JP2006040596A - Flat battery and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat battery capable of widening the inner volume of the battery and decreasing the weight while electrolyte leakage resistance similar to a battery sealed by crimping through a gasket is ensured, and to provide the manufacturing method of the flat battery. <P>SOLUTION: In the flat battery manufactured by sealing a power generation element on the inside of an outer jacket formed by fitting an inside container and an outside container with each side wall, a fitting part of the outside container and the inside container is sealed with an adhesion layer containing synthetic resin or synthetic rubber, and the side wall of the inside container has pressing force to the outer circumferential direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery that can achieve expansion and weight reduction of the internal volume and is excellent in leakage resistance.

  In recent years, with cordless and portable computers such as AV devices and personal computers, there is an increasing demand for a battery that is a power source for driving the device to be smaller, lighter, and higher in energy density. As a battery satisfying such requirements, a button (coin) type battery (hereinafter referred to as “button type battery”) is the mainstream.

A schematic cross-sectional view of these button batteries is shown in FIG. In FIG. 5, 20 is a battery, 21 is an inner container (negative electrode can), 22 is an outer container (positive electrode can), 23 is a gasket, 24 is a negative electrode, 25 is a separator, and 26 is a positive electrode. In addition, an electrolytic solution (not shown) is injected into the battery 20. As shown in FIG. 5, in the button-type battery 20, the inner container 21 and the outer container 22 that constitute the battery outer body are caulked and sealed through a gasket 23 that is a molded body, and thus airtightness is achieved. And high mechanical strength. However, in these button-type batteries, as shown in FIG. 5, the volume occupied by the fitting portion between the inner container 21 and the outer container 22 is large due to the use of the gasket 23. Since the amount of the material used for sealing is also large, the sealing portion including these (the region partitioned by the outer peripheral portion of the side wall of the outer container 22 and the inner peripheral surface of the gasket 23, that is, the two dotted lines in FIG. The area occupied by the region A ′) partitioned by is large, and there are significant restrictions on the weight reduction of the battery and the expansion of the battery internal volume. That is, in order to ensure excellent sealing performance, the width of the sealing portion (the distance between the two dotted lines in FIG. 5) needs to be approximately 1 mm or more, and the cross-sectional area of the battery in the radial direction : Ratio of the cross-sectional area of the sealing portion to S (mm ² ): T (%) is about 15% when the battery diameter is 25 mm, about 25% when the battery diameter is 15 mm, and about 64% when the battery diameter is 5 mm. The smaller the battery capacity, the greater the battery capacity loss.

  On the other hand, a battery is also proposed in which the sealing of the fitting part of the battery container is performed using an adhesive regardless of caulking using a gasket (Patent Documents 1 and 2). According to these techniques, there is a possibility that the internal volume of the battery can be increased by suppressing the volume of the portion occupied by the sealing portion.

JP 55-1111060 A Japanese Utility Model Publication No. 58-139668

  In the batteries according to Patent Documents 1 and 2, the sealing performance of the battery is mainly determined by the adhesive ability of the adhesive. However, this depends on, for example, the adhesion area, etc. When trying to reduce the thickness, the bonding area is reduced, the bonding ability is lowered, the airtightness is inferior to the battery using the gasket, and the leakage control of the electrolytic solution may be insufficient. The present invention solves such problems of the prior art, and ensures a leakage resistance equivalent to that of a battery that is caulked and sealed using a gasket, while achieving expansion and weight reduction of the battery volume. Another object is to provide a method for producing the flat battery.

  The present invention relates to a flat battery in which a power generation element is sealed inside an exterior body formed by fitting an inner container and an outer container at respective side walls, and a fitting portion between the inner container and the outer container is heated. The above-mentioned problem is solved by sealing with an adhesive layer containing a fusible synthetic resin or synthetic rubber, and imparting a pressing force in the outer peripheral direction to the side wall of the inner container.

  In the flat battery according to the present invention, the fitting portion between the inner container and the outer container constituting the battery outer body is sealed with an adhesive layer containing a synthetic resin or synthetic rubber, so that a caulking seal using a gasket is used. Thus, the ratio occupied by the sealing portion (the region partitioned by the inner peripheral wall surface of the inner container and the outer peripheral wall surface of the outer container) can be reduced, and the battery internal volume can be increased. Moreover, since the material used for the sealing can be reduced, the weight of the battery can be reduced. Furthermore, the inner container has a pressing force in the outer peripheral direction [repulsive stress toward the outer container (stress to open toward the outer container)], so that the inner container and the outer container are fitted. It is also possible to improve the airtightness, that is, the leakage resistance, by increasing the adhesion of the joint.

