JPH09129197A - Sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an assembly sealing plate in which the contact resistance rise between a positive electrode terminal and a positive electrode lead plate is prevented by inserting the lower axis portion of the T-shaped positive electrode terminal into the central open hole portion of the heat-treated sealing plate, and welding the lead plate connecting coupling plate to the bottom face of the positive electrode terminal. SOLUTION: A circular sealing plate 1 having an open hole in the central portion is made of polypropylene resin, is heat-treated at 100 to 160 deg.C, and has a thickness of 1.0 to 4.0mm. A positive electrode terminal 2 is stainless steel-made, is T-shaped, is composed of a cylindrical head portion 2a of a larger diameter than that of the open hole portion of the sealing plate 1 and a columnar lower axis portion 2f of a smaller diameter than that of the head portion 2a, and the lower axis portion 2f is pressed into the open hole portion of the sealing plate 12 so that the head portion 2a comes on a battery outside side. A coupling plate 3 for a positive electrode lead plate connection is made of a circular titanium of 0.1 to 0.5mm thick, the bottom face of the positive electrode 2 is spot-welded and fixed in the central portion thereof, and the ratio of a coupling plate outer diameter/a sealing plate outer diameter is set to 0.85 or less. By using the assembly sealing plate having such a structure, it is possible to obtain an excellent sealed battery.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an improvement in an organic electrolyte battery using lithium metal as a negative electrode active material.
In particular, the present invention relates to the structure of an assembled sealing plate that prevents an increase in contact resistance between the positive electrode terminal and the positive electrode lead plate.

[0002]

2. Description of the Related Art Generally, in a so-called organic electrolyte battery in which a fluorocarbon or manganese dioxide is used as a positive electrode active material and a light metal such as lithium or aluminum is used as a negative electrode active material and is combined with an organic electrolytic solution, the positive electrode is inside the battery. When metals such as iron, nickel, and copper are used for the metal parts that are in contact with, for example, the positive electrode current collector, lead plate, sealing plate, and other parts, these metals are dissolved by a kind of electrochemical reaction with the positive electrode. However, battery performance often deteriorates significantly.

For this reason, high-purity aluminum or titanium having organic electrolyte resistance is used in the above-mentioned places. There is a synthetic resin-based assembled sealing plate using these metals as shown in FIG. The assembled sealing plate of FIG. 4 has a lower washer 5 made of titanium with a head 4a of a rivet 4 made of aluminum having excellent corrosion resistance inside a battery, in a through hole provided in a central portion of a sealing plate 1 made of a thermoplastic resin. Insert in the mated state. Then, the rivet leg portion 4b protruding to the outside of the battery is fitted with an upper washer 6 which is excellent in workability and can be welded and has a high strength, for example, nickel-plated iron, and the leg portion 4b is caulked and deformed to form the upper washer 6. It is integrated with the sealing plate 1. Further, a cap 7 which also functions as a positive electrode terminal of nickel-plated iron is spot-welded to the upper washer 6 so as to surround the rivet leg portion 4b which has been caulked and deformed to form an assembled sealing plate.

[0004]

When the opening portion of the battery case 8 is sealed using the assembly sealing plate having such a structure as shown in FIG. 5, the lower washer made of titanium is connected to the positive electrode lead plate 9. The surface 5 of the aluminum rivet 4 is brought into surface contact with the head 4a of the aluminum rivet 4 by caulking and deforming pressure to ensure electrical conduction. However, when a thin oxide film has already been formed on the aluminum rivet head 4a at the time of use, or when the battery is used in a cold atmosphere, the sealing plate 1 made of a thermoplastic resin shrinks in the diameter and thickness directions. Then, the contact between the rivet head 4a and the lower washer 5 is loosened, and the internal resistance of the battery is increased, so that the battery output cannot be taken out sufficiently. In order to solve this drawback
According to Japanese Patent No. 177, the base of the shaft of the aluminum rivet 4 is made larger than the other, and the large diameter is pressed into the titanium lower washer 5 to remove the oxide film on the surface of the aluminum rivet. A method has been devised to ensure the electrical continuity between the two without being affected by the contraction of the sealing plate during cold weather. However, this method is effective in ensuring the electrical connection between the rivet 4 and the lower washer 5, but cannot be expected to be effective in the electrical connection between the rivet 4 and the upper washer 6. That is, the electrical connection between the rivet 4 and the upper washer 6 is also secured by the caulking deformation pressure of the leg portion 4b of the aluminum rivet 4, so that the aluminum can be used while the battery is used for a long time in a severe natural environment. When a thin oxide film is formed on the surface of the rivet leg 4b made of aluminum, or when the battery is used in a cold atmosphere, the rivet 4 made of aluminum and the lower washer 5 are used.
Similar to the above case, a phenomenon such as loose contact between the rivet leg portion 4b and the upper washer 6 occurs, which causes a problem that the internal resistance of the battery becomes high and the battery output cannot be sufficiently taken out.

