JPH04206147A - Protective container for sodium-sulfur battery - Google Patents

Abstract

PURPOSE:To improve corrosion resistance and volumetric efficiency by forming a container body in a cylindrical having a bottom of metal which has Fe as its main component and contains Ni and Cr. CONSTITUTION:A container body 2 for a sodium-sulfur battery 1, which uses sodium as negative electrode active material and uses sulfur as positive electrode active material, is constituted of a cylindrical shape having its bottom made of metal which has Fe as its main component and contains Ni and Cr. Ni improves corrosion resistance against sodium of the negative electrode active material, and Cr improves corrosion resistance against sulfur and sodium polysulfide of the positive electrode active material. The composition is desirable to contain Ni or 3weight% or more and Cr of 10weight% or more against Fe. Thereby, the corrosion resistance can be excellent, and short circuit troubles caused by leakage can be prevented, and the body 2 can be also thinned and downsized.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a protective container for a sodium-sulfur battery that can effectively prevent short circuits, ground faults, etc. caused by leakage of active materials such as sodium and sulfur. It is something.

(Prior art) Multiple sodium-sulfur batteries using sodium as the negative electrode active material and sulfur as the positive electrode active material are connected in a storage case as sealed high-temperature secondary batteries, and are operated at a high temperature of 300 to 350"C. However, if the active material leaks for some reason, short circuits may occur due to electrical continuity between the cells, or ground faults may occur due to electrical continuity between the cells and the storage case, resulting in battery damage. There was a problem that the driving ability of the driver was reduced.

Therefore, the applicant installed a support insulator having a recessed part inside the storage case, as seen in Japanese Patent Application Laid-open No. 2-94355, and installed a battery support tube upright on top of the support insulator to prevent leaked substances. We have previously proposed an insulated support tube structure for sodium-sulfur batteries that effectively prevents accidents due to active material leakage by dripping into the storage case, but the earlier application uses iron or aluminum metal for the support tube. There is a problem that the corrosion resistance against sodium is not sufficient, and short circuits and ground faults may occur if holes are made in the support tube.Also, as the size of the divided battery with support insulators increases, the volumetric efficiency becomes less efficient. There was a problem that it was inferior.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems and has excellent corrosion resistance against active materials such as sodium and sulfur or their compounds. It is possible to effectively and reliably prevent the occurrence of short-circuit accidents, etc., without affecting other cells, etc., even when active material leaks from a single cell. Furthermore, it has excellent volumetric efficiency and is suitable for battery equipment. It was completed with the aim of providing a protective container for sodium-sulfur batteries that can be made smaller.

(Means for Solving the Problems) The present invention, which has been made to solve the above problems, has a container main body containing Fe as a main component and at least N.
i. A protective container for a sodium-sulfur battery is characterized in that it is a cylinder with a bottom made of a metal containing Cr, and the container body for storing a cell is made of Fe as a main component and contains at least Cr. A protective container for a sodium-sulfur battery is characterized in that it is a cylinder with a bottom made of metal, and at least one surface thereof is covered with a metal whose main component is Ni.
The invention is characterized in that the container body for storing the cell is a cylinder with a bottom made of a metal containing Fe as a main component and at least Ni, and at least one surface thereof is covered with a metal containing Cr as a main component. A third invention of a protective container for a sodium-sulfur battery, in which the container body for storing the cell is a bottomed cylindrical body made of a metal containing Fe as a main component and at least Cr, and the inside thereof is made of an inorganic material containing silica. A fourth invention provides a protective container for a sodium-sulfur battery, characterized in that it is equipped with a protective member, and the container body for accommodating a cell is a bottomed cylinder made of a metal containing Fe as a main component and at least Cr. A fifth invention provides a protective container for a sodium-sulfur battery, characterized in that at least one surface of the container is covered with a metal containing Ni as a main component, and the inside is equipped with a protective member made of an inorganic material containing silica. The main component of the container for storing the cell is a cylinder with a bottom made of a metal mainly composed of Fe and at least Ni. A sixth invention provides a protective container for a sodium-sulfur battery, characterized in that it is equipped with a protective member made of an inorganic material.

(Example) Next, the present invention will be explained in detail with reference to the illustrated embodiments.

In the figure, (1) is a single cell of a sodium-sulfur battery using sodium as the negative electrode active material and sulfur as the positive electrode active material, and the single cell (1) is stored and protected inside the container body (2). In this state, a plurality of batteries are combined into an aggregate and housed in a storage case (not shown) to be used as a sealed high-temperature secondary battery, and the above configuration is common to each invention.