  From the viewpoint of enhancing the adhesiveness and insulation between the inner container and the outer container, the adhesive layer preferably has a thickness of 30 to 200 μm. Examples of the adhesive layer include those containing polyolefin as a synthetic resin, and those containing styrene-butadiene rubber as a synthetic rubber.

  Further, the flat battery manufacturing method of the present invention includes a flat battery in which a power generation element is sealed inside an outer package formed by fitting an inner container and an outer container with respective side walls (that is, the flat battery of the present invention described above). In manufacturing the battery, a cup-shaped container whose side wall is narrowed from the opening side to the bottom side as the inner container and the outer container, the inner container loaded with the power generation element, The outer container is fitted with an adhesive layer containing a synthetic resin or synthetic rubber, and the side wall of the inner container and the side wall of the outer container are connected to the bottom surface of the inner container and the bottom surface of the outer container. It compresses so that it may become substantially perpendicular | vertical.

  That is, a cup-shaped container whose side wall is narrowed from the opening side to the bottom side is used as the inner container, and the side wall is made to be substantially perpendicular to the bottom surface when fitted to the outer container. By compressing the inner container, it is possible to increase the adhesion between the inner container and the outer container by giving a pressing force in the outer peripheral direction to the side wall of the inner container. Further, by using a cup-shaped container whose side wall is narrowed from the opening side to the bottom surface side, the workability when inserting the inner container into the outer container can also be improved. .

  The inner container is a cup-shaped container having an internal angle of 0.5 to 10 ° between the perpendicular to the bottom surface and the longest straight portion of the side wall, and the outer container is a perpendicular to the bottom surface and the longest side wall. It is preferable to use a cup-shaped container having an internal angle of 1 to 20 ° with the straight portion. Further, it is recommended that the adhesive layer is heat-sealed with the inner container and the outer container.

  The flat battery of the present invention can satisfy the demand for an improvement in battery capacity because the battery internal volume can be increased while ensuring leakage resistance comparable to that of a battery caulked and sealed using a gasket. Further, the material used for the sealing portion can be reduced, and the weight of the battery can be reduced.

  Furthermore, according to the method for manufacturing a flat battery of the present invention, the flat battery of the present invention can be manufactured with good workability.

  Hereinafter, the present invention will be described in detail. FIG. 1 is a schematic cross-sectional view showing the main part of an example of the flat battery of the present invention. 10 is a battery, 11 is an inner container, 12 is an outer container, 13 is an adhesive layer, 14 is a negative electrode, 15 is a separator, 16 is a positive electrode, and 17 is an insulator. An electrolytic solution (not shown) is injected into the battery. In FIG. 1, A is a sealing portion, which is an area partitioned by the inner peripheral surface of the side wall of the inner container 11 and the outer peripheral surface of the side wall of the outer container 12.

  The inner container and the outer container constitute a battery outer package. The material is not particularly limited, and those used in conventionally known batteries [for example, stainless steel, iron (for example, cold-rolled steel plate, preferably plated with Ni or the like on its surface), copper-stainless steel A clad material, an aluminum clad material using stainless steel as a base material, etc.] may be employed.

  In the state of the battery, the inner container and the outer container are substantially perpendicular to the bottom surface of the inner container and the bottom surface of the outer container as shown in FIG. The side wall has a cup shape that narrows from the opening side toward the bottom surface side (hereinafter sometimes referred to as “taper shape”).

  The cup-shaped container having the tapered shape as described above is used as the inner container, and when the battery is made, the side wall is made substantially perpendicular to the bottom surface so that the side wall of the inner container is widened toward the outer container side. A pressing force is generated to try to peel off. By this pressing force, the side wall of the inner container is pressed against the side wall of the outer container. Such an action (spring effect) of the side wall of the inner container improves the adhesion between the inner container and the outer container, so that the airtightness of the battery, that is, the leakage resistance can be improved.

  FIG. 2 is a schematic cross-sectional view showing the main part of another example of the flat battery of the present invention. The battery of FIG. 2 has the same configuration as the battery of FIG. 1 except that the opening side of the outer container 12 is inclined toward the inner container 11. Like the battery of FIG. 2, it is more preferable that the opening side of the outer container 12 is inclined toward the inner container 11 so that the inner container 11 is prevented from coming off because the adhesion is improved.

