Method for manufacturing laminate type battery

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 technology]

[0002] Patent Document 1 discloses a method for manufacturing a laminated battery, in which an assembly is prepared in which a power generating element is placed between a pair of wide surfaces of a laminated outer casing with the terminals protruding outward, and the edges of the laminated outer casing that sandwich the terminals are welded together while a heated compression member is brought into contact with the assembly. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-128919 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the above manufacturing method, the outer periphery of the laminated outer casing, together with the terminals extending from the inside to the outside of the laminated outer casing, can be welded together by applying pressure with a heated compression member made of an elastic material, thereby allowing the laminated outer casing to be welded without any gaps.

[0005] However, in the above manufacturing method, if the pressure is too weak, gaps may occur at the welded portions at uneven areas such as seams of the laminate film. Furthermore, if the pressure is increased to eliminate the gaps at the welded portions, the metal layers of the laminate films may come into close proximity or contact with each other, resulting in a short circuit. For this reason, this method is particularly difficult to apply to bipolar batteries, which do not allow short circuits between the metal layers of the laminate films.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a method for manufacturing a laminated battery that can produce a high-quality laminated battery 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] In order to achieve the above object, the method for producing a laminated battery of the present invention includes: A method for manufacturing a laminated battery, comprising welding a pair of first laminate films and a pair of second laminate films, each having a metal layer with a resin layer on both sides thereof, together with a welding jig to form a laminate exterior body made of the first laminate films and the second laminate 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 a welding target portion; As the welding jig, a pair of split jigs is used, which sandwich and pressurize the half of each side in the extension direction of the welding target portion while heating it with a pair of heat bars, and weld it, a stopper is provided between the pair of heat bars of the dividing jig to restrict movement in the pressure direction; A step portion is provided on a pressure surface of the pair of heat bars of the dividing jig that presses the welding target portion, where a seam portion where the second laminate film is placed over the first laminate film is to be placed.

[0008] This method of manufacturing a laminated battery uses a dividing jig to weld each half of the welding area, preventing the molten resin from flowing toward the non-welded area, and effectively directing the molten resin into and filling the gap formed at the seam between the first and second laminate films. Furthermore, when welding is performed using the dividing jig, the stopper restricts the movement of the heat bars toward each other. This allows the heat bars to apply an appropriate pressure to the first and second laminate films. This prevents the metal layers from coming too close or coming into contact with each other, which can lead to short circuits. Furthermore, a step is provided on the pressure surface of the heat bar, and the seam between the first and second laminate films is positioned at the step for pressure application. This allows the seam to be welded with the appropriate pressure, preventing the metal layers from coming too close or coming into contact with each other at the seam due to excessive pressure, thereby preventing short circuits. It also ensures that the appropriate amount of resin flows into the gap at the seam. [Effects of the Invention]

[0009] According to the present invention, a method for manufacturing a laminated battery can be provided that can manufacture a high-quality laminated battery by welding laminated films together without gaps while suppressing short circuits between the metal layers of the laminated films. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of a laminated battery manufactured by the manufacturing method according to this embodiment. [Figure 2] FIG. 2 is a perspective view of the seam between the first laminate film and the second laminate film of the laminated battery. [Figure 3] FIG. 3 is a schematic cross-sectional view of a welded portion on the outer periphery of a laminate exterior body. [Figure 4] FIG. 4 is a schematic cross-sectional view showing the structure of the first laminate film and the second laminate film. [Figure 5] FIG. 5 is a schematic cross-sectional view showing a welding jig used when welding the first laminate film and the second laminate film. [Figure 6]FIG. 6 is a schematic cross-sectional view showing the welding procedure using a welding jig. [Figure 7] FIG. 7 is a schematic cross-sectional view showing the welding procedure using a welding jig. [Figure 8] FIG. 7 is a schematic cross-sectional view showing the welding procedure using a welding jig. DETAILED DESCRIPTION OF THE INVENTION

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

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

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

[0014] The laminate exterior body 13 has first laminate films 21a and 21b that cover the front and back of the power generating element at the center in the longitudinal direction, and second laminate films 23a and 23b that cover the front and back of the power generating element at both ends in the longitudinal direction.

