JP7388287B2 - Electrode unit manufacturing method - Google Patents

Description

One aspect of the present invention relates to a method of manufacturing an electrode unit.

As a secondary battery, a bipolar battery described in Patent Document 1 is known. In this bipolar battery, bipolar electrodes in which a positive electrode is formed on one surface of a current collector and a negative electrode is formed on the other surface are stacked with an electrolyte layer interposed therebetween. An insulating seal layer is provided between the current collectors.

Japanese Patent Application Publication No. 2005-190713

The separator included in the electrolyte layer allows the electrolyte to pass through, and is placed between adjacent current collectors (electrode plates) to prevent short circuits between them. A gap may exist between the separator and the resin seal layer (frame body) in a direction intersecting the stacking direction. In this case, there is a possibility that a short circuit between adjacent electrode plates may occur through the gap. Therefore, in the bipolar battery as described above, it is required to appropriately arrange a separator between the electrode plates.

One aspect of the present invention is to provide a method for manufacturing an electrode unit in which a separator can be appropriately arranged between electrode plates.

A method for manufacturing an electrode unit according to one aspect of the present invention includes a sheet body arrangement step of arranging a resin sheet body along the edge of each side of a rectangular electrode so as to overlap each corresponding side; A frame bonding step in which the arranged sheet body is bonded to the electrode to form an electrode with a substantially rectangular frame constituted by the sheet body; At the same time, small holes are intermittently drilled between adjacent cut parts of the frame to form perforations for folding. A cutting process to form a score line, and a folding process in which the portion outside the perforation cut line is folded inward along the perforation cut line in the extending portion on each side of the rectangular frame-shaped frame. and a shaping step of heating the folded portion of the folded frame while pressing it in the thickness direction.

In the above manufacturing method, cut portions and perforation-like incision lines are formed in the frame formed by the sheet bodies arranged on each side of the electrode. By folding back the frame along the perforated cut line, the frame is partially formed double. Since the perforated cut line is formed between the cut parts, the double portion of the frame can form a rectangular shape. By pressing and heating the folded frame body, the frame body is bent in the folded state. A separator may be appropriately placed in the inner portion of the frame folded back into a rectangular shape. In this method, since the cut portion and the perforation-like score line are formed in the same process, the positions of the cut portion and the perforation-like score line are unlikely to shift with respect to each other. Therefore, the double portion of the frame can be formed with high precision.

The sheet body may be a plurality of sheet bodies, and in the sheet body arrangement step, each of the plurality of sheet bodies may be arranged so as to overlap one or more corresponding sides of each side of the electrode.

The folding process and the curling process may be performed as a series of operations while the position of the electrode is fixed. Since the folding process and the heating process are performed as a series of operations, it can contribute to reducing processing time.

In the cutting process, one mold is equipped with a blade for cutting the four corners of the extended portion and a blade for forming the perforation-like cut line. Line formation may also be performed.

In the folding process, the frame body is folded back along the perforation-like score line, so that the first part of the frame body inside the perforation-like score line is folded back on the outside of the perforation-like score line. The separator may extend inwardly from the folded second portion, and the method may include arranging the separator so as to overlap the first portion which extends inwardly from the folded second portion.

According to the manufacturing method according to one aspect of the present invention, an electrode unit in which a separator can be appropriately arranged between electrode plates can be provided.

FIG. 1 is a schematic cross-sectional view showing an example of a power storage device. FIG. 3 is a flow diagram showing a method for manufacturing an electrode unit. It is a figure for explaining the manufacturing method of an electrode unit. It is a figure for explaining the manufacturing method of an electrode unit. It is a figure for explaining the manufacturing method of an electrode unit. It is a figure for explaining the manufacturing method of an electrode unit. FIG. 3 is a diagram for explaining a perforation/cutting process. It is a figure for explaining the manufacturing method of an electrode unit. It is a top view for demonstrating a folding process and a curling process.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and redundant description will be omitted.

The power storage device 1 shown in FIG. 1 may be, for example, a power storage module used in batteries of various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 is, for example, a secondary battery such as a nickel-metal hydride secondary battery or a lithium ion secondary battery. Power storage device 1 may be an electric double layer capacitor. In the present embodiment, the power storage device 1 includes a positive electrode in which a positive electrode active material layer is formed on the surface of a conductive current collector, and a negative electrode in which a negative electrode active material layer is formed on the surface of the current collector. A bipolar type nickel-metal hydride secondary battery having a power generation element including an electrolyte layer in which an electrolyte is held in a separator placed between a positive electrode and a negative electrode, and having a plurality of stacked bipolar electrodes. The case of a battery will be exemplified.

