JP2005228573A - Closed type battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a closed type battery in which protrusion of an insulating resin film at heat welding is suppressed, in which change in a protrusion amount of the insulating resin film before and after welding is small, and in which aggravation of capacity efficiency can be evaded by stabilizing the outer dimension of the battery. <P>SOLUTION: In the closed type battery which is provided with a sheath material 4 composed of a metal laminate resin film to mold a battery housing part 6, and a power generating element 1 housed in the battery housing part 6 of this sheath material 4, and which has such a structure that terminals 2, 3 of which the one end is connected to the power generating element 1 are heat welded to the sheath material 4 via the insulating resin film 5 and taken out into the outside of the sheath material 4 as the outer terminals 2, 3, notches 7, 7 are formed at the end part of the sheath material 4 facing the heat welding part of the outer terminals 2, 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sealed battery using a metal laminate resin film as an exterior material, and more particularly to a sealed battery capable of avoiding deterioration in volumetric efficiency by stabilizing the outer dimensions of the battery.

  In recent years, there have been remarkable developments in technologies aimed at rapid performance enhancement, weight reduction, and miniaturization in portable electronic devices such as video cameras and headphone stereos, and a drive power source for operating these electronic devices for a long time. Technical requirements for higher energy and higher capacity of the secondary battery are also increasing.

  In order to meet these technical demands, the development of non-aqueous electrolyte secondary batteries using materials that can occlude and release lithium, such as lithium metal, lithium alloys, or carbonaceous materials, is actively promoted. It became so. Among these non-aqueous electrolyte secondary batteries, from the technical point of view that reducing the volume occupied by elements other than the power generation element of the battery is advantageous for increasing the energy and size of the battery, it has been conventionally used as a battery exterior material. Instead of the metal cans made of iron or aluminum, a sealed battery using a metal laminate resin film that can be made thinner as an exterior material has been attracting attention.

  The metal laminate resin film is formed by laminating and laminating a soft metal film such as an aluminum foil capable of preventing permeation of electrolyte solution, moisture and gas, and a plastic film such as nylon, polyethylene, and polypropylene. . When this metal laminate resin film is used as a battery exterior material, the periphery of the exterior material is sealed by thermal fusion in a state where the power generation element is accommodated. And since increasing the proportion of the power generation element in the battery directly increases the capacity of the battery, the exterior material is subjected to rectangular drawing and the power generation element is tightly stored in the drawing part. By doing so, the unnecessary space part which is not concerned with battery capacity other than an electric power generation element is made small as much as possible.

  In addition, in a battery using such a metal laminate resin film as an exterior material, the lead wires (positive and negative electrode terminal plates) connected to the positive and negative electrodes of the power generation element to be housed are also heat-sealed with the outer periphery of the exterior material and externally provided. Generally, a structure that is taken out of the battery as a terminal is adopted. That is, the external terminal and the metal laminate resin film as the exterior material are heat-sealed through an insulating resin film made of polyethylene, polypropylene, or the like to the heat fusion portion of the external terminal, and the external terminal and the metal laminate resin film The electrical insulation with the soft metal film that constitutes is strengthened.

  That is, in a conventional sealed battery using the above metal laminate resin film as an exterior material, the power generation element 1 from which the negative electrode (positive electrode) terminal 2 (3) as shown in FIG. The negative electrode (positive electrode) terminal 2 (3) housed in the draw forming part 6 of the exterior material 4 and led out of the battery is heat-sealed through the peripheral portion of the exterior material 4 and the insulating resin film 5. Is done.

  The power generating element 1 includes a negative electrode plate that holds a negative electrode material on a negative electrode current collector that is a support thereof, and a positive electrode plate that holds a positive electrode active material on a positive electrode current collector that is a support. Further, it is formed by being wound into a long cylindrical shape with a sheet-shaped or foil-shaped separator interposed between the positive and negative electrodes while holding the electrolytic solution.

  Further, the power generating element 1 is electrically connected to the negative electrode thereof, and is electrically connected to the positive electrode and the negative electrode terminal 2 having a portion where the insulating resin film 5 made of polypropylene is fused, and similarly, the insulating resin film. A positive electrode terminal 3 having a portion where 5 is fused is provided, and both the positive and negative electrode terminals 2 and 3 extend from the power generating element 1 along a direction parallel to the winding axis.

