Electricity storage device

Abstract

The invention relates to a power storage device. The power storage device includes: a power storage module; and an outer body that accommodates the power storage module. The power storage module includes: a stacked electrode body; a major surface; and an outer peripheral surface. The main surface has: a plurality of first corners; and a plurality of edge portions. The outer peripheral surface has a plurality of end surfaces. Each end surface has a plurality of second corners. The outer body includes: a laminated sheet; and a plurality of protective sheets. The laminated sheet has: a main wall portion covering each of the first corner portions and each of the edge portions; and an outer peripheral wall portion. Each of the protective sheets is provided in a boundary region between the main wall portion and the outer peripheral wall portion in positions corresponding to the first corner portion and the plurality of second corner portions each connected to the first corner portion.

Description

Technical Field

[0001] The present disclosure relates to an electricity storage device. Background Art

[0002] Hitherto, various electricity storage devices have been known. Japanese Unexamined Patent Application Publication No. 2004-134210 (JP2004-134210 A) discloses a bipolar stacked battery as an example of an electricity storage device. In this stacked battery, sheet electrodes are stacked on an electrolyte layer. In the stacked battery, the electrodes are stacked in the outermost layer of the stack such that current collectors included in the electrodes are exposed to the outside of the battery in the stacking direction of the electrodes and serve as terminals.

[0003] Specifically, each of the current collectors of the two electrodes in the outermost layer is covered with a laminated sheet in which an opening is provided in the center. Four edges of each laminated sheet are sealed, and the edge of the opening of each laminated sheet is attached to the current collector by a sealing resin. As a result, the four edges of the electrolyte layer and the bipolar electrodes are depressurized and hermetically sealed. As each laminated sheet, a polymer metal composite film is used in which a heat-melting resin film, a metal foil, and a rigid resin film are stacked in the above order. Summary of the Invention

[0004] In JP 2004-134210 A, a plurality of electrodes are sandwiched between respective laminated sheets in the stacking direction, and thus a drawing process is applied to each laminated sheet in advance. By this drawing process, each laminated sheet is bent in the direction of the laminated sheet on the mating side at a position near the peripheral edge portion of the two electrodes in the outermost layer.

[0005] When a thermal shock is applied to such a stacked battery due to a rapid temperature change, there is a concern that the metal foil of the laminated sheet may be torn at the bent portion as described above. When the metal foil is torn, the sealing performance of the stacked battery obtained from the laminated sheet is lost.

[0006] Accordingly, the present disclosure provides an electricity storage device capable of maintaining the sealing performance of a stacked battery even when a thermal shock is applied.

[0007] According to one aspect of the present disclosure, an electricity storage device includes: an electricity storage module having a stacked electrode body in which a plurality of electrodes are stacked in a predetermined direction; and an outer body that houses the electricity storage module. The electricity storage module includes: a main surface whose normal direction is the predetermined direction; and an outer peripheral surface that extends from the main surface in the predetermined direction. The main surface has: a plurality of first corner portions; and a plurality of edge portions, each of the plurality of edge portions being sandwiched between two of the first corner portions. The outer peripheral surface has a plurality of end surfaces that are continuous in the circumferential direction of the electricity storage module. Each of the end surfaces has a plurality of second corner portions, each of the plurality of second corner portions being connected to a different one of the first corner portions. The outer body includes: a laminated sheet having a metal layer; and a plurality of protective sheets, each of the plurality of protective sheets being welded to the laminated sheet. The laminated sheet has: a main wall portion that covers each of the first corner portions and each of the edge portions; and an outer peripheral wall portion that covers each of the end surfaces. In a boundary region between the main wall portion and the outer peripheral wall portion, each of the protective sheets is provided at a position corresponding to the first corner portion and the plurality of second corner portions each of which is connected to the first corner portion.

[0008] According to such a configuration, in the boundary region between the main wall portion and the outer peripheral wall portion, the protective sheet is provided at a corner position corresponding to the first corner portion and the plurality of second corner portions each of which is connected to the first corner portion. Therefore, even when a crack occurs in the metal layer of the laminated sheet due to a thermal shock, the sealing performance at the corner position can be ensured. Therefore, even when a thermal shock is applied to the electricity storage device, the sealing performance of the electricity storage device can be maintained.

[0009] Each of the protective sheets may be a resin barrier film that is more resistant to thermal shock than the metal layer and may be covered by the laminated sheet.

[0010] According to such a configuration, it is possible to prevent the electrolytic solution injected into the electricity storage module from entering the laminate.

[0011] According to the present disclosure, even when a thermal shock is applied, the sealing performance of the stacked battery can be maintained. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Hereinafter, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the drawings, in which like reference numerals denote like elements, and in which:

[0013] Figure 1 is a perspective view of the stacked battery;

[0014] Figure 2 is alongFigure 1 A cross-sectional view taken along line II-II shown in

[0015] Figure 3 is Figure 1 a cross-sectional view taken along line III-III shown in

[0016] Figure 4 a perspective view of the structure;

[0017] Figure 5 a perspective view of the power storage module;

[0018] Figure 6 is Figure 1 a cross-sectional view taken along line VI-VI shown in

[0019] Figure 7 a cross-sectional view taken along line VI-VI after applying a thermal shock; Figure 1 shown in

[0020] Figure 8A a diagram for describing the manufacturing method of the first lamination part;

[0021] Figure 8B a diagram for describing the manufacturing method of the first lamination part;

[0022] Figure 8C a diagram for describing the manufacturing method of the first lamination part;

[0023] Figure 8D a diagram for describing the manufacturing method of the first lamination part;

[0024] Figure 8E a diagram for describing the manufacturing method of the first lamination part;

[0025] Figure 8F a diagram for describing the manufacturing method of the first lamination part;

[0026] Figure 8G a diagram for describing the manufacturing method of the first lamination part;

[0027] Figure 8H a diagram for describing the manufacturing method of the first lamination part;

[0028] Figure 9A a diagram for describing the method of manufacturing a stacked battery from a power storage module and an external body;

[0029] Figure 9B a diagram for describing the method of manufacturing a stacked battery from a power storage module and an external body;

[0030] Figure 9Cis a diagram for describing a method of manufacturing a stacked battery using a power storage module and an external body; and

[0031] Figure 9D is a diagram for describing a method of manufacturing a stacked battery using a power storage module and an external body. DETAILED DESCRIPTION

[0032] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the embodiments described below, the same or common parts are denoted by the same reference numerals in the drawings, and their descriptions will not be repeated.

