JP2021022534A - Power storage module and manufacturing method of power storage module - Google Patents

Abstract

To provide a power storage module capable of exhibiting good sealability, and to provide a manufacturing method of the power storage module.SOLUTION: A power storage module is equipped with an electrode laminate where multiple electrodes are laminated in a first direction via separators, and a seal member surrounding the electrode laminate. The seal member has a primary seal provided in the peripheral part of a collector, and a secondary seal covering the primary seal. The secondary seal has a first resin part covering a first outer side face formed by laminating the end faces of the primary seal in the first direction, and a second resin part covering a second outer side face of the first resin part. The first resin part has a first body part extending in the first direction and covering the first outer side face, a first eaves extending from one end of the first body part in the first direction toward the center of the electrode laminate in the surface direction intersecting the first direction, and a second eaves extending from the other end of the first body part in the first direction toward the center in the surface direction.SELECTED DRAWING: Figure 2

Description

The present invention relates to a power storage module and a method for manufacturing the power storage module.

As a conventional power storage module, a bipolar battery including a bipolar electrode having a positive electrode formed on one surface of an electrode plate and a negative electrode formed on the other surface is known (see, for example, Patent Document 1 below). The bipolar battery includes a laminate in which bipolar electrodes and separators are alternately laminated along the stacking direction. On the side surface of the laminated body, a sealant (seal member) for sealing between the bipolar electrodes adjacent to each other in the stacking direction is provided, and the electrolytic solution is housed in the internal space formed between the bipolar electrodes. ..

Japanese Unexamined Patent Publication No. 2011-204386

The power storage module as described above may be mounted as a battery of a vehicle or the like, for example. In this case, it is desired to improve the sealing property of the power storage module from the viewpoint of preventing leakage of the electrolytic solution due to vibration or the like.

An object of the present invention is to provide a power storage module and a method for manufacturing a power storage module capable of exhibiting good sealing properties.

The power storage module according to one aspect of the present invention includes a plurality of electrodes including a current collector, a positive electrode provided on one surface of the current collector, and a bipolar electrode having a negative electrode provided on the other surface of the current collector. It includes an electrode laminate formed by being laminated along a first direction via a separator, and a seal member surrounding the electrode laminate. The seal member includes a primary seal provided on the peripheral edge of the current collector and a secondary seal that covers the primary seal. The secondary seal has end faces of the primary seal laminated along the first direction. It has a first resin portion that covers the first outer surface and a second resin portion that covers the second outer surface of the first resin portion, and the first resin portion extends in the first direction and is the first. A first main body covering the outer side surface, a first eaves extending from one end of the first main body in the first direction toward the center of the electrode laminate in a plane direction intersecting the first direction, and a first direction. The second body portion extends from the other end of the first main body portion toward the center of the electrode laminate in the plane direction.

In this power storage module, the seal member surrounding the electrode laminate has a primary seal and a secondary seal. By forming the sealing member with a plurality of members in this way, the sealing property of the power storage module can be improved. Further, the secondary seal includes a first main body portion that covers the first outer surface formed by laminating the end faces of the primary seal along the first direction, and a first main body portion located at both ends of the first main body portion in the first direction. It has a first resin part including an eaves part and a second eaves part. Therefore, the primary seal is fixed so as to be gripped by the first main body portion, the first eaves portion, and the second eaves portion of the first resin portion. As a result, when the second resin portion covering the second outer surface of the first resin portion is formed, the electrode (specifically, the current collector included in the electrode or the primary provided on the peripheral edge of the current collector) is provided. It is possible to prevent the seal) from rolling up. Therefore, the power storage module can exhibit good sealing performance.

The second resin portion extends in the first direction and covers the second outer surface of the first resin portion, and the center of the electrode laminate in the plane direction from one end of the second main body portion in the first direction. Along with extending toward the center of the electrode laminate in the plane direction from the other end of the second main body portion in the first direction and the third eaves portion covering the first eaves portion, the second eaves portion extends toward the center of the electrode laminate. It may have a fourth eaves portion that covers the eaves portions. For example, when a part of the electrodes is rolled up when the first resin part is formed, the part of the electrodes may be located outside the first eaves part or the second eaves part of the first resin part. Even in this case, the sealing property of the power storage module can be ensured by fixing some of the electrodes by the third eaves portion or the fourth eaves portion of the second resin portion.

The secondary seal further has a third resin portion that covers the third outer surface of the second resin portion, and the first resin portion may be covered with the second resin portion and the third resin portion. In this case, the power storage module can be satisfactorily sealed by covering the first resin portion with the second resin portion and the third resin portion.

The power storage module according to another aspect of the present invention has a first step of preparing a plurality of electrodes having bipolar electrodes and a second step of coupling a primary seal to the peripheral edge of a current collector of each of the plurality of electrodes. In the third step of forming an electrode laminate by laminating a plurality of electrodes in the first direction, and by temporarily joining the end faces of the primary seals laminated along the first direction, from the end faces to each other. A fourth step of forming the first outer surface thereof and a fifth step of forming a secondary seal covering the temporarily joined end faces are provided. In the fifth step, the first main body portion extending in the first direction and covering the first outer surface, from one end of the first main body portion in the first direction to the center of the electrode laminate in the surface direction intersecting the first direction. The first eaves extending toward the center and the second eaves extending toward the center of the electrode laminate in the plane direction from the other end located on the side opposite to one end of the first main body in the first direction. It has a sixth step of forming the first resin portion to have, and a seventh step of forming a second resin portion covering the second outer surface of the first resin portion.

