JP6977333B2 - Power storage device and manufacturing method of power storage device - Google Patents

Description

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

As a conventional power storage device, a bipolar battery including a bipolar electrode having a positive electrode formed on one surface of an electrode plate and a negative electrode formed on the other surface is known (see Patent Document 1). The bipolar battery includes a laminate formed by laminating a plurality of bipolar electrodes via a separator. The laminated body is provided with a sealing body made of resin for sealing, and the edge portion of the electrode plate is held on the side surface formed by laminating the bipolar electrodes.

Japanese Unexamined Patent Publication No. 2011-204386

As a method for manufacturing a power storage device as described above, for example, a part of the encapsulant is formed in advance on the edge of each electrode plate, and the part is located between the edges of the electrode plates. After laminating the bipolar electrode on the surface, a method of forming the rest of the sealed body so as to surround the part from the outside can be considered. However, in such a case, when a part of the sealing body is welded to the edge of the electrode plate, the expansion amount of the part becomes larger than the expansion amount of the electrode plate, so that the electrode plate is wrinkled or warped. There is concern about doing so. Wrinkles and warpage of the electrode plates may induce a short circuit between adjacent electrode plates. Further, the power storage device as described above, suppression of the displacement of the separator at the time of lamination of the bipolar electrode is obtained.

The present invention has been made in order to solve the above problems, the suppression of wrinkle or warp of the electrode plate, to provide a method for producing及beauty power storage device and the power storage device positional deviation of inhibition was achieved in the separator With the goal.

The power storage device according to one aspect of the present invention is a power storage device having a bipolar electrode composed of an electrode plate having a positive electrode formed on one side and a negative electrode formed on the other side, and the bipolar electrode is interposed via a separator. The laminated body is provided with a laminated body and a resin encapsulant provided on the side surface of the laminated body so as to surround the edge of the bipolar electrode, and the encapsulant is at least between the edges of the electrode plates. It has a first portion arranged between them and a second portion that surrounds the first portion from the outside along the side surface. The separator is made of a non-woven fabric, and the laminate has a separator as the first portion. It is configured by laminating an electrode unit formed by being coupled to a bipolar electrode via an electrode.

In this power storage device, the separator is made of a non-woven fabric, and the laminated body is formed by laminating an electrode unit in which the separator is coupled to a bipolar electrode via a first portion of a sealed body. The electrode unit is formed, for example, by melting and solidifying the resin member in a state where the resin member and the non-woven fabric are stacked on the edge of the electrode plate in this order. At this time, since the coefficient of thermal expansion of the non-woven fabric is smaller than the coefficient of thermal expansion of the resin member, the non-woven fabric can suppress the thermal expansion of the first portion (resin member). As a result, the difference between the expansion amount of the first portion and the expansion amount of the electrode plate can be reduced, and the occurrence of wrinkles and warpage of the electrode plate can be suppressed . Further, since the laminate is formed by laminating the electrode unit and the separator and the bipolar electrode are integrated, it is also possible to suppress the positional displacement between the separator and the bipolar electrode.

Also, the separator may have a thermal history in which heating up to the melting temperature of the first portion is considered once. In this case, since the coefficient of thermal expansion of the nonwoven fabric is the smallest at the time of the first heating, the thermal expansion of the first portion can be effectively suppressed.

Further, the outer edge of the separator may be located outside the outer edge of the electrode plate when viewed from the stacking direction of the laminated body. In this case, a bonding region between the separator and the first portion can be secured, and the separator and the first portion can be reliably bonded.

Further, the outer edge of the separator may be located inside the outer edge of the electrode plate when viewed from the stacking direction of the laminated body. In this case, the electrode unit can be miniaturized.

