JPH11354091A - Battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain electrical conductivity between a dish-like sealing plate and a cap well, even under stress such as temperature cycles or the like by crimping and fixing a valve element and a cap by bending inward the opening end of the dish-like sealing plate, and electrically connecting the bent part of the dish-like sealing plate to the cap. SOLUTION: A bent part of a dish-like sealing plate is preferably welded to and electrically connected to a cap. After a disc-like valve element 4 is inserted into and mounted to the dish-like sealing plate 3 having a valve hole 3a and the valve hole 3a is closed, a ring-like stiffening plate 5 and the cap 6 having a gas vent hole 6a at its projecting part are inserted and mounted on the upper surface of the valve element 4, and the valve element 4, the stiffening plate 5 and the cap 6 are fixed by crimping the peripheral opening of the dish-like sealing plate 3 inward with a die. The bent part 3c is electrically connected to the cap 6. If the electrical conductivity is secured by welding, the increase in the contact resistance in the sealing plate can be prevented and nonconformities such as rapid increase in the inside resistance of the battery and degradation of the battery voltage can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery provided with a sealing plate and a method for producing the battery.

[0002]

2. Description of the Related Art A battery such as a nickel-metal hydride storage battery or a lithium ion battery has a purpose of closing a battery case accommodating a power generating element composed of a positive electrode, a negative electrode and an electrolyte, and discharging gas generated inside the battery case. A dish-shaped sealing plate is provided at the opening of the battery case. As such a dish-shaped sealing plate, those having various structures are known.

[0003] As an example, there is provided a valve body having a valve hole on the bottom surface protruding toward the battery case, and closing the valve hole from the inside of the dish-shaped sealing plate. A dish-shaped sealing plate sandwiched between a peripheral edge and a flange portion of a cap having a gas vent hole in a protruding portion and having an open end portion of the dish-shaped sealing plate bent inward and fixed by caulking is provided. Can be Such a dish-shaped sealing plate is caulked together with a battery case via a gasket made of a resin such as polypropylene, and provided in an opening of the battery case (for example, Japanese Patent Laid-Open No. 1-15115).
No. 4).

A dish-shaped sealing plate having another structure is provided with a valve body having a valve hole on the bottom surface protruding toward the battery case and closing the valve hole from the inside of the dish-shaped sealing plate. The valve body is fixed by caulking by bending the open end of the dish-shaped sealing plate inward via the reinforcing plate, and a cap having a gas vent hole in the convex portion is mounted on the top surface of the swaged dish-shaped sealing plate. Is known (for example, see Japanese Patent Application Laid-Open No. 7-18302).
No. 0).

[0005]

However, in the dish-shaped sealing plate having the above-described structure, electrical conduction between the dish-shaped sealing plate and the cap is performed by caulking the opening of the dish-shaped sealing plate. The cap is held by contact between the bent portion and the cap, or the compression force of the caulking resin gasket between the dish-shaped sealing plate and the cap. In such a structure, if the contact force is reduced due to deterioration over time or mechanical strength of the gasket due to temperature cycling or thermal shock, the pressure contact between the dish-shaped sealing plate and the cap is weakened. As a result, the electrical continuity between the sealing plate and the cap becomes incomplete, causing problems such as a sharp increase in battery internal resistance and a decrease in battery voltage.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a power generation element comprising a positive electrode, a negative electrode and an electrolytic solution in a battery case, and has a dish-shaped sealing plate at an opening thereof. In the battery, a valve body that closes a valve hole provided on a bottom surface protruding from the battery case side of the dish-shaped sealing plate from the inside thereof,
A cap having a gas vent hole on the convex portion is placed, and the valve body and the cap are fixed by bending the peripheral edge of the dish-shaped sealing plate inward and caulking. The cap is electrically connected to the bent portion bent toward the upper side.

[0007]

According to the first aspect of the present invention, the dish-shaped sealing plate has a valve hole on the bottom surface protruding toward the battery case,
And a valve body for closing the valve hole from the inside of the dish-shaped sealing plate;
A ring-shaped reinforcing plate is provided on the upper surface of the valve body, and a cap having a gas vent hole in the convex portion is provided. The valve body, the reinforcing plate, and the cap are formed by bending an opening end of the dish-shaped sealing plate inward and caulking. After fixing, the bent front end portion of the dish-shaped sealing plate and the upper surface portion of the cap are electrically connected by a welding method or the like.

