbing effect of the present invention can be obtained. Is not compromised. Further, the cross-sectional area in the cross section of the bag body is preferably substantially the same as or larger than the cross-sectional area in the cross section of the solid electrolyte tube, and as in the examples shown in FIGS. It may completely occupy the bottom.

[0020]

As described above, the sodium-sulfur battery of the present invention can prevent breakage of the solid electrolyte tube when the battery temperature drops, can be produced at low cost, and can also improve the strength of the anode container. It has a great effect.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing an example of an embodiment of the present invention.

FIG. 2 is an explanatory sectional view showing another example of the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Anode container, 2 ... Cylindrical body, 3 ... Bottom plate, 4 ... Insulation ring, 5 ... Solid electrolyte tube, 6 ... Cathode lid, 7 ... Conductive material for anode, 10 ... Bag, 11 ... Spring, 12 ... Bag , 13 ... metal sheet.

Claims (4)

[Claims] A bottomed cylindrical solid electrolyte tube is also housed inside a bottomed cylindrical anode container, and an upper end of the anode container and an upper end of the solid electrolyte tube are joined and fixed by an insulating ring, While closing the upper end opening of the insulating ring with a cathode lid, the anode chamber formed between the anode container and the solid electrolyte tube contains a conductive material for the anode impregnated with sulfur as an anode active material. A sodium-sulfur battery containing sodium as a cathode active material in a cathode chamber formed inside the solid electrolyte tube, wherein a battery is provided between a bottom upper surface of the anode container and a bottom lower surface of the solid electrolyte tube. Characterized in that a bag having a shrinkage property such that the bag body easily shrinks in the axial direction of the sodium is provided.
Sulfur battery. 2. The sodium-sulfur battery according to claim 1, wherein the bag body is provided with a spring to provide shrinkage. 3. The sodium-sulfur battery according to claim 1, wherein the bag body is filled with a stainless sponge to impart shrinkage. 4. The sodium-sulfur battery according to claim 1, wherein the bag body is provided with shrinkage by filling a gas therein at a predetermined pressure.