Battery

Abstract

To provide a battery which has high volume efficiency and suppresses spring-back of a portion where a laminate film is folded.SOLUTION: A battery 100 comprises an electrode laminate 10 and a laminate film 20 sealing the electrode laminate. The laminate film includes an extension part 20a extending to a circumference of the electrode laminate, and the extension part is folded toward the electrode laminate. In the battery, a total thickness of a first region 10a formed in an end of the electrode laminate and the laminate film sealing the first region is smaller than a total thickness of a second region 10b, which is a region other than the first region, of the electrode laminate and the laminate film sealing the second region. In a location where the first region is sealed in the laminate film, a belt-shaped member 30 is disposed so as to fix the extension part while being wound around the laminate film.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to batteries. [Background technology]

[0002] In batteries such as lithium ion secondary batteries, an electrode laminate having a positive electrode current collector layer, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer may be used. Various techniques for sealing this electrode laminate are known.

[0003] For example, Patent Document 1 discloses a laminated battery having a laminate member in which first and second films are superimposed, and a battery cell housed between the first and second films of the laminate member, wherein the peripheral portion of the laminate member has an outer edge where the first and second films are bonded to each other, and an inner edge where the first and second films are not bonded to each other, the outer edge is folded one or more times along the side of the battery cell, and the inner edge is folded one or more times along the side of the battery cell.

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

[0005] [Patent Document 1] JP 2016-139494 A [Patent Document 2] US Patent Application Publication No. 2018 / 0287184 Summary of the Invention [Problem to be solved by the invention]

[0006] In particular, the technology of Patent Document 1 has room for improvement in terms of suppressing springback at the folded portion of the laminate film while increasing the volumetric efficiency of the battery.

[0007] An object of the present disclosure is to provide a battery that has high volumetric efficiency and suppresses springback at the folded portion of the laminate film. [Means for solving the problem]

[0008] The present inventors have found that the above problems can be solved by the following means. <Aspect 1> A battery having an electrode stack and a laminate film sealing the electrode stack, the laminate film has an extension portion extending to a periphery of the electrode stack, The extension portion is bent toward the electrode stack, the electrode stack has a first region formed at at least one end portion and a second 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 A strip-shaped member is disposed at a portion of the laminate film that seals the first region so as to wrap the laminate film and fix the extension portion. battery. <Aspect 2> 2. The battery of claim 1, wherein the laminate film has a fusion layer, and the extension portion is formed by a fusion end portion formed by fusion layers at ends of the laminate film being fused together. <Aspect 3> The battery of aspect 1 or 2, wherein a total thickness of the first region of the electrode laminate, the laminate film sealing the first region, and the strip-shaped member is the same as or smaller than a total thickness of the second region of the electrode laminate and the laminate film sealing the second region. <Aspect 4> The battery according to any one of aspects 1 to 3, wherein the belt-shaped member is an adhesive tape. <Aspect 5> the electrode laminate is composed of a plurality of preliminary laminates each having, in this order, a negative electrode current collector layer, a negative electrode active material layer, an electrolyte layer, a positive electrode active material layer, and a positive electrode current collector layer; The battery according to any one of aspects 1 to 4, wherein the first region is a region formed because the positive electrode active material layer is smaller in a planar direction than the negative electrode active material layer. Aspect 6 The battery according to any one of aspects 1 to 5, further comprising a current collecting terminal electrically connected to a current collecting foil of the electrode laminate, wherein the laminate film encapsulates the electrode laminate together with the current collecting terminal. Aspect 7 A battery module comprising a plurality of the batteries according to any one of aspects 1 to 6 stacked together. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a battery having high volumetric efficiency and suppressing spring back at the folded portion of the laminate film. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic perspective view showing an example of a battery according to the present disclosure. [Diagram 2] FIG. 2 shows (a) a cross-sectional view of a battery according to the present disclosure taken along line AA, and (b) a cross-sectional view of a battery according to the present disclosure taken along line BB. [Diagram 3] FIG. 3 is a schematic side view showing an example of a battery according to the present disclosure, with an enlarged portion of a first region of an electrode stack. [Figure 4]FIG. 4 is a schematic side view showing an example of an electrode stack in which a first region is enlarged in the battery of the present disclosure. [Diagram 5] FIG. 5 is a schematic perspective view showing an example of a battery module according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, 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 present disclosure.

