JP2002343422A - Sodium secondary battery and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the performance of a sodium secondary battery, restraining lowering and deteriorating the performance level of the sodium secondary battery, and to manufacture high-performance sodium secondary battery easily and safely. SOLUTION: A cylindrical partition plate 32 is arranged in a positive pole activator housing part B on the outer peripheral side of a cylindrical body 4'. A gap 33 is formed between the outer surface of the cylindrical body 4' and the inner surface of the partition plate 32, and the state with the gap 33 being filled with a positive electrode active material 3 is maintained. A guard tube 9' provided with a communicating hole 10 in the bottom end part thereof is arranged in the cylindrical body 4'; a gap 11 is formed between the guard tube 9' and the cylindrical body 4'. The state in which the gap 11 is filled with a negative electrode active material 2 is maintained; and accordingly, the liquid level of the positive electrode active material 3 and the liquid level of the negative electrode active material 2 do not change at charging/ discharging, the high-performance sodium secondary battery 31 can be obtained, without lowering and deteriorating the performance level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sodium secondary battery, and more particularly to a sodium secondary battery having excellent charge / discharge efficiency and a method of manufacturing the same.

[0002]

2. Description of the Related Art First, a sodium secondary battery comprising a sodium-sulfur battery will be described with reference to the drawings. FIG.
In the cylindrical sodium secondary battery 1 shown in FIGS. 3A and 3B, a negative electrode active material 2 made of sodium, a positive electrode active material 3 made of sulfur, a negative electrode active material 2 and a positive electrode active material 3, A conductive electrolyte 5 made of a carbon fiber cloth for impregnating the positive electrode active material 3 and assisting electron conduction of the positive electrode active material 3; a positive electrode active material 3 and a conductive auxiliary material 5
And a positive electrode current collector 6 for electrically connecting the power supply to an external circuit.

In FIGS. 3 (a) and 3 (b), the solid electrolyte 4 is a bottomed cylindrical tube 4 'made of ceramics or glass having conductivity to sodium ions. For example, β-alumina (Na ₂ O · 11Al ₂ O ₃ ) or Mg as a stabilizer
Β ″ -alumina (3Na ₂ O) to which O, Li ₂ O, etc. are added
.16Al ₂ O ₃ ). 3 (a) and 3 (b), the positive electrode current collector 6 is a cylindrical can 6 ', and its material is, for example, stainless steel, Ni alloy, or the like.

In the sodium secondary battery 1, the negative electrode active material 2 is housed in a cylindrical tube 4 ′ of a solid electrolyte 4. The cylindrical tube 4 ′ of the solid electrolyte 4 is connected to the positive electrode current collector 6.
In a cylindrical can 6 '. Further, a conductive auxiliary material 5 made of carbon fiber cloth impregnated with the positive electrode active material 3 (sulfur)
Is disposed between the positive electrode can 6 ′ and the cylindrical tube 4 ′ of the solid electrolyte 4. In this manner, the solid electrolyte 4 is disposed between the negative electrode active material 2 and the positive electrode active material 3, and separates the negative electrode active material 2 from the positive electrode active material 3. That is, the negative electrode active material 2 is stored in the negative electrode active material storage part A in the cylindrical tube 4 ′ made of the solid electrolyte 4, and the positive electrode active material 3 is stored in the positive electrode current collector on the outer peripheral side of the cylindrical tube 4 ′. 6 is housed in a positive electrode active material housing B in a cylindrical can 6 ′.

Further, an insulating ring 7 made of α-alumina or the like is joined to the upper portion of the cylindrical tube 4 ′ of the solid electrolyte 4 by a joining material such as glass solder. The insulating ring 7 is joined to the cylindrical can 6 ′ to seal the negative electrode active material 2 and the positive electrode active material 3. The sealing body 8 is joined to the insulating ring 7 and serves as a negative electrode terminal. Further, a negative electrode current collector 9 is connected to the sealing body 8. The negative electrode current collector 9 electrically connects the negative electrode active material 2 and the sealing member 8 as a negative electrode terminal.

