JP2815531B2 - Method for producing anode container for sodium-sulfur battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an anode container for a sodium-sulfur battery and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, in an anode container of a sodium-sulfur battery, in order to enhance corrosion resistance to sodium polysulfide, as shown in, for example, Japanese Patent Application Laid-Open No. 61-264659, a corrosion-resistant coating is formed by plasma spraying in a low-pressure atmosphere. Methods of forming have been proposed. This method is convenient when a film is formed on the outer peripheral surface of a cylindrical container body, or in the case of free standing, that is, when a material is dissolved after thermal spraying to take out a film and a substrate is manufactured using the film. is there.

However, there is a problem that productivity is low for continuous industrial production. Further, a method of forming a coating on the inner wall peripheral surface of the anode container body by plasma spraying at atmospheric pressure has been proposed by the present applicant. In the method of forming a film on the inner peripheral surface of the anode container by this plasma spraying, the spraying portion of the spray gun is inserted in the axial direction while rotating the cylindrical anode container, and the cylindrical anode container body is rotated. By spirally rotating the inner wall, a uniform film is formed on the inner wall.

[0004]

However, when a large number of anode containers are industrially and continuously plasma-sprayed industrially by such film formation by thermal spraying, the spray gun reciprocates in the anode container. When the powder is continuously ejected without stopping the supply of the powder and sprayed to a predetermined thickness when moving from one end to the other end, and when the spray gun is taken out of the container, It was quickly pulled up and ready for thermal spraying of the next container. The reason why the powder is continuously ejected from the spray gun is to perform stable plasma spraying. The reason why plasma spraying is not performed to a predetermined thickness during reciprocation is to form a uniform sprayed coating in the thickness direction.

[0005] However, when a large number of cylindrical anode containers formed continuously and industrially in the air by plasma spraying in the air by this method are used as anode containers for sodium-sulfur batteries, the initial stage is relatively low. The battery capacity decreased stepwise at the stage, and thereafter, the battery capacity tended to decrease gradually. As a result of various investigations for the cause, the inventor has found that there is a cause in the coating of the anode container.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. The flame from the spraying section is continuous and the powder is continuously supplied, and the spray gun is provided inside the rotating cylindrical anode container. It is an object of the present invention to provide a method for manufacturing a sodium-sulfur battery in which a uniform high-quality film is formed on the inner peripheral wall of an anode container by moving in one direction and then continuously in the opposite direction.

Another object of the present invention is to provide a method of manufacturing an anode container for a sodium-sulfur battery with high productivity without a sharp decrease in battery capacity.

[0008]

In order to achieve the above object, a method for producing an anode container for a sodium-sulfur battery according to the present invention comprises the steps of: rotating a cylindrical metal anode container while coating the inner wall of the anode container; In the method of forming, the spraying part is moved in the axial direction into the anode container from one end to the other end of the anode container, a thin spiral sprayed layer on the inner wall of the anode container. After forming and spraying the thermal spraying part through the other end, then the thermal spraying part in the axial direction opposite to the axial direction in the anode container from the other end to one end of the anode container Is moved at a speed lower than the moving speed from the one end to the other end to form a uniform film on the inner wall of the anode container.

[0009]

According to the method for manufacturing the anode container for a sodium-sulfur battery constructed as described above, a uniform film is formed on the inner peripheral wall of the cylindrical anode container and the inner peripheral wall of each anode container is formed on the inner peripheral wall of each anode container. A film can be formed quickly, and a film can be formed on the inner peripheral wall of a large number of anode containers in a short time.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. One embodiment of a method for manufacturing an anode container for a sodium-sulfur battery embodying the present invention is shown in FIGS. In the manufacturing method of this embodiment, FIGS.
As shown in FIG. 1, chromium (Cr) -silicon (Si) -iron is applied to the inner peripheral surface of a cylindrical container body 2 made of a non-ferrous metal material such as aluminum (Al) or an Al alloy using a thermal spray gun 1. A powder material 3 made of an (Fe) alloy is plasma sprayed in the air to form a corrosion resistant film 4.

