JP2007311362A - Battery and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery of which a metal terminal is not extruded out of an external cover and which has excellent manufacturing efficiency. <P>SOLUTION: At least one of two external covers made of metal sheets serving as electrodes of a battery has a concave part with a flange part on its peripheral. A power generating element is housed in the concave part and the flange part and the concave part housing the power generating element are covered by the other metal sheet, and two metal sheets are sealed in a thermal bonding with a metal bonding film which is placed under the flange part and is composed of a lamination of a heat resisting resin layer and metal bonding resin layers on both sides of the heat resisting resin layer. At least the external metal cover forming the concave part is made of an annealing treated aluminum foil. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The battery of the present invention and the manufacturing method thereof relate to a new structure of the battery, in particular, a battery that does not require a metal terminal to protrude from an exterior body and a manufacturing method thereof.

  The battery in the present invention means a lithium ion secondary battery, a lithium polymer secondary battery in which lithium ions move between electrodes, or a liquid capacitor, a dielectric capacitor, or a double layer capacitor including a dielectric such as a liquid, a solid ceramic, or an organic substance. The electrolytic type capacitor is shown. Applications of the battery include personal computers, portable terminal devices (cell phones, PDAs, etc.), video cameras, electric vehicles, energy storage batteries, robots, satellites, and the like. As the battery exterior body, a metal can obtained by pressing a metal into a cylindrical or rectangular parallelepiped container, or a laminate made of a composite film obtained by laminating a plastic film, a metal foil or the like into a bag shape. (Hereinafter referred to as an exterior body) was used. There were the following problems as a battery outer package. In a metal can, since the outer wall of the container is rigid, the shape of the battery itself is determined. Therefore, since the hardware side is designed to match the battery, the size of the hardware using the battery is determined by the battery, and the degree of freedom in shape is reduced. Therefore, it tends to use an exterior body made of a laminate material. A battery using a laminate material as an outer package (hereinafter referred to as a packaging battery) has at least a base material layer, a barrier layer, and a sealant layer in terms of the material structure of the outer package from the necessary physical properties, workability, economy, etc. It consists of an adhesive layer that adheres the layers, and an intermediate layer may be provided as necessary. A pouch is formed from the laminated body of the above-described configuration of the battery, or at least one side is press-molded to form a battery storage portion to store the battery body, and the pouch type or embossed type (covering the cover) In the above, a necessary part of each peripheral edge is sealed by heat sealing to obtain a battery.

As shown in FIG. 9A, a battery using a conventional laminate material as an exterior body has a metal terminal 73 protruding from the end of the exterior body. As shown in FIG. 9B, the metal terminal is attached to the power generation element of the battery main body 71 as a positive electrode and a negative electrode, respectively, and when the peripheral edge of the outer package is sealed, the metal terminal is attached to the seal portion of the outer package. If the battery becomes larger and the thickness of the metal terminal increases, the level difference will increase at both ends of the metal terminal, and heat sealing may not be able to seal completely. In the method of heat-sealing the terminal adhesive film 76 to the metal terminal 73 in advance, the metal terminal 73 is heated by the heater 81, and the terminal adhesive film 76 is thermally bonded by pressurization of the crimping head. A welding apparatus 80 (FIG. 10) has been proposed (see, for example, Patent Document 1).
As described above, the metal terminal 73 is complicated to be mounted, and the work is complicated in the sealing of the exterior body. Further, when a plurality of batteries are connected and used, it is necessary to connect the metal terminals 73 of the individual batteries in the package battery. For example, as shown in FIG. 11, the metal terminals 73 of the individual batteries are connected. In some cases, it was necessary to connect by the connecting member 74.
Japanese Patent Application 2001-284273

  An object of the present invention is to provide a battery with high production efficiency and a method for manufacturing the same without causing a metal terminal to protrude from the exterior body.