As shown in FIG. 1, power storage device 1 includes an electrode stack 11 and a resin sealing body 12 that seals electrode stack 11. Power storage device 1 is formed, for example, in the shape of a rectangular parallelepiped. The electrode stack 11 includes a plurality of electrodes stacked with a separator 13 in between, and end current collectors 20A and 20B arranged at the stacked ends of the electrode stack 11 in the electrode stacking direction (Z direction). Contains. The plurality of electrodes includes a stack of bipolar electrodes 14, a negative terminal electrode 18, and a positive terminal electrode 19. A stack of bipolar electrodes 14 is provided between a negative terminal electrode 18 and a positive terminal electrode 19.

The bipolar electrode 14 is provided on a current collector 15 including one surface 15a facing upward in the Z direction in FIG. 1 and the other surface 15b facing downward in the Z direction in FIG. The current collector 15 has a positive electrode 16 and a negative electrode 17 provided on the other surface 15b of the current collector 15. The positive electrode 16 includes a current collector 15 and a positive electrode active material layer formed by coating the current collector 15 with a positive electrode active material. The negative electrode 17 includes a current collector 15 and a negative electrode active material layer formed by coating the current collector 15 with a negative electrode active material. In this embodiment, the current collector 15 serves as both the current collector for the positive electrode 16 and the current collector for the negative electrode 17. In the electrode stack 11, the positive electrode 16 of one bipolar electrode 14 faces the negative electrode 17 of another bipolar electrode 14 adjacent to it on one side in the Z direction with the separator 13 in between. In the electrode stack 11, the negative electrode 17 of one bipolar electrode 14 faces the positive electrode 16 of another bipolar electrode 14 adjacent to the other side in the Z direction with the separator 13 in between.

The negative terminal electrode 18 includes a current collector 15 and a negative electrode 17 provided on a surface 15b of the current collector 15 facing downward in the Z direction in FIG. The negative terminal electrode 18 is arranged at one end of the stack of bipolar electrodes 14 in the Z direction so that the surface 15b on which the negative active material layer is formed faces the center of the electrode stack 11 in the Z direction. . No active material layer is provided on the surface 15a of the current collector 15 of the negative terminal electrode 18 facing upward in the Z direction in FIG. 1, and an end current collector 20A is further laminated on this surface 15a. The negative terminal electrode 18 is electrically connected to an external terminal member or the like via this end current collector 20A. The negative electrode 17 provided on the surface 15b of the current collector 15 of the negative terminal electrode 18 faces the positive electrode 16 of the bipolar electrode 14 at one end in the Z direction with the separator 13 in between.

The positive terminal electrode 19 includes a current collector 15 and a positive electrode 16 provided on a surface 15a of the current collector 15 facing upward in the Z direction in FIG. The positive terminal electrode 19 is attached to one end of the stack of bipolar electrodes 14 in the Z direction (the negative terminal electrode 18 (at the end opposite to the side where the No active material layer is provided on the surface 15b of the current collector 15 of the positive terminal electrode 19 facing downward in the Z direction in FIG. 1, and an end current collector 20B is further laminated on this surface 15b. The positive terminal electrode 19 is electrically connected to an external terminal member or the like via this end current collector 20B. The positive electrode 16 provided on the surface 15a of the current collector 15 of the positive terminal electrode 19 faces the negative electrode 17 of the bipolar electrode 14 at the other end in the Z direction with the separator 13 in between.

The current collector 15 is not particularly limited as long as it has electronic conductivity and is not easily eluted into the electrolyte at the battery operating potential applied to the current collector, but for example, it may be made of nickel foil or nickel plated. A metal foil such as steel foil is used. When a rectangular metal foil is used as the current collector 15, a rectangular frame-shaped uncoated area where the positive electrode active material and the negative electrode active material are not coated is provided at the edge 15c. Examples of the positive electrode active material constituting the positive electrode 16 include nickel hydroxide. Examples of the negative electrode active material constituting the negative electrode 17 include a hydrogen storage alloy. In this embodiment, the formation region of the negative electrode active material layer formed on the surface 15b of the current collector 15 facing downward in the Z direction in FIG. 1 is formed on the surface 15a of the current collector 15 facing upward in the Z direction in FIG. It is one size larger than the formation area of the positive electrode active material layer to be formed.

