Battery

Abstract

The present disclosure relates to a battery. Disclosed is a battery. The present invention is provided with: an electrode body in which a current collector foil, a positive electrode active material layer, and a negative electrode active material layer are laminated, the current collector foil having an uncoated section in which the positive electrode active material layer and the negative electrode active material layer are not coated in the lamination direction; a quadrilateral frame-shaped first sealing body disposed so as to cover a region on the end side of the current collector foil at the uncoated portion; and a quadrilateral frame-shaped second sealing body disposed so as to cover an outer surface of the first sealing body. At least a corner region of the second sealing body is configured from a material having a linear expansion coefficient of 40 * 10 <-6 > / DEG C or less.

Description

Technical Field

[0001] The present disclosure relates to a battery. Background Art

[0002] Conventionally, a battery has been used that includes an electrode body formed by stacking a collector foil, a positive electrode active material layer, and a negative electrode active material layer, a first sealing body arranged to cover an area on the end side of the collector foil at an uncoated portion, and a second sealing body arranged to cover a surface outside the first sealing body.

[0003] For example, Japanese Patent Application Laid-Open No. 2021-174632 discloses a storage module comprising an electrode stack having a plurality of stacked metal plates and a sealing body for sealing an internal space formed between two adjacent metal plates among the plurality of metal plates, the sealing body comprising a rectangular ring-shaped first sealing portion joined to a peripheral portion of the metal plates and a second sealing portion arranged around the stacked first sealing portion, the second sealing portion comprising a first resin portion arranged around the first sealing portion and a second resin portion arranged around the first resin portion, and a difference between a linear expansion coefficient of the first sealing portion and a linear expansion coefficient of the first resin portion is smaller than a difference between a linear expansion coefficient of the first sealing portion and a linear expansion coefficient of the second resin portion.

[0004] In addition, Japanese Patent Application Laid-Open No. 2019-091606 discloses a method for manufacturing a bipolar battery, which includes a first step of producing a battery structure having an electrode stack and a primary sealing portion, a second step of injecting an electrolyte into the interior of the battery structure from an injection hole of the primary sealing portion while the electrode stack is constrained by a pair of constraining plates in a manner such that the distance between a pair of constraining plates that clamp the electrode stack in the stacking direction becomes a prescribed length, a third step of discharging the electrolyte from the injection hole by constraining the electrode stack with a pair of constraining plates in a manner such that the distance between the pair of constraining plates becomes shorter than the prescribed length, and a fourth step of constraining the electrode stack with a pair of constraining plates in a manner such that the distance between the pair of constraining plates becomes the prescribed length after the third step is performed. Summary of the Invention

[0005] However, in conventional batteries, resin is generally used for the second sealant, which is arranged to cover the outer surface of the first sealant. The second sealant made of resin is susceptible to expansion and contraction due to temperature changes. In low-temperature environments, the second sealant may contract, and a force in the direction of contraction may act on the corners of the second sealant. If this contraction force is generated at the corners of the second sealant, stress is applied to the corners of the uncoated portion of the collector foil, and this stress may cause wrinkles in the uncoated portion of the collector foil.

[0006] The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a battery in which wrinkles are suppressed from occurring in uncoated portions of a current collector foil.

[0007] Technical solutions for solving the above-mentioned problems include the following.

[0008] <1> A battery having:

[0009] an electrode body including a stack of a current collector foil, a positive electrode active material layer, and a negative electrode active material layer, wherein the current collector foil has an uncoated portion in a stacking direction where the positive electrode active material layer and the negative electrode active material layer are not coated;

[0010] a first sealing body having a quadrangular frame shape, arranged so as to cover a region on an end side of the collector foil at the uncoated portion; and

[0011] The second sealing body having a quadrangular frame shape is arranged so as to cover the outer surface of the first sealing body.

[0012] At least the corner area of ​​the second sealing body has a linear expansion coefficient of 40×10 -6 / ℃ or below.

[0013] <2> The battery according to <1>,

[0014] The second sealing body as a whole is composed of a linear expansion coefficient of 40×10 -6 / ℃ or below.