In this method of manufacturing the power storage module, a primary seal and a secondary seal are formed. By sealing the electrode laminate with a plurality of members in this way, the sealing property of the power storage module can be improved. Further, the fifth step of forming the secondary seal is located at both ends of the first main body portion that covers the first outer surface composed of the end faces of the temporarily joined primary seals and the first main body portion in the first direction. It has a sixth step of forming a first resin portion including a first eaves portion and a second eaves portion. As a result, the primary seal is fixed so as to be gripped by the first main body portion, the first eaves portion, and the second eaves portion of the first resin portion. Therefore, when the second resin portion is formed in the seventh step, the electrode (specifically, the current collector included in the electrode or the primary seal provided on the peripheral portion of the current collector) is rolled up. Can be prevented. Therefore, the power storage module manufactured by the above manufacturing method can exhibit good sealing performance.

In the seventh step, the second main body portion extending in the first direction and covering the second outer surface of the first resin portion, and the center of the electrode laminate in the plane direction from one end of the second main body portion in the first direction. Along with extending toward the center of the electrode laminate in the plane direction from the other end of the second main body portion in the first direction and the third eaves portion covering the first eaves portion, the second eaves portion extends toward the center of the electrode laminate. A fourth eaves portion that covers the eaves portion may be formed. For example, some electrodes may be rolled up during the process of forming the first resin portion, so that some of the electrodes may be located outside the first eaves portion or the second eaves portion of the first resin portion. .. Even in this case, the sealing property of the power storage module can be ensured by fixing some of the electrodes by the third eaves portion or the fourth eaves portion of the second resin portion.

The fifth step further includes an eighth step of forming a third resin portion that covers the third outer surface of the second resin portion, and the first resin portion is covered with the second resin portion and the third resin portion. You may. In this case, the power storage module can be satisfactorily sealed by covering the first resin portion with the second resin portion and the third resin portion.

According to one aspect of the present invention, it is possible to provide a power storage module and a method for manufacturing a power storage module that can exhibit good sealing properties.

FIG. 1 is a schematic cross-sectional view of a power storage device including a power storage module. FIG. 2 is a schematic cross-sectional view showing the internal configuration of the power storage module shown in FIG. FIG. 3 is a flowchart for explaining a method of manufacturing a power storage module. FIG. 4 is a schematic enlarged view for explaining a process of forming the secondary seal. FIG. 5 is a schematic enlarged view for explaining a process of forming the secondary seal. FIG. 6A is a schematic cross-sectional view of a main part for explaining a process of forming a secondary seal according to a first comparative example, and each of FIGS. 6B and 6C is a first comparative example. It is a schematic main part sectional view which shows the state after formation of the secondary seal which concerns on. FIG. 7A is a schematic cross-sectional view of a main part for explaining a step of forming the first resin portion according to the second comparative example, and FIG. 7B is a schematic cross-sectional view of the first resin according to the second comparative example. It is a schematic cross-sectional view of a main part which shows the state after formation of a part.

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 duplicate description is omitted.

First, with reference to FIG. 1, a configuration of a power storage device including a power storage module manufactured by the method for manufacturing a power storage module according to the present embodiment will be described. FIG. 1 is a schematic cross-sectional view of a power storage device including a power storage module. The power storage device 1 shown in FIG. 1 is used as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 includes a module stack 2 including a plurality of stacked power storage modules 4, and a restraint member 3 that applies a restraint load to the module stack 2. In the following, the direction in which the power storage modules 4 are stacked is simply referred to as “stacking direction D (first direction)”. Further, the direction intersecting or orthogonal to the stacking direction D is defined as the plane direction. The plane direction has, for example, an X-axis direction and a Y-axis direction orthogonal to each other. In the present embodiment, "viewed from the stacking direction D" corresponds to a plan view.

The module laminate 2 includes a plurality of (three in this embodiment) power storage modules 4 and a plurality of (four in this embodiment) conductive structures 5. The power storage module 4 is, for example, a bipolar battery, and has a substantially rectangular shape when viewed from the stacking direction D. The power storage module 4 is, for example, a nickel hydrogen secondary battery, a secondary battery such as a lithium ion secondary battery, an electric double layer capacitor, or the like. In the following description, a nickel-metal hydride secondary battery will be illustrated as the power storage module 4.

The power storage modules 4 adjacent to each other in the stacking direction D are electrically connected to each other via the conductive structure 5. That is, a conductive structure 5 is provided between the adjacent power storage modules 4. In FIG. 1, the conductive structure 5 is also arranged outside the power storage module 4 located at both ends in the stacking direction D, but the present invention is not limited to this. The negative electrode terminal 6 is connected to the conductive structure 5 or the power storage module 4 located at one end (upper end in this embodiment) of the stacking direction D. The positive electrode terminal 7 is connected to the conductive structure 5 or the power storage module 4 located at the other end (lower end in this embodiment) of the stacking direction D. Each of the negative electrode terminal 6 and the positive electrode terminal 7 extends in the plane direction, for example. By providing such a negative electrode terminal 6 and a positive electrode terminal 7, charging / discharging of the power storage device 1 can be performed.

The conductive structure 5 can also function as a heat radiating plate in the power storage device 1. The conductive structure 5 can release the heat generated in the power storage module 4, for example. Inside the conductive structure 5, a plurality of flow paths 5a through which a refrigerant such as air flows are provided. The flow path 5a extends, for example, along the direction D3. By passing a refrigerant such as air through these flow paths 5a, the heat generated by the power storage module 4 can be efficiently released to the outside. In the example of FIG. 1, the area of the conductive structure 5 is smaller than the area of the power storage module 4 in a plan view. However, from the viewpoint of improving heat dissipation, the area of the conductive structure 5 may be the same as the area of the power storage module 4 or larger than the area of the power storage module 4 in a plan view.

