JP7172904B2 - Storage module and method for manufacturing storage module - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electric storage module and a method for manufacturing an electric storage module.

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

JP 2011-204386 A

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

An object of the present invention is to provide an electricity storage module and a method for manufacturing an electricity storage module that can exhibit good sealing properties.

An electricity storage module according to one aspect of the present invention includes a current collector, a plurality of electrodes including a bipolar electrode having a positive electrode provided on one side of the current collector and a negative electrode provided on the other side of the current collector, The electrode stack includes an electrode stack stacked along a first direction with separators interposed therebetween, and a sealing member surrounding the electrode stack. The seal member has a primary seal provided on the peripheral edge of the current collector and a secondary seal covering the primary seal, and the secondary seal is formed by laminating the end faces of the primary seal along the first direction. and a second resin portion covering the second outer surface of the first resin portion, the first resin portion extending in the first direction and the first a first main body covering an outer surface; a first overhang extending from one end of the first main body in the first direction toward the center of the electrode stack in a plane direction intersecting the first direction; a second eaves portion extending from the other end of the first main body portion in the planar direction toward the center of the electrode laminate.

In this power storage module, the sealing member surrounding the electrode laminate has a primary seal and a secondary seal. By configuring the sealing member with a plurality of members in this manner, the sealing performance of the power storage module can be improved. In addition, the secondary seal includes a first main body portion covering a first outer surface formed by stacking end faces of the primary seals along the first direction, and first main body portions positioned at both ends of the first main body portion in the first direction. It has a first resin portion including an eaves portion and a second eaves portion. Therefore, the primary seal is held and fixed by the first 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 (seal) can be prevented from curling up. Therefore, the power storage module can exhibit good sealing properties.

The second resin portion includes: a second body portion extending in the first direction and covering a second outer surface of the first resin portion; a third eaves portion covering the first eaves portion and extending toward the center of the electrode laminate in the plane direction from the other end of the second body portion in the first direction, You may have a 4th eaves part which covers an eaves part. For example, a portion of the electrodes may be curled up during the formation of the first resin portion, so that the portion of the electrodes may be positioned outside the first eaves portion or the second eaves portion of the first resin portion. Even in this case, it is possible to ensure the sealing performance of the power storage module by fixing the partial electrodes with the third eaves portion or the fourth eaves portion of the second resin portion.

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

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

In this electricity storage module manufacturing method, a primary seal and a secondary seal are formed. By sealing the electrode laminate with a plurality of members in this manner, the sealing performance of the power storage module can be improved. In addition, the fifth step of forming the secondary seal includes a first main body portion covering a first outer surface formed by the end faces of the temporarily joined primary seal, and positioned at both ends of the first main body portion in the first direction. A sixth step of forming a first resin portion including a first eaves portion and a second eaves portion is provided. As a result, the primary seal is gripped and fixed by the first 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 edge of the current collector) may be rolled up. can be prevented. Therefore, the power storage module manufactured by the manufacturing method described above can exhibit good sealing properties.

In the seventh step, a second body portion extending in the first direction and covering the second outer surface of the first resin portion; a third eaves portion covering the first eaves portion and extending toward the center of the electrode laminate in the plane direction from the other end of the second body portion in the first direction, You may form the 4th eaves part which covers an eaves part. For example, a part of the electrode may be curled up during the process of forming the first resin part, and the part of the electrode may be located outside the first eaves part or the second eaves part of the first resin part. . Even in this case, it is possible to ensure the sealing performance of the power storage module by fixing the partial electrodes with 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 covering the third outer surface of the second resin portion, wherein the first resin portion is covered with the second resin portion and the third resin portion. may In this case, by covering the first resin portion with the second resin portion and the third resin portion, the power storage module can be well sealed.

ADVANTAGE OF THE INVENTION According to one aspect of the present invention, it is possible to provide an electricity storage module and a method for manufacturing an electricity storage module that can exhibit good sealing properties.