[0015] <3> The battery according to <1> or <2>,

[0016] At least the corner area of ​​the first sealing body has a linear expansion coefficient of 40×10 -6 / ℃ or below.

[0017] <4> The battery according to <3>,

[0018] The first sealing body as a whole is composed of a linear expansion coefficient of 40×10 -6 / ℃ or below.

[0019] <5> The battery according to any one of <1> to <4>,

[0020] The linear expansion coefficient is 40×10 -6The material below / ℃ is at least one selected from the group consisting of glass epoxy resin, Lossna board, Miolex, Bestermo, polybutylene terephthalate, polyetheretherketone, polyamideimide, alumina, zirconium oxide, forsterite, steatite, mullite, aluminum nitride, zircon, zircon cordierite, cordierite, low-expansion cordierite, aluminum titanate, β-spodumene and ordinary porcelain.

[0021] According to the present disclosure, a battery is provided in which wrinkles are suppressed from occurring in uncoated portions of a current collector foil. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals designate like elements, and in which:

[0023] Figure 1 It is a schematic cross-sectional view illustrating the structure of a bipolar secondary battery according to an embodiment of the present disclosure.

[0024] Figure 2 This is a schematic plan view showing the vicinity of the corners of the current collector foil, the first sealing body, and the second sealing body in a conventional battery. DETAILED DESCRIPTION

[0025] Battery

[0026] The battery according to the embodiment of the present disclosure includes an electrode body formed by laminating a current collector foil, a positive electrode active material layer, and a negative electrode active material layer, a first sealing body, and a second sealing body.

[0027] The current collector foil in the electrode assembly has an uncoated portion in the stacking direction where the positive electrode active material layer and the negative electrode active material layer are not coated.

[0028] The first sealing body is arranged so as to cover the end side region of the collector foil in the uncoated portion. The first sealing body has a quadrilateral frame shape.

[0029] The second sealing body is arranged so as to cover the outer surface of the first sealing body. The second sealing body has a quadrilateral frame shape.

[0030] Furthermore, the corner region of the second sealing body (hereinafter also referred to as "corner region") is formed by a linear expansion coefficient of 40×10 -6 / ℃ or below.

[0031] In addition, in the present disclosure, regarding the "corner region" in the second sealed body, the region starting from a corner of the second sealed body having a quadrilateral shape and extending to one-tenth of the length of one side is defined as the corner region. Similarly, the "corner region" in the first sealed body is also defined as the region starting from a corner of the first sealed body having a quadrilateral shape and extending to one-tenth of the length of one side. The first sealed body and the second sealed body, each having four corners, have four corner regions starting from these corners.

[0032] A battery comprises, for example, a negative electrode, a positive electrode, a separator, and an electrolyte. The battery of the embodiments disclosed herein is suitable for use in, for example, a liquid battery having a liquid electrolyte. Liquid batteries having a non-aqueous electrolyte are particularly preferred. Alternatively, a bipolar battery may be provided, with a positive electrode active material layer and a negative electrode active material layer on both sides of a current collector that functions as both a positive electrode current collector and a negative electrode current collector.

[0033] Hereinafter, a battery according to an embodiment of the present disclosure will be described in detail using the accompanying drawings. Here, the structure of the battery according to an embodiment of the present disclosure will be described using a bipolar secondary battery as an example.

[0034] In addition, Figure 1 Here, “upper surface” means the upper side of the figure, and “lower surface” means the lower side of the figure. Figure 1 This is a schematic cross-sectional view illustrating the structure of a bipolar secondary battery, showing one power storage module 11 in the secondary battery. A secondary battery is constructed by arranging a stack of a plurality of such power storage modules 11 and conductive plates (not shown) alternately.

[0035] The battery module 11 is a rectangular, flat-plate-shaped single cell. In this embodiment, the battery module 11 is a bipolar lithium-ion secondary battery. The battery module 11 includes an electrode stack formed by stacking a plurality of bipolar electrodes 12, a plurality of first seals 20 attached to each bipolar electrode 12, and a second seal 25 attached to cover the outer surfaces of the plurality of first seals 20 (i.e., the surface of the first seal 20 opposite the electrode stack). The plurality of bipolar electrodes 12 are stacked along the thickness direction (the thickness direction in the flat plate shape), with the first seal 20 attached to each bipolar electrode 12. The second seal 25 is attached to the first seal 20 to cover the outer surfaces of the plurality of first seals 20.