The restraint member 3 is a member that restrains the power storage module 4 in the stacking direction D, and includes a pair of end plates 8 that sandwich the module laminate 2 in the stacking direction D, and fastening bolts 9 and nuts 10 that fasten the end plates 8 to each other. Have. Therefore, the binding force of the restraining member 3 is applied to the module laminated body 2 via the conductive structure 5. The end plate 8 is a metal plate having an area one size larger than the area of the power storage module 4 and the conductive structure 5 as viewed from the stacking direction D, and has a substantially rectangular shape. A film F having electrical insulation is provided on the surface of the end plate 8 on the module laminate 2 side. The film F insulates between the end plate 8 and the conductive structure 5 (or between the end plate 8 and the power storage module 4).

An insertion hole 8a is provided at the edge of the end plate 8 at a position outside the module laminate 2. The fastening bolt 9 is passed from the insertion hole 8a of one end plate 8 toward the insertion hole 8a of the other end plate 8, and is attached to the tip portion of the fastening bolt 9 protruding from the insertion hole 8a of the other end plate 8. , The nut 10 is screwed. As a result, the power storage module 4 and the conductive structure 5 are sandwiched by the end plate 8 and unitized as the module laminate 2. Further, a binding force is applied to the unitized module laminate 2 along the stacking direction D.

Next, the configuration of the power storage module 4 will be described in more detail. FIG. 2 is a schematic cross-sectional view showing the internal configuration of the power storage module shown in FIG. As shown in the figure, the power storage module 4 includes an electrode laminate 11 including a plurality of electrodes E laminated in the stacking direction D, and a seal member 12 surrounding the electrode laminate 11 when viewed from the stacking direction D. There is. The electrode laminate 11 and the sealing member 12 are sealed.

The electrode laminate 11 includes a plurality of electrodes E laminated in the stacking direction D via the separator 13. The plurality of electrodes E include a bipolar electrode 14, a negative electrode termination electrode 18, and a positive electrode termination electrode 19. The bipolar electrode 14 is included in the current collector 15, the positive electrode 16 provided on one surface 15a of the current collector 15, and the other surface 15b located on the opposite side of the one surface 15a in the stacking direction D. The provided negative electrode 17 is included. The positive electrode 16 is a positive electrode active material layer formed by applying a positive electrode active material on one surface 15a. The negative electrode 17 is a negative electrode active material layer formed by coating the negative electrode active material on the other surface 15b. In the electrode laminate 11, the positive electrode 16 of one bipolar electrode 14 faces the negative electrode 17 of one of the bipolar electrodes 14 adjacent to each other in the stacking direction D with the separator 13 interposed therebetween. In the electrode laminate 11, the negative electrode 17 of one bipolar electrode 14 faces the positive electrode 16 of the other bipolar electrode 14 adjacent to each other in the stacking direction D with the separator 13 interposed therebetween.

In the electrode laminate 11, the negative electrode terminal electrode 18 is arranged at one end in the stacking direction D, and the positive electrode terminal 19 is arranged at the other end in the stacking direction D. The negative electrode terminal electrode 18 includes a current collector 15 and a negative electrode 17 provided on the other surface 15b of the current collector 15. The negative electrode 17 of the negative electrode terminal electrode 18 faces the positive electrode 16 of the bipolar electrode 14 at one end in the stacking direction D via the separator 13. One conductive structure 5 adjacent to the power storage module 4 is in contact with one surface 15a of the current collector 15 of the negative electrode terminal electrode 18. The positive electrode terminal electrode 19 includes a current collector 15 and a positive electrode 16 provided on one surface 15a of the current collector 15. The other conductive structure 5 adjacent to the power storage module 4 is in contact with the other surface 15b of the current collector 15 of the positive electrode terminal electrode 19. The positive electrode 16 of the positive electrode terminal electrode 19 faces the negative electrode 17 of the bipolar electrode 14 at the other end in the stacking direction D via the separator 13.

The current collector 15 is a conductor having a plate shape extending in the plane direction and exhibits flexibility. The current collector 15 is, for example, a nickel foil, a plated steel plate, or a plated stainless steel plate. Examples of the steel sheet include cold-rolled steel sheets (SPCC and the like) specified in JIS G 3141: 2005. Examples of the stainless steel sheet include SUS304 and SUS316 specified in JIS G 4305: 2015. The peripheral edge portion 15c of the current collector 15 (peripheral portion of the bipolar electrode 14) has a rectangular frame shape, and is an uncoated region in which the positive electrode active material and the negative electrode active material are not coated. Examples of the positive electrode active material constituting the positive electrode 16 include nickel hydroxide. Nickel hydroxide may be coated with cobalt oxide or the like. Examples of the negative electrode active material constituting the negative electrode 17 include a hydrogen storage alloy. In the present embodiment, the formation region of the negative electrode 17 on the other surface 15b of the current collector 15 is slightly larger than the formation region of the positive electrode 16 on the one surface 15a of the current collector 15.

The separator 13 is a member for separating the positive electrode 16 and the negative electrode 17, and is arranged between the positive electrode 16 and the negative electrode 17. The separator 13 has, for example, a sheet shape. The separator 13 is a porous film made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP). The separator 13 may be a woven fabric or a non-woven fabric made of polypropylene, methyl cellulose or the like. The separator 13 may be reinforced with a vinylidene fluoride resin compound. The separator 13 is not limited to a sheet shape, but may be a bag shape.