FIG. 1 is a schematic cross-sectional view of a power storage device including power storage modules. 2 is a schematic cross-sectional view showing the internal configuration of the power storage module shown in FIG. 1. FIG. FIG. 3 is a flow chart for explaining a method for manufacturing an electric storage module. FIG. 4 is a schematic enlarged view for explaining the step of forming the secondary seal. FIG. 5 is a schematic enlarged view for explaining the step of forming the secondary seal. FIG. 6(a) is a schematic cross-sectional view of main parts for explaining a step of forming a secondary seal according to the first comparative example, and FIGS. 2 is a schematic cross-sectional view of main parts showing a state after formation of a secondary seal according to FIG. FIG. 7A is a schematic cross-sectional view of main parts for explaining a step of forming a first resin portion according to a second comparative example, and FIG. 7B is a first resin portion according to the second comparative example. FIG. 4 is a schematic cross-sectional view of main parts showing a state after formation of a part;

BEST MODE FOR CARRYING OUT THE INVENTION 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 overlapping descriptions are omitted.

First, referring to FIG. 1, the configuration of a power storage device including power storage modules manufactured by the method for manufacturing power storage modules according to the present embodiment will be described. FIG. 1 is a schematic cross-sectional view of a power storage device including power storage modules. A power storage device 1 shown in FIG. 1 is used, for example, as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 includes a module laminate 2 including a plurality of stacked power storage modules 4 and a binding member 3 that applies a binding load to the module laminate 2 . Hereinafter, the direction in which the power storage modules 4 are stacked is simply referred to as "stacking direction D (first direction)". A direction intersecting or perpendicular to the stacking direction D is defined as a planar direction. Planar directions include, for example, an X-axis direction and a Y-axis direction that are orthogonal to each other. In the present embodiment, "viewed from the stacking direction D" corresponds to planar view.

The module stack 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. As shown in FIG. The power storage module 4 is, for example, a secondary battery such as a nickel-hydrogen secondary battery or a lithium-ion secondary battery, an electric double layer capacitor, or the like. In the following description, a nickel-metal hydride secondary battery is exemplified as the power storage module 4 .

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

The conductive structure 5 can also function as a heat sink in the power storage device 1 . The conductive structure 5 may, for example, dissipate heat generated in the storage module 4 . Inside the conductive structure 5, a plurality of flow paths 5a for circulating a coolant such as air are provided. The channel 5a extends, for example, along the direction D3. By passing a coolant such as air through these flow paths 5a, the heat generated in 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 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 may be larger than the area of the power storage module 4 in plan view.

The restraint member 3 is a member that restrains the storage module 4 in the stacking direction D, and includes a pair of end plates 8 that sandwich the module stack 2 in the stacking direction D, and a fastening bolt 9 and a nut 10 that fasten the end plates 8 together. have Therefore, the restraining force of the restraining member 3 is applied to the module laminate 2 via the conductive structure 5 . The end plate 8 is a metal plate having an area slightly larger than the area of the storage module 4 and the conductive structure 5 when viewed in 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 provides insulation between the end plate 8 and the conductive structure 5 (or between the end plate 8 and the storage module 4).

An insertion hole 8 a is provided in the edge of the end plate 8 at a position outside the module stack 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 the tip portion of the fastening bolt 9 protruding from the insertion hole 8a of the other end plate 8 has a , a nut 10 is screwed. As a result, the storage module 4 and the conductive structure 5 are sandwiched between the end plates 8 and unitized as the module laminate 2 . Further, a restraining force along the stacking direction D is applied to the unitized module stack 2 .

Next, the configuration of the power storage module 4 will be described in more detail. 2 is a schematic cross-sectional view showing the internal configuration of the power storage module shown in FIG. 1. FIG. As shown in the figure, the electricity storage module 4 includes an electrode laminate 11 including a plurality of electrodes E laminated in the lamination direction D, and a seal member 12 surrounding the electrode laminate 11 when viewed from the lamination direction D. there is A space between the electrode laminate 11 and the sealing member 12 is sealed.

