JP7063762B2 - Power storage module and manufacturing method of power storage module - Google Patents

Description

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

Conventionally, a so-called bipolar power storage module having a bipolar electrode having a negative electrode provided on one surface of an electrode plate and a positive electrode provided on the other surface is known (see Patent Document 1). In this method of manufacturing a power storage module, a sealing portion is heat-sealed on the peripheral edge of one surface of a bipolar electrode, the bipolar electrodes are laminated to form a battery laminate, and then the outermost periphery is heat-sealed.

Japanese Unexamined Patent Publication No. 2011-151016

When a seal portion made of resin is welded to the peripheral portion of a bipolar electrode, the electrode plate and the seal portion are formed after welding due to the difference between the shrinkage amount (shrinkage rate) of the electrode plate and the shrinkage amount (shrinkage rate) of the seal portion. May cause warping.

An object of the present invention is to provide a power storage module and a method for manufacturing a power storage module capable of reducing the amount of warpage of the electrode plate.

The power storage module according to one aspect of the present invention seals between an electrode laminate having a plurality of bipolar electrodes laminated via a separator and two bipolar electrodes adjacent to each other in the stacking direction of the plurality of bipolar electrodes. It is provided with a sealing body to be used. Each of the plurality of bipolar electrodes has an electrode plate, a first electrode provided on the first surface of the electrode plate, and a second electrode provided on the second surface opposite to the first surface of the electrode plate. Be prepared. The sealing body includes a primary sealing body provided on the outer edge portion of the electrode plate and a secondary sealing body provided around the primary sealing body. The primary sealing body includes a first resin layer provided on the first surface and a second resin layer provided on the second surface. The first resin layer extends inside the electrode laminate more than the second resin layer, and includes an extending region in which the outer edge portion of the separator is arranged.

In this power storage module, the primary sealant provided on the outer edge of the electrode plate is a first resin layer provided on the first surface of the electrode plate and a second resin layer provided on the second surface of the electrode plate. And. This primary encapsulant is formed, for example, by welding the first resin layer and the second resin layer to the electrode plate. The heat shrinkage rate of the first resin layer and the second resin layer is larger than the heat shrinkage rate of the electrode plate. Therefore, as the temperature of the outer edge portion of the electrode plate, the first resin layer, and the second resin layer decreases after welding, the first is caused by the difference between the heat shrinkage rate of the first resin layer and the heat shrinkage rate of the electrode plate. The outer edge portion of the surface is pulled by the first resin layer, and the outer edge portion of the second surface is pulled by the second resin layer due to the difference between the heat shrinkage rate of the second resin layer and the heat shrinkage rate of the electrode plate. However, the force received by the outer edge portion of the electrode plate from the first resin layer and the force received from the second resin layer act in a direction in which they cancel each other out. As a result, it is possible to reduce the amount of warpage of the electrode plate.

The region where the first resin layer on the first surface is provided may be roughened. The second resin layer may be composed of an acid-modified polyolefin resin. The acid-modified polyolefin resin can form a chemical bond with the outer edge of the electrode plate. Therefore, since it is not necessary to roughen the second surface, it is possible to facilitate the production of the electrode plate.

The region where the second resin layer on the second surface is provided may be roughened. The first resin layer may be composed of an acid-modified polyolefin resin. The acid-modified polyolefin resin can form a chemical bond with the outer edge of the electrode plate. Therefore, since it is not necessary to roughen the first surface, it is possible to facilitate the production of the electrode plate.

The first region where the first resin layer on the first surface is provided may be roughened. The second region where the second resin layer on the second surface is provided may be roughened. In this case, the types of resin materials that can be selected as the first resin layer and the second resin layer can be increased.