  The above problems can be solved by the following present invention. That is, according to the first aspect of the present invention, at least one of the two exterior bodies made of metal that also serves as a battery electrode is formed with a recess having a flange on the periphery, and the power generation element is accommodated in the recess. It consists of a heat-resistant resin layer with a metal plate covered with a recess containing the flange and the power generation element, and a metal plate between the two metal layers. The battery comprises a battery that is thermally bonded and sealed with a metal bonding film, wherein the outer body made of metal that forms at least the recess is an annealed aluminum foil. The invention described in claim 2 is characterized in that the two exterior bodies described in claim 1 are made of different metals. The invention according to claim 3 is characterized in that a resin reservoir of a metal bonding film is formed at the outer edge end portion bonded and sealed according to any one of claims 1 to 2. It is. According to a fourth aspect of the present invention, a recess is formed on one of the two outer casings made of metal with an annealed aluminum foil, the recess is filled with a power generation element, and an electrolyte or electrolyte is filled. Then, a metal bonding film made of a laminate in which an opening is formed in a portion located in the concave portion and a metal bonding resin layer laminated on the surface layer on both sides of the opening is sandwiched, and the other exterior body is covered and removed. After the temporary sealing of the entire circumference, the outer peripheral portion of the outer package is cut, and then the main sealing is performed. According to a fifth aspect of the present invention, in the present seal according to the fourth aspect, the two exterior bodies are heated via the metal bonding film by pressure heating using a seal fitting larger than the outer periphery of the exterior body. Bonding is performed, and the metal bonding film is melted to form a resin reservoir at the end of the outer package.

  In the battery of the present invention, a film having metal adhesiveness is sandwiched between different types of metal foils and heat-pressed main sealing is performed. At this time, the seal fitting protrudes from the outer edge welded portion of the exterior body, and heating is applied. The resin film that protruded by pressure bonding was accumulated in the vicinity of the cut end face of the metal foil so as to prevent a short circuit due to the proximity of the metal foils. Since the metal foil of the exterior is in contact with the power generation element enclosed inside, and the current can be directly taken out from the exterior body, it is not necessary to project the metal terminal for current extraction from the exterior body. Since there is no metal terminal for extracting current and there is no need to protrude the metal terminal from the exterior body, the battery outer structure can be simplified. When the metal terminal for taking out the current is protruded from the exterior body, it is necessary to consider the sealing performance around the metal terminal. In the present invention, since there is no current extraction metal terminal, the step of attaching the metal terminal to the power generation element can be omitted, and the manufacturing operation can be continuously performed in multiple rows, so that the production efficiency is good. In the case of combining a plurality of batteries, in the conventional structure, it is necessary to join the respective metal terminals by some means. However, in this embodiment, the joining of the individual batteries can be obtained simply by overlapping, and the structure can be simplified.

  In the present invention, at least one of the two exterior bodies made of metal is formed with a recess having a flange at the periphery, the power generation element is stored in the recess, and the recess having the flange and the power generation element stored in the other metal plate Is covered with a metal bonding film interposed between the two metals in the flange portion and sealed, and does not require a metal terminal to protrude from the outer package for current extraction. Hereinafter, it will be described in more detail with reference to the drawings.

  1A and 1B are diagrams for explaining an embodiment of a battery according to the present invention. FIG. 1A is a perspective view of the battery, FIG. 1B is a cross-sectional view of the X1-X1 portion, and FIG. Sectional drawing which shows the state made to do, (d) is sectional drawing of the exterior body except a power generation element. FIG. 2 is a conceptual diagram of a production line showing an embodiment up to provisional seal punching of the battery production method of the present invention. FIG. 3 is a conceptual diagram of the seal part. FIG. 4 is a cross-sectional view of a layer configuration illustrating an example of an adhesive film. FIG. 5 is an enlarged cross-sectional view of the end Y1 to be sealed, (a) before pressurization, (b) start of pressurization and heating by the seal fitting, (c) pressurize and heat state, (d) The seal end state is shown. FIG. 6 is a perspective view showing a state in which a molded metal foil is formed by multiple imposition in the manufacturing process of the battery of the present invention. FIG. 7 is a front view showing a state in which a metal bonding film is punched out in multiple faces in the battery manufacturing process of the present invention. FIG. 8 is a perspective view showing a state in which the batteries of the present invention are connected in series.

