Battery

Abstract

The present disclosure provides a battery that has high volumetric efficiency and suppresses springback of a bent portion of a laminated film. A battery (100) according to the present disclosure has an electrode laminate (10) and a laminated film (20) that seals the electrode laminate. A laminated film in a battery according to the present disclosure has a protruding portion (20a) protruding from the periphery of an electrode laminate, and the protruding portion is bent toward the electrode laminate. In a battery according to the present disclosure, the total thickness of a first region (10a) formed at an end of an electrode laminate and a laminate film sealing the first region is smaller than the total thickness of a second region (10b), which is a region other than the first region of the electrode laminate, and a laminate film sealing the second region. Furthermore, a band-shaped member (30) is disposed in a portion of the laminated film that seals the first region in such a manner that the laminated film is wound around the band-shaped member (30) and the protruding portion is fixed.

Description

Technical Field

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

[0002] In batteries such as lithium ion secondary batteries, an electrode stack having a positive electrode collector layer, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, and a negative electrode collector layer is sometimes used. Various techniques for sealing the electrode stack are known.

[0003] For example, Patent Document 1 discloses a laminated battery, comprising a laminated structure formed by overlapping a first film and a second film, and a battery cell housed between the first film and the second film of the laminated structure, wherein the peripheral portion of the laminated structure comprises: an outer edge portion where the first film and the second film are bonded to each other, and an inner edge portion where the first film and the second film are not bonded to each other, the outer edge portion is bent more than once along the side surface of the battery cell, and the inner edge portion is bent more than once along the side surface of the battery cell.

[0004] Patent Document 2 discloses a secondary battery including an electrode assembly (electrode stack) and a heat-shrinkable protective layer that is disposed on the outer surface of the electrode assembly and shrinks due to heat.

[0005] Prior art literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-139494

[0007] Patent Document 2: U.S. Patent Application Publication No. 2018 / 0287184 Summary of the invention

[0008] In particular, the technology of Patent Document 1 still has room for improvement from the viewpoint of improving the volume efficiency of the battery and suppressing the spring back of the folded portion of the laminate film.

[0009] An object of the present disclosure is to provide a battery having high volumetric efficiency and in which springback of a bent portion of a laminate film is suppressed.

[0010] The inventors of the present disclosure have found that the above-mentioned problems can be solved by the following means.

[0011] <Scheme 1>

[0012] A battery comprising an electrode stack and a laminate film sealing the electrode stack,

[0013] The laminate film has an extension portion extending from the periphery of the electrode stack.

[0014] The extension portion is bent toward the electrode stack,

[0015] The electrode stack includes a first region formed at at least one end portion and a second region which is a region other than the first region.

[0016] The total thickness of the first region of the electrode stack and the laminate film sealing the first region is smaller than the total thickness of the second region of the electrode stack and the laminate film sealing the second region, and

[0017] The belt-shaped member is arranged so as to be wound around the laminate film and fix the extended portion at a location in the laminate film where the first region is sealed.

[0018] <Solution 2>

[0019] In the battery according to aspect 1, the laminate film has a welding layer, and the extended portion is formed by welding ends formed by welding the welding layers at the ends of the laminate film.

[0020] <Scheme 3>

[0021] According to the battery of scheme 1 or 2, the total thickness of the first region of the electrode stack, the laminate film sealing the first region and the strip-shaped member is the same as or smaller than the total thickness of the second region of the electrode stack and the laminate film sealing the second region.

[0022] <Scheme 4>

[0023] The battery according to any one of aspects 1 to 3, wherein the strip-shaped member is an adhesive tape.

[0024] <Scheme 5>

[0025] The battery according to any one of embodiments 1 to 4, wherein the electrode stack is composed of a plurality of preliminary stacks having a negative electrode collector layer, a negative electrode active material layer, an electrolyte layer, a positive electrode active material layer, and a positive electrode collector layer in this order;

[0026] The first region is a region formed because the positive electrode active material layer is smaller than the negative electrode active material layer in the surface direction.

