JP2504840B2 - Bonding glass ring for forming sodium-sulfur battery and bonding method using the bonding glass ring - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a bonded glass ring for forming a sodium-sulfur battery and a bonding method using the bonded glass ring, and more specifically to a bottomed sodium-sulfur battery. Bonding glass capable of improving bonding work efficiency between a cylindrical solid electrolyte and an insulator ring, and manufacturing a bonding glass ring for forming a sodium-sulfur battery having almost no residual bubbles in the bonding glass at low cost and with high accuracy. A ring,
The present invention relates to a joining method using the glass ring.

[Prior Art] A sodium-sulfur battery has molten metal sodium that is a cathode active material on one side and molten sulfur that is an anode active material on the other side, and both have a selective permeability to sodium ions. Isolate with beta-alumina solid electrolyte, 300
It is a high temperature secondary battery operated at ~ 350 ° C.

The structure of such a sodium-sulfur battery is, for example, as shown in FIG. 6, a cylindrical anode container 2 for accommodating a conductive material 1 for anode such as carbon felt impregnated with molten sulfur S as an anode active material. , Is connected to the upper end of the anode container 2 via an insulator ring 3 made of, for example, alpha alumina,
Also, a cathode container 4 for storing molten metal sodium Na, and a bottomed cylindrical beta-alumina tube 5 joined to the inner peripheral portion of the insulator ring 3 and having a function of selectively transmitting sodium ions Na ^+. It consists of A cathode tube 7 extending downward through the cathode container 4 to near the bottom of the beta-alumina tube is penetratingly supported in the central portion of the upper lid 6 of the cathode container 4.

In the sodium-sulfur battery having the above configuration,
During discharge, molten metal sodium emits electrons to become sodium ions, which pass through the beta alumina solid electrolyte and move to the anode side, reacting with the anode sulfur and the electrons that have passed through the external circuit to form sodium polysulfide. Generates 2V
Generates a voltage of the order of magnitude. On the contrary to discharging, during charging, a reaction of producing sodium and sulfur occurs.

Conventionally, when joining a bottomed cylindrical solid electrolyte made of beta alumina or the like and an insulator ring made of alpha alumina or the like, a paste prepared by mixing glass powder with a binder and water or an organic solvent is used outside the open end of the solid electrolyte. In addition to the method of applying both on the surface or on the inner surface of the insulator ring and fitting them together by heating, a bonded glass ring in which bonded glass is formed in a ring shape is prepared, and the bonded glass ring is used as a solid electrolyte. It has been practiced to join the two by heat-treating them after inserting them between the insulating rings.

Among these, in the latter method, various methods for producing a bonded glass ring can be considered. As a conventionally known method for producing a bonded glass ring, there is a method in which a binder is added to raw material glass powder, mixed and granulated, shaped into a ring, and then sintered to produce a sintered ring. .

[Problems to be Solved by the Invention] However, in the above sintered body ring, a large amount of bubbles remain in the obtained sintered body glass, and when it is used, the bonding strength is lowered. there were.

In addition to the sintered body ring, a method of producing a filamentous material from molten glass and rolling and cutting it to obtain a glass ring. Further, producing a plate from molten glass and cutting and rolling it. A method of obtaining a glass ring is also considered. However, both methods have drawbacks in that there is a problem in dimensional accuracy and the cost is high, and there is also a problem in that the amount of one glass ring is insufficient with respect to the amount of glass required for joining.

[Means for Solving the Problems] Therefore, the present inventors have completed the present invention as a result of various studies in order to solve the above conventional problems.

That is, according to the present invention, a sodium-sulfur battery forming bonding glass ring used for firmly bonding the insulator ring to the outer peripheral portion of the open end of the bottomed cylindrical solid electrolyte,
The bonded glass ring is prepared by melting a glass raw material to form a glass frit, re-melting the glass frit to form a tube, and cutting the tube-shaped formed body to separate the cylindrical solid electrolyte and the insulating ring. Sodium characterized by being formed in a ring shape that can be fitted to the joint
A bonded glass ring for forming a sulfur battery is provided.

