JP2002184456A - Sodium-sulfur battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sodium-sulfur battery capable of stably achieving a high current density over a long time by reducing its internal resistance. SOLUTION: The sodium-sulfur battery 1 includes a negative electrode chamber 12 housing at least a negative electrode active material 12a containing sodium, a positive electrode chamber 13 housing a positive electrode active material 13a containing sulfur, and a solid electrolyte 14 located between the negative electrode chamber 12 and the positive electrode chamber 13 while isolating the negative electrode active material 12 from the positive electrode active material 13 and having conductivity for sodium ions. The positive electrode active material 13a is supplied to the positive electrode chamber 13 from a storage tank 32 connected to the positive electrode chamber 13 and is recovered from the positive electrode chamber 13.

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 fluid-type sodium-sulfur battery capable of obtaining a high output by flowing a positive electrode active material.

[0002]

2. Description of the Related Art In recent years, sodium-sulfur batteries have attracted particular attention as secondary batteries capable of storing large amounts of power. This sodium-sulfur battery uses sodium (Na) as an electrode active material on the negative electrode side, sulfur (S) or a molten salt thereof (SCl ₄ ) as the electrode active material on the positive electrode side, and the like. A secondary battery in which substances are not mixed, and which operates at a high temperature of 300 to 400C, usually around 350C. This sodium-sulfur battery has advantages such as no self-discharge, high performance because the electrode active material is liquid, long life because the electrolyte is solid, and maintenance-free because it is completely sealed. It is expected to be the most promising as a next-generation high-power storage battery.

[0003] A general configuration of a sodium-sulfur battery is that one side is provided with molten metal sodium as a cathode active material and the other side is provided with molten sulfur as a positive electrode active material, and both are selectively permeable to sodium ions. Are separated by a solid electrolyte such as β-alumina having FIG. 6 shows a sectional configuration diagram of a conventional sodium-sulfur battery. The sodium-sulfur battery 100 has an outer cylinder 101, a solid electrolyte tube 103 accommodated in the outer cylinder 101, a safety tube 105 accommodated inside the solid electrolyte tube 103, and a solid electrolyte tube filled outside. The positive electrode active material 102 and the negative electrode active material 104 filled inside the solid electrolyte tube 103 are provided. The outer cylinder 101 is a bottomed cylindrical tube forming a current collector on the positive electrode side, and is made of, for example, stainless steel (SUS316L).
Etc.) or a nickel alloy. The solid electrolyte tube 103 is a bottomed cylindrical tube made of ceramics or the like having a property of selectively transmitting sodium ions (Na +). For example, β-alumina (Na ₂ O · 11Al ₂ O ₃ ) or Mg as a stabilizer
Β ″ -alumina (3Na ₂ O) to which O or Li ₂ O is added
16Al ₂ O ₃ ) or the like is used. Solid electrolyte tube 103
An insulating ring 1 made of a bonding material such as glass solder
07, and the insulating ring 107 is sandwiched between an upper flange provided on the safety pipe 105 and a lower flange provided on the outer cylinder 101, and the solid electrolyte pipe 10
3 is integrally connected and fixed to the outer cylinder 101 and the safety pipe 105, and is insulated from each other.
Is used to seal the inside. The material is α with high insulation
-Made of alumina or the like.

[0004] The safety tube 105 is a bottomed cylindrical tube made of a material having high corrosion resistance, for example, stainless steel (SUS304 or the like), aluminum, or the like, and serving as a negative electrode current collector. A pore 106 is formed at the bottom so that the negative electrode active material 104 can flow into the safety tube 105 and flow out to the outside. Therefore, the solid electrolyte tube 103 and the safety tube 10
5, the amount of the negative electrode active material 104 existing in the gap 110
It can be kept below a certain amount. Sulfur (S) or molten salt (S) is provided between the outer cylinder 101 and the solid electrolyte tube 103.
A positive electrode active material 102 made of Cl ₄ );
The inside of the solid electrolyte tube 103 is filled with a negative electrode active material 104 made of sodium. These positive electrode active materials 1
02 and the negative electrode active material 104 are separated by a solid electrolyte tube 103.