On the other hand, in order to prevent a short circuit between the external terminal of the conventional nonaqueous electrolyte secondary battery encapsulating the power generation element with the exterior material and the metal exposed portion of the end face of the exterior material, the power generation element is encapsulated with the exterior material, There has also been proposed a sealing structure in which an insulating resin film protrudes outward from the end face of the exterior material and is fused when the edges of the exterior material are overlapped and joined by heating and pressurizing (for example, Patent Documents). 1).
Japanese Patent Laid-Open No. 11-40114 (page 1-5, FIGS. 1 to 5)

  In the sealed battery having a conventional structure in which the insulating resin film is protruded outward from the end face of the exterior material and fused to prevent a short circuit between the external terminal and the exposed metal portion of the end face of the exterior material. From the technical point of view of reducing the external dimensions of the insulating resin film, it is desirable to make the protruding portion of the insulating resin film from the exterior material as small as possible, but in order to more reliably prevent short circuit in the heat-sealed portion, A certain amount of protrusion is required, and it is not preferable that this protrusion is excessive or small.

  However, the protruding amount of the insulating resin film varies greatly depending on the processing conditions when the insulating resin film sandwiching the terminals and the exterior material are heat-sealed, and there is a problem that it is difficult to obtain a stable dimension. That is, the protruding amount of the insulating resin film is likely to vary greatly depending on the processing conditions such as the shape, temperature, pressing force, pressing time, etc. of the metallic tool (pressing jig) that presses the heat fusion part. In order to control strictly, there was a difficulty that required a lot of labor.

  Further, a battery built in an electronic device or the like is required to suppress variations in external dimensions as much as possible in order to realize a close layout with peripheral components. Therefore, also from this viewpoint, it is desirable to suppress variation in the protruding amount of the insulating resin film to be small and stabilize the protruding amount of the insulating resin film. However, the actual situation is that the insulating resin film is not stable because the fusion part is crushed at the time of heat-sealing in the sealing process, and the protruding part is pushed out in the extending direction of the terminal, so that the protruding amount changes. There is a need for a countermeasure to stabilize the amount of protrusion within a certain range.

  The present invention solves the above-described conventional problems, suppresses the protrusion of the insulating resin film at the time of heat-sealing, reduces the change in the protruding amount of the insulating resin film before and after the fusion, and stabilizes the outer dimensions of the battery. It is an object of the present invention to provide a sealed battery capable of avoiding deterioration in volumetric efficiency.

  In order to achieve the above object, the inventors of the present application suppress the protrusion of the insulating resin film at the time of heat fusion, and reduce the change and variation in the protrusion amount of the insulating resin film before and after the fusion. The structure was studied earnestly.

  As a result, the end of the exterior material to which the external terminal is fused via the insulating resin film is cut into a concave shape in advance to form a notch, and the three sides around the exterior material including the cut portion (notch) are removed. To stably manufacture a battery in which the protrusion of the insulating resin film during heat fusion is effectively suppressed when the insulating resin film is heat-sealed, and the change in the amount of protrusion of the insulating resin film before and after the fusion is small. For the first time. The present invention has been completed based on the above findings.

  That is, a sealed battery according to the present invention includes an exterior material made of a metal laminate resin film formed with a battery housing portion, and a power generation element housed in the battery housing portion of the exterior material, and one end of the power generation element is disposed on the power generation element. In a sealed battery having a structure in which a connected terminal is thermally fused with an exterior material via an insulating resin film and is taken out of the exterior material as an external terminal, the exterior material end facing the thermal fusion part of the external terminal A notch is formed in the part.

  According to the sealed battery of the present invention having the above-described configuration, since the notch is formed in the end portion of the exterior material facing the heat-sealed portion of the external terminal, the insulating resin film softened during the heat-sealing is crushed and extruded. Even if it is done, it is extruded and accommodated in the notch, and it is not extruded to the exterior direction of the exterior material. Therefore, a battery with a small change in the protruding amount of the insulating resin film can be obtained, and as a result, the protruding amount of the insulating resin film can be suppressed to a small value, and the protruding amount can be stabilized. A battery with high efficiency is obtained. In addition, since a short circuit between the external terminal and the exterior material can be reliably prevented, a battery with high safety can be obtained.