[0027] <Scheme 6>

[0028] The battery according to any one of aspects 1 to 5, further comprising a current collector terminal electrically connected to the current collector foil of the electrode stack, wherein the laminate film seals the electrode stack together with the current collector terminal.

[0029] <Scheme 7>

[0030] A battery module comprising a plurality of stacked batteries according to any one of aspects 1 to 6.

[0031] According to the present disclosure, it is possible to provide a battery having high volumetric efficiency and in which springback of a bent portion of a laminate film is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic perspective view showing an example of the battery of the present disclosure.

[0033] Figure 2 middle, Figure 2 (a) is a cross-sectional view of the battery of the present disclosure taken along line AA, Figure 2 (b) is a cross-sectional view taken along line BB of the battery of the present disclosure.

[0034] Figure 3 It is a schematic side view showing an example of the battery of the present disclosure, in which a portion of the first region of the electrode stack is enlarged.

[0035] Figure 4 It is a schematic side view showing an example of an electrode stack in which the first region is enlarged in the battery of the present disclosure.

[0036] Figure 5 This is a schematic perspective view showing an example of a battery module of the present disclosure.

[0037] Description of Reference Numerals

[0038] 100 battery

[0039] 200 battery modules

[0040] 10-electrode stack

[0041] 10a Area 1

[0042] 10b Area 2

[0043] 20 laminated films

[0044] 20a Extension

[0045] 30 Strip components

[0046] 40 collector terminal DETAILED DESCRIPTION

[0047] Hereinafter, the embodiments of the present disclosure will be described in detail. Note that the present disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the disclosed gist.

[0048] "Battery"

[0049] The battery disclosed in the present invention comprises an electrode stack and a laminate film that seals the electrode stack. The laminate film in the battery disclosed in the present invention comprises an extension portion that extends from the periphery of the electrode stack, and the extension portion is bent toward the electrode stack. The electrode stack in the battery disclosed in the present invention comprises a first region formed at at least one end, and a second region that is a region other than the first region. In the battery disclosed in the present invention, the total thickness of the first region of the electrode stack and the laminate film that seals the first region is smaller than the total thickness of the second region of the electrode stack and the laminate film that seals the second region. In addition, in the battery disclosed in the present invention, at the portion of the laminate film that seals the first region, the strip-shaped member is arranged in such a manner that the extension portion is fixed by winding the laminate film.

[0050] When sealing the electrode stack with a laminate film, the volume efficiency of the battery can be improved by bending the extended portion of the laminate film extending from the periphery of the electrode stack toward the electrode stack. However, the extended portion after bending sometimes returns to its original state due to rebound, resulting in a problem of deterioration of the volume efficiency of the battery.

[0051] In this regard, the present inventors proposed a scheme in which, after sealing the electrode stack with a laminate film, the extended portion of the laminate film is bent toward the electrode stack, and a strip-shaped member is arranged in a first region formed at at least one end of the electrode stack and having a thickness smaller than that of the second region by winding the laminate film to fix the extended portion, thereby completing the present disclosure. As a result, it was found that the springback of the extended portion can be suppressed, and as a result, the volume efficiency of the battery can be improved.

[0052] Furthermore, if a force is applied to the film surface to bend it, a bending stress consisting of a tensile stress and a compressive stress is applied to the film. In the present disclosure, rebound means that when the force applied to the film surface is released, the film responds to the bending stress and returns to the state before bending.

[0053] Hereinafter, the battery of the present disclosure will be described with reference to the drawings. Note that the dimensional relationships (length, width, thickness, etc.) in the drawings of the present disclosure do not reflect the actual dimensional relationships.

[0054] The battery 100 of the present disclosure includes an electrode stack 10 and a laminate film 20 that seals the electrode stack 10 .

[0055] Figure 1 1 is a schematic perspective view showing an example of a battery 100 of the present disclosure. Figure 2 (a) is a cross-sectional view of the battery 100 of the present disclosure taken along line AA, and Figure 2 (b) is a cross-sectional view of the battery 100 of the present disclosure taken along line BB. Figure 1 , Figure 2 (a) and Figure 2As shown in (b) , the laminate film 20 in the battery of the present disclosure has an extended portion 20 a extending from the periphery of the electrode stack 10 , and the extended portion 20 a is bent toward the electrode stack 10 .