Next, sulfur (S) is used as the positive electrode active material 102.
The charge / discharge reaction of the sodium-sulfur battery 100 in the case of using is described below. The discharge reaction at the negative electrode of the sodium-sulfur battery 100 in this case is as shown in (Equation 1) below. That is, the negative electrode active material 10
Sodium (Na), which is 2, emits electrons (e ⁻ ) to generate sodium ions (Na ⁺ ). Electron (e ^-)
Flows through the safety tube 105 to the external circuit, and sodium ions (Na ⁺ ) are selectively transmitted through the solid electrolyte tube 103 and transported to the positive electrode active material 102.

On the other hand, the discharge reaction at the positive electrode is as shown in the following (Equation 2). That is, the sodium ions (Na ⁺ ) entering the positive electrode active material 102 are sulfur (S),
And reacts with electrons (e ⁻ ) supplied from an external circuit,
Produces sodium polysulfide (Na ₂ S _x ). When charging the sodium-sulfur battery 100, a reaction opposite to the discharge reaction, that is, a reaction in the opposite direction to the arrow in both (Equation 1) and (Equation 2) occurs, and sodium (Na) and sulfur (S) are generated.

(Equation 1): 2Na → 2Na ⁺ + 2e ⁻ (Equation 2): 2Na ⁺ + xS + 2e ⁻ → Na ₂ S _X

[0008]

In order to realize high efficiency in a sodium-sulfur battery, how to reduce the internal resistance is a problem. In order to reduce the sulfur content, sulfur of the positive electrode active material is mixed with sodium polysulfide having a small resistance. However, in the sodium-sulfur battery 100 having the above structure, the volume of the positive electrode chamber is constant,
As the amount of sodium polysulfide added increases, the internal resistance decreases, but there is a problem that the capacity of the battery decreases. Therefore, in the above-mentioned sodium-sulfur battery 100, it was difficult to extract a large current because the internal resistance was not sufficiently reduced without decreasing the amount of sodium polysulfide added.

The present invention has been made in view of the above circumstances, and has as its object to provide a sodium-sulfur battery capable of stably obtaining a high current density for a long time by reducing internal resistance.

[0010]

In order to achieve the above object, the present invention employs the following constitution.

According to the first aspect of the present invention, a negative electrode chamber containing at least a negative electrode active material containing sodium, a positive electrode chamber containing a positive electrode active material containing sulfur, and the negative electrode chamber and the positive electrode chamber. A sodium-sulfur battery including a negative electrode active material and a positive electrode active material that are located in between, and a solid electrolyte having conductivity for sodium ions, wherein the positive electrode active material is contained in the positive electrode chamber. A sodium-sulfur battery characterized by having a flow structure is provided as a means for solving the above-mentioned problem.

According to the structure of the present invention, since the positive electrode active material flows continuously in the positive electrode chamber, the sulfur valency of the positive electrode active material in the vicinity of the current collector on the positive electrode side may vary greatly. In addition, it is possible to prevent a decrease in battery capacity due to a decrease in performance of the positive electrode active material.

Next, the invention according to claim 2 is provided with a storage tank connected to the positive electrode chamber for recovering the positive electrode active material from the positive electrode chamber and supplying the positive electrode active material to the positive electrode chamber. A sodium-sulfur battery according to claim 1 is a means for solving the above problem.

According to the structure of the present invention, since the storage tank for storing the cathode active material in advance is provided, the cathode active material having a constant sulfur valence can be supplied to the cathode chamber.

Next, the invention according to claim 3 is that the storage tank includes a gas supply source connected to the storage tank and supplying a gas for pumping the positive electrode active material into the storage tank. A sodium-sulfur battery according to claim 2 is a means for solving the above problem.

According to the structure of the present invention, since the method of supplying the positive electrode active material to the positive electrode chamber is gas pressure feeding,
The structure of the sodium-sulfur battery can be simplified to reduce the cost.