  Further, in the sealed battery, in the portion where the exterior material and the external terminal are heat-sealed through the insulating resin film, the protruding amount from the end surface of the exterior material of the heat-insulated insulating resin film is 0.2 mm. The following is preferable.

  As described above, by making the amount of protrusion of the heat-insulated insulating resin film from the end face of the exterior material 0.2 mm or less, a battery with less wasted portions and high capacity efficiency can be obtained, and the insulating resin film As a result of this protrusion, the layout of peripheral parts is not affected, and the degree of freedom in layout design can be increased. Further, it is possible to omit a complicated operation of cutting or grinding the excessively protruding portion to adjust the dimensions.

  Furthermore, in the sealed battery, the notch is preferably formed in a rectangular shape, and the long side length of the rectangular notch is preferably larger than the width of the external terminal.

  As described above, by forming the longer side length of the rectangular cutout to be larger than the width of the external terminal, even if the insulating resin film softened at the time of heat fusion is crushed and extruded, it is sufficiently accommodated in the cutout portion. The Therefore, the insulating resin film is not extruded toward the outside of the exterior material, and the protruding amount can be further reduced.

  According to the sealed battery according to the present invention having the above-described configuration, since the cutout is formed at the end of the exterior material facing the heat-sealed portion of the external terminal, the softened insulating resin film is crushed during heat-sealing. Even if it is extruded, it is extruded and accommodated in the notch, and does not protrude outward of the exterior material. Therefore, a battery with a small change in the protruding amount of the insulating resin film can be obtained, and as a result, the protruding amount of the insulating resin film can be suppressed to a small value, and the protruding amount can be stabilized. A battery with high efficiency is obtained. In addition, since a short circuit between the external terminal and the exterior material can be reliably prevented, a battery with high safety can be obtained.

  Hereinafter, an embodiment of a sealed battery according to the present invention will be specifically described with reference to the accompanying drawings.

  FIG. 1 is an exploded perspective view showing an assembled state of a power generating element 1 and an exterior material 4 constituting a sealed battery to which the present invention is applied. The power generation element 1 includes a negative electrode plate in which a negative electrode material is held on a negative electrode current collector that is a support, a positive electrode plate in which a positive electrode active material is held on a positive electrode current collector that is a support, and the negative electrode The separator is interposed between the plate and the positive electrode plate to hold the electrolytic solution and prevent a short circuit between the two electrodes. These negative electrode plate, positive electrode plate, and separator are each formed into a thin sheet shape or foil shape, and wound into a long cylindrical shape in a laminated state. The power generating element 1 is provided with a negative electrode terminal 2 electrically connected to the negative electrode and a positive electrode terminal 3 electrically connected to the positive electrode, both in a direction parallel to the winding axis. It extends from the power generation element 1.

  Moreover, as the exterior material 4 that accommodates the power generation element 1, a metal laminate resin film 5 in which a drawn portion 6 was previously formed by drawing was used. As this metal laminate resin film, an aluminum laminate film comprising three layers of a nylon layer having a thickness of 25 μm, a soft aluminum layer having a thickness of 40 μm, and a polypropylene layer having a thickness of 30 μm is used. Drawing was performed so as to be the outermost side, and a rectangular drawn portion 6 was formed. Further, the portions where the negative electrode terminal 2 and the positive electrode terminal 3 abut on the heat-sealed portion of the exterior material 4 were notched into a concave shape to form the notched portions 7 respectively.

  Next, one side of the rectangular drawn portion 6 is valley-folded, the power generation element 1 and the electrolyte are stored in the drawn portion 6, and three sides other than the valley-folded side are made of metal. The battery was sealed by pressing with a tool and heat-sealing to prepare a sealed battery as shown in FIG.

  At this time, the negative electrode terminal 2 and the positive electrode terminal 3 are each pulled out to the outside of the exterior material 4 and serve as external terminals of the battery. An insulating resin film 5 made of polypropylene is preliminarily bonded to each of the portions where the negative electrode terminal 2 and the positive electrode terminal 3 are in contact with each other at the heat-sealed portion of the outer packaging material 4, and the negative electrode terminal 2 and the positive electrode terminal 3 are the insulating resin. The film 5 is heat-sealed in a state where the film 5 is sandwiched between the temporarily-bonded portions.