In the plasma spraying, an argon gas is used as a primary gas, and a hydrogen gas is added as a secondary gas. And the supply amount of this gas is 2 g of argon gas.
The hydrogen gas is set in the range of 0.2 to 3.0 liter / min, and the current is set in the range of 150 to 280 A. The supply amount of the powder material 3 is 10 to 10
Set within the range of 0 g / min.

Here, the step of forming the coating 4 on the inner peripheral wall of the anode container 2 with the powder ejected from the thermal spray gun 1 will be described in detail. (1) First, the anode container 2 is rotated at a constant speed, for example, at 300 rpm, and the spraying gun 1 is moved downward from above at a speed of, for example, 50 to 50 rpm.
It moves down at a constant speed of 400 mm / sec. Then, as shown in FIG. 1A, a thin first sprayed layer 10 sprayed on the inner wall of the anode container 2 is formed in a spiral shape.

(2) Next, when the spraying gun 1 reaches the position shown in FIG. 1A, the spraying gun 1 is stopped at that position.
Stop for 10 seconds. The spraying of the powder material 3 to be sprayed is continuously performed without stopping. This is because the spray material sprayed from the spray gun 1 is supplied stably and a uniform spray layer having a constant thickness is always formed on the inner wall surface of the anode container 2.

(3) Next, the spray gun 1 is placed inside the anode container 2 while the anode container 2 is continuously rotated at a constant speed as described above.
The rising movement in the opposite direction to the range of the a downward movement slower than when for example 5 to 20 mm / sec upward as shown in FIG. 1B. Then, a uniform coating 4 is formed on the inner peripheral wall of the anode container 2 as shown in FIG. 1B. The thickness of this film is, for example, 20 to 100 μm.

As described above, according to the manufacturing method of this embodiment, since the powder material 3 is plasma-sprayed on the inner peripheral wall surface of the anode container 2 in the air, it is different from the conventional method of plasma spraying under a low-pressure atmosphere. However, the plasma arc does not become extremely long. Therefore, even when the inner diameter of the anode container 2 is small,
The spray distance can be secured, and the corrosion-resistant coating 4 can be easily formed on the inner peripheral surface of the anode container 2 without melting and cutting the anode container 2.

The anode container 2 has an outer diameter of 50.
With a length of up to 180 mm, a length of 200 to 500 mm can be applied. Then, the anode container 2 is preheated at 200 ° C. or higher, and plasma spraying is performed while rotating the anode container 2 at 100 to 600 rpm.
The corrosion-resistant film 4 having a thickness of 200 μm can be formed. The spraying start temperature is, for example, 150 ° C. or more, and the powder supply amount is 10 to 80 g / min.

By the above-described method, a film made of a Cr-Si-Fe alloy is formed on the inner peripheral wall of the anode container body as shown in the schematic diagram of FIG. In FIG. 2, first, a spiral first sprayed layer 31 formed when the spray gun 1 descends is formed thin on the surface of the anode container 2. This is because the thermal spray gun 1 is formed by a downward movement at a high speed and is formed at a predetermined interval and is thin. Further, since the spray gun 1 moves at a low speed when moving upward, the second spray layer 32 which covers the first spray layer 31 and is thick on the inner wall of the anode container 2 is formed with a uniform thickness. Thereby, the surface of the second thermal spray layer 32 becomes uniform.

On the other hand, FIG. 3 shows a comparative example which has been conventionally implemented by the inventor. This comparative example is not known. In this comparative example, when a large number of anode containers are industrially and continuously plasma-sprayed, the sprayed powder and the primary gas,
The secondary gas is continuously injected, maintains a stable injection state, and continuously injects each container. At this time, the thermal spray gun is inserted from the upper part of the anode container, descends while forming a film in a single operation, and when it reaches the lower part, it is quickly returned to the upper part to prepare for thermal spraying of the next container. At the time of this return, the deposit of the powder material is spirally formed on the surface of the film formed. That is, a thick first sprayed layer 21 is formed on the surface of the anode container when descending, and a thin second sprayed layer is formed on the surface of the first sprayed layer 21 when rising at a high speed when returning. 22 are spirally formed at predetermined intervals. For this reason, on the surface of the film formed on the surface of the anode container 2, a non-uniform sprayed layer locally heated with a large number of undissolved particles adhered by the second sprayed layer 22 is formed. When a sodium-sulfur battery is assembled using this anode container, a large number of undissolved particles form sulfides from the film surface. This is because the battery capacity decreases stepwise in the initial stage of operation of this battery. Becomes Therefore, film formation by the method of the comparative example is not necessarily appropriate film formation.