[0056] The extension portion 20a can be formed by welding or bonding the overlapping portions of the laminate film 20. For example, the laminate film 20 may have a welding layer, and the extension portion 20a may be formed by welding ends formed by welding the welding layers at the ends of the laminate film 20. Alternatively, the extension portion 20a may be formed by bonding with an adhesive or the like. Furthermore, the extension portion 20a may include a portion that is not welded or bonded.

[0057] The position of the extension portion 20a is not particularly limited, and may be located in the stacking direction of the electrode stack 10 or in a direction perpendicular to the stacking direction of the electrode stack 10 (see Figure 2 (b) When the extension 20a is located in a direction perpendicular to the stacking direction of the electrode stack 10, the thickness of the battery 100 can be suppressed from increasing. Therefore, when the battery 100 is overlapped and restrained, the strip member 30 described later can avoid hindering the pressure equalization (pressure uniformity).

[0058] The number of times the extension 20a is bent is not particularly limited, and may be one or more times. In the case of multiple times, the number of times the extension 20a is bent may be more than 2 times, more than 3 times, more than 4 times, or more than 5 times, and may be less than 6 times, less than 5 times, less than 4 times, less than 3 times, or less than 2 times. If the number is 1, the laminated film is easy to rebound, so it is easy to exert the effect of the present disclosure of suppressing rebound. In addition, if the number is multiple times, it is easy to exert the effect of the present disclosure of improving the volume efficiency of the battery.

[0059] The shape of the bent portion of the extension 20a is not particularly limited, and can be appropriately designed in consideration of the volumetric efficiency of the battery 100 and the pressure equalization when the battery 100 is overlapped and constrained. That is, the extension 20a can be appropriately designed in consideration of reducing the distance between the portion of the extension 20a farthest from the outer surface of the electrode stack 10 and the outer surface of the electrode stack 10, and making sure that the extension 20a does not exceed the thickness of the electrode stack 10 when the extension 20a is bent.

[0060] The electrode stack 10 in the battery 100 of the present disclosure includes a first region 10 a formed at at least one end portion and a second region 10 b which is a region other than the first region 10 a .

[0061] Figure 3 1 is a schematic side view showing an example of a battery of the present disclosure, in which a portion of the first region 10a of the electrode stack 10 is enlarged. Figure 3 As shown, the shape of the first region 10 a may be a tapered shape in which the thickness becomes thinner toward the end of the electrode stack 10 .

[0062] Furthermore, in Figure 1 , although an embodiment in which the first region 10 a is formed at one end of the electrode stack 10 is shown, the first region 10 a may be formed at both end portions of the electrode stack 10 .

[0063] Figure 4 FIG. 1 is a schematic side view showing an example of the electrode stack 10 in which the first region 10a is enlarged. Figure 4 As shown, the electrode stack 10 may be composed of a plurality of preliminary stacks 10' which sequentially have a negative electrode collector layer 11, a negative electrode active material layer 12, an electrolyte layer 13, a positive electrode active material layer 14, and a positive electrode collector layer 15. For example, in a lithium-ion secondary battery, in order to prevent lithium from precipitating into the negative electrode active material layer, the negative electrode active material layer is sometimes made larger than the positive electrode active material layer. In this case, Figure 4 The first region 10a may be formed by the negative electrode active material layer 12 being larger than the positive electrode active material layer 14 in the plane direction, that is, by the positive electrode active material layer 14 being smaller than the negative electrode active material layer 12 in the plane direction.

[0064] Furthermore, in Figure 4 In FIG. 1 , the electrode stack 10 is shown in which two layers of the preliminary stack 10 ′ are stacked, but the number of layers of the preliminary stack is not limited thereto.

[0065] like Figure 3 As shown, in the battery 100 of the present disclosure, the total thickness of the first region 10a of the electrode stack 10 and the laminate film 20 sealing the first region 10a is smaller than the total thickness of the second region 10b of the electrode stack 10 and the laminate film 20 sealing the second region 10b.

