JPH0364868A - Sodium-sulfur cell and manufacture thereof - Google Patents

Abstract

PURPOSE:To fill up a negative electrode chamber with sodium with good airtightness for improving safety by welding a cylindrical body having a hole and an upward-facing projection on the base while having a plurality of inward- facing projections on the top to the lower part for being used for a negative electrode collector container. CONSTITUTION:While welding a cylindrical body 13 having a hole 14' and an upward-facing projection 14 on the base and having inward-facing projections 13' on the top for being made a negative electrode collector container 15, the negative electrode collector container 15 is welded to a negative electrode lid 3. Then, while arranging a sodium tank 17 inside the container 15 and fixing the side of the sodium tank 17 with the inward-facing projections 13', the projection 14 on the base digs a hole for vacuum filling up the negative electrode chamber inside with sodium 8. Time and parts required for filling up can be reduced thereby and the sodium tank 17 and the negative electrode collector container 15 can also be fixed so that airtightness inside the negative electrode chamber at the time of sodium filling up can be easily maintained. Further, a spot where sodium 8 is exhausted inside metal fibers 12 is not generated so that a cell life can be lengthened.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a sodium-sulfur battery and a method for manufacturing the same. More specifically, it provides a battery whose cathode chamber can be airtightly filled with sodium and whose safety can be improved. It concerns the manufacturing method.

Conventional technology and its problems Sodium-sulfur batteries have a completely sealed structure 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 β''-alumina. This is a high-temperature secondary battery.

The conventional structure of such a sodium-sulfur battery will be explained with reference to FIG. An α-alumina ring 2 is glass-soldered to the upper end of the solid electrolyte tube 1, and a cathode lid 3 and an anode lid 4 are joined to the upper surface and the lower surface of the α-alumina ring 2 and 2 by thermopressure, respectively. 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 cathode terminal 5 is sealed. Such a cathode chamber structure consists of a cylindrical sulfur molded body 1o
is inserted into a battery case 9 which also serves as an anode current collector, to which an anode current collector terminal 11 is welded, and the anode current collector terminal 11 is bent outward, and the upper end of the battery case 9 is connected to the anode cover 4. Vacuum welded and completely sealed.

In the sodium-sulfur battery with the above structure, sodium 8 is vacuum-filled from the upper end of the cathode terminal 5, so sodium may adhere to the inside of the cathode terminal 5 after filling, and the upper end of the cathode terminal 5 may be sealed. There was a problem in that the stop was incomplete and defects occurred. Immediately after filling the sodium 8, the battery surrounding gas is sucked into the metal fiber 7 through the cathode vibro, the sodium 8 impregnated in the metal fiber 7 is forcibly discharged, and the place where sodium 8 is depleted is removed from the metal fiber 7. Particularly on the surface of the solid electrolyte tube 1,
There is a problem in that the current density on the surface of the solid electrolyte tube 1 becomes non-uniform, causing deterioration of the solid electrolyte tube 1.

Furthermore, when the solid electrolyte tube 1 is damaged, sulfur and sodium react directly, causing active materials to leak out and damaging adjacent normal batteries, resulting in a large-scale accident.

OBJECTS OF THE INVENTION The present invention overcomes the above-mentioned drawbacks by facilitating filling with sodium, facilitating welding after filling, eliminating sodium-depleted points in metal fibers, and preventing damage to batteries. The purpose of this technology is to reduce the amount of damage caused by the damage, and also to improve safety by creating a structure that prevents the active material from leaking even if it is damaged.

Structure of the Invention The sodium-sulfur battery and the manufacturing method thereof of the present invention are such that a cylindrical body having a hole and an upwardly directed protrusion on the bottom surface and a plurality of inwardly directed protrusions on the top surface is welded to the lower part to collect the cathode. This cathode current collector container is welded to the inner circumferential edge of the cathode lid, a sodium tank is placed inside the container, the sides of the sodium tank are fixed with inwardly directed protrusions, and holes are made with the protrusions on the bottom. The cathode chamber is vacuum filled with sodium.