[0033] As an example of a power storage device, a stacked battery will be described below as an example. The stacked battery is mounted on an electric vehicle (for example, a hybrid electric vehicle that travels using the power of at least one of a motor and an engine, and an electric vehicle that travels by a driving force obtained from electric energy).

[0034] The stacking direction of the electrodes in the stacked battery is also referred to as the "DR3 direction" hereinafter. The direction perpendicular to the stacking direction and being the short direction of the stacked battery is also referred to as the "DR1 direction". The direction perpendicular to the stacking direction and being the longitudinal direction of the stacked battery is also referred to as the "DR2 direction". The DR1 direction, DR2 direction, and DR3 direction are orthogonal to each other.

[0035] Figure 1 is a perspective view of a stacked battery according to an embodiment of the present invention. Figure 2 is along Figure 1 a cross-sectional view taken along line II-II shown in. Figure 3 is along Figure 1 a cross-sectional view taken along line III-III shown in. Referring to Figures 1 to 3 , a stacked battery 100 according to the present embodiment will be described.

[0036] As shown in Figures 1 to 3 , the stacked battery 100 includes a power storage module 1, a structure body 60( Figure 3 ), and an external body 20. The power storage module 1 has a resin sealing body 40 and a stacked electrode body 10 in which a plurality of electrodes (electrode plates 11) to be described later are stacked in the stacking direction. The external body 20 houses the power storage module 1 and the structure body 60.

[0037] The power storage module 1 also has: a first main surface 91; a second main surface 92 on the side opposite to the first main surface 91; and an outer peripheral surface 93. The first main surface 91 and the second main surface 92 are end surfaces in the DR3 direction. The first main surface 91 and the second main surface 92 are parallel to each other. The first main surface 91 and the second main surface 92 are surfaces extending in the DR1 direction and the DR2 direction. The first main surface 91 is the surface that contacts the first conductive plate 18 described later. The second main surface 92 is the surface that contacts the second conductive plate 19 described later.

[0038] The outer peripheral surface 93 is a surface perpendicular to the first main surface 91 and the second main surface 92. In this example, the outer peripheral surface 93 is constructed by four end surfaces 93a to 93d (see Figure 2 , Figure 3 and Figure 7 ). Each of the end surfaces 93a to 93d is a side surface of the resin sealing body 40. In this example, each of the end surfaces 93a to 93d is a flat surface having a rectangular shape.

[0039] The external body 20 is electrically connected to the terminal electrodes of the stacked electrode body 10 described later, and is arranged so that current can be led to the outside from the stacking direction. The external body 20 includes a first conductive plate 18, a second conductive plate 19, a first laminated sheet portion 21, a second laminated sheet portion 22, a resin sheet 50, and eight protective sheets 80. The stacked battery 100 is, for example, a secondary battery such as a lithium-ion battery.

[0040] In Figure 1 , among the eight protective sheets 80, four protective sheets 80 on the first laminated sheet portion 21 side are shown. The remaining four protective sheets 80 are positioned on the second laminated sheet portion 22 side. The four protective sheets 80 on the first laminated sheet portion 21 side and the four protective sheets 80 on the second laminated sheet portion 22 side are positioned to face each other in the DR3 direction. The four protective sheets 80 on the first laminated sheet portion 21 side and the four protective sheets 80 on the second laminated sheet portion 22 side are located at the eight corners (specifically, the inner sides of the corners) of the stacked battery 100.

[0041] The four protective sheets 80 on the first laminated sheet portion 21 side are covered by the second sheet 32 of the first laminated sheet portion 21 described later (the state in Figure 8G ). The four protective sheets 80 of the second laminated sheet portion 22 are also covered from the outside by the second sheet 32 of the second laminated sheet portion 22.

[0042] The second sheet 32 of the first lamination part 21 has a main wall part 251 and an outer peripheral wall part 252. Similarly, the second sheet 32 of the second lamination part 22 also has a main wall part 251 and an outer peripheral wall part 252. The main wall part 251 is parallel to the first main surface 91 of the power storage module 1. The outer peripheral wall part 252 is parallel to the outer peripheral surface 93 of the power storage module 1.

[0043] The stacked electrode body 10 includes the plurality of electrode plates 11, a plurality of separators 15, a positive electrode terminal electrode 16, and a negative electrode terminal electrode 17. The plurality of electrode plates 11, the positive electrode terminal electrode 16, and the negative electrode terminal electrode 17 are stacked in the stacking direction ( Figure 2 and Figure 3 the DR3 direction in) by the separators 15.

[0044] The separator 15 is formed in a sheet shape. Examples of the separator 15 include: a porous film formed of a polyolefin resin such as polyethylene (PE) and polypropylene (PP); and a woven fabric or a non-woven fabric formed of polypropylene, methyl cellulose, etc. The separator 15 can be reinforced with a vinylidene fluoride resin compound.

[0045] The plurality of electrode plates 11 are disposed between the positive electrode terminal electrode 16 and the negative electrode terminal electrode 17. The electrode plate 11 is, for example, a bipolar electrode. The electrode plate 11 includes a current collector 12, a positive electrode layer 13, and a negative electrode layer 14.

