JP2003242938A - Sealed rectangular storage battery, and manufacturing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed rectangular storage battery with small size and high capacity of which, variation of an external case caused by swelling, is restrained, and to provide a manufacturing method of the same. <P>SOLUTION: For the sealed rectangular storage battery, a variation quantity of the external case caused by swelling generated when inner pressure of the battery is increased, is reduced by installing oblong and concave-shaped curved wires 3 parallel with a long side, at the inside of two sides constructing the end parts of long sides of two main surfaces 1A facing each other and having largest area among all side surfaces of the rectangular external case, excluding the neighboring area of two sides constituting the end parts of short sides. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery, in particular, a closed prismatic storage battery such as a nickel-hydrogen storage battery and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the development of portable devices using batteries has been remarkable, and the commercialization of mobile phones, portable audio devices, etc. has been actively developed. For nickel-hydrogen storage batteries and lithium-ion batteries used as driving power sources for these devices, demands for higher capacity, smaller size and lighter weight are increasing year by year. In order to meet these requirements, the battery is downsized to save space,
A small battery in which the shape of the outer can is changed from the conventional cylindrical type to a square type is often used.

Such a small prismatic battery is usually manufactured as follows. First, the electrode plate group is inserted into a rectangular bottomed outer can. The electrode plate group is formed by stacking a positive electrode plate, a separator, and a negative electrode plate. The outermost negative electrode plate is connected to an outer can, and the positive electrode plate is connected to a positive electrode terminal provided on a rectangular lid body electrically isolated by an insulating member. After that, the electrolytic solution is injected into the outer can, the peripheral portion of the lid is attached to the open end of the outer can, and the periphery is laser-welded and sealed.

The battery thus manufactured is required to have a low weight per capacity and a volume as small as possible. As a technique for reducing the size and weight of a battery and increasing its capacity, a technique for thinning a part of an outer can of a cylindrical battery is disclosed in Japanese Patent Laid-Open No. 57-96455. This technique utilizes the fact that the cylindrical body has an ideal shape against pressure and is extremely tough, and the wall thickness of the body of the cylindrical outer can is made thinner than the bottom. However, in the prismatic battery, since each surface is flat, deformation due to pressure is likely to occur, and it is difficult to reduce the thickness of the outer can due to its structure.

Conventionally, as a method for reducing the deformation of the rectangular outer can due to the pressure, the battery described in JP-A-5-13054 is known. This is shown in FIG.
As shown in (b), the main surface 1C having the widest area in the outer can, with its central portion curved inward of the peripheral portion toward the inside of the battery, has a flat main surface. ,
It is said that when the battery internal pressure rises due to overcharging or the like, the amount of outward bulging and deformation is small, and when the internal pressure of the can is normally reduced due to gas disappearance or the like, the resilience is excellent.

[0006]

Due to the recent demand for smaller size, lighter weight, and higher capacity for batteries, the outer can is made thin and the effective volume inside the can is maximized to be used for accommodating electrode plates. Required to do so. However, the deformation pressure resistance of the rectangular outer can depends on the material composition and the thickness of the can. For example, when the thickness of the outer can is further reduced for the purpose of increasing the capacity, the outer can easily deforms even if the battery internal pressure is the same, and the amount of swollen deformation of the outer can increases.

In the battery having the structure in which the main surface of the rectangular outer can thus far is curved inward of the battery, when the amount of pressure deformation becomes large and the limit of elastic recovery is approached, each surface becomes flat. Compared with this, the resilience becomes worse. That is, when the battery internal pressure rises, a force is applied to the central portion of the main surface 1C with the peripheral edge as a fulcrum, and the central portion of the outer can main surface 1C is displaced to the outside of the battery. At this time, stress concentrates also on the peripheral edge, and the peripheral edge gradually opens. When the internal pressure of the battery further rises, the central portion of the main surface 1C becomes CC-C in FIG.
As shown in the cross-sectional view of the line, the battery is bulged outward.

At this time, the battery of this structure has a large amount of deformation with respect to a flat main surface, and the restoring elasticity to return to the original is not effective, so that the original shape is obtained even if the internal pressure of the battery is reduced. It is difficult to return to. Therefore, after the internal pressure of the battery rises and the outer can is largely deformed, the battery performance is deteriorated even if the internal pressure decreases. This is because the outer space of the outer can becomes wider than the calculated value and the group pressure becomes ineffective.

[0009]

In order to solve this problem, the present invention provides a storage battery in which an electrode plate group consisting of a positive electrode plate, a negative electrode plate, and a separator is sealed in a rectangular outer can. The inside of each of the two long sides of the two main surfaces facing each other, which have an area of, and the long concave sides are parallel to the long sides, except for the vicinity of the two short sides. One piece is formed toward the inside of the battery to substantially increase the pressure resistance against bulging deformation of the main surface to the outside.