The method for manufacturing a power storage device according to one aspect of the present invention is a laminated body in which a bipolar electrode made of an electrode plate having a positive electrode formed on one side and a negative electrode formed on the other side is laminated via a separator. , A method of manufacturing a power storage device including a resin encapsulation body provided on the side surface of the laminated body so as to surround the edge of the bipolar electrode, wherein the resin member and the non-woven electrode are placed on the edge of the electrode plate. A primary molding step of forming a plurality of electrode units in which a separator is coupled to a bipolar electrode via a first portion of a sealed body by melting and solidifying the resin members in a state of being stacked in this order, and an electrode. A laminating step of forming a laminated body by laminating the units, and a secondary molding step of forming a second portion of the sealed body that surrounds the first portion from the outside along the side surface of the laminated body. include.

In this method of manufacturing a power storage device, a resin member and a non-woven fabric are laminated on the edge of an electrode plate in this order, and the resin member is melted and solidified so that a separator is interposed through a first portion of a sealed body. To form an electrode unit coupled to a bipolar electrode. At this time, since the coefficient of thermal expansion of the non-woven fabric is smaller than the coefficient of thermal expansion of the resin member, the non-woven fabric can suppress the thermal expansion of the first portion (resin member). As a result, the difference between the expansion amount of the first portion and the expansion amount of the electrode plate can be reduced, and the occurrence of wrinkles and warpage of the electrode plate can be suppressed . Further, since forming a laminate by laminating the electrode unit and the separator and the bipolar electrode are integrated, it is also possible to suppress the positional displacement between the separator and the bipolar electrode.

According to the present invention, suppression of wrinkle or warp of the electrode plate can provide a method for producing及beauty positional deviation inhibition achieved power storage device and power storage device separator.

It is a schematic sectional drawing which shows one Embodiment of a power storage device. It is a schematic sectional drawing which shows the internal structure of the power storage module of FIG. (A) and (b) are schematic cross-sectional views showing the manufacturing method of the power storage device of FIG. It is a graph which shows an example of the change of the elongation amount of a nonwoven fabric by the number of times of heating. (A) and (b) are schematic cross-sectional views showing the first modification example and the second modification example. It is a schematic sectional view of a part.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals will be used for the same or equivalent elements, and duplicate description will be omitted.

FIG. 1 is a schematic cross-sectional view showing an embodiment of a power storage device. The power storage device 1 shown in the figure is used as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 is configured to include a power storage module stack 2 formed by stacking a plurality of power storage modules 4, and a restraint member 3 that applies a restraint load to the power storage module stack 2 in the stacking direction.

The power storage module stack 2 is composed of a plurality of (three in this embodiment) power storage modules 4 and a plurality of conductive plates 5 arranged between the power storage modules 4 and 4. The power storage module 4 is, for example, a bipolar battery provided with a bipolar electrode 14 described later, 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 or a lithium ion secondary battery, or an electric double layer capacitor. In the following description, a nickel-metal hydride secondary battery will be illustrated.

The storage modules 4 and 4 adjacent to each other in the stacking direction are electrically connected to each other via the conductive plate 5. The conductive plate 5 is also arranged on the outside of the power storage module 4 located at the laminated end. A positive electrode terminal 6 is connected to one of the conductive plates 5 arranged outside the power storage module 4 located at the laminated end. The negative electrode terminal 7 is connected to the other conductive plate 5 arranged outside the power storage module 4 located at the laminated end. 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 with each other in the stacking direction. The positive electrode terminal 6 and the negative electrode terminal 7 charge and discharge the power storage device 1.

Inside each conductive plate 5, a plurality of flow paths 5a through which a refrigerant such as air flows are provided. Each flow path 5a extends in parallel with each other, for example, in a direction orthogonal to the stacking direction and the drawing direction of the positive electrode terminal 6 and the negative electrode terminal 7. By circulating the refrigerant through these flow paths 5a, the conductive plate 5 not only functions as a connecting member for electrically connecting the storage modules 4 and 4 to each other, but also a heat radiating plate that dissipates heat generated by the storage module 4. It also has the function of. 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 composed of a pair of end plates 8 and 8 that sandwich the power storage module laminate 2 in the stacking direction, and a fastening bolt 9 and a nut 10 that fasten the end plates 8 and 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 side surface of the end plate 8 (the surface on the side of the storage module laminate 2). 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 power storage module laminated body 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 plates 8 and 8 to be unitized as the power storage module stack 2, and a restraining load is applied to the power storage module stack 2 in the stacking direction.