The present invention solves the above-mentioned conventional problems, does not increase the resistance of the terminal portion even if it is used for a long period of time in a cold atmosphere or a harsh natural environment, and further has liquid leakage resistance and explosion-proof action. By using the assembled sealing plate provided together, a battery having stable internal resistance, excellent leakage resistance and safety, and long-term reliability is supplied.

[0006]

In order to solve this problem, according to the present invention, a positive electrode terminal made of a T-shaped metal rivet with electrolyte resistance is provided with a head portion at the central opening of a heat-treated sealing plate. The lower shaft is press-fitted to the outside of the battery, and the electrolyte resistant connection plate for connecting the lead plate is welded to the lower end of the lower shaft of the T-shaped rivet to simultaneously establish electrical conduction and fix the positive terminal. The gasket and the connecting plate are used to secure the size, and the assembled sealing plate is deformed outward when the pressure inside the battery rises, and the sealing part is easily loosened.

[0007]

According to this structure, the positive electrode terminal made of an organic electrolyte resistant metal rivet press-fitted into the through hole in the central portion of the sealing plate is directly welded to the connecting plate for connecting the lead plate. It is connected and fixed, and electrical conduction and fixing to the sealing plate are performed at the same time. As a result, unlike the conventional method of crimping and fixing the rivet and at the same time ensuring electrical continuity, it will not be affected by loosening of the rivet caulking or oxide film on the rivet surface in a cold atmosphere or long-term use. It is possible to obtain a highly reliable battery with stable internal resistance for a long period without increasing the resistance of the terminal portion.
Further, the number of parts of the assembled sealing plate is reduced from 5 to 3 as compared with the conventional example, and the work process is simplified and the workability is improved because the rivet caulking process is unnecessary. Furthermore, since the heat-treated gasket is used, there are no molding flaws, and even if the battery is stored there is no dimensional change in the gasket. Since the assembly sealing plate is used, the gas inside the battery is released to the outside when the sealing portion is loosened, and thus the battery has an explosion-proof action to prevent the battery from being destroyed.

[0008]

Embodiments of the present invention will be specifically described below with reference to FIGS.

FIG. 3 is a sectional view of a battery using the assembled sealing plate of the present invention. 1 is a sealing plate made of polypropylene resin, 2
Is a T-shaped positive electrode terminal made of stainless steel, 3 is a disc-shaped connecting plate made of titanium, 8 is a battery case made of nickel-plated iron that also serves as a negative electrode terminal, and has an annular groove protruding inward. I have it. Reference numeral 9 denotes a metal positive electrode lead plate, one end of which is connected to the connecting plate 3 and the other end of which is connected to the positive electrode plate 10. The positive electrode plate 10 is formed by coating a positive electrode mixture containing fluorocarbon as an active material on a metal net, and faces the negative electrode plate 12 made of lithium via a separator 11 made of polypropylene non-woven fabric. As the organic electrolyte, γ-butyrolactone in which a lithium salt such as lithium borofluoride is dissolved is used. The assembled sealing plate composed of the sealing plate 1, the positive electrode terminal 2, and the connecting plate 3 is the battery case 8
The battery case 8 is placed on the annular groove portion and is sealed by curling the tip of the battery case 8 inward.