The method for manufacturing a power storage module according to another aspect of the present invention is provided on an electrode plate, a first electrode provided on the first surface of the electrode plate, and a second surface opposite to the first surface of the electrode plate. A step of preparing a plurality of bipolar electrodes each comprising a second electrode, a step of forming a primary sealant on the outer edge of each electrode plate of the plurality of bipolar electrodes, and a step of forming a plurality of bipolar electrodes via a separator. It is provided with a step of forming an electrode laminate by laminating the electrodes and a step of forming a secondary seal around the primary seal provided on the electrode laminate. In the step of forming the primary sealant, the first resin layer is arranged on the outer edge portion of the first surface, the second resin layer is arranged on the outer edge portion of the second surface, and the first resin layer and the second resin layer are arranged. Is welded to the electrode plate to form a primary encapsulant. The first resin layer includes an extending region extending inside the electrode laminate more than the second resin layer. In the step of forming the electrode laminate, the outer edge portion of the separator is arranged in the extending region.

In this method of manufacturing a power storage module, a first resin layer is arranged on the outer edge portion of the first surface of the electrode plate, a second resin layer is arranged on the outer edge portion of the second surface of the electrode plate, and the first resin layer and the first resin layer are arranged. 2 The resin layer is welded to the electrode plate to form a primary encapsulant. The heat shrinkage rate of the first resin layer and the second resin layer is larger than the heat shrinkage rate of the electrode plate. Therefore, as the temperature of the outer edge portion of the electrode plate, the first resin layer, and the second resin layer decreases after welding, the first is caused by the difference between the heat shrinkage rate of the first resin layer and the heat shrinkage rate of the electrode plate. The outer edge portion of the surface is pulled by the first resin layer, and the outer edge portion of the second surface is pulled by the second resin layer due to the difference between the heat shrinkage rate of the second resin layer and the heat shrinkage rate of the electrode plate. However, the force received by the outer edge portion of the electrode plate from the first resin layer and the force received from the second resin layer act in a direction in which they cancel each other out. As a result, it is possible to reduce the amount of warpage of the electrode plate.

According to the present invention, the amount of warpage of the electrode plate can be reduced.

FIG. 1 is a schematic cross-sectional view showing a power storage device including a power storage module according to an embodiment. FIG. 2 is a schematic cross-sectional view showing the internal configuration of the power storage module shown in FIG. FIG. 3 is an enlarged schematic view of a main part showing the configuration of the sealed body of the power storage module shown in FIG. FIG. 4 is a schematic cross-sectional view showing a bonding interface between the electrode plate included in the power storage module shown in FIG. 1 and the primary sealing body. FIG. 5 is a process diagram showing a main process of the method for manufacturing the power storage module shown in FIG. FIG. 6 is an enlarged schematic view of a main part showing the configuration of the sealed body of the power storage module according to the modified example.

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.

FIG. 1 is a schematic cross-sectional view showing a power storage device including a power storage module according to an embodiment. 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 laminate 2 and a restraint member 3.

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 plates 5. The power storage module 4 is a bipolar battery and has a rectangular shape when viewed from the stacking direction. The power storage module 4 is, for example, a secondary battery such as a nickel hydrogen secondary battery and a lithium ion secondary battery, or an electric double layer capacitor. In the following description, a nickel hydrogen secondary battery will be illustrated.

The two power storage modules 4 adjacent to each other in the stacking direction are electrically connected to each other via the conductive plate 5. The conductive plates 5 are arranged between two power storage modules 4 adjacent to each other in the stacking direction and outside the power storage modules 4 located at the stacking ends. A positive electrode terminal 6 is connected to a conductive plate 5 arranged outside the power storage module 4 located at the lower end of the stack. A negative electrode terminal 7 is connected to a conductive plate 5 arranged outside the power storage module 4 located at the upper end of the stack. The positive electrode terminal 6 and the negative electrode terminal 7 are drawn out from the edge of the conductive plate 5, for example, in a direction intersecting the stacking direction. The positive electrode terminal 6 and the negative electrode terminal 7 charge and discharge the power storage device 1.