Further, according to the present invention, when the insulator ring is fixedly joined to the outer peripheral portion of the open end of the bottomed cylindrical solid electrolyte, the bottom end of the cylindrical solid electrolyte is erected on the jig with the open end portion facing downward. In addition, an insulator ring is arranged on the outer peripheral portion of the open end of the bottomed cylindrical solid electrolyte, and the bonded glass ring formed in the ring shape is then attached to the outer peripheral portion of the open end of the bottomed cylindrical solid electrolyte and the insulator. A method for joining a bottomed cylindrical solid electrolyte and an insulator ring, characterized by joining an insulator ring to the outer peripheral portion of the open end of the bottomed cylindrical solid electrolyte by charging it between the ring and the ring. Will be provided.

[Operation] According to the present invention, a bonded glass ring is used for firmly bonding an insulator ring to the outer peripheral portion of the open end of a bottomed cylindrical solid electrolyte. The bonded glass ring melts raw material glass to form a glass frit. It is obtained by making and remelting this glass frit.

In this way, the glass frit is remelted to form the bonded glass ring, so that the viscosity of the glass is reduced and bubbles are removed, and as a result, a glass ring having almost no bubbles and good dimensional accuracy can be provided.

This bonded glass ring is preferably formed so that its volume is equal to or larger than the glass amount required for bonding the solid electrolyte and the insulator ring, and thus bonded with a fixed amount of glass. Is possible,
Further, it is not necessary to use a number of glass rings, which improves working efficiency.

Further, in the present invention, it is preferable to use a raw material glass frit having a thermal expansion coefficient equal to or smaller than that of the solid electrolyte. When used in a sodium-sulfur battery, the joined body of the bottomed cylindrical solid electrolyte and the insulator ring means that the metal container and the insulator ring are joined together, and the battery is operated at a battery operating temperature of about 350 ° C. Bending stress acts on the joint between the insulator ring and the bottomed cylindrical solid electrolyte due to expansion of internal sulfur, sodium metal, sodium polysulfide, carbon mat, and the like. Therefore, it is important that the glass after joining the bottomed cylindrical solid electrolyte and the insulator ring does not have defects such as cracks.

Therefore, in the present invention, the bottomed cylindrical solid electrolyte and the insulator ring are joined as follows. That is, first, the bottomed cylindrical solid electrolyte is erected on the jig with the open end side facing downward. Next, after arranging the insulator ring on the outer peripheral portion of the open end of the bottomed cylindrical solid electrolyte, the bonded glass ring of the present invention is charged between the outer peripheral portion of the open end of the bottomed cylindrical solid electrolyte and the insulator ring. Then, heat treatment is performed at a temperature of about 1050 ° C. to bond the insulator ring to the outer peripheral portion of the open end of the bottomed cylindrical solid electrolyte. As a result, the tensile stress of the residual stress in the joint is reduced, the cantilever bending strength is increased, and the occurrence of cracks is suppressed.

[Examples] Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.

Example 1 Using silica sand, alumina, sodium carbonate, and boric acid raw materials having a purity of 99% or more and a particle size of 1 μm or less in average particle size,
Glass composition is SiO ₂ 63 wt%, Al ₂ O ₃ 7.5 wt%, Na ₂ O9.5
A borosilicate glass frit composed of 20% by weight of B ₂ O ₃ was prepared by the following procedure. First, each raw material was weighed so as to have a total weight of 5 kg so as to have the above glass composition, and dry-mixed in a porcelain pot mill for 30 minutes. Each 500 g of this mixture was put into a chamotte crucible and melted by heat treatment in an Elema electric furnace at a temperature of 1450 ° C for 1 hour to form a solution. Then, the crucible was taken out from the Elema electric furnace and filled with water. It was put into a stainless steel vat and rapidly cooled to form a frit.