First, FIG. 1 shows an embodiment of the first invention, in which the container body (2) is composed of a bottomed cylindrical body made of a metal mainly composed of Fe and containing at least Ni and Cr. The main component is Fe, 3% by weight or more of Ni, and 1% of Cr.
It is preferable to contain it in an amount of 0% by weight or more. The reason is,
Ni is used to improve corrosion resistance against sodium, which is a negative electrode active material, and if this Ni is less than 3% by weight, sufficient corrosion resistance cannot be exhibited.
Cr improves the corrosion resistance against sodium polysulfide, which is a positive electrode active material.
This is because if the content is less than 0% by weight, sufficient corrosion resistance cannot be exhibited.

Next, FIG. 2 shows an embodiment of the second invention, in which the container body (2) is composed of a bottomed cylinder made of a metal containing Fe as a main component and at least Cr, and has inner and outer surfaces. A metal plating layer (4) containing Ni as a main component is formed on the surface. This plating layer (4) exhibits excellent corrosion resistance against sodium and prevents corrosion of the container body (2), and it is also possible to form the plating layer only on either the inner or outer surface. FIG. 3 shows another embodiment of the second invention, in which the container body (
2) is a bottomed cylindrical body made of a metal containing Fe as a main component and at least Cr, but a bottomed cylindrical body (4a) made of a metal mainly composed of Ni may be combined either inside or outside of the cylindrical body. I can bring it. Furthermore, the unit cell (1) may be covered with a metal foil containing Ni as a main component and then housed in the container body (2).

Next, FIG. 4 shows an embodiment of the third invention, in which the container body (2) is composed of a bottomed cylindrical body made of metal containing Fe as a main component and at least Ni. A metal plating layer (4) whose main component is Cr is formed. This plating layer (4) exhibits excellent corrosion resistance against sulfur and sodium polysulfide and prevents corrosion of the container body (2). It is also possible to form the plating layer only on either the inside or outside surface. It is also possible to combine the inner and outer parts as a cylinder with a bottom, or furthermore, a structure in which the cell (1) is covered with a metal foil mainly composed of Cr and then housed in the container body (2). It is also possible to do this.

Next, FIG. 5 shows an embodiment of the fourth invention, in which the container body (2) is composed of a bottomed cylindrical body made of a metal mainly composed of Fe and containing a small amount of Cr. The inner surface is equipped with a protective member (5) made of an inorganic material containing silica and having a thickness of 1 to 10 mm, for example.
The container body (2) has the function of absorbing sodium or sodium compounds, which are the negative electrode active material of the battery, and converting them into low-activity NaSiOx, and the container body (2) has excellent corrosion resistance against sulfur or sulfur compounds, which are the positive electrode active material. This exhibits the effect of significantly improving the corrosivity of the active material of the container body (2). The protective member (5) may have any structure, such as a fibrous structure that has a large surface area, is lightweight, and does not generate cracks, or a dense structure that prevents the permeation of sulfur and the like.

Next, FIG. 6 shows an embodiment of the fifth invention, in which the container main body (2) is similar to the second invention, but the inner surface has a protective member made of an inorganic material containing silica. 5), which can further improve the corrosion resistance to the active material.

Moreover, FIG. 7 shows an embodiment of the sixth invention, in which the container body (2) is the same as the third invention, or the inner surface of the container body (2) is made of an inorganic material containing silica. ), which can further improve the corrosion resistance to the active material.

In addition, if the outer surface of the container body (2) is further coated with a mica layer (6) as shown in FIGS. It is also possible to achieve effective electrical insulation without using an insulating bottom plate.

Experimental Example 1 5g of sodium was filled in various bottomed metal containers with an outer diameter of 60B, a height of 100-1, and a thickness of 0.2mm.
The container was held at 51,000 degrees Celsius for 51,000 hours, and after cooling to room temperature, the contents of the container were removed and the corroded surface of the container was observed. Table 1 shows the results. Those with corrosion holes penetrating from the corroded surface (inside) to other surfaces (outside) are marked with an X, those with no through holes are marked with an ○, and whether there are any through holes or the corrosion thickness is 01.
Those with good surface conditions of nIn or less are marked with ◎. Also, instead of sodium, sodium polysulfide (Na2S
Table 1 also shows the results obtained under the same conditions and with the same evaluation method except that 3) was used.

Table 1 Experimental Example 2 After lining the inner surface of various metal containers with an outer diameter of 60 mm, a height of 100 mm, and a thickness of 0.2 mm with inorganic fiber felt or coating with ceramics, 5 g of sodium was placed in the second container. Fill and store in air at 350°C for 1500 hours.
Table 2 shows the results of holding the container for 000 hours and 2000 hours, removing the container contents after cooling, and observing the corroded surface of the container.
It was shown to. Note that the evaluations of ×, ○, and ◎ in the table were based on the same criteria as in Table 1.