Inside the conductive plate 5, a plurality of flow paths 5a through which a refrigerant such as air flows are provided. The flow path 5a extends along a direction intersecting (orthogonal) with, for example, the stacking direction and the drawing direction of the positive electrode terminal 6 and the negative electrode terminal 7. The conductive plate 5 has a function as a connecting member for electrically connecting two power storage modules 4 adjacent to each other in the stacking direction, and is generated by the power storage module 4 by circulating a refrigerant through these flow paths 5a. It also has a function as a heat sink that releases heat. In the example of FIG. 1, the area of the conductive plate 5 seen from the stacking direction is smaller than the area of the power storage module 4, but from the viewpoint of improving heat dissipation, the area of the conductive plate 5 is the area of the power storage module 4. It may be the same as, and may be larger than the area of the power storage module 4.

The restraint member 3 is a member that applies a restraint load to the module laminate 2 in the stacking direction of the module laminate 2. The restraint member 3 includes a pair of end plates 8 that sandwich the module laminate 2 in the stacking direction, and a fastening bolt 9 and a nut 10 that fasten the pair of end plates 8 to each other. The end plate 8 is a rectangular metal plate having an area one size larger than the area of the power storage module 4 and the conductive plate 5 when viewed from the stacking direction. A film F having electrical insulation is provided on the inner surface of the end plate 8. The film F insulates between the end plate 8 and the conductive plate 5.

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 plate 5 are sandwiched by the end plate 8 to be unitized as the module laminate 2, and a restraining load is applied to the module laminate 2 in the stacking direction.

Next, the configuration of the power storage module 4 will be described in detail. FIG. 2 is a schematic cross-sectional view showing the internal configuration of the power storage module shown in FIG. As shown in FIG. 2, the power storage module 4 includes an electrode laminated body 11 and a sealing body 12 that seals the electrode laminated body 11. The electrode laminate 11 has a plurality of separators 13, a plurality of bipolar electrodes 14, a negative electrode termination electrode 18, and a positive electrode termination electrode 19. In the present embodiment, the stacking direction D of the electrode laminated body 11 coincides with the stacking direction of the module laminated body 2. The electrode laminate 11 has a side surface 11a extending in the stacking direction D.

The separator 13 is formed, for example, in the form of a sheet. Examples of the separator 13 include a porous film made of a polyolefin resin such as polyethylene (PE) and polypropylene (PP), and a woven fabric or a non-woven fabric made of polypropylene and methyl cellulose. The separator 13 may be reinforced with a vinylidene fluoride resin compound. The separator 13 may be in the shape of a bag.

The negative electrode termination electrode 18, the plurality of bipolar electrodes 14, and the positive electrode termination electrode 19 are laminated in this order via the separator 13. Each of the plurality of bipolar electrodes 14 includes an electrode plate 15, a positive electrode 16 (first electrode), and a negative electrode 17 (second electrode). The electrode plate 15 is made of, for example, a metal foil made of nickel or a nickel-plated steel plate, and has a rectangular shape. The electrode plate 15 includes an upper surface 15a (first surface) and a lower surface 15b (second surface) opposite to the upper surface 15a. The outer edge portion 15c of the electrode plate 15 is an uncoated area in which the positive electrode active material and the negative electrode active material are not coated.

The positive electrode 16 is provided on the upper surface 15a of the electrode plate 15. The positive electrode 16 is a positive electrode active material layer formed by applying a positive electrode active material to the upper surface 15a. Examples of the positive electrode active material constituting the positive electrode 16 include nickel hydroxide. The negative electrode 17 is provided on the lower surface 15b of the electrode plate 15. The negative electrode 17 is a negative electrode active material layer formed by applying a negative electrode active material to the lower surface 15b. 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 lower surface 15b of the electrode plate 15 is one size larger than the formation region of the positive electrode 16 on the upper surface 15a of the electrode plate 15.

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.

The negative electrode terminal electrode 18 is arranged at one end of the electrode laminate 11 in the stacking direction D. The negative electrode terminal electrode 18 includes an electrode plate 15 and a negative electrode 17 provided on the lower surface 15b of the electrode plate 15. The negative electrode 17 of the negative electrode terminal electrode 18 faces the positive electrode 16 of the bipolar electrode 14 located at one end in the stacking direction D via the separator 13. One of the conductive plates 5 adjacent to the power storage module 4 is in contact with the upper surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18.