[0036] The bipolar electrode 12 includes a collector foil 13, a positive electrode active material layer 14 provided on the lower surface of the collector foil 13, a negative electrode active material layer 15 provided on the upper surface of the collector foil 13, and a separator 16. The collector foil 13 is a conductive member having a quadrilateral shape when viewed from above. The collector foil 13 is a laminated foil formed by laminating multiple different metal foils. For example, a laminated foil of aluminum foil and copper foil is used as the collector foil 13. The collector foil 13 has an uncoated portion 13a in the stacking direction where the positive electrode active material layer 14 and the negative electrode active material layer 15 are not coated.

[0037] The positive electrode active material layer 14 constitutes the positive electrode of the bipolar electrode 12 and is disposed on the lower surface of the current collector foil 13 via an adhesive layer. The positive electrode active material layer 14 contains a positive electrode active material and may further contain a conductive additive, a binder, and the like.

[0038] Examples of positive electrode active materials include composite oxides, metallic lithium, and sulfur. In the composition of the composite oxide, for example, at least one of iron, manganese, titanium, nickel, cobalt, and aluminum, as well as lithium, are included. Examples of composite oxides include olivine-type lithium iron phosphate (LiFePO4), LiCoO2, and LiNiMnCoO2. Examples of binders include polyvinylidene fluoride, polytetrafluoroethylene, fluororubber, and other fluorine-containing resins, polypropylene, polyethylene, and other thermoplastic resins, polyimide, polyamide-imide, and other imide resins, alkoxysilyl-containing resins, acrylic acid or methacrylic acid, and other acrylic resins containing monomer units, styrene-butadiene rubber (SBR), carboxymethyl cellulose, sodium alginate, ammonium alginate, and other alginates, water-soluble cellulose ester crosslinked bodies, starch-acrylic acid graft polymers, and the like. These binders can be used alone or in combination. Examples of conductive additives include acetylene black, carbon black, and graphite.

[0039] The negative electrode active material layer 15 constitutes the negative electrode of the bipolar electrode 12 and is disposed on the upper surface of the current collector foil 13 .

[0040] The negative electrode active material layer 15 can include a negative electrode active material, a conductive additive, and a binder. Examples of the conductive additive and binder include those used in the positive electrode active material layer 14. Examples of the negative electrode active material include graphite, artificial graphite, highly oriented graphite, mesocarbon microbeads, hard carbon, soft carbon, and other carbons; metal compounds; elements capable of alloying with lithium or compounds thereof; and boron-doped carbon. Examples of elements capable of alloying with lithium include silicon (Si) and tin.

[0041] The separator 16 is, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains an electrolyte, and is disposed on the upper surface of the negative electrode active material layer 15 .

[0042] The positive electrode active material layer 14 and the negative electrode active material layer 15 are formed on the collector foil 13 using conventionally known methods such as roll coating, die coating, dip coating, doctor blade coating, spray coating, and curtain coating. Specifically, an active material, a solvent, and, if necessary, a binder and a conductive additive are mixed to create a slurry, which is then applied to the upper and lower surfaces of the collector foil 13 and dried. Furthermore, when forming the positive electrode active material layer 14 and the negative electrode active material layer 15 on the collector foil 13, the slurries of the positive and negative electrode active material layers are applied to form the uncoated portion 13a.