The seal member 12 is a resin member configured to surround the electrode laminate 11. The seal member 12 is provided so as to surround the peripheral edge portion 15c of the current collector 15. The seal member 12 is formed in a rectangular frame shape by, for example, an insulating resin. Examples of the resin constituting the seal member 12 include polypropylene (PP), polyphenylene sulfide (PPS), modified polyphenylene ether (modified PPE), and the like. The seal member 12 includes a primary seal 21 provided on the peripheral edge portion 15c and a secondary seal 22 that covers the primary seal 21.

The primary seal 21 is a resin member bonded to each electrode and has a predetermined thickness (length in the stacking direction D). The primary seal 21 has a rectangular frame shape when viewed from the stacking direction D. The primary seal 21 is continuously welded over the entire circumference of the peripheral edge portion 15c by, for example, ultrasonic waves or heat. The primary seal 21 is provided, for example, on the peripheral edge portion 15c on the other surface 15b side of the current collector 15. The primary seal 21 is provided on the peripheral edge portion 15c on the one side 15a side of the current collector 15 included in the negative electrode terminal electrode 18. The primary seal 21 is provided on both the peripheral edge portion 15c on the one side 15a side and the peripheral edge portion 15c on the other side surface 15b side of the current collector 15 included in the positive electrode terminal electrode 19. The primary seal 21 is provided apart from the positive electrode 16 and the negative electrode 17 when viewed from the stacking direction D. The peripheral edges 21a of the primary seals 21 adjacent to each other in the stacking direction D may come into contact with each other. The primary seal 21 may be formed by punching a resin sheet, may be formed by arranging a plurality of resin sheets in a frame shape, or may be formed by injection molding using a mold. Good.

The peripheral edge portion 21a of the primary seal 21 in a plan view is at least a part of a region located outside the current collector 15 in the plane direction, and has an end face 21b located on the outermost side in the plane direction. At least a part of the peripheral edge portion 21a is held by the secondary seal 22. The primary seals 21 adjacent to each other along the stacking direction D may be separated from each other or may be in contact with each other. When the adjacent primary seals 21 are in contact with each other, the peripheral edges 21a of the primary seals 21 may be welded to each other. In the present embodiment, the peripheral edges 21a of all the primary seals 21 to be laminated are welded to each other, and therefore, the outer surface 21s (first) in which the end faces 21b of the primary seals 21 are laminated along the stacking direction D. The outer surface) is formed. Further, by welding the peripheral edges 21a to each other, an end face welding layer having a substantially rectangular frame shape in a plan view and extending along the stacking direction D is formed. The outer side surface 21s is an outer peripheral surface extending along the stacking direction D, and is a part of the end surface welding layer.

The secondary seal 22 is a resin member constituting the outer wall (housing) of the power storage module 4, and is provided outside the electrode laminate 11 and the primary seal 21. The secondary seal 22 is formed by injection molding of a resin, as will be described later, and extends over the entire length of the electrode laminate 11 in the lamination direction D. The secondary seal 22 is a rectangular tubular member extending with the stacking direction D as the axial direction. The secondary seal 22 is joined to the outer surface 21s of the primary seal 21 and covers the outer surface 21s. In the present embodiment, the secondary seal 22 completely covers the outer surface 21s of the primary seal 21 extending in the stacking direction D. The secondary seal 22 is welded to the outer surface 21s of the primary seal 21 by, for example, heat during injection molding. The resin constituting the primary seal 21 and the resin constituting the secondary seal 22 are compatible with each other. The primary seal 21 is made of, for example, PP, and the secondary seal 22 is made of, for example, modified PPE.

The secondary seal 22 has a first resin portion 23 covering an outer surface 21s composed of primary seals 21 laminated along the stacking direction D, and an outer surface 23s (second outer surface) of the first resin portion 23. A second resin portion 24 that surrounds the resin portion 24 is provided. The first resin portion 23 is a portion for temporarily fixing the electrode laminate 11 to which the primary seal 21 is bonded, and has a rectangular tubular shape, for example. Therefore, the first resin portion 23 has a rectangular frame shape in a plan view. The first resin portion 23 is arranged between the primary seal 21 and the second resin portion 24. The second resin portion 24 is a portion that serves as an outer wall of the power storage module, and has, for example, a rectangular cylinder shape. Therefore, the second resin portion 24 also exhibits a rectangular frame shape in a plan view. The resin constituting the first resin portion 23 and the resin constituting the second resin portion 24 are the same as each other, and are, for example, modified PPE.

The first resin portion 23 extends from one end of the main body portion 23a (first main body portion) extending in the stacking direction D and the main body portion 23a in the stacking direction D toward the center of the electrode laminated body 11 in the plane direction. It has an eaves portion 23b (first eaves portion) and an eaves portion 23c (second eaves portion) extending from the other end of the main body portion 23a in the stacking direction D toward the center of the electrode laminated body 11 in the plane direction. The main body portion 23a is a portion that covers the outer surface 21s formed of the primary seal 21 and seals between adjacent primary seals 21. One end of the main body 23a corresponds to the end on the positive electrode 19 side in the stacking direction D, and the other end of the main body 23a corresponds to the end on the negative electrode 18 side in the stacking direction D. Each of one end of the main body 23a and the other end located on the opposite side of the one end are located outside the primary seal 21 in the stacking direction D.

The eaves portion 23b is a portion that covers the peripheral edge portion 21a of the primary seal 21 that is coupled to the negative electrode terminal electrode 18, for example, and exhibits a substantially rectangular frame shape in a plan view. The eaves portion 23b extends along the plane direction. The eaves portion 23c is a portion that covers the peripheral edge portion 21a of the primary seal 21 that is coupled to the positive electrode terminal electrode 19, for example, and exhibits a substantially rectangular frame shape in a plan view. The eaves portion 23c extends along the plane direction. In the present embodiment, each of the eaves 23b and 23c does not overlap the positive electrode 16 and the negative electrode 17 (more specifically, the positive electrode active material coating region and the negative electrode active material coating region) in a plan view. However, it is not limited to this. Each of the eaves 23b and 23c may or may not overlap with the current collector 15 in a plan view.

