JPH02197060A - Sodium-sulfur battery - Google Patents

Abstract

PURPOSE:To prevent breakage of a solid electrolyte tube by providing a throughhole in a cathode terminal, threading a cathode collecting body from under this throughhole, forming a protruding part in a form surrounding the throughhole at the top, and disposing a sealing cover in this protruding part for closing a cathode chamber. CONSTITUTION:A convex part 2' is provided in the top surface of an alpha-alumina ring 2, a cathode cover 3 is jointed inside this convex part 2', and an anode cover 4 is jointed on the outer side by heat and pressure respectively for preventing mutual short-circuiting. The anode cover 4 is welded with an anode auxiliary cover 12 consisting of stainless, chrome-diffused iron, and aluminum- diffused iron and having a concentric wavy part. A cathode terminal 5 is welded with the cathode cover 3 covering a top open end of a solid electrolyte tube 1, and a throughhole 5' is provided at the center of the terminal 5. In the meanwhile, a protruding part 13 is formed at the top surface of the terminal 5 surrounding the hole 5', and molten sodium 8 is filled in metal fibers 7 in vacuum. A sealing cover 14 is thus vacuum-welded with the forward end of the protruding part 13 for vacuum-sealing a cathode chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a sodium-sulfur battery, and more particularly to a structure that prevents damage, improves safety, and facilitates filling with sodium.

Prior art and its problems A sodium-sulfur battery is a complete battery in which sodium as a cathode active material and sulfur as an anode active material are separated by a sodium ion conductive solid electrolyte tube such as It is a high temperature secondary battery with a sealed structure.

The conventional structure of such a sodium-sulfur battery will be explained with reference to FIG. An α-alumina ring 2 is bonded to the upper end of the solid electrolyte tube 1 by glass soldering, and a cathode cover 3 is bonded to the upper surface of the α-alumina ring 2, and an anode cover 4 is bonded to the lower surface thereof by heat pressure. A cathode terminal 5 is welded to the cathode lid 3, and a cathode vibro serving as a cathode current collector is welded through the center of the cathode lid 3, and the lower part thereof is inserted into the solid electrolyte tube 1.

Metal fibers 7 are disposed inside this solid electrolyte tube 1, and approximately 15
After evacuating the inside of the solid electrolyte tube 1 from the cathode vibro while keeping the temperature at 0°C, sodium 8 melted at the same temperature.
is vacuum filled, and after filling, the upper end of the logic terminal 5 is sealed. Such a cathode chamber structure consists of a cylindrical sulfur molded body 10.
is inserted into a battery case 9 which also serves as an anode current collector, and an anode current collector terminal 11 is welded thereto, and the anode current collector terminal 11 is bent outward, and its upper end is vacuum welded to the anode lid 4. completely sealed.

In a sodium-sulfur battery having the structure as described above,

In the process of increasing the temperature to the operating temperature of 550℃, the sulfur molded body 10
expands thermally, and the solid electrolyte tube 1 receives bending stress. However, since the solid electrolyte tube 1 is firmly joined to the α-alumina ring 2 by glass solder, the solid electrolyte tube 1 may be damaged at the glass solder joint due to the bending stress. When the solid electrolyte tube 1 is damaged in this way, sulfur and sodium react directly, the internal pressure increases, the cathode fE3 peels off from the top surface of the α-alumina ring 2, and the active material leaks out, causing damage to adjacent normal cells. There was a problem that the battery could also be damaged, leading to a large-scale accident. In addition, since sodium 8 is vacuum filled from the upper end of the cathode terminal 5, sodium may adhere to the inside of the cathode terminal 5 after filling, resulting in incomplete sealing of the upper end of the cathode terminal 5, resulting in defects. There was a problem that occurred.

Purpose of the Invention The present invention solves the above-mentioned drawbacks, and has a shape in which a through hole is provided in the cathode terminal welded to the cathode lid, a cathode current collector is screwed from below the through hole, and the through hole is surrounded from above. By forming a protrusion with 1 and placing a sealing lid inside this protrusion to seal the cathode chamber, the upper part of the through hole is completely sealed, and the cathode current collector can be melted off in the event of battery damage. Structure of the Invention The sodium-sulfur battery of the present invention has a convex portion on the upper surface of the α-alumina ring, and an anode cover is thermo-pressure bonded to the outside of this convex portion. Then, this anode cover and the battery case were welded together via an anode auxiliary cover having a concentric wavy part, and a cathode cover was heat-pressure bonded to the inside of the convex part, and a through hole was provided in the cathode cover. The cathode terminal is welded, a cathode current collector is screwed from below the through hole, a protrusion is formed above the through hole in a shape that surrounds the through hole, and a sealing lid is placed inside this protrusion to seal the cathode chamber. This is what I did.

EXAMPLES The present invention will be explained below using examples. FIG. 1 is a sectional view of the main parts of the sodium-sulfur battery of the present invention, and parts common to those in FIG. 3 are given the same reference numerals.