Next, the configuration of the power storage module 4 will be described in more detail. FIG. 2 is a schematic cross-sectional view showing the internal configuration of the power storage module 4. As shown in the figure, the power storage module 4 includes an electrode laminate 11 and a sealing body 12 that seals the electrode laminate 11.

The electrode laminate 11 has a structure in which a plurality of bipolar electrodes 14 are laminated via a separator 13. The bipolar electrode 14 is an electrode made of an electrode plate 15 having a positive electrode 16 formed on one surface 15a and a negative electrode 17 formed on the other surface 15b. In the electrode laminate 11, the positive electrode 16 of one bipolar electrode 14 faces the negative electrode 17 of one of the bipolar electrodes 14 adjacent to each other in the stacking direction 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 with the separator 13 interposed therebetween.

The negative electrode terminal electrode 18 is arranged on one of the laminated ends of the electrode laminated body 11, and the positive electrode terminal electrode 19 is arranged on the other side of the laminated end of the electrode laminated body 11. The negative electrode terminal electrode 18 is an electrode plate 15 having a negative electrode 17 formed on an inner surface (a surface on the center side in the stacking direction), and the positive electrode terminal electrode 19 is a positive electrode 16 on an inner surface (a surface on the center side in the stacking direction). Is the electrode plate 15 on which the is formed. The negative electrode 17 of the negative electrode terminal electrode 18 faces the positive electrode 16 of one of the bipolar electrodes 14 at the laminated end via the separator 13. The positive electrode 16 of the positive electrode terminal electrode 19 faces the negative electrode 17 of the other bipolar electrode 14 at the laminated end via the separator 13. The electrode plate 15 of the negative electrode terminal 18 and the electrode plate 15 of the positive electrode 19 are electrically connected to the conductive plate 5 (see FIG. 1) adjacent to the power storage module 4.

The electrode plate 15 is a rectangular metal leaf made of, for example, nickel. The edge portion (edge portion of the bipolar electrode 14) 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. Examples of the positive electrode active material constituting the positive electrode 16 include nickel hydroxide. Examples of the negative electrode active material constituting the negative electrode 17 include a hydrogen storage alloy. In the present embodiment, the formation region of the negative electrode 17 on the other surface 15b of the electrode plate 15 is slightly larger than the formation region of the positive electrode 16 on the one surface 15a of the electrode plate 15.

The separator 13 is made of, for example, a rectangular non-woven fabric having the same planar shape as the electrode plate 15. Examples of the non-woven fabric constituting the separator 13 include non-woven fabrics in which fibers are bonded to each other by fusion, adhesion, entanglement, or the like. The separator 13 is composed of fibers made of, for example, polyamide (PA), but may be made of fibers made of polyphenylene sulfide (PPS), polyolefin, or the like. As will be described later, the separator 13 has a thermal history in which the first portion 21 of the sealing body 12 is heated to the melting temperature only once.

The sealing body 12 is formed in a rectangular tubular shape, for example, by an insulating resin. Examples of the resin material constituting the sealing body 12 include polypropylene (PP), polyphenylene sulfide (PPS), modified polyphenylene ether (modified PPE), and the like. The sealing body 12 is configured to surround the side surface 11a of the electrode laminated body 11 formed by laminating the bipolar electrodes 14.

