Manufacturing method for laminated batteries

Abstract

To provide a method for producing a laminate type battery capable of producing a high quality laminate type battery by welding laminate films to each other without a gap while suppressing a short circuit between metal layers of the laminate film.SOLUTION: As a welding jig 30, a pair of dividing jigs 31A and 31B are used in which one half in an extending direction of a welding target portion of a laminate exterior body 13 is sandwiched by a pair of heat bars 33a and 33b while being heated and pressurized to be welded, and a stopper 51 for restricting the movement in a pressurizing direction is provided between the pair of heat bars 33a and 33b of the dividing jigs 31A and 31B. A step part 47 in which a joint part 25 formed by covering and overlapping first laminate films 21a and 21b with second laminate films 23a and 23b is disposed is provided on a pressurizing surface 35 for pressurizing the welding target portions of the pair of heat bars 33a and 33b of the dividing jigs 31A and 31B.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a laminated battery.

Background Art

[0002] Patent Document 1 discloses, as a method for manufacturing a laminated battery, a method in which an assembly having a power generation element disposed between a pair of wide surfaces of a laminated exterior body with terminals protruding outward is prepared, and with a heating and pressing member in contact with the assembly, the edge portion of the laminated exterior body that sandwiches the terminals is welded.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] According to the above manufacturing method, the outer peripheral portion of the laminated exterior body together with the terminals extending from the inside to the outside of the laminated exterior body is pressed and welded by the heating and pressing member made of an elastic body, whereby welding can be performed without gaps.

[0005] However, in the above manufacturing method, if the pressing force is weak, there is a risk that gaps may occur at the welded portions at steps such as the joint of the laminated films. In addition, if the pressing force is increased to eliminate the gaps in the welded portions, the metal layers of the laminated films to be bonded may approach or contact each other, leading to a risk of short circuit. For this reason, it is particularly difficult to apply the method to bipolar batteries where short circuits between the metal layers of the laminated films are not permitted.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a method for manufacturing laminated batteries that can produce high-quality laminated batteries by welding laminated films together without gaps while suppressing short circuits between the metal layers of the laminated films. [Means for solving the problem]

[0007] To achieve the above objective, the manufacturing method of the laminate-type battery of the present invention is as follows: A manufacturing method for producing a laminated battery, comprising welding together a pair of first laminated films and a pair of second laminated films, each having a resin layer on both sides of a metal layer, using a welding jig to form a laminated outer casing consisting of the first laminated films and the second laminated films, The pair of first laminate films and the pair of second laminate films are overlapped with each other, and the second laminate film is placed over the overlapped pair of first laminate films to form the area to be welded. As the welding jig, a pair of split jigs are used to heat and clamp each half of the area to be welded in the extending direction using a pair of heat bars, and then pressurize and weld it. A stopper is provided between the pair of heat bars of the dividing jig to restrict movement in the pressurizing direction. A stepped portion is provided on the pressure surface of the pair of heat bars of the dividing jig that applies pressure to the welding target area, where the seam formed by overlapping the first laminate film with the second laminate film is positioned.