By forming one long and narrow concave bent line parallel to the long side toward the inside of the battery on the main surface of the outer can, the ends along the long side are substantially separated from each other. While the pressure resistance is increased, the distance (span) between the main surfaces sandwiched by the two elongated concave bending lines is shortened, and even if the internal pressure of the can increases, it does not easily deform, and even if it deforms. The amount of deformation is small. Further, when the internal pressure of the can is normally decreased due to the disappearance of gas or the like, the resilience due to the elastic restoring force is excellent.

Further, the sealed prismatic storage battery of the present invention is manufactured through the following steps.

The electrode plate group in which the positive electrode plate, the separator, and the negative electrode plate are laminated is placed in a bottomed rectangular outer can having a rectangular opening, and the plane of the electrode plate and the main surface of the outer can are parallel to each other. To insert.

After accommodating the electrode plate group inside, a step of sealing the opening of the rectangular outer can with a rectangular lid.

Inside the outer can, each of the two long sides of the two main surfaces facing each other has the largest area,
A step of pressing the elongated bent lines parallel to the long sides toward the inside of the battery one by one except for the vicinity of the two upper and lower ends which are the short sides.

However, it is not necessary to specify the order of the above steps depending on the type of battery, especially the type of electrode plate.
After the above process, the battery is manufactured through the process, that is, the outer can is pressed after inserting the electrode plate group, or the battery is manufactured through the process after the above process, That is, it is also possible to insert the laminated electrode plate group into an outer can in which a concave bent line is pressed along the long side end of the main surface toward the inside of the battery.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 (a) is a front view of a sealed prismatic battery of the present invention, and FIG. 1 (b) is a schematic sectional view taken along line AA.

According to the present invention, an electrode group in which a positive electrode plate, a separator and a negative electrode plate are laminated is housed inside a rectangular rectangular outer can 1, and the upper part of the outer can 1 is sealed by a sealing plate 2. A storage battery, which has the largest area in the outer can 1 and has two major sides 1A facing each other, which are the long sides of the two ends, and the inside of each of the two sides of the upper and lower edges that are the short sides. Except for, the long and narrow concave bent lines 3 are formed one by one toward the inside of the battery.

The concave bent line 3 is parallel to the long side at a position of 5 to 25% of the short side length from the long side end toward the center, except for 0.1 mm or less from the short side end. It is desirable that the position that is most inward of the battery is 0.1 mm to 0.5 mm.

In the prismatic storage battery, the pressure inside the battery rises due to overcharging or the like. When the internal pressure increases, uniform pressure is applied to each surface of the rectangular outer can 1 from the inside. At this time, the main surface 1A having the largest area is most easily deformed.

According to the present invention, the two long sides of the main surface 1A having the largest area in the outer can, the inside of each of the two sides.
Except for the vicinity of the upper and lower ends 2 which are short sides, one elongated concave bending line 3 parallel to the long side was provided toward the inside of the battery. And outer can 1
Becomes extremely strong against the internal pressure, the area receiving the pressure can be reduced in a pseudo manner, and the deformation amount due to the increase in the internal pressure of the can can be reduced.

In the sealed prismatic storage battery of the present invention, when the internal pressure of the battery rises and each surface of the outer can is deformed, the main surface 1A of the outer can 1 is long as shown in FIG. 1 (b). Deformation is performed with the bending line 3 facing the inside of the elongated concave battery near the side as a fulcrum.

Therefore, when the present invention and the conventional example are compared with an outer can having the same material and wall thickness, the fulcrum of deformation of the battery of the present invention is moved toward the center of the battery and the area of the main surface is changed. Is substantially smaller, the deformation due to pressure can be made significantly smaller than in the conventional example.

Further, in the prismatic storage battery of the present invention, it is not necessary for the central portion of the main surface 1A to be curved toward the inside of the battery with respect to the position where the bent portion is most inside the battery, and unlike the conventional battery. It has the characteristics that the bending direction does not reverse inside and outside due to the increase of the internal pressure, and the restoring property when the internal pressure of the can is normally reduced is excellent.

The manufacturing method of the sealed rectangular storage battery of the present invention is as follows.
The process of inserting the electrode plate group consisting of the positive electrode plate, the separator, and the negative electrode plate into a rectangular outer can with a bottom, the step of sealing the opening of this outer can with a lid, and having the largest area in the outer can. , Inside each of the two opposite ends 2 sides that are the long sides of the two main surfaces 1A facing each other, except for the vicinity of the two ends that are the short sides, an elongated concave bending line parallel to the long sides is formed inside the battery. And a step of press-forming one by one.