Next, the assembled sealing plate will be described in detail. FIG. 1 is a sectional view of the assembled sealing plate of the present invention, and FIG. 2 is an exploded view thereof. Reference numeral 1 denotes a disc-like member having a hole portion at the center, and 13
Sealing plate made of polypropylene resin heat-treated at 0 ° C (outer diameter 15.5 mm, thickness 2 mm), 2 is stainless steel (SU
S444) T-shaped positive electrode terminal, which comprises a cylindrical head portion 2a having a diameter larger than the diameter of the opening of the sealing plate and a cylindrical lower shaft portion 2b having a diameter smaller than the head portion 2a. The lower shaft portion 2b is press-fitted into the opening portion in the central portion of the sealing plate so as to be on the outside of the battery. 3 is a disc-shaped titanium connecting plate (outer diameter 10 m
m, thickness 0.3 mm), and the bottom surface of the positive electrode terminal 2 is fixed to the center thereof by spot welding. The outer diameter of the lower shaft portion 2b of the positive electrode terminal is less than that of the inner diameter of the opening portion of the sealing plate 1.
It is made larger from 05mm to 0.5mm. The reason for this is that the optimum conditions will vary somewhat depending on the material of the sealing plate used, but if the dimensional difference is less than 0.05 mm, the sealing plate 1 and the positive electrode terminal 2 will not fit easily and liquid leakage will easily occur. ．
This is because if the thickness is 5 mm or more, the positive electrode terminal 2 is pressed into the sealing plate 1 and the sealing plate made of resin is cracked during storage and is easily broken. Further, the tip of the lower shaft portion 2b of the positive electrode terminal is gradually tapered so as to facilitate work when press-fitting into the opening of the sealing plate 1, and the outer diameter of the tip is the inner diameter of the opening. Is smaller than. As the material of the positive electrode terminal 2 and the connecting plate 3, SUS444 and titanium were used in this example, but in addition to this, SU having excellent corrosion resistance in an organic electrolyte solution is used.
S434, SUS316, SUS304, SUS430
Stainless steel such as can also be used. It is more preferable that the stainless steel contains molybdenum in an amount of 0.75 to 4% by weight and has excellent corrosion resistance. As the positive electrode terminal 2, a nickel-plated surface whose contact resistance is electrically reduced can be used.

A heat-treated thermoplastic resin is used as the material of the sealing plate 1 in order to remove molding strain by heat treatment so as to improve liquid leakage resistance at high temperature, and to use crystals such as polyolefin. This is because in the case of a volatile resin, the strength of the sealing plate is improved by heat treatment, and stable sealing is performed without deforming the sealing plate. Although the heat treatment temperature varies depending on the type of resin used for the sealing plate, it is generally effective to perform the heat treatment in the range of 100 ° C. or higher to less than the melting point of the resin. Further, the effect is exhibited if the heat treatment time is 30 minutes or more, but the range of 1 to 48 hours is preferable, and the heat treatment may be performed for a longer time as long as the sealing plate does not deteriorate. In the examples, a polypropylene sealing plate that has been heat-treated at 130 ° C. for 12 hours is used, but in the case of polypropylene, a liquid leakage resistance effect appears at 100 ° C. or higher, and in particular, a sealing plate in which the positive electrode terminal lower shaft portion 2b is press-fitted. Effective in preventing liquid leakage from the opening. But 160
On the contrary, when the temperature is higher than 0 ° C, the resin strength becomes brittle, so that cracks may be generated from the through holes of the sealing plate into which the positive electrode terminal is press-fitted and liquid leakage may easily occur. Another feature of the assembled sealing plate of the present invention is that it has an explosion-proof effect. If the internal pressure of the battery rises or heat is applied due to some external factor, the assembled sealing plate will be deformed outward, and the thickness of the sealing plate and connecting plate and connecting plate outer diameter / The ratio of the outer diameter of the sealing plate is adjusted. Regarding the thickness of the sealing plate, the thicker the sealing plate outer edge portion, which is crimped by the tip of the battery case 8, the better the liquid leakage resistance, and the thinner the sealing plate is, the better the deformability when the battery internal pressure rises. There is. Therefore, the thickness satisfying both characteristics is 1.0 to 4.
It is preferably in the range of 0 mm.

As for the connecting plate 3, the lower end surface of the lower shaft portion of the positive electrode terminal 2 is welded to the central portion thereof, and the positive electrode lead plate 9 is welded to the peripheral portion thereof. As the outer diameter of the connecting plate becomes closer to the outer diameter of the sealing plate, the deformation of the sealing plate is prevented when the internal pressure of the battery rises.
It is necessary to set the ratio of the outer diameter of the sealing plate to 0.85 or less. If it is more than that, the pressure resistance of the assembled sealing plate becomes high, and the explosion-proof effect is hard to work. The thickness of the connecting plate is also related to the explosion-proof effect of the assembled sealing plate, and must be 0.5 mm or less to follow the deformation of the sealing plate when the internal pressure of the battery rises. Further, in order to maintain stable welding strength, the thickness of the connecting plate needs to be 0.1 mm or more. Therefore, it is necessary that the thickness satisfying both of these characteristics is in the range of 0.1 to 0.5 mm. There are methods such as laser welding and resistance welding for spot welding the positive electrode terminal 2 and the connecting plate 3, but laser welding having high welding strength and small variation is preferable.