[0008] According to this method for manufacturing laminate-type batteries, the welding jig is used to weld only one half of the area to be welded in the direction of extension. This prevents the molten resin from flowing from the welding area towards the non-welded area. Therefore, the molten resin can be effectively guided and filled into the gap formed at the joint between the first laminate film and the second laminate film. Furthermore, when welding using the splitting jig, the stopper restricts the movement of the heat bars toward each other. This allows the heat bars to pressurize the first and second laminate films with the appropriate pressure. Therefore, it is possible to suppress short circuits by preventing the metal layers from coming into close proximity or contact with each other due to excessive pressure on the first and second laminate films. Furthermore, a stepped section is provided on the pressurizing surface of the heat bar, and the joint between the first laminate film and the second laminate film is positioned on this stepped section and pressurized. This allows the joint to be pressed and welded with the appropriate pressure, and even at the joint, excessive pressure can prevent the metal layers from coming into close proximity or contact, thereby suppressing short circuits. In addition, the amount of resin flowing into the gap at the joint can be adjusted to the appropriate level. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a method for manufacturing laminated batteries that can produce high-quality laminated batteries by welding laminated films together without gaps while suppressing short circuits between the metal layers of the laminated films. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a perspective view of a laminated battery manufactured by the manufacturing method according to this embodiment. [Figure 2] Figure 2 is a perspective view of the seam between the first and second laminate films of a laminate-type battery. [Figure 3] Figure 3 is a schematic cross-sectional view of the welded areas on the outer periphery of the laminated exterior. [Figure 4] Figure 4 is a schematic cross-sectional view showing the structure of the first laminate film and the second laminate film. [Figure 5] Figure 5 is a schematic cross-sectional view showing a welding jig used when welding the first laminate film and the second laminate film together. [Figure 6]Figure 6 is a schematic cross-sectional view showing the welding procedure using a welding jig. [Figure 7] Figure 7 is a schematic cross-sectional view showing the welding procedure using a welding jig. [Figure 8] Figure 7 is a schematic cross-sectional view showing the welding procedure using a welding jig. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 is a perspective view of a laminated battery 10 manufactured by the manufacturing method according to this embodiment. Figure 2 is a perspective view of the joint 25 between the first laminated films 21a, 21b and the second laminated films 23a, 23b of the laminated battery 10. Figure 3 is a schematic cross-sectional view of the welded area on the outer periphery of the laminated outer casing 13.

[0012] As shown in Figures 1 to 3, the laminate-type battery 10 manufactured by the manufacturing method according to this embodiment is, for example, a lithium-ion secondary battery. The manufacturing method according to this embodiment is not limited to lithium-ion secondary batteries, but can also be applied to the manufacture of nickel-metal hydride batteries, nickel-cadmium batteries, and other energy storage elements such as all-solid-state batteries and electric double-layer capacitors using solid electrolytes.

[0013] The laminated battery 10 is, for example, a large-sized bipolar battery. This laminated battery 10 has a structure in which a power generation element consisting of multiple stacked cells (not shown) is sealed in a laminated casing 13, and electrodes 15 are provided on the front and back surfaces of the laminated casing 13. One side of the electrodes 15 on the front and back surfaces is the positive electrode and the other side is the negative electrode.

[0014] The laminated outer casing 13 includes a first laminate film 21a, 21b that covers both sides of the power generation element at the center in the longitudinal direction, and a second laminate film 23a, 23b that covers both sides of the power generation element at both ends in the longitudinal direction.

[0015] Figure 4 is a schematic cross-sectional view showing the structures of the first laminate films 21a, 21b and the second laminate films 23a, 23b. As shown in Figure 4, each of the first laminate films 21a, 21b is a metal laminate film having a conductive layer C and resin layers R provided on both surfaces of the conductive layer C. The conductive layer C is, for example, a film formed of a conductive metal material such as aluminum, and the resin layer R is, for example, a film formed of a resin material such as polypropylene or nylon. Similarly, each of the second laminate films 23a, 23b is a metal laminate film having a conductive layer C and resin layers R provided on both surfaces of the conductive layer C. Note that as the second laminate films 23a, 23b, a film consisting only of the resin layer R without the metal layer C may be used in some cases.

[0016] The power generation element has its front surface side covered by one first laminate film 21a and one second laminate film 23a, and its back surface side covered by the other first laminate film 21b and the other second laminate film 23b. The first laminate films 21a, 21b and the second laminate films 23a, 23b are welded over the entire circumference in the circumferential direction at the outer peripheral portion of the power generation element. Thereby, the power generation element is covered by a laminate exterior body 13 composed of the first laminate films 21a, 21b and the second laminate films 23a, 23b. In the top and bottom surfaces of the laminate exterior body 13, the metal layers C of the first laminate films 21a, 21b are exposed, and these exposed portions serve as the electrodes 15.