[0043] In the electrode stack, adjacent bipolar electrodes 12 in the stacking direction are stacked such that the positive electrode active material layer 14 on one side overlaps the separator 16 on the other side. Furthermore, the electrode stack includes a positive terminal electrode 17 at the upper end and a negative terminal electrode 18 at the lower end of the stack of bipolar electrodes 12 in the stacking direction. The positive terminal electrode 17 includes a collector foil 13 and a positive electrode active material layer 14 provided on the lower surface of the collector foil 13. The positive electrode active material layer 14 is stacked on the adjacent bipolar electrode 12, with the collector foil 13 stacked on its upper surface. The negative terminal electrode 18 includes a collector foil 13 and a negative electrode active material layer 15 provided on the upper surface of the collector foil 13, and a separator 16 stacked on its upper surface. The separator 16 is stacked on the adjacent bipolar electrode 12, with the negative electrode active material layer 15 stacked on its lower surface, and the collector foil 13 stacked on its lower surface. The positive terminal electrode 17 and the negative terminal electrode 18 are respectively stacked on the conductive plates adjacent to the current collector foil 13 .

[0044] The first sealing body 20 is a rectangular, frame-like component placed at the outer peripheral end of the bipolar electrode 12. The first sealing body 20 seals the bipolar electrode 12. This seals the bipolar electrodes 12 adjacent to each other in the stacking direction. The first sealing body 20 includes a first sealing member 21, a second sealing member 22, and a spacer 23.

[0045] The first sealing member 21 is a quadrilateral, frame-shaped member that is arranged along the outer peripheral end (outer edge) of the bipolar electrode 12. Specifically, the first sealing member 21 is arranged at the outer peripheral end of the bipolar electrode 12 and joined between the upper surface of the collector foil 13 and the lower surface of the separator 16, thereby arranging the negative electrode active material layer 15 within its frame. A predetermined gap is provided between the inner edge of the first sealing member 21 and the negative electrode active material layer 15 to form a space. On the other hand, the outer edge of the first sealing member 21 is configured so that the first sealing member 21 protrudes outward from the collector foil 13.

[0046] The second sealing component 22 is a quadrilateral and frame-shaped component, which is arranged along the outer peripheral end (outer edge) of the bipolar electrode 12. Specifically, the second sealing component 22 is arranged at the outer peripheral end of the bipolar electrode 12 and joined between the lower surface of the collector foil 13 and the upper surface of the separator 23, and the positive electrode active material layer 14 is arranged together with the separator 23 in its frame. A predetermined interval is set between the inner edge of the second sealing component 22 and the positive electrode active material layer 14 to form a space. On the other hand, the outer edge of the second sealing component 22 is constructed in a manner that the second sealing component 22 protrudes outward from the collector foil 13, and the upper surface of the second sealing component 22 is joined to the lower surface of the first sealing component 21. In this way, the area on the end side of the collector foil 13 at the uncoated portion 13a is covered by the first sealing component 21 and the second sealing component 22.

[0047] The separator 23 is a quadrilateral, frame-shaped member that is positioned along the outer peripheral end of the bipolar electrode 12. Specifically, the separator 23 is combined with the second sealing member 22 to be positioned at the outer peripheral end of the bipolar electrode 12 and bonded between the lower surface of the second sealing member 22 and the upper surface of the separator 16 of the adjacent bipolar electrode 12, thereby positioning the positive electrode active material layer 14 within its frame. The inner edge of the separator 23 is positioned separately from the positive electrode active material layer 14. On the other hand, the outer edge of the separator 23 is configured so that the separator 23 protrudes outward from the separator 16, and its lower surface is bonded to the upper surface of the first sealing member 21 of the adjacent first sealing body 20.

[0048] The second sealing body 25 is a rectangular frame-shaped member arranged along the outer peripheral ends of the plurality of first sealing bodies 20. The second sealing body 25 frames the first sealing bodies 20 and the bipolar electrodes 12. The inner edge of the second sealing body 25 is arranged so as to cover the outer surface of the first sealing body 20.

[0049] The second sealing body 25 as a whole has a linear expansion coefficient of 40×10 -6 / ℃ or less (hereinafter referred to as "low expansion material"). In addition, the first sealing member 21, the second sealing member 22 and the spacer 23 constituting the first sealing body 20 are also made of a material with a linear expansion coefficient of 40×10 -6 / ℃ or below (low expansion material).

[0050] Here, a conventional battery will be described. Figure 2 This is a schematic plan view showing the vicinity of the corners of the current collector foil, the first sealing body, and the second sealing body in a conventional battery.