FIG. 3 shows a cross-sectional view of the main part of the inner container 11. In FIG. 3, θ ₁ , that is, an internal angle formed by a perpendicular to the bottom surface and the longest straight portion of the side wall (hereinafter, referred to as “taper angle”). The same applies to the outer container described later.) Is 0.5 ° or more, more preferably 1 ° or more, and preferably 10 ° or less, more preferably 5 ° or less. By controlling the taper angle of the inner container side wall in such a range, the above-described spring effect becomes more remarkable. That is, if the taper angle of the inner container side wall is too small, when the battery is used, the pressing force of the inner container side wall in the outer circumferential direction is reduced, and the spring effect of the inner container side wall, that is, between the inner container and the outer container, is reduced. The adhesion improving effect may be insufficient. Moreover, when the taper angle of the inner container side wall is too large, workability at the time of battery manufacture may be lowered, for example, workability at the time of fitting with the outer container is lowered.

Moreover, since the workability | operativity at the time of fitting an inner container in an outer container improves by using the cup-shaped container which has the above taper shapes for an outer container, the productivity of a battery can be improved. FIG. 4 shows a cross-sectional view of the main part of the outer container 12. In FIG. 4, θ ₂ , that is, the angle (taper angle) formed by the perpendicular to the bottom surface and the longest straight portion of the sidewall is 1 ° or more. It is preferably 2 ° or more and 20 ° or less, more preferably 15 ° or less. By controlling the taper angle of the outer container side wall in such a range, the workability improvement effect at the time of battery production becomes more remarkable. That is, if the taper angle of the outer container side wall is too small, the workability improvement effect during battery manufacturing may not be sufficiently ensured. Further, when forming a battery, the inner container and the outer container are fitted through an adhesive layer, and the side walls of the inner container and the outer container are substantially perpendicular to the bottom surface of the inner container and the bottom surface of the outer container. However, if the taper angle of the side wall of the outer container is too large, workability may be deteriorated because the side wall is difficult to be compressed.

The shapes of the bottom surface of the inner container and the bottom surface of the outer container include, for example, a generally known flat battery (such as a button-shaped battery) such as a substantially circular shape, a substantially elliptical shape, or a substantially rectangular shape (such as a substantially square or a substantially rectangular shape) in plan view. ) And the like, but are not limited to these shapes. The size of the inner container and the outer container is not particularly limited. For example, the inner container and the outer container can be the same size as a conventionally known flat battery, and can be made larger or smaller than a conventionally known battery. You can also. Specifically, for example, in the case of a button-type battery whose bottom surface and top surface are circular in a plan view, the diameter of the bottom surface: 5 to 30 mm, the height of the side wall (vertical height with respect to the bottom surface, h in FIG. ₁ ): 1 to 5 mm, and for the outer container, the bottom surface diameter: 5 to 30 mm, the side wall height (vertical height with respect to the bottom surface, h ₂ in FIG. 4): 1 to 5 mm. It is common.

In addition, when each bottom shape of the inner container and the outer container is a substantially rectangular battery in plan view, the four corners are generally finished in a curved shape, but in the inner container and the outer container used for the battery of the present invention, The taper angle (the above θ ₁ and the above θ ₂ ) measured at a location where the side wall is linear may be within the predetermined range.

  In the battery according to the present invention, the inner container and the outer container are bonded to each other with an adhesive layer interposed therebetween. The adhesive layer contains a known synthetic resin or synthetic rubber, and these synthetic resin and synthetic rubber act as an adhesive component. Examples of the synthetic resin include polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymer; copolymers such as nylon 6, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612, nylon 6-nylon 66 copolymer, and the like. And polyamides such as polymerized nylon. In addition, the polyolefin is a modified polyolefin having a polar group (such as a carboxyl group or a hydroxyl group) introduced for the purpose of improving adhesiveness because of its low affinity with the metal constituting the inner and outer containers. Good. In the battery of the present invention, as will be described later, the inner container and the outer container are heat-sealed by an adhesive layer, and the temperature during this heat-sealing is preferably 100 to 300 ° C. For this reason, among the above synthetic resins, those that can be heat-sealed at the above-mentioned temperatures are preferable. Specifically, for example, the melting temperature measured according to the provisions of JIS K 7121 is within the range of the above-mentioned heat-sealing temperatures. It is recommended to use the synthetic resin inside.