  In the battery of the present invention, a concave portion 5 having a flange portion 4 is formed around at least one of two metal plates (hereinafter referred to as a molded metal foil M1), the power generating element 2 is accommodated in the concave portion, and the other metal plate. (Hereinafter, the lid metal foil M2) covers the flange portion 4 and the recess 5 in which the power generation element 2 is accommodated, and the metal bonding film 10 interposed between the two metal foils and interposed in the flange portion 4 is thermally bonded. And sealed. In addition, the metal plate in this invention shows plate shape, sheet shape, foil shape, etc. The two metal plates may be the same or different depending on the type of battery. In the case of a lithium ion secondary battery, metal plates of different materials are used as the positive electrode and the negative electrode. And the battery of this invention makes it the shape without the output terminal which protruded on the outer side of the exterior body attached in the battery by the conventional film exterior body by using two metal foils as the exterior body of a battery. Can do. Furthermore, by forming one metal plate as a recess, the power generation element can be accommodated in the recess, and this is covered with the other metal plate, so that the flatness of the electrode surfaces on both metal plates is obtained. easy. The formed metal foil M1 forming the concave portion 5 is preferably an aluminum foil because it is excellent in formability and is less expensive than other metals.

  In addition, aluminum produced by cold rolling changes its flexibility, waist strength and hardness under annealing (so-called annealing treatment) conditions, but the aluminum used in the present invention is harder than the non-annealed hard-treated product. Aluminum which tends to be soft with some or complete annealing is preferred. The degree of flexibility, waist strength and hardness of the aluminum, that is, the conditions for annealing, may be appropriately selected according to the shape of the recess to be molded and the suitability for molding. For example, in order to prevent wrinkles and pinholes at the time of forming the recess, it is desirable to use soft aluminum annealed according to the degree of molding.

  In particular, in lithium ion secondary batteries, aluminum functions as the positive electrode of the battery, and the metal that becomes the negative electrode, that is, the lid metal M2 in the present invention is copper, nickel, nickel-plated copper, iron, stainless steel, etc. Can be used. An appropriate thickness of the molded metal foil M1 is 30 to 300 μm, and an appropriate thickness of the lid metal foil M2 is 20 to 100 μm.

  In the battery of the present invention, the molded metal foil M1 and the lid metal foil M2 are bonded to each other at a predetermined location with a metal bonding film interposed therebetween. The bonding method is heat sealing, ultrasonic wave, high frequency. However, a welding method by heat sealing is preferable, and a welding film is preferable as the metal bonding film. In the present invention, in the state where the formed metal foil M1 and the lid metal foil M2 are bonded, the metal bonding film is provided with an extension portion 7 extended at least 2 mm from the bonded inner edge to the center side of the recess. The presence of the extension 7 prevents the molded metal foil M1 and the cover metal foil M2 from contacting and shorting in the battery.

  In addition, as shown in FIG. 1B, it is desirable to form a resin reservoir 8 of a metal bonding film on the outer end portion of the battery seal portion. The resin reservoir 8 can be formed by setting the shape of the seal fitting 61 and the pressure and heating conditions in the heat sealing process described later. However, due to the presence of the resin reservoir 8, the molded metal foil M1 is formed at the outer edge of the battery. And the cover metal foil M2 are prevented from coming into contact and short-circuiting. The same effect can be obtained by chemically retreating the metal foil outer peripheral portion 9 to leave a metal bonding film. This is shown in FIG.

  In the battery of the present invention, when the molded metal foil M1 and the lid metal foil M2 are bonded together with a metal bonding film interposed therebetween, for example, if the metal bonding film is only the metal bonding resin layer, the pressure applied by the seal fitting It melts by heating and is extruded to both ends of the seal portion. Depending on conditions, a portion without a metal bonding film is formed between the molded metal foil M1 and the lid metal foil M2, and the molded metal foil M1 and the lid metal foil M2 may come into contact. As a result of studying the metal bonding film in which the metal bonding film remains as an insulating layer between the molded metal foil M1 and the lid metal foil M2 even by the pressure heating of such heat seal, It has been found that the above-mentioned problems can be solved by making the adhesive film have a multilayer structure including at least a heat-resistant resin layer and a metal adhesive resin layer. For example, as shown in FIG. 4A, a three-layer configuration of a metal adhesive resin layer 12, a heat resistant resin layer 11, and a metal adhesive resin layer 12, or as shown in FIG. The intermediate adhesive resin layer 13, the heat resistant resin layer 11, the intermediate adhesive resin layer 13, and the metal adhesive resin layer 12 are used. As a method of welding the formed metal foil M1 and the lid metal foil M2 with the metal bonding film 10 interposed, any method such as a heat sealing method, an ultrasonic sealing method, a high frequency sealing method, etc. may be used. The method is preferably used.

