JP2000208110A - Thin battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin battery which can reduce aspect dimension of the battery and contain a laminated electrode in an armor case made of a resin film-based laminate sheet without dead space. SOLUTION: A thin laminated electrode 4 in which a film-like or sheet-like positive electrode plate 1, a separator 3 and a negative electrode plate 2 are integrally laminated is mounted on one side of a resin film-based laminate sheet constituting an armor case 7 to be contained in electrodes containing recessed part 11 corresponding to the electrode 4. The electrode 4 is sealed in the case 7 by heat-welding the periphery where one side and another side of the laminate sheet are overlapped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat battery using a laminated sheet mainly composed of a resin film as an outer case, which is suitable for a battery, particularly a thin and flat battery such as a lithium polymer secondary battery having an electrolyte held in a polymer. It is about.

[0002]

2. Description of the Related Art A metal foil is arranged between two resin films,
A battery using a laminate sheet obtained by laminating and integrating the whole as an outer case has been known, for example, in JP-A-10-157008. In this case, the power generation element to be packaged is usually a flat laminated electrode in which a film-shaped or sheet-shaped positive electrode plate, a separator and a negative electrode plate are laminated. It is disclosed in Japanese Patent Application No. 10-28838, for example, that this is enclosed in an outer case obtained by sealing the overlapped periphery of two or a pair of laminated sheets in a bag shape by heat welding or the like. ing.

[0003]

However, in a battery using such a bag-shaped laminate sheet as an outer case, when encapsulating the flat laminated electrode in the outer case, a seal portion around the laminate sheet and the inside thereof are formed. It is inevitable that a surrounding space having a triangular cross section is formed between the stacked electrodes to be accommodated. This surrounding space becomes a useless space, and as a result, there is a problem that the outer dimensions of the battery become larger than the dimensions of the stacked electrodes.

Further, when a flat laminated electrode is inserted into an outer case, the laminated electrode can be inserted by opening a space between two or upper and lower laminated sheets that are in close contact with each other by being sealed in a bag shape. I have to make space. The work of opening the gap between the sheets and the work of inserting the laminated electrodes are troublesome, and this has caused a reduction in the production efficiency of the battery.

[0005] The present invention solves such a conventional problem, and can improve the production efficiency with a compact size.
A main object is to provide a flat battery using a laminate sheet mainly composed of a resin film as an outer case.

[0006]

In order to achieve the above object, a flat battery according to the present invention comprises a flat laminated electrode in which a film-shaped or sheet-shaped positive electrode plate, a separator and a negative electrode plate are laminated and integrated, respectively. An outer case that accommodates the laminated electrodes inside and seals the periphery of the sheet. One of the pair of laminated sheets is a flat plate portion, and the other is the laminated sheet. As a dish-shaped container portion having an electrode accommodating recess for accommodating electrodes, the periphery of both sheets is sealed by heat welding.

In order to improve the production efficiency of the battery, the laminate sheet is folded in two at the center in the longitudinal direction, one of which is a flat plate-like portion, and the other is a dish-like container portion having an electrode receiving recess. It is good to constitute from one laminate sheet.

[0008] From the viewpoint of battery compactness, the electrode accommodating recess has a rectangular shape corresponding to a flat laminated electrode having a rectangular external shape, and has a radius of curvature R at the opening corner.
The dimension of 1 is 5 mm ≧ R1 ≧ 0.5 mm, the dimension of the depth D of the container is 10 mm ≧ D ≧ 2 mm, and the dimension of the radius of curvature R2 of the bottom corner formed by the side wall and the bottom wall of the recess is 1 mm ≧
R1 ≧ 0.3 mm is preferred.

Further, the laminated sheet mainly composed of a resin film is obtained by integrating at least three layers of films, a metal foil is arranged between the first resin film and the second resin film, and they overlap each other at the time of sealing. The second resin film is preferably made of a resin having excellent heat welding properties.

The most preferred configuration of the present invention is a flat laminated electrode in which a film-shaped or sheet-shaped positive electrode plate, a separator and a negative electrode plate are laminated and integrated, and a resin film mainly composed of three or more layers of a film. An outer case, which is composed of two laminated sheets and accommodates the laminated electrodes therein and is hermetically sealed, comprises one laminated sheet, one of which is folded at the center in the length direction and one of which is flat. And the other is a dish-shaped container part having a rectangular electrode receiving recess in which the laminated electrode is stored, and the periphery of the overlapped sheets is integrated by heat welding.

According to the present invention, since the electrode sheet has a concave portion for accommodating the flat laminated electrode in the laminate sheet, a wasteful space is provided between the concave portion and the laminated electrode. Almost no, and as a result, the outer and vertical dimensions of the battery can be reduced, and a compact battery can be obtained.