  Examples of the synthetic rubber contained in the adhesive layer include styrene-butadiene rubber, butyl rubber, and polyisobutylene rubber. The synthetic rubber contained in the adhesive layer is preferably vulcanized in the battery state. Vulcanization of the adhesive layer containing synthetic rubber can be performed simultaneously with heat fusion to the inner container and the outer container, for example. For example, as the adhesive layer containing styrene-butadiene rubber, a commercially available sheet (such as a sheet obtained by blending a styrene-butadiene rubber with a vulcanizing agent) can be applied.

  In addition to the above synthetic resin and synthetic rubber, the adhesive layer may contain various known additives as necessary.

  The thickness of the adhesive layer is 30 μm or more, more preferably 50 μm or more, and is desirably 200 μm or less, more preferably 100 μm or less. If the thickness of the adhesive layer is too small, the adhesiveness and insulation between the inner container and the outer container may be insufficient. On the other hand, even if the thickness of the adhesive layer is made too large, not only the adhesion and insulation between the inner container and the outer container are saturated, but the amount of materials (synthetic resin, synthetic rubber, etc.) used for adhesion increases. Therefore, it may become a factor that hinders weight reduction of the battery.

According to the present invention, when the cross-sectional area of the battery in the radial direction is S (mm ² ), the ratio of the cross-sectional area of the sealing portion to the cross-sectional area of the battery in the radial direction is approximately T (%). ,
40 / (S) ^1/2 ≤ T ≤ 200 / (S) ^1/2
A flat battery can be configured. By reducing the thickness of the outer container or the inner container or by reducing the thickness of the adhesive layer, it is possible to make the value of T below the above range, but if the thickness of the outer container or the inner container is reduced too much The strength decreases and problems such as battery deformation may occur, and if the thickness of the adhesive layer is reduced too much, problems such as short circuits may occur, so the value of T is 40 / (S). it is desirable that a ^half or more, and more preferably set to 50 / ^{(S) 1/2} or more. On the other hand, as the value of T increases, the internal volume of the battery decreases. Therefore, the value of T is desirably 200 / (S) ^1/2 or less.

  When the above preferred thickness is adopted for the adhesive layer and a general-purpose container thickness is adopted, the ratio T of the cross-sectional area of the sealing portion to the cross-sectional area S of the battery in the radial direction is approximately when the battery diameter is 25 mm. 3 to 5%, about 6 to 8% at 15 mm, and about 16 to 22% at 5 mm, and the ratio T of the cross-sectional area of the sealing portion is about 1/3 to that of a flat battery using a gasket. It can be reduced to 1/5.

  The power generation elements such as the positive electrode, the negative electrode, the separator, and the electrolyte solution according to the flat battery of the present invention are not particularly limited, and those employed in conventionally known primary batteries and secondary batteries can be applied. In the battery shown in FIG. 1, an insulating material 17 is arranged between the side wall end of the inner container (negative electrode can) 11 and the outer container (positive electrode can) 12 to insulate the inner container 11 and the outer container 12. As shown, as the insulating material, those conventionally used for primary batteries and secondary batteries can be applied. In the battery shown in FIG. 1, the negative electrode 14 is disposed on the inner container 11 side and the positive electrode 16 is disposed on the outer container 12 side. However, in the flat battery of the present invention, the positive electrode is disposed on the inner container side and the outer container side. Alternatively, a structure in which a negative electrode is disposed may be used.

  Next, the manufacturing method of the flat battery of this invention is demonstrated. First, a sheet for forming an adhesive layer (a sheet containing a synthetic resin or a sheet containing a synthetic rubber) is attached to the outer side wall of the inner container or the inner side wall of the outer container. The sheet for forming the adhesive layer can be attached using, for example, a temporary adhesive. Alternatively, a method may be employed in which a thin ring-shaped molded body including a synthetic resin or a synthetic rubber for forming the adhesive layer is produced and this is fitted to the outer side wall of the inner container. Further, it can be preliminarily heat-sealed. Further, if an adhesive layer is formed on both the outer side wall of the inner container and the inner side wall of the outer container, the adhesive force can be further enhanced.

  Next, the power generation element is loaded into the inner container, for example, in a configuration as shown in FIG. The electrolytic solution is generally introduced into the battery by placing the separator at a predetermined position when the battery is assembled and then injecting the separator onto the separator. For example, in the case of the battery shown in FIG. After the negative electrode 14 is pressure-bonded to the separator 11, the separator 15 is installed, a few drops of the electrolyte is dropped on the surface of the separator 15 on the positive electrode 16 side, and then the positive electrode 16 is installed. For example, a method of dropping a few drops of electrolyte on the surface can be employed.