  The resin forming the heat-resistant resin layer 11 in the metal bonding film 10 is a metal bonding resin layer 12 of the metal bonding film 10 by pressure heating with a seal fitting when welding the molded metal foil M1 and the lid metal foil M2. Is a film or resin having heat resistance that can maintain the film shape as an insulating film even if it melts, for example, a film such as a biaxially stretched polyester film, a biaxially stretched polyamide film, or a biaxially stretched polypropylene film, or As a simple substance such as medium density polyethylene, high density polyethylene, polypropylene, cross-linked polyolefin resin, polyethylene naphthalate resin, 4-methyl-1-pentene polymer, or a blend resin of two or more of these resins or other resins Good.

Further, the metal adhesive resin layer 12 in the metal bonding film 10 is a layer made of a resin that can be welded to the molded metal foil M1 and / or the lid metal foil M2,
(1) Unsaturated carboxylic acid graft-modified α-olefin polymer and α-olefin copolymer (2) Copolymer of ethylene and acrylic acid or acrylic acid derivative,
(3) a copolymer of ethylene and methacrylic acid or a methacrylic acid derivative;
(4) It is selected from α-olefin polymers cross-linked with metal ions or copolymers of ethylene and α-olefins.

  Next, the manufacturing method of the battery 1 of the present invention will be described. The battery of the present invention can be manufactured, for example, using an apparatus as shown in FIGS. First, as shown in FIG. 2, the formed metal foil M <b> 1 is fed out and press-formed by the forming punch 21 and the forming die 22 in the metal forming portion 20, thereby forming the recess 5. Next, the power generation element 2 is filled in the recess 5. As shown in FIG. 7, the metal bonding film 10 drawn out from the wide winding is punched out by the punching punch 31 and the punching die 32 at the film punching portion 30 and filled with the power generation element 2. It superposes | polymerizes in the state which synchronizes with the recessed part 5 in which the said extraction part 10W was shape | molded on the web of the shape | molded metal foil M1. Subsequently, the electrolytic solution or the electrolytic substance is filled from the opening, and the whole is covered with the cover metal foil M2 fed out from the winding, and then, in the deaeration temporary seal part 40, the deaeration after sealing is temporarily performed by the seal fitting 41. Seal. An electrolytic substance may be applied to the power generation element in advance, and in this case, filling of the electrolytic substance can be omitted. Next, the temporarily sealed battery 1N is obtained by punching to a predetermined dimension.

  Next, the temporarily sealed battery 1N is supplied to a main seal portion 60 as shown in FIG.

  Partial enlarged views of the seal portion Y1 in the present seal are shown in FIGS. The seal fitting 61 of this seal portion is provided with a seal fitting extension 62 that is longer than the outer edge of the temporarily sealed battery 1N. By providing the seal fitting extension 62, when heat-sealing, the metal bonding film is pressurized and heated, and the metal adhesive resin layer in the structure extends from the end along the surface of the seal fitting extension 62. Then, the resin reservoir 8 is formed by being pushed outward, and when the resin reservoir 8 is cooled and solidified, the tip thereof becomes substantially parallel to the end face.

  It should be noted that it is desirable that the surface of the seal fitting 61 is subjected to an easy peeling treatment or an easy peeling tape so that the resin extruded from the end portion does not adhere to the seal fitting 61.

  Due to the presence of the formed resin reservoir 8, a short circuit due to the proximity of the formed metal foil M1 and the lid metal foil M2 at the end of the battery 1 can be avoided.

  As described above, according to the battery of the present invention and the manufacturing method thereof, the metal foil of the exterior is in contact with the power generation element enclosed inside, and the current can be directly taken out from the exterior body. There is no need to protrude the metal terminal from the exterior body. Since there is no metal terminal for extracting current, the step of attaching the metal terminal to the power generation element can be omitted.