In the construction of the assembled sealing plate of the present invention, the positive electrode terminal 2 and the connecting plate 3 are connected by spot welding, and the connecting plate 3 is also connected.
Since it is spot-welded to the positive electrode lead plate 9, electrical continuity is ensured. Further, the rivet-shaped positive electrode terminal is fixed by press fitting into the sealing plate 1 and welding with the connecting plate 3, and is not fixed by crimping as in the conventional case. Therefore, even if the polypropylene sealing plate 1 shrinks in a cold atmosphere or an oxide film is formed on the surface of the positive electrode terminal for a long period of use, it is not affected at all and the electrical continuity is stably maintained. You can

In this example, a battery using fluorocarbon as the positive electrode active material has been described, but it can be applied to a battery using a metal oxide such as manganese dioxide or a chloride as the positive electrode active material.

Next, the internal resistance of the battery using the assembled sealing plate of this example and the conventional example was measured immediately after the production and one month after the heat cycle test. The heat cycle test is conducted in a temperature range of -10 ° C to 60 ° C for one cycle of 8 hours.

[0016]

[Table 1]

Further, (Table 2) shows the discharge duration when these batteries were discharged to 2.5 V at a resistance of 1 kΩ at 20 ° C.

[0018]

[Table 2]

[0019]

As is apparent from the above description, the lower shaft of the organic electrolyte resistant T-shaped positive electrode terminal is inserted into the central opening of the heat-treated sealing plate, and the head of the T-shaped positive electrode terminal is inserted. Is placed outside the battery, and an organic electrolytic solution resistant connecting plate for connecting the lead plate is welded to the bottom surface of the positive electrode terminal to ensure electrical continuity of the sealing portion and fixing of the positive electrode terminal. And when the pressure inside the battery rises,
The assembled sealing plate is deformed outward, the sealing part is loosened, gas inside the battery is released to the outside, and damage to the battery is prevented in advance. As a result, the increase in internal resistance is small in a wide range from low temperature to high temperature, the discharge performance after storage is good, the manufacturing process can be simplified, and the workability is improved. In addition, it also has the effects of excellent liquid leakage resistance and safety.

[Brief description of the drawings]

FIG. 1 is a sectional view of an assembled sealing plate according to an embodiment of the present invention.

FIG. 2 is an exploded view of the assembly sealing plate.

FIG. 3 is a cross-sectional view of a cylindrical battery using the assembly sealing plate.

FIG. 4 is a sectional view of a conventional assembled sealing plate.

FIG. 5 is a cross-sectional view of a cylindrical battery using the assembly sealing plate.

[Explanation of symbols]

 1 Sealing Plate 2 Positive Terminal 2a Positive Terminal Head 2b Positive Terminal Lower Shaft 3 Connecting Plate 4 Rivet 5 Lower Washer 6 Upper Washer 7 Cap 8 Battery Case 9 Positive Lead Plate 10 Positive Plate 11 Separator 12 Negative Plate

Claims (1)

[Claims] 1. A battery for sealing an opening of a battery case, wherein the sealing part has a disc shape and has an opening part in a central part, and is a heat-treated electrolytic solution resistant thermoplastic resin sealing plate. A T-shaped lower shaft portion of which is composed of a positive electrode terminal inserted into the opening of the sealing plate and a disc-shaped metal connecting plate for connecting a positive electrode lead plate welded to the lower end surface of the lower shaft portion of the positive electrode terminal. The thermoplastic resin sealing plate is a disc-shaped polypropylene resin sealing plate having a thickness in the range of 1.0 to 4.0 mm, which is heat treated at 100 to 160 ° C., and is a connecting plate for connecting the positive electrode lead plate. Is a disc-shaped corrosion-resistant metal having a thickness of 0.1 to 0.5 mm, and the sealing plate has a connecting plate outer diameter / sealing plate outer diameter ratio of 0.85 or less. battery.