Next, according to a fourth aspect of the present invention, the supply rate of the positive electrode active material by the positive electrode active material supply means is 100 m.
The sodium-sulfur battery according to any one of claims 1 to 3, wherein the range is 1 / min to 10 ml / min.

According to such a configuration, it is possible to optimize the amount of the positive electrode active material used for the reaction by appropriately setting the speed of the positive electrode active material passing through the positive electrode chamber.

Next, according to a fifth aspect of the present invention, there is provided a sodium-sulfur battery according to any one of the first to fourth aspects, wherein the positive electrode active material is sodium polysulfide. Was the solution.

Next, according to a sixth aspect of the present invention, there is provided a sodium-sulfur battery according to the fifth aspect, wherein a sulfur valence of the positive electrode active material is in a range of 5 to 40. Was the solution.

According to a seventh aspect of the present invention, there is provided a sodium-sulfur battery according to the sixth aspect, wherein the positive electrode active material has a sulfur valence of 5 or more and 8 or less. Means.

According to this configuration, by setting the sulfur valence of sodium polysulfide passing through the positive electrode chamber to the above range, the sodium polysulfide does not solidify and the specific resistance of sodium polysulfide is reduced. can do.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. However, the present invention is not limited to the following embodiments.

FIG. 1 is a sectional view of a sodium-sulfur battery according to an embodiment of the present invention. In this figure, a sodium-sulfur battery 1 operates as a secondary battery and can be charged and discharged. Unit 10 and the battery body 1
And a positive electrode active material recovery / supply device 30 connected to a positive electrode active material for supplying and recovering a positive electrode active material made of sulfur or the like.

The battery body 10 is provided with a negative electrode chamber 12 containing a negative electrode active material 12a containing sodium and a positive electrode chamber 13 containing a positive electrode active material 13a containing sulfur. In addition, a solid electrolyte tube 14 having conductivity for sodium ions is disposed between the negative electrode active material 12a and the positive electrode active material 13a, and separates them.

The negative electrode chamber 12 is composed of a cylindrical guide tube 16 and a bottomed cylindrical safety tube 17 joined to the lower open end thereof. A certain sodium is stored. The solid electrolyte tube 14 has a bottomed cylindrical shape as shown in FIG. 1, and is made of a material such as ceramics or glass having conductivity to sodium ions. More specifically, for example, β-alumina (Na ₂ O · 11Al
₂ O ₃₎ or, MgO as a stabilizer, beta LiO ₂ or the like is added "-. Alumina _{(3Na 2 O · 16Al 2 O} 3) or the like is used solid electrolyte tube 14 so as to encircle the safety tube 17 The solid electrolyte tube 14 and the safety tube 17 have a predetermined gap therebetween.

At the other end (upper end in the figure) of the guide tube 16, a negative electrode active material supply pipe 18 for supplying the negative electrode active material 12a to the negative electrode chamber 12 as necessary is inserted. The tip of the negative electrode active material supply pipe 18 from which the negative electrode active material 12 a is discharged is disposed near the bottom of the safety pipe 17 at the tip of the guide pipe 16. On the other hand, the other end of the negative electrode active material supply pipe 18 is connected to an external negative electrode active material supply source 25. Also,
A rod-shaped insertion heater 19 for heating the negative electrode active material 12a supplied to the negative electrode chamber 12 is inserted from the upper end of the negative electrode active material supply pipe 18 into the inside. The negative electrode active material supply pipe 18 is removed or sealed when the battery is used so that the negative electrode chamber 12 is sealed.

The upper part of the solid electrolyte tube 14 and the guide tube 1
A protective tube 22 having a bottomed cylindrical shape is provided so as to surround a lower portion of the solid electrolyte tube 6, and a lower portion of the solid electrolyte tube 14 is exposed to the positive electrode chamber 13 from the bottom. A ceramic filler 23 is filled between the protective tube 22 and the solid electrolyte tube 14 and the guide tube 16, and the sulfur-containing positive electrode active material 13a is filled with the protective tube 22 and the ceramic filler 23.
This prevents the guide tube 16 from being corroded.