  In a packaged battery in which a metal terminal for current extraction is projected from the exterior body, it is necessary to consider the sealing performance around the metal terminal, but since the metal terminal does not project in this embodiment, the battery outer structure can be simplified and its manufacture is also possible. It becomes easy.

  When combining a plurality of batteries, it is necessary to join the respective metal terminals by some means in the conventional structure. However, in the battery structure of the present invention, as shown in FIG. Connection between batteries is obtained, and the serial connection structure can be simplified. Moreover, when it is set as such a connection structure, since the plane is obtained with a large area, it is suitable for the form of the battery of this invention. In this embodiment, manufacturing operations can be performed continuously, and as shown in FIG. 6, for example, forming of the molded metal foil M1, and multi-row processing such as punching of the metal bonding film 10 as shown in FIG. This is possible and does not require a metal terminal mounting step, etc., so that it is streamlined as a production line and has high production efficiency.

  The battery of the present invention will be described more specifically with reference to examples.

Aluminum foil (thickness, 100 μm) was used as the molded metal foil, and copper foil (thickness, 30 μm) was used as the lid metal. As a metal bonding film, the layer thickness was set to 100 μm as the next layer configuration.
Acid-modified polypropylene (PPa, thickness 25 μm) / TPX blend resin (thickness, 15 μm) / TPX resin (thickness, 20 μm) / TPX blend resin (thickness, 15 μm) / acid-modified polypropylene (PPa, thickness 25 μm)
{TPX: 4-methyl-pentene polymer, TPX blend: blend of 4-methyl-pentene and butene copolymer resin and ethylene-propylene copolymer resin in equal amounts}
Heat seal is made of metal foil 1 / metal bonding film / metal foil 2 (total thickness 230 μm), and the surface of the metal fitting is 7mm wide, the seal part length is 150mm, the temperature of the metal fitting The upper and lower surfaces were heated at 190 ° C., the sealing time was 3 seconds, and the three sides were temporarily sealed at a sealing pressure of 0.36 MPa. The total thickness of the seal part after temporary sealing is 225 μm.
Next, the outer peripheral portion was cut along the seal edge, and a seal leak check penetrant was introduced from one open side of the seal portion. After 2 hours, the seal portion was peeled off, and it was confirmed that there was no penetration into the seal portion.
The same seal fitting as above is used, the seal width is 5 mm (the seal fitting protrudes 2 mm from the outer edge of the material), the seal part length is 150 mm, the seal fitting temperature is 190 ° C., heating up and down, the sealing time is 3 seconds, and the sealing pressure is 0.72 MPa. It was. Total thickness of the seal part 202-206μ
m.
<Result>
A resin reservoir having a length of 0.7 mm was formed at the outer edge of the seal portion, and at this time, the molded metal foil and the lid metal foil were not short-circuited.
In addition, 19-25N (average 23N) per 15 mm width was obtained as peeling strength of a seal part.