The second resin portion 24 extends from one end of the main body portion 24a (second main body portion) extending in the stacking direction D and the main body portion 24a in the stacking direction D toward the center of the electrode laminated body 11 in the plane direction. It has an eaves portion 24b (third eaves portion) and an eaves portion 24c (fourth eaves portion) extending from the other end of the main body portion 24a in the stacking direction D toward the center of the electrode laminated body 11 in the plane direction. The main body portion 24a is a portion that covers the outer surface 23s of the first resin portion 23. One end of the main body 24a corresponds to the end on the positive electrode 19 side in the stacking direction D, and the other end of the main body 24a corresponds to the end on the negative electrode 18 side in the stacking direction D. Each of one end of the main body portion 24a and the other end located on the opposite side of the one end are located outside the first resin portion 23 in the stacking direction D.

The eaves portion 24b is a portion that covers the eaves portion 23b and exhibits a substantially rectangular frame shape in a plan view. The eaves portion 24b extends along the plane direction. The eaves portion 24c is a portion that covers the eaves portion 23c and exhibits a substantially rectangular frame shape extending in the surface direction. The eaves portion 24c extends along the plane direction. In the present embodiment, each of the eaves 24b and 24c also overlaps the positive electrode 16 and the negative electrode 17 (more specifically, the positive electrode active material coating region and the negative electrode active material coating region) in a plan view. No, but not limited to this. Each of the eaves 24b and 24c may or may not overlap the current collector 15 in a plan view.

A plurality of internal spaces V are provided in the electrode laminate 11. Each internal space V is provided between adjacent electrodes E. The internal space V is a space airtightly and watertightly partitioned by the current collector 15 and the seal member 12 between the current collectors 15 adjacent to each other in the stacking direction D. For example, an electrolytic solution (not shown) is housed in this internal space V. The electrolytic solution is, for example, an aqueous electrolytic solution (specific example, a potassium hydroxide aqueous solution, a lithium hydroxide aqueous solution, or a mixed solution thereof). The separator 13, the positive electrode 16 and the negative electrode 17 are impregnated. Since the electrolytic solution is strongly alkaline, the sealing member 12 is made of a resin material exhibiting alkali resistance. The seal member 12 is provided with a communication hole that connects the internal space V and the outside of the power storage module 4.

Subsequently, an example of the above-mentioned manufacturing method of the power storage module 4 will be described with reference to FIGS. 3 to 5. FIG. 3 is a flowchart for explaining a method of manufacturing a power storage module. 4 and 5 are schematic enlarged views for explaining the process of forming the secondary seal. In FIGS. 4 and 5, for the sake of explanation, the outer surface 21s made of the end faces of each primary seal 21 has a thickness.

As shown in FIG. 3, a plurality of electrodes E including the bipolar electrode 14 are prepared (first step S1). In the first step S1, the bipolar electrode 14, the negative electrode terminal electrode 18, and the positive electrode terminal electrode 19 are prepared.

Next, the primary seal 21 is coupled to the peripheral edge portion 15c of the current collector 15 of each of the plurality of electrodes E (second step S2). In the second step S2, the primary seal 21 is coupled to the peripheral edge portion 15c of the current collector 15 included in the bipolar electrode 14, the negative electrode terminal electrode 18, and the positive electrode terminal electrode 19. As a result, the primary seal 21 is bonded to each of the bipolar electrode 14, the negative electrode terminal electrode 18, and the positive electrode terminal electrode 19.

Next, the electrode laminated body 11 is formed by laminating a plurality of electrodes E to which the primary seals 21 are bonded in the laminating direction D (third step S3). As a result, the negative electrode terminal electrode 18, the bipolar electrode 14, and the positive electrode terminal electrode 19 are laminated in the stacking direction D. At this time, the separator 13 is arranged between the adjacent electrodes E. In addition, each primary seal 21 is also laminated in the stacking direction D.

Next, the end faces 21b of the laminated primary seals 21 are temporarily joined to each other to form an outer surface 21s composed of the end faces 21b (fourth step S4). In the fourth step S4, for example, the hot plate is pressed against the end surface 21b of each primary seal 21 in a state where the electrode laminate 11 is fixed in the lamination direction D. The hot plate simultaneously presses and heats the end face 21b of the primary seal 21 to be laminated in the stacking direction D. As a result, the end face 21b and its periphery (that is, a part of the peripheral edge portion 21a) are melted, and the melted portion is deformed. Then, the end faces 21b of the adjacent primary seals 21 are temporarily joined to each other to form an end face welding layer including the outer face 21s. At this time, the plurality of electrodes E are also temporarily fixed. The primary seals 21 located at both ends in the stacking direction D correspond to the primary seal bonded to the negative electrode terminal electrode 18 and the primary seal bonded to the positive electrode terminal electrode 19.

Next, the secondary seal 22 that covers the outer surface 21s of the primary seal 21 is formed (fifth step S5). The fifth step S5 is a step of forming the first resin portion 23 covering the outer surface 21s of the primary seal 21 (sixth step) and a step of forming the second resin portion 24 covering the first resin portion 23 (seventh step). Step) and. After the fifth step S5, the seal member 12 is formed.