Also, as described above, the inner peripheral surface of the anode container 2
And a powder 3 made of a Cr—Si—Fe alloy in air
In the case of plasma spraying, Si is preferentially oxidized first
Silicon dioxide (SiO_Two ) Is formed and then Cr
Is oxidized to chromium oxide (Cr _Two O_Three ) Is formed.
The base of the Cr-Fe alloy is almost oxidized.
Therefore, the porosity is 1 to 5% and the surface roughness is Ra (average).
Roughness, JIS B0601) 8 to 15 μm dense corrosion-resistant film
And the Vickers hardness of the base portion is Hv: 300-
500.

Next, FIG. 6 shows an example of a sodium-sulfur battery using the anode container formed by using this embodiment.
As shown in FIGS. 1 and 6, the anode container 1 is formed in a cylindrical shape from a metal material such as aluminum or an aluminum alloy, and a bottom plate 2 is fitted and fixed to an opening at a lower end thereof. A pair of upper and lower constrictions 3 and 4 are formed on the outer periphery of the anode container 1 at predetermined intervals in the longitudinal direction.
4 absorbs and reduces the expansion and contraction of the anode container 1 due to the thermal change. In addition, the lower constricted part 4 is provided above the lower part, avoiding sodium polysulfide (Na ₂ S _X ) as an active material accumulated at the lower end. The corrosion-resistant coating 5 is formed by spraying on the inner peripheral surface of the anode container 1, and the corrosion-resistant coating 5 prevents corrosion of the anode container 1.

The support fitting 6 is fitted and fixed to the upper end of the anode container 1 at the upper end thereof, and an insulating ring 7 made of alpha alumina is fixed to the upper surface thereof. A cylindrical fixed electrolyte tube 8 made of a ceramic material such as beta-alumina is fixedly joined to a lower end circumference of the insulating ring 7, and a cathode chamber R 1 is defined inside the solid electrolyte tube 8, and is formed outside the solid electrolyte tube 8. Has an anode chamber R2 formed therein.

The cartridge 9 is disposed in the cathode chamber R1, and contains sodium Na as a cathode active material. The small hole 10 is provided at the bottom of the cartridge 9, and the sodium Na in the cartridge 9 is supplied to the gap between the cartridge 9 and the solid electrolyte tube 8 through the small hole 10. Nitrogen gas is filled with an inert gas G such as argon gas in the upper space of the cartridge 9 at a predetermined pressure, and the inert gas G pressurizes sodium Na in the cartridge 9 in a direction of flowing out of the small holes 10. ing. The anode conductive material 11 made of a carbon mat or the like is accommodated in the anode chamber R2, and the anode conductive material 11 is impregnated with sulfur S as an anode active material.

The cathode lid 12 is joined and fixed on the insulating ring 7 and has a central disk portion 13 and a cylindrical portion 14 provided on the outer periphery of the disk portion 13. The lower end of the cylindrical portion 14 of the cathode lid 12 is connected to the sodium Na supplied to the gap between the cartridge 9 and the solid electrolyte tube 8.
, And current collection on the cathode side is performed. The safety tube 15 having a cylindrical shape with a bottom is provided in the gap between the cartridge 9 and the solid electrolyte tube 8 in the cartridge 9 and the solid electrolyte tube 8.
Are formed at a predetermined interval from each other, and are formed of a corrosion-resistant metal material such as aluminum or stainless steel. At the time of discharge, the small holes 1 of the cartridge 9
After the sodium Na supplied from 0 is moved upward in the gap between the safety tube 15 and the cartridge 9,
It moves over the upper end of the safety pipe 15 and moves downward in the gap between the safety pipe 15 and the solid electrolyte pipe 8.