In FIG. 1, the solid electrolyte tube 1 has an outer diameter of 569 mm with an open top. βI- with inner diameter 5Qsm and length 170 dew
A ring 2 made of alumina and having an outer diameter of 76 m, an inner diameter of 50 m, and a thickness of 10 mg + a-7 yt is glass soldered to the upper open end of the α-alumina ring 2. A cathode cover 3 is bonded to the inside of the convex portion 2', and an anode cover 4 is bonded to the outside by heat pressure to prevent mutual short circuit. The cathode cover 4 is in WI contact with an anode auxiliary cover 12 made of stainless steel, lime diffused iron, or aluminum diffused iron and having concentric wavy portions. A cathode terminal 5 is welded to the cathode lid 3 so as to cover the upper open end of the solid electrolyte tube 1. A through hole 5' is provided in the center of the cathode terminal 5, and a large screw with a diameter Qms is provided at the bottom. A cathode current collector 6' made of aluminum is screwed into this screw hole.
Insert the other end into the metal fiber 7 to a depth of 5 cm.

On the other hand, on the upper surface of the cathode terminal 5, a protrusion 13 is formed to surround the through hole, as shown in the enlarged view of FIG. Vacuum filling. In this way, as shown in the enlarged view of FIG. 2, the tip of the protrusion 15 is brought into contact with the sealing lid 14 under vacuum, thereby sealing the cathode chamber under vacuum. A cylindrical part 5' is formed in the upper part of the through hole 5' of the cathode terminal 5, a threaded part is provided inside this cylindrical part 5', and the cathode connecting terminal 15 is screwed into this threaded part with a bolt 15'. do. On the other hand, a battery case 9 into which a cylindrical sulfur molded body 10 is inserted is attached from below the solid electrolyte tube 1, and the upper end is welded to the anode auxiliary lid 12 to seal the Vh electrode chamber, and the upper A battery case 111 to which an anode terminal 16 is welded
7 is welded, and the anode connecting terminal 18 is tightened to the anode terminal 16 with a nut to complete the battery.

Now, we manufactured 10 cells each of the battery of the present invention as shown in Figure 1 and the conventional battery as shown in Figure 3, and heated them in a room m = 350°C.
A heat cycle test was conducted at a rising/lowering rate of 50°C to 200°C/h, and the results are shown in Table 1. In Table-1,
The numerator indicates the number of batteries from which active material leaked, and the denominator indicates the number of damaged batteries. Note that when a battery is damaged, the voltage drops rapidly, so we checked for a damaged battery based on the drop in voltage.

Table 1 Table 1 shows that conventional batteries often break during heat cycle tests up to 10 cycles, and even when they break, active materials leak out and two-thirds of them are short-circuited.
In the battery of the present invention, only one cell was damaged in the heat cycle test up to 10 cycles.

Next, the batteries that were not damaged were subjected to a battery destruction test by overcharging at 350°C, and the results are shown in Table 2.

From Table 2, it can be seen that while the conventional battery was damaged and short-circuited, the battery of the present invention had 0 short-circuited cells. By providing an anode auxiliary lid with a wavy part to transfer stress-induced displacement upwards of the solid electrolyte tube, it is possible to absorb bending stress during heat cycle tests and battery operating temperatures. damage can be prevented.

Furthermore, even if the battery is damaged, the cathode current collector 6' is fused due to the heat of direct reaction between IJium and sulfur, thereby preventing short circuits from occurring inside the damaged battery. Furthermore, when filling with IJ, it is possible to prevent IJ from adhering to the inside of the cathode terminal.

[Brief explanation of the drawing]

1...Solid electrolyte tube 2'-・Protrusion 4.- Yang plate lid 5'...Through hole 6'・-Cathode current collector 15...Protrusion

Claims (2)

[Claims] (1) An α-alumina ring is bonded to the upper end of a sodium ion conductive solid electrolyte tube, a cathode lid and an anode lid are thermo-pressure bonded to this α-alumina ring, and welded to the anode lid, the solid electrolyte A sodium-sulfur battery comprising: a battery case that covers a tube from below to form an anode chamber in a gap with the solid electrolyte tube; and a cathode cover that is welded to the cathode cover to form a cathode chamber within the solid electrolyte tube. In the above α-
A convex part is provided on the upper surface of the alumina ring, an anode cover is thermo-pressure bonded to the outside of this convex part, and the anode cover and the battery case are welded together via an anode auxiliary cover having a concentric wavy part. A cathode lid is heat-pressure bonded to the inside of the convex portion, a cathode terminal with a through hole is welded to the cathode lid, a cathode current collector is screwed from below the through hole, and the through hole is surrounded from above. 1. A sodium-sulfur battery characterized in that a protrusion is formed in the shape, and a sealing lid is disposed within the protrusion to seal a cathode chamber. (2) The sodium-sulfur battery according to claim 1, wherein the cathode current collector is an aluminum tube whose lower end is inserted above the metal fiber.