[0008] In another configuration, the dish-shaped sealing plate has a valve hole on the bottom surface protruding toward the battery case, and the valve hole closes the valve hole from the inside of the dish-shaped sealing plate. If necessary, a ring-shaped reinforcing plate is provided on the upper surface, and the valve body and the reinforcing plate are fixed by bending the open end of the dish-shaped sealing plate inward and crimping, and then crimping the plate-shaped plate. A cap having a gas vent hole on a convex portion is placed on the upper surface of the sealing plate, and the bent portion of the dish-shaped sealing plate and the peripheral portion of the cap are electrically connected by welding or the like. is there.

As a welding method for providing electrical conduction, a method for manufacturing a sealing plate provided with a step of welding at least one portion of a bent portion of a dish-shaped sealing plate and a swaged cap by laser welding is used. A step of welding at least one portion of the outer peripheral portion of the bent portion of the sealing plate and the outer peripheral portion of the cap placed on the upper surface of the dish-shaped sealing plate by laser welding.

Since electrical conduction between the cap of the dish-shaped sealing plate and the cap can be ensured by welding, the mechanical strength of the resin gasket deteriorates due to repeated thermal expansion and contraction due to a load such as a rapid temperature cycle, and the caulking portion The electrical conduction failure caused by the deterioration of the contact pressure between metals is eliminated, so that the contact resistance of the sealing plate can be prevented from increasing, and the problems such as a sudden increase in the internal resistance of the battery and a decrease in the battery voltage can be prevented. A battery and a battery sealing plate can be provided.

[0011]

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a cylindrical lithium battery to which a sealing plate according to a first embodiment of the present invention is applied. In this figure, A is a power generation element group, and the positive electrode is composed mainly of graphite fluoride, manganese dioxide, etc., to which a conductive material and a binder are added. Metallic lithium is used for the negative electrode. An electrode group in which the positive electrode and the negative electrode are spirally formed through a separator made of a polypropylene nonwoven fabric or a microporous film, and propylene carbonate, 1,2-dimethoxyethane, γ-butyrolactone are used as electrolytes in the electrode group. Solvent alone or
Alternatively, LiBF4, LiBF
A power generation element is formed by impregnating a material in which ClO4 or the like is dissolved.

Reference numeral 1 denotes a battery container, in which a current collector lead 2 of metallic lithium, which is a negative electrode active material of the electrode plate group, is welded to the inner peripheral surface by spot welding to serve also as a negative electrode terminal. As the material, an electrolytic solution-resistant stainless steel material having a thickness of about 0.3 mm, or corrosion-resistant plated iron is used. B is an assembled sealing plate according to the present invention, in which the bent portion of the dish-shaped sealing plate and the swaged cap are electrically connected. In the figure, reference numeral 7 denotes a gasket attached to the peripheral edge of the dish-shaped sealing plate, and reference numeral 8 denotes a positive electrode current collecting lead.

The structure of the assembled sealing plate according to the embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 2, a disc-shaped valve body 4 is inserted and placed in a dish-shaped sealing plate 3 having a valve hole 3a to close the valve hole 3a. A ring-shaped reinforcing plate 5 and a cap 6 having a gas vent hole 6a in a convex portion are inserted and placed, and the valve body 4, the reinforcing plate 5 and the cap 6 are placed inside the peripheral opening 3b of the dish-shaped sealing plate 3 inside. It is caulked with a mold and fixed. This is formed from the step of electrically connecting the bent portion 3c of the dish-shaped sealing plate to the swaged cap 6.

Alternatively, in the above-described step, the bent tip portion 3d of the dish-shaped sealing plate and the upper surface portion of the cap 6 are welded by laser welding, more specifically, using a YAG laser to form the tip of the dish-shaped sealing plate. The contact portion C1 with the upper surface portion of the cap is welded to at least one place to be electrically connected, and
This completes the assembled sealing plate shown in FIG.

(Embodiment 2) Another embodiment of the sealing plate of the present invention will be described. FIG. 4 is a cross-sectional view of a cylindrical lithium battery to which a sealing plate according to Example 2 is applied, and has the same configuration as that of FIG. 1 except for the configuration of the sealing plate. B is a sealing plate having a structure in which the bent portion of the dish-shaped sealing plate and the cap placed on the upper surface of the sealing plate according to the present invention are electrically conductive,
As shown in FIGS. 5 and 6, a disc-shaped valve body 4 is inserted and placed in a dish-shaped sealing plate 3 having a valve hole 3a, and the valve hole 3a is closed. The ring-shaped reinforcing plate 5 is inserted and placed on the upper surface of the plate, and the valve body 4 and the reinforcing plate 5 are caulked by using a metal mold with the peripheral opening 3b of the dish-shaped sealing plate 3 inwardly to fix the valve body. . Next, a cap 6 having an outer diameter equal to or slightly smaller than the outer diameter of the dish-shaped sealing plate on the upper surface of the swaged dish-shaped sealing plate, and having a gas vent hole 6a in the convex portion is placed. Bent outer peripheral portion 3e of sealing plate and outer peripheral portion 6b of cap 6
Specifically, the contact portion C2 is formed by a process of welding at least one portion with a YAG laser by a laser welding to make the portion electrically conductive.

