JP4413338B2 - Battery bag - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery bag body (hereinafter abbreviated as a bag body) used for a battery container.
[0002]
[Prior art]
In recent years, a bag body is being used instead of a conventional casing as a battery container in response to a demand for a reduction in size and weight of a battery. In addition, an aluminum laminate film (hereinafter abbreviated as a film) that is excellent in waterproofness, light shielding property, and the like is used as the material of the bag.
[0003]
An example of a conventional bag and battery manufacturing process is shown in FIG. When manufacturing the bag body, as shown in (1) in the figure, the film 1 having a rectangular shape is folded in half at the center in the longitudinal direction to form a fold line 1a, and then shown in (2) in the figure. Then, the opposing films 1 are sealed at the side edge portions located on both ends of the polygonal line 1 a to form the seal portion 2. As a result, a bag 3 having a space S surrounded by the folded film 1 and the seal portion 2 is obtained. The reason for making the bag 3 in this way is that the device for enclosing the contents (described later) is simplified compared to the three-sided bag in which seal portions are formed at the bottom and both ends of the bag, and the bag This is because the size of 3 can be small.
[0004]
When the battery is manufactured, contents (not shown) such as electrodes are put into the obtained bag 3, and the open end of the bag 3 is closed with a heat seal or the like as indicated by reference numeral 4. . As a result, as shown in (3) in the figure, the battery 5 in which the contents are enclosed in the bag 3 is obtained. Reference numeral 6 denotes a terminal protruding outward from the opening end of the bag body 3. For the purpose of reducing the size, the battery 5 is used by folding the side edge portion of the bag body 3 located inside the seal portion 2 inward as shown in (4) in the figure.
[0005]
[Problems to be solved by the invention]
By the way, in the case of a battery, there is a battery (such as a lithium ion battery, a lithium polymer battery, or an electric double layer capacitor in which an organic electrolyte is used as an electrolytic solution) that extremely dislikes the penetration of moisture into the bag 3. Therefore, in the case of the bag 3 used for the battery container, the aluminum foil laminated in the film 1 has a thickness of about 20 μm, which is thicker than the normal bag having a thickness of about 6 to 12 μm. Is used. As a result, as shown in (4), when both end portions of the bag body 3 are folded inside the seal portion 2, it is formed at the intersection of the fold line 1a and the ridge piece portion C formed by folding. There is a possibility that pinholes and cracks will occur in the bent aluminum foil at the corners (indicated by arrows A in the figure), and moisture, light, etc. may enter the bag 3 from the corners A. It was. In addition, when the seal portion 2 is formed, it is sufficiently heated and pressurized, but it is still difficult to reliably crush the broken line 1a, and as a result, the broken line 1a itself becomes a pinhole for conducting the inside and outside of the bag body 3. There was also a possibility. The present invention has been made in view of the above circumstances, and an object thereof is to prevent the occurrence of pinholes and cracks associated with the formation of the corners in the aluminum foil.
[0006]
[Means for Solving the Problems]
The present invention is formed by sealing the opposing surfaces of a film folded in two at a polygonal line with side edges located at both ends of the polygonal line, and further folding the side edge located inside the seal. It is a battery bag body, and the second seal part for sealing the opposing surfaces of the film is formed at the intersection of the fold line and the ridge line formed by folding of the film. It is a feature.
[0007]
In this case, the second seal portion may be formed over the entire broken line.
[0008]
In addition, the second seal portion may be formed obliquely at corners of the fold line and the seal portion at the side edge on each of both end sides of the fold line.
The bottom surface of the bag formed by the second seal portion may be semicircular .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, parts having the same configurations as those of the conventional bag 3 or battery 5 are given the same reference numerals, and the description thereof is omitted.
[0010]
An example of the manufacturing process of the bag which concerns on this invention, and the battery using this bag is shown in FIG. In manufacturing the bag body, first, like the conventional bag body 3, as shown in (1) in the figure, the rectangular film 1 is folded in half at the center in the longitudinal direction, and then in the figure ( As shown in 2), the opposing films 1 are sealed at the side edge portions located on both ends of the polygonal line 1 a to form the seal portion 2. As a result, a bag similar to the conventional bag 3 is created.
[0011]
Furthermore, in the bag according to the present invention, the opposing films 1 are sealed along the fold line 1a with a predetermined width W from the fold line 1a, and the second seal portion is formed over the entire area of the fold line 1a at the bottom of the bag body. 7 is formed. As a result, as shown in (3) in the figure, a bag body 31 having a space S ′ surrounded by the seal portion 2 and the second seal portion 7 is obtained.
[0012]
In manufacturing the battery, after the contents (not shown) such as electrodes are put into the obtained bag 31, the open end of the bag 31 is denoted by reference numeral 4 as in the conventional bag 3. Close with a heat seal or the like. As a result, as shown in (4) in the figure, a battery 51 in which the contents are enclosed in the bag 31 is obtained. Similar to the conventional battery 5, the battery 51 is used by folding the side edge portion located inside the seal portion 2 inward as shown in FIG.
[0013]