Further, according to the present invention, since the flat and rectangular laminated electrode and the electrode accommodating recess provided in the laminated sheet correspond in shape, the laminated electrode can be formed with good workability by using a guide jig or the like. It can be accommodated in the recess.

Further, when an inclined surface is provided on one side of the open side of the concave portion and the inclined surface is used as a guide for inserting the laminated electrode into the concave portion, the laminated electrode can be easily accommodated in the concave portion.
Thereafter, the outer case in which the battery is sealed can be manufactured by sealing the periphery of the sheet that has been folded and overlapped, so that the battery production can be easily automated and the production efficiency can be greatly improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a lithium polymer secondary battery will be described below with reference to FIGS.

As shown in FIG. 3 and FIG. 4, a laminated electrode 4 was prepared by laminating and integrating such that a film-shaped or sheet-shaped positive electrode plate 1 and a negative electrode plate 2 face each other with a separator 3 interposed therebetween. This is configured similarly to the above-mentioned conventional example. More specifically, the positive electrode plate 1 is formed by applying a positive electrode mixture paste 1b containing lithium cobalt oxide to one surface of an aluminum sheet 1a as a current collector and drying the same, and the negative electrode plate 2 is a copper sheet 2a also as a current collector. The negative electrode mixture paste 2b containing spheroidal graphite is applied to both surfaces of the substrate and dried. The separator 3 is made of a gel-like polymer sheet holding a non-aqueous electrolyte.

The flat laminated electrode 4 is, as shown in FIG.
The mixture paste 1b of the positive electrode plate 1 above the mixture paste 2b on the upper side of the negative electrode plate 2 is opposed to the mixture paste 1b of the upper part of the negative electrode plate 2 via the separator 3, and the separator 3 is also interposed between the mixture paste 2b on the lower side of the negative electrode plate 2. The positive electrode mixture paste 1b of the positive electrode plate 1 under the lever 1 is integrated by heating and pressing in a laminated state. Aluminum sheet 1a here
As the copper sheet 2a, a lath sheet or an expanded sheet obtained by cutting a foil or a thin sheet and developing it, and a punching sheet having a large number of holes in the foil or the sheet are preferable from the viewpoint of close contact with the paste and holding thereof.

As shown in FIG. 2, a lead connecting portion 1c on the positive electrode side extends to one of the left and right directions (the vertical direction in FIG. 2) of the aluminum sheet 1a of each of the upper and lower positive electrode plates 1. It is formed. At a position deviated to the other side, a lead connection portion 2c on the negative electrode side is formed to extend from the copper sheet 2a of the negative electrode plate 2. As shown in FIG. 4, these lead connection portions are pulled out to a height position substantially coincident with the top of the flat laminated electrode 4, and a positive electrode lead 8 made of an aluminum sheet piece and a negative electrode lead 9 made of a copper sheet piece, Each is joined by ultrasonic welding S. The connection between the lead connection portion and the lead may be performed by electric resistance welding.

In this embodiment, the laminated electrode 4 has two positive electrode side lead connection portions 1c and one negative electrode side lead connection portion 2c. In order to join the leads 8 and 9 at substantially the same height, the lower positive electrode lead connection portion 1c and the lower electrode side lead connection portion 2c are bent along the container side wall as shown in FIG. ing. However, in the case of the laminated electrode 4 in which a larger number of the positive electrode plates 1 and the negative electrode plates 2 are laminated, it is necessary to overlap the respective lead connection portions 1c and 2c at a height position substantially coincident with the top of the laminated electrode 4. , More lead connection portions 1c and 2c will be bent.

The outer case 7 serves as a container for accommodating the flat laminated electrode 4 in the concave portion 11 and for holding the electrode portion impregnated with the injected electrolyte. This exterior case 7
As shown in FIG. 5 and FIG. 6, one laminate sheet 10 mainly composed of a resin film is
And the flat portions 5 located on the left and right of the bending line T
And the dish-shaped container section 6 are superimposed, and as shown in FIG.
The heat-fusible resin films on the innermost side of the sheet on the three sides P1, P2, and P3 at the periphery are sealed by heat welding. The most common method of joining the peripheral portions P1, P2, and P3 is heat joining between resin films by applying heat and pressure. However, in order to improve the long-term reliability of the sealed portion, the metal foil, which is one component of the laminate sheet 10, is used. It is desirable to join them directly. In this case, the heat-fusible resin film on the innermost side of the sheet needs to be partially removed in order to butt the metal foils at the periphery of the sheet. It is preferably used.

The dish-shaped container portion 6 is provided with an electrode accommodating recess 11 for accommodating the laminated electrode 4 therein. The electrode accommodating recess 11 has a rectangular shape whose external shape is slightly larger than the outer dimensions of the rectangular laminated electrode 4. The radius of curvature R1 of the opening corner and the radius of curvature R2 of the bottom corner are the same as that of the laminated electrode 4. 5 to 0.5 mm, respectively, in consideration of the ease of insertion into the concave portion and the moldability of the concave portion.
It is provided within a range of 0.3 mm. The depth D of the housing recess 11 is 10 to 2 depending on the thickness of the laminated electrode 4.
mm.