In the negative electrode of the sodium secondary battery 1,
The discharge reaction is as shown in equation (1). That is, the negative electrode active
Sodium (Na) which is substance 2 is sodium ion
(Na ⁺) And electrons (e^-) And divided into sodium ions
(Na⁺) Is conducted in the solid electrolyte 4 and in the positive electrode active material 3.
Into the electron (e^-) Indicates the negative electrode current collector 9 and the sealing body 8
To an external circuit via The discharge reaction at the positive electrode is given by the formula
As shown in (2), the invasion into the positive electrode active material 3
Thorium ion (Na⁺) Reacts with sulfur (S) to produce
Sodium sulfide (Na_TwoS_x).

At the time of charging the sodium secondary battery 1, a reaction reverse to the discharge reaction occurs, and sodium (Na) and sulfur (S) are generated. Usually, sodium polysulfide (Na
Charge until a part of ₂ S _x ) remains. This is because the specific resistance of sodium polysulfide (Na ₂ S _x ) is lower than that of sulfur (S). Therefore, if sodium polysulfide (Na ₂ S _x ) is left, an increase in the resistance of the positive electrode active material is suppressed. Because you can do it.

[0008]

(Equation 1)

[0009]

(Equation 2)

By the way, this kind of sodium secondary battery 1
Then, at the time of discharging and at the time of charging, the liquid level of the active material in the positive electrode and the negative electrode changes. When the liquid level of the positive electrode active material 3 decreases, the contact area between the positive electrode active material 3 and the solid electrolyte 4 decreases, the current density increases, and the performance decreases and deteriorates. Is lower, the contact area between the negative electrode active material 2 and the solid electrolyte 4 is reduced, the current density is also increased, and the performance is deteriorated and deteriorated.

For this reason, as shown in FIG. 4, a safety tube 9 'serving as a cylindrical negative electrode having a communication hole 10 formed at the tip end is disposed in a cylindrical body 4' made of the solid electrolyte 4, and The upper end of the body 4 'is air-tightly fixed to the outer periphery of the safety pipe 9', and the inside of the safety pipe 9 'is evacuated from the upper end of the gap 11 between the cylindrical body 4' and the safety pipe 9 '. The negative electrode active material 2 made of sodium is injected from the injection port 12 and filled, and then the injection port 12 is closed to apply a predetermined gas pressure to the safety pipe 9 ′. The gap 11 between the anode active material 2 and the safety pipe 9 ′ is filled with the negative electrode active material 2 so that the liquid level of the negative electrode active material 2 does not change during charging and discharging, thereby suppressing deterioration and deterioration of performance. Sodium secondary batteries 13 have been developed.

[0012]

However, even with this type of sodium secondary battery 13, performance and deterioration due to a change in the liquid level of the positive electrode active material 3 are inevitable, and further reduction and deterioration of performance are to be suppressed. It was the present situation that was desired. Moreover, on the negative electrode side, the negative electrode active material 2 made of sodium is injected into the inside of the safety tube 9 ′ from the injection port 12 while vacuuming is performed from the upper end of the gap 11 between the solid electrolyte 4 and the safety tube 9 ′. However, the operation of injecting liquid sodium not only requires a great deal of work but also has a problem of lack of safety.

The present invention has been made in view of the above circumstances, and it is possible to easily and safely manufacture a high-performance sodium secondary battery in which deterioration and deterioration of performance are suppressed, and this sodium secondary battery. It is an object of the present invention to provide a method for manufacturing a simple sodium secondary battery.

[0014]

According to a first aspect of the present invention, there is provided a sodium secondary battery according to the first aspect, wherein a cylindrical body made of a solid electrolyte is disposed in a bottomed cylindrical container. A negative electrode active material made of sodium is stored in the body,
A sodium secondary battery containing a cathode active material between the container and the inside of the cylindrical tube, wherein the cathode active material is formed between the container containing the cathode active material and the cylindrical body. In the storage part, a cylindrical partition plate is provided, with an upper end connected to the cylindrical body and a lower end provided with a gap, and the upper part of the gap between the partition plate and the cylindrical body is sealed. The gap between the partition plate and the cylindrical body is filled with the positive electrode active material, and the inside of the positive electrode active material storage is pressurized.