The electrode stack 11 includes a plurality of electrodes E stacked in a stacking direction D with separators 13 interposed therebetween. The plurality of electrodes E includes bipolar electrodes 14 , negative terminal electrodes 18 and positive terminal electrodes 19 . The bipolar electrode 14 includes a current collector 15, a positive electrode 16 provided on one surface 15a of the current collector 15, and a positive electrode 16 included in the current collector 15 and on the other surface 15b located on the opposite side of the one surface 15a in the stacking direction D. It includes a negative electrode 17 provided. The positive electrode 16 is a positive electrode active material layer formed by applying a positive electrode active material onto one surface 15a. Negative electrode 17 is a negative electrode active material layer formed by coating a negative electrode active material on the other surface 15b. In the electrode stack 11 , the positive electrode 16 of one bipolar electrode 14 faces the negative electrode 17 of one bipolar electrode 14 adjacent in the stacking direction D with the separator 13 interposed therebetween. In the electrode stack 11 , the negative electrode 17 of one bipolar electrode 14 faces the positive electrode 16 of the other bipolar electrode 14 adjacent in the stacking direction D with the separator 13 interposed therebetween.

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

The current collector 15 is a plate-shaped conductor 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 steel sheets include cold-rolled steel sheets (SPCC, etc.) defined in JIS G 3141:2005. Examples of the stainless steel plate include SUS304, SUS316, etc. specified in JIS G 4305:2015. A peripheral edge portion 15c of the current collector 15 (peripheral edge portion of the bipolar electrode 14) has a rectangular frame shape and is an uncoated region where the positive electrode active material and the negative electrode active material are not coated. Examples of the positive electrode active material forming the positive electrode 16 include nickel hydroxide. Nickel hydroxide may be coated with cobalt oxide or the like. Examples of negative electrode active materials that constitute the negative electrode 17 include hydrogen storage alloys. In this embodiment, the formation area of the negative electrode 17 on the other surface 15 b of the current collector 15 is one size larger than the formation area of the positive electrode 16 on the one surface 15 a 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 polyolefin resin such as polyethylene (PE) or polypropylene (PP). The separator 13 may be a woven fabric or non-woven fabric made of polypropylene, methyl cellulose, or the like. Separator 13 may be reinforced with a vinylidene fluoride resin compound. Note that the separator 13 is not limited to a sheet shape, and may be a bag shape.

The sealing member 12 is a resin member configured to surround the electrode laminate 11 . The sealing member 12 is provided so as to surround the peripheral portion 15 c of the current collector 15 . The sealing member 12 is formed in a rectangular frame shape by using an insulating resin, for example. Examples of the resin forming the sealing 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 portion 15 c and a secondary seal 22 covering the primary seal 21 .

The primary seal 21 is a resin member coupled 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. As shown in FIG. The primary seal 21 is continuously welded over the entire circumference of the peripheral portion 15c by, for example, ultrasonic waves or heat. The primary seal 21 is provided, for example, on the peripheral edge portion 15c of the current collector 15 on the side of the other surface 15b. A primary seal 21 is provided on the peripheral edge portion 15c on the one surface 15a side of the current collector 15 included in the negative terminal electrode 18 . A primary seal 21 is provided on both the peripheral edge portion 15 c on the one surface 15 a side and the peripheral edge portion 15 c on the other surface 15 b side of the current collector 15 included in the positive terminal electrode 19 . The primary seal 21 is provided apart from the positive electrode 16 and the negative electrode 17 when viewed in the stacking direction D. As shown in FIG. The peripheral edge portions 21a of the primary seals 21 adjacent in the stacking direction D may contact 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.