[0046] The current collector 12 may contain at least one type selected from the group formed by, for example, aluminum (Al), stainless steel, nickel (Ni), chromium (Cr), platinum (Pt), niobium (Nb), iron (Fe), titanium (Ti), and zinc (Zn). The current collector 12 can be obtained by applying an electroplating process on the front surface of a metal foil.

[0047] The current collector 12 has a first surface 12a on one side in the stacking direction and a second surface 12b on the other side in the stacking direction. The negative electrode layer 14 is provided on the first surface 12a. The positive electrode layer 13 is provided on the second surface 12b.

[0048] The positive electrode terminal electrode 16 is located on one side in the stacking direction. The positive electrode terminal electrode 16 includes a current collector 12 and a positive electrode layer 13. Specifically, in the positive electrode terminal electrode 16, the negative electrode layer 14 and the positive electrode layer 13 are not provided on the first surface 12a of the current collector 12, and the positive electrode layer 13 is provided on the second surface 12b of the current collector 12. The first conductive plate 18 is provided on the first surface 12a of the current collector 12 in the positive electrode terminal electrode 16. The central portion (the portion other than the peripheral edge portion) of the first surface 12a of the current collector 12 in the positive electrode terminal electrode 16 constitutes a part of the first main surface 91. The first main surface 91 includes the central portion of the first surface 12a of the current collector 12 in the positive electrode terminal electrode 16 and the upper surface of the resin sealing body 40.

[0049] The negative electrode terminal electrode 17 is located on the other side in the stacking direction. The negative electrode terminal electrode 17 includes a current collector 12 and a negative electrode layer 14. Specifically, in the negative electrode terminal electrode 17, the negative electrode layer 14 is provided on the first surface 12a of the current collector 12, and the negative electrode layer 14 and the positive electrode layer 13 are not provided on the second surface 12b of the current collector 12. The second conductive plate 19 is provided on the second surface 12b of the current collector 12 in the negative electrode terminal electrode 17. The central portion (the portion other than the peripheral edge portion) of the second surface 12b of the current collector 12 in the negative electrode terminal electrode 17 constitutes a part of the second main surface 92. The second main surface 92 includes the central portion of the second surface 12b of the current collector 12 in the negative electrode terminal electrode 17 and the lower surface of the resin sealing body 40.

[0050] The positive electrode layer 13 is formed as a result of applying a positive electrode active material to the second surface 12b. For example, as the positive electrode active material, a positive electrode active material capable of blocking and releasing charge carriers (such as lithium ions) can be used. Specifically, as the positive electrode active material, a lithium ion composite metal oxide having a layered rock salt structure, a metal oxide having a spinel structure, a polyanion compound, etc., which can be used as the positive electrode active material of a lithium ion secondary battery, can be adopted. For example, two or more types of positive electrode active materials can be used together, and the positive electrode active material can contain olivine type lithium iron phosphate (LiFePO4).

[0051] The negative electrode layer 14 is formed as a result of applying a negative electrode active material to the first surface 12a. As the negative electrode active material, for example: lithium; carbon; metal compounds; and elements capable of alloying with lithium; their compounds, etc., can be adopted.

[0052] In all of the plurality of electrode plates 11, the negative electrode terminal electrode 17, and the positive electrode terminal electrode 16, the peripheral edge portion of the current collector 12 is an uncoated area where the positive electrode layer 13 and the negative electrode layer 14 are not provided.

[0053] The resin sealing body 40 is provided to seal the periphery of the stacked electrode body 10. Specifically, the resin sealing body 40 seals the battery space formed between two adjacent electrode plates 11. An electrolytic solution is injected into this battery space. In other words, the electrolytic solution is injected into the power storage module 1. The resin sealing body 40 is formed by curing a resin member (such as a hot melt member, a thermoplastic resin, a thermosetting resin, or a photocurable resin). The resin sealing body 40 is provided on the above-mentioned uncoated area.

[0054] The first conductive plate 18 and the second conductive plate 19 are provided to sandwich the stacked electrode body 10 in the stacking direction. Specifically, the first conductive plate 18 is provided on the first surface 12a of the current collector 12 included in the positive electrode terminal electrode 16. In other words, the first conductive plate 18 is provided on the first main surface 91 of the current collector 12 included in the positive electrode terminal electrode 16. The first conductive plate 18 is electrically connected to the positive electrode terminal electrode 16 by abutting against the first surface 12a. The first conductive plate 18 serves as the positive electrode terminal of the stacked battery 100 by being electrically connected to the positive electrode terminal electrode 16.

[0055] The second conductive plate 19 is provided on the second surface 12b of the current collector 12 included in the negative electrode terminal electrode 17. In other words, the second conductive plate 19 is provided on the second main surface 92 of the current collector 12 included in the negative electrode terminal electrode 17. The second conductive plate 19 is electrically connected to the negative electrode terminal electrode 17 by abutting against the second surface 12b. The second conductive plate 19 serves as the negative electrode terminal of the stacked battery 100 by being electrically connected to the negative electrode terminal electrode 17.

[0056] In the stacked battery 100, current can be led from the power storage module 1 accommodated inside to the outside via the first conductive plate 18 serving as the positive electrode terminal and the second conductive plate 19 serving as the negative electrode terminal, without using a tab for leading the current to the outside.

[0057] The first conductive plate 18 and the second conductive plate 19 have a rectangular shape with a plurality of corners. The peripheral edges of the first conductive plate 18 and the second conductive plate 19 are located on the resin sealing body 40.