  In the present embodiment, the example in which the insulating resin film 5 is temporarily fused to the exterior material 4 is shown. However, the insulation resin film 5 is deformed by fusing the three surrounding sides including the cutout portion 7 of the exterior material 4. As long as it can be suppressed, the temporary fusion bonding of the insulating resin film 5 may be performed on the surfaces of the negative electrode terminal 2 and the positive electrode terminal 3 as external terminals.

  FIG. 6 shows a conventional structure in which the insulating resin film 5 is protruded outward from the end surface of the exterior material 4, but the positive electrode without protruding the insulating resin film 5 outward from the end surface of the exterior material 4. The battery of this embodiment may be formed by covering the insulating resin film 5 so as to cover both the terminal 3 and the negative electrode terminal 2 simultaneously. On the other hand, as shown in FIG. 2, the positive electrode terminal 3 and the negative electrode terminal 2 may be individually covered with an insulating resin film 5.

  Next, more specific examples of the sealed battery according to the present invention will be described below in comparison with a sealed battery of a comparative example having a conventional structure.

[Example]
FIG. 3 is a plan view showing a dimension example of the external terminal fusion part of the sealed battery according to the present embodiment, and FIG. 4 shows heat generated by pressing a metal tool against the fusion part of the sealed battery shown in FIG. It is a top view which shows the state which has melt | fused.

  In this embodiment, a nickel plate having a thickness of 0.1 mm and a width of 4 mm is used as the negative electrode terminal 2, while an aluminum plate having a thickness of 0.1 mm and a width of 4 mm is used as the positive electrode terminal 3. did. The distance A between the negative electrode terminal 2 and the positive electrode terminal 3 was 16 mm. The end portions of the outer packaging material 4 for fusing the negative electrode terminal 2 and the positive electrode terminal 3 are cut into concave shapes, and a notch 7 is formed. The width B of the cut portion (notch 7) is 10 mm, the cut depth C from the end of the exterior material 4 is 1 mm, and the positions of the terminals 2 and 3 after fusion are the width (10 mm) of the cut portion 7. The distance D between the concave cutouts 7 and 7 was set to 10 mm so as to be in the center.

  As shown in FIG. 3, a band-shaped insulating resin film 5 (coarse shaded portion) is temporarily fused to the terminal fused portion of the exterior material 4, and the width E of the insulating resin film 5 is 6 mm. The length F was set to 36 mm, and the exterior material end and the film end were combined and temporarily fused so as to be equal on both sides around the center X between the terminals. The fusion performed at the time of sealing was performed by pressing a metal tool (pressing jig) 8 having a pressing surface as shown by a fine hatched portion in FIG. 4 against the fused portion. Specifically, the metal tool 8 heated to a temperature of 180 ° C. is pressed for 10 seconds from both sides of the exterior material 4 with the terminals 2.3 sandwiched therebetween via the insulating resin film 5 as shown in FIG. A heat fusion treatment was performed. The metal tool 8 has a concave shape in the same manner so that the metal tool 8 is pressed against the inner portion by 0.5 mm from the end of the exterior material 4. 8 was used. As for the size of the pressing surface of the metal tool 8, the width H was 5 mm, and the width G of the concave portion where the terminals 2 and 3 were fused was 4 mm. In FIG. 4, the pressing surface of the metal tool (pressing jig) 8 indicated by the fine hatched portion is the fused portion as it is. As described above, the power generation element 1 is accommodated in the drawing portion of the exterior material 4 in which the notches 7 and 7 are formed, and the metal is formed from both sides of the exterior material 4 with the terminal 2.3 sandwiched through the insulating resin film 5. 50 cells of the sealed battery according to the example were manufactured by pressing the tool (pressing jig) 8 and carrying out the heat fusion treatment.

[Comparative example]
On the other hand, as a comparative example, a cell was prepared in which the notch portion was not formed and the size of the tab fused portion was the same as in the example. That is, as shown in FIG. 5, the insulating resin film 5 to be temporarily fused is protruded by 1 mm from the end portion of the exterior material 4 without forming a concave notch at the end portion of the terminal lead-out portion of the exterior material 4. An exterior material 4 having the same specifications as in the example was prepared except for the temporary fusion. The heat sealing was performed by pressing the metal tool 8 having a width w of 4 mm over an area range (fine hatched portion) from the end of the exterior material 4 to the inner portion by 0.5 mm. As described above, the power generation element 1 is housed in the drawing-formed portion of the exterior material 4 that does not form a notch, and both sides of the exterior material 4 sandwich the terminal 2.3 via the insulating resin film 5 protruding from the exterior material 4. Then, a metal tool (pressing jig) 8 was pressed to carry out a heat-sealing process, whereby 50 cells of a conventional sealed battery according to the comparative example were manufactured.