[0012] "battery" The battery of the present disclosure has an electrode laminate and a laminate film sealing the electrode laminate. The laminate film in the battery of the present disclosure has an extension extending to the periphery of the electrode laminate, and the extension is folded toward the electrode laminate. The electrode laminate in the battery of the present disclosure has 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 of the present disclosure, the total thickness of the first region of the electrode laminate and the laminate film sealing the first region is smaller than the total thickness of the second region of the electrode laminate and the laminate film sealing the second region. In the battery of the present disclosure, a strip-shaped member is arranged at a portion of the laminate film sealing the first region so as to wrap the laminate film and fix the extension.

[0013] When sealing the electrode laminate with a laminate film, the extension portion of the laminate film that extends to the periphery of the electrode laminate can be folded toward the electrode laminate to improve the volumetric efficiency of the battery. However, the folded extension portion may return to its original state due to spring back, which results in a problem of poor volumetric efficiency of the battery.

[0014] In this regard, the present inventors have come up with the idea of ​​folding the extending portion of the laminate film toward the electrode laminate after sealing the electrode laminate with the laminate film, and arranging a belt-shaped member in a first region that is formed at at least one end of the electrode laminate and has a thickness smaller than that of the second region so as to roll the laminate film and fix the extending portion, and have come to make the present disclosure. As a result, it has been found that the springback of the extending portion can be suppressed, and as a result, the volumetric efficiency of the battery can be improved.

[0015] When a force is applied to the film surface to bend it, the film is subjected to a bending stress consisting of tensile stress and compressive stress. In the present disclosure, springback means that when the force applied to the film surface is released, the film tries to return to its original state before bending in response to this bending stress.

[0016] 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.

[0017] The battery 100 of the present disclosure has an electrode stack 10 and a laminate film 20 that seals the electrode stack 10 .

[0018] Fig. 1 is a schematic perspective view showing an example of a battery 100 according to the present disclosure. Fig. 2 shows (a) a cross-sectional view of the battery 100 according to the present disclosure taken along line AA, and (b) a cross-sectional view of the battery 100 according to the present disclosure taken along line BB. As shown in Figs. 1 and 2, the laminate film 20 in the battery according to the present disclosure has an extension 20a extending to the periphery of the electrode laminate 10, and the extension 20a is folded toward the electrode laminate 10.

[0019] The extension portion 20a may be formed by fusing or adhering the overlapping portions of the laminate film 20. For example, the laminate film 20 may have a fusion layer, and the extension portion 20a may be formed by fusion end portions in which the fusion layers at the ends of the laminate film 20 are fused together. The extension portion 20a may also be formed by adhering with an adhesive or the like. The extension portion 20a may include a portion that is not fused or adhered.

[0020] The position of the extension portion 20a is not particularly limited, and may be located in the stacking direction of the electrode stack 10, in a direction perpendicular to the stacking direction of the electrode stack 10 (see FIG. 2(b)), etc. When the extension portion 20a is located in a direction perpendicular to the stacking direction of the electrode stack 10, an increase in the thickness of the battery 100 can be suppressed, and therefore, when the batteries 100 are stacked and restrained, the belt-shaped member 30 described below can be prevented from interfering with pressure equalization.

[0021] The number of times the extension portion 20a is folded is not particularly limited, but may be one or more times. In the case of multiple times, the number of times the extension portion 20a is folded may be two or more, three or more, four or more, or five or more, and may be six or less, five or less, four or less, three or less, or two or less. When the number of times is one, the laminate film is likely to spring back, so that the effect of the present disclosure of suppressing spring back is easily achieved. Also, when the number of times is multiple, the effect of the present disclosure of improving the volumetric efficiency of the battery is easily achieved.

[0022] The shape of the folded portion of the extension portion 20a is not particularly limited, but can be appropriately designed in consideration of the volumetric efficiency of the battery 100 and the uniformity of pressure when stacking and restraining the batteries 100. That is, the shape can be appropriately designed in consideration of reducing the distance between the portion of the extension portion 20a farthest from the outer surface of the electrode stack 10 and the outer surface of the electrode stack 10, and ensuring that the extension portion 20a does not exceed the thickness of the electrode stack 10 when folded.

[0023] The electrode stack 10 in the battery 100 of the present disclosure has a first region 10a formed in at least one end portion, and a second region 10b which is a region other than the first region 10a.

[0024] 3 is a schematic side view showing an example of a battery according to the present disclosure, in which a portion of the first region 10a of the electrode stack 10 is enlarged. As shown in FIG. 3, the shape of the first region 10a may be a tapered shape in which the thickness decreases toward the end of the electrode stack 10.

