Battery

Abstract

To provide a battery that suppresses the occurrence of a welding defect at a welded portion.SOLUTION: A battery according to the present disclosure includes an electrode body, a current collector terminal arranged on the side surface of the electrode body, and a laminate film covering the electrode body, and when the battery is viewed from the side from the above current collector terminal side, the outer edge of the current collector terminal is located inside the outer edge of the electrode body, the laminate film is arranged to cover a surface forming the outer edge of the current collector terminal and a surface forming the outer edge of the electrode body, a welded portion where the inner surfaces of the laminate film are welded to each other is arranged at a corner of the current collector terminal, the laminate film has at least a metal layer, in the welded portion, a first resin layer is arranged between the opposing metal layers, and a second resin layer is arranged between the metal layer and the current collector terminal, and when the thickness of the first resin layer is Ta and the thickness of the second resin layer is Tb, Ta and Tb satisfy 0.25≤Ta / Tb.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] Batteries such as lithium ion secondary batteries usually include an electrode body having a positive electrode current collector, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, and a negative electrode current collector. The electrode body is sealed in an internal space surrounded by an exterior material, for example. Patent Document 1 discloses a lithium polymer secondary battery including an electrode assembly, an exterior material surrounding the outside of the electrode assembly, and first and second covers sealing the exterior material, in which the first electrode terminal and the second electrode terminal are drawn out to the outside through the first cover and the second cover, respectively. Patent Document 1 also discloses a laminate film as the exterior material. Patent Document 2 discloses a battery using an exterior body made of one film, in which a rib structure is provided at the corner of the side perpendicular to the end face on which the current collecting tab lead is extended, in which a plurality of the above films are stacked. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-108623 A [Patent Document 2] Patent Publication No. 2021-190281 Summary of the Invention [Problem to be solved by the invention]

[0004] As shown in FIG. 3 described later, the dimensions of the current collecting terminal may be smaller than the dimensions of the electrode body. If a current collecting terminal having such a dimensional relationship is sealed with a laminate film, wrinkles may occur in the laminate film, for example, and the sealing performance of the battery may be reduced. In order to solve such a problem, the inventors came up with the idea of ​​providing a welded portion on the current collecting terminal, in which the inner faces of the laminate film are welded together. By providing the welded portion, the deterioration of the sealing performance can be suppressed. Furthermore, the welded portion is often provided at the corner of the current collecting terminal in the manufacturing process. From the viewpoint of suppressing the deterioration of the sealing performance, it is desirable to suppress the occurrence of poor welding at the welded portion.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and has as its main object to provide a battery in which the occurrence of welding defects at welded parts is suppressed. [Means for solving the problem]

[0006] [1] A battery comprising an electrode body, a current collecting terminal arranged on a side portion of the electrode body, and a laminate film covering the electrode body, wherein when the battery is viewed from the side of the current collecting terminal, an outer edge of the current collecting terminal is located inside the outer edge of the electrode body, the laminate film is arranged so as to cover a surface constituting the outer edge of the current collecting terminal and a surface constituting the outer edge of the electrode body, a welded portion in which inner surfaces of the laminate film are welded to each other is arranged at a corner of the current collecting terminal, the laminate film has at least a metal layer, a first resin layer is arranged between the opposing metal layers in the welded portion, and a second resin layer is arranged between the metal layer and the current collecting terminal, and a thickness of the first resin layer is set to T a The thickness of the second resin layer is T b In this case, the above T a and the above T b 0.25≦T a / T b Charge your batteries.

[0007] [2] The thickness of the metal layer at the welded portion is T c In this case, the above Ta and the above T c 0.5≦T a / T c The battery according to [1], which satisfies ≦4.

[0008] [3] The battery according to [1] or [2], wherein the laminate film has an inner resin layer on the surface of the metal layer facing the current collecting terminal, and the first resin layer and the second resin layer each include the inner resin layer.