As described above, for each sealed battery according to the example and comparative example manufactured by 50 cells each, the amount of protrusion from the end of the exterior material (packaging material) 4 of the insulating resin film 5 was measured before and after the fusion process. The amount of protrusion deformation of the insulating resin film was calculated by calculating the difference before and after the fusion process. The results of calculating the average value, maximum value and minimum value are shown in Table 1 below.

  As is apparent from the results shown in Table 1 above, according to the sealed battery according to each example in which the notches 7 and 7 are formed at the end portions of the exterior material 4 facing the heat-sealed portions of the external terminals 2 and 3. For example, even if the insulating resin film 5 softened at the time of heat-sealing is crushed and extruded, the insulating resin film 5 is extruded and accommodated in the notches 7 and 7, and does not protrude outward of the exterior material 4. Therefore, a battery with a small change in the protruding amount of the insulating resin film 5 can be obtained, and as a result, the protruding amount of the insulating resin film 5 can be suppressed to be small and the protruding amount can be stabilized, so that there are few useless portions. A battery with high capacity efficiency was obtained. Moreover, since the short circuit with the external terminals 2 and 3 and the exterior | packing material 4 can be prevented reliably, the battery with high safety | security was obtained.

  Specifically, the protrusion deformation amount of the insulating resin film 5 in each sealed battery according to the example is 0.15 mm on the average and 0.2 mm at the maximum, whereas the conventional deformation according to the comparative example In the sealed battery having the structure, the average value of the projecting deformation amount of the insulating resin film 5 is as large as 0.52 mm, and the maximum value is 0.7 mm. In the sealed battery according to the present embodiment, the projecting of the insulating resin film 5 is performed. It has been found that the amount of deformation is effectively reduced.

  In the batteries of the examples and comparative examples, the dimensions of the external terminal part before fusion are 4 mm at the fusion part, the width of the unfused part at the end of the exterior material 4 is 0.5 mm, and the insulating resin The protruding amount of the film is 1 mm, and the total dimension from the fused part to the tip of the insulating resin film 5 is 5.5 mm. However, as is apparent from the results after the actual heat fusion treatment, the dimensions from the fusion part of the battery of the example to the end of the insulating resin film 5 are within 5.7 mm for all the batteries. On the other hand, in the battery of the comparative example, there is a battery having a thickness of 6.2 mm. Therefore, the battery according to the present embodiment can reduce a useless space portion, which is advantageous in battery design. found.

The disassembled perspective view which shows the assembly state of the electric power generation element and exterior | packing material of a sealed battery to which this invention is applied. The perspective view which shows schematic structure of the sealed battery to which this invention is applied. The top view which shows the dimension example of the external terminal melt | fusion part of the sealed battery which concerns on an Example. FIG. 4 is a plan view showing a state in which a metal tool is pressed against a fusion part of the sealed battery shown in FIG. 3 and thermally fused. The top view which shows the structure of the external terminal melt | fusion part of the conventional sealed battery which concerns on a comparative example. The perspective view which shows schematic structure of the conventional sealed battery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric power generation element 2 Negative electrode terminal 3 Positive electrode terminal 4 Exterior material (metal laminated resin film)
5 Insulating resin film 6 Drawing part 7 Notch 8 Metal tool

Claims (3)

An exterior material made of a metal laminate resin film formed with a battery housing portion and a power generation element housed in the battery housing portion of the exterior material, and a terminal having one end connected to the power generation element via an insulating resin film In a sealed battery having a structure that is heat-sealed with an exterior material and taken out of the exterior material as an external terminal, a notch is formed at an end of the exterior material facing the heat-sealed portion of the external terminal. A sealed battery. In the part where the exterior material and the external terminal are heat-sealed through the insulating resin film, the amount of protrusion from the end surface of the exterior material of the heat-insulated insulating resin film is 0.2 mm or less, The sealed battery according to claim 1. 2. The sealed battery according to claim 1, wherein the cutout is formed in a rectangular shape, and the long side length of the rectangular cutout is formed larger than the width of the external terminal.

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