The separator 13 is a member that has the function of preventing a short circuit between the positive electrode 16 and the negative electrode 17 that are arranged facing each other, and also has the function of retaining the electrolyte and ensuring ionic conductivity between the positive electrode 16 and the negative electrode 17. For example, it is formed into a sheet shape. Examples of the separator 13 include porous sheets and nonwoven fabric separators made of polymers or fibers that have electrical insulation properties and absorb and retain electrolytes. Specifically, porous films made of polyolefin resins such as polyethylene (PE) and polypropylene (PP), woven fabrics or nonwoven fabrics made of polypropylene, methyl cellulose, etc. are exemplified. Note that the separator 13 may be reinforced with a vinylidene fluoride resin compound.

The end current collectors 20A and 20B are substantially the same member as the current collector 15, and are made of metal foil such as nickel foil or nickel-plated steel foil. In the end current collectors 20A and 20B, both a positive electrode active material and a negative electrode active material are coated on one surface 20a facing upward in the Z direction in FIG. 1 and the other surface 20b facing downward in the Z direction in FIG. It is a current collector that has not been used.

The end current collector 20A is arranged at one stacked end of the electrode stack 11. The negative terminal electrode 18 is placed between the end current collector 20A and the bipolar electrode 14 along the Z direction. The end current collector 20B is arranged at the other stacked end of the electrode stack 11. The positive terminal electrode 19 is placed between the end current collector 20B and the bipolar electrode 14 along the Z direction.

The sealing body 12 is made of, for example, an insulating resin. The sealing body 12 is formed into a rectangular cylindrical shape as a whole so as to surround the side surface 11a of the rectangular parallelepiped electrode stack 11 formed by stacking rectangular electrodes. The sealing body 12 holds the edges 15c of each current collector 15 and the edges 20c of the end current collectors 20A and 20B on the side surface 11a of the electrode stack 11. The sealing body 12 is a frame joined to the edges of the current collectors included in the electrode stack 11 (that is, the edges 15c of the current collector 15 and the edges 20c of the end current collectors 20A and 20B). a first sealing part 21 (resin part) having a shape, and a second sealing part 21 that surrounds the first sealing part 21 from the outside along the side surface 11a of the electrode stack 11 and is coupled to each of the first sealing parts 21. It has a sealing part 22. In this embodiment, since the power storage device 1 is a nickel-metal hydride secondary battery, the first sealing part 21 and the second sealing part 22 are made of, for example, an insulating resin having alkali resistance. Examples of the constituent materials of the first sealing part 21 and the second sealing part 22 include polypropylene (PP), polyphenylene sulfide (PPS), modified polyphenylene ether (modified PPE), and the like.

The first sealing portion 21 is continuously provided over the entire circumference of the edge 15c of each current collector 15 and the edge 20c of each of the end current collectors 20A, 20B. It has a rectangular frame shape. The first sealing portion 21 is configured to collect current by, for example, ultrasonic welding, thermal welding, etc. so that the first sealing portion 21 and the current collector 15 or the end current collectors 20A, 20B are airtightly joined. It is welded to the edge 15c of the body 15 or the edge 20c of the end current collectors 20A, 20B. The first sealing portion 21 includes an outer portion 21a that extends outward from the edge of the current collector 15 or the end current collectors 20A, 20B, and an outer portion 21a that extends outward from the edge of the current collector 15 or the end current collectors 20A, 20B. and an inner portion 21b located inside. The tips (outer edges) of the outer portions 21a of the plurality of first sealing portions 21 arranged in the stacking direction of the electrodes form a welding layer 23 formed by bonding the outer portions of the first sealing portions 21 adjacent in the stacking direction. have. For forming the welding layer 23, a known welding method such as hot plate welding, ultrasonic welding, or infrared welding can be used. Note that the frame-shaped first sealing part 21 joined to the rectangular current collector foil may have the welding layer 23 formed on all the outer edges, or the welding layer 23 may be formed only on some of the outer edges. You can leave it there.

The plurality of first sealing parts 21 include a first sealing part 21A provided on the bipolar electrode 14 and the positive terminal electrode 19, a first sealing part 21B provided on the negative terminal electrode 18, and an end current collector. It has a first sealing part 21C provided on the body 20A and first sealing parts 21D and 21E provided on the end current collector 20B.

The first sealing portion 21A is joined to one surface 15a of the current collector 15 of the bipolar electrode 14 and the positive terminal electrode 19 facing upward in the Z direction in FIG. The inner portion 21b of the first sealing portion 21A is located between the edges 15c of a pair of current collectors 15 adjacent to each other in the Z direction. A region where the edge 15c on one surface 15a of the current collector 15 and the first sealing portion 21A overlap is a bonding region between the current collector 15 and the first sealing portion 21A.