(Experiment 1) In Experiment 1, the sodium-
The relationship between the number of charge / discharge of a sulfur battery and the internal resistance of the battery was examined. FIG. 4 shows the results. In Experiment 1, the temperature during operation was 310 ° C. In FIG. 4, it was found that the internal resistance of the battery in the example of the present invention hardly changed until the number of charge / discharge cycles was large, and was lower than that in the comparative example.

In the comparative example, it is presumed that the cause is contact between the anode conductive material and the sprayed coating or sulfuration of undissolved particles. (Experiment 2) In Experiment 2, the relationship between the number of charge / discharge cycles of the sodium-sulfur battery and the battery capacity was tested. The result is shown in FIG.

In the embodiment of the present invention, even if the number of charge / discharge cycles is large, the decrease in the battery capacity is not so large. On the other hand, in the comparative example, it was found that when the number of charge / discharge cycles reaches a predetermined number, the battery capacity sharply decreases. This is probably because undissolved particles formed on the outermost surface portion of the film formed on the surface of the above-mentioned anode container are sulfided to enter sodium polysulfide and cause capacity deterioration. It is also considered that undissolved particles easily react with sodium polysulfide.

[0027]

As described above, according to the method for manufacturing an anode container for a sodium-sulfur battery of the present invention, a film having excellent corrosion resistance can be uniformly formed on the inner peripheral surface of the anode body. There is an effect that the peel resistance of the film is good. According to the sodium-sulfur battery using the anode container according to this manufacturing method, an increase in internal resistance of the battery is suppressed, and further, there is an effect that a decrease in battery capacity can be reduced even if charge / discharge cycles are repeated.

According to the method for manufacturing an anode container for a sodium-sulfur battery of the present invention, a corrosion-resistant film can be formed on the inner peripheral wall of a cylindrical anode container at a high speed. This has the effect of improving productivity and reducing costs.

[Brief description of the drawings]

FIG. 1 is a process diagram showing one embodiment of a method for manufacturing a sodium-sulfur battery of the present invention.

FIG. 2 is a schematic enlarged sectional view showing a film formation state according to an example of the present invention.

FIG. 3 is a schematic enlarged sectional view showing a film formation state according to a comparative example.

FIG. 4 is a characteristic diagram in which the relationship between the charge / discharge cycle and the internal resistance of the battery according to the example of the present invention is compared between the example of the present invention and a comparative example.

FIG. 5 is a characteristic diagram in which a relationship between a charge / discharge cycle and a battery capacity is compared with an example of the present invention and a comparative example.

FIG. 6 is a schematic sectional view showing one embodiment of a sodium-sulfur battery using the anode container manufactured according to the embodiment of the present invention.

[Explanation of symbols]

 2 Anode container 31 Thermal spray layer 32 Thermal spray layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01M 10/39 H01M 10/38

Claims (2)

(57) [Claims] 1. A method for forming a film on the inner wall of an anode container while rotating a cylindrical metal anode container, wherein the anode container extends from one end to the other end of the anode container. The spraying part is moved in the axial direction inside, a spiral sprayed layer is formed thinly on the inner wall of the anode container, and after the spraying part passes the other end, then the other side of the anode container In the anode container from one end to one end, the spraying jet is moved in a direction opposite to the axial direction at a speed lower than the movement speed from the one end to the other end. A method for producing an anode container for a sodium-sulfur battery, wherein a film is uniformly formed on an inner wall. 2. Spraying the sprayed portion from above by 50 to 4
After moving down at a constant speed of 00 mm / sec to form a helical sprayed coating on the inner wall of the anode container, it moves upward from below in a range of 5 to 20 mm / sec at a lower speed than at the time of the downward movement. The method for producing an anode container for a sodium-sulfur battery according to claim 1, wherein a uniform coating is formed on the inner peripheral wall of the anode container.