That is, a cylindrical partition plate is provided in the positive electrode active material storage portion on the outer peripheral side of the cylindrical body, and the gap between the outer peripheral surface of the cylindrical body and the inner peripheral surface of the partition plate is filled with the positive electrode active material. By maintaining this, it is possible to eliminate a change in the liquid level of the positive electrode active material during charge and discharge, whereby a high-performance sodium secondary battery with reduced performance and deterioration can be obtained.

According to a second aspect of the present invention, there is provided the sodium secondary battery according to the first aspect, wherein a safety tube having a communication hole formed at a lower end portion is provided in the cylindrical body.
The upper end of the cylindrical body is connected to the outer peripheral surface of the safety pipe,
An upper portion of a gap between the safety pipe and the cylindrical body is sealed, a gap between the safety pipe and the cylindrical body is filled with the negative electrode active material, and the inside of the safety pipe is pressurized.

As described above, the safety pipe having the communication hole formed at the lower end is provided in the cylindrical body, and the gap between the safety pipe and the cylindrical body is maintained in a state filled with the negative electrode active material. A change in the liquid level of the negative electrode active material during charge and discharge can be prevented, whereby a high-performance sodium secondary battery with further reduced and degraded performance can be obtained.

According to a third aspect of the present invention, there is provided a method for manufacturing a sodium secondary battery, wherein a cylindrical body made of a solid electrolyte is provided in a bottomed cylindrical container, and a negative electrode active material made of sodium is stored in the cylindrical body. Between the vessel and the cylindrical tube,
A method for manufacturing a sodium secondary battery containing a positive electrode active material, wherein a predetermined amount of the negative electrode active material and a gas are injected into a safety tube formed into a cylindrical shape having a smaller diameter than the inner diameter of the cylindrical body. Then, the inside is pressurized and sealed, and a communication hole is opened in a lower end portion of the safety tube in a state where the negative electrode active material is solidified by cooling the safety tube into which the negative electrode active material has been injected. By inserting the safety tube into the cylinder and connecting the upper end of the cylinder to the safety tube, the upper part of the gap between the safety tube and the cylinder is sealed,
Thereafter, the gap between the cylindrical body and the safety pipe is evacuated from the upper end side and the temperature of the safety pipe is raised to melt the negative electrode active material, thereby allowing the cylindrical body and the safety pipe to pass through the communication hole. It is characterized by filling gaps.

That is, after the sodium injected into the safety pipe is cooled and solidified, a communication hole at the lower end is formed, inserted into the cylinder, the upper end of the cylinder is sealed, and the gap is evacuated. Thereafter, by raising the temperature to liquefy the sodium, it is possible to manufacture a sodium secondary battery in which the gap is filled with sodium very safely and easily and the liquid level of the negative electrode active material is prevented.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sodium secondary battery according to an embodiment of the present invention will be described below with reference to the drawings. In addition, the same reference numerals are given to the above-mentioned conventional structure parts, and the description is omitted. In FIG. 1, reference numeral 31 denotes a sodium secondary battery including a sodium-sulfur battery. In the sodium secondary battery 31, a partition plate 32 formed in a cylindrical shape is provided in a positive electrode active material container B filled with the positive electrode active material 3. The upper end of the partition plate 32 is airtightly connected to a cylindrical body 4 ′ made of the solid electrolyte 4, and the lower end of the partition plate 32 is spaced from the bottom surface of the cylindrical can 6 ′ made of the positive electrode current collector 6. Supported.