The positive electrode terminal electrode 19 is arranged at the other end of the electrode laminate 11 in the stacking direction D. The positive electrode terminal electrode 19 includes an electrode plate 15 and a positive electrode 16 provided on the upper surface 15a of the electrode plate 15. The positive electrode 16 of the positive electrode terminal electrode 19 faces the negative electrode 17 of the bipolar electrode 14 located at the other end of the stacking direction D via the separator 13. The other conductive plate 5 adjacent to the power storage module 4 is in contact with the lower surface 15b of the electrode plate 15 of the positive electrode terminal electrode 19.

FIG. 3 is an enlarged schematic view of a main part showing the configuration of the sealed body of the power storage module shown in FIG. The sealing body 12 shown in FIGS. 2 and 3 is formed, for example, in the shape of a rectangular cylinder. The sealing body 12 is formed of an insulating resin material. Examples of the resin material constituting the sealing body 12 include polypropylene (PP), polyphenylene sulfide (PPS), modified polyphenylene ether (modified PPE), and the like. As the resin material constituting the sealing body 12, an acid-modified polyolefin resin such as acid-modified polypropylene may be used. The sealing body 12 is configured to hold the outer edge portion 15c of the electrode plate 15 on the side surface 11a of the electrode laminated body 11 extending in the stacking direction D and to surround the side surface 11a. The sealing body 12 seals between two bipolar electrodes 14 adjacent to each other in the stacking direction D.

The sealing body 12 has a plurality of primary sealing bodies 21A, a primary sealing body 21B, a primary sealing body 21C, and a secondary sealing body 22. The primary sealants 21A, 21B, and 21C are continuously provided on the outer edge portion 15c (uncoated region) of the electrode plate 15 over the entire circumference (all sides) of the electrode plate 15. The primary sealants 21A, 21B, 21C have an inner edge portion 21a and an outer edge portion 21b. The inner edge portion 21a overlaps with the electrode plate 15 when viewed from the stacking direction D. The outer edge portion 21b projects to the outside of the electrode plate 15 when viewed from the stacking direction D. At least a part of the inner edge portion 21a is airtightly bonded to the outer edge portion 15c of the electrode plate 15. The end faces of the primary sealing bodies 21A, 21B, 21C on the outer edge portion 21b side are airtightly joined to the inner surface 22a of the secondary sealing body 22.

Each of the plurality of primary sealants 21A is provided on the outer edge portion 15c of the electrode plate 15 constituting the bipolar electrode 14. The primary sealant 21A has a resin layer 23 (first resin layer) and a resin layer 24 (second resin layer). The resin layer 23 is provided on the outer edge portion 15d (first region) of the upper surface 15a. The resin layer 23 is bonded (welded) to the outer edge portion 15d of the upper surface 15a by heat, for example. The resin layer 24 is provided on the outer edge portion 15e (second region) of the lower surface 15b. The resin layer 24 is bonded (welded) to the outer edge portion 15e of the lower surface 15b by heat, for example. The joining of the resin layer 23 and the joining of the resin layer 24 are performed at the same time, for example, by hot pressing. The outer edge 23a of the resin layer 23 coincides with the outer edge 24a of the resin layer 24 when viewed from the stacking direction D. The inner edge 23b of the resin layer 23 is located inside the electrode laminate 11 with respect to the inner edge 24b of the resin layer 24 when viewed from the stacking direction D.

In the electrode laminate 11, the resin layer 23 provided on the upper surface 15a of one electrode plate 15 is in contact with the resin layer 24 provided on the lower surface 15b of the electrode plates 15 adjacent to each other in the stacking direction D. That is, the resin layer 23 includes an extending region 23c extending inside the electrode laminate 11 rather than the adjacent resin layer 24, and a covering region 23d covered with the resin layer 24. The outer edge portion 13a of the separator 13 is arranged (placed) in the extending region 23c. The two electrode plates 15 adjacent to each other in the stacking direction D are kept in a state of being insulated from each other by the separator 13 and the primary sealants 21A, 21B, 21C.