Here, the concave bending line is located at a position 5 to 25% of the length of the short side from the end of the long side toward the center and at the long side except for 0.1 mm or less from the end of the short side. They are parallel, and the position where they are most inside the battery is 0.1 mm to 0.
It is preferably 5 mm.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, specific examples of the present invention will be described with reference to the drawings.

A sealed prismatic storage battery is manufactured by the following steps.

(Example 1) A nickel-plated SPCE steel plate was drawn to obtain a rectangular bottomed outer can 1 having a rectangular shape with an open end dimension of 5 x 15 mm, a depth of 30 mm and a wall thickness of 0.25 mm. Create.

An electrode plate group is produced by stacking three nickel positive electrode plates and four hydrogen storage negative electrode plates with a polypropylene separator interposed therebetween.

In this electrode group, the main surface of the electrode plate is the outer can 1.
It is housed in the outer can 1 so as to be parallel to the main surface 1A.

After the positive electrode lead is connected to the positive electrode terminal provided in the center of the rectangular sealing plate 2 so as to be insulated and isolated, and the negative electrode lead is connected to the inner surface of the can, the sealing plate 2 is attached to the open end of the outer can 1. Then, the periphery thereof was laser-welded to form a closed prismatic nickel-hydrogen storage battery.

On the two main surfaces 1A of the outer can 1, at a position 0.8 mm from the ends of the long sides toward the center of the shaft, as shown in FIG.
As shown in the side view of the battery in (a) and the cross-sectional view taken along the line BB in (b), the chevron-shaped protrusions 5 having a width of 0.8 mm, a height of 0.25 mm, and a length of 25 mm are provided on the press punch 4. The press punch 4 is pressed and moved so as to oppose in parallel with the long side of the surface to press the two main surfaces 1A. By this processing, in the vicinity of the long side of the main surface 1A of the outer can, as shown in the battery front view of FIG. An embodiment of the present invention in which a concave bending line 3 that is 0.2 mm inside from the inner surface is provided, and a bulging curved portion 6 is formed on the outside that gently curves toward the center of the main surface from this bending line 3 The sealed rectangular nickel-hydrogen storage battery in No. 1 was constructed.

Example 2 As shown in FIG. 2, at the position 0.8 mm from the long side end of the main surface 1A of the outer can 1 toward the axial center, a width 0.8 mm provided on the punch 3, The mountain-shaped protrusions 5 having a height of 0.25 mm and a length of 25 mm are opposed to each other in parallel with the long sides of the main surface, and the press punch 4 is moved under pressure to press the two main surfaces 1A. By this processing, near the long side of the main surface 1A of the outer can,
A concave bending line 3 having a length of 25 mm and having a depth that most penetrates the inside of the battery inward is 0.2 mm from the inner surface of the original main surface is provided, and the bending line is a gradual point toward the center of the main surface. A bulging curved portion 6 can be formed on the outwardly curved side.

An electrode plate group 1 is manufactured by laminating three nickel positive electrode plates, four hydrogen storage negative electrode plates and a separator.

The laminated electrode plates are press-fitted into the pressed outer can 1 using a jig.

After the positive electrode lead is connected to the positive electrode terminal provided in the center of the rectangular sealing plate 2 so as to be insulated and isolated, and the negative electrode lead is connected to the inner surface of the can, the sealing plate 2 is attached to the open end of the outer can 1. Then, the periphery thereof was laser-welded to form a sealed rectangular nickel-hydrogen storage battery of Example 2 of the present invention.

(Comparative Example 1) As a comparative example 1, a sealed prismatic nickel-hydrogen storage battery of a comparative example 1 having a planar main surface, which was manufactured through the steps from Example 1 was manufactured.

(Comparative Example 2) As Comparative Example 2, after the steps from Example 1 were performed, as shown in the battery front view of FIG. 3A and the sectional view taken along line CC of FIG. The outer can 1 was pressed with a press punch for a comparative example having a structure in which the part bulges out to the outermost side, and the central portion of the main surface is curved 0.2 mm toward the inside of the battery. Type nickel-hydrogen storage battery was produced.

Four types of closed prismatic nickel-hydrogen storage batteries of Examples 1 and 2 and Comparative Examples 1 and 2 were tested by the following test method to measure the amount of deformation of the outer can 1.

A high pressure nitrogen gas cylinder is connected to the sealing plate of the manufactured battery.

The gas pressure supplied to the outer can is gradually increased from the atmosphere to 1 MPa.

The amount of deformation of the main surface with respect to each pressure, that is, the amount of change in the bulge of the central portion of the main surface is measured.