The positive electrode chamber 13 has a substantially cylindrical outer tube 20 having a bottom.
And a positive electrode container 21 having a cylindrical shape with a bottom disposed therein. The positive electrode container 21 is inserted into a hole provided at the bottom of the outer tube 20 and its side surface is joined to the bottom of the outer tube 20 to be integrated. Also,
A substantially funnel-shaped cathode active material lead-out portion 24 is joined to the outer surface of the bottom of the outer tube 20 with its wide-open side facing the bottom surface of the outer tube 20. That is, the bottom portion of the positive electrode container 21 inserted into the bottom surface of the outer tube 20 is disposed in a space surrounded by the bottom surface of the outer tube 20 and the positive electrode active material outlet 24. FIG.
As shown in the figure, a cathode active material supply port 27 for supplying the cathode active material 13a to the cathode chamber 13 is provided on the side surface of the outer tube 20.

The solid electrolyte tube 14 is provided inside the positive electrode container 21.
And a conductive auxiliary material 15 such as a carbon fiber cloth provided so as to surround the periphery thereof. That is, the conductive auxiliary material 15 is arranged so as to surround the solid electrolyte tube 14, and the positive electrode container 21 is arranged so as to surround the outer periphery of the conductive auxiliary material 15. Although the positive electrode container 21 and the conductive auxiliary material 15 are arranged so as to be in close contact with each other, a gap of about 1 mm is provided between the conductive auxiliary material 15 and the solid electrolyte tube 14. This is due to the stress caused by thermal deformation of the internal or external parts of the solid electrolyte tube 14.
4 is a structure for protecting. The positive electrode active material 13 a is injected into the positive electrode chamber 13, which is a region surrounded by the solid electrolyte tube 14 and the outer tube 20, and is impregnated in the conductive auxiliary material 15. In addition, the bottom (lower end in the figure) of the positive electrode container 21
Are provided with pores communicating the positive electrode container 21 and the inside of the positive electrode active material lead-out portion 24.

In the above configuration, the flange provided at the open end (upper end in the figure) of the outer tube 20 and the flange supporting the guide tube 16 are connected via the packing 28 in an electrically insulated state. Thus, the positive electrode chamber 13 is sealed. The method of connecting the outer tube 20 and the guide tube 16 is shown as an example, and is not limited to the above method as long as it can achieve electrical insulation and airtightness. For example,
A ring made of an insulating material such as α-alumina may be provided between the two flanges, and these may be joined and integrated by a joining material such as glass solder.

The positive electrode active material supply / recovery device 30 includes a storage tank 32.
And a gas supply source 31 for supplying a gas for pumping the positive electrode active material 13a stored in the storage tank 32. Two pipes 3 provided in the storage tank 32
Reference numerals 3 and 34 are respectively connected to a positive electrode active material supply port 27 provided on a side surface of the outer tube 20 and a positive electrode active material outlet 24 disposed at the bottom of the outer tube 20. These pipes 33 and 34 are provided with check valves 35 and 36 in their respective paths, so that the positive electrode active material 13a flowing inside does not flow backward.

The above-described positive electrode active material supply / recovery device 30 supplies a gas such as argon from a gas supply source 31 to a storage tank 32 and applies pressure to the positive electrode active material 13 a stored in the storage tank 32, The positive electrode active material 13a is pressure-fed to the pipe 33, and the positive electrode active material 13a is supplied to the positive electrode chamber 13 through the positive electrode active material supply port 27 on the side surface of the outer tube 20. Also,
The positive electrode active material 13a used for the reaction in the vicinity of the conductive auxiliary material 15 is recovered from the positive electrode chamber 13 through a pipe 34 connected to the positive electrode active material outlet 24, and stored in the storage tank 32.