The covering region 23d is arranged outside the extending region 23c. Seen from the stacking direction D, the outer edge of the separator 13 is located between the inner edge 23b of the resin layer 23 and the inner edge 24b of the resin layer 24. The inner edge of the covering region 23d (inner edge 24b of the resin layer 24) is located inside the electrode laminate 11 with respect to the outer edge of the electrode plate 15 when viewed from the stacking direction D. The entire extending region 23c, a part of the covering region 23d, and a part of the resin layer 24 form an inner edge portion 21a. The remaining portion of the covering region 23d and the remaining portion of the resin layer 24 constitute the outer edge portion 21b. The resin layer 23 provided on the upper surface 15a of one electrode plate 15 and the resin layer 24 provided on the lower surface 15b of the electrode plates 15 adjacent to each other in the stacking direction D may be separated from each other.

The primary sealant 21B is provided on the outer edge portion 15c of the electrode plate 15 constituting the negative electrode terminal electrode 18. The primary sealant 21B is mainly different from the primary sealant 21A in that it has the resin layer 25 instead of the resin layer 23. The resin layer 25 has the same structure as the resin layer 23 except that the thickness of the resin layer 25 is larger than that of the resin layer 23. The primary sealant 21C is provided on the outer edge portion 15c of the electrode plate 15 constituting the positive electrode terminal electrode 19. The primary sealant 21C is mainly different from the primary sealant 21A in that it has the resin layer 26 instead of the resin layer 24. The resin layer 26 is thicker than the resin layer 24 and extends inside the electrode laminate 11 more than the resin layer 24. That is, when viewed from the stacking direction D, the inner edge 23b of the resin layer 23 coincides with the inner edge of the resin layer 26.

FIG. 4 is a schematic cross-sectional view showing a bonding interface between the electrode plate included in the power storage module shown in FIG. 1 and the primary sealing body. As shown in FIG. 4, the upper surface 15a (outer edge portion 15d) of the electrode plate 15 is roughened. The lower surface 15b (outer edge portion 15e) of the electrode plate 15 is also roughened. For example, by electroplating the upper surface 15a and the lower surface 15b, a plurality of fine protrusions 15p are formed on the upper surface 15a and the lower surface 15b, whereby the upper surface 15a and the lower surface 15b are roughened. The protrusion 15p has, for example, a shape that becomes thicker from the base end of the protrusion 15p toward the tip of the protrusion 15p. In this case, the cross-sectional shape between the two protrusions 15p adjacent to each other is an undercut shape, and the anchor effect is likely to occur. Note that FIG. 4 is a schematic diagram, and the shape and density of the protrusions 15p are not particularly limited. The thickness t1 of the resin layer 23 and the thickness t2 of the resin layer 24 are much larger than the height h (length in the stacking direction D) of the protrusions 15p.

In the present embodiment, the entire upper surface 15a and lower surface 15b of the electrode plate 15 are roughened. Only the outer edge portion 15d on the upper surface 15a may be roughened, or only the outer edge portion 15e on the lower surface 15b may be roughened. That is, it is sufficient that at least the joint portion of the upper surface 15a with the resin layer 23 is roughened. Similarly, of the lower surface 15b, at least the joint portion with the resin layer 24 may be roughened. At the junction interface between the electrode plate 15 and the primary encapsulant 21A, the molten primary encapsulant 21A enters the recesses (between two adjacent projections 15p) formed by roughening, and the anchor effect is exhibited. Will be done. As a result, in the bipolar electrode 14, the bonding force and the liquidtightness between the electrode plate 15 and the primary sealing body 21A are improved.

In the present embodiment, the upper surface 15a and the lower surface 15b of the electrode plate 15 in the negative electrode terminal 18 and the positive electrode 19 are also roughened. As a result, in the negative electrode terminal electrode 18, the bonding force between the electrode plate 15 and the primary sealing body 21B is improved. In the positive electrode terminal electrode 19, the bonding force between the electrode plate 15 and the primary sealing body 21C is improved.