[0058] In this example, the first conductive plate 18 and the second conductive plate 19 are aluminum (Al) plates. The first conductive plate 18 and the second conductive plate 19 are not limited thereto, and may include at least one type selected from the group consisting of aluminum (Al), stainless steel, nickel (Ni), chromium (Cr), platinum (Pt), niobium (Nb), iron (Fe), titanium (Ti), and zinc (Zn). The current collector 12 can be obtained by applying an electroplating process on the front surface of a metal foil.

[0059] The first lamination part 21 is joined to the peripheral edge of the first conductive plate 18. The first lamination part 21 is joined to the first conductive plate 18 in a state where the resin sheet 50 is interposed between the first lamination part 21 and the peripheral edge of the first conductive plate 18. The second lamination part 22 is joined to the peripheral edge of the second conductive plate 19. The second lamination part 22 is joined to the second conductive plate 19 in a state where the resin sheet 50 is interposed between the second lamination part 22 and the peripheral edge of the second conductive plate 19.

[0060] In this example, the resin sheet 50 is formed of a resin material having insulation properties. The resin sheet 50 is formed of a resin material that can be welded to the first conductive plate 18 and the second conductive plate 19. In this example, the resin sheet 50 is an insulating sealant film.

[0061] Specifically, the resin sheet 50 has resin layers 51, 52, 53. The resin layer 51 is the layer on the inner side. The resin layer 53 is the layer on the outer side. The resin layer 52 is sandwiched between the resin layer 51 and the resin layer 53.

[0062] The resin layers 51, 53 are sealant resin layers. As will also be described later Figure 8B and Figure 8C shown in the state of, in this example, the resin layers 51, 53 are acid-modified (PPa) layers. The resin layer 51 is thermally welded to the first conductive plate 18. In this example, the resin layer 52 is a polypropylene (PP) layer.

[0063] The type of resin constituting each of the resin layers 51 to 53 is not limited to the above, and for example, thermoplastic resins (such as polyethylene, polypropylene, modified polyethylene, and modified polypropylene) can be appropriately used.

[0064] The central portions of the first conductive plate 18 and the second conductive plate 19 are exposed areas not covered by the resin sheet 50, the first lamination part 21, and the second lamination part 22. Current can be directly led to the outside from the power storage module 1 accommodated therein via these exposed areas.

[0065] The first lamination part 21 includes the plurality of first sheets 31 and the plurality of second sheets 32 (see Figure 2 , Figure 3 and Figure 6)。The plurality of first sheets 31 and the plurality of second sheets 32 cooperatively cover the peripheral edge of the first conductive plate 18. The second lamination part 22 includes the plurality of first sheets 31 and the plurality of second sheets 32. The plurality of first sheets 31 and the plurality of second sheets 32 included in the second lamination part 22 cooperatively cover the peripheral edge of the second conductive plate 19.

[0066] The first sheet 31 (see Figure 2 ) has a first metal layer 310 and sealant resin layers 311, 312. The first metal layer 310 has a sheet shape. In this example, as also shown in the state described later Figure 8E , the first metal layer 310 is an aluminum foil (Al foil) layer. The first metal layer 310 is not limited to Al foil, and metal foils such as Ni foil, Cu foil, and stainless steel foil can also be used. The first metal layer 310 imparts moisture permeability resistance, air permeability resistance, and chemical resistance to the first sheet 31.

[0067] The sealant resin layers 311, 312 are provided on two surfaces of the first metal layer 310. Specifically, the sealant resin layer 311 is provided on the inner front surface of the first metal layer 310. The sealant resin layer 312 is provided on the outer front surface of the first metal layer 310.

[0068] The sealant resin layers 311, 312 are compatible with the resin sheet 50. In this example, polypropylene (PP) is used as the sealant resin layers 311, 312, but the present invention is not limited thereto, and a thermoplastic resin (such as polyethylene, polypropylene, modified polyethylene, and modified polypropylene) can be used as the sealant resin layers 311, 312.

[0069] The sealant resin layers 311, 312 serve as a sealing layer of the external body 20. The sealant resin layers 311, 312 also have the function of an insulating layer, and when the first lamination part 21 and the second lamination part 22 are joined to each other, the resin layers 311, 312 insulate the first lamination part 21 and the second lamination part 22 from each other.

[0070] The second sheet 32 (see Figure 3 ) has a second metal layer 320, a first resin layer 321, a second resin layer 322, a third resin layer 323, and a fourth resin layer 324. In the second sheet 32, the third resin layer 323, the first resin layer 321, the second metal layer 320, the second resin layer 322, and the fourth resin layer 324 are stacked in this order from the inside to the outside of the stacked battery 100. The fourth resin layer 324 is the outermost layer in the second sheet 32.

[0071] In this example, as also shown in the state described later Figure 8FAs shown in the state of , the second metal layer 320 is an Al foil layer. The first resin layer 321 is an acid-modified (PPa) layer. The second resin layer 322 is a nylon layer. The third resin layer 323 is a polypropylene (PP) layer. The fourth resin layer 324 as the outermost layer is a polyethylene terephthalate (PET) layer. The first resin layer 321 is disposed on the first major surface 320a. The second resin layer 322 is disposed on the second major surface 320b.

[0072] The second metal layer 320 has a sheet shape. The second metal layer 320 has a first major surface 320a and a second major surface 320b. The first major surface 320a is the surface facing inward (the side where the stacked electrode body 10 is located), and the second major surface 320b is the surface facing outward (the side opposite to the side where the stacked electrode body 10 is located).

[0073] The second metal layer 320 is not limited to Al foil, and metal foils such as Ni foil, Cu foil, and stainless steel foil can be used. The thickness of the second metal layer 320 can be thicker than the thickness of the first metal layer 310. The thickness of the second metal layer 320 can be the same as the thickness of the first metal layer 310.

[0074] The third resin layer 323 is compatible with the sealant resin layer 312. As the third resin layer 323, in addition to polypropylene (PP), a hot-melt resin such as polyethylene, modified polyethylene, and modified polypropylene can also be used. A resin material having immiscibility with the sealant resin layer 312 can be used in the fourth resin layer 324.