The supply of gas was stopped, the internal pressure of the outer can 1 was returned to atmospheric pressure, the residual deformation amount in the central portion of the main surface was measured, and the resilience of pressure deformation was measured.

From the above test results, FIG. 4 shows the relationship between the gas pressure and the bulge change amount of the central portion of the main surface. As can be seen from the measurement results of FIG. 4, the sealed rectangular storage battery of the present invention has a smaller amount of change in the outer can than the battery of Comparative Example 1 having a flat main surface, regardless of the range of the inner pressure of the can. . Further, as compared with the battery of Comparative Example 2 in which the central portion of the main surface is recessed, the amount of change in the outer can in the high voltage region is small.

Further, the internal pressure of the outer can 1 of the above test is returned to atmospheric pressure, and the residual deformation amount of the central portion of the main surface is measured,
The resilience to pressure deformation (residual deformation amount) is shown in FIG.
As is clear from FIG. 5, Examples 1 and 2 are Comparative Examples 1 and 2.
The outer can 1 is also superior in pressure restoring property. (Resilience of pressure deformation of the outer can 1 is measured by pressurizing at 1 MPa and then returning the internal pressure to atmospheric pressure to measure the amount of residual deformation.)

[0046]

As described above, the sealed prismatic storage battery of the present invention can reduce the amount of deformation when the internal pressure of the battery rises, as compared with the conventional batteries. In other words, there is a feature that the thickness of the outer can can be reduced, and it can meet the market needs for batteries that are smaller and lighter and have higher capacity.

Further, the sealed prismatic storage battery of the present invention is excellent in resilience when the internal pressure is normally lowered, so that the internal pressure temporarily rises due to overcharge and the like, and then the internal pressure drops and becomes large. The amount of change in the outer can when returning to atmospheric pressure is small, and the original shape is restored. That is, it is possible to reduce deterioration of battery performance due to expansion of the outer can and widening of the electrode spacing.

[Brief description of drawings]

FIG. 1A is a front view of a sealed rectangular nickel-hydrogen storage battery according to an embodiment of the present invention, and FIG. 1B is a schematic cross-sectional view of the battery taken along the line AA.

FIG. 2A is a side view of the battery showing a press-molding process of the battery according to the embodiment of the present invention, and FIG. 2B is a schematic cross-sectional view of the battery taken along the line BB.

3A is a front view of a sealed rectangular nickel-hydrogen storage battery in a conventional example, FIG. 3B is a schematic cross-sectional view of the battery taken along the line C-C, and FIG. 3C is a C when the main surface 1C is swollen. -C line cross section

FIG. 4 is a diagram showing the amount of change in the bulge of the central portion of the main surface 1C due to the battery internal pressure

FIG. 5 is a diagram showing the resilience of the outer can when the battery internal pressure is returned to atmospheric pressure.

[Explanation of symbols]

1 exterior can 1A main surface 1C Main surface of conventional example 2 Seal plate 3 Concave bending line 4 Press punch 5 Yamagata protrusion 6 Curved part of the main surface

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroyuki Goto             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Fuminori Ozaki             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5H011 AA01 CC06 DD05 DD06 DD13                       KK01                 5H028 AA01 AA07 BB01 BB04 HH05

Claims (4)

[Claims] 1. A hermetically sealed prismatic storage battery in which an electrode group consisting of a positive electrode plate, a separator, and a negative electrode plate is hermetically sealed in a rectangular outer can, wherein the outer can has the largest area on all sides and is facing each other. Each of the two main surfaces has, on the inside of each of the two long-side end portions, one elongated curved line parallel to the long side and directed toward the inside of the battery. Storage battery. 2. The concave bending line is parallel to the long side from the short side end at a position of 5 to 25% of the short side length from the long side end toward the center, and is the most battery-oriented. The sealed prismatic storage battery according to claim 1, wherein a position where the battery is inserted inward is 0.1 mm to 0.5 mm. 3. A step of inserting an electrode plate group consisting of a positive electrode plate, a separator and a negative electrode plate into a bottomed rectangular outer can, a step of sealing the opening of the outer can with a lid, and the inside of the outer can. The longest end 2 of the two facing major surfaces with the largest area
A method for manufacturing a sealed prismatic storage battery, comprising a step of press-molding, one by one, inside each of the sides, an elongated concave bent line parallel to the long side toward the inside of the battery. 4. The concave bent line is parallel to the long side from the short side end at a position of 5 to 25% of the short side length from the long side end toward the center, and is the most battery-oriented. The method for manufacturing a sealed prismatic storage battery according to claim 3, wherein the position where the inner side is inserted is 0.1 mm to 0.5 mm.