[0017] Furthermore, the edges of one of the first laminate films 21a are overlapped and welded together by the edges of one of the second laminate films 23a, and the edges of the other first laminate film 21b are overlapped and welded together by the edges of the other second laminate film 23b, and the edges of the other first laminate film 21b are overlapped and welded together by the edges of the other second laminate film 23b. This seals the space between the first laminate films 21a, 21b and the second laminate films 23a, 23b. In this way, a seam 25 is formed on the outer periphery of the power generation element, where the edges of the first laminate films 21a, 21b, which are welded together, are overlapped and welded together by the edges of the second laminate films 23a, 23b, which are welded together by the edges of the first laminate films 21a, 21b, which are welded together by the edges of the first laminate films 21a, 21b, which are welded together by the edges of the second laminate films 23a, 23b, which are welded together by the edges of the first laminate films 21a, 21b, which are welded together by the edges of the first3a, 23b, which are welded together by the edges of the first laminate films 23a, 23b, which are welded together by the edges of the first laminate films 21a, 21b, and 23b

[0018] The joint portion 25 has a triangular gap G in side view, which is formed by the end faces of the first laminate films 21a and 21b that are welded together, and the portion of each second laminate film 23a and 23b that is overlapped and placed over the first laminate films 21a and 21b from the welding points between them. This gap G is filled and sealed with resin Rm.

[0019] Figure 5 is a schematic cross-sectional view showing a welding jig 30 used when welding the first laminating films 21a, 21b and the second laminating films 23a, 23b.

[0020] As shown in Figure 5, in this embodiment, the edges of the laminated outer casing 13 along the longitudinal direction are welded to the outer periphery of the power generation element using a welding jig 30.

[0021] The welding jig 30 consists of a pair of split jigs 31A and 31B. Each of the split jigs 31A and 31B consists of a pair of heat bars 33a and 33b. These heat bars 33a and 33b each have a heater inside and are arranged facing each other vertically.

[0022] The heat bars 33a and 33b have opposing surfaces that serve as pressure surfaces 35. The pressure surfaces 35 of these heat bars 33a and 33b have a concave stepped portion 47 formed thereon, which has a bottom portion 41 and stepped portions 43 and 45 on both sides of the bottom portion 41.

[0023] Furthermore, the splitting jigs 31A and 31B each have a stopper 51 at one end. This stopper 51 is positioned between the heat bars 33a and 33b and is provided on one of the heat bars 33a. The stopper 51 may also be provided on the other heat bar 33b, or it may be integrally provided on either heat bar 33a or 33b.

[0024] Next, we will describe the case in which the edges of the laminate exterior 13 are welded along the longitudinal direction using the welding jig 30. Figures 6 to 8 are schematic cross-sectional views showing the welding procedure using the welding jig 30. As shown in Figure 6, the first laminate films 21a and 21b are overlapped, and the second laminate films 23a and 23b are overlapped so as to cover the edges of the first laminate films 21a and 21b, thereby forming the areas to be welded by the welding jig 30. These areas to be welded on the first laminate films 21a and 21b and the second laminate films 23a and 23b are then placed between the heat bars 33a and 33b that make up the respective dividing jigs 31A and 31B of the welding jig 30, and the areas to be welded on the first laminate films 21a and 21b and the second laminate films 23a and 23b are clamped and pressed by these heat bars 33a and 33b.

[0025] Next, the heat bars 33a and 33b of one of the splitting jigs 31A heat one half of the extending direction of the first laminate film 21a, 21b and the second laminate film 23a, 23b at the welding target locations. In this way, the first laminate film 21a, 21b and the second laminate film 23a, 23b are heated and pressed together, welding them to each other.

[0026] Furthermore, the joint portion 25 between the first laminate films 21a, 21b and the second laminate films 23a, 23b, which are overlapped and placed over the edges of the first laminate films 21a, 21b, is heated and pressed against each other by the bottom portion 41 of the stepped portion 47 of the heat bar 33a, 33b of the dividing jig 31A, and is welded to each other.

[0027] Furthermore, as shown in Figure 7, when welding is performed by the splitting jig 31A, the molten resin Rm of the resin layer R of the first laminate films 21a, 21b and the resin layer R of the second laminate films 23a, 23b flows into the gap G at the joint 25, and this resin Rm seals the gap G.

[0028] After welding by one of the splitting jigs 31A, heating by the heat bars 33a and 33b of the splitting jig 31A is terminated, and the remaining half of the extending side in the welding direction of the first laminate film 21a, 21b and the second laminate film 23a, 23b is heated by the heat bars 33a and 33b of the other splitting jig 31B. In this way, the first laminate film 21a, 21b and the second laminate film 23a, 23b are heated and pressed together, welding them to each other.