A peripheral edge portion 21a of the primary seal 21 in a plan view is at least part of a region located outside the current collector 15 in the plane direction, and has an end surface 21b located on the outermost side in the plane direction. At least part of the peripheral portion 21 a 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 together. In this embodiment, the peripheral edges 21a of all the laminated primary seals 21 are welded to each other. outer surface) is formed. In addition, by welding the peripheral edge portions 21a together, an end face welded layer is formed which has a substantially rectangular frame shape in a plan view and extends along the stacking direction D. As shown in FIG. The outer surface 21s is an outer peripheral surface extending along the stacking direction D and is a part of the end surface weld layer.

The secondary seal 22 is a resin member forming 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, for example, by injection molding of resin as will be described later, and extends over the entire length of the electrode laminate 11 in the lamination direction D. As shown in FIG. The secondary seal 22 is a rectangular cylindrical member extending with the stacking direction D as an 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 this embodiment, the secondary seal 22 completely covers the outer surface 21s of the primary seal 21 extending in the stacking direction D. As shown in FIG. The secondary seal 22 is welded to the outer surface 21s of the primary seal 21 by heat during injection molding, for example. The resin forming the primary seal 21 and the resin forming the secondary seal 22 are compatible with each other. The primary seal 21 is made of PP, for example, and the secondary seal 22 is made of modified PPE, for example.

The secondary seal 22 includes a first resin portion 23 covering an outer surface 21s composed of the primary seals 21 stacked along the stacking direction D, and an outer surface 23s (second outer surface) of the first resin portion 23. and a surrounding second resin portion 24 . The first resin portion 23 is a portion for temporarily fixing the electrode laminate 11 coupled with the primary seal 21, and has, for example, a rectangular cylindrical shape. Therefore, the first resin portion 23 has a rectangular frame shape in 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 becomes the outer wall of the power storage module, and has, for example, a rectangular tubular shape. Therefore, the second resin portion 24 also has a rectangular frame shape in plan view. The resin forming the first resin portion 23 and the resin forming the second resin portion 24 are the same as each other, such as modified PPE.

The first resin portion 23 includes a body portion 23a (first body portion) extending in the stacking direction D and extending from one end of the body portion 23a in the stacking direction D toward the center of the electrode stack 11 in the planar 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 laminate 11 in the plane direction. The main body portion 23a is a portion that covers the outer side surface 21s formed by the primary seals 21 and seals the adjacent primary seals 21. As shown in FIG. One end of the main body portion 23a corresponds to the end on the positive terminal electrode 19 side in the stacking direction D, and the other end of the main body portion 23a corresponds to the end on the negative terminal electrode 18 side in the stacking direction D. One end of the body portion 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, respectively.

The eaves portion 23b is a portion that covers, for example, the peripheral edge portion 21a of the primary seal 21 coupled to the negative terminal electrode 18, and has a substantially rectangular frame shape in plan view. The eaves portion 23b extends along the surface direction. The eaves portion 23c is a portion that covers, for example, the peripheral edge portion 21a of the primary seal 21 coupled to the positive terminal electrode 19, and has a substantially rectangular frame shape in plan view. The eaves portion 23c extends along the surface direction. In the present embodiment, each of the eaves portions 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 plan view. However, it is not limited to this. Each of the eaves portions 23b and 23c may or may not overlap the current collector 15 in plan view.

The second resin portion 24 includes a body portion 24a (second body portion) extending in the stacking direction D and extending from one end of the body portion 24a in the stacking direction D toward the center of the electrode stack 11 in the planar 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 laminate 11 in the plane direction. The body portion 24 a is a portion that covers the outer side surface 23 s of the first resin portion 23 . One end of the main body portion 24a corresponds to the end on the positive terminal electrode 19 side in the stacking direction D, and the other end of the main body portion 24a corresponds to the end on the negative terminal electrode 18 side in the stacking direction D. 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, respectively.