[0009] [4] The battery according to [3], wherein a resin film is disposed between the inner resin layer and the current collecting terminal, and the first resin layer includes the resin film. Effect of the Invention

[0010] The battery according to the present disclosure has an effect of suppressing the occurrence of welding defects at the welded parts. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a schematic perspective view illustrating an electrode body and a current collecting terminal according to the present disclosure. [Diagram 2] FIG. 2 is a schematic perspective view illustrating an electrode body, a current collecting terminal, and a laminate film according to the present disclosure. [Diagram 3] 1A and 1B are a schematic side view and a schematic cross-sectional view illustrating an electrode body, a current collecting terminal, and a laminate film according to the present disclosure. [Figure 4] FIG. 2 is a schematic side view illustrating a portion of a battery in the present disclosure. [Diagram 5] FIG. 2 is a schematic side view illustrating a portion of a battery in the present disclosure. [Figure 6] FIG. 2 is a schematic side view illustrating a portion of a battery in the present disclosure. [Figure 7] FIG. 2 is a schematic plan view illustrating a portion of a battery according to the present disclosure. [Figure 8] FIG. 1 is a schematic perspective view illustrating a portion of a battery according to the present disclosure. [Figure 9] FIG. 2 is a schematic side view illustrating a portion of a battery in the present disclosure. [Figure 10] 1A to 1C are schematic side views illustrating a method for forming protrusions on a resin film in the present disclosure. [Figure 11] 1 is a schematic cross-sectional view illustrating an electrode body according to the present disclosure. [Figure 12] FIG. 2 is a schematic side view illustrating a second coating step in the present disclosure. [Figure 13] 4 shows the results of a thermal shock test on the battery obtained in the example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. Each of the drawings shown below is a schematic illustration, and the size and shape of each part are appropriately exaggerated to facilitate understanding. In addition, in this specification, when expressing an aspect in which another member is arranged relative to a certain member, the term "above" or "below" is used, unless otherwise specified, it includes both a case in which another member is arranged directly above or below a certain member so as to be in contact with the certain member, and a case in which another member is arranged above or below a certain member via another member.

[0013] A.Battery FIG. 1 is a schematic perspective view illustrating an electrode body and a current collecting terminal in the present disclosure. The electrode body 10 shown in FIG. 1(a) has a top surface portion 11, a bottom surface portion 12 facing the top surface portion 11, and four side surfaces (a first side surface portion 13, a second side surface portion 14, a third side surface portion 15, and a fourth side surface portion 16) connecting the top surface portion 11 and the bottom surface portion 12. In FIG. 1(b), a first current collecting terminal 20A is disposed on the first side surface portion 13 of the electrode body 10, and a second current collecting terminal 20B is disposed on the third side surface portion 15 of the electrode body 10. For example, the first current collecting terminal 20A is a positive electrode current collecting terminal, and the second current collecting terminal 20B is a negative electrode current collecting terminal.

[0014] 2 is a schematic perspective view illustrating an electrode body, a current collecting terminal, and a laminate film according to the present disclosure. As shown in FIG. 2(a), the laminate film 30 is, for example, a single film. As shown in FIGS. 2(a) and 2(b), the laminate film 30 is folded so as to entirely cover the bottom surface portion 12, the second side surface portion 14, the top surface portion 11, and the fourth side surface portion 16 of the electrode body 10. Meanwhile, in FIG. 2(b), at least a part of the first current collecting terminal 20A and at least a part of the second current collecting terminal 20B are located inside the folded laminate film 30.

[0015] Fig. 3(a) is a schematic side view illustrating an electrode body and a current collecting terminal in the present disclosure, and Fig. 3(b) is a cross-sectional view taken along line AA of Fig. 3(a). As shown in Figs. 3(a) and (b), when the electrode body 10 and the current collecting terminal 20 are observed from the current collecting terminal 20 side, the outer edge E2 of the current collecting terminal 20 is located inside the outer edge E1 of the electrode body 10. In other words, the dimensions of the current collecting terminal 20 are smaller than the dimensions of the electrode body 10. Also, as shown in Fig. 3(b), the electrode body 10 has a side surface SS 10 The current collecting tab T is connected to the surface of the current collecting terminal 20 (the side surface SS of the electrode body 10). 10 The two surfaces are joined together (the surface facing the other surface).