The secondary sealing body 22 is provided so as to surround the group of the primary sealing bodies 21A, 21B, 21C from the outside. The secondary encapsulant 22 is provided around the electrode laminate 11 and the primary encapsulants 21A, 21B, 21C, and constitutes the outer wall (housing) of the power storage module 4. The secondary sealing body 22 is formed, for example, by injection molding of a resin, and extends along the stacking direction D over the entire length of the electrode laminated body 11. The secondary encapsulant 22 has a tubular shape (annular shape) extending with the stacking direction D as the axial direction. The secondary encapsulant 22 is welded (bonded) to the end faces of the primary encapsulants 21A, 21B, 21C on the outer edge portion 21b side by heat during injection molding, for example.

The secondary encapsulant 22, together with the primary encapsulants 21A, 21B, 21C, is between two bipolar electrodes 14 adjacent to each other along the stacking direction D, and a negative electrode termination electrode 18 adjacent to each other along the stacking direction D. The space between the bipolar electrode 14 and the space between the positive electrode terminal 19 and the bipolar electrode 14 adjacent to each other along the stacking direction D are sealed. As a result, an airtightly partitioned internal space V is formed between the two bipolar electrodes 14, between the negative electrode terminal 18 and the bipolar electrode 14, and between the positive electrode terminal 19 and the bipolar electrode 14. Has been done. Each internal space V contains an electrolytic solution (not shown) composed of an alkaline aqueous solution such as a potassium hydroxide aqueous solution. The electrolytic solution is impregnated in the separator 13, the positive electrode 16 and the negative electrode 17.

Next, a method of manufacturing the power storage module 4 will be described. FIG. 5 is a process diagram showing a main process of the method for manufacturing the power storage module shown in FIG. As shown in FIG. 5, first, a preparation step S1 for preparing a plurality of bipolar electrodes 14, a negative electrode termination electrode 18, and a positive electrode termination electrode 19 is performed.

Subsequently, the primary molding step S2 for forming the primary sealing body 21A on the outer edge portion 15c of the electrode plate 15 of each bipolar electrode 14 is performed. In the primary molding step S2, the resin layer 23 is arranged on the outer edge portion 15d of the upper surface 15a, and the resin layer 24 is arranged on the outer edge portion 15e of the lower surface 15b. Then, the heat pressing is performed so as to sandwich the resin layer 23 and the resin layer 24. As a result, the resin layer 23 and the resin layer 24 are welded to the electrode plate 15 to form the primary sealing body 21A. The primary encapsulants 21B and 21C are formed in the same manner for the negative electrode terminal 18 and the positive electrode 19.

Subsequently, the laminating step S3 for forming the electrode laminate 11 is performed by laminating the negative electrode termination electrode 18, the plurality of bipolar electrodes 14, and the positive electrode termination electrode 19 via the separator 13. In the laminating step S3, the outer edge portion 13a of the separator 13 is arranged in the extending region 23c of the resin layer 23. Further, the resin layer 24 formed on the other electrode plate 15 is stacked on the covering region 23d of the resin layer 23 formed on one electrode plate 15.

Subsequently, the secondary molding step S4 for forming the secondary sealing body 22 around the primary sealing body 21 provided on the electrode laminated body 11 is performed. In the secondary molding step S4, the electrode laminate 11 is sandwiched in the stacking direction D by a pair of molding dies, and a resin material is poured into the cavity in the molding die with a restraining load applied to the electrode laminate 11. The next sealing body 22 is formed. As a result, the power storage module 4 is obtained.