[0075] In the second sheet 32, the nylon layer (second resin layer 322) and the polyethylene terephthalate layer (fourth resin layer 324) are overlapped on the outside of the second metal layer 320. Therefore, compared with the combination of the two layers (first resin layer 321 and third resin layer 323) on the inside of the second metal layer 320 in the second sheet 32, the combination of the layers on the outside of the second metal layer 320 has higher strength. The expression "higher strength" means high rigidity or tensile strength. As a result, it is possible to appropriately prevent damage to the second metal layer 320 when the second sheet 32 receives an external force such as piercing.

[0076] The sealant resin layer 312 of the first sheet 31 (see Figure 2 ) is the polypropylene (PP) layer as described above. Therefore, the combination of the layers on the outside of the second metal layer 320 of the second sheet 32 has higher strength than the sealant resin layer 312 of the first sheet 31. Therefore, the combination of the layers on the outside of the second metal layer 320 in the second sheet 32 has higher strength than the sealant resin layer 312 of the first sheet 31. By enhancing the strength of the second sheet 32, it is possible to appropriately prevent damage to the second sheet 32 during the deep drawing forming described later.

[0077] The first lamination part 21 is deep drawn and formed in a state of being joined to the first conductive plate 18. In other words, a drawing process is applied to the first lamination part 21. As a result, the first lamination part 21 has a shape that is open upward and downward. A flange part 21f that is bent outward is provided at the open end on the lower side of the first lamination part 21.

[0078] The second lamination part 22 is deep drawn and formed in a state of being joined to the second conductive plate 19. In other words, like the first lamination part 21, a drawing process is also applied to the second lamination part 22. As a result, the second lamination part 22 has a shape that is open upward and downward. A flange part 22f that is bent outward is provided at the open end on the upper side of the second lamination part 22.

[0079] Accommodating recesses 21c, 22c for accommodating the inner power storage module 1 are provided on the first lamination part 21 and the second lamination part 22. A part of the first main surface 91, a part of the second main surface 92, and the outer peripheral surface 93 in the power storage module 1 are covered by the accommodating recesses 21c, 22c.

[0080] Specifically, the peripheral edge parts of the upper surface and the lower surface of the power storage module 1 and the outer peripheral surface of the power storage module 1 are covered by the accommodating recesses 21c, 22c. Specifically, the peripheral edge parts of the upper surface and the lower surface of the stacked electrode body 10 and the outer peripheral surface of the stacked electrode body 10 are covered by the accommodating recesses 21c, 22c. The central part of the upper surface of the stacked electrode body 10 is covered by the first conductive plate 18. The central part of the lower surface of the stacked electrode body 10 is covered by the second conductive plate 19.

[0081] For example, the accommodating recesses 21c, 22c are formed by parts formed by applying the above-described drawing process to the first lamination part 21 and the second lamination part 22. The accommodating recesses 21c, 22c are not limited to this part, and only need to be provided so as to be able to accommodate the stacked electrode body 10. In the above description, the case where the accommodating recesses are provided in both the first lamination part 21 and the second lamination part 22 has been exemplified, but the accommodating recesses may be provided in only one of the first lamination part 21 and the second lamination part 22.

[0082] The first sheet 31 has an inner end part 31i located on the central side of the stacked electrode body 10. The second sheet 32 has an inner end part 32i located on the central side of the stacked electrode body 10. The resin sheet 50 has an inner edge part 50i and an outer edge part 50c located on the central side of the stacked electrode body 10.

[0083] The inner edge portion 50i is positioned closer to the central side of the stacked electrode body 10 than the inner end portions 31i and 32i, so as to ensure the insulation distance between the first metal layer 310 of the first sheet 31 and the second metal layer 320 of the second sheet 32 and the first conductive plate 18 and the second conductive plate 19.

[0084] The first conductive plate 18 has an outer edge portion 18c. The second conductive plate 19 has an outer edge portion 19c. The inner end portions 31i and 32i are positioned closer to the central side of the stacked electrode body 10 than the outer edge portions 18c and 19c.

[0085] The portions of the first conductive plate 18 and the second conductive plate 19 that overlap with the resin sheet 50 are welded. The bonding interface of the overlapping portions is sealed.

[0086] The outer edge portion 50c of the resin sheet 50 is located outside the outer edge portions 18c and 19c, but is not limited thereto, and the outer edge portion 50c and the outer edge portions 18c and 19c may be flush with each other.

[0087] By bonding the first sheet 31 and the second sheet 32 to the first conductive plate 18 and the second conductive plate 19 via the resin sheet 50, the situation where the first conductive plate 18 and the second conductive plate 19 are short-circuited via the first sheet 31 having the first metal layer 310 or the second sheet 32 having the second metal layer 320 is reduced.

[0088] Next, the structure 60 is described. As described above, the structure 60 is housed in the outer body 20. As Figure 3 shown, the structure 60 is disposed in a state facing the outer peripheral surface 93 (specifically, the end surfaces 93a and 93c) of the power storage module 1.

[0089] Figure 4 is a perspective view of the structure 60. As Figure 4 shown, in this example, the structure 60 has a box shape. The structure 60 is generally formed of resin. The structure 60 includes a base portion 61 that extends in the DR3 direction in a side view of the power storage module 1 (see Figure 3 ).

[0090] The structure 60 further includes two wall portions 62 and 64 that extend from the base portion 61 parallel to the first main surface 91 of the power storage module 1 and extend in the DR2 direction toward the outer peripheral surface 93. The structure 60 further includes two wall portions 63 and 65 that extend from the base portion 61 perpendicular to the first main surface 91 and extend in the DR2 direction toward the outer peripheral surface 93.