[0016] FIG. 3(c) is a schematic side view illustrating the electrode body, the current collecting terminal, and the laminate film in the present disclosure, and FIG. 3(d) is a cross-sectional view taken along the line AA in FIG. 3(c). As shown in FIGS. 3(c) and (d), when the electrode body 10, the current collecting terminal 20, and the laminate film 30 are observed from the current collecting terminal 20 side, a space S is generated between the laminate film 30 and the current collecting terminal 20. Therefore, when the current collecting terminal 20 is sealed with the laminate film 30, wrinkles may occur in the laminate film 30 due to the excess part of the laminate film 30, and the sealing property of the battery may be reduced. In contrast, in the battery in the present disclosure, as shown in FIGS. 4(a) and (b), a welding part X is disposed at the corner of the current collecting terminal 20, where the inner surfaces (surfaces on the current collecting terminal 20 side) of the laminate film 30 are welded together. By providing the welding part X, the deterioration of the sealing property due to the wrinkles of the laminate film can be suppressed.

[0017] The laminate film 30 shown in FIG. 5 has a metal layer 31, an inner resin layer 32 arranged on the surface of the metal layer 31 facing the current collector terminal 20, and an outer resin layer 33 arranged on the surface of the metal layer 31 opposite the current collector terminal 20. In addition, a first resin layer R1 is arranged between the opposing metal layers 31 at the welded portion X. In addition, a second resin layer R2 is arranged between the metal layer 31 and the current collector terminal 20. In FIG. 5, the first resin layer R1 and the second resin layer R2 are each the inner resin layer 32 in the laminate film 30. In addition, the first resin layer R1 and the second resin layer R2 are continuously arranged. As shown in FIG. 5, the thickness of the first resin layer R1 is set to T a The thickness of the second resin layer R2 is T b In this case, T a and T b 0.25≦T a / T b Meet the following.

[0018] According to the present disclosure, since the welding portion is disposed on the current collecting terminal, the battery is one in which the deterioration of the sealing property is suppressed. As shown in FIG. 3 described above, the dimensions of the current collecting terminal may be made smaller than the dimensions of the electrode body. By adopting such a dimensional relationship, for example, when a plurality of batteries are stacked, it is possible to prevent adjacent current collecting terminals from contacting each other. By preventing the contact of adjacent current collecting terminals, the battery is less likely to be damaged. In addition, if the current collecting terminals having such a dimensional relationship are sealed with a laminate film, wrinkles may occur in the laminate film, for example, and the sealing property of the battery may be reduced. In the present disclosure, by disposing the welding portion X, in which the inner faces of the laminate film are welded to each other, on the current collecting terminal, the battery is one in which the deterioration of the sealing property is suppressed even if the dimensions of the current collecting terminal are made smaller than the dimensions of the electrode body. On the other hand, as described above, the welding portion is often provided at the corner of the current collecting terminal in the manufacturing process. From the viewpoint of suppressing the deterioration of the sealing property, it is desired to suppress the occurrence of welding defects at the welding portion. In response to this, according to the present disclosure, a T b By making it larger, the adhesion at the welded portion is improved, and the occurrence of poor welding at the welded portion can be suppressed.

[0019] 1. Battery configuration The battery according to the present disclosure includes at least an electrode body, a current collecting terminal, and a laminate film.

[0020] (1) Electrode body The electrode body in the present disclosure functions as a power generating element of a battery. The shape of the electrode body is not particularly limited, but for example, as shown in FIG. 1(a), the electrode body has a top surface portion 11, a bottom surface portion 12 facing the top surface portion 11, and four side surfaces (a first side surface portion 13, a second side surface portion 14, a third side surface portion 15, and a fourth side surface portion 16) connecting the top surface portion 11 and the bottom surface portion 12. The top surface portion 11 and the bottom surface portion 12 both correspond to the main surface of the electrode body, and the normal direction of the main surface can be defined as the thickness direction. In addition, the first side surface portion 13 and the third side surface portion 15 are arranged to face each other. Similarly, the second side surface portion 14 and the fourth side surface portion 16 are arranged to face each other.

[0021] The shape of the top surface portion is not particularly limited, but examples thereof include quadrilaterals such as a square, a rectangle, a rhombus, a trapezoid, and a parallelogram. The shape of the top surface portion 11 in FIG. 1(a) is a rectangle. The shape of the top surface portion may be a polygon other than a quadrilateral, 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 examples thereof include quadrilaterals such as a square, a rectangle, a rhombus, a trapezoid, and a parallelogram.

