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 a battery.

Background Art

[0002] A battery such as a lithium-ion secondary battery generally includes 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, for example, in an internal space surrounded by an exterior material. 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 for sealing the exterior material, wherein a first electrode terminal and a second electrode terminal are respectively drawn out to the outside through the first cover and the second cover. Further, Patent Document 1 describes a laminate film as the exterior material. Patent Document 2 discloses a battery using an exterior body made of a single film, in which a rib structure is provided by stacking a plurality of the films at a corner of a side orthogonal to an end face where a current collecting tab lead is extended.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] As shown in FIG. 3 described later, the size of the current collector terminal may be smaller than the size of the electrode body. When a current collector terminal having such a dimensional relationship is sealed with a laminate film, for example, wrinkles may occur in the laminate film, and the sealing performance of the battery may deteriorate. In order to solve such problems, the inventors conceived of providing a welded portion on the current collector terminal where the inner surfaces of the laminate films are welded to each other. By providing the welded portion, a decrease in sealing performance can be suppressed. Further, the welded portion is often provided at the corner of the current collector terminal in the manufacturing process. From the viewpoint of suppressing a decrease in sealing performance, it is desirable to suppress the occurrence of poor welding in the welded portion.

[0005] The present disclosure has been made in view of the above circumstances, and the main object thereof is to provide a battery in which the occurrence of poor welding in the welded portion is suppressed.

Means for Solving the Problems

[0006] [1] A battery including an electrode body, a current collector terminal disposed on a side surface portion of the electrode body, and a laminate film covering the electrode body, wherein when the battery is viewed from the side from the current collector terminal side, an outer edge of the current collector 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 collector terminal and a surface constituting the outer edge of the electrode body, a welded portion where inner surfaces of the laminate film are welded to each other is disposed at a corner of the current collector terminal, the laminate film has at least a metal layer, a first resin layer is disposed between the opposing metal layers in the welded portion, a second resin layer is disposed between the metal layer and the current collector terminal, and a thickness of the first resin layer is T a is defined as, and a thickness of the second resin layer is T b in such a case, the T a and the T b satisfy 0.25 ≦ T a / T b A battery that satisfies the above.

[0007] [2] When the thickness of the metal layer in the welded portion is T c in such a case, the Ta and the above T c satisfies 0.5 ≦ T a / T c ≦ 4, the battery according to [1].

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

[0009] [4] A resin film is disposed between the above inner resin layer and the above current collecting terminal, and the above first resin layer includes the above resin film, the battery according to [3]. [Advantages of the Invention]

[0010] The battery in the present disclosure has an effect of suppressing the occurrence of poor welding at the welded portion. [Brief Description of the Drawings]

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments in the present disclosure will be described in detail with reference to the drawings. Each of the drawings shown below is schematically illustrated, and the size and shape of each part are appropriately exaggerated for easy understanding. Also, in this specification, when expressing the mode of arranging one member with respect to another member, when simply described as "above" or "below", unless otherwise specified, it includes both the case where another member is arranged directly above or directly below so as to be in contact with a certain member, and the case where 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 current collecting terminals 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 surface portions (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. Further, in FIG. 1(b), a first current collecting terminal 20A is arranged on the first side surface portion 13 of the electrode body 10, and a second current collecting terminal 20B is arranged 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] FIG. 2 is a schematic perspective view illustrating an electrode body, a current collector terminal, and a laminate film in the present disclosure. As shown in FIG. 2(a), the laminate film 30 is, for example, a single film. Further, as shown in FIGS. 2(a) and 2(b), the laminate film 30 is folded so as to cover the entire 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. On the other hand, in FIG. 2(b), at least a part of the first current collector terminal 20A and at least a part of the second current collector 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 collector terminal in the present disclosure, and FIG. 3(b) is a cross-sectional view taken along line A-A of FIG. 3(a). As shown in FIGS. 3(a) and 3(b), when the electrode body 10 and the current collector terminal 20 are observed from the current collector terminal 20 side, the outer edge E2 of the current collector terminal 20 is located inside the outer edge E1 of the electrode body 10. That is, the dimension of the current collector terminal 20 is smaller than the dimension of the electrode body 10. Further, as shown in FIG. 3(b), the electrode body 10 has a current collecting tab T on the side surface portion SS 10 The current collecting tab T is joined on the surface of the current collector terminal 20 (the surface facing the side surface portion SS of the electrode body 10). 10