In this embodiment, the first sealing portion 21A has a two-layer structure in which a single film bonded to the edge 15c of the current collector 15 is folded in two at the outer portion 21a. The outer edge portion of the first sealing portion 21A is provided in the outer portion 21a and includes a folded portion (bent portion) of the film. The folded portion of this film is joined to the second sealing portion 22. The first layer of film constituting the first sealing portion 21A is bonded to one surface 15a of the current collector 15. The first layer film includes an inner portion 21b joined to the current collector 15 and an outer portion 21a extending outward from the edge of the current collector 15. The inner edge of the second layer film is located outside the inner edge of the first layer film, thereby forming a stepped portion for placing the separator 13 on the first sealing portion 21A. Note that the inner edge of the second layer film is located inside the edge of the current collector 15. That is, the second layer film includes an inner portion 21 b that is inside the edge of the current collector 15 and an outer portion 21 a that extends outside the edge of the current collector 15 . As a result, the first sealing portion 21A having a two-layer structure has an inner portion 21b sandwiched between a pair of current collectors 15 adjacent to each other in the Z direction.

The first sealing portion 21B is joined to the surface 15a of the current collector 15 of the negative terminal electrode 18 facing upward in the Z direction in FIG. The inner portion 21b of the first sealing portion 21B is located between the edge 15c of the current collector 15 of the negative terminal electrode 18 adjacent to each other in the Z direction and the edge 20c of the end current collector 20A. There is. The area where the edge 15c on the surface 15a of the current collector 15 and the inner portion 21b of the first sealing part 21B overlap is a bonding area between the current collector 15 and the first sealing part 21B. The first sealing portion 21B is also joined to the edge 20c of the surface 20b of the end current collector 20A facing downward in the Z direction in FIG. The area where the edge 20c on the surface 20b of the end current collector 20A and the first sealing part 21B overlap is a joining area between the end current collector 20A and the first sealing part 21B.

The first sealing portion 21C is joined to the surface 20a of the end current collector 20A facing upward in the Z direction in FIG. In this embodiment, the first sealing part 21C is located at the end in the Z direction among the plurality of first sealing parts 21. The area where the edge 20c on the surface 20a of the end current collector 20A and the first sealing part 21C overlap is a joining area between the end current collector 20A and the first sealing part 21C.

In this embodiment, the outer edges of the first sealing parts 21B and 21C joined to the second sealing part 22 are continuous. That is, the first sealing portions 21B and 21C are formed by folding one film into two with the edge 20c of the end current collector 20A interposed therebetween. The outer edge portions of the first sealing portions 21B and 21C are folded portions (bent portions) of the film. The films constituting the first sealing parts 21B and 21C are joined to the edge 20c on both the surface 20a and the surface 20b of the end current collector 20A. In this way, the first sealing part 21B sandwiched between the current collector 15 and the end current collector 20A of the negative terminal electrode 18 is joined to each current collector, and further, the first sealing part 21B is By joining the first sealing portion 21C configured to be connected to the end current collector 20A, it is possible to suppress seepage of the electrolytic solution due to the so-called alkali creep phenomenon.

The first sealing portion 21D is joined to the surface 20a of the end current collector 20B facing upward in the Z direction in FIG. The inner portion 21b of the first sealing portion 21D is located between the edge 15c of the current collector 15 of the positive terminal electrode 19 adjacent to each other in the Z direction and the edge 20c of the end current collector 20B. There is. The area where the edge 20c on the surface 20a of the end current collector 20B and the first sealing part 21D overlap is a bonding area between the end current collector 20B and the first sealing part 21D. Further, in this embodiment, the first sealing portion 21D is not joined to the current collector 15.

The first sealing part 21E is joined to the edge 20c of the end current collector 20B on the surface 20b facing downward in the Z direction in FIG. In this embodiment, the first sealing part 21E is located at the end in the Z direction (the end opposite to the first sealing part 21C) among the plurality of first sealing parts 21. The area where the edge 20c on the surface 20b of the end current collector 20B and the first sealing part 21E overlap is a bonding area between the end current collector 20B and the first sealing part 21E.

In this embodiment, the outer edges of the first sealing parts 21D and 21E joined to the second sealing part 22 are continuous. That is, the first sealing parts 21D and 21E are formed by folding one film into two with the edge 20c of the end current collector 20B interposed therebetween. The outer edges of the first sealing parts 21D and 21E are folded parts (bent parts) of the film. The films constituting the first sealing parts 21D and 21E are joined to the edge 20c at the surface 20a and the surface 20b of the end current collector 20B.