[0022] (2) Current collector terminal The current collecting terminals in the present disclosure are disposed on the side surfaces of the electrode body. The battery in the present disclosure preferably includes two current collecting terminals for one electrode body. For example, as shown in FIG. 1(b), a pair of current collecting terminals 20 (a first current collecting terminal 20A and a second current collecting terminal 20B) may be disposed to face each other with respect to the electrode body 10. Also, in FIG. 1(b), the pair of current collecting terminals 20 are disposed to face each other in the longitudinal direction of the electrode body 10.

[0023] When the battery is viewed from the side of the collector terminal, the shape of the collector terminal is not particularly limited, but examples thereof include quadrilaterals such as a square, a rectangle, a rhombus, a trapezoid, and a parallelogram. The shape of the collector terminal 20 in FIG. 3(a) is a rectangle. In this rectangle, the thickness direction D T The short side extends along a direction parallel to the thickness direction D T The long side extends along a direction perpendicular to the

[0024] When the battery is viewed from the side of the current collecting terminal, the outer edge of the current collecting terminal is located inside the outer edge of the electrode body. For example, as shown in Fig. 3(a), the outer edge E2 of the current collecting terminal 20 is located inside the outer edge E1 of the electrode body 10. In other words, the outer edge E2 of the current collecting terminal 20 is included in the outer edge E1 of the electrode body 10 over its entire circumference.

[0025] For example, in FIG. 3(a), the length (total circumferential length) of the outer edge E1 of the electrode body 10 is L1, and the length (total circumferential length) of the outer edge E2 of the current collecting terminal 20 is L2. The ratio of L2 to L1 (L2 / L1) may be, for example, 0.7 or more and less than 1, or 0.8 or more and 0.95 or less. T The length of the outer edge E1 at L a and the thickness direction D T The length of the outer edge E2 at L b Let us assume that L a L for b Percentage of (L b / L a ) may be, for example, 0.5 or more and less than 1, or 0.8 or more and 0.95 or less. T The length of the outer edge E1 in the direction perpendicular to L c and the thickness direction D T The length of the outer edge E2 in the direction perpendicular to L d Let us assume that L c L for d Percentage of (L d / L c) may be, for example, 0.5 or more and less than 1, or 0.8 or more and 0.95 or less. Also, for example, in FIG. 3(a), the length of the gap between the outer edge E1 and the outer edge E2 is δ. δ is greater than 0 mm, and may be 0.3 mm or more, or 0.5 mm or more. On the other hand, δ is, for example, 1.5 mm or less.

[0026] (3) Laminate film The laminate film in the present disclosure covers the electrode body and seals the electrode body together with the current collecting terminal. As shown in FIG. 2, when the electrode body 10 and the current collecting terminal 20 are observed from the current collecting terminal 20 side, the laminate film 30 is arranged so as to cover the surface constituting the above-mentioned outer edge of the current collecting terminal 20 and the surface constituting the above-mentioned outer edge of the electrode body 10. Also, as shown in FIG. 4(a), a welding part X where the inner faces of the laminate film 30 are welded together is arranged at the corner of the current collecting terminal 20. It is preferable that the welding surface at the welding part X does not have a gap. The laminate film may have one welding part X, or may have two or more welding parts X. Also, the welding part X may be arranged at each of two corners of the current collecting terminal that face each other in the thickness direction. Also, in FIG. 4(a), an end adhesion part Y where the ends of the laminate film 30 are welded together is arranged. The end adhesion part Y may be bent according to the shape of the current collecting terminal. This is because it is possible to reduce excess space. Also, as shown in Fig. 4(b), the shape of the current collecting terminal 20 may be a rectangle, and the welded portion X may be disposed at each of the corners. In Fig. 4(b), the end contact portion Y is disposed on the side connecting two corners.