[0066] In addition, if Figure 1 to Figure 3 As shown, in the battery 100 of the present disclosure, the belt-shaped member 30 is arranged to be wound around the laminate film 20 at a location that seals the first region 10 a and fixes the extended portion 20 a .

[0067] like Figure 3 As shown, the total thickness of the first region 10a of the electrode stack 10, the laminate film 20 sealing the first region 10a, and the strip-shaped member 30 can be the same as or smaller than the total thickness of the second region 10b of the electrode stack 10 and the laminate film 20 sealing the second region 10b. By adopting such a structure, the thickness increase of the battery 100 can be suppressed, so that when a plurality of batteries 100 are overlapped and restrained, the strip-shaped member 30 can prevent the pressure equalization from being hindered.

[0068] Furthermore, when overlapping and constraining a plurality of batteries 100, the constraining pressure may be greater than 0.1 MPa, greater than 0.5 MPa, greater than 1.0 MPa, greater than 3.0 MPa, or greater than 5.0 MPa, and may be less than 30.0 MPa, less than 10.0 MPa, less than 5.0 MPa, less than 3.0 MPa, or less than 1.0 MPa.

[0069] The belt-shaped member 30 is not particularly limited as long as it can suppress the spring-back of the extended portion 20a after being bent. The belt-shaped member 30 may be, for example, an elastic member such as an adhesive tape or a rubber band.

[0070] The adhesive tape as the strip-shaped member 30 may be adhesive at the end of at least one surface, or may be adhesive on the entire surface of one surface. When the adhesive tape is adhesive only at the end of one surface, the load applied to the electrode stack 10 can be reduced. If the adhesive tape is adhesive on the entire surface of one surface, the effect of suppressing the rebound of the extension 20a of the laminate film 20 becomes higher. The strength of the material constituting the adhesive tape can be appropriately designed in consideration of the bending stress applied to the laminate film 20 after bending.

[0071] When the strip member 30 is an elastic member such as a rubber band, the inner circumference length of the closed region formed by the elastic member and the elastic modulus of the elastic member can be appropriately designed in consideration of not applying an excessive load to the electrode stack 10 .

[0072] like Figure 1 As shown, the battery 100 of the present disclosure may also have a collector terminal 40 electrically connected to the collector foil of the electrode stack 10. The laminate film 20 may also seal the electrode stack 10 and the collector terminal 40 together. Specifically, the laminate film 20 may also wind the electrode stack 10 and the collector terminal 40 and seal the electrode stack 10 and the collector terminal 40 together. In addition, the laminate film 20 may be composed of a first film and a second film. In this case, the first film and the second film may also sandwich the electrode stack 10 and the collector terminal 40 from the top and bottom of the stacking direction of the electrode stack 10, and seal the electrode stack 10 and the collector terminal 40 together.

[0073] <Electrode Laminate>

[0074] The electrode stack 10 functions as a power generation element of the battery 100. The shape of the electrode stack 10 is not particularly limited, and for example, it may have a top portion, a bottom portion opposite to the top portion, and four side portions connecting the top portion and the bottom portion. The shape of the top portion is not particularly limited, and for example, quadrilaterals such as squares, rectangles, rhombuses, trapezoids, and parallelograms can be cited. In addition, the shape of the top portion can also be a polygon other than a quadrilateral, and can also be a shape with a curve such as a circle. In addition, the shape of the bottom portion is the same as the shape of the top portion. The shape of the side portion is not particularly limited, and for example, quadrilaterals such as squares, rectangles, rhombuses, trapezoids, and parallelograms can be cited.

[0075] <Laminating film>

[0076] The laminated film 20 may have a welding layer, a metal layer and a resin layer in sequence along the thickness direction. As the material of the welding layer, for example, olefin resins such as polypropylene (PP) and polyethylene (PE) can be cited. As the material of the metal layer, for example, aluminum, aluminum alloy, and stainless steel can be cited. As the material of the resin layer, for example, polyethylene terephthalate (PET) and nylon can be cited. The thickness of the welding layer is, for example, greater than 40 μm and less than 100 μm. The thickness of the metal layer is, for example, greater than 30 μm and less than 60 μm. The thickness of the resin layer is, for example, greater than 20 μm and less than 60 μm. The thickness of the laminated film is, for example, greater than 80 μm and less than 250 μm.

