JPS61264659A - Sodium-sulfur battery cathode case and its manufacture - Google Patents

Abstract

PURPOSE:To enhance anti-corrosion characteristic by providing a particular alloy layer sprayed at a low pressure to the surface of basic material. CONSTITUTION:A layer consisting of Cr, Cr-Fe or TiN sprayed at a low pressure is formed on the surface of basis material. The plasma is generated by supplying Argon gas into the arc 27 form the operation gas supply device 17 and a voltage is also applied across a nozzle 8 and a cooling base material 25. Thereby, the plasma jet 29 is sprayed toward the surface of cooling base material from the nozzle 8. Under this condition, the power of a raw material of the jar is supplied to the nozzle 8 from the supply hole 9. Particles of powder of jar material sprayed into the nozzle 8 becomes fine melted drops by the heat of plasma and it is accumulated on the surface of cooling base material 25 and the accumulated drops are condensed and thereby a cylindrical mold 31 is formed at the surface of cooling base material. Since the cathode jar is formed by plasma spraying within a low pressure ambience, comparatively economical material having excellent anti-corrosion characteristic can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an anode container constituting a sodium-sulfur battery and a method for manufacturing the same.

(Prior technology) Sodium-sulfur batteries use molten sodium as the cathode active material.
Molten sulfur and sodium polysulfide are used as the anode active materials, and ceramics or glass that transmit sodium ions are used as the electrolyte. Sodium-sulfur batteries typically operate at 300-350°C and have high energy density. Currently, development is progressing in various countries as a high-performance secondary battery for use in power load adjustment or as a power source for electric vehicles, but a major development challenge lies in the need for an anode container that exhibits sufficient corrosion resistance against sodium polysulfide. It has become a bottleneck.

That is, sodium polysulfide has a strong corrosive effect and corrodes an anode container made of stainless steel or the like, producing sulfides. As corrosion progresses, sulfur in the anode active material is consumed due to sulfidation, reducing the amount of sulfur that can act as the anode active material. This reduces battery capacity and shortens battery life. Additionally, if localized corrosion occurs, holes may form in the anode container, causing the anode active material to leak out and shorten the life of the battery. Therefore, the anode container must exhibit excellent corrosion resistance to the anode active material, as well as sufficient mechanical strength, workability, and good 71! during anode current collection. Air conductivity is also required. Currently, materials such as No, Cr, 0r-Fe, chromized steel, or TiN are being used as materials that meet these requirements.

(Problems to be Solved by the Invention) Among these materials, No has good overall corrosion resistance, but the form of corrosion tends to be pitting corrosion, and it is also expensive, while Cr-Fe has a higher corrosion resistance. That is, as the Cr content increases, processing becomes more difficult. Chromizing steel has a chromium-rich layer of no more than 200 μm, and the chromium concentration of the chromium-rich layer is at most 40% or less, so its corrosion resistance is somewhat inferior. Coatings made of Cr and TiN tend to cause pinhole cracks in the coating layer during manufacture, and often contain particles such as oxides, making it difficult to obtain a layer of uniform and sufficient thickness.

Therefore, the present invention aims to develop a Cr material with sufficient thickness to exhibit corrosion resistance against sodium polysulfide in a sodium-sulfur battery.
, it is an object of the present invention to provide a method by which an anode container having a Cr-Fe or TtN layer can be manufactured without producing defects such as pinholes.

(Means for Solving the Problems) The sodium monosulfur battery anode container of the present invention has a low-pressure sprayed layer of Or, Cr--Fe or TiN on the surface of the base.

Further, in the method for manufacturing a sodium monosulfur battery anode container of the present invention, an anode container raw material made of Cr, Or-Fe, or TiN is plasma sprayed onto the surface of a substrate in a low-pressure atmosphere.

When the anode container raw material is Cr-Fe, the Cr content is preferably 80 to 90X from the viewpoint of corrosion resistance.

In order to maintain a low-pressure atmosphere, plasma spraying is performed in a closed container, and the pressure inside the container is 100 Torr (1,
333 x 104 Pa) or less, and the inside of the closed container may be filled with an inert gas such as argon.

The substrate may be a box-shaped or cylindrical container made of, but not limited to, common stainless steel such as 5O5304. Anode container raw materials are thermally sprayed onto the inner surfaces of these containers. In addition, the raw material is plasma sprayed onto the outer peripheral surface of a cylindrical base made of easily meltable metal such as copper. Then, the substrate may be removed by corrosion and dissolution with acid to obtain a cylindrical anode container.

The thickness of the Cr-Fe layer or the container wall formed in this way is, for example, 500 to 1000 μm.

(Function) In this invention, since the anode container raw material is plasma sprayed in a low-pressure atmosphere, the molten particles of the raw material are not oxidized by the atmosphere and are deposited on the surface of the substrate and hardened by WI. Further, since the molten particles of the raw material are accelerated by the high-speed jet, they collide with the substrate surface or solidification surface at high speed. Therefore, an extremely dense and thick laminated layer is formed on the substrate surface without producing pinholes or oxide films.