[0027] As shown in FIG. 6, the welded portion X is a And the second side S b And, the first side S a and the second surface S b The surface S that connects c The second surface S b is the first surface S a and in the thickness direction D of the battery T In the first surface S a It is located on the outer side. Also, the first surface Sa Normal direction of and second surface S b The normal direction of is the thickness direction of the battery D T "Parallel" means that the angle between them is 20° or less.

[0028] In Fig. 6, when the battery is viewed from the side of the current collecting terminal 20, the welded portion X is disposed at a corner t that constitutes the outer edge E2 of the current collecting terminal 20. Also, as shown in Fig. 6, the width of the welded portion X is w1. The width w1 is, for example, 0.1 mm or more, and may be 0.3 mm or more, or may be 0.6 mm or more. On the other hand, the width w1 is, for example, 2 mm or less, and may be 1.5 mm or less.

[0029] As shown in Figs. 7 and 8, when the battery is viewed in plan from the thickness direction, the end position of the laminate film 30 on the side of the current collector terminal 20 is α, and the position of the laminate film 30 corresponding to the boundary between the current collector terminal 20 and the electrode body 10 is β. The welded portion X in Figs. 7 and 8 is continuously disposed from the end position α to the position β. In addition, when the direction (axial direction) in which the current collector terminal 20 extends from the electrode body 30 is D1, it is preferable that the welded portion X is disposed along D1. In addition, the welded portion X may be disposed in at least a part of the region from the end position α to the position β in D1. The length of the welded portion X in D1 is, for example, 1 mm or more, may be 3 mm or more, or may be 5 mm or more.

[0030] As shown in FIG. 5, the laminate film 30 has at least a metal layer 31. The laminate film 30 preferably has an inner resin layer 32 on the surface of the metal layer 31 facing the current collecting terminal 20. The laminate film 30 preferably has an outer resin layer 33 on the surface of the metal layer 31 opposite the current collecting terminal 20. In the welded portion X, a first resin layer R1 is disposed between the opposing metal layers 31. In addition, a second resin layer R2 is disposed between the metal layer 31 and the current collecting terminal 20. As shown in FIG. 5, the thickness of the first resin layer R1 is set to T a The thickness of the second resin layer R2 is T b Let us assume that T aand T b 0.25≦T a / T b Satisfy. T a / T b may be 0.5 or more, 0.75 or more, 1.0 or more, 1.1 or more, or 1.2 or more. a / T b For example, T is less than 2.0 and may be 1.8 or less. a and T b Each of T is preferably an average value of thicknesses measured at multiple points. a and T b The value of can be controlled by appropriately adjusting the conditions for covering the current collecting terminal with the laminate film.

[0031] As shown in FIG. 5, the thickness of the metal layer 31 at the welded portion X is T c Let us assume that T a and T c 0.5≦T a / T c It is preferable that T≦7 is satisfied because this can suppress damage to the welded portion X due to thermal shock. When a thermal shock is applied to the battery, the first resin layer at the welded portion X expands more than the metal layer, so that T a / T c If T is too large, the metal layer may be damaged due to the stress caused by expansion. a / T c By keeping T to 7 or less, damage to the welded part X due to thermal shock can be suppressed. a / T c If the thickness is too small, good sealing may not be obtained. a / T c may be 0.75 or more, or 1.0 or more. a / T c may be 4.0 or less, or may be 3.5 or less. a / T c When T is 4.0 or less, damage to the welded portion X due to thermal shock is significantly suppressed. cis preferably the average value of thicknesses measured at multiple points. c The value of is basically not affected by the conditions for covering the current collecting terminal with the laminate film.

[0032] 9(a), a resin film 40 may be disposed between the inner resin layer 32 of the laminate film 30 and the current collecting terminal 20. By disposing the resin film 40, the adhesion between the laminate film 30 and the current collecting terminal 20 is improved. In FIG. 9(a), the first resin layer R1 includes the inner resin layer 32 but does not include the resin film 40. In contrast, the second resin layer R2 includes the inner resin layer 32 and the resin film 40.