The difference in moisture permeability with and without a metal terminal was confirmed with a packaging battery.
Material Ny25μm / Aluminum 40μm / EL15μm / PP30μm
An aluminum plate (thickness, 0.5 mm, width, 20 mm) was used as the metal terminal.
A pouch with a seal width of 5 mm and an inner dimension of 100 × 100 mm is used. A metal terminal is sandwiched between one side of the seal side with the same film as the metal bonding film interposed therebetween. After heat sealing, 5 g of electrolyte was filled from the open side, and the open side was heat sealed and sealed.
As a comparison, a pouch sealed with 5 g of electrolyte was prepared without sandwiching the metal terminal.
{Electrolytic solution: Mixed solution of ethylene carbonate, diethyl carbonate, and dimethyl carbonate (1: 1: 1) so as to be 1M LiPF6}
The obtained pouch sealed with a metal terminal sandwiched and a sealed pouch sealed without a metal terminal sandwiched in an environment of 60 ° C. and 90% RH for 50 days were measured for moisture permeation.
The results were as follows.
Moisture permeation amount when metal terminal is used: 400PPM
When there was no metal terminal: 345 PPM.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the Example of the battery of this invention, (a) is a perspective view of a battery, (b) is sectional drawing of a X1-X1 part, (c) The state which retreated the metal foil outer periphery periphery part Sectional drawing shown, (d) is a sectional view of the exterior body excluding the power generation element. It is a conceptual diagram of the manufacturing line which shows the Example until temporary seal punching of the manufacturing method of the battery of this invention. It is a conceptual diagram of this seal part. It is sectional drawing of the layer structure explaining the Example of an adhesive film. In the enlarged cross-sectional view of the end Y1 to be sealed, (a) before pressurization, (b) start of pressurization and heating by the seal fitting, (c) pressurization and heating state, (d) shows the seal end state. Show. In the manufacturing process of the battery of this invention, it is a perspective view which shows the state which shape | molded the shaping | molding metal foil by multiple imposition. In the manufacturing process of the battery of this invention, it is a front view which shows the state which carried out the punching process by the multifaceted film for metal bonding. It is a perspective view which shows the state which connected the battery of this invention in series. It is a figure explaining the Example of the battery which consists of an exterior body of the laminate material by a prior art, (a) is a perspective view, (b) is a battery main body. It is a figure explaining welding to the metal terminal of the adhesive film by a prior art, (a) is a welding apparatus, (b) is a top view of the metal terminal which welded the adhesive film, (c) is X2-. It is sectional drawing of a X2 part. It is a perspective view which shows the state which connected the conventional battery in series.

Explanation of symbols

M1 Molded metal foil M2 Lid metal foil 1 Battery 1N Temporarily sealed battery 2 Power generation element 3 Electrolytic solution or electrolytic substance 4 Flange part 5 Recessed part 6 Seal part 7 Extension part 8 Resin reservoir 9 Peripheral peripheral part 10 Metal bonding film 10W Part 11 Heat Resistant Resin Layer 12 Metal Adhesive Resin Layer 13 Intermediate Layer 20 Metal Molding Part 21 Molding Punch 22 Molding Die 30 Film Punching Part 31 Punching Punch 32 Punching Die 40 Temporary Sealing Part 41 Seal Fitting 50 Battery Perimeter Punching Part 51 Punching Punch 52 Punching Die 50W Unremoved portion 60 Seal portion 61 Seal fitting 62 Seal fitting extension 70 Battery using exterior body made of laminate material 71 Battery body 72 Power generation element 73 Metal terminal 73m Metal terminal 73a with terminal adhesive film adhered Positive electrode Metal terminal 73b Negative metal terminal 74 Connecting member 7 Welding device terminals adhesive film 77 sealing portion 80 adhesive film 81 heater 82 heating block 83 bonding head 83g heat rubber 84 heat seal bars

Claims (5)

At least one of the two exterior bodies made of metal that also serves as the electrode of the battery is formed with a recess having a flange portion at the periphery, the power generation element is stored in the recess, and the flange portion and the power generation element are stored in the other metal plate. Covered with a recess, heat-adhered and sealed by a metal adhesive film consisting of a heat-resistant resin layer and a metal adhesive resin layer laminated on the surface of both surfaces, with a flange between two sheets of metal. What is claimed is: 1. A battery according to claim 1, wherein the outer casing made of a metal forming at least the recess is an annealed aluminum foil. The battery according to claim 1, wherein the two exterior bodies are made of different metals. 3. The battery according to claim 1, wherein a resin reservoir portion of a metal bonding film is formed at an outer edge end portion bonded and sealed. A recess is formed in one of the two outer casings made of metal with an annealed aluminum foil, and the recess is filled with a power generation element, filled with an electrolytic solution or an electrolyte, and opened in a portion located in the recess. After forming a heat resistant resin layer and a metal adhesive film consisting of a laminate of metal adhesive resin layers on the surface of both sides, the other exterior body is covered, degassed, and temporarily sealed all around, then the exterior A method for manufacturing a battery, comprising cutting an outer periphery of a body and then performing a main seal. The main seal is formed by heat-bonding two exterior bodies through the metal bonding film by pressurization and heating using a seal fitting larger than the outer periphery of the exterior body, and melting the metal adhesion film. The battery manufacturing method according to claim 4, wherein a resin reservoir is formed at the end.

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