[0016] FIG. 3(c) is a schematic side view illustrating an electrode body, a current collector terminal, and a laminate film in the present disclosure, and FIG. 3(d) is a cross-sectional view taken along line A-A of FIG. 3(c). As shown in FIGS. 3(c) and 3(d), when the electrode body 10, the current collector terminal 20, and the laminate film 30 are observed from the current collector terminal 20 side, a space S is formed between the laminate film 30 and the current collector terminal 20. Therefore, when the current collector terminal 20 is sealed with the laminate film 30, wrinkles may occur in the laminate film 30 due to the surplus portion of the laminate film 30, and the sealing performance of the battery may be deteriorated. On the other hand, in the battery in the present disclosure, as shown in FIGS. 4(a) and 4(b), a welded portion X where the inner surfaces (the surfaces on the current collector terminal 20 side) of the laminate film 30 are welded to each other is disposed at the corner of the current collector terminal 20. By providing the welded portion X, it is possible to suppress a decrease in the sealing performance due to wrinkles in the laminate film.

[0017] The laminated film 30 shown in FIG. 5 has a metal layer 31, an inner resin layer 32 disposed on the surface of the metal layer 31 on the side of the current collector terminal 20, and an outer resin layer 33 disposed on the surface of the metal layer 31 opposite to the current collector terminal 20. Further, in the welded portion X, a first resin layer R1 is disposed between the opposing metal layers 31. Also, a second resin layer R2 is disposed 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 laminated film 30. Also, the first resin layer R1 and the second resin layer R2 are disposed continuously. As shown in FIG. 5, let the thickness of the first resin layer R1 be T a and the thickness of the second resin layer R2 be T b . When this is the case, T a and T b satisfy 0.25 ≦ T a / T b .

[0018] According to the present disclosure, since the welded portion is disposed on the current collector terminal, a battery with suppressed deterioration of the sealing property is obtained. As shown in FIG. 3 described above, the dimensions of the current collector 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 collector terminals from coming into contact. By preventing contact between adjacent current collector terminals, the occurrence of battery breakage is less likely to occur. Also, when a current collector terminal having such a dimensional relationship is sealed with a laminated film, for example, wrinkles may occur in the laminated film, and the sealing property of the battery may deteriorate. In the present disclosure, by disposing the welded portion X where the inner surfaces of the laminated film are welded on the current collector terminal, even when the dimensions of the current collector terminal are made smaller than the dimensions of the electrode body, a battery with suppressed deterioration of the sealing property is obtained. On the other hand, as described above, the welded portion is often provided at the corner of the current collector terminal in the manufacturing process. From the viewpoint of suppressing deterioration of the sealing property, it is desirable to suppress the occurrence of poor welding in the welded portion. In contrast, according to the present disclosure, by making T a larger than T b , the adhesion in the welded portion is improved, and the occurrence of poor welding in the welded portion can be suppressed.

[0019] 1. Configuration of the battery The battery in 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 generation element of the battery. The shape of the electrode body is not particularly limited. For example, as shown in FIG. 1(a), it has a top surface portion 11, a bottom surface portion 12 facing the top surface portion 11, and four side surface portions (the first side surface portion 13, the second side surface portion 14, the third side surface portion 15, and the fourth side surface portion 16) connecting the top surface portion 11 and the bottom surface portion 12. Both the top surface portion 11 and the bottom surface portion 12 correspond to the main surfaces of the electrode body, and the normal direction of the main surface can be defined as the thickness direction. Also, 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. For example, quadrilaterals such as a square, a rectangle, a rhombus, a trapezoid, and a parallelogram can be mentioned. The shape of the top surface portion 11 in FIG. 1(a) is a rectangle. Also, the shape of the top surface portion may be a polygon other than a quadrilateral, or a shape having a curve such as a circle. Also, 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. For example, quadrilaterals such as a square, a rectangle, a rhombus, a trapezoid, and a parallelogram can be mentioned.

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

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

[0024] When the battery is viewed from the side on the current collector terminal side, the outer edge of the current collector 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 collector terminal 20 is located inside the outer edge E1 of the electrode body 10. In other words, the outer edge E2 of the current collector terminal 20 is entirely surrounded by the outer edge E1 of the electrode body 10.