[0033] As shown in FIG. 9(b), the first resin layer R1 may include both the inner resin layer 32 and the resin film 40. That is, the welded portion X may include a protrusion of the resin film 40. By forming the welded portion X so as to cover the protrusion of the resin film 40, it is possible to prevent the occurrence of a gap in the welded portion X. The protrusion X may have a third surface, a fourth surface, and a curved surface connecting the third surface and the fourth surface. The fourth surface faces the third surface and is oriented in the thickness direction D of the battery. T In addition, the normal direction of the third surface and the normal direction of the fourth surface are in the thickness direction D of the battery. T 9(b), the width of the welded portion X is w1, and the width of the protrusion of the resin film 40 is w2. The ratio of the width w2 to the width w1 (w2 / w1) is, for example, 0.1 or more, may be 0.3 or more, or may be 0.5 or more. On the other hand, w2 / w1 is, for example, 0.9 or less. The preferred numerical value of the width w1 is as described above. On the other hand, the width w2 is, for example, 0.1 mm or more, may be 0.2 mm or more, or may be 0.5 mm or more. On the other hand, the width w2 is, for example, 1.9 mm or less.

[0034] Fig. 10 is a schematic side view illustrating a method for forming protrusions on a resin film in the present disclosure. As shown in Fig. 10(a), a resin film 40 is arranged around the current collecting terminal 20. At this time, in order to form protrusions, the length of the outer edge of the resin film 40 is made longer than the length of the outer edge of the current collecting terminal 20. Next, as shown in Fig. 10(b), jigs 51, 52, 53 and 54 are pressed into the current collecting terminal 20 and the resin film 40. It is preferable that the jigs 51 to 54 are heated. In the thickness direction D T 10(c), the length of jigs 52 and 54 (the length in the vertical direction in the drawing) is shorter than the length of current collecting terminal 20 (the length in the vertical direction in the drawing). Therefore, for example, a gap is generated between jigs 51 and 52, and the excess portion of resin film 40 gathers in the gap. This forms protrusions P of the resin film as shown in FIG. 10(c). The thickness of protrusions P can be adjusted by the amount of the gap between jigs 51 and 52.

[0035] 2. Battery components The battery according to the present disclosure comprises an electrode body, a current collecting terminal, and a laminate film.

[0036] (1) Electrode body As shown in FIG. 11 , for example, the electrode body in the present disclosure is configured by stacking a positive electrode current collector 1, a positive electrode active material layer 2, an electrolyte layer 3, a negative electrode active material layer 4, and a negative electrode current collector 5 in a thickness direction D T In this order, when the positive electrode active material layer 2, the electrolyte layer 3, and the negative electrode active material layer 4 are regarded as a power generation unit, the electrode body preferably has a plurality of power generation units. As shown in FIG. 11, the positive electrode current collector 1 preferably has a positive electrode tab 1t, and the negative electrode current collector 5 preferably has a negative electrode tab 5t.

[0037] The positive electrode active material layer contains at least a positive electrode active material. The positive electrode active material layer may further contain at least one of a conductive material, an electrolyte, and a binder. Examples of the positive electrode active material include oxide active materials. Examples of the oxide active material include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3Examples of the positive electrode active material include rock salt layer type active materials such as O2, spinel type active materials such as LiMn2O4, and olivine type active materials such as LiFePO4. Sulfur (S) may also be used as the positive electrode active material. The positive electrode active material may be, for example, in the form of particles.

[0038] Examples of the conductive material include carbon materials. The electrolyte may be a solid electrolyte or a liquid electrolyte. The solid electrolyte may be an organic solid electrolyte such as a gel electrolyte, or an inorganic solid electrolyte such as an oxide solid electrolyte or a sulfide solid electrolyte. The liquid electrolyte (electrolytic solution) contains, for example, a supporting salt such as LiPF6 and a solvent such as a carbonate-based solvent. Examples of the binder include a rubber-based binder and a fluoride-based binder.

[0039] The negative electrode active material layer contains at least a negative electrode active material. The negative electrode active material layer may further contain at least one of a conductive material, an electrolyte, and a binder. Examples of the negative electrode active material include metal active materials such as Li and Si, carbon active materials such as graphite, Li4Ti5O 12 The oxide active material may be in the form of, for example, particles or foil. The conductive material, electrolyte and binder are the same as those described above.