In the step of forming the first resin portion 23, for example, as shown in FIG. 4, the first resin portion 23 is formed by injection molding using the mold 40. The mold 40 has an upper mold 41 located on one side in the stacking direction D and a lower mold 42 located on the other side in the stacking direction D. The upper mold 41 and the lower mold 42 are located on opposite sides of each other in the stacking direction D. For example, the upper mold 41 contacts the primary seal 21 that is coupled to the negative electrode terminal electrode, and the lower mold 42 contacts the primary seal 21 that is coupled to the positive electrode terminal electrode. When the upper mold 41 and the lower mold 42 are combined, the space FS1 is defined on the outside of the primary seal 21. The space FS1 is defined so as to surround the outer surface 21s of the primary seal 21 in a plan view. The space FS1 is, for example, from a first portion extending in the stacking direction D like the outer surface 21s of the primary seal 21 and one end of the first portion in the stacking direction D to the center of the electrode laminate 11 in the plane direction. A third portion extending toward the center of the electrode laminate 11 in the plane direction from the second portion extending toward the other and the other end located opposite to the one end of the first portion in the stacking direction D. Has a part. The second portion is in contact with at least a part of the peripheral edge portion 21a of the primary seal 21 located at one end of the electrode laminate 11 in the lamination direction D. The third portion is in contact with at least a part of the peripheral edge portion 21a of the primary seal 21 located at the other end located on the opposite side of one end of the electrode laminate 11 in the stacking direction D. For example, only the peripheral edge portion 21a of each primary seal 21 is exposed in the space FS 1, but the space FS1 is not limited to this.

In the step of forming the first resin portion 23, the resin constituting the first resin portion 23 is introduced into the space FS1 from the injection port 43 which is a gap between the upper mold 41 and the lower mold 42. The resin is introduced into the space FS1 without gaps and then cured to form the first resin portion 23 that follows the shape of the space FS1. That is, the eaves portion extending in the stacking direction D and covering the outer surface 21s of the primary seal 21 and extending from one end of the main body portion 23a in the stacking direction D toward the center of the electrode laminated body 11 in the surface direction. The first resin portion 23 having the eaves portion 23c extending toward the center of the electrode laminate 11 in the plane direction from the other end located on the opposite side of the main body portion 23a in the stacking direction D and the 23b is formed. After the step of forming the first resin portion 23, at least the outer surface 21s of the primary seal 21 is covered with the first resin portion 23. In the present embodiment, in addition to the outer surface 21s, the peripheral edge portion 21a of the primary seal 21 bonded to the electrodes E located at both ends of the electrode laminate 11 is also covered with the first resin portion 23.

In the step of forming the second resin portion 24, for example, as shown in FIG. 5, the second resin portion 24 is formed by injection molding using the mold 50. The mold 50 has an upper mold 51 located on one side in the stacking direction D and a lower mold 52 located on the other side in the stacking direction D. The upper mold 51 and the lower mold 52 are located on opposite sides of each other in the stacking direction D. For example, the upper mold 51 contacts the primary seal 21 that is coupled to the negative electrode terminal electrode, and the lower mold 52 contacts the primary seal 21 that is coupled to the positive electrode terminal electrode. When the upper mold 51 and the lower mold 52 are combined in a state where the electrode laminate 11 provided with the first resin portion 23 is housed, a space FS2 is defined around the first resin portion 23. The space FS2 is defined so as to surround the first resin portion 23. The space FS 2 extends from one end of the fourth portion extending in the stacking direction D and the fourth portion extending in the stacking direction D toward the center of the electrode laminated body 11 in the plane direction as in the first resin portion 23. It has a fifth portion and a sixth portion extending from the other end located opposite to the one end of the fourth portion in the stacking direction D toward the center of the electrode laminate 11 in the plane direction. The fifth portion is in contact with the primary seal 21 located at one end of the electrode laminate 11 in the lamination direction D and the eaves portion 23b. The sixth portion is in contact with the primary seal 21 and the eaves portion 23c located at the other end located on the opposite side of the electrode laminate 11 in the stacking direction D. Therefore, the entire first resin portion 23 and a part of the primary seal 21 are exposed in the space FS2.

In the step of forming the second resin portion 24, the resin constituting the second resin portion 24 is introduced into the space FS2 from the injection port 53 which is a gap between the upper mold 51 and the lower mold 52. After the resin is introduced into the space FS2 without gaps, the resin is cured to form a second resin portion 24 that follows the shape of the space FS2. That is, it extends in the stacking direction D and extends from one end of the main body portion 24a covering the outer surface 23s of the first resin portion 23 and the main body portion 24a in the stacking direction D toward the center of the electrode laminated body 11 in the plane direction. A second resin portion 24 having an eaves portion 24b and an eaves portion 24c extending toward the center in the surface direction from the other end located on the opposite side of one end of the main body portion 24a in the stacking direction D is formed. After the step of forming the second resin portion 24, the first resin portion 23 is covered with the second resin portion 24.

After the step S5, the power storage module 4 is manufactured by carrying out a step of injecting an electrolytic solution into each internal space V or the like.

The effects exerted by the power storage module 4 manufactured by the manufacturing method according to the present embodiment described above will be described with reference to the following comparative examples. FIG. 6A is a schematic cross-sectional view of a main part for explaining a process of forming a secondary seal according to a first comparative example, and each of FIGS. 6B and 6C is a first comparative example. It is a schematic main part sectional view which shows the state after formation of the secondary seal which concerns on. FIG. 7A is a schematic cross-sectional view of a main part for explaining a step of forming the first resin portion according to the second comparative example, and FIG. 7B is a schematic cross-sectional view of the first resin according to the second comparative example. It is a schematic cross-sectional view of a main part which shows the state after formation of a part.