[0091] The wall portions 62, 63, 64, 65 rising from the base portion 61 are continuous with each other in the above order. The wall portion 62 is positioned on the side of the first conductive plate 18. The wall portion 64 is positioned on the side of the second conductive plate 19. A rectangular parallelepiped space 690 having an opening is formed by the base portion 61 and each of the wall portions 62, 63, 64, 65.

[0092] The structure 60 has an outer front surface 60s and an inner front surface 60t on the outer peripheral surface 93 side of the outer front surface 60s. The first laminated sheet portion 21 and the second laminated sheet portion 22 (see Figure 1 ) of the structural outer body 20 are provided to cover the outer front surface 60s of the structure 60. Specifically, each of the second sheets 32 of the first laminated sheet portion 21 and the second laminated sheet portion 22 (see Figure 3 ) is provided to cover the outer front surface 60s of the structure 60.

[0093] Between the inner front surface 60t of a part of the base portion 61 in the structure 60 and the end surface 93a of the power storage module 1, a sealed internal space 800 is formed by each of the second sheets 32 of the first laminated sheet portion 21 and the second laminated sheet portion 22 as shown in Figure 3 . The internal space 800 is decompressed so as to have a negative pressure with respect to the air pressure (atmospheric pressure in this example) in the external space of the stacked battery 100. In this example, the internal space 800 is decompressed to about 1 kilopascal (kPa) in the initial state. The internal space 800 is placed in a low vacuum state by evacuation. By the pressure difference between the internal space 800 and the external space of the stacked battery 100 generated by this decompression, a binding force is applied to the stacked electrode body 10.

[0094] As described above, the stacked battery 100 as an example of a power storage device includes a power storage module 1 having a stacked electrode body 10 and having a first main surface 91, a second main surface 92, and an outer peripheral surface 93 perpendicular to the first main surface 91 and the second main surface 92. As shown in Figure 2 and Figure 3 , the stacked battery 100 further includes an outer body 20 that houses the power storage module 1. As shown in Figure 3 and Figure 4 , the outer body 20 includes a structure 60 that has an outer front surface 60s and an inner front surface 60t on the outer peripheral surface 93 side of the outer front surface 60s and is disposed in a state facing the outer peripheral surface 93.

[0095] As shown in Figure 3 , the outer body 20 further includes a first laminated sheet portion 21 and a second laminated sheet portion 22 provided to cover the outer front surface 60s. As shown in Figure 3As shown in the figure, a sealed internal space 800 is formed between the inner front surface 60t and the outer peripheral surface 93 by the first pressing portion 21 and the second pressing portion 22. The internal space 800 is decompressed so as to have a negative pressure with respect to the air pressure in the external space of the stacked battery 100.

[0096] Figure 5 is a perspective view of the power storage module 1. As Figure 5 shown in the figure, the power storage module 1 includes a first main surface 91 and an outer peripheral surface 93. As described above, the power storage module 1 further includes a second main surface 92 on the side opposite to the first main surface 91 ( Figure 2 and Figure 3 ). The outer peripheral surface 93 is composed of four rectangular end surfaces 93a to 93d. The directions of the normal lines of the first main surface 91 and the second main surface 92 are in the DR3 direction. The outer peripheral surface 93 extends from the first main surface 91 or the second main surface 92 in the DR3 direction.

[0097] The first main surface 91 has a plurality of corner portions 911 and a plurality of edge portions 912, and each edge portion 912 is sandwiched between two corner portions 911. In this example, the first main surface 91 has four corner portions 911 and four edge portions 912.

[0098] As described above, the outer peripheral surface 93 has the plurality of end surfaces 93a to 93d that are continuous in the circumferential direction of the power storage module 1. Each of the end surfaces 93a to 93d has a plurality of corner portions 921, and each corner portion 921 is connected to each corner portion 911 differently. In this example, each of the end surfaces 93a to 93d has four corner portions 921. Each of the two corner portions 921 on the first main surface 91 side among the four corner portions 921 is connected to a different one of the corner portions 911 of the first main surface 91. One corner (specifically, a three-dimensional corner) of the power storage module 1 is composed of one corner portion 911 and two corner portions 921 (specifically, two consecutive corner portions 921 of different end surfaces) connected to the corner portion 911.

[0099] Similar to the first main surface, the second main surface 92 also has four corner portions 911 and four edge portions 912. Each of the two corner portions 921 on the second main surface 92 side among the four corner portions 921 is connected to a different one of the corner portions 911 of the second main surface 92.

[0100] Figure 6 is a cross-sectional view taken along the Figure 1 line VI-VI shown in the figure. As Figure 6As shown, the first lamination part 21 has the second sheet 32 and the protective sheet 80. As described above, in the second sheet 32, the third resin layer 323, the first resin layer 321, the second metal layer 320, the second resin layer 322, and the fourth resin layer 324 are stacked in this order from the inside to the outside of the stacked battery 100.

[0101] The protective sheet 80 is disposed between the corner part 911 and the plurality of corner parts 921 connected to the corner part 911 and the second sheet 32. The protective sheet 80 is a resin barrier film. The resin barrier film includes a resin having high gas barrier properties.

[0102] Resins containing vinyl alcohol such as EVOH and polyvinyl alcohol (PVA) as monomers exhibit high gas barrier properties because the molecules can aggregate in a compact manner. A resin barrier film obtained by multilayering such gas barrier resins on a resin with low moisture permeability (such as PP and PE used in sealant resins) inhibits (blocks) the permeation of air and electrolytic solution (gas) leaking through the resin seal part of the module. The resin barrier film as described above is used as the protective sheet 80.