[0040] The electrolyte layer is disposed between the positive electrode active material layer and the negative electrode active material layer, and contains at least an electrolyte. The electrolyte may be a solid electrolyte or a liquid electrolyte. The electrolyte is the same as that described above. The electrolyte layer may have a separator.

[0041] The positive electrode current collector collects the current from the positive electrode active material layer. Examples of the material of the positive electrode current collector include metals such as aluminum, SUS, and nickel. Examples of the shape of the positive electrode current collector include a foil shape and a mesh shape. The positive electrode current collector may have a positive electrode tab for connecting to a positive electrode current collector terminal.

[0042] The negative electrode current collector collects the current from the negative electrode active material layer. Examples of the material for the negative electrode current collector include metals such as copper, SUS, and nickel. Examples of the shape of the negative electrode current collector include a foil shape and a mesh shape. The negative electrode current collector may have a negative electrode tab for connecting to a negative electrode current collector terminal.

[0043] (2) Current collector terminal The current collecting terminal in the present disclosure is disposed on the side of the electrode body. The current collecting terminal refers to a terminal having a current collecting portion at least in a portion thereof. The current collecting portion is, for example, electrically connected to a tab in the electrode body. The current collecting terminal may be entirely the current collecting portion, or may be partially the current collecting portion. Examples of materials for the current collecting terminal include metals such as aluminum and SUS.

[0044] (3) Laminate film The laminate film in the present disclosure has at least a structure in which an inner resin layer and a metal layer are laminated. The laminate film may have an inner resin layer, a metal layer, and an outer resin layer in this order along the thickness direction. Examples of the material of the inner resin layer include olefin resins such as polypropylene (PP) and polyethylene (PE). Examples of the material of the metal layer include aluminum, aluminum alloys, and stainless steel. Examples of the material of the outer resin layer include polyethylene terephthalate (PET) and nylon. The thickness of the inner resin 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 100 μm or less. The thickness of the outer 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. A resin film may be disposed between the laminate film and the current collecting terminal. Examples of materials for the resin film include olefin resins such as polypropylene (PP) and polyethylene (PE).

[0045] (4)Battery The battery in the present disclosure is typically 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 in the present disclosure may also be used as a power source for moving objects other than vehicles (e.g., railways, ships, and aircraft), or as a power source for electrical products such as information processing devices. The present disclosure may also provide a battery module in which a plurality of the above-mentioned batteries are stacked in the thickness direction.

[0046] 3. Battery manufacturing method A method for manufacturing a battery in the present disclosure includes, for example, a preparation step of preparing a structure having the electrode body and the collector terminal, a first covering step of covering a surface of the electrode body in the structure that constitutes the outer edge with the laminate film, and a second covering step of covering a surface of the collector terminal in the structure that constitutes the outer edge with the laminate film.

[0047] (1) Preparation process The preparation step is a step of preparing a structure having the electrode body and the current collector terminal. The electrode body and the current collector terminal are the same as those described in "A. Battery" above, so a description thereof will be omitted here.

[0048] (2) First coating process The first covering step in the present disclosure is a step of covering the outer edge of the electrode body in the structure with the laminate film. For example, as shown in Figs. 2(a) and (b), in the first covering step, the surfaces constituting the outer edge of the electrode body 10 (for example, the bottom surface portion 12, the second side surface portion 14, the top surface portion 11, and the fourth side surface portion 16) are covered with the laminate film 30. At this time, the electrode body 10 and the laminate film 30 may or may not be welded. In addition, as shown in Fig. 2(b), the end overlap portion Z where the ends of the laminate film 30 overlap is heated. As a result, an end contact portion Y where the ends of the laminate film 30 are welded together is formed. The laminate film may be previously folded to match the shape of the electrode body.

[0049] (3) Second coating process The second covering step in the present disclosure is a step of covering the surface constituting the outer edge of the collector terminal with the laminate film. In addition, it is preferable to form a welded portion in the second covering step. In addition, the above-mentioned resin film may be disposed on the surface of the collector terminal, and then the surface may be covered with the laminate film.