The end current collector 20A located at the stacked end of the electrode stack 11 is sealed with a first sealing part 21 and a second sealing part 22 on a part of the surface 20a facing upward in the Z direction in FIG. It has an exposed surface 20d exposed from the body 12. The end current collector 20B located at the stacked end of the electrode stack 11 has a sealing member formed of a first sealing part 21 and a second sealing part 22 on a part of the surface 20b facing downward in the Z direction in FIG. It has an exposed surface 20d exposed from the stopper 12. An external terminal member, a conductive plate, etc. are arranged in contact with each exposed surface 20d, and the end current collectors 20A, 20B and the external terminal member etc. are electrically connected.

In the bonding region between the current collector and the first sealing portion, the surfaces of the current collector 15 and the end current collectors 20A and 20B are roughened. The roughened region may be only the bonding region, but in this embodiment, the entire surface 15a of the current collector 15 is roughened. Further, the entire surfaces 20a and 20b of the end current collector 20A are roughened. Further, the entire surfaces 20a and 20b of the end current collector 20B are roughened.

Roughening can be achieved by forming a plurality of microprotrusions on the surface of the current collector, for example, by electrolytic plating. By forming a plurality of microprotrusions in the bonding region, the molten resin becomes coarse at the bonding interface between the current collector and the first sealing portion 21 in the bonding region between the current collector and the first sealing portion. The resin enters between the plurality of microprotrusions formed by planarization, and remains solidified in that state. Thereby, a so-called anchor effect is exerted that suppresses the first sealing part from peeling off from the current collector. Therefore, the bonding strength between the current collector 15, the end current collectors 20A and 20B, and the first sealing portion 21 can be improved. A plurality of microprotrusions are formed on the surface of the current collector due to surface roughening, and at least some of the microprotrusions are, for example, protrusions having a constricted portion in a portion between the base end and the tip end. There is. In other words, the protrusion has an overhang portion in a portion thereof. The plurality of microprotrusions having the constricted portions make it possible to enhance the anchoring effect in joining the current collector and the first sealing portion.

The second sealing part 22 is provided outside the electrode stack 11 and the first sealing part 21 so as to surround the side surface 11a of the electrode stack 11, and constitutes an outer wall (housing) of the power storage device 1. . The second sealing portion 22 is formed, for example, by injection molding of resin, and its outer wall portion has a portion extending along the entire length of the electrode stack 11 along the Z direction. The second sealing portion 22 has a rectangular cylindrical shape extending in the Z direction as an axial direction. The second sealing part 22 is welded to the outer surface of the first sealing part 21, for example, by heat during injection molding.

The sealing body 12 forms an internal space V between adjacent electrodes and also seals the internal space V. More specifically, the second sealing part 22, together with the first sealing part 21, connects between the bipolar electrodes 14 adjacent to each other along the Z direction, and between the negative terminal electrodes 18 and the bipolar electrodes adjacent to each other along the Z direction. The positive terminal electrode 19 and the bipolar electrode 14, which are adjacent to each other along the Z direction, are sealed. As a result, airtightly partitioned internal spaces V are formed between adjacent bipolar electrodes 14, between the negative terminal electrode 18 and the bipolar electrode 14, and between the positive terminal electrode 19 and the bipolar electrode 14. ing. This internal space V accommodates an electrolytic solution (not shown) containing an alkaline solution such as an aqueous potassium hydroxide solution. The electrolytic solution is impregnated into the separator 13, the positive electrode 16, and the negative electrode 17. The sealing body 12 also seals between the end current collector 20A and the negative terminal electrode 18 and between the end current collector 20B and the positive terminal electrode 19, respectively.

Next, a method for manufacturing an electrode unit according to an example will be described. In this embodiment, when manufacturing the power storage device 1, the electrode unit 30 is manufactured in advance. The electrode unit 30 includes a bipolar electrode 14 and a first sealing part 21 joined to the edge 15c of the current collector 15 of the bipolar electrode 14. As shown in FIG. 2, the method for manufacturing such an electrode unit 30 includes an arrangement step (sheet arrangement step) S11, a joining step (frame joining step) S12, and a perforation/cutting step (cutting step) S13. , including a folding step S14 and a curling step S15. 3 and 4 are diagrams for explaining the arrangement process. FIG. 5 is a diagram for explaining the joining process. 6 and 7 are diagrams for explaining the perforation/cutting process. FIGS. 8 and 9 are diagrams for explaining the folding process and the curling process.