EXAMPLES The present invention will be explained below using examples. FIG. 1(a) 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 designated by the same reference numerals.

The glass solder bonding between the solid electrolyte tube l and the α-alumina ring 2 is carried out in the same way as before, and the cathode cover 3 made of aluminum-coated iron is thermo-pressure bonded to the upper surface of the α-alumina ring 2, and the same is applied to the lower surface. The anode cover 4 made of the same material is bonded under heat and pressure. An anode auxiliary cover 4' is welded to this anode cover 4. A metal fiber 12 made of stainless steel felt is wound and housed in the solid electrolyte tube 1 so as to form a center hole, thereby forming a cathode chamber. On the other hand, the top surface has a plurality of protrusions 13° facing inward, and the bottom surface has holes 14° and protrusions 14 facing upward.
A cylindrical body 13 as shown in FIG. Weld.

The hole 14° and the upwardly directed protrusion 14 can be formed by making a ■-shaped cut in the bottom surface of the cylindrical body 13 and directing this cut portion upward. Next, the second
As shown in the cross-sectional view of the main part in Figure (al), an O-ring 16 is arranged on the inner bottom surface of the cylinder 13, and nitrogen gas, helium gas, argon gas, or a mixed gas is sealed inside, and sodium 8 is placed in the cathode current collector container 15, and after evacuating the cathode chamber from the hole 14' under heating, the sodium tank 17 is lowered so as to face the inside of the cylindrical body 13. The side surface of the sodium tank 17 is fixed with a plurality of protrusions 13 degrees, and the O-ring 16 hermetically isolates the inside and outside of the cathode chamber, and the protrusion 14 on the bottom of the cylinder body 13 makes a hole in the bottom of the sodium tank 17 to seal the inside of the cathode chamber. Vacuum filling sodium 8. This vacuum filling is done in sodium tank 1.
This is done by the difference between the internal pressure of No. 7 and the internal pressure of the cathode chamber.

2) shows the state in the middle of filling the sodium 8. After filling, the sodium tank 17 is cooled and pulled out while rotating, and the O-ring 16 is removed. next,
A cathode terminal 18 is vacuum welded to the upper inner peripheral edge of the cathode current collector container 15 to seal the cathode chamber to form a cathode chamber structure. This cathode chamber structure is inserted into a battery case 9 containing a cylindrical sulfur molded body 10, and the upper end of the battery case 9 and the anode auxiliary lid 4' are vacuum welded to complete the battery.

Now, we manufactured 10 cells each of the battery of the present invention as shown in Fig. 1 and the conventional battery as shown in Fig. 3, and
A heat cycle test was conducted at a temperature increase/decrease rate of approximately 50°C to 200°C/h, and the results are shown in Table 1. In Table-1,
The numerator indicates the number of batteries with active material leakage or internal short circuits, 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.

Margin Table-1 Below Table-1 shows that when a conventional battery is damaged, the active material leaks out and all of it is short-circuited, whereas the battery of the present invention is less likely to be damaged, and even if it is damaged, the active material etc. No leakage,
No internal short circuit was observed. In addition, since the manufacturing method eliminates the need for a cathode pipe, the time and parts required for filling can be reduced.
7 and the cathode current collector container 15 are fixed, it is easy to maintain airtightness inside the cathode chamber when filling with sodium, and there is no place where sodium 8 is depleted in the metal fiber 12 after filling with sodium 8.

Effects of the Invention As described in detail in the Examples, the battery of the present invention has good airtightness, so its quality is stable. Further, even if the battery is damaged, the lower part of the cathode current collector container is fused due to the heat of the direct reaction between sodium and sulfur, thereby preventing the occurrence of internal short circuits. Furthermore, since there is no place in the metal fiber where sodium is depleted after filling with sodium, the battery life can be extended. On the other hand, this manufacturing method can reduce the time and parts required for filling sodium, so it can be adapted to mass production.