[0050] In the second covering step, the current collecting terminal and the laminate film are welded together using a jig capable of surface contact with the surface constituting the outer edge of the current collecting terminal. FIG. 12 is a schematic side view illustrating the second covering step in the present disclosure. As shown in FIG. 12(a), a space S is formed between the laminate film 30 and the current collecting terminal 20 by the above-mentioned first covering step. Furthermore, an end contact portion Y is formed by the above-mentioned first covering step. Next, as shown in FIG. 12(b), jigs 61, 62, 63, and 64 are pressed into the laminate film 30 and the current collecting terminal 20. It is preferable that the jigs 61 to 64 are heated. In the thickness direction D, T12(c), the length of the jigs 62 and 64 (the length in the vertical direction in the drawing) is shorter than the length of the current collecting terminal 20 (the length in the vertical direction in the drawing). Therefore, for example, a gap is generated between the jigs 61 and 62, and the excess portion of the laminate film 30 gathers in the gap. As a result, as shown in FIG. 12(c), a welded portion X is formed, and the battery 100 is obtained. The thickness of the first resin layer at the welded portion X can be adjusted by the amount of the gap between the jigs 61 and 62.

[0051] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits similar effects is included in the technical scope of the present disclosure. EXAMPLES

[0052] A laminate film having Al as a metal layer and PE as an inner resin layer was prepared. Next, a structure having an electrode body and a current collector terminal was prepared in the same manner as in FIG. 2, and the surface constituting the outer edge of the electrode body in the structure was covered with a laminate film. Next, in the same manner as in FIG. 12, the surface constituting the outer edge of the current collector terminal was covered with the above-mentioned laminate film to prepare a battery. At this time, the height of the jig 62 and the jig 64 in FIG. 12 were adjusted to obtain a T a / T c The obtained battery was subjected to a thermal shock test (-15°C to 95°C). After every 500 cycles, the metal layer (Al) in the laminate film was observed under a microscope to check for the occurrence of cracks. The results are shown in Table 1.

[0053] [Table 1]

[0054] As shown in Table 1, T a / T c When T was 4.0 or less, no damage was observed in the laminate film even after 5,000 cycles. a / Tc When T is 5.0, no damage is observed in the laminate film up to 4500 cycles, and T a / T c When T is 6.0, no damage is observed in the laminate film up to 2000 cycles, and T a / T c When the strain rate was 7.0, no damage was observed in the laminate film up to 500 cycles.

[0055] The maximum number of cycles in which no damage was found in the laminate film is defined as the number of endurance cycles. a / T c The relationship between the number of cycles and durability is shown in Figure 13. As shown in Figure 13, T a / T c It was confirmed that when the resistance is 4.0 or less, the number of durability cycles is significantly improved. [Explanation of symbols]

[0056] 10...Electrode body 11...Top part 12…Bottom part 13...First side part 14…Second side part 15…Third side part 16…Fourth side part 20...Current collector terminal 30...Laminating film 100...battery

Claims

1. An electrode body; A current collecting terminal disposed on a side surface of the electrode body; A laminate film covering the electrode body; A battery comprising: When the battery is viewed from the side of the current collecting terminal, an outer edge of the current collecting terminal is located inside an outer edge of the electrode body, the laminate film is disposed so as to cover a surface constituting the outer edge of the current collecting terminal and a surface constituting the outer edge of the electrode body; A welded portion in which inner surfaces of the laminate film are welded to each other is disposed at a corner of the current collecting terminal, The laminate film has at least a metal layer, In the welded portion, a first resin layer is disposed between the opposing metal layers, a second resin layer is disposed between the metal layer and the current collecting terminal; The thickness of the first resin layer is T ａ and the thickness of the second resin layer is T ｂ In this case, the T ａ and the T ｂ satisfies T a >T b; When the thickness of the metal layer in the welded portion is Tc, the T a and T c satisfy 0.5≦T a / T c ≦4; When the battery is viewed from the side of the current collector terminal, the shape of the current collector terminal is rectangular, The welded portions are disposed at four corners that form an outer edge of the current collecting terminal.

2. The laminate film has an inner resin layer on a surface of the metal layer facing the current collector terminal, The battery of claim 1 , wherein the first resin layer and the second resin layer each comprise the inner resin layer.

3. a resin film is disposed between the inner resin layer and the current collecting terminal; The battery according to claim 2 , wherein the first resin layer comprises the resin film.

Images