The eaves portion 24b is a portion that covers the eaves portion 23b, and has a substantially rectangular frame shape in plan view. The eaves portion 24b extends along the surface direction. The eaves portion 24c is a portion that covers the eaves portion 23c, and has a substantially rectangular frame shape extending in the plane direction. The eaves portion 24c extends along the surface direction. In the present embodiment, each of the eaves portions 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 plan view. No, but not limited to. Each of the eaves portions 24b and 24c may or may not overlap the current collector 15 in 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. As shown in FIG. The internal space V is a space between the current collectors 15 adjacent in the stacking direction D and partitioned airtight and watertight by the current collectors 15 and the sealing member 12 . This internal space V contains, for example, an electrolytic solution (not shown). The electrolytic solution is, for example, an aqueous electrolytic solution (specific examples include an aqueous potassium hydroxide solution, an aqueous lithium hydroxide solution, or a mixed solution thereof). It is impregnated into the separator 13 , positive electrode 16 and negative electrode 17 . 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 .

Next, an example of a method for manufacturing the electricity storage module 4 will be described with reference to FIGS. 3 to 5. FIG. FIG. 3 is a flow chart for explaining a method for manufacturing an electric 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, which is the end surface of each primary seal 21, has a thickness.

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

Next, the primary seal 21 is bonded 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 S<b>2 , the primary seal 21 is bonded to the peripheral edge portion 15 c of the current collector 15 included in the bipolar electrode 14 , the negative terminal electrode 18 and the positive terminal electrode 19 . Thereby, the primary seal 21 is bonded to each of the bipolar electrode 14 , the negative terminal electrode 18 and the positive terminal electrode 19 .

Next, the electrode stack 11 is formed by stacking a plurality of electrodes E coupled with the primary seals 21 in the stacking direction D (third step S3). Thereby, the negative terminal electrode 18, the bipolar electrode 14, and the positive terminal electrode 19 are stacked in the stacking direction D. As shown in FIG. At this time, the separator 13 is arranged between the electrodes E adjacent to each other. In addition, each primary seal 21 is also laminated in the lamination direction D.

Next, the end faces 21b of the laminated primary seals 21 are temporarily joined to form the outer side faces 21s composed of the end faces 21b (fourth step S4). In the fourth step S4, for example, a hot plate is pressed against the end surface 21b of each primary seal 21 while the electrode laminate 11 is fixed in the stacking direction D. As shown in FIG. The hot plate presses and heats the end surfaces 21b of the primary seals 21 stacked in the stacking direction D at the same time. As a result, the end surface 21b and its periphery (that is, part of the peripheral 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 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 a primary seal that joins the negative terminal electrode 18 and a primary seal that joins the positive terminal electrode 19 .

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

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

In the step of forming the first resin portion 23 , the resin forming the first resin portion 23 is introduced into the space FS<b>1 from the injection port 43 that is the gap between the upper mold 41 and the lower mold 42 . The first resin portion 23 is formed along the shape of the space FS1 by curing the resin after being introduced into the space FS1 without gaps. That is, a main body portion 23a that extends in the stacking direction D and covers the outer surface 21s of the primary seal 21, and an eaves portion that extends from one end of the main body portion 23a in the stacking direction D toward the center of the electrode stack 11 in the planar direction. 23b, and an eaves portion 23c extending from the other end opposite to the one end of the main body portion 23a in the stacking direction D toward the center of the electrode stack 11 in the planar direction. After the step of forming the first resin portion 23 , at least the outer surface 21 s of the primary seal 21 is covered with the first resin portion 23 . In this embodiment, in addition to the outer surface 21 s , the peripheral edge portion 21 a of the primary seal 21 coupled 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 a 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. As shown in FIG. The upper mold 51 and the lower mold 52 are positioned on opposite sides in the stacking direction D. As shown in FIG. For example, the top mold 51 contacts the primary seal 21 that bonds to the negative terminal electrode and the bottom mold 52 contacts the primary seal 21 that bonds to the positive terminal electrode. A space FS2 is defined around the first resin portion 23 when the upper mold 51 and the lower mold 52 are combined in a state in which the electrode laminate 11 provided with the first resin portion 23 is accommodated. Space FS2 is defined so as to surround first resin portion 23 . The space FS2 includes a fourth portion extending in the stacking direction D similarly to the first resin portion 23 and extending from one end of the fourth portion in the stacking direction D toward the center of the electrode stack 11 in the planar direction. It has a fifth portion and a sixth portion extending from the other end of the fourth portion in the stacking direction D opposite to the one end of the electrode stack 11 in the planar direction toward the center of the electrode stack 11 . The fifth portion is in contact with the primary seal 21 positioned at one end of the electrode laminate 11 in the stacking 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 of the electrode laminate 11 opposite to the one end of the electrode laminate 11 in the stacking direction D. As shown in FIG. Therefore, the entire first resin portion 23 and part of the primary seal 21 are exposed to the space FS2.