[0029] Furthermore, the joint portion 25 between the first laminate films 21a, 21b and the second laminate films 23a, 23b, which are overlapped and placed over the edges of the first laminate films 21a, 21b, is heated and pressed against each other by the bottom portion 41 of the stepped portion 47 of the heat bar 33a, 33b of the dividing jig 31B, and is welded to each other.

[0030] Furthermore, as shown in Figure 8, when welding is performed by the splitting jig 31B, the molten resin Rm of the resin layer R of the first laminate films 21a, 21b and the resin layer R of the second laminate films 23a, 23b flows into the gap G at the joint 25, and this resin Rm seals the gap G.

[0031] As described above, according to the method of this embodiment, the divided jigs 31A and 31B of the welding jig 30 are used to heat and weld one half at a time along the longitudinal direction of the edge of the laminate exterior 13. Therefore, the resin layer R of the first laminate films 21a and 21b does not melt in the non-welded areas. Consequently, the flow of the resin Rm of the resin layer R of the first laminate films 21a and 21b that melts in the welded areas is suppressed, and it is guided well into the gap G.

[0032] Furthermore, when welding is performed using the splitting jigs 31A and 31B, the movement of the heat bars 33a and 33b toward each other is restricted by the stopper 51. As a result, the first laminate films 21a and 21b and the second laminate films 23a and 23b are held between the heat bars 33a and 33b with appropriate pressure. This prevents the metal layers C from coming into close proximity or contact with each other due to excessive pressure on the first laminate films 21a and 21b and the second laminate films 23a and 23b, thereby suppressing short circuits.

[0033] Furthermore, a stepped portion 47 having stepped portions 43 and 45 is provided on the pressurizing surface 35 of the heat bars 33a and 33b, and the joint portion 25 between the first laminate films 21a and 21b and the second laminate films 23a and 23b, which are overlapped and placed over the edges of the first laminate films 21a and 21b, is positioned on the stepped portion 47 and pressurized. As a result, the joint portion 25 is held by appropriate pressure, and even at this joint portion 25, proximity or contact between the metal layers C due to excessive pressure can be suppressed, thereby preventing short circuits. In addition, the amount of resin Rm flowing into the gap G at the joint portion 25 can be made appropriate.

[0034] In the above embodiment, the welding targets of the first laminate films 21a, 21b and the second laminate films 23a, 23b were pressurized using a pair of splitting jigs 31A and 31B, and then heated one side at a time using the heat bars 33a and 33b of each splitting jig 31A and 31B. However, it is also possible to pressurize and heat one half of the welding target using splitting jig 31A to weld it, and then pressurize and heat the remaining half of the welding target using splitting jig 31B to weld it. [Explanation of symbols]

[0035] 10 Laminated batteries 13. Laminated outer casing 21a, 21b First laminating film 23a, 23b Second laminating film 25. Joint 30 Welding jigs 31A, 31B Splitting jig 33a, 33b Heat Bar 35 Pressure surface 47 Stepped section 51 Stopper C metal layer R resin layer

Claims

[Claim 1] A manufacturing method for a laminated battery, comprising: welding a pair of first laminate films, each having a resin layer on both sides of a metal layer, to each other using a welding jig; welding a pair of second laminate films, wherein the edge of one of the pair of second laminate films is placed over and overlapped with the edge of one of the pair of first laminate films and welded together; the edge of the other of the pair of second laminate films is placed over and overlapped with the edge of the other of the pair of first laminate films and welded together; and the pair of second laminate films are placed over and overlapped with each other so as to surround the periphery of the pair of first laminate films, thereby forming a laminated outer casing made of these first laminate films and second laminate films, the method being used to manufacture a laminated battery, The pair of first laminate films are overlapped, and the edges of the pair of second laminate films are placed over the edges of the overlapped pair of first laminate films to form a welding area. As the welding jig, a pair of split jigs are used to heat and clamp each half of the area to be welded in the extending direction using a pair of heat bars, and then pressurize and weld it. A stopper is provided between the pair of heat bars of the dividing jig to restrict movement in the pressurizing direction. A stepped portion is provided on the pressure surface of the pair of heat bars of the dividing jig that applies pressure to the welding target area, where the seam formed by overlapping the pair of first laminate films with the pair of second laminate films is positioned. Manufacturing method for laminated batteries.

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