The sealing body 12 includes a first portion 21 provided along the edge portion 15c of the electrode plate 15 of each bipolar electrode 14, and a second portion provided so as to surround the entire first portion 21 from the outside. It is composed of 22 and. The first portion 21 is continuously provided over all sides of the electrode plate 15 at the edge portion 15c (uncoated region) on the one side 15a side of the electrode plate 15. The first portion 21 is bonded to the edge portion 15c by welding. A part of the inside of the first portion 21 is located between the edges 15c of the electrode plates 15 of the bipolar electrodes 14 and 14 adjacent to each other in the stacking direction, and a part of the outside is outside from the electrode plate 15. Overhanging. The first portion 21 is buried in the second portion 22 in the outer part thereof.

The second portion 22 is formed, for example, by injection molding of a resin, and extends over the entire length of the electrode laminate 11 in the stacking direction. The second portion 22 is welded to the outer surface of the first portion 21 by heat during injection molding, for example, and seals between the bipolar electrodes 14 and 14 adjacent to each other in the stacking direction. As a result, an internal space V is formed between the bipolar electrodes 14 and 14 adjacent to each other in the stacking direction. The internal space V contains an electrolytic solution (not shown) composed of an alkaline solution such as an aqueous potassium hydroxide solution.

Here, in the electrode laminate 11 of the present embodiment, the edge portion 13a of the separator 13 is welded to the surface 21a on the opposite side of the electrode plate 15 of the first portion 21. As a result, the electrode unit 20 in which the separator 13 and the bipolar electrode 14 are integrated with each other is configured. The electrode laminated body 11 is configured by laminating a plurality of the electrode units 20. In this example, the outer edges of the separator 13 and the electrode plate 15 coincide with each other when viewed from the stacking direction of the electrode laminate 11.

Subsequently, the manufacturing method of the power storage device 1 described above will be described. The manufacturing method of the power storage device 1 according to the present embodiment includes a primary molding step, a laminating step, and a secondary molding step.

In the primary molding step, the bipolar electrode 14 is prepared, and as shown in FIG. 3A, the resin member 41 and the nonwoven fabric 42 are placed on the edge portion 15c of the electrode plate 15 in this order. The resin member 41 and the nonwoven fabric 42 are members corresponding to the above-mentioned first portion 21 and separator 13, respectively. Subsequently, in that state, the electrode plate 15, the resin member 41, and the nonwoven fabric 42 are hot-pressed in the laminating direction to heat them to a predetermined welding temperature to melt and solidify the resin member 41. As a result, the resin member 41 and the nonwoven fabric 42 become the first portion 21 and the separator 13 described above, respectively, and the separator unit 20 is formed by coupling the separator 13 to the bipolar electrode 14 via the first portion 21. In the primary molding step, a predetermined number of the electrode units 20 are formed.

Here, the welding temperature is set to a temperature higher than the melting temperature of the resin member 41 (first portion 21). The welding temperature is set to, for example, about 200 ° C. The melting temperature of the nonwoven fabric 42 is higher than the welding temperature, and the nonwoven fabric 42 does not melt during the primary molding process.

Further, in the primary molding step, the nonwoven fabric 42 that has never been heated to the melting temperature of the resin member 41 in the past is used. That is, in the primary molding step, the resin member 41 and the nonwoven fabric 42 are welded in a state where the nonwoven fabric 42 that has never been heated to the melting temperature of the resin member 41 has been laminated on the resin member 41 in the past. Heat to temperature. As a result, in the power storage device 1, the separator 13 has a heat history in which heating up to the melting temperature of the first portion 21 is performed only once.

In the laminating step, as shown in FIG. 3B, the electrode laminated body 11 is formed by laminating a plurality of electrode units 20. In the secondary molding step, after the electrode laminate 11 is placed in the injection molding die (not shown), the molten resin is injected into the die to surround the first portion 21 with the second portion. 22 is formed. As a result, the sealing body 12 is formed on the side surface 11a of the electrode laminated body 11.

After the secondary molding step, a step of injecting an electrolytic solution into the internal space V between the bipolar electrodes 14 and 14, a step of laminating the power storage module 4 and the conductive plate 5 to form the power storage module laminate 2, and a restraint member. The power storage device 1 shown in FIG. 1 is obtained through a step of restraining the power storage module stack 2 by 3.