In the arrangement step S11, resin sheet bodies (films) constituting the first sealing part 21 are arranged along the edges of each side of the rectangular electrode so as to overlap each corresponding side. In this embodiment, as shown in FIG. 3, a rectangular bipolar electrode 14 and four sheet bodies 121 corresponding to each side of the bipolar electrode 14 are prepared. In one example, the four sheet bodies 121 include two sheet bodies 121L corresponding to the long sides of the bipolar electrode 14 and two sheet bodies 121S corresponding to the short sides. These four sheet bodies 121 are parts that become the first sealing part 21 in the electrode unit 30.

The sheet body 121L has a trapezoidal shape in plan view. That is, the sheet body 121L includes an upper base 121La and a lower base 121Lb that constitute the base of the trapezoid, and a pair of legs 121Lc that connect the upper base 121La and the lower base 121Lb. Note that in this specification, the longer side of the bases is referred to as the lower base 121Lb. In the illustrated example, the sheet body 121L has an isosceles trapezoidal shape in which the inner angle between the lower base 121Lb and the legs 121Lc is 45°. The length of the upper base 121La of the sheet body 121L is shorter than the length of the long side 14L of the bipolar electrode 14, and the length of the lower base 121Lb of the sheet body 121L is longer than the length of the long side 14L of the bipolar electrode 14.

The sheet body 121S has a trapezoidal shape in plan view. That is, the sheet body 121S includes an upper base 121Sa and a lower base 121Sb that constitute the base of a trapezoid, and a pair of legs 121Sc that connect the upper base 121Sa and the lower base 121Sb. In the illustrated example, the sheet body 121S has an isosceles trapezoid shape in which the inner angle between the lower base 121Sb and the legs 121Lc is 45°. The length of the upper base 121Sa of the sheet body 121S is shorter than the length of the short side 14S of the bipolar electrode 14, and the length of the lower base 121Sb of the sheet body 121S is longer than the length of the short side 14S of the bipolar electrode 14.

As shown in FIG. 4, in the arrangement step S11, four sheet bodies 121 are arranged so as to overlap each corresponding side. For example, the four sheet bodies 121 may be arranged on corresponding sides of the bipolar electrode 14. Note that the bipolar electrodes 14 may be arranged on the four sheet bodies 121 arranged at predetermined positions.

In FIG. 4, the legs 121Lc of the sheet body 121L and the legs 121Sc of the sheet body 121S are drawn in contact with each other when the sheet body 121 is disposed on the bipolar electrode 14. The portion including the leg 121Lc and the portion of the sheet body 121S including the leg 121Sc may overlap with each other. That is, the longitudinal ends of the sheet body 121L and the longitudinal ends of the sheet body 121S may overlap each other. Note that in FIG. 4, the positions of the legs of the sheet body 121 overlap with the positions of the apexes of the bipolar electrodes 14, but even if the positions of the legs of the sheet body 121 and the positions of the apexes of the bipolar electrodes 14 are shifted from each other, good.

In the joining step S12, the four sheet bodies 121 arranged in a frame shape are joined to the bipolar electrode 14. Examples of the method for joining the sheet body 121 and the bipolar electrode 14 include welding using ultrasonic waves or heat. When the first sealing part 21 is composed of a plurality of sheet bodies, the sheet bodies 121 are arranged so that the exposed parts of the current collectors 15 of the bipolar electrodes 14 are not formed at the joints between the ends of the sheet bodies 121 adjacent to each other. The ends of adjacent sheet bodies 121 are joined to each other in joining step S12. For example, when a portion including the legs of the sheet body 121L and a portion including the legs of the sheet body 121S are arranged so as to overlap each other, by heating the entire surface of the sheet body 121, the adjacent sheet bodies 121 is welded. In this case, the four sheet bodies 121 form a frame 124 having a substantially rectangular frame shape. That is, in the bonding step S12, a bipolar electrode 14 with a frame 124 having a substantially rectangular frame shape is formed.

In the perforation/cutting step S13, in the rectangular frame 124, four corners of the extending portion extending outward from the edge of the bipolar electrode 14 are cut to form a cut portion (cutting). At the same time, a perforated cut line 125 for folding is formed between adjacent cut portions of the frame 124 (perforation processing). The perforated cut line is formed by making small holes intermittently along the extending direction of the frame. Through this process, the frame body 124 is processed into a frame body 128. As shown in FIG. 6, the cut line 125 formed by the perforation/cutting process S13 is formed along a rectangular shape outside the periphery of the bipolar electrode 14. The score line 125 has a cutting portion 125a and a connecting portion 125b. The cut portion 125a is a portion where the frame 128 is completely cut in the thickness direction. The connecting portion 125b is a portion in which a portion outside the cut line 125 and an inner portion surrounded by the cut line 125 are continuous.