[0025] Although FIG. 1 shows an embodiment in which the first region 10a is formed at one end of the electrode stack 10, the first region 10a may be formed at both ends of the electrode stack 10.

[0026] FIG. 4 is a schematic side view showing an example of the electrode laminate 10 with the first region 10a enlarged. As shown in FIG. 4, the electrode laminate 10 may be composed of a plurality of preliminary laminates 10' having a negative electrode current 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 current collector layer 15 in this order. For example, in a lithium ion secondary battery, the negative electrode active material layer may be made larger than the positive electrode active material layer in order to prevent lithium from being deposited on the negative electrode active material layer. In this case, as shown in FIG. 4, the end of the electrode laminate 10 may have an inclined shape. The first region 10a may be a region formed due to the negative electrode active material layer 12 being larger in the planar direction than the positive electrode active material layer 14, that is, the positive electrode active material layer 14 being smaller in the planar direction than the negative electrode active material layer 12.

[0027] Although FIG. 4 shows the electrode laminate 10 in which two layers of the preliminary laminate 10' are laminated, the number of layers of the preliminary laminate is not limited to this.

[0028] As shown in FIG. 3, in the battery 100 of the present disclosure, the total thickness of the first region 10a of the electrode laminate 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 laminate 10 and the laminate film 20 sealing the second region 10b.

[0029] Also, as shown in Figures 1 to 3, in the battery 100 of the present disclosure, at the portion of the laminate film 20 that seals the first region 10a, a strip-shaped member 30 is arranged so as to wrap the laminate film 20 and fix the extension portion 20a.

[0030] 3, the total thickness of the first region 10a of the electrode laminate 10, the laminate film 20 sealing the first region 10a, and the strip-shaped member 30 may be equal to or smaller than the total thickness of the second region 10b of the electrode laminate 10 and the laminate film 20 sealing the second region 10b. With this configuration, an increase in the thickness of the battery 100 can be suppressed, and therefore, when a plurality of batteries 100 are stacked and restrained, the strip-shaped member 30 can be prevented from interfering with pressure uniformity.

[0031] The confining pressure when stacking and confining multiple batteries 100 may be 0.1 MPa or more, 0.5 MPa or more, 1.0 MPa or more, 3.0 MPa or more, or 5.0 MPa or more, and may be 30.0 MPa or less, 10.0 MPa or less, 5.0 MPa or less, 3.0 MPa or less, or 1.0 MPa or less.

[0032] The belt-shaped member 30 is not particularly limited as long as it can suppress the springback of the bent extension portion 20a. The belt-shaped member 30 may be, for example, an adhesive tape or an elastic member such as a rubber band.

[0033] The adhesive tape as the belt-shaped member 30 may have adhesiveness at least at the end of one side, but may have adhesiveness over the entire surface of the other side. When the adhesive tape has adhesiveness only at the end of one side, the load on the electrode laminate 10 can be reduced. When the adhesive tape has adhesiveness over the entire surface of one side, the effect of suppressing springback of the extension portion 20a of the laminate film 20 is enhanced. The strength of the material constituting the adhesive tape can be appropriately designed taking into consideration the bending stress applied to the folded laminate film 20, etc.

[0034] When the belt-shaped member 30 is an elastic member such as a rubber band, the length of the inner circumference of the closed area formed by the elastic member and the elastic modulus of the elastic member can be appropriately designed taking into consideration not to apply excessive load to the electrode stack 10, etc.

[0035] As shown in FIG. 1, the battery 100 of the present disclosure may further include a current collecting terminal 40 electrically connected to the current collecting foil of the electrode laminate 10. The laminate film 20 may seal the electrode laminate 10 together with the current collecting terminal 40. Specifically, the laminate film 20 may be formed by winding the electrode laminate 10 and the current collecting terminal 40, and may seal the electrode laminate 10 together with the current collecting terminal 40. The laminate film 20 may be composed of a first and a second film, and in this case, the first and second films may sandwich the electrode laminate 10 and the current collecting terminal 40 from above and below in the stacking direction of the electrode laminate 10, and may seal the electrode laminate 10 together with the current collecting terminal 40.

[0036] <Electrode laminate> The electrode laminate 10 functions as a power generating element of the battery 100. The shape of the electrode laminate 10 is not particularly limited, but may have, for example, a top surface portion, a bottom surface portion facing the top surface portion, and four side surfaces connecting the top surface portion and the bottom surface portion. The shape of the top surface portion is not particularly limited, but may be, for example, a quadrangle such as a square, a rectangle, a rhombus, a trapezoid, or a parallelogram. The shape of the top surface portion may be a polygon other than a quadrangle, or may be a shape having a curve such as a circle. The shape of the bottom surface portion is the same as that of the top surface portion. The shape of the side surface portion is not particularly limited, but may be, for example, a quadrangle such as a square, a rectangle, a rhombus, a trapezoid, or a parallelogram.