Subsequently, the operation and effect of the power storage device 1 will be described.

In the power storage device 1, the separator 13 is made of a non-woven fabric 42, and the separator 13 is laminated to the bipolar electrode 14 via the first portion 21 of the sealing body 12 by laminating the electrode unit 20. The body 11 is configured. The electrode unit 20 is formed by, for example, melting and solidifying the resin member 41 in a state where the resin member 41 and the nonwoven fabric 42 are stacked on the edge portion 15c of the electrode plate 15 in this order. At this time, since the coefficient of thermal expansion of the nonwoven fabric 42 is smaller than the coefficient of thermal expansion of the resin member 41, the nonwoven fabric 42 can suppress the thermal expansion of the first portion 21 (resin member 41). As a result, the difference between the expansion amount of the first portion 21 and the expansion amount of the electrode plate 15 can be reduced, and the occurrence of wrinkles and warpage of the electrode plate 15 can be suppressed. Further, in the power storage device 1, since the non-woven fabric 42 constituting the separator 13 can suppress the thermal expansion of the first portion 21, for example, when a member different from the separator 13 is provided in order to suppress the thermal expansion of the first portion 21. Compared with, the parts cost can be reduced. Further, since the electrode laminate 11 is formed by laminating the electrode unit 20 in which the separator 13 and the bipolar electrode 14 are integrated, it is possible to suppress the positional deviation between the separator 13 and the bipolar electrode 14. ..

Further, in the power storage device 1, the separator 13 has a heat history in which heating up to the melting temperature of the first portion 21 is regarded once. As a result, the coefficient of thermal expansion of the nonwoven fabric 42 becomes the smallest at the time of the first heating, so that the thermal expansion of the first portion 21 can be effectively suppressed.

FIG. 4 is a graph showing an example of a change in the amount of elongation of the nonwoven fabric depending on the number of heatings. The figure shows the measurement result of the length of the nonwoven fabric when the temperature of the polyamide-based nonwoven fabric having a length of 23 mm is repeatedly and continuously changed between 25 ° C and 200 ° C at 25 ° C. .. Reference numeral S1 indicates the amount of elongation when the nonwoven fabric is heated for the first time, and reference numeral S2 indicates the subsequent change in the length of the nonwoven fabric.

As shown in FIG. 4, when the temperature is raised for the first time, the nonwoven fabric gradually shrinks in the range up to about 125 ° C. until the shrinkage amount reaches about 100 μm, and then the shrinkage amount exceeds 125 ° C. It contracts rapidly until it reaches about 530 μm. On the other hand, when the temperature of the nonwoven fabric is lowered from that state, the nonwoven fabric gradually expands until the shrinkage amount reaches about 340 μm in the range up to about 125 ° C., and then hardly deforms in the range below 125 ° C. At the time of the second and subsequent heating, the length of the non-woven fabric changes as in the case of the first temperature decrease.

As described above, in the non-woven fabric, the amount of shrinkage at the time of the first heating is the largest. That is, the coefficient of thermal expansion (linear expansion coefficient) at the time of initial heating is the smallest. The reason why the thermal expansion coefficient of the nonwoven fabric is the smallest at the first heating is that the nonwoven fabric before heating has thermal strain, and the thermal strain is released at the first heating. The coefficient of thermal expansion of the non-woven fabric at the time of the first heating changes depending on the material of the non-woven fabric, the manufacturing method, the shape of the fiber, and the like.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, as in the first modification shown in FIG. 5A, the outer edge of the separator 13 may be located outside the outer edge of the electrode plate 15 when viewed from the stacking direction of the electrode laminate 11. Even with such a first modification, it is possible to suppress wrinkles and warpage of the electrode plate 15, reduce component costs, and suppress misalignment of the separator 13, as in the above embodiment. Further, a bonding region between the separator 13 and the first portion 21 can be secured, and the separator 13 and the first portion 21 can be reliably coupled.