In the gap 33 between the cylindrical body 4 'and the partition plate 32, the positive electrode active material 3 is injected into the positive electrode active material accommodating portion B while evacuating the upper end thereof.
The positive electrode active material 3 is filled. Further, a gas is filled into the positive electrode active material container B filled with the positive electrode active material 3 from a gas supply port (not shown) at a predetermined pressure, and the cylindrical body 4 ′ is formed.
The filling state of the positive electrode active material 3 into the gap 33 between the partitioning plate 32 and the positive electrode active material 3 is maintained.

The sodium secondary battery 3 having the above structure
According to 1, not only is the gap 11 between the inner peripheral surface of the cylindrical body 4 ′ and the outer peripheral surface of the safety tube 9 ′ maintained filled with the negative electrode active material 2, but also on the outer peripheral side of the cylindrical body 4 ′. A cylindrical partition plate 32 is provided in the positive electrode active material storage section B, and a cylindrical body 4 'is provided.
The gap 33 between the outer peripheral surface of the anode and the inner peripheral surface of the partition plate 32 is maintained to be filled with the positive electrode active material 3, and changes in the liquid levels of the negative electrode active material 2 and the positive electrode active material 3 during charging and discharging, respectively. Thus, a high-performance sodium secondary battery 31 with further reduced and degraded performance can be obtained.

Next, the case of manufacturing the negative electrode side in the sodium secondary battery 31 will be described. (1) First, a predetermined amount of liquid sodium, which is the negative electrode active material 2, is injected from the upper hole 41 of the cylindrical safety tube 9 'made of stainless steel (see FIG. 2A). (2) When a predetermined amount of sodium is injected, gas is injected into the space above the safety pipe 9 'to seal the hole 41 (see FIG. 2 (b)).

(3) Next, the injected sodium is solidified by cooling the safety pipe 9 'into which the sodium has been injected. (4) In this state, the communication hole 1 is provided at the lower end of the safety pipe 9 '.
0 is formed (see FIG. 2C). Here, sodium in the safety pipe 9 ′ is cooled and solidified, so that sodium does not flow out from the communication hole 10.

(5) Thereafter, the safety tube 9 'is inserted into the cylindrical body 4' made of the solid electrolyte 4 from above, and
The upper end of the cylindrical body 4 'and the outer circumference at the upper end of the safety pipe 9' are closed (see FIG. 2 (d)), and furthermore, the gap between the inner circumferential surface of the cylindrical body 4 'and the outer circumferential face of the safety pipe 9' is closed. 11 is evacuated. (6) Then, when the temperature is raised in the state where the negative electrode is formed in the cylindrical body 4 ′ to melt the sodium in the safety tube 9 ′, the liquefied sodium is evacuated from the communication hole 10 through the communication hole 10. Clearance 1 between drawn cylindrical body 4 'and safety pipe 9'
It is drawn into 1 and filled.

As described above, according to the above-described manufacturing method, the sodium injected into the safety pipe 9 'is cooled and solidified, and then the communication hole 10 at the lower end is formed and inserted into the cylindrical body 4'. The gap 11 is evacuated by sealing the upper end of the cylindrical body 4 ′ and then the temperature is raised to liquefy the sodium, so that the gap 11 is filled with sodium very safely and easily. The sodium secondary battery 31 in which the liquid level is prevented from lowering can be manufactured.

In the above example, the communication hole 10 is formed at the lower end of the safety pipe 9 '. However, this communication hole 10 is formed in advance, closed with, for example, a screw or the like. The communication hole 10 may be opened by removing the screw.

[0028]

As described above, according to the sodium secondary battery of the present invention, the following effects can be obtained.
According to the sodium secondary battery of the first aspect, a cylindrical partition plate is provided in the positive electrode active material storage portion on the outer peripheral side of the cylindrical body, and the positive electrode is inserted into the gap between the outer peripheral surface of the cylindrical body and the inner peripheral surface of the partition plate. By maintaining the active material in a full state, it is possible to eliminate a change in the liquid level of the positive electrode active material during charge and discharge, thereby providing a high-performance sodium secondary battery with reduced performance and deterioration. be able to.