In the case of the bag body 31 according to the present invention, since the second seal portion 7 is formed at the bottom of the bag body 31, the broken line 1 a is in a state where two films 1 are laminated. Therefore, the mechanical strength of the broken line 1a is improved by the amount of the laminated film 1 as compared with the conventional bag 3. Moreover, the bending diameter when the broken line 1 a is bent increases by the thickness increase due to the lamination of the film 1. As a result, as shown in the above (5), even when both end portions of the bag body 31 are folded inside the seal portion 2, at the corner portion A formed at the intersection of the ridge line C and the broken line 1a, Pinholes and cracks do not occur in the aluminum foil laminated in the folded film 1. Even if a pinhole or crack occurs in the broken line 1a (especially the corner A), the communication between the inside of the bag body 31 and the pinhole or crack isolates the broken line 1a from the inside of the bag body 31. This is prevented by the presence of the second seal portion 7 that does not affect the inside of the bag body 31. That is, according to the present invention, the occurrence of pinholes and cracks at the corners A, and the intrusion of moisture and light from the corners A into the bag 3 due to the pinholes are prevented.
[0014]
However, in order to secure the volume of the space S ′, it is desirable to make the width W of the second seal portion 7 as small as possible. Incidentally, in the case of a bag body in which a liquid is sealed, generally, the seal portion needs to have a width of about 3 mm, but the second seal portion 7 in the present invention aims at sealing the bag body 31. However, the width is 1 mm or less because the purpose is to prevent the occurrence of defects at the intersection of the ridge line C and the broken line 1a. Also in this bag body 31, as in the case of the conventional bag body 3, since the bottom portion of the bag body 31 is formed by the broken line 1 a, the second seal portion 7 formed at the bottom portion of the bag body 31 is sufficient. Even if the adhesive strength is not high, liquid leakage or the like does not occur from the bottom of the bag 3.
[0015]
In addition, in the said embodiment, although the 2nd seal | sticker part 7 was formed over the whole region of the broken line 1a, the 2nd seal part 7 is formed in the cross | intersection part of the folded line 1a and the folding location of the bag body 31 at least. If so, the effect is demonstrated.
[0016]
2 to 4 show such an example. In these examples, the second seal portion 7 is formed only at both end portions of the broken line 1a, and the folded portion 1a and the folded portion of the bag body 31 (the portion indicated by the dotted line F in the figure) are formed by these second seal portions 7. The crossing part (part shown by the arrow B in the figure) is sealed. In the example of FIG. 2, when the second seal portion 7 is formed so as to obliquely cross both ends of the broken line 1 a, the example of FIG. 3, the second seal portion 7 is replaced by the second seal portion 7. This is an example in which the bottom surface of the formed bag body 31 is formed so as to form a semicircular shape. The example of FIG. 4 is an example in which the second seal portion 7 is formed only at the intersection B between the folding line 1 a and the folded portion of the bag body 31 so as not to overlap the seal portion 2. By forming the second seal portion 7 in this way, a bag body 31 having the same size as that of the conventional bag body 5 and hardly causing defects such as pinholes can be obtained.
[0017]
Further, for example, as shown in FIGS. 2 and 3, the bottom surface of the bag body 31 formed by the second seal portion 7 and the bottom surface of the electrode sealed in the bag body 31 are made substantially the same shape. The dead space between the bottom surface of the bag 31 and the bottom surface of the electrode can be reduced, and the effect that the space S ′ can be used effectively is obtained. In the case of FIG. 2, both end portions of the bottom surface are diagonally cut out on the bottom surface of the electrode 8 in accordance with the bottom surface shape of the bag body 31 formed by the second seal portion 7 that obliquely crosses both end portions of the broken line 1 a. A notch 8a is formed. In the case of FIG. 3, the bottom surface of the electrode 8 is also formed in a semicircular shape according to the bottom surface of the semicircular bag body 31 formed by the second seal portion 7. Of course, as shown in FIG. 4, the shape of the bottom surface of the bag 31 and the bottom surface of the electrode 8 do not have to be matched.
[0018]
In addition, the shape of the bag body 31 according to the present invention and the sealing range by the second seal portion 7 or the shape of the bottom surface of the bag body 31 are not necessarily limited to the above embodiments, and depart from the spirit of the present invention. It goes without saying that various modifications are possible without departing from the scope.
[0019]
【The invention's effect】
As described above, in the case of the bag according to the present invention, the formation of the second seal portion improves the mechanical strength of the bottom of the bag. As a result, it is possible to prevent pinholes and cracks in the aluminum foil laminated in the film constituting the bottom, and the intrusion of moisture and light into the bag due to the folding of the bottom. Is done.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a manufacturing process of a bag and a battery according to the present invention.
FIG. 2 is a diagram showing an example of the shape of a bag according to the present invention.
FIG. 3 is a diagram showing an example of the shape of a bag according to the present invention.
FIG. 4 is a diagram showing an example of the shape of a bag according to the present invention.
FIG. 5 is a diagram showing an example of a conventional bag body and battery manufacturing process.
[Explanation of symbols]
1 Film (aluminum laminate film)
1a Polygonal line 2 Seal part 7 Second seal part 8 Electrode 31 Bag (Battery bag)
51 battery

Claims (4)

  A battery bag formed by sealing the opposing surfaces of a film folded in two at a polygonal line with side edges located on both ends of the polygonal line, and further folding the side edge located inside the seal. The battery is characterized in that a second seal portion for sealing the opposing surfaces of the film is formed at the intersection of the fold line and the ridge line formed by folding of the film. Bag body.   The battery bag according to claim 1, wherein the second seal portion is formed over the entire area of the broken line. 2. The battery according to claim 1 , wherein the second seal portion is formed obliquely at corners of the broken line and the seal portion of the side edge portion at each of both end sides of the broken line. Bag body. 2. The battery bag according to claim 1 , wherein a bottom surface of the bag formed by the second seal portion has a semicircular shape .

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