Then, the created frit is roughly crushed with a roll crusher and put into a platinum crucible with an internal volume of 200 ml about 2/3,
It was re-melted by heating at a temperature of 1500 ° C. for 2 hours in an electric electric furnace. Remelting by this high-temperature heat treatment reduced the viscosity of the glass, and the bubbles in the molten glass spontaneously defoamed. After remelting, using the inner mold, outer diameter 27 mm, wall thickness
A 1 mm pipe was pulled out, cooled, and cut with a diamond cutter to form a glass ring having a height of 2 mm, a rectangular cross section in the longitudinal direction, and almost no bubbles inside.

(Example 2) Using the glass ring produced in Example 1 to join the bottomed cylindrical solid electrolyte and the insulator ring made of alpha alumina, first, as shown in FIG. 1, the alumina setter 11 for joining was used. , And set the insulator ring 12 on top of it with the taper part facing upward, and further, the bottomed cylindrical solid electrolyte 13
Was set so that the open end side thereof faced downward. Next, as shown in FIGS. 2 (a) and 2 (b), the bonded glass ring 14 is charged from above the bottomed cylindrical solid electrolyte 13 and set on the taper portion of the insulator ring 12, and the electric furnace is used. It heat-processed at 1050 degreeC according to the heat curve for joining shown in FIG. The cross section of the joint after heat treatment is shown in Fig. 3, and the joint glass 14 '
Was buried in the joint surface between the bottomed cylindrical solid electrolyte 13 and the insulator ring 12 and the taper portion of the insulator ring 12.

After the bottomed cylindrical solid electrolyte and the insulator ring were joined by the above-mentioned operation, the joint cross section was observed with an optical microscope. As a result, as shown in FIG. 5, almost all bubbles remained in the glass after joining. In fact, the bonded glass ring of the present invention was proved to have good performance.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a glass ring having good dimensional accuracy and almost no bubbles, and therefore, it is possible to uniformly melt and pour glass into a joint portion, and there is no bubbles. Bonding with high strength can be realized.

[Brief description of drawings]

1 to 3 are explanatory views sequentially showing the operation procedure of the joining method using the glass ring of the present invention, and FIG.
It is a partially expanded view of FIG. FIG. 4 is a graph showing a heat curve for joining, FIG. 5 is an explanatory view showing a state of a joined glass using the glass ring of the present invention, and FIG. 6 is a schematic sectional view showing a constitution of a sodium-sulfur battery. . 11 …… Alumina setter, 12 …… Insulator ring, 13 ……
Bottomed cylindrical solid electrolyte, 14 …… Bonded glass ring.

Claims (2)

(57) [Claims] 1. A bonded glass ring for forming a sodium-sulfur battery, which is used for firmly bonding an insulator ring to an outer peripheral portion of an open end of a bottomed cylindrical solid electrolyte, wherein the bonded glass ring melts a glass raw material. To form a glass frit, re-melt the glass frit to form a tube, and cut the tubular formed body to form a ring shape that can be fitted to the joint between the cylindrical solid electrolyte and the insulating ring. A bonded glass ring for forming a sodium-sulfur battery, characterized in that 2. When the insulator ring is fixedly joined to the outer peripheral portion of the open end of the bottomed cylindrical solid electrolyte, the open end of the bottomed cylindrical solid electrolyte faces downward and is erected on a jig. An insulator ring is disposed on the outer peripheral portion of the open end of the bottomed cylindrical solid electrolyte, and the bonded glass ring according to claim 1 is provided between the outer peripheral portion of the open end of the cylindrical solid electrolyte with the bottom end and the insulator ring. A method for joining a bottomed cylindrical solid electrolyte and an insulator ring, characterized in that the insulator ring is joined to the outer peripheral portion of the open end of the bottomed cylindrical solid electrolyte after being charged into the.