Table 2 明愼■) Inner wisdom so-called I% (Function) In the first invention, in the first invention, sodium is the negative electrode active material of the unit cell (1), sulfur is the positive electrode active material, or Even if any of these compounds leaks, it will exhibit excellent corrosion resistance against Ni or sodium in the metal, as well as against Cr or sulfur, resulting in the container body (2) This means that leakage of the active material to the outside can be reliably prevented without forming holes due to corrosion. Moreover, in the second invention, the container body (2)
The Ni-based metal covered on the surface exhibits corrosion resistance against sodium, and the bottomed cylinder made of a metal containing Cr exhibits corrosion resistance against sulfur. In the third invention, the metal mainly composed of Cr covered on the surface of the container body (2) exhibits corrosion resistance against sulfur, and the bottomed cylinder made of a metal containing Ni exhibits corrosion resistance against sodium. This will demonstrate the following. Further, in the fourth, fifth, and sixth inventions, sodium or a sodium compound that is a negative electrode active material leaked from the unit cell (1) is absorbed into the protective member (5) containing silica, and reacts with the silica there. In addition to being NaSiOx with low activity, the protective member (5) also exhibits excellent corrosion resistance against sulfur or sulfur compounds that are positive electrode active materials, and the corrosion resistance against any of the active materials is further improved. becomes.

Note that the protective member (5) has a silica content of 80% by weight.
The following impurities include CaO, MgO, K2O, N
It is preferable to use silica-containing inorganic fibers containing 15% by weight or more of alkali and alkaline earth metal oxides in total, such as a2O, because they tend to react with sodium and produce sodium compounds with low activity. The fibers can be formed into felt, paper, bulk, block, etc. shapes. Further, in the protective containers according to the first to sixth inventions described above, the container body (
If the outer surface of 2) is coated with a mica layer (6), the mica layer (6) ensures electrical insulation between each protective container and between the protective container and the storage case. becomes.

It should be noted that sodium-
As a result of storing a sulfur battery cell and operating it at 350''C for 1000 hours, there were no short circuits or ground faults due to active material leakage, confirming the excellent effects of the present invention.

(Effect of the invention) As is clear from the above explanation, in the present invention,
It exhibits excellent corrosion resistance against sodium, sulfur, or their compounds, which are the active materials of sodium-sulfur batteries, and can reliably prevent short circuit accidents caused by leakage. Even if the main body is made thinner, sufficient mechanical strength can be maintained, and the cost can be reduced and the battery can be made smaller.

Therefore, the present invention has solved the problems of the conventional sodium-
As a protective container for sulfur batteries, it can greatly contribute to the development of industry.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the first invention, FIG. 2 is a sectional view showing one embodiment of the second invention, and FIG. 3 is a sectional view showing another embodiment of the second invention. , FIG. 4 is a sectional view showing an embodiment of the third invention, FIG. 5 is a sectional view showing an embodiment of the fourth invention, FIG. 6 is a sectional view showing an embodiment of the fifth invention, 7
The figure is a sectional view showing an embodiment of the sixth invention, and Figs. 8, 9, 1O, and 11 are enlarged views of main parts showing other embodiments in which the outer surface is coated with a mica layer. This is a cross-sectional view (1)
: Single battery, (2): Container body, (4): Plating layer, (4
a): Cylindrical body, (5)・protective member, (6)・mica layer. Patent applicant: Nippon Insulator Co., Ltd. Representative name: Akira Shima Buma
Watanuki Tatsu Difficult Questions
Fumi Yamamoto Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Scope of Claims] 1. A protective container for a sodium-sulfur battery, characterized in that the container body for accommodating a cell is a bottomed cylindrical body made of a metal containing Fe as a main component and at least Ni and Cr. 2. A sodium battery containing a container body in which a cell is housed is a cylinder with a bottom made of a metal containing Fe as a main component and at least Cr, and at least one surface thereof is covered with a metal containing Ni as a main component. Protective container for sulfur batteries. 3. A sodium battery containing a container body for storing a cell, which is a cylinder with a bottom made of a metal containing Fe as a main component and at least Ni, and at least one surface thereof is covered with a metal containing Cr as a main component. Protective container for sulfur batteries. 4. The container body for storing the cell is a cylinder with a bottom made of a metal containing Fe as a main component and at least Cr, and a protective member made of an inorganic material containing silica is attached inside the container body. Protective container for sodium-sulfur batteries. 5. The container body for storing the cell is a cylinder with a bottom made of a metal mainly composed of Fe and at least Cr, and at least one surface thereof is covered with a metal mainly composed of Ni, and the inside is made of a metal containing silica. A protective container for a sodium-sulfur battery, characterized in that it is equipped with a protective member made of equipment. 6. The container body for storing the cell is a cylinder with a bottom made of a metal mainly composed of Fe and at least Ni, and at least one surface thereof is covered with a metal mainly composed of Cr, and the inside is made of a metal containing silica. A protective container for a sodium-sulfur battery, characterized in that it is equipped with a protective member made of equipment. 7. Claim 1, wherein the outer surface of the container body is coated with a mica layer.
7. A protective container for a sodium-sulfur battery according to 2, 3, 4, 5 or 6.