In the method of manufacturing the power storage module 4 and the power storage module 4 described above, the resin layer 23 is arranged on the outer edge portion 15d of the upper surface 15a of the electrode plate 15, and the resin layer 24 is arranged on the outer edge portion 15e of the lower surface 15b of the electrode plate 15. The resin layer 23 and the resin layer 24 are welded to the electrode plate 15 to form the primary sealing body 21. The heat shrinkage of the resin layer 23 and the resin layer 24 is larger than the heat shrinkage of the electrode plate 15. Therefore, as the temperature of the outer edge portion 15c of the electrode plate 15, the resin layer 23, and the resin layer 24 decreases after welding, the upper surface 15a is caused by the difference between the heat shrinkage rate of the resin layer 23 and the heat shrinkage rate of the electrode plate 15. The outer edge portion 15d of the lower surface 15b is pulled by the resin layer 23, and the outer edge portion 15e of the lower surface 15b is pulled by the resin layer 24 due to the difference between the heat shrinkage rate of the resin layer 24 and the heat shrinkage rate of the electrode plate 15. However, the force received from the resin layer 23 and the force received from the resin layer 24 by the outer edge portion 15c of the electrode plate 15 act in a direction in which they cancel each other out. As a result, it is possible to reduce the amount of warpage of the electrode plate 15. Therefore, since the stacking of the plurality of bipolar electrodes 14 can be facilitated, the quality of the power storage module 4 can be improved, and the yield of the power storage module 4 can be improved.

Further, in the secondary molding step S4, the outer edge portion 13a of the separator 13 is arranged in the extending region 23c. When the secondary sealing body 22 is formed by injection molding, the inner edge portions 21a of the primary sealing bodies 21A, 21B, 21C and the outer edge portion 15c of the electrode plate 15 are sandwiched in the stacking direction D by a pair of molding dies. At this time, since the outer edge portion 13a of the separator 13 is not sandwiched between the pair of molding dies, the restraining load is uniformly applied to the inner edge portions 21a of the primary sealing bodies 21A, 21B, 21C and the outer edge portion 15c of the electrode plate 15. Can be done. This makes it possible to reduce the formation defects of the secondary sealing body 22.

The outer edge portion 15d and the outer edge portion 15e are roughened. As a result, the bonding force and the liquidtightness between the electrode plate 15 and the primary sealing body 21A (resin layer 23 and resin layer 24) are improved. Therefore, as the resin layer 23 and the resin layer 24, not only the resin material having high adhesiveness to the metal material constituting the electrode plate 15 but also other resin materials can be selected. Therefore, the types of resin materials that can be selected as the resin layer 23 and the resin layer 24 can be increased.

Although the 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 inner edge 23b of the resin layer 23 is located inside the electrode laminate 11 with respect to the inner edge 24b of the resin layer 24 when viewed from the stacking direction D. However, as shown in FIG. 6, when viewed from the stacking direction D, the inner edge 23b of the resin layer 23 (second resin layer) is outside the electrode laminate 11 than the inner edge 24b of the resin layer 24 (first resin layer). It may be located in. That is, the resin layer 24 may include an extending region 24c extending inside the electrode laminate 11 rather than the adjacent resin layer 23, and a covering region 24d covered with the resin layer 23. In this case, the outer edge portion 13a of the separator 13 is arranged (placed) in the extending region 24c. The covering region 24d is arranged outside the extending region 24c.

When the resin layer 23 is composed of an acid-modified polyolefin resin, the acid-modified polyolefin resin has an acid group in its molecule. Therefore, at the junction between the resin layer 23 and the outer edge portion 15d, the acid group in the resin layer 23 A chemical bond may be formed between the resin and the hydroxyl group of the outer edge portion 15d of the electrode plate 15. Therefore, the upper surface 15a (outer edge portion 15d) may be a flat surface that has not been roughened. As a result, it is not necessary to roughen the upper surface 15a, so that the production of the electrode plate 15 can be facilitated.

Similarly, when the resin layer 24 is made of an acid-modified polyolefin resin, the acid group in the resin layer 24 and the hydroxyl group of the outer edge portion 15e of the electrode plate 15 are formed at the joint portion between the resin layer 24 and the outer edge portion 15e. Chemical bonds can be formed between them. Therefore, the lower surface 15b (outer edge portion 15e) may be a flat surface that has not been roughened. As a result, it is not necessary to roughen the lower surface 15b, so that the production of the electrode plate 15 can be facilitated.