Further, as shown in FIG. 6, the portion (separated portion 126) cut by the perforation/cutting process in one example has a triangular shape including each vertex of the frame 124 having a rectangular frame shape. In one example, the separation portion 126 has an isosceles triangular shape. In the illustrated example, the apex 125P of the rectangle formed by the cut line 125 is located on the cutting line 126L (cutting portion) along which the separation portion 126 is cut. Note that the apex 125P of the cut line 125 may be included in the separation portion 126, but in that case, the cut line 125 does not need to be formed in the separation portion 126. By cutting the four corners of the frame 124, the frame 128 has a rectangular frame-shaped first portion 128a inside the cut line 125 and four trapezoidal second portions outside the cut line 125. 128b is formed. In the width direction intersecting the direction of the corresponding side, the length L1 of the second portion 128b is shorter than the length L2 of the first portion 128a, and longer than the distance L3 from the cut line 125 to the bipolar electrode 14.

In one example, the perforation and cutting in the perforation/cutting step S13 are performed simultaneously with the bipolar electrode 14 positioned. For example, as shown in FIG. 7, a press machine 200 may be used in this step. An example of a press machine 200 includes a press section 210 provided with one Thomson die 211 and a pedestal 230 on which a jig 220 is fixed. The press section 210 is provided so as to be movable up and down. The Thomson die 211 has a Thomson blade that performs perforation and a Thomson blade that performs cutting. The jig 220 clamps the bipolar electrode 14 to which the frame 124 is joined in the thickness direction. The bipolar electrode 14 is positioned by fixing the jig 220 holding the bipolar electrode 14 to the pedestal 230. By lowering the press section 210 in a state where the bipolar electrode 14 to which the frame body 124 is joined is positioned, perforation and cutting are performed simultaneously.

In the folding step S14, as shown in FIG. Fold back the second portion 128b. Thereby, the second portion 128b is overlapped with the first portion 128a of the frame 128, forming a folded portion. The four second portions 128b overlaid on the first portion 128a may form a substantially rectangular frame shape. The inner circumferential side of the first portion 128a extends further inside than the inner circumference of the folded second portion 128b.

In the shaping step S15, the folded portion of the frame 128 is shaped so that the folded state is maintained. In an example of the shaping step S15, the folded frame body 128 is heated while being pressed in the thickness direction (stacking direction). In this step, it is sufficient that the folded state is maintained for a period of time until the plurality of manufactured electrode units 30 are stacked on each other. Therefore, it is not necessary to heat the first portion 128a and the second portion 128b to such a high temperature that they are welded together.

In one example, the folding step S14 and the curling step S15 are performed as a series of operations while the position of the bipolar electrode 14 is fixed. In this step, for example, as shown in FIG. 9, a heating device 300 may be used. An example heating device 300 includes a fixed part 310 and a movable part 320. The fixing part 310 may be a plate having a flat upper surface 311, for example. The movable part 320 is movable, for example, up and down, has a heating part such as a heater inside, and has a flat bottom surface that is heated by the heating part. In the example heating device 300, the frame 128 is inserted between the fixed part 310 and the movable part 320 while being folded along the score line 125, with the movable part 320 waiting at a predetermined height position. Then, a region of the folded frame body 128 including the cut line 125 is held between the fixed part 310 and the movable part 320. The movable part 320 is heated by the heating part while holding the frame 128, thereby completing the curling of the frame 128. The electrode unit 30 is manufactured through each of the above steps.

In the method for manufacturing the electrode unit 30 described above, the frame body 124 is formed by the sheet bodies 121 arranged on each side of the bipolar electrode 14. When the frame 124 is processed into a frame 128, four corners are cut and score lines 125 are formed. By folding back the frame 128 along the cut line 125, the frame 128 is partially formed double by the first portion 128a and the second portion 128b. Since the cut line 125 is formed between the cut lines 126L, the double portion of the frame 128 can form a rectangular shape. By pressing and heating the folded frame 128, the frame 128 is bent in the folded state. As a result, a first sealing portion is formed by the frame 128. The separator 13 can be appropriately arranged in the inner space of the second portion 128b folded back into a rectangular frame shape so as to overlap the first portion 128a extending inward from the inner periphery of the second portion 128b. In this method, since the formation of the cutting line 126L and the formation of the scoring line 125 are performed simultaneously in the same process, the positions of the cutting line 126L and the scoring line 125 are unlikely to shift relative to each other. Therefore, the double portion of the frame 128 can be formed with high precision.