[0025] For example, in Fig. 3(a), let the length (total peripheral length) of the outer edge E1 of the electrode body 10 be L1, and the length (total peripheral length) of the outer edge E2 of the current collector terminal 20 be L2. The ratio (L2 / L1) of L2 to L1 is, for example, 0.7 or more and less than 1, and may be 0.8 or more and 0.95 or less. Also, for example, in Fig. 3(a), let the length of the outer edge E1 in the thickness direction D T be L a and the length of the outer edge E2 in the thickness direction D T be L b . The ratio (L a / L b ) of L b to L a is, for example, 0.5 or more and less than 1, and may be 0.8 or more and 0.95 or less. Also, for example, in Fig. 3(a), let the length of the outer edge E1 in the direction perpendicular to the thickness direction D T be L c and the length of the outer edge E2 in the direction perpendicular to the thickness direction D T be L d . The ratio (L c / L d ) of L d to L c(3) is, for example, 0.5 or more and less than 1, and may be 0.8 or more and 0.95 or less. Further, for example, in FIG. 3(a), let the length of the gap between the outer edge E1 and the outer edge E2 be δ. δ may be greater than 0 mm and may be 0.3 mm or more, and may be 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 collector terminal. As shown in FIG. 2, when observing the electrode body 10 and the current collector terminal 20 from the side of the current collector terminal 20, the laminate film 30 is arranged to cover the surface constituting the outer edge of the current collector terminal 20 and the surface constituting the outer edge of the electrode body 10. Further, as shown in FIG. 4(a), at the corner of the current collector terminal 20, a welded portion X where the inner surfaces of the laminate film 30 are welded together is arranged. It is preferable that the welded surface in the welded portion X has no voids. The laminate film may have one welded portion X or two or more welded portions X. Also, welded portions X may be respectively arranged at two corners of the current collector terminal facing each other in the thickness direction. Further, in FIG. 4(a), an end contact portion Y where the ends of the laminate film 30 are welded together is arranged. The end contact portion Y may be bent according to the shape of the current collector terminal. This is because surplus space can be reduced. Further, as shown in FIG. 4(b), the shape of the current collector terminal 20 is a quadrilateral, and welded portions X may be respectively arranged at all its corners. In FIG. 4(b), the end contact portion Y is arranged on the side connecting two corners.

[0027] As shown in FIG. 6, the welded portion X may have a first surface S a and a second surface S b and a curved surface S a connecting the first surface S b and the second surface S c . The second surface S b is opposed to the first surface S a and is located outside the first surface S T in the thickness direction D a of the battery. Also, the first surface Sa The normal direction of and the second surface S b The normal direction of is preferably parallel to the thickness direction D of the battery. "Parallel" means that the angle formed by the two is 20° or less. T In FIG. 6, when the battery is viewed from the side in the direction of the current collecting terminal 20, the welding portion X is disposed at the corner t that constitutes the outer edge E2 of the current collecting terminal 20. Further, as shown in FIG. 6, let the width of the welding portion X be w1. The width w1 is, for example, 0.1 mm or more, may be 0.3 mm or more, and 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.

[0028] In FIG. 6, when the battery is viewed from the side in the direction of the current collecting terminal 20, the welding portion X is disposed at the corner t that constitutes the outer edge E2 of the current collecting terminal 20. Further, as shown in FIG. 6, let the width of the welding portion X be w1. The width w1 is, for example, 0.1 mm or more, may be 0.3 mm or more, and 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, let the end position of the laminate film 30 on the current collecting terminal 20 side be α, and let the position of the laminate film 30 corresponding to the boundary between the current collecting terminal 20 and the electrode body 10 be β. The welding portions X in FIGS. 7 and 8 are continuously arranged from the end position α to the position β. Further, when the direction (axial direction) in which the current collecting terminal 20 extends from the electrode body 30 is D1, the welding portion X is preferably arranged along D1. Further, the welding portion X may be arranged in at least a part of the region from the end position α to the position β in D1. The length of the welding portion X in D1 is, for example, 1 mm or more, may be 3 mm or more, and 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 on the current collecting terminal 20 side. Further, the laminate film 30 preferably has an outer resin layer 33 on the surface of the metal layer 31 opposite to the current collecting terminal 20. In the welding portion X, a first resin layer R1 is disposed between the opposing metal layers 31. Further, a second resin layer R2 is disposed between the metal layer 31 and the current collecting terminal 20. As shown in FIG. 5, let the thickness of the first resin layer R1 be T a and let the thickness of the second resin layer R2 be T b and. T aand T b satisfies 0.25 ≦ T a / T b . T a / T b may be 0.5 or more, 0.75 or more, 1.0 or more, 1.1 or more, 1.2 or more. On the other hand, T a / T b is, for example, less than 2.0, and may be 1.8 or less. T a and T b are preferably the average values of the thicknesses measured at a plurality of locations, respectively. Also, the values of T a and T b can be controlled by appropriately adjusting the conditions for coating the current collector terminal with the laminate film.