In the step of forming the second resin portion 24 , the resin forming the second resin portion 24 is introduced into the space FS<b>2 from the injection port 53 that is the gap between the upper mold 51 and the lower mold 52 . After the resin is tightly introduced into the space FS2, the resin is cured to form the second resin portion 24 along the shape of the space FS2. That is, the main body portion 24a that extends in the stacking direction D and covers the outer side surface 23s of the first resin portion 23, extends from one end of the main body portion 24a in the stacking direction D toward the center of the electrode stack 11 in the planar direction. A second resin portion 24 is formed having an eaves portion 24b and an eaves portion 24c extending from the other end opposite to one end of the main body portion 24a in the stacking direction D toward the center in the planar direction. After the step of forming the second resin portion 24 , the first resin portion 23 is covered with the second resin portion 24 .

After step S<b>5 , the electric storage module 4 is manufactured by performing a step of injecting an electrolytic solution into each internal space V, and the like.

The operational effects of the power storage module 4 manufactured by the manufacturing method according to the present embodiment described above will be described using comparative examples shown below. FIG. 6(a) is a schematic cross-sectional view of main parts for explaining a step of forming a secondary seal according to the first comparative example, and FIGS. 2 is a schematic cross-sectional view of main parts showing a state after formation of a secondary seal according to FIG. FIG. 7A is a schematic cross-sectional view of main parts for explaining a step of forming a first resin portion according to a second comparative example, and FIG. 7B is a first resin portion according to the second comparative example. FIG. 4 is a schematic cross-sectional view of main parts showing a 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, a part of the primary seal 21 included in the electrode laminate 11 is peeled off by the resin injected when the secondary seal 122 is molded, and the electrode coupled with the primary seal 21 may be turned up. . This may result in a portion of the primary seal 21 (and the electrodes coupled thereto) being located outside of the secondary seal 122, as shown in FIG. 6(b), for example. Therefore, the sealing performance 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 forming the primary seal 21 may melt. The flow of this molten resin toward the secondary seal 122 causes cracks in the resin forming the secondary seal 122 . In this case, as shown in FIG. 6(c), a crack 122k occurs 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. For this reason, in the second comparative example, as shown in FIG. 7A, the primary seals 21 positioned at both ends in the stacking direction are pressed by the upper die 141 and the lower die 142 of the die 140, and the primary seals 21 are pressed. 1 A method of injection molding the resin portion 123 is employed. When this method is employed, peeling of the primary seal 21 and accompanying swelling of the electrode can be prevented during the formation of the first resin portion 123 . However, the first resin portion 123 is positioned only on the outer side surface 21s of the primary seal 21 . Therefore, 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, and as a result, a part of the electrode E may be curled up. Therefore, even in the second comparative example, the sealing performance of the power storage module may be insufficient.