Next, the flow of the positive electrode active material 13a in the battery body 10 will be described with reference to FIG. FIG. 2 is an enlarged cross-sectional configuration diagram illustrating a main part of the battery main body 10. The positive electrode active material 1 supplied from the storage tank 32 shown in FIG.
3a is introduced into the positive electrode chamber 13 from the side of the outer tube 20 via the positive electrode active material supply port 27 shown in FIG. The positive electrode active material 13a is filled in a portion surrounded by the positive electrode container 21 and the outer tube 20, and when the liquid surface reaches the opening end of the positive electrode container 21, it flows into the inside of the positive electrode container 21 and is impregnated with the conductive auxiliary material 15. Used for the reaction during charging and discharging. Thereafter, the positive electrode active material 13a is guided to the positive electrode active material lead-out part 24 through a hole provided at the bottom of the positive electrode container 21, led out of the battery main body part 10, and stored in the storage tank 32 through the pipe 34 shown in FIG. Is done.

On the other hand, the negative electrode active material 12a spreads through a communication hole 17a provided at the bottom of the safety tube 17 into the gap between the safety tube 17 and the solid electrolyte tube 14 by capillary action, and is ionized to cause the solid electrolyte tube 14 to be ionized. Conductive, positive electrode active material 1
It is subjected to a reaction with 3a. By providing the safety tube 17 in this way, even when the solid electrolyte tube 14 is broken, the site where the positive electrode active material 13a and the negative electrode active material 12a directly react can be suppressed to a small range. . Therefore, heat generation when these active materials react directly can be minimized.

The sodium-sulfur battery 1 is of a fluid type in which sulfur and / or sodium polysulfide as a positive electrode active material continuously passes through the inside of the positive electrode chamber 13 during charging or discharging. With such a configuration, the positive electrode active material 13a to be subjected to the reaction near the conductive auxiliary material 15 is continuously flowed in a specific direction (downward in the drawing). The sulfur valency of the active material 13a does not greatly change. Thereby, it is possible to stably discharge at a high current density for a long time. The reason will be described in detail below.

At the time of discharging on the positive electrode side of the sodium-sulfur battery 1, the reaction shown in the above-mentioned (formula 2) proceeds. That is, sulfur, which is a positive electrode active material, is transformed into sodium polysulfide. Alternatively, a reaction in which the sulfur valence of sodium polysulfide decreases due to the reaction between sodium polysulfide and sodium ions proceeds.

FIG. 3 shows the result of measuring the specific resistance of the positive electrode active material in a sodium-sulfur battery having a general configuration. As shown in this figure, the specific resistance of the positive electrode active material sharply decreases as the sulfur valence in the positive electrode active material decreases. In particular, in the region where the sulfur valence is 8 or less, the specific resistance is 10 (Ωc
m) This can be confirmed from the graph shown in FIG. The graph of FIG. 4 shows the results of measuring the current density and the voltage while changing the sulfur valence of the positive electrode active material. As shown in this graph, the smaller the sulfur valence of the positive electrode active material, the smaller the voltage drop with respect to the current density. Therefore, it can be seen that the internal resistance of the sodium-sulfur battery is low in a region where the sulfur valence is small, and that discharge at a high current density is possible.

However, when the sulfur valence of the positive electrode active material 13a is 2.7 or less, Na _{2 is} contained in the positive electrode active material 13a.
A solid phase of S ₂ results. This is caused by the melting point of Na ₂ S ₂ generated with a decrease in the sulfur valence is about 900 ° C., the operating temperature of the sodium-sulfur battery is about 350 ° C.. Even if this solid phase occurs, the composition of the liquid layer is constant so that the electromotive force does not decrease, but since it does not melt at the operating temperature of the sodium sulfur battery, the active material decreases and the battery capacity decreases. . From this,
The sulfur valence of the positive electrode active material needs to be in a range where the above-mentioned capacity reduction does not occur, and specifically, it is preferably 5 or more. Further, if the sulfur valence is too large, the internal resistance becomes large. Therefore, the sulfur valence is preferably set to 40 or less, more preferably 8 or less which makes the specific resistance 10 (Ωcm) or less.