(Example) FIG. 1 is a drawing schematically showing the outline of a plasma spraying apparatus for manufacturing a cylindrical anode container according to the present invention.

As shown in FIG. 1, the plasma spraying apparatus includes an atmosphere chamber 1, which is maintained at a low pressure by a vacuum pump 2. As shown in FIG.

A plasma gun 5 is arranged in the atmosphere chamber l, and the plasma gun 5 is moved back and forth and left and right by a drive device 11.
It also swings around the horizontal axis. The plasma gun 5 consists of a tungsten electrode 6 and a nozzle 8 disposed directly below the tungsten electrode 6. Electrode 6 and nozzle 8 are connected to a negative electrode and an anode of plasma main power source 13, respectively. The nozzle 8 of the plasma gun 5 has an operating gas supply device! 7 is connected. Further, a raw material supply hole 9 is provided in the nozzle 8 of the plasma gun 5, and a raw material supply device 19 is connected to this. In addition, a workpiece holding device 2 is provided in the atmosphere chamber l.
1 is arranged, and the workpiece holding device 21 is connected to the rotating device 2.
3 around the horizontal axis. Workpiece holding bag fi
A cylindrical cooling base 25 is attached to 21 . The cooling substrate 25 is cooled by circulating cooling water from a substrate cooling device 26 .

In the apparatus configured as shown in L, a cylindrical copper cooling substrate 25 is attached to a cooling substrate holding device 21 and rotated at a low speed by a workpiece rotation device 23. The inside of the atmosphere chamber 1 is heated to 100 Torr (1,333×10
'Pa) or less, and a required voltage is applied between the electrode 6 and the nozzle 8 to generate an arc 27.

Argon gas is supplied from the operating gas supply device 17 into the arc 27 to generate plasma. Furthermore, when a voltage is applied between the nozzle 8 and the cooling base 25, the plasma jet 2
9 is injected from the nozzle 8 toward the surface of the cooled substrate.

In this state, the container raw material powder is supplied to the nozzle 8 from the raw material supply hole 9.

The powder particles of the container raw material ejected into the nozzle 8 turn into fine droplets due to the heat of the plasma and are deposited on the surface of the cooling base 25 . The laminated droplets solidify, and a cylindrical molded body 31 is formed on the surface of the cooled base.

When the molded body 31 of the required thickness is obtained, it is cooled to near room temperature and taken out from the atmosphere chamber 1, and the molded body 31 integrated with the cooling base 25 is immersed in nitric acid to corrode and dissolve the copper and remove it. do. As a result, the cooling base 25 disappears and a cylindrical anode container is obtained.

Here, product examples will be explained.

Material 80% Cr-Fe Particle size 325 mesh (44μ or less) Supply amount 100
g/win Output 80 kW Operating gas Ar-He mixed gas Atmospheric pressure 20 Torr Plasma gun movement speed 150+u+/s Product example Product Box-shaped anode container cooling base 5OS304 Box-shaped container thickness 11 lining product example Product Cylindrical Anode container 40 layers ■φX400+wmQX1mst cooling base Water cooling copper tube 40 porcelain φX40hmi100 rp■ After thermal spraying, the anode containers manufactured by corrosion dissolution with nitric acid did not have any defects such as pinholes.

(Effect of the invention) In this invention, the anode container is manufactured by plasma spraying in a low pressure atmosphere, and does not require machining or welding.
Therefore, even if it is difficult to process, it is possible to use a material that has excellent corrosion resistance and is relatively inexpensive. In addition, defects such as pinholes do not occur in the container during manufacturing, making it possible to provide a sodium-sulfur battery anode container with excellent corrosion resistance.

[Brief explanation of the drawing]

FIG. 1 is a drawing schematically showing the outline of a plasma spraying apparatus for manufacturing a cylindrical anode container according to the present invention. 1... Atmosphere chamber, 2... Vacuum pump, 5... Plasma gun, 6... Electrode, 8... Nozzle, 11...
・Plasma gun, 13...Plasma main power supply, 17...
- Operating gas supply device, 19... Raw material supply device, 21.
...Workpiece holding device. 23... Workpiece rotation device, 25... Cooling base, 2B
... Substrate cooling device, 27 ... Arc, 29 ... Plasma jet, 31 ... Anode container.

Claims (2)

[Claims] (1) A sodium monosulfur battery anode container characterized by having a low-pressure sprayed layer of Cr, Cr-Fe, or TiN on the surface of the base. (2) A method for producing an anode container for a sodium-sulfur battery, which comprises plasma spraying an anode container raw material made of Cr, Cr-Fe, or TiN onto the surface of a substrate in a low-pressure atmosphere.