[0015] FIG. 4 is a schematic cross-sectional view showing the structure of the first laminate films 21a and 21b and the second laminate films 23a and 23b. As shown in Fig. 4, the first laminate films 21a and 21b are each a metal laminate film having a conductive layer C and a resin layer R provided on both sides of the conductive layer C. The conductive layer C is a film formed from a conductive metal material such as aluminum, and the resin layer R is a film formed from a resin material such as polypropylene or nylon. Similarly, the second laminate films 23a and 23b are each a metal laminate film having a conductive layer C and a resin layer R provided on both sides of the conductive layer C. Note that the second laminate films 23a and 23b may be films having only a resin layer R without a metal layer C.

[0016] The front side of the power generating element is covered by one first laminate film 21a and one second laminate film 23a, and the back side is covered by the other first laminate film 21b and the other second laminate film 23b. These first laminate films 21a, 21b and second laminate films 23a, 23b are welded to each other around the entire periphery of the power generating element. As a result, the power generating element is covered by a laminate exterior body 13 made of the first laminate films 21a, 21b and the second laminate films 23a, 23b. The metal layers C of the first laminate films 21a, 21b are exposed on the top and bottom surfaces of the laminate exterior body 13, and these exposed portions serve as electrodes 15.

[0017] Furthermore, the edges of one of the first laminate films 21a are covered, overlapped, and welded to both longitudinal edges of one of the first laminate films 21a with the edges of one of the second laminate films 23a, and the edges of the other of the first laminate film 21b are covered, overlapped, and welded to both longitudinal edges of the other of the first laminate film 21b with the edges of the other of the second laminate film 23b. This seals the gap between the first laminate films 21a, 21b and the second laminate films 23a, 23b. In this way, a seam 25 is formed around the outer periphery of the power generating element, where the edges of the welded first laminate films 21a, 21b are covered, overlapped, and welded to the edges of the welded second laminate films 23a, 23b.

[0018] The seam 25 has a triangular gap G in a side view, which is formed between the end faces of the first laminate films 21a, 21b that are welded together and the portions of the second laminate films 23a, 23b that extend from the welded portions to the overlapping portions of the first laminate films 21a, 21b. The gap G is filled with and sealed with resin Rm.

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

[0020] As shown in FIG. 5, in this embodiment, the edges along the longitudinal direction of the laminate exterior body 13 are welded using a welding jig 30 at the outer periphery of the power generating element.

[0021] The welding jig 30 is composed of a pair of split jigs 31A and 31B. Each of the split jigs 31A and 31B is composed of a pair of heat bars 33a and 33b. Each of the heat bars 33a and 33b has a heater inside and is arranged facing each other above and below.

[0022] The opposing surfaces of the heat bars 33a and 33b are pressure surfaces 35. The pressure surfaces 35 of the heat bars 33a and 33b are formed with a recessed step portion 47 having a bottom portion 41 and step portions 43 and 45 on both sides of the bottom portion 41.

[0023] The dividing jigs 31A and 31B also have a stopper 51 at one end. This stopper 51 is disposed between the heat bars 33a and 33b and is provided on one of the heat bars 33a. Note that the stopper 51 may also be provided on the other heat bar 33b, or may be provided integrally with either one of the heat bars 33a or 33b.

[0024] Next, a case where the edges along the longitudinal direction of the laminate outer casing 13 are welded using the welding jig 30 will be described. 6 to 8 are schematic cross-sectional views showing the welding procedure using welding jig 30. FIG. 6, the first laminate films 21a, 21b are overlapped with each other, and the second laminate films 23a, 23b are overlapped with each other while covering the edges of the first laminate films 21a, 21b, to form areas to be welded by the welding jig 30. The areas to be welded of the first laminate films 21a, 21b and the second laminate films 23a, 23b are then placed between the heat bars 33a, 33b that constitute the dividing jigs 31A, 31B of the welding jig 30, and the areas to be welded of the first laminate films 21a, 21b and the second laminate films 23a, 23b are clamped and pressurized by the heat bars 33a, 33b.

[0025] Next, the heat bars 33a, 33b of one dividing jig 31A heat one half of the first laminate films 21a, 21b and the second laminate films 23a, 23b in the extension direction at the welding target portions, so that the first laminate films 21a, 21b and the second laminate films 23a, 23b are pressed together while being heated and welded to each other.

[0026] In addition, the seam portions 25 between the first laminate films 21a, 21b and the second laminate films 23a, 23b that are placed over and overlapped on the edges of the first laminate films 21a, 21b are pressed together while being heated by the bottoms 41 of the step portions 47 of the heat bars 33a, 33b of the dividing jig 31A, and are welded together.