When the sodium-sulfur battery is discharged as described above, the sulfur valence of the positive electrode active material decreases. Since the lower limit of the sulfur number at which the performance of the battery does not decrease is 5, the lower the sulfur number initially set, the sooner the lower limit is reached. That is, when the sulfur valence is reduced, the battery capacity is reduced. According to the sodium-sulfur battery 1 of the present embodiment, the positive electrode active material 13a flows continuously in the positive electrode chamber 13 as described above. It is possible to supply the positive electrode active material 13a having a small sulfur valence both at the time of discharging. That is, the positive electrode active material 13a having a small specific resistance is always supplied to the vicinity of the conductive auxiliary material 15 where the reaction at the time of charging and discharging proceeds. Therefore, the sodium-sulfur battery of the present embodiment can reduce the internal resistance and can operate at a high current density for a long time without a decrease in the performance of the battery due to a change in the sulfur valence of the positive electrode active material 13a. It is.

The above-mentioned sodium-sulfur battery 1 can be used as a module by combining a plurality of batteries.
The number may be changed as appropriate according to the target power scale, and power of several kW to several MW can be stored according to the number. If the sodium-sulfur battery 1 is used as a module as described above, the storage tank 32
Can be shared by a plurality of battery main units 10, and a module can be configured efficiently.

[0042]

EXAMPLES Hereinafter, the effects of the present invention will be described in more detail with reference to Examples, but the following Examples do not limit the present invention in any way.

First, sodium was charged into the sodium-sulfur battery 1 shown in FIG. 1 as a negative electrode active material, and sodium sulfide was charged as a positive electrode active material. At this time, the sulfur valency of sodium sulfide was set to 5. Next, the supply rate of the positive electrode active material from the storage tank to the positive electrode chamber was set to 40 ml / min, and the sodium-sulfur battery was discharged at an operating temperature of 350 ° C. to measure the power density over time.

Comparative Example Next, for comparison, a sodium-sulfur battery having a conventional configuration shown in FIG. 6 was filled with sodium as a negative electrode active material and sodium sulfide as a positive electrode active material. At this time, the sulfur valence of sodium sulfide was set to 5, which was the same as that in Example 1. The sodium battery was discharged at an operating temperature of 350 ° C., and a change in power density over time was measured.

FIG. 5 shows the measurement results of the power densities of the above Examples and Comparative Examples. The power density of the sodium-sulfur battery of the comparative example indicated by reference numeral 41 in FIG. 5 decreases over time, and after 90 minutes, the power density decreases to about two thirds. In contrast, the power density of the sodium-sulfur battery according to the embodiment of the present invention indicated by reference numeral 40 in FIG. 5 does not decrease in this way, and the power density is almost constant even after 130 minutes.

In this example and the comparative example, the sulfur valence of sodium sulfide, which is a positive electrode active material, is reduced as described above in order to discharge at a high current density. For this reason,
In the conventional sodium-sulfur battery, as shown in FIG. 5, the power is reduced at an early stage, but in the sodium-sulfur battery of the above embodiment, despite the small sulfur valence,
No decrease in power density has appeared. Therefore, it was confirmed that the sodium-sulfur battery of the present invention can be discharged at a high current density for a long time.

[0047]

As described in detail above, the sodium-sulfur battery of the present invention comprises a negative electrode chamber containing at least a negative electrode active material containing sodium and a positive electrode chamber containing a positive electrode active material containing sulfur. A sodium-sulfur battery including a solid electrolyte that is located between the negative electrode chamber and the positive electrode chamber, separates the negative electrode active material and the positive electrode active material, and has conductivity for sodium ions. Therefore, since the positive electrode active material has a flow structure in the positive electrode chamber, the sulfur valence of the nearby positive electrode active material does not greatly change, and the battery capacity decreases due to the deterioration of the performance of the positive electrode active material. Can be prevented.