Further, in one example, the folding step and the curling step are performed as a series of operations with the position of the bipolar electrode 14 being fixed. Since the folding process and the curling process are performed in a series of operations, it can contribute to reducing machining time. Further, since the folding is performed while the folded state is maintained, the first portion 128a and the second portion 128b are prevented from shifting from each other.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

For example, in the curling step, the first portion 128a and the folded second portion 128b may be welded to each other. For example, in a portion where the first portion 128a, the second portion 128b, and the bipolar electrode 14 overlap each other, the first portion 128a and the second portion 128b may be partially welded to each other by spot welding or the like.

Further, in the arrangement step, a configuration in which four sheet bodies are arranged on each of the four sides of a rectangular electrode has been described, but the present invention is not limited to this. In the arrangement step, the sheet body may be arranged along the periphery of the electrode so as to overlap the periphery. For example, in the arrangement step, each of the plurality of sheet bodies may be arranged so as to overlap one or more corresponding sides of each side of the electrode. As an example, two L-shaped sheet bodies corresponding to the long sides and short sides of the electrode may be prepared, and these two sheet bodies may be arranged in a frame shape so as to overlap the corresponding sides. Alternatively, a frame-shaped sheet body may be prepared along the periphery of the electrode, and this sheet body may be arranged so as to overlap the periphery of the electrode.

Further, in the above embodiment, the electrode unit 30 including the bipolar electrode 14 and the first sealing part 21 (frame body 128) joined to the edge 15c of the bipolar electrode 14 has been described. It may be configured to include a separator 13. In this case, the electrode unit is manufactured by passing through the process of arranging the separator 13 in the inner space of the second portion 128b folded back into a rectangular frame shape after the forming process.

DESCRIPTION OF SYMBOLS 14... Bipolar electrode (electrode), 30... Electrode unit, 121... Sheet body, 124, 128... Frame body, 125... Cut line, 126L... Cutting line (cutting part).

Claims (5)

A method for manufacturing an electrode unit, comprising:
a sheet body arrangement step of arranging a resin sheet body along the edge of each side of the rectangular electrode so as to overlap each corresponding side;
a frame joining step of joining the arranged sheet body to the electrode to form an electrode with a substantially rectangular frame constituted by the sheet body;
In the rectangular frame, four corners of the extending portion extending outward from the edge of the electrode are cut to form cut portions, and at the same time, there are discontinuities between adjacent cut portions of the frame. A cutting process of forming a perforation-like cut line for folding by drilling a small hole,
a folding step of folding a portion of the extending portion on each side of the rectangular frame-like frame body outside the perforation-like cut line inward along the perforation-like cut line; a forming step of heating the folded portion of the frame while pressing it in the thickness direction;
After the forming step, a step of arranging a separator so as to overlap the frame ,
The sheet body is a plurality of sheet bodies,
The sheet body arrangement step is a method for manufacturing an electrode unit, in which each of the plurality of sheet bodies is arranged so as to overlap one or more corresponding sides of each side of the electrode. A method for manufacturing an electrode unit, comprising:
a sheet body arrangement step of arranging a resin sheet body along the edge of each side of the rectangular electrode so as to overlap each corresponding side;
a frame joining step of joining the arranged sheet body to the electrode to form an electrode with a substantially rectangular frame constituted by the sheet body;
In the rectangular frame, four corners of the extending portion extending outward from the edge of the electrode are cut to form cut portions, and at the same time, there are discontinuities between adjacent cut portions of the frame. A cutting process of forming a perforation-like cut line for folding by drilling a small hole,
a folding step of folding a portion of the extending portion on each side of the rectangular frame-like frame body outside the perforation-like cut line inward along the perforation-like cut line; a forming step of heating the folded portion of the frame while pressing it in the thickness direction;
After the forming step, a step of arranging a separator so as to overlap the frame ,
The method for manufacturing an electrode unit , wherein the folding step and the curling step are performed as a series of operations while the position of the electrode is fixed . 2. The method for manufacturing an electrode unit according to claim 1 , wherein the folding step and the curling step are performed as a series of operations while the position of the electrode is fixed. In the cutting step, one die is provided with a blade for cutting the four corners of the extending portion and a blade for forming the perforation-like cut line. The method for manufacturing an electrode unit according to any one of claims 1 to 3, wherein a perforation-like score line is formed. In the folding step, the frame body is folded back along the perforation-like score line, so that a first portion of the frame body inside the perforation-like score line is aligned with the perforation-like score line. Extending inward from the folded second part on the outside,
According to any one of claims 1 to 4, the step of arranging the separator is arranging the separator so as to overlap the first part extending inwardly than the folded second part. Method of manufacturing an electrode unit.

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