The angle θ of the opening set between the side wall of the electrode receiving recess 11 and the flat upper surface shown in FIG. 6 also depends on the moldability of the recess and the ease of inserting the laminated electrode 4 into the recess 11. 8
0-90 ° is preferred.

Considering the ease of inserting the laminated electrode 4 into the concave portion 11, the four sides of the rectangle are not made to have the same angle, but one side of the open side shown in FIG. If the inclined surface is inclined at an angle of about 45 ° and the insertion guide portion of the laminated electrode is provided, the insertion of the laminated electrode into the concave portion 11 can be facilitated. In this case, the curvature radius R3 of the inclined corner where the inclined surface and the bottom surface of the concave portion intersect is 1.5 to 0.3.
mm, the radius of curvature of the opening corner set between the inclined surface and the upper surface flat portion is the same as or slightly larger than R1, so that the electrode is easily slid into the inclined surface, and the insertion guide into the concave portion is facilitated. preferable.

The laminated electrode 4 having a thickness of about 3 to 4 mm
When the separator 3 made of a polymer sheet holding a non-aqueous electrolyte is slightly larger in dimensions than the positive electrode plate 1 and the negative electrode plate 2, the protruding separator 3 has elasticity. The radius of curvature R1 of the opening corner of the housing recess 11 is 1-2 mm, and the radius of curvature R2 of the bottom corner of the electrode housing recess 11 shown in FIG. 6 is 0.4-0.6 m.
When m, it is easy to position the corner of the separator at the opening of the concave portion, and the useless space between the concave portion after accommodating the electrode and the periphery of the laminated electrode 4 can be further reduced.

Laminated sheet 10 mainly composed of resin film
Uses a PET film and / or a nylon film as a heat-resistant first resin film, and a polyethylene film and / or a polypropylene film as a heat-fusible second resin film, while using an aluminum foil as a metal foil. And a total thickness of 80 to 180
They were joined together at μm. Then, one of the two rectangular laminated sheets, which is folded at the center in the longitudinal direction, is subjected to deep drawing to thereby form the electrode housing recess 11.
Was molded.

1, 2 and 4, reference numeral 12 denotes a polypropylene or polyethylene insulating film coated so as to surround the leads 8 and 9, respectively. Side P2 of the seal part
When the lead is pulled out to the outside, electrical insulation is provided between the lead and the aluminum foil in the laminate sheet.

A predetermined amount of a non-aqueous electrolyte in which lithium hexafluorophosphate is dissolved in a mixed solvent of ethylene carbonate and ethyl methyl carbonate is injected into the outer case 7 before sealing the periphery thereof. Of the electrode and the separator.

[0027]

Next, specific examples of the flat battery according to the present invention will be described.

One end of each of the leads 8, 9 whose center is covered with an insulating film 12 made of a polypropylene film,
It is welded to the lead connection part of the positive electrode plate and the negative electrode plate, respectively. A separator made of a polymer sheet is arranged between the positive electrode plate and the negative electrode plate, and the whole is laminated and integrated to form a total thickness of 4.
mm, and the size of the laminated electrode 4 is about 38 × 60 mm.
The laminated electrode 4 is accommodated in a rectangular electrode accommodating recess 11 provided on a laminated sheet 10 in which a modified nylon film, an aluminum foil, and a polypropylene film are integrated. At this time, the electrode accommodating recess 11 is provided in accordance with the external shape of the laminated electrode 4. The radius of curvature R1 of the opening corner is 1.5 mm, and the radius R2 of the bottom corner is 0.5.
mm, the inclination angle θ is set at 85 °, and the depth D is set at slightly less than 4 mm, so that the electrode 4 can be easily accommodated so that a useless space hardly occurs between the two.

Next, the left flat plate portion 5 of the laminate sheet 10 is folded rightward at a folding line T at the center of the sheet, and is superposed on the dish-shaped container portion 6. Then, both sides P1, P3 of both parts 5, 6 are sealed by heat welding. Then, from the open side P2, the electrode accommodating recess 11
A predetermined amount of electrolyte is injected into the inside, and one side P2 is sealed by heat welding. At this time, the insulating film 12 covering a part of the leads 8 and 9 is also made of the same material as the innermost polypropylene film of the laminate sheet 10, so that the films are well welded to each other and the positive and negative leads 8 and 9 are formed. Only the leading end protrudes outside from one side P2 of the outer case 7.