  Cover the inner container with the power generation element on the outer container with insulation material at the planned contact point of the inner container end, and compress (crimp) so that the side wall of the outer container is almost perpendicular to the bottom surface of the outer container Preferably, the adhesive layer is heat-sealed to the inner container and the outer container, for example, to obtain a battery as shown in FIG. There are no particular restrictions on the method of heat fusion, but for example, heat can be partially applied for fusion, and heat transfer to the power generation element can be reduced to prevent temperature rise. Therefore, induction heating using high frequency is suitable. The temperature at the time of heat fusion is preferably 100 to 300 ° C., for example. This is because if the temperature is too low, the fusion may be insufficient, and if it is too high, the power generation element may be adversely affected. Further, at the time of heat fusion, it is desirable to simultaneously cool the parts other than the part to be heated, thereby further suppressing the temperature rise of the power generation element. In addition, as described above, in the case of an adhesive layer containing a synthetic rubber, it is recommended to vulcanize the synthetic rubber simultaneously with heat fusion.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples are not intended to limit the present invention, and all modifications made without departing from the spirit of the preceding and following descriptions are included in the technical scope of the present invention.

Example Using the inner container 11 shown in FIG. 3 and the outer container 12 shown in FIG. 4, a flat battery having the structure shown in FIG. 1 was produced. The inner container 11 is made of stainless steel having a thickness of 0.2 mm, has a circular bottom surface, a diameter of 19.3 mm at the bottom surface, a diameter of 19.4 mm at the open end, and a height h ₁ shown in FIG. 9 mm, and the taper angle theta ₁ 1.5 °, the outer container 12, the thickness was made 0.2mm stainless steel, and a bottom circular, 19.9 mm diameter of the bottom surface, the diameter of the open end 20. The height h ₂ shown in FIG. 4 was 1.9 mm, and the taper angle θ ₂ was 4.5 °.

After affixing a polypropylene film for forming the adhesive layer 13 (thickness: 80 μm) to the entire outer periphery of the side wall (the straight portion shown in FIG. 3) of the inner container 11, the negative electrode 14 and the separator are attached to the inner container 11. 15, electrolyte solution and positive electrode 16 were charged and injected in this order. The negative electrode 14 was metallic lithium and had a thickness of 0.5 mm. The separator 15 was a polypropylene nonwoven fabric having a thickness of 0.32 mm. In addition, in the electrolytic solution, a mixed solvent of propylene carbonate (PC) / 1,2-dimethoxyethane (DME) = 1/1 (volume ratio), and lithium perchlorate (LiClO ₄ ) as a solute is 0.5 M. What was dissolved in the concentration was used. The positive electrode 16 is mixed with active material: manganese dioxide, conductive auxiliary agent: carbon black, binder: polytetrafluoroethylene at 94/5/1 (mass ratio) to form a positive electrode mixture, which is press-molded. The molded body (thickness: 1.4 mm) obtained in this way was used.

The inner container 11 loaded with the power generation element is covered with the outer container 12 in which an insulating material 17 is installed at a position where the end of the inner container 11 abuts, and the side wall of the outer container 12 is substantially perpendicular to the bottom surface of the outer container 12. The adhesive layer 13 is pressed against the inner surface of the side wall of the outer container 12 and then the adhesive layer 13 is thermally fused to the inner container 11 and the outer container 12 by induction heating using high frequency to obtain a battery. It was. In the heat fusion by induction heating, the conditions are a frequency of 20 kHz, a set temperature of 180 ° C., a heating time of 15 seconds, and a copper jig having a diameter of 15 mm is applied to the outside of the bottom surface of the inner container 11 and the outer container 12 for cooling. While carrying out. The battery thus obtained is a flat battery (button battery) having an outer diameter of 20 mm and a thickness of 2.5 mm. In addition, the cross-sectional area S in the radial direction of the battery is 314 mm ² , and the ratio T of the cross-sectional area of the sealing portion is 5%.
T = 90 / (S) ^1/2
The relationship represented by

Comparative Example A button type battery (outer shape: 20 mm, thickness: 2.5 mm) having a conventional configuration shown in FIG. 5 was produced. The materials for the inner and outer containers and the power generation elements are the same as in the examples, and the inner and outer containers are sealed by using injection molded gaskets (made of polypropylene) as shown in FIG. It went by. In addition, the cross-sectional area S in the radial direction of the battery is 314 mm ² , and the ratio T of the cross-sectional area of the sealing portion is 19%.
T = 340 / (S) ^1/2
The relationship represented by

  For the batteries of Examples and Comparative Examples obtained as described above, the respective battery internal volumes were compared, and the average value and standard deviation of the battery mass were compared for each of these 50 batteries. For each of the 50 batteries, the leakage state after storage for 80 days in an environment of 60 ° C. and 90% relative humidity was confirmed. The results are shown in Table 1.