[0103] The protective sheet 80 is more resistant to thermal shock than the second metal layer 320. The protective sheet 80 has, in order from the inside to the outside of the stacked battery 100, a second resin layer 821, a first resin layer 820, and a third resin layer 822. The first resin layer 820 is an ethylene-vinyl alcohol copolymer (EVOH) layer. The second resin layer 821 and the third resin layer 822 are polypropylene (PP) layers.

[0104] The protective sheet 80 is welded to the second sheet 32. Specifically, the protective sheet 80 is welded to the third resin layer 323 of the second sheet 32. More specifically, the third resin layer 822 of the protective sheet 80 and the third resin layer 323 of the second sheet 32 are welded to each other.

[0105] The main wall part 251 of the first lamination part 21 (see Figures 1 to 3 ) covers each corner part 911 and each edge part 912 of the first main surface 91. The outer peripheral wall part 252 of the first lamination part 21 covers each end surface 93a to 93d. Similarly, the main wall part 251 of the second lamination part 22 covers each corner part 911 and each edge part 912 of the second main surface 92. The outer peripheral wall part 252 of the second lamination part 22 covers each end surface 93a to 93d.

[0106] In the boundary region R between the main wall part 251 and the outer peripheral wall part 252 (see Figure 2 and Figure 3) In positions corresponding to the corner portion 911 and two corner portions 921 each connected to the corner portion 911, respective protective sheets 80 are provided. Specifically, as an example, the corner portion 911 of the first main surface 91, the corner portion 921 of the end surface 93b of the outer peripheral surface 93, and the corner portion 921 of the end surface 93c of the outer peripheral surface 93 face a second resin layer 821 of the protective sheet 80 ( Figure 6 a part of the second resin layer 821 shown in

[0107] When focusing on the first main surface 91 among the first main surface 91 and the second main surface 92 as described above, the stacked battery 100 has the following structure.

[0108] As Figure 2 and Figure 3 shown in

[0109] As Figure 5 shown in

[0110] As Figure 1 and Figure 6 shown in Figure 5 the stacked battery 100 includes: a power storage module 1 having a stacked electrode body 10 in which a plurality of electrodes are stacked in the DR3 direction (stacking direction); and an outer body 20 that houses the power storage module 1. The power storage module 1 includes: a first main surface 91 whose normal direction is the DR3 direction; and an outer peripheral surface 93 that extends from the first main surface 91 in the DR3 direction.

[0109] As Figure 5 shown in

[0110] As Figure 1 and Figure 6 shown in Figure 5 the stacked battery 100 includes: a power storage module 1 having a stacked electrode body 10 in which a plurality of electrodes are stacked in the DR3 direction (stacking direction); and an outer body 20 that houses the power storage module 1. The power storage module 1 includes: a first main surface 91 whose normal direction is the DR3 direction; and an outer peripheral surface 93 that extends from the first main surface 91 in the DR3 direction. Figure 2 and Figure 3 ) In positions corresponding to the corner portion 911 and the plurality of corner portions 921 each connected to the corner portion 911, respective protective sheets 80 are provided.

[0111] Figure 7 is a cross-sectional view taken along the line VI-VI shown in Figure 1 after applying a thermal shock. AsFigure 7 As shown, due to thermal shock, a crack 399 occurs in the second metal layer 320 of the second sheet 32. When the crack 399 occurs, the sealing property of the second sheet 32 is lost.

[0112] In the boundary region R between the main wall portion 251 and the outer peripheral wall portion 252 ( Figure 2 and Figure 3 ), at positions corresponding to the corner portion 911 and the plurality of corner portions 921 each connected to the corner portion 911 (hereinafter also referred to as "corner positions"), cracks are more likely to occur in the second metal layer 320 due to thermal shock compared to other positions. Therefore, by disposing the protective sheet 80 at the corner positions as shown in Figure 6 and Figure 7 , even when the crack 399 occurs, the sealing property of the first laminated sheet portion 21 can be ensured. The same can be said for the second laminated sheet portion 22. As described above, according to the stacked battery 100, the sealing property of the stacked battery 100 can be maintained even when thermal shock is applied.

[0113] Each protective sheet 80 is a resin barrier film that is more resistant to thermal shock than the second metal layer 320 and is covered by the second sheet 32. Therefore, it is possible to prevent the electrolytic solution injected into the power storage module 1 from entering the second sheet 32.

[0114] Figure 8A , Figure 8B , Figure 8C , Figure 8D , Figure 8E , Figure 8F , Figure 8G and Figure 8H are diagrams for describing the manufacturing method of the first laminated sheet portion 21. As shown in the state of Figure 8A , an aluminum plate used as the first conductive plate 18 is prepared. As shown in the state of Figure 8B , two resin sheets 50 are welded along the two long edges of the aluminum plate. Next, as shown in the state of Figure 8C , two resin sheets 50 are welded along the two short edges of the aluminum plate. The resin sheets 50 on the long edge side and the resin sheets 50 on the short edge side overlap at the four corner portions shown in the state of Figure 8C .

[0115] As shown in Figure 8DAs shown in the state of , two resin sheets 70 are welded to each of the two resin sheets 50 on the long edge side. In this example, each resin sheet 70 has the same structure as the resin sheet 50. The two resin sheets 70 on the right side of the figure are spaced apart from each other in the DR2 direction and extend in the D1 direction. Similarly, the two resin sheets 70 on the left side of the figure are also spaced apart from each other in the DR2 direction and extend in the D1 direction. The four resin sheets 70 are welded to the resin sheet 50 on the long edge side in a state extending from the resin sheet 50 in the direction of the side opposite to the aluminum plate.

[0116] like Figure 8E As shown in the state, the protective sheet 80 is welded to Figure 8D Each of the four corners of the middle body of the first laminated sheet portion 21 shown in the state. In detail, the protective sheet 80 is welded to the two longitudinal direction ends of the two resin sheets 50 on the short edge side. In other words, in the drawings, the protective sheet 80 is welded to the upper resin sheet 50 and the lower resin sheet 50. Four protective sheets 80 are welded to the resin sheets 50.