In the first comparative example, as shown in FIGS. 6A and 6B, the secondary seal 122 is molded by one injection molding. In this case, the resin injected when molding the secondary seal 122 may peel off a part of the primary seal 21 contained in the electrode laminate 11, so that the electrode to which the primary seal 21 is bonded may be rolled up. .. As a result, for example, as shown in FIG. 6B, a part of the primary seal 21 (and the electrode connected to the primary seal 21) may be located outside the secondary seal 122. Therefore, the sealing property of the power storage module may be insufficient.

Further, when the secondary seal 122 is injection-molded as in the first comparative example, the resin constituting the primary seal 21 may be melted. The flow of the molten resin toward the secondary seal 122 causes cracks in the resin constituting the secondary seal 122. In this case, as shown in FIG. 6C, a crack 122k is generated in a part of the secondary seal 122, and the pressure resistance strength of the seal member is lowered.

Here, the curling up of the electrode tends to occur, for example, at the edge of the mold or at the interface between the electrode and the primary seal. Therefore, in the second comparative example, as shown in FIG. 7A, in a state where the primary seals 21 located at both ends in the stacking direction are pressed by the upper mold 141 and the lower mold 142 of the mold 140, the second is 1 A method of injection molding the resin portion 123 is adopted. When this method is adopted, it is possible to prevent the primary seal 21 from peeling off and the electrodes from being curled up due to the formation of the first resin portion 123. However, the first resin portion 123 is located only on the outer surface 21s of the primary seal 21. Therefore, the fixing of the primary seal 21 by the first resin portion 123 tends to be insufficient. Therefore, when the second resin portion is formed, a part of the primary seal 21 may be peeled off, which may cause a part of the electrode E to be rolled up. Therefore, even in the second comparative example, the sealing property of the power storage module may be insufficient.

On the other hand, according to the power storage module 4 manufactured by the manufacturing method according to the present embodiment, the seal member 12 surrounding the electrode laminate 11 has a primary seal 21 and a secondary seal 22. By forming the seal member 12 with a plurality of members in this way, the sealability of the power storage module 4 can be improved. Further, the secondary seal 22 has a first resin portion 23 including a main body portion 23a that covers the outer surface 21s of the primary seal 21 and eaves portions 23b and 23c located at both ends of the main body portion 23a in the stacking direction D. In addition, the secondary seal 22 has a second resin portion 24 that surrounds the first resin portion 23. Therefore, the primary seal 21 is fixed so as to be gripped by the main body portion 23a and the eaves portions 23b and 23c of the first resin portion 23. As a result, it is possible to prevent the primary seal 21 and the electrode E to which the primary seal 21 is bonded from being rolled up during injection molding of the second resin portion 24. Therefore, the power storage module 4 can exhibit good sealing performance.

Further, in the present embodiment, the first resin portion 23 is remarkably smaller than the second resin portion 24. Therefore, when the first resin portion 23 is injection-molded as compared with the resin filling pressure when the secondary seal 122 (see FIGS. 6A and 6B) in the first comparative example is injection-molded. The filling pressure of the resin can be set to be remarkably small. As a result, even when the resin forming the first resin portion 23 is sprayed onto the primary seal 21 and the electrode E, the primary seal 21 is difficult to peel off and the electrode E is difficult to turn up.

In addition, in the present embodiment, the resin constituting the first resin portion 23 and the resin constituting the second resin portion 24 are the same as each other. Therefore, even when the resin constituting the first resin portion 23 is melted into the second resin portion 24 by the heat generated during injection molding of the second resin portion 24, the occurrence of cracks in the second resin portion 24 is suppressed. it can.

Further, according to the present embodiment, if the electrode E is rolled up during the formation of the first resin portion 23, the rolled up electrode E is fixed by the first resin portion 23. By forming the second resin portion 24 in this state, the rolled up electrode E can also be firmly fixed by the seal member 12. Therefore, even when a part of the electrodes E is rolled up, the sealing property of the power storage module 4 can be ensured. Further, according to the present embodiment, even if the first resin portion 23 is cracked, the first resin portion 23 is covered with the second resin portion 24. As a result, the pressure resistance of the seal member 12 can be ensured.

In the present embodiment, the second resin portion 24 extends in the stacking direction D and covers the outer surface 23s of the first resin portion 23, and the electrode in the plane direction from one end of the main body portion 24a in the stacking direction D. In addition to extending toward the center of the laminated body 11, the eaves portion 24b covering the eaves portion 23b and the other end of the main body portion 24a in the stacking direction D extend toward the center of the electrode laminated body 11 in the plane direction. It has an eaves portion 24c that covers the eaves portion 23c. For example, when the first resin portion 23 is formed, a part of the electrodes E may be rolled up, so that the part of the electrodes E may be located outside the eaves portion 23b or the eaves portion 23c of the first resin portion 23. Even in this case, the sealing property of the power storage module 4 can be satisfactorily secured by fixing a part of the electrodes E by the eaves portion 24b or the eaves portion 24c of the second resin portion 24.

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment. For example, in the above embodiment, the end faces of adjacent primary seals are welded to each other, but the present invention is not limited to this. The plurality of primary seals to be laminated need not be welded to each other. That is, the end face welding layer and the outer surface need not be formed by the primary seal. Alternatively, only a part of the plurality of laminated primary seals may be welded.

Further, in the above embodiment, the second resin portion completely covers the first resin portion, but the present invention is not limited to this. For example, a part of the first resin portion may be exposed from the second resin portion. When a part of the first resin part is exposed from the second resin part, a part of the eaves part of the first resin part may be exposed. In this case, the inner peripheral surface of the eaves portion of the first resin portion may be exposed from the second resin portion in a plan view. When the inner peripheral surface of the eaves portion of the first resin portion is exposed from the second resin portion, the inner peripheral surface of the eaves portion of the first resin portion and the inner peripheral surface of the eaves portion of the second resin portion are They may be aligned with each other.