[0051] In conventional batteries, a quadrangular frame-shaped first sealing member 200 is arranged to cover the end area of ​​the collector foil 130 at the uncoated portion 130a, and a quadrangular frame-shaped second sealing member 250 is further arranged to cover the outer surface of the first sealing member 200. For example, resin is used for the second sealing member 250. Therefore, as Figure 2 As shown, the second sealing body 250 is susceptible to expansion and contraction due to temperature changes. In low-temperature environments, the second sealing body 250 may contract, generating forces in the directions of arrows Y1 and Y2 at the corners of the second sealing body 250. When forces in the directions of arrows Y1 and Y2 are generated at the corners of the second sealing body 250, stress is applied to a corner Z1 of the uncoated portion 130a of the collector foil 130. As a result, wrinkles may form at the corner Z1 of the uncoated portion 130a of the collector foil 130. If the wrinkles become more pronounced, they may lead to breakage.

[0052] Furthermore, in some batteries, no components other than the collector foil 130 and separator (not shown) are present in the uncoated portion 130a of the collector foil 130 in the stacking direction. In batteries with this structure, the moment of inertia is reduced, and the weight of the collector foil 130 may cause buckling (significant deflection of the collector foil 130) at location X1 of the uncoated portion 130a. Furthermore, if buckling of the uncoated portion 130a of the collector foil 130 further develops the aforementioned wrinkles at location Z1, the buckling and wrinkles may combine to further increase the likelihood of fracture of the collector foil 130.

[0053] In contrast, in the battery according to the embodiment of the present disclosure, at least the corner region of the second sealing body is formed by a linear expansion coefficient of 40×10 -6 / ℃ or less material (low expansion material). Therefore, in the corner area of ​​the second seal, the expansion and contraction caused by temperature changes are suppressed. Therefore, in a low temperature environment, the corner area of ​​the second seal is also suppressed. Figure 2 As a result, the corners of the uncoated portion of the collector foil (specifically, Figure 2 Wrinkles are formed at the portion Z1 shown, and further, the occurrence of breakage due to the wrinkles becoming noticeable is suppressed.

[0054] also, Figure 1The second sealing body 25 shown is entirely made of a low-expansion material, but the battery of the embodiment of the present disclosure is not limited to this structure. At least the corner region (i.e., the region starting from the corner of the second sealing body and extending to one tenth of the length of one side) may be made of a low-expansion material. Since the corner region of the second sealing body is made of a low-expansion material, the occurrence of heat generation in the corner region of the second sealing body is suppressed even in a low-temperature environment. Figure 2 As a result, the generation of wrinkles at the corners of the uncoated portion of the collector foil is suppressed, and further, the generation of cracks is suppressed.

[0055] However, if Figure 1 As shown, it is preferred that the second sealing body 25 is entirely made of a low expansion material. Since the second sealing body is entirely made of a low expansion material, the force generated in the corner area of ​​the second sealing body is also suppressed in a low temperature environment ( Figure 2 The forces in the directions of arrows Y1 and Y2 shown in FIG. 1 ) can more easily suppress the generation of wrinkles at the corners of the uncoated portion of the collector foil.

[0056] In addition, in the first sealing body ( Figure 1 In the first sealing member 21, the second sealing member 22, and the spacer 23 constituting the first sealing member 20, it is preferred that at least the corner region (i.e., the region starting from the corner of the first sealing member and extending to one tenth of the length of one side) be made of a low expansion material. In conventional batteries, resin is generally also used for the first sealing member. In a low temperature environment, the first sealing member may shrink, and stress may be applied to the corner of the uncoated portion of the collector foil (specifically, Figure 2 Therefore, since the corner regions of the first seal are made of a low-expansion material, even in a low-temperature environment, forces generated in the corner regions of the first seal are suppressed, making it easier to suppress wrinkles at the corners of the uncoated portion of the collector foil.

[0057] Furthermore, if Figure 1 As shown, it is more preferable that the first sealing body 20 is entirely made of a low expansion material. Since the first sealing body is entirely made of a low expansion material, the force generated in the corner area of ​​the first sealing body is also suppressed in a low temperature environment ( Figure 2 The forces in the directions of arrows Y1 and Y2 shown in FIG. 1 ) can more easily suppress the generation of wrinkles at the corners of the uncoated portion of the collector foil.