[0037] <Lamination film> The laminate film 20 may have a fusion layer, a metal layer, and a resin layer in this order along the thickness direction. Examples of materials for the fusion layer include olefin resins such as polypropylene (PP) and polyethylene (PE). Examples of materials for the metal layer include aluminum, aluminum alloys, and stainless steel. Examples of materials for the resin layer include polyethylene terephthalate (PET) and nylon. The thickness of the fusion layer is, for example, 40 μm or more and 100 μm or less. The thickness of the metal layer is, for example, 30 μm or more and 60 μm or less. The thickness of the resin layer is, for example, 20 μm or more and 60 μm or less. The thickness of the laminate film is, for example, 80 μm or more and 250 μm or less.

[0038] <Collector terminal> The current collecting terminal 40 may be electrically connected to the current collecting foil. The material of the current collecting terminal 40 is not particularly limited as long as it has a current collecting function, and may be, for example, the same metal material as the positive electrode current collector and the negative electrode current collector. The size, shape, etc. of the current collecting terminal 40 are not particularly limited.

[0039] The battery of the present disclosure may be a liquid battery or a solid-state battery. In the present disclosure, a "solid-state battery" refers to a battery that uses at least a solid electrolyte as an electrolyte, and therefore a solid-state battery may use a combination of a solid electrolyte and a liquid electrolyte as an electrolyte. The solid-state battery of the present disclosure may also be an all-solid-state battery, i.e., a battery that uses only a solid electrolyte as an electrolyte.

[0040] The battery of the present disclosure may be a lithium-ion secondary battery. Examples of uses of the battery include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline-powered vehicles, and diesel-powered vehicles. In particular, the battery is preferably used as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). The battery of the present disclosure may also be used as a power source for moving objects other than vehicles (e.g., railways, ships, and aircraft), and may also be used as a power source for electrical appliances such as information processing devices.

[0041] Battery module FIG. 5 is a schematic perspective view showing an example of a battery module 200 of the present disclosure. The battery module 200 of the present disclosure has a plurality of stacked batteries 100 of the present disclosure. For the battery 100 of the present disclosure, the above description of the battery of the present disclosure can be referred to. 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 sealing the first region 10a, and the strip-shaped member 30 is equal to 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, it is possible to suppress an increase in the thickness of the battery 100, and therefore, when the batteries 100 are stacked and restrained, it is possible to prevent the strip-shaped member 30 from interfering with pressure equalization. [Explanation of symbols]

[0042] 100 batteries 200 Battery Module 10 Electrode laminate 10a 1st area 10b 2nd area 20 Laminating film 20a Extension 30 Belt-shaped member 40 Current collector terminal

Claims

1. A battery having an electrode stack and a laminate film sealing the electrode stack, the laminate film has an extension portion extending to a periphery of the electrode stack, The extension portion is bent toward the electrode stack, the electrode stack has a first region formed at at least one end portion and a second region other than the first region, A total thickness of the first region of the electrode stack and the laminate film sealing the first region is smaller than a total thickness of the second region of the electrode stack and the laminate film sealing the second region, and A belt-shaped member is disposed at a portion of the laminate film that seals the first region so as to wrap the laminate film and fix the extension portion. battery.

2. The battery according to claim 1 , wherein the laminate film has a fusion layer, and the extension portion is formed by a fusion end portion formed by fusing the fusion layers at the ends of the laminate film together.

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

4. The battery according to claim 1 , wherein the strip-shaped member is an adhesive tape.

5. the electrode laminate is composed of a plurality of preliminary laminates each having, in this order, a negative electrode current collector layer, a negative electrode active material layer, an electrolyte layer, a positive electrode active material layer, and a positive electrode current collector layer; The battery according to claim 1 , wherein the first region is a region formed due to the positive electrode active material layer being smaller than the negative electrode active material layer in a planar direction.

6. The battery according to claim 1 , further comprising a current collecting terminal electrically connected to a current collecting foil of the electrode laminate, the laminate film sealing the electrode laminate together with the current collecting terminal.

7. A battery module comprising a plurality of the batteries according to any one of claims 1 to 6 stacked together.

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