(Comparative Example 1) A cylindrical lithium battery using a sealing plate in which a dish-shaped sealing plate and a cap were not laser-welded as the sealing plate in Example 1 was produced.

(Comparative Example 2) A cylindrical lithium battery was produced in Example 2 using a sealing plate in which a dish-shaped sealing plate and a cap were not laser-welded as the sealing plate.

Each of the thus obtained 1000 batteries of Examples 1 and 2 and Comparative Examples 1 and 2 was allowed to stand at 80 ° C. for 1 hour, and then left at -40 ° C. for 1 hour.
One hour of standing for one hour, this temperature cycle is 500
A test was conducted to examine changes in battery characteristics due to temperature changes by repeating the cycle. Table 1 shows the results of measuring the number of batteries whose internal resistance increased after the implementation compared to before the implementation.

[0021]

[Table 1]

As is clear from the table, the battery manufactured by the method of the present invention employs a structure in which the dish-shaped sealing plate and the cap are completely electrically connected to each other, so that the battery can be subjected to stress such as temperature cycling. It is possible to provide a battery that can ensure electrical continuity between the dish-shaped sealing plate and the cap even when the battery is placed in the battery.

[0023]

As described above, the battery of the present invention employs a structure in which the dish-shaped sealing plate and the cap are electrically connected to each other, so that the battery can be placed under stress such as temperature cycling. In addition, it is possible to provide a battery that can maintain good electrical conduction between the dish-shaped sealing plate and the cap.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a cylindrical lithium battery to which a sealing plate according to a first embodiment is applied.

FIG. 2 is an exploded sectional view at the time of assembling the sealing plate in the first embodiment.

FIG. 3 is a cross-sectional view of the sealing plate according to the first embodiment.

FIG. 4 is a cross-sectional view of a cylindrical lithium battery to which a sealing plate is applied in Example 2.

FIG. 5 is an exploded cross-sectional view when assembling a sealing plate according to a second embodiment.

FIG. 6 is a cross-sectional view of a sealing plate according to a second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 battery container 2 negative electrode current collector lead 3 dish-shaped sealing plate 3 a valve hole 3 b peripheral edge of dish-shaped sealing plate 3 c bent portion of dish-shaped sealing plate 3 d bent tip of dish-shaped sealing plate 4 valve body 5 Reinforcement plate 6 Cap 6a Gas vent hole 6b Outer peripheral portion of cap 7 Gasket 8 Positive electrode current collecting lead C1 Laser welded part C2 Laser welded part A Power generation element group B Sealing plate

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Takayuki Tanahashi 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A battery in which a power generation element including a positive electrode, a negative electrode, and an electrolyte is housed in a battery case, and an assembly sealing plate is arranged in an opening of the battery case, wherein the assembly sealing plate is an inner surface of the battery case. A battery provided with a valve hole on the bottom surface protruding to the side, a valve body for closing the valve hole from the inside of the dish-shaped sealing plate, and a cap having a gas vent hole on the convex portion, wherein the valve body and A battery, wherein the cap is fixed by caulking by bending an open end of the dish-shaped sealing plate inward, and furthermore, the bent portion of the dish-shaped sealing plate is electrically connected to the cap. 2. The battery according to claim 1, wherein the bent portion of the dish-shaped sealing plate and the cap are welded to each other to establish electrical conduction. 3. A power generation element comprising a positive electrode, a negative electrode, and an electrolyte is provided in a battery case, a dish-shaped sealing plate is provided at an opening of the battery case, and the battery case projects from the dish-shaped sealing plate toward the battery case. A method for producing a battery comprising a valve having a valve hole on a bottom surface and closing the valve hole from the inside of a dish-shaped sealing plate, wherein the valve body has an opening end of the dish-shaped sealing plate inward. After being bent and caulked and fixed, a cap having a gas vent hole in a convex portion is placed on the upper surface of the caulked and fixed dish-shaped sealing plate, and the bent portion of the dish-shaped sealing plate and the cap are further fixed. A method for producing a battery, comprising electrically conducting. 4. The method for producing a battery according to claim 3, wherein the bent portion of the dish-shaped sealing plate is welded to the cap to electrically conduct.