The chemical bond between the acid-modified polyolefin resin and the electrode plate 15 can be broken by the electrolytic solution contained in the internal space V. In the power storage device 1, at least one of the bonding between the upper surface 15a and the resin layer 23 and the bonding between the lower surface 15b and the resin layer 24 in order to insulate and separate the two internal spaces V adjacent to each other. Is desired to be maintained. At least one of the upper surface 15a and the lower surface 15b (specifically, the outer edge portion 15d and the outer edge portion 15e) is roughened in order to maintain the joint. That is, the upper surface 15a (outer edge portion 15d) may be roughened, and the lower surface 15b (outer edge portion 15e) may be a flat surface that has not been roughened. Alternatively, the lower surface 15b (outer edge portion 15e) may be roughened, and the upper surface 15a (outer edge portion 15d) may be a flat surface that has not been roughened.

4 ... Energy storage module, 11 ... Electrode laminate, 12 ... Sealed body, 13 ... Separator, 13a ... Outer edge, 14 ... Bipolar electrode, 15 ... Electrode plate, 15a ... Top surface (first surface), 15b ... Bottom surface (No. 1) 2 surfaces), 15c ... outer edge portion, 15d ... outer edge portion (first region), 15e ... outer edge portion (second region), 16 ... positive electrode (first electrode), 17 ... negative electrode (second electrode), 21A ... primary Encapsulant, 22 ... Secondary encapsulant, 23 ... Resin layer, 23c, 24c ... Extension region, 24 ... Resin layer, D ... Lamination direction.

Claims (5)

An electrode laminate having a plurality of bipolar electrodes laminated via a separator, and
A sealant that seals between two bipolar electrodes adjacent to each other in the stacking direction of the plurality of bipolar electrodes.
Equipped with
Each of the plurality of bipolar electrodes is provided on an electrode plate, a first electrode provided on the first surface of the electrode plate, and a second surface of the electrode plate opposite to the first surface. With electrodes,
The sealing body includes a primary sealing body provided on the outer edge portion of the electrode plate and a secondary sealing body provided around the primary sealing body.
The primary sealant includes a first resin layer welded to the first surface and a second resin layer welded to the second surface.
The first resin layer extends inside the electrode laminate more than the second resin layer, and includes an extending region on which the outer edge portion of the separator is placed .
At least one of the first joint portion with the first resin layer on the first surface and the second joint portion with the second resin layer on the second surface is a roughened storage module. .. The first joint portion is roughened and has a roughened surface.
The power storage module according to claim 1, wherein the second resin layer is made of an acid-modified polyolefin resin. The second joint portion is roughened and has a roughened surface.
The power storage module according to claim 1, wherein the first resin layer is made of an acid-modified polyolefin resin. The first joint portion is roughened and has a roughened surface.
The power storage module according to claim 1, wherein the second joint portion is roughened. A plurality of bipolar electrodes including an electrode plate, a first electrode provided on the first surface of the electrode plate, and a second electrode provided on a second surface of the electrode plate opposite to the first surface. The process of preparing the electrodes and
A step of forming a primary sealant on the outer edge of the electrode plate of each of the plurality of bipolar electrodes, and
A step of forming an electrode laminate by laminating the plurality of bipolar electrodes via a separator, and
A step of forming a secondary encapsulation body around the primary encapsulation body provided on the electrode laminate, and a step of forming the secondary encapsulation body.
Equipped with
In the step of forming the primary encapsulation body, the first resin layer is arranged on the outer edge portion of the first surface, and the second resin layer is arranged on the outer edge portion of the second surface. By welding the second resin layer to the electrode plate, the primary encapsulant is formed.
The first resin layer includes an extending region extending inside the electrode laminate more than the second resin layer.
A method for manufacturing a power storage module in which an outer edge portion of the separator is placed in the extending region in the step of forming the electrode laminate.

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