According to the sodium secondary battery of the second aspect, the safety tube having the communication hole formed at the lower end is provided in the cylindrical body, and the gap between the safety tube and the cylindrical body is filled with the negative electrode active material. Is maintained in the state, the liquid level of the negative electrode active material at the time of charge and discharge can be prevented from being changed, thereby making it possible to obtain a high-performance sodium secondary battery with further suppressed deterioration and deterioration. it can.

According to the sodium secondary battery according to the third aspect, after cooling and solidifying the sodium injected into the safety tube, a communication hole at the lower end is formed and inserted into the cylinder to insert the upper end of the cylinder. The gap is closed and the gap is evacuated, and then the temperature is raised to liquefy the sodium, so that the gap is filled with sodium very safely and easily to prevent the liquid level of the negative electrode active material from being lowered. A secondary battery can be manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view of a sodium secondary battery illustrating a structure of a sodium secondary battery according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a negative electrode current collector illustrating a method for manufacturing a sodium secondary battery according to an embodiment of the present invention.

FIG. 3 is a sectional view of a sodium secondary battery illustrating a basic structure of the sodium secondary battery.

FIG. 4 is a cross-sectional view of a sodium secondary battery illustrating a conventional technology of the sodium secondary battery.

[Explanation of symbols]

 Reference Signs List 2 negative electrode active material 3 positive electrode active material 4 solid electrolyte 4 'cylindrical body 6' container 9 'safety tube 10 communication hole 11, 33 gap 31 sodium secondary battery 32 partition plate B positive electrode active material storage

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H029 AJ04 AJ14 AK05 AL13 AM15 BJ02 BJ16 BJ22 CJ03 CJ13 CJ28 DJ02 DJ04 HJ12

Claims (3)

[Claims] A cylindrical body made of a solid electrolyte is provided in a bottomed cylindrical container, a negative electrode active material made of sodium is stored in the cylindrical body, and between the container and the inside of the cylindrical tube, A sodium secondary battery in which a positive electrode active material is stored, wherein the positive electrode active material storage portion formed between the container in which the positive electrode active material is stored and the cylindrical body has a cylindrical shape. A partition plate, the upper end of which is connected to the cylindrical body and is provided with a gap at the lower end, the upper part of the gap between the partition plate and the cylindrical body is sealed, and the partition plate and the cylindrical body A sodium secondary battery, wherein a gap is filled with the positive electrode active material, and the inside of the positive electrode active material container is pressurized. 2. A safety pipe having a communication hole formed at a lower end thereof is provided in the cylindrical body, and an upper end of the cylindrical body is connected to an outer peripheral surface of the safety pipe. 2. The sodium secondary according to claim 1, wherein an upper part of a gap between the safety pipe and the cylindrical body is sealed, a gap between the safety pipe and the cylindrical body is filled with the negative electrode active material, and the inside of the safety pipe is pressurized. battery. 3. A cylindrical body made of a solid electrolyte is disposed in a bottomed cylindrical container, a negative electrode active material made of sodium is stored in the cylindrical body, and between the container and the inside of the cylindrical tube, A method for manufacturing a sodium secondary battery containing a positive electrode active material, wherein a predetermined amount of the negative electrode active material and a gas are injected into a safety tube formed in a cylindrical shape having a smaller diameter than the inner diameter of the cylindrical body. Then, the inside of the safety tube into which the negative electrode active material has been injected is cooled and the safety tube into which the negative electrode active material has been injected is cooled to form a communication hole in a lower end portion of the safety tube in a state where the negative electrode active material is solidified. By inserting the safety pipe into the cylinder and connecting the upper end of the cylinder to the safety pipe, the upper part of the gap between the safety pipe and the cylinder is sealed, and then the cylinder and the safety Vacuum the gap with the tube from the top The negative active method for producing a sodium secondary battery, characterized in that to fill the gap material from the communication hole by melting and the safety tube and the cylinder by raising the temperature of said safety tube with.