  In addition, the battery internal volume ratio in Table 1 is shown as a ratio when the internal volume of the battery of the comparative example is 1.

  As can be seen from Table 1, the battery of the comparative example (the battery according to the conventional caulking seal) has high airtightness and excellent leakage resistance, but the battery of the example also has adhesion by the adhesive layer. By providing the inner container with a repulsive stress toward the outer container, a high degree of airtightness can be secured, and its liquid leakage resistance is comparable to that of the battery of the comparative example. Further, the battery of the example can secure 1.2 times the internal volume of the battery of the comparative example, and can cope with the increase in capacity of the battery. Moreover, since the material used for sealing can be reduced compared with the battery of the comparative example, the weight reduction of the battery can also be achieved.

It is a cross-sectional schematic diagram which shows the principal part of an example of the flat battery of this invention. It is a cross-sectional schematic diagram which shows the principal part of the other example of the flat battery of this invention. It is sectional drawing of the principal part of the inner side container for comprising the flat battery of this invention. It is sectional drawing of the principal part of the outer side container for comprising the flat battery of this invention. It is the cross-sectional schematic which shows the principal part of the conventional flat battery.

Explanation of symbols

10, 20 Flat battery 11, 21 Inner container 12, 22 Outer container 13 Adhesive layer 14, 24 Negative electrode 15, 25 Separator 16, 26 Positive electrode 23 Gasket A A ′ Sealing part

Claims (12)

A flat battery in which a power generation element is enclosed inside an outer package formed by fitting an inner container and an outer container at respective side walls,
The fitting part between the outer container and the inner container is sealed with an adhesive layer containing a heat-sealable synthetic resin or synthetic rubber,
A flat battery, wherein the side wall of the inner container has a pressing force in the outer peripheral direction. A flat battery in which a power generation element is enclosed inside an outer package formed by fitting an inner container and an outer container at respective side walls,
The fitting part between the outer container and the inner container is heat-sealed by an adhesive layer containing synthetic resin or synthetic rubber to form a sealing part,
The ratio of the cross-sectional area of the sealing portion to the cross-sectional area in the radial direction of the flat battery: S (mm ² ): T (%)
40 / (S) ^1/2 ≤ T ≤ 200 / (S) ^1/2
A flat battery characterized by being in the range.   The flat battery according to claim 1, wherein the adhesive layer has a thickness of 30 to 200 μm.   The flat battery according to any one of claims 1 to 3, wherein the heat-fusible synthetic resin has a melting temperature of 100 to 300 ° C.   The flat battery according to any one of claims 1 to 4, wherein the adhesive layer contains polyolefin.   The flat battery according to claim 1, wherein the adhesive layer contains styrene-butadiene rubber.   The flat battery according to any one of claims 1 to 6, wherein an opening side of the side wall of the outer container is inclined toward the inner container side. A method of manufacturing a flat battery in which a power generation element is sealed inside an outer casing formed by fitting an inner container and an outer container at respective side walls,
As the inner container and the outer container, a cup-shaped container whose side wall is narrowed from the opening side toward the bottom surface side,
The inner container loaded with the power generation element and the outer container are fitted through an adhesive layer containing a synthetic resin or synthetic rubber, and the inner container and the outer container are connected to the inner container. A flat battery manufacturing method comprising compressing the battery so as to be substantially perpendicular to the bottom surface of the outer container and the bottom surface of the outer container.   As the inner container, a cup-shaped container having an internal angle of 0.5 to 10 ° between the perpendicular to the bottom surface and the longest straight portion of the side wall is used, and the perpendicular to the bottom surface and the longest straight line of the side wall are used as the outer container. The manufacturing method according to claim 8, wherein a cup-shaped container having an internal angle of 1 to 20 ° with the portion is used.   The manufacturing method of Claim 8 or 9 which inclines the opening part side of the side wall of the said outer side container to the said inner side container side.   The manufacturing method according to any one of claims 8 to 10, wherein after the inner container and the outer container are fitted, the adhesive layer is heat-sealed to the inner container and the outer container. The manufacturing method according to claim 11, wherein heating for heat fusion and cooling of a portion other than the portion to be heated are performed simultaneously.

Images