[0031] As shown in FIG. 5, let the thickness of the metal layer 31 in the welded portion X be T c . T a and T c preferably satisfy 0.5 ≦ T a / T c ≦ 7. This is because breakage of the welded portion X due to thermal shock can be suppressed. When a thermal shock is applied to the battery, the first resin layer in the welded portion X expands more than the metal layer. Therefore, if T a / T c is too large, the metal layer may be damaged due to the stress during expansion. In contrast, by setting T a / T c to 7 or less, breakage of the welded portion X due to thermal shock can be suppressed. Also, if T a / T c is too small, good sealing performance may not be obtained. T a / T c may be 0.75 or more, 1.0 or more. On the other hand, T a / T c may be 4.0 or less, 3.5 or less. When T a / T c is 4.0 or less, breakage of the welded portion X due to thermal shock is significantly suppressed. T cis preferably the average value of the thicknesses measured at a plurality of locations. Also, T c The value of is basically not affected by the conditions for coating the current collector terminal with the laminate film.

[0032] As shown in FIG. 9(a), a resin film 40 may be disposed between the inner resin layer 32 in the laminate film 30 and the current collector terminal 20. By disposing the resin film 40, the adhesion between the laminate film 30 and the current collector 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 the 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 voids from occurring 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 located outside the third surface in the thickness direction D of the battery T In, it is located outside the third surface. Also, the normal direction of the third surface and the normal direction of the fourth surface are preferably parallel to the thickness direction D of the battery T Let the width of the welded portion X be w1 and the width of the protrusion of the resin film 40 be w2 as shown in FIG. 9(b). The ratio (w2 / w1) of the width w2 to the width w1 may be, for example, 0.1 or more, may be 0.3 or more, and 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, and 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 of forming protrusions on a resin film in the present disclosure. As shown in FIG. 10(a), a resin film 40 is disposed around a current collector 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 collector terminal 20. Next, as shown in FIG. 10(b), jigs 51, 52, 53, and 54 are pushed into the current collector terminal 20 and the resin film 40. The jigs 51 to 54 are preferably heated. In the thickness direction D T the lengths of the jigs 52 and 54 (the lengths in the vertical direction of the drawing) are shorter than the length of the current collector terminal 20 (the length in the vertical direction of the drawing). Therefore, for example, a gap is formed between the jigs 51 and 52, and an excess portion of the resin film 40 gathers in the gap. As a result, as shown in FIG. 10(c), protrusions P of the resin film are formed. The thickness of the protrusions P can be adjusted by the amount of the gap between the jigs 51 and 52.

[0035] 2. Battery members The battery in the present disclosure includes an electrode body, a current collector terminal, and a laminate film.

[0036] (1) Electrode body The electrode body in the present disclosure has, for example, as shown in FIG. 11, 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 this order in the thickness direction D T When the positive electrode active material layer 2, the electrolyte layer 3, and the negative electrode active material layer 4 are used as a power generation unit, the electrode body preferably has a plurality of power generation units. Further, 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 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. Also, sulfur (S) may be used as the positive electrode active material. The shape of the positive electrode active material is, for example, particulate.

[0038] Examples of the conductive material include, for example, 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. Also, the liquid electrolyte (electrolyte solution) contains, for example, a supporting salt such as LiPF6 and a solvent such as a carbonate-based solvent. Examples of the binder include, for example, 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, for example, metal active materials such as Li and Si, carbon active materials such as graphite, and oxide active materials such as Li4Ti5O 12 etc. The shape of the negative electrode active material is, for example, particulate or foil-like. The conductive material, electrolyte, and binder are the same as 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 described above. The electrolyte layer may have a separator.

[0041] The positive electrode current collector conducts current collection for 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, for example, foil-like and mesh-like. The positive electrode current collector may have a positive electrode tab for connection to a positive electrode current collection terminal.

[0042] The negative electrode current collector conducts the current collection of the negative electrode active material layer. Examples of the material of 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 the negative electrode current collection terminal.

[0043] (2) Current collection terminal In the present disclosure, the current collection terminal is disposed on the side surface portion of the electrode body. The current collection terminal refers to a terminal having a current collection portion at least partially. The current collection portion is electrically connected to, for example, a tab in the electrode body. The entire current collection terminal may be the current collection portion, or a part thereof may be the current collection portion. Examples of the material of the current collection 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. Further, 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 alloy, 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. Further, a resin film may be disposed between the laminate film and the current collection terminal. Examples of the material of 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 the applications of the battery include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), gasoline vehicles, and diesel vehicles. In particular, it is preferably used as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or battery electric vehicles (BEVs). Further, the battery in the present disclosure may be used as a power source for moving bodies other than vehicles (e.g., railways, ships, airplanes), and may also be used as a power source for electrical products such as information processing devices. In the present disclosure, it is also possible to provide a battery module in which a plurality of the above-described batteries are stacked in the thickness direction.