In the present invention, in addition to the embodiments described above, the outer case can be constructed in various modes. For example, in the above example, the flat plate portion 5 and the dish-shaped container portion 6 are provided continuously on one laminated sheet 10, and the three peripheral sides which are folded at the center in the length direction and overlapped are sealed. However, the outer case 7 may be formed by forming the flat plate portion 5 and the dish-shaped container portion 6 separately and sealing all four sides around the overlapping portion.

Further, as described above, if an inclined surface is provided on one side of the electrode accommodating concave portion and this is used as a guide for inserting the laminated electrode into the concave portion, the electrode can be smoothly accommodated in the concave portion, thereby assembling the battery. Productivity can be increased.

[0032]

According to the present invention, a flat laminated electrode can be accommodated in the electrode accommodating recess of the outer case mainly composed of a resin film without creating a useless space, and the external dimensions of the battery can be reduced in size. be able to. Furthermore, the work of accommodating the stacked electrodes in the electrode accommodating recesses can be performed smoothly and easily, and the production efficiency of the battery can be improved.

[Brief description of the drawings]

FIG. 1 is a front view showing a battery according to an embodiment of the present invention.

FIG. 2 is a top view of the battery.

FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 2;

FIG. 4 is an enlarged vertical sectional view taken along the line IV-IV in FIG. 2;

FIG. 5 is a plan view of a laminate sheet constituting the outer case.

FIG. 6 is a longitudinal sectional view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Separator 4 Laminated electrode 5 Flat plate part 6 Dish-like container part 7 Outer case 8 Lead 9 Lead 10 One laminated sheet 11 Electrode accommodation recess

Continued on the front page (72) Inventor Masahiko Ogawa 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 5H011 AA09 CC02 CC06 CC10 DD05 DD06 DD13 GG01 HH02 JJ12 KK00 KK01 KK03 5H029 AJ14 AK03 AL07 AM00 AM16 BJ04 CJ03 CJ05 DJ02 DJ03 EJ01 EJ12 HJ00 HJ04

Claims (5)

[Claims] 1. A laminated electrode in which a film-shaped or sheet-shaped positive electrode plate, a separator and a negative electrode plate are laminated and integrated, and a pair of laminated sheets mainly composed of a resin film. And an outer case sealed around the overlapped sheet. One of the pair of laminated sheets is a flat plate-like portion, and the other is a dish-like container portion having an electrode receiving recess for receiving the laminated electrode. A flat battery, wherein the periphery of a sheet is sealed by heat welding. 2. A flat laminated electrode in which a positive electrode plate, a separator and a negative electrode plate each in the form of a film or sheet are laminated and integrated, and a single laminated sheet mainly composed of a resin film which is folded in two in a longitudinal direction central portion. And an outer case that accommodates the laminated electrode inside and heat-welds the periphery of the overlapped sheets, wherein one of the two folded laminate sheets is a flat plate-shaped part,
The other is a shallow dish-shaped container portion having a rectangular electrode housing recess in which the laminated electrode is housed, and the radius of curvature R1 of the opening corner of the rectangular electrode housing recess is 5 mm ≧ R1 ≧ 0.5 m
m, the depth D of the recess is 10 mm ≧ D ≧ 2 mm, and the radius of curvature R2 of the bottom corner formed by the side wall and the bottom wall of the recess is 1
A flat battery in which mm ≧ R2 ≧ 0.3 mm. 3. A laminated sheet mainly composed of a resin film, in which at least three layers of films are integrated, a metal foil is arranged between the first resin film and the second resin film, and The flat battery according to claim 1, wherein the resin film is made of a resin having excellent heat welding properties. 4. A flat laminated electrode in which a film-shaped or sheet-shaped positive electrode plate, a separator and a negative electrode plate are laminated and integrated, respectively, and a three-layer structure mainly composed of one resin film which is folded in two in a longitudinal center portion. It is composed of a laminated sheet integrating the above, and comprises an outer case that accommodates the laminated electrodes therein and is hermetically sealed. One of the folded laminated sheets is a flat plate-shaped part,
The other is a dish-shaped container portion having a rectangular electrode housing recess for housing the stacked electrode, one side of the electrode housing recess on the open side is an inclined surface, and the radius of curvature R1 of the opening corner of the recess is 5 mm ≧ R1 ≧ 0.5 mm, the depth D of the concave portion is 10 mm ≧ D ≧ 2 mm, and the radius of curvature R2 of the bottom corner where the side wall and the bottom wall of the concave portion intersect is 1 mm ≧ R2 ≧ 0.3 m.
m, a flat battery in which the radius of curvature R3 of the inclined corner where the inclined surface and the bottom wall intersect is 1.5 mm ≧ R3 ≧ 0.3 mm. 5. The flat battery according to claim 4, wherein the inclination angle between the inclined surface of the electrode housing recess and the bottom surface of the recess is 30 to 60 °.