Further, as in the second modification shown in FIG. 5B, the outer edge of the separator 13 may be located inside the outer edge of the electrode plate 15 when viewed from the stacking direction of the electrode laminate 11. Similar to the above embodiment, the second modification can also suppress wrinkles and warpage of the electrode plate 15, reduce component costs, and suppress misalignment of the separator 13. Further, the electrode unit 20 can be miniaturized.

Further, in the above embodiment, the first portion 21 is formed only on the one surface 15a side of the electrode plate 15, but the first portion 21 is formed on both the one surface 15a side and the other surface 15b side. Alternatively, for example, the edge portion 15c of the electrode plate 15 may be formed so as to be buried in the first portion 21. Alternatively, the first portion 21 may be formed only on the other surface 15b side. Further, in the above embodiment, a part of the outside of the first portion 21 projects outward from the electrode plate 15, but if the first portion 21 is arranged at least between the edge portions 15c of the electrode plate 15. Often, for example, the entire first portion 21 may be arranged between the edge portions 15c of the electrode plate 15.

1 ... power storage device, 11 ... electrode laminate, 11a ... side surface, 12 ... sealant, 13 ... separator, 14 ... bipolar electrode, 15 ... electrode plate, 15a ... one side, 15b ... other side, 15c ... edge, 20 ... Electrode unit, 21 ... First part, 22 ... Second part, 41 ... Resin member, 42 ... Nonwoven fabric.

Claims (5)

A power storage device having a bipolar electrode composed of an electrode plate having a positive electrode formed on one side and a negative electrode formed on the other side.
A laminate in which the bipolar electrodes are laminated via a separator, and
A resin sealant provided so as to surround the edge of the bipolar electrode is provided.
The sealing body has at least a first portion arranged between the edges of the electrode plates and a second portion that surrounds the first portion from the outside along the side surface of the laminated body. ,
The first portion is welded to the edge portion of the electrode plate and the separator.
The separator is made of a non-woven fabric and is made of a non-woven fabric.
The coefficient of thermal expansion of the nonwoven fabric is smaller than the coefficient of thermal expansion of the first portion.
The laminated body is a power storage device configured by laminating an electrode unit in which the separator is coupled to the bipolar electrode via the first portion. The power storage device according to claim 1, wherein the outer edge of the separator is located outside the outer edge of the electrode plate when viewed from the stacking direction of the laminated body. The power storage device according to claim 1, wherein the outer edge of the separator is located inside the outer edge of the electrode plate when viewed from the stacking direction of the laminated body. A laminate in which a bipolar electrode consisting of an electrode plate having a positive electrode formed on one side and a negative electrode formed on the other side is laminated via a separator.
A resin-made encapsulation body provided so as to surround the edges of the bipolar electrode, at least along the first portion arranged between the edges of the electrode plates and the side surface of the laminate. A method for manufacturing a power storage device including the sealed body having the second portion surrounding the first portion from the outside.
The separator is formed by melting and solidifying the resin member in a state where the resin member and the non-woven fabric having a coefficient of thermal expansion smaller than the coefficient of thermal expansion of the resin member are stacked on the edge of the electrode plate in this order. A primary molding step of forming a plurality of electrode units coupled to the bipolar electrode via the first portion of the encapsulant.
A laminating step of forming the laminated body by laminating the electrode units, and
A method for manufacturing a power storage device, comprising a secondary molding step of forming the second portion of the sealed body, which surrounds the first portion from the outside along the side surface of the laminated body. In the primary molding step, the resin member and the non-woven fabric are placed on the resin member in a state where the non-woven fabric that has never been heated to the melting temperature of the resin member in the past is laminated on the resin member. The method for manufacturing a power storage device according to claim 4, wherein the heating is performed only once to a temperature equal to or higher than the welding temperature of the non-woven fabric and lower than the melting temperature of the non-woven fabric.

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