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

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

[0048] (2) First covering step The first covering step in the present disclosure is a step of covering the outer edge of the electrode body in the above structure with the above laminate film. For example, as shown in FIGS. 2(a) and 2(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. Further, as shown in FIG. 2(b), the end overlapping portion Z where the ends of the laminate film 30 overlap each other is heated. Thereby, an end contact portion Y where the ends of the laminate film 30 are welded is formed. The laminate film may be pre-bent according to the shape of the electrode body.

[0049] (3) Second covering step The second covering step in the present disclosure is a step of covering the surface constituting the outer edge of the current collector terminal with the above laminate film. Further, in the second covering step, it is preferable to form a welded portion. Further, after disposing the above-described resin film on the surface of the current collector terminal, it may be covered with a laminate film.

[0050] In the second covering step, the current collector terminal and the laminate film are welded using a jig capable of surface contact with the surface constituting the outer edge of the current collector 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 collector terminal 20 by the above-described first covering step. Further, an end contact portion Y is formed by the above-described first covering step. Next, as shown in FIG. 12(b), jigs 61, 62, 63, and 64 are pushed into the laminate film 30 and the current collector terminal 20. The jigs 61 to 64 are preferably heated. Thickness direction D TIn this case, the lengths of the jigs 62 and 64 (the lengths in the vertical direction of the drawing) are shorter than the length of the current collecting terminal 20 (the length in the vertical direction of the drawing). Therefore, for example, a gap is formed between the jigs 61 and 62, and the surplus portion of the laminate film 30 gathers in this gap. As a result, as shown in FIG. 12(c), the welded portion X is formed, and the battery 100 is obtained. The thickness of the first resin layer in the welded portion X can be adjusted according to 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 examples, and any configuration that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits the same operational effects is included in the technical scope of the present disclosure.

Example

[0052] A laminate film having Al as a metal layer and PE as an inner resin layer was prepared. Next, in the same manner as in FIG. 2, a structure having an electrode body and a current collecting terminal was prepared, and the surface constituting the outer edge of the electrode body in the structure was covered with the laminate film. Next, in the same manner as in FIG. 12, the surface constituting the outer edge of the current collecting terminal was covered with the above laminate film to fabricate a battery. At this time, by adjusting the heights of the jigs 62 and 64 in FIG. 12, T a / T c was adjusted. A thermal shock test (-15°C to 95°C) was performed on the obtained battery. Every 500 cycles, the metal layer (Al) in the laminate film was observed with a microscope to confirm the presence or absence of cracks. The results are shown in Table 1.

[0053]

Table 1

[0054] As shown in Table 1, when T a / T c is 4.0 or less, no damage was confirmed in the laminate film even after 5000 cycles. On the other hand, T a / Tc When it is 5.0, no damage is confirmed in the laminate film up to 4500 cycles, and T a / T c When it is 6.0, no damage is confirmed in the laminate film up to 2000 cycles, and T a / T c When it is 7.0, no damage was confirmed in the laminate film up to 500 cycles.

[0055] Also, the maximum number of cycles in which no damage is confirmed in the laminate film is defined as the number of endurance cycles. T a / T c The relationship with the number of endurance cycles is shown in FIG. 13. As shown in FIG. 13, T a / T c When it is 4.0 or less, it was confirmed that the number of endurance cycles was significantly improved.

Explanation of Signs

[0056] 10…Electrode body 11…Top surface part 12…Bottom surface part 13…First side surface part 14…Second side surface part 15…Third side surface part 16…Fourth side surface part 20…Current collecting terminal 30…Laminate 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 laminate film has an inner resin layer on a surface of the metal layer facing the current collector terminal, a resin film is disposed between the inner resin layer and the current collecting terminal; the first resin layer includes the inner resin layer and the resin film, the second resin layer includes the inner resin layer, the resin film includes a protrusion located at the corner of the current collecting terminal, The welded portion is formed so as to cover the protrusion.

2. 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 0.25≦T ａ / T ｂ The battery of claim 1 .

3. 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 , T ａ >T ｂ Fulfilling The thickness of the metal layer at the welded portion is T ｃ In this case, the T ａ and the T ｃ 0.5≦T ａ / T ｃ ≦4 is satisfied, When the battery is viewed from the side of the current collector terminal, the shape of the current collector terminal is rectangular, The battery according to claim 1 , wherein the welded portions are disposed at four corners constituting an outer edge of the current collector terminal.

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