[Brief explanation of drawings]

Figure 1 (al is a sectional view of the main parts of the sodium-sulfur battery of the present invention, Figure 1 (b) is a perspective view of the cylinder, Figure 2 (a),
(b) is a diagram for explaining the method for manufacturing a sodium-sulfur battery of the present invention, and FIG. 3 is a cross-sectional view of a conventional sodium-sulfur battery. ■...Solid electrolyte tube 2...α-alumina ring 3
...Cathode M 4...Anode cover 4"...Anode auxiliary cover 7,12...Metal fiber 8...
・Sodium 13...Cylinder 13°...Protrusion 14...Protrusion 14゛...Hole 15...Cathode current collector container 16...O ring 17...Sodium tank 5.18... cathode terminal

Claims (1)

[Claims] 1) α at the upper end of the sodium ion conductive solid electrolyte tube
- an alumina ring is joined, and a cathode lid is heat-pressure welded to the upper surface of the α-alumina ring, and has a cathode terminal welded to the cathode lid to form a cathode chamber in the solid electrolyte tube; and An anode lid is heat-pressure bonded to the lower surface of the α-alumina ring, and a battery case is welded to the anode lid to cover the solid electrolyte tube from below and form an anode chamber in the gap between the solid electrolyte tube and the anode lid. In the sodium-sulfur battery, a cylindrical body having a hole and an upwardly directed protrusion on the bottom surface and a plurality of inwardly directed protrusions on the top surface is welded to the lower part to serve as a cathode current collector container, and the bottom surface is disposed so as to be in contact with the upper surface of the metal fiber in the solid electrolyte tube, and welding the upper part of the cathode current collector container to the inner peripheral edge of the cathode lid,
A sodium-sulfur battery characterized in that a cathode terminal is welded to the upper inner peripheral edge of the cathode current collector container to seal the cathode chamber. 2) The sodium-sulfur battery according to claim 1, wherein the plurality of inwardly directed protrusions are triangular in shape and have different lengths. 3) The sodium according to claim 1 or 2, characterized in that a V-shaped notch is made in the bottom surface of the cathode current collector container, and a hole and a protrusion are formed with the notch facing upward.
sulfur battery. 4) An α-alumina ring is glass soldered to the upper end of the solid electrolyte tube that conducts sodium ions, and a cathode cover is heat-pressure bonded to the upper surface of the α-alumina ring, and an anode cover is bonded to the lower surface of the α-alumina ring. A cathode current collector container is prepared in which metal fibers are stored to form a cathode chamber, and a cylindrical body having a hole and upwardly directed protrusions on the bottom surface and a plurality of inwardly directed protrusions on the top surface is welded to the lower part. After welding the bottom of the cathode current collector container to the bottom of the cathode lid so that it contacts the metal fibers, an O-ring is placed on the inner bottom of the cylinder, and nitrogen gas, helium gas, or argon gas is injected into the inside. A sodium tank filled with sodium or a mixed gas is placed in the cathode current collector container, and after evacuating the cathode chamber from the hole in the bottom of the cylinder under heating, the sodium tank is lowered. After fixing the side surface of the sodium tank with a plurality of inwardly facing protrusions of the cylindrical body, and vacuum-filling the cathode chamber with sodium by punching a hole in the sodium tank using the protrusions on the bottom of the cylindrical body, the cathode current collector container is A cathode terminal is welded to the upper inner peripheral edge to form a cathode chamber structure.Meanwhile, a battery case into which a cylindrical sulfur molded body is inserted is prepared, and the cathode chamber structure is inserted into the hollow part in the center of this sulfur molded body. A method for manufacturing a sodium-sulfur battery, characterized in that after insertion, the anode auxiliary lid welded to the anode lid and the upper end of the battery case are welded to vacuum-seal the inside of the anode chamber.