Further, in the above embodiment, the secondary seal has only the first and second resin parts, but is not limited to this. For example, the secondary seal may have a third resin portion that seals the outer surface of the second resin portion in addition to the first and second resin portions. In this case, the step of forming the secondary seal is a step of forming a third resin portion that covers the outer surface (third outer surface) of the second resin portion in addition to the step of forming the first and second resin portions. (Eighth step). When the secondary seal has a third resin portion, the first resin portion may be covered with the second resin portion and the third resin portion. For example, the second resin portion has a main body portion that covers the outer surface of the first resin portion and an eaves portion (third eaves portion) that covers one eaves portion (first eaves portion) in the first resin portion. You may. The third resin portion has a main body portion that covers the outer surface of the second resin portion and an eaves portion (fifth eaves portion) that covers the other eaves portion (second eaves portion) in the first resin portion. You may. Here, the eaves portion of the second resin portion and the eaves portion of the third resin portion may completely cover the eaves portion of the first resin portion, but the present invention is not limited to this. By covering the first resin portion with the plurality of resin portions in this way, the power storage module can be satisfactorily sealed.

In the above embodiment, the gap between the upper mold and the lower mold corresponds to the injection port, but the present invention is not limited to this. For example, the injection port may be provided on either the upper mold or the lower mold. In this case, the mold for forming the first resin portion may be provided with an injection port on the upper mold, and the mold for forming the second resin portion may be provided with an injection port on the lower mold.

In the above embodiment, the primary seal exhibits a single layer structure, but is not limited to this. The primary seal may exhibit a laminated structure. In this case, the primary seal may be formed by folding a single frame-like member.

4 ... Power storage module, 11 ... Electrode laminate, 12 ... Seal member, 14 ... Bipolar electrode, 15 ... Current collector, 15c ... Peripheral part, 21 ... Primary seal, 21s ... Outer surface (first outer surface), 22 ... Secondary seal, 23 ... 1st resin part, 23a ... Main body part (1st main body part), 23b ... Eaves part (1st eaves part), 23c ... Eaves part (2nd eaves part), 23s ... Outer surface (1st) 2 outer surface), 24 ... 2nd resin part, 24a ... main body part (2nd main body part), 24b ... eaves part (3rd eaves part), 24c ... eaves part (4th eaves part), D ... stacking direction ( 1st direction), E ... electrode, V ... internal space.

Claims (6)

A plurality of electrodes including a current collector, a positive electrode provided on one surface of the current collector, and a bipolar electrode having a negative electrode provided on the other surface of the current collector are arranged along a first direction via a separator. And the electrode laminate made by laminating
A seal member that surrounds the electrode laminate is provided.
The seal member has a primary seal provided on the peripheral edge of the current collector and a secondary seal that covers the primary seal.
The secondary seal includes a first resin portion that covers the first outer surface formed by laminating the end faces of the primary seal along the first direction, and a second resin that covers the second outer surface of the first resin portion. Has a part and
The first resin part is
A first main body portion extending in the first direction and covering the first outer surface,
A first eaves portion extending from one end of the first main body portion in the first direction toward the center of the electrode laminate in a plane direction intersecting with the first direction.
It has a second eaves portion extending from the other end of the first main body portion in the first direction toward the center of the electrode laminate in the plane direction.
Power storage module. The second resin part is
A second main body portion that extends in the first direction and covers the second outer surface of the first resin portion.
A third eaves portion that extends from one end of the second main body portion in the first direction toward the center of the electrode laminate in the surface direction and covers the first eaves portion.
Claimed to have a fourth eaves portion extending from the other end of the second main body portion in the first direction toward the center of the electrode laminate in the plane direction and covering the second eaves portion. Item 2. The power storage module according to item 1. The secondary seal further has a third resin portion that covers the third outer surface of the second resin portion.
The power storage module according to claim 1, wherein the first resin portion is covered with the second resin portion and the third resin portion. The first step of preparing a plurality of electrodes having bipolar electrodes,
A second step of connecting the primary seal to the peripheral edge of the current collector of each of the plurality of electrodes, and
A third step of forming an electrode laminate by laminating the plurality of electrodes in the first direction, and
A fourth step of forming a first outer surface composed of the end faces by temporarily joining the end faces of the primary seals laminated along the first direction.
A fifth step of forming a secondary seal covering the first outer surface, and
With
The fifth step is
A first main body portion extending in the first direction and covering the first outer surface, and a center of the electrode laminate in a plane direction intersecting the first direction from one end of the first main body portion in the first direction. Extends from the first eaves portion extending toward the center of the electrode laminate and the other end located on the opposite side of the first main body portion in the first direction toward the center of the electrode laminate in the plane direction. The sixth step of forming the first resin portion having the second eaves portion and
It has a seventh step of forming a second resin portion that covers the second outer surface of the first resin portion.
Manufacturing method of power storage module. In the seventh step,
A second main body portion that extends in the first direction and covers the second outer surface of the first resin portion.
A third eaves portion that extends from one end of the second main body portion in the first direction toward the center of the electrode laminate in the surface direction and covers the first eaves portion.
A claim that extends from the other end of the second main body portion in the first direction toward the center of the electrode laminate in the plane direction, and forms a fourth eaves portion that covers the second eaves portion. Item 4. The method for manufacturing a power storage module according to item 4. The fifth step further includes an eighth step of forming a third resin portion that covers the third outer surface of the second resin portion.
The method for manufacturing a power storage module according to claim 4, wherein the first resin portion is covered with the second resin portion and the third resin portion.

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