[0077] <Current collector terminal>

[0078] The collector terminal 40 can be electrically connected to the collector foil. The material of the collector terminal 40 is not particularly limited as long as it has a current collecting function. For example, the same metal material as the positive electrode collector and the negative electrode collector can be used. The size and shape of the collector terminal 40 are not particularly limited.

[0079] The battery of the present disclosure may be a liquid battery or a solid battery. Furthermore, in the present disclosure, "solid battery" refers to a battery that uses at least a solid electrolyte as an electrolyte, and therefore, a solid battery may also use a combination of a solid electrolyte and a liquid electrolyte as an electrolyte. In addition, the solid battery of the present disclosure may also be an all-solid battery, that is, a battery that uses only a solid electrolyte as an electrolyte.

[0080] The battery of the present disclosure may be a lithium ion secondary battery. As the purpose of the battery, for example, a power source for a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), an electric vehicle (BEV), a gasoline vehicle, a diesel vehicle, etc. may be cited. It is particularly preferred to be used as a driving power source for a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV) or an electric vehicle (BEV). In addition, the battery in the present disclosure may be used as a power source for a mobile body (such as a railway, a ship, an airplane) other than a vehicle, and may also be used as a power source for electrical products such as an information processing device.

[0081] 《Battery Module》

[0082] Figure 5 1 is a schematic three-dimensional diagram showing an example of a battery module 200 of the present disclosure. The battery module 200 of the present disclosure has a plurality of batteries 100 of the present disclosure that are stacked. With respect to the battery 100 of the present disclosure, reference can be made to the above description regarding the battery of the present disclosure. In particular, in the battery 100 of the present disclosure, when the total thickness of the first region 10a of the electrode stack 10, the laminate film 20 that seals the first region 10a, and the strip-shaped member 30 is the same as or smaller than the total thickness of the second region 10b of the electrode stack 10 and the laminate film 20 that seals the second region 10b, the increase in the thickness of the battery 100 can be suppressed, and therefore, when the battery 100 is overlapped and constrained, the strip-shaped member 30 can be prevented from hindering the pressure equalization.

Claims

1. A battery comprising an electrode stack and a laminate film sealing the electrode stack, The laminate film has an extension portion extending from the periphery of the electrode stack. The extension portion is bent toward the electrode stack, The electrode stack includes a first region formed at at least one end portion and a second region which is a region other than the first region. The total thickness of the first region of the electrode stack and the laminate film sealing the first region is smaller than the total thickness of the second region of the electrode stack and the laminate film sealing the second region, and The belt-shaped member is arranged so as to be wound around the laminate film and fix the extended portion at a location in the laminate film where the first region is sealed.

2. The battery according to claim 1, The laminate film has a fusion bonding layer, and the extended portion is formed by a fusion bonding end portion formed by fusion bonding the fusion bonding layers at end portions of the laminate film.

3. The battery according to claim 1, The total thickness of the first region of the electrode stack, the laminate film sealing the first region, and the belt-shaped member is equal to or smaller than the total thickness of the second region of the electrode stack and the laminate film sealing the second region. The battery according to claim 1 , wherein the strip-shaped member is an adhesive tape.

5. The battery according to claim 1, The electrode stack is composed of a plurality of preliminary stacks having a negative electrode collector layer, a negative electrode active material layer, an electrolyte layer, a positive electrode active material layer and a positive electrode collector layer in this order. The first region is a region formed because the positive electrode active material layer is smaller than the negative electrode active material layer in the surface direction. 6 . The battery according to claim 1 , further comprising a current collector terminal electrically connected to the current collector foil of the electrode stack, wherein the laminate film seals the electrode stack together with the current collector terminal. 7 . A battery module comprising a plurality of stacked batteries according to claim 1 .

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