[0117] like Figure 8F As shown in the state of FIG. 1 , one first sheet 31 is welded to the resin sheet 50 and two resin sheets 70 on the right side of the figure. Similarly, one first sheet 31 is also welded to the resin sheet 50 and two resin sheets 70 on the left side of the figure. Each first sheet extends in the DR2 direction. Each first sheet is longer than the spacing distance between the resin sheets 70 in the DR2 direction.

[0118] like Figure 8G As shown in the state, a second sheet 32 ​​is welded to the resin sheet 50 on the upper side in the figure, the two resin sheets 70 on the upper side in the figure, the ends of the two first sheets 31 (the ends on the upper side in the figure), and the two protective sheets 80 on the upper side in the figure. The second sheet 32 ​​has a U-shape. Similarly, a second sheet 32 ​​is also welded to the resin sheet 50 on the lower side in the figure, the two resin sheets 70 on the lower side in the figure, the ends of the two first sheets 31 (the ends on the lower side in the figure), and the two protective sheets 80 on the lower side of the figure. The second sheets 32 are placed in a state facing the DR2 direction by being spaced apart from each other. Shown as Figure 8G The intermediate body of the first laminate sheet portion 21 in the state of being line-symmetrical in each of the DR1 direction and the DR2 direction.

[0119] By applying a drawing process along an imaginary line L on the intermediate body, such as Figure 8H The first laminated sheet portion 21 is produced as shown in the state. Through this drawing process, the flange portion 21f of the first laminated sheet portion 21 is formed. Figure 8G In the top view of the intermediate body of the first laminated sheet portion 21 shown in the state, the imaginary line L overlaps with each protective sheet 80. Figure 8H andFigure 1 As shown in the state of Figure 1 , each protective sheet 80 is positioned inside (at the corner) of the corner of the first lamination part 21.

[0120] The first lamination part 21 and the second lamination part 22 have the same shape. The second lamination part 22 is also manufactured by a method similar to that of the first lamination part 21. Therefore, the description of the manufacturing method of the second lamination part 22 will not be repeated here.

[0121] Figure 9A 、 Figure 9B 、 Figure 9C and Figure 9D are diagrams for describing the method of manufacturing the stacked battery 100 from the power storage module 1, the structure body 60, and the external body 20. As Figure 9A and Figure 9B shown in the state of Figure 9A and Figure 9B , the structure body 60 is mounted on one of the two short-edge sides of the power storage module 1. The structure body 60 is mounted at a position facing the end surface 93a that constitutes the outer peripheral surface 93 of the power storage module 1.

[0122] In this example, the stacked battery 100 further includes structure bodies 60A and 60B. The structure bodies 60A and 60B have structures and functions similar to those of the structure body 60. The length of the structure body 60A in the DR1 direction is shorter than the length of the structure body 60 in the DR1 direction. The length of the structure body 60B in the DR1 direction is longer than the length of the structure body 60 in the DR1 direction. Similar to the structure body 60, the structure bodies 60A and 60B are housed in the external body 20.

[0123] The structure body 60A is mounted on the same side as the structure body 60. Similar to the structure body 60, the structure body 60A is mounted such that the opening side faces the end surface 93a. The structure body 60B is mounted on the short edge on the opposite side to the structure body 60. The structure body 60B is mounted at a position facing the end surface 93c of the power storage module 1. Specifically, the structure body 60B is mounted such that the opening side faces the end surface 93c.

[0124] As Figure 9C shown in the state of Figure 9C , the power storage module 1 and the three structure bodies 60, 60A, and 60B are sandwiched between the first lamination part 21 and the second lamination part 22. The second lamination part 22 is in a face-down state. Then, the first lamination part 21 and the second lamination part 22 are welded to each other. As a result, the stacked battery 100 is completed as shown in the state of Figure 9D . Figure 9D shown in the state of Figure 9D .

[0125] Improved examples

[0126] In the above description, as Figure 8G and Figure 1As shown in the state of , the protective sheet 80 is provided inside the second sheet 32. However, the present invention is not limited to the above. The protective sheet 80 may be provided outside the second sheet 32.

[0127] The embodiments disclosed above are merely examples in all aspects and are in no way intended to limit the present invention. The scope of the present disclosure is defined by the scope of the claims. All modifications made within the scope and spirit equivalent to the scope and spirit of the claims are included in the present invention.

Claims

1. An electric storage device, comprising: A power storage module having a stacked electrode body in which a plurality of electrodes are stacked in a predetermined direction; and an external body, the external body accommodating the power storage module, wherein: The power storage module comprises: a main surface, a normal direction of the main surface being the predetermined direction; and an outer peripheral surface extending from the main surface in the predetermined direction; The main surface has: a plurality of first corner portions; and a plurality of edge portions, each of the plurality of edge portions being sandwiched between two of the first corner portions; The outer peripheral surface has a plurality of end surfaces continuous in the circumferential direction of the power storage module; Each of the end surfaces has a plurality of second corners, each of the plurality of second corners being connected to a different one of the first corners; The external body comprises: a laminate having a metal layer; and a plurality of protection sheets, each of the plurality of protection sheets being welded to the laminate sheet; The laminate has: a main wall portion covering each of the first corner portions and each of the edge portions; and an outer peripheral wall portion covering each of the end surfaces; and Each of the protection sheets is provided in a boundary region between the main wall portion and the peripheral wall portion in a position corresponding to the first corner portion and the plurality of second corner portions each connected to the first corner portion.

2. The power storage device according to claim 1, wherein Each of the protective sheets is a resin barrier film stronger against thermal shock than the metal layer, and is covered by the laminate sheet.

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