In contrast, 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 the primary seal 21 and the secondary seal 22 . By configuring the sealing member 12 with a plurality of members in this manner, the sealing performance 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 covering the outer side 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. Additionally, the secondary seal 22 has a second resin portion 24 surrounding the first resin portion 23 . Therefore, the main body portion 23a and the eaves portions 23b and 23c of the first resin portion 23 are fixed so that the primary seal 21 is gripped. As a result, it is possible to prevent the primary seal 21 and the electrode E to which the primary seal 21 is coupled from curling up during the injection molding of the second resin portion 24 . Therefore, the power storage module 4 can exhibit good sealing properties.

Also, in the present embodiment, the first resin portion 23 is significantly smaller than the second resin portion 24 . Therefore, compared with the filling pressure of the resin when injection molding the secondary seal 122 (see FIGS. 6A and 6B) in the first comparative example, when the first resin portion 23 is injection molded, The filling pressure of the resin can be set remarkably small. Accordingly, 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 less likely to peel off and the electrode E is less likely to be turned up.

In addition, in the present embodiment, the resin forming the first resin portion 23 and the resin forming the second resin portion 24 are the same as each other. Therefore, even if the resin forming the first resin portion 23 melts into the second resin portion 24 due to the heat generated during the injection molding of the second resin portion 24, the occurrence of cracks in the second resin portion 24 is suppressed. can.

Furthermore, according to the present embodiment, if the electrode E is curled up during the formation of the first resin portion 23 , the curled up electrode E is fixed by the first resin portion 23 . By forming the second resin portion 24 in this state, the curled electrode E can be firmly fixed by the sealing member 12 . Therefore, even if some of the electrodes E are rolled up, it is possible to ensure the sealing performance of the power storage module 4 . Moreover, 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 . Thereby, the pressure resistance strength of the sealing member 12 can be ensured.

In this embodiment, the second resin portion 24 includes a body portion 24a that extends in the stacking direction D and covers the outer side surface 23s of the first resin portion 23, and an electrode in the plane direction from one end of the body portion 24a in the stacking direction D. Extends toward the center of the electrode laminate 11 and extends toward the center of the electrode laminate 11 in the planar direction from the eaves portion 24b covering the eaves portion 23b and the other end of the main body portion 24a in the lamination direction D. , and a canopy portion 24c that covers the canopy portion 23c. For example, when the first resin portion 23 is formed, a part of the electrode E may be rolled up, and the part of the electrode E may be positioned outside the eaves portion 23b or the eaves portion 23c of the first resin portion 23 . Even in this case, by fixing some of the electrodes E with the eaves portion 24b or the eaves portion 24c of the second resin portion 24, the sealing performance of the electricity storage module 4 can be ensured satisfactorily.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments. For example, in the above embodiment, the end faces of adjacent primary seals are welded together, but the present invention is not limited to this. Multiple primary seals that are stacked may not be welded together. That is, the end face weld layer and the outer face need not be formed by the primary seal. Alternatively, only some of the laminated primary seals may be welded.

Moreover, although the second resin portion completely covers the first resin portion in the above embodiment, the present invention is not limited to this. For example, part of the first resin portion may be exposed from the second resin portion. When a portion of the first resin portion is exposed from the second resin portion, a portion of the eaves portion of the first resin portion 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 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 may align with each other.

Moreover, in the above embodiment, the secondary seal has only the first and second resin portions, but the present invention is not limited to this. For example, the secondary seal may have, in addition to the first and second resin portions, a third resin portion that seals the outer surface of the second resin portion. In this case, the step of forming the secondary seal is the step of forming the third resin portion covering the outer surface (third outer surface) of the second resin portion in addition to the step of forming the first and second resin portions. (8th step). If the secondary seal has a third resin portion, the first resin portion may be covered by the second resin portion and the third resin portion. For example, the second resin portion has a 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) of the first resin portion. may The third resin portion has a 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) of the first resin portion. 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 a plurality of resin portions in this manner, the power storage module can be sealed well.