[0027] Also, as shown in Figure 7, when welding is performed using the dividing jig 31A, the molten resin Rm of the resin layer R of the first laminate film 21a, 21b and the resin layer R of the second laminate film 23a, 23b flows into the gap G at the seam portion 25, and the gap G is sealed by this resin Rm.

[0028] After welding by one dividing jig 31A, heating by the heat bars 33a, 33b of one dividing jig 31A is stopped, and the remaining half of the extension direction of the welding target portions of the first laminate films 21a, 21b and the second laminate films 23a, 23b is heated by the heat bars 33a, 33b of the other dividing jig 31B. In this way, the first laminate films 21a, 21b and the second laminate films 23a, 23b are pressed together while being heated and welded to each other.

[0029] In addition, the seam 25 between the first laminate film 21a, 21b and the second laminate film 23a, 23b that is placed over and overlapped on the edges of the first laminate film 21a, 21b is pressed against each other while being heated by the bottom 41 of the step portion 47 of the heat bars 33a, 33b of the dividing jig 31B, and is thereby welded together.

[0030] Also, as shown in Figure 8, when welding is performed using the dividing jig 31B, the molten resin Rm of the resin layer R of the first laminate film 21a, 21b and the resin layer R of the second laminate film 23a, 23b flows into the gap G at the seam portion 25, and the gap G is sealed by this resin Rm.

[0031] As described above, according to the method of the present embodiment, split jigs 31A and 31B of welding jig 30 are used to heat and weld one half of the edge along the longitudinal direction of laminate exterior body 13 at a time, so that resin layer R of first laminate films 21a and 21b does not melt in the non-welded regions that are not welded. Therefore, resin Rm of resin layer R of first laminate films 21a and 21b that melts in the welded region is prevented from flowing toward the remaining half of the region on one side, and is properly guided to gap G.

[0032] Furthermore, when the heat bars 33a, 33b are welded by the dividing jigs 31A, 31B, the movement of the heat bars 33a, 33b toward each other is restricted by the stoppers 51. This allows the first laminate films 21a, 21b and the second laminate films 23a, 23b to be clamped by the heat bars 33a, 33b with an appropriate pressure. This prevents the metal layers C from coming into close proximity or contact with each other, which would otherwise be caused by excessive pressure being applied to the first laminate films 21a, 21b and the second laminate films 23a, 23b, thereby preventing short circuits.

[0033] Furthermore, a step portion 47 having steps 43, 45 is provided on the pressure surfaces 35 of the heat bars 33a, 33b, and the seam 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 positioned at the step portion 47 and pressurized. This allows the seam 25 to be clamped with an appropriate pressure, preventing the metal layers C from coming close to or coming into contact with each other at the seam 25 due to excessive pressure, thereby preventing short circuits. Also, the amount of resin Rm flowing into the gap G at the seam 25 can be adjusted to an appropriate amount.

[0034] In the above embodiment, the areas to be welded of the first laminate film 21a, 21b and the second laminate film 23a, 23b are pressurized by a pair of dividing jigs 31A, 31B, and then heated on one side in turn by the heat bars 33a, 33b of each dividing jig 31A, 31B. However, it is also possible to pressurize and heat one half of the areas to be welded by the dividing jig 31A to weld them, and then pressurize and heat the remaining half of the areas to be welded by the dividing jig 31B to weld them. [Explanation of symbols]

[0035] 10 Laminated battery 13 Laminate exterior body 21a, 21b First laminating film 23a, 23b Second laminating film 25 Joint 30 Welding jig 31A, 31B Dividing jig 33a, 33b Heat Bar 35 Pressure Surface 47 Step 51 Stopper C metal layer R resin layer

Claims

[Claim 1] A method for manufacturing a laminated battery, comprising: welding a pair of first laminate films and a pair of second laminate films, each having a metal layer with a resin layer on both sides thereof, together with a welding jig to form a laminate exterior body made of the first laminate films and the second laminate 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 a welding target portion; As the welding jig, a pair of split jigs is used, which sandwich and pressurize the half of each side in the extension direction of the welding target portion while heating it with a pair of heat bars, and weld it, a stopper is provided between the pair of heat bars of the dividing jig to restrict movement in the pressure direction; a step portion is provided on a pressure surface of the pair of heat bars of the dividing jig that presses the welding target portion, where a seam portion where the second laminate film is placed over the first laminate film is to be placed. Manufacturing method for laminated batteries.

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