[0058] As the linear expansion coefficient is 40×10 -6 / ℃ or below materials (low expansion materials), for example, at least one material selected from the group consisting of glass epoxy resin, Lossna board, Miolex, Bestermo, polybutylene terephthalate, polyetheretherketone, polyamideimide, alumina, zirconium oxide, forsterite, steatite, mullite, aluminum nitride, zircon, zircon cordierite, cordierite, low expansion cordierite, aluminum titanate, β-spodumene and ordinary porcelain.

[0059] These materials have, for example, the following linear expansion coefficients.

[0060] Glass epoxy resin: 21×10 -6 / ℃ below

[0061] Lossna Board: 26×10 -6 / ℃ below

[0062] Miolex: 23×10 -6 / ℃ below

[0063] Besthermo: 40×10 -6 / ℃ below

[0064] Polybutylene terephthalate: 15×10 -6 / ℃ below

[0065] PEEK: 25×10 -6 / ℃ below

[0066] Polyamide-imide: 30.6×10 -6 / ℃ below

[0067] Alumina: 8×10 -6 / ℃ below

[0068] Zirconia: 10×10 -6 / ℃ below

[0069] Forsterite: 10×10 -6 / ℃ below

[0070] Talc: 8×10 -6 / ℃ below

[0071] Mullite: 5×10 -6 / ℃ below

[0072] Aluminum nitride: 5×10 -6 / ℃ below

[0073] Zircon: 4×10 -6 / ℃ below

[0074] Zircon Iolite: 4×10 -6 / ℃ below

[0075] Iolite: 3×10 -6 / ℃ below

[0076] Low expansion cordierite: 1×10 -6 / ℃ below

[0077] Aluminum titanate: 1×10 -6 / ℃ below

[0078] β-spodumene: 1×10 -6 / ℃ below

[0079] Ordinary porcelain: 7×10 -6 / ℃ below

[0080] Furthermore, the linear expansion coefficient of the material constituting the first sealing body and the second sealing body is measured by thermomechanical analysis (TMA). For example, the linear expansion coefficient of plastics can be measured according to JIS K7197 (2012, Test method for linear expansion coefficient of plastics by thermomechanical analysis), and the linear expansion coefficient of fine ceramics can be measured according to JIS R1618 (2002, Determination of thermal expansion of fine ceramics by thermomechanical analysis).

[0081] Examples of applications of the battery according to the embodiment of the present disclosure include power sources for hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), and battery electric vehicles (BEV).

Claims

1. A battery having: an electrode body including a current collector foil, a positive electrode active material layer, and a negative electrode active material layer stacked together, the current collector foil having an uncoated portion in a stacking direction where the positive electrode active material layer and the negative electrode active material layer are not coated; a first sealing body having a quadrangular frame shape, arranged so as to cover the end side region of the collector foil at the uncoated portion; as well as The second sealing body having a quadrangular frame shape is arranged so as to cover the outer surface of the first sealing body. At least the corner area of ​​the second sealing body has a linear expansion coefficient of 40×10 -6 / ℃ or below.

2. The battery according to claim 1, wherein The second sealing body as a whole is composed of a linear expansion coefficient of 40×10 -6 / ℃ or below.

3. The battery according to claim 1, characterized in that At least the corner area of ​​the first sealing body has a linear expansion coefficient of 40×10 -6 / ℃ or below.

4. The battery according to claim 3, wherein The first sealing body as a whole is composed of a linear expansion coefficient of 40×10 -6 / ℃ or below.

5. The battery according to claim 1, wherein The linear expansion coefficient is 40×10 -6 The material below / ℃ is at least one selected from the group consisting of glass epoxy resin, Lossna board, Miolex, Bestermo, polybutylene terephthalate, polyetheretherketone, polyamideimide, alumina, zirconium oxide, forsterite, steatite, mullite, aluminum nitride, zircon, zircon cordierite, cordierite, low-expansion cordierite, aluminum titanate, β-spodumene and ordinary porcelain.

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