In the above embodiment, the gap between the upper mold and the lower mold corresponds to the injection port, but it is not limited to this. For example, the injection port may be provided in one of the upper mold and the lower mold. In this case, the mold for forming the first resin portion may be provided with an injection port in the upper mold, and the mold for forming the second resin portion may be provided with an injection port in the lower mold.

In the above embodiments, 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 sealing member 14 bipolar electrode 15 current collector 15c peripheral portion 21 primary seal 21s outer surface (first outer surface) 22 Secondary seal 23... First resin part 23a... Main body part (first main body part) 23b... Eaves part (first eaves part) 23c... Eaves part (second eaves part) 23s... Outside surface (second eaves part) 2 outer surface), 24... Second resin portion, 24a... Main body part (second main body part), 24b... Eaves part (third eaves part), 24c... Eaves part (fourth eaves part), D... Lamination direction ( first direction), E... electrode, V... internal space.

Claims (6)

A plurality of electrodes including a bipolar electrode having a current collector, a positive electrode provided on one side of the current collector, and a negative electrode provided on the other side of the current collector are arranged along a first direction with separators interposed therebetween. an electrode laminate formed by laminating by
a sealing member surrounding the electrode laminate,
The seal member has a primary seal provided on the peripheral edge of the current collector and a secondary seal covering the primary seal,
The secondary seal includes a first resin portion covering a first outer surface formed by laminating end surfaces of the primary seal along the first direction, and a second resin covering a second outer surface of the first resin portion. and
The first resin portion is
a first main body extending in the first direction and covering the first outer surface;
a first eaves portion extending from one end of the first body portion in the first direction toward the center of the electrode laminate in a plane direction intersecting the first direction;
a second eaves portion extending from the other end of the first body portion in the first direction toward the center of the electrode laminate in the planar direction;
storage module. The second resin portion is
a second body portion extending in the first direction and covering the second outer surface of the first resin portion;
a third eaves portion extending from one end of the second body portion in the first direction toward the center of the electrode laminate in the planar direction and covering the first eaves portion;
a fourth eaves portion extending from the other end of the second body portion in the first direction toward the center of the electrode laminate in the surface direction and covering the second eaves portion; Item 1. The power storage module according to item 1. The secondary seal further has a third resin portion covering a 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. a first step of providing a plurality of electrodes comprising bipolar electrodes;
a second step of bonding a primary seal to a peripheral portion of a current collector of each of the plurality of electrodes;
a third step of forming an electrode stack by stacking the plurality of electrodes in a first direction;
a fourth step of temporarily joining the end faces of the primary seals stacked along the first direction to form a first outer surface composed of the end faces;
a fifth step of forming a secondary seal over the first outer surface;
with
The fifth step is
a first main body extending in the first direction and covering the first outer side surface; and a center of the electrode laminate in a plane direction intersecting the first direction from one end of the first main body in the first direction. and a first eaves portion extending toward the center of the electrode laminate in the planar direction from the other end of the first main body portion located on the side opposite to the one end in the first direction. a sixth step of forming a first resin portion having a second eaves portion that
a seventh step of forming a second resin portion covering a second outer surface of the first resin portion;
A method for manufacturing a power storage module. In the seventh step,
a second body portion extending in the first direction and covering the second outer surface of the first resin portion;
a third eaves portion extending from one end of the second body portion in the first direction toward the center of the electrode laminate in the planar direction and covering the first eaves portion;
a fourth eaves portion extending from the other end of the second body portion in the first direction toward the center of the electrode laminate in the surface direction and covering the second eaves portion; Item 5. A method for manufacturing an electric storage module according to Item 4. The fifth step further includes an eighth step of forming a third resin portion covering a third outer surface of the second resin portion,
5. The method of manufacturing an electric storage module according to claim 4, wherein said first resin portion is covered with said second resin portion and said third resin portion.

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