Next, the sodium-sulfur battery of the present invention is provided with a storage tank connected to the positive electrode chamber for recovering the positive electrode active material from the positive electrode chamber and supplying the positive electrode active material to the positive electrode chamber. Therefore, a positive electrode active material having a constant sulfur valence can be supplied to the positive electrode chamber by providing a storage tank for storing the positive electrode active material in advance. This allows
Long-term discharge at high current density is possible.

Next, the sodium-sulfur battery of the present invention has a configuration in which the storage tank is provided with a gas supply source connected to the storage tank and supplying a gas for pumping the positive electrode active material into the storage tank. Therefore, the structure of the sodium-sulfur battery can be simplified and cost can be reduced.

Next, in the sodium-sulfur battery of the present invention, the supply rate of the positive electrode active material by the positive electrode active material supply means is one.
Since the flow rate is set in the range of 00 ml / min to 10 ml / min, the speed of the positive electrode active material passing through the current collector on the positive electrode side can be set in an appropriate range to optimize the amount of the positive electrode active material used for the reaction. it can. Therefore, power can be taken out stably for a long time.

Next, in the sodium battery of the present invention, the positive electrode active material is sodium polysulfide, and its sulfur number is 5
By setting the range to 40 or more, or 5 to 8 or less, sodium polysulfide does not solidify and the specific resistance of sodium polysulfide can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of a sodium-sulfur battery according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional configuration diagram illustrating a portion where a positive electrode active material of the sodium-sulfur battery illustrated in FIG. 1 flows.

FIG. 3 is a graph showing the relationship between the sulfur valency of a positive electrode active material and its specific resistance.

FIG. 4 is a graph showing the relationship between the sulfur valency of a positive electrode active material and the IV characteristics of a sodium-sulfur battery.

FIG. 5 is a graph showing changes in power density over time of the sodium-sulfur batteries of the example and the comparative example.

FIG. 6 is a cross-sectional view illustrating an example of a configuration of a conventional sodium-sulfur battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sodium sulfur battery 12 Negative electrode chamber 12a Negative electrode active material 13 Positive electrode chamber 13a Positive electrode active material 14 Solid electrolyte tube 15 Conductive auxiliary material 31 Gas supply source 32 Storage tank

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Koichi Tanimoto 2-1-1 Shinhama, Arai-machi, Takasago-shi, Hyogo F-term in Takasago Research Laboratory, Mitsubishi Heavy Industries, Ltd. 5H029 AJ06 AK05 AL13 AM14 AM15 BJ02 BJ24 DJ02 DJ06 DJ09 HJ00

Claims (7)

[Claims] A negative electrode chamber containing at least a negative electrode active material containing sodium; a positive electrode chamber containing a positive electrode active material containing sulfur; and the negative electrode positioned between the negative electrode chamber and the positive electrode chamber. A sodium-sulfur battery including an active material and a solid electrolyte that isolates the positive electrode active material and has conductivity for sodium ions, comprising a flow structure of the positive electrode active material in the positive electrode chamber. Sodium sulfur battery. 2. The storage device according to claim 1, further comprising: a storage tank connected to the cathode chamber for recovering the cathode active material from the cathode chamber and supplying the cathode active material to the cathode chamber. Sodium-sulfur battery. 3. The sodium storage tank according to claim 2, wherein the storage tank includes a gas supply source connected to the storage tank to supply a gas for pumping the positive electrode active material into the storage tank. Sulfur battery. 4. The sodium according to claim 1, wherein a supply rate of the positive electrode active material from the storage tank to the positive electrode chamber is in a range of 100 ml / min to 10 ml / min. Sulfur battery. 5. The sodium-sulfur battery according to claim 1, wherein the positive electrode active material comprises sulfur and sodium polysulfide. 6. The positive active material has a sulfur valence of 5 or more and 4 or more.
The sodium-sulfur battery according to claim 5, wherein the range is 0 or less. 7. The positive active material has a sulfur valence of 5 or more and 8 or more.
The sodium-sulfur battery according to claim 6, wherein: