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] This disclosure relates to batteries. [Background technology]

[0002] Batteries such as lithium-ion secondary batteries typically comprise 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 outer casing material, for example. Patent Document 1 discloses a lithium polymer secondary battery comprising an electrode assembly, an outer casing material surrounding the outside of the electrode assembly, and first and second covers sealing the outer casing material, with first electrode terminals and second electrode terminals being led out to the outside via the first and second covers, respectively. Patent Document 1 also describes laminate film as the outer casing material. Patent Document 2 discloses a battery using an outer casing made of a single film, wherein a rib structure is provided at the corner of the edge perpendicular to the end face on which the current collecting tab lead extends, by stacking multiple films. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2011-108623 [Patent Document 2] Japanese Patent Publication No. 2021-190281 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] As shown in Figure 3, described later, the dimensions of the current collector terminal are sometimes made smaller than the dimensions of the electrode body. When current collector terminals with such dimensional relationships are sealed with laminate film, wrinkles may form in the laminate film, for example, which can reduce the sealing performance of the battery. To solve this problem, the inventors conceived of providing a welded section on the current collector terminal where the inner surfaces of the laminate film are welded together. By providing a welded section, the reduction in sealing performance can be suppressed. In addition, due to the manufacturing process, the welded section is often provided at the corner of the current collector terminal. From the viewpoint of suppressing the reduction in sealing performance, it is desirable to suppress the occurrence of welding defects at the welded section.

[0005] This disclosure has been made in view of the above circumstances, and its main purpose is to provide a battery that suppresses the occurrence of welding defects in the welded portion. [Means for solving the problem]

[0006] [1] A battery comprising an electrode body, a current collector terminal disposed on the side 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, the outer edge of the current collector terminal is located inward from the outer edge of the electrode body, the laminate film is arranged to cover the surface constituting the outer edge of the current collector terminal and the surface constituting the outer edge of the electrode body, a welded portion is provided at the corner of the current collector terminal where the inner surfaces of the laminate film are welded together, the laminate film has at least a metal layer, a first resin layer is provided between the opposing metal layers in the welded portion, a second resin layer is provided between the metal layer and the current collector terminal, and the thickness of the first resin layer is T a The thickness of the second resin layer is set to T. b In that case, the above T a and the above T b is 0.25≦T a / T b A battery that satisfies the requirements.

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

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

[0009] [4] A resin film is disposed between the inner resin layer and the current collector terminal, and the first resin layer includes the 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 in the welded portion. [Brief Description of the Drawings]

[0011] [Figure 1] It is a schematic perspective view illustrating an electrode body and a current collector terminal in the present disclosure. [Figure 2] [[ID=三十七]]It is a schematic perspective view illustrating an electrode body, a current collector terminal, and a laminate film in the present disclosure. [[ID=3 ninety]] [Figure 3] It is a schematic side view and a schematic cross-sectional view illustrating an electrode body, a current collector terminal, and a laminate film in the present disclosure. [Figure 4] It is a schematic side view illustrating a part of the battery in the present disclosure. [Figure 5] It is a schematic side view illustrating a part of the battery in the present disclosure. [Figure 6] It is a schematic side view illustrating a part of the battery in the present disclosure. [Figure 7] It is a schematic plan view illustrating a part of the battery in the present disclosure. [Figure 8] It is a schematic perspective view illustrating a part of the battery in the present disclosure. [Figure 9] This is a schematic side view illustrating a part of the battery described in this disclosure. [Figure 10] This is a schematic side view illustrating a method for forming protrusions on a resin film according to this disclosure. [Figure 11] This is a schematic cross-sectional view illustrating an example of an electrode body in this disclosure. [Figure 12] This is a schematic side view illustrating the second coating step in this disclosure. [Figure 13] These are the results of the thermal shock test on the battery obtained in the example. [Modes for carrying out the invention]

[0012] Embodiments in this disclosure will be described in detail below with reference to the drawings. The following figures are schematic representations, and the size and shape of each part are exaggerated as appropriate for ease of understanding. In addition, in this specification, when describing a manner in which one member is positioned relative to another member, the terms "above" or "below" include, unless otherwise specified, both cases in which one member is positioned directly above or below another member so as to be in contact with that member, and cases in which one member is positioned above or below another member via another member.

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

[0014] Figure 2 is a schematic perspective view illustrating the electrode body, current collector terminals, and laminate film in this disclosure. As shown in Figure 2(a), the laminate film 30 is, for example, a single film. Also, as shown in Figures 2(a) and (b), the laminate film 30 is folded to cover the entire bottom surface 12, second side surface 14, top surface 11, and fourth side surface 16 of the electrode body 10. On the other hand, in Figure 2(b), at least a portion of the first current collector terminal 20A and at least a portion of the second current collector terminal 20B are located inside the folded laminate film 30.

[0015] Figure 3(a) is a schematic side view illustrating the electrode body and current collector terminal in this disclosure, and Figure 3(b) is a cross-sectional view AA of Figure 3(a). As shown in Figures 3(a) and (b), when the electrode body 10 and 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 inward from the outer edge E1 of the electrode body 10. That is, the dimensions of the current collector terminal 20 are smaller than the dimensions of the electrode body 10. Also, as shown in Figure 3(b), the electrode body 10 has a side portion SS 10 It has a current collection tab T. The current collection tab T is on the surface of the current collection terminal 20 (side portion SS of the electrode body 10). 10 They are joined at the opposite surfaces.

[0016] Figure 3(c) is a schematic side view illustrating the electrode body, current collector terminal, and laminate film in this disclosure, and Figure 3(d) is a cross-sectional view AA of Figure 3(c). As shown in Figures 3(c) and (d), when the electrode body 10, current collector terminal 20, and laminate film 30 are observed from the current collector terminal 20 side, a space S is created 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 form in the laminate film 30 due to the excess portion of the laminate film 30, which may reduce the sealing performance of the battery. In contrast, as shown in Figures 4(a) and (b), the battery in this disclosure has a welded portion X at the corner of the current collector terminal 20, where the inner surfaces (the surfaces on the current collector terminal 20 side) of the laminate film 30 are welded together. By providing the welded portion X, the reduction in sealing performance due to wrinkles in the laminate film can be suppressed.

[0017] The laminate film 30 shown in Figure 5 has a metal layer 31, an inner resin layer 32 positioned on the side of the metal layer 31 facing the current collection terminal 20, and an outer resin layer 33 positioned on the side of the metal layer 31 opposite to the current collection terminal 20. In addition, a first resin layer R1 is positioned between the opposing metal layers 31 in the welded portion X. A second resin layer R2 is positioned between the metal layer 31 and the current collection terminal 20. In Figure 5, the first resin layer R1 and the second resin layer R2 are the inner resin layers 32 of the laminate film 30, respectively. Furthermore, the first resin layer R1 and the second resin layer R2 are arranged continuously. As shown in Figure 5, the thickness of the first resin layer R1 is T a The thickness of the second resin layer R2 is set to T b In that case, T a and T b is 0.25≦T a / T b It satisfies the condition.

[0018] According to this disclosure, since the welded portion is positioned on the current collector terminal, the battery has suppressed a decrease in sealing performance. As shown in Figure 3 above, the dimensions of the current collector terminal may be smaller than the dimensions of the electrode body. By adopting such a dimensional relationship, it is possible to prevent adjacent current collector terminals from coming into contact when, for example, multiple batteries are stacked. By preventing contact between adjacent current collector terminals, battery damage is less likely to occur. Furthermore, if current collector terminals with such a dimensional relationship are sealed with a laminate film, wrinkles may form in the laminate film, for example, reducing the sealing performance of the battery. In this disclosure, by positioning a welded portion X, where the inner surfaces of the laminate film are welded together, on the current collector terminal, the battery has suppressed a decrease in sealing performance even when the dimensions of the current collector terminal are smaller than the dimensions of the electrode body. On the other hand, as mentioned above, due to the manufacturing process, the welded portion is often provided at the corner of the current collector terminal. From the viewpoint of suppressing a decrease in sealing performance, it is desirable to suppress the occurrence of welding defects in the welded portion. In response to this, according to this disclosure, T a to T b By making it larger, the adhesion at the welded area is improved, and the occurrence of welding defects at the welded area can be suppressed.

[0019] 1. Battery configuration The battery in this disclosure comprises at least an electrode body, a current collector terminal, and a laminate film.

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

[0021] The shape of the top surface is not particularly limited, but examples include quadrilaterals such as squares, rectangles, rhombuses, trapezoids, and parallelograms. In Figure 1(a), the shape of the top surface 11 is a rectangle. The shape of the top surface may also be a polygon other than a quadrilateral, or a curved shape such as a circle. The shape of the bottom surface is the same as the shape of the top surface. The shape of the side surfaces is not particularly limited, but examples include quadrilaterals such as squares, rectangles, rhombuses, trapezoids, and parallelograms.

[0022] (2) Current collector terminal In this disclosure, the current collector terminals are arranged on the side surface of the electrode body. In this disclosure, it is preferable that the battery has two current collector terminals for one electrode body. For example, as shown in Figure 1(b), a pair of current collector terminals 20 (first current collector terminal 20A and second current collector terminal 20B) may be arranged facing each other with respect to the electrode body 10. Also in Figure 1(b), the pair of current collector terminals 20 are arranged facing each other in the longitudinal direction of the electrode body 10.

[0023] When viewing the battery from the side of the current collection terminal, the shape of the current collection terminal is not particularly limited, but examples include quadrilaterals such as squares, rectangles, rhombuses, trapezoids, and parallelograms. The shape of the current collection terminal 20 in Figure 3(a) is rectangular. In this rectangle, the thickness direction D T The shorter side extends along a direction parallel to the thickness direction D T The longer side extends along a direction perpendicular to it.

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

[0025] For example, in Figure 3(a), let L1 be the length (total circumference) of the outer edge E1 of the electrode body 10, and L2 be the length (total circumference) of the outer edge E2 of the current collection terminal 20. The ratio of L2 to L1 (L2 / 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 Figure 3(a), the thickness direction D T The length of the outer edge E1 in this case is L a Let D be the thickness direction. T The length of the outer edge E2 in this case is L b Let's assume that L a L b The ratio (L b / L a For example, the value of ) may be 0.5 or more and less than 1, and may also be 0.8 or more and 0.95 or less. Also, for example in Figure 3(a), the thickness direction D T The length of the outer edge E1 in the direction perpendicular to it is L. c Let D be the thickness direction. T The length of the outer edge E2 in the direction perpendicular to it is L. d Let's assume that L c L d The ratio (L d / L cFor example, δ may be 0.5 or greater and less than 1, or 0.8 or greater and 0.95 or less. Also, for example in Figure 3(a), let δ be the length of the gap between outer edge E1 and outer edge E2. δ may be greater than 0 mm, 0.3 mm or greater, or 0.5 mm or greater. On the other hand, δ may be 1.5 mm or less.

[0026] (3) Laminating film The laminate film in this disclosure covers the electrode body and seals the electrode body together with the current collector terminal. As shown in Figure 2, when the electrode body 10 and the current collector terminal 20 are observed from the current collector terminal 20 side, the laminate film 30 is positioned 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. Also, as shown in Figure 4(a), a welded portion X is positioned at the corner of the current collector terminal 20, where the inner surfaces of the laminate film 30 are welded together. It is preferable that the welded surface in the welded portion X does not have a gap. The laminate film may have one welded portion X or two or more. Also, welded portions X may be positioned at two opposing corners of the current collector terminal in the thickness direction. Furthermore, in Figure 4(a), an end-adhesion portion Y is positioned where the ends of the laminate film 30 are welded together. The end-adhesion portion Y may be folded to match the shape of the current collector terminal. This is because it reduces the amount of excess space. Also, as shown in Figure 4(b), the shape of the current collection terminal 20 may be rectangular, and welding portions X may be placed at each of its corners. In Figure 4(b), the end contact portion Y is located on the side connecting two corners.

[0027] As shown in Figure 6, the welded portion X is on the first surface S a And, the second face S b And, 1st face S a and the second surface S b Surface S connecting the two surfaces c It may have the following: 2nd surface S b This is the first face S a Opposite to, and in the thickness direction D of the battery T In the first plane S a It is located further out. Also, the first face Sa The normal direction of and the second surface S b The normal direction is the thickness direction D of the battery. T It is preferable that they be parallel. "Parallel" means that the angle between them is 20° or less.

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

[0029] As shown in Figures 7 and 8, when the battery is viewed from above in the thickness direction, the end position of the laminate film 30 on the current collection terminal 20 side is denoted as α, and the position of the laminate film 30 corresponding to the boundary between the current collection terminal 20 and the electrode body 10 is denoted as β. In Figures 7 and 8, the welded portion X is arranged continuously from end position α to position β. Furthermore, if the direction in which the current collection terminal 20 extends from the electrode body 30 (axial direction) is denoted as D1, it is preferable that the welded portion X is arranged along D1. In addition, the welded portion X may be arranged in at least a portion of the area from end position α to 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 Figure 5, the laminate film 30 has at least a metal layer 31. Preferably, the laminate film 30 has an inner resin layer 32 on the side of the metal layer 31 facing the current collection terminal 20. Preferably, the laminate film 30 has an outer resin layer 33 on the side of the metal layer 31 opposite to the current collection terminal 20. In the welded portion X, a first resin layer R1 is placed between the opposing metal layers 31. Also, a second resin layer R2 is placed between the metal layer 31 and the current collection terminal 20. As shown in Figure 5, the thickness of the first resin layer R1 is T a The thickness of the second resin layer R2 is set to T b Let's assume that. aand T b is 0.25≦T a / T b Satisfy T a / T b It may be 0.5 or more, 0.75 or more, 1.0 or more, 1.1 or more, or 1.2 or more. On the other hand, T a / T b For example, it may be less than 2.0 and may be 1.8 or less. a and T b Preferably, each of these values ​​is the average value of the thickness measured at multiple locations. Also, T a and T b The value can be controlled by appropriately adjusting the conditions for covering the current collection terminals with laminate film.

[0031] As shown in Figure 5, the thickness of the metal layer 31 in the welded portion X is T c Let's assume that. a and T c is 0.5≦T a / T c It is preferable that ≤7 be satisfied. This is because damage to the welded portion X due to thermal shock can be suppressed. When thermal shock is applied to the battery, the first resin layer in the welded portion X expands more than the metal layer, so T a / T c If the force is too large, the metal layer may break due to the stress during expansion. In contrast, T a / T c By setting it to 7 or less, damage to the welded part X due to thermal shock can be suppressed. Also, T a / T c If it is too small, a good seal may not be achieved. a / T c It may be 0.75 or higher, or 1.0 or higher. On the other hand, T a / T c It may be 4.0 or less, or 3.5 or less. a / T c If the value is 4.0 or less, damage to the welded joint X due to thermal shock is significantly suppressed. cIt is preferable that this is the average value of the thickness measured at multiple locations. Also, T c The value is basically unaffected by the condition that the current collection terminals are covered with laminate film.

[0032] As shown in Figure 9(a), a resin film 40 may be placed between the inner resin layer 32 of the laminate film 30 and the current collector terminal 20. By placing the resin film 40, the adhesion between the laminate film 30 and the current collector terminal 20 is improved. In Figure 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 Figure 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 protrusions of the resin film 40. By forming the welded portion X so as to cover the protrusions of the resin film 40, it is possible to prevent gaps from forming 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 in the thickness direction D of the battery. T In this configuration, it is located outside the third surface. Furthermore, 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 It is preferable that it be parallel to the surface. Also, as shown in Figure 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 width w2 to 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 value for width w1 is as described above. On the other hand, 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, 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), a protrusion P of the resin film is formed. The thickness of the protrusion 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 of active materials include rock salt layered types 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 shape of the positive electrode active material is, for example, particulate.

[0038] Examples of conductive materials 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 (electrolyte solution) may contain, for example, a supporting salt such as LiPF6 and a solvent such as a carbonate-based solvent. Examples of binders include rubber-based binders and fluoride-based binders.

[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 negative electrode active materials include metallic active materials such as Li and Si, carbon active materials such as graphite, and Li4Ti5O 12 Examples of oxide active materials include the following. 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 positioned 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 as described above. The electrolyte layer may have a separator.

[0041] The positive electrode current collector collects current from the positive electrode active material layer. Examples of materials for the positive electrode current collector include metals such as aluminum, stainless steel, and nickel. Examples of shapes for the positive electrode current collector include foil-like and mesh-like forms. The positive electrode current collector may have a positive electrode tab for connecting to the positive electrode current collection terminal.

[0042] The negative electrode current collector collects current from the negative electrode active material layer. Examples of materials for the negative electrode current collector include metals such as copper, stainless steel (SUS), and nickel. Examples of shapes for the negative electrode current collector include foil-like and mesh-like forms. The negative electrode current collector may have a negative electrode tab for connection to the negative electrode current collection terminal.

[0043] (2) Current collector terminal The current collector terminal in this disclosure is located on the side surface of the electrode body. A current collector terminal is a terminal having a current collector portion in at least part of it. The current collector portion is electrically connected, for example, to a tab in the electrode body. The current collector terminal may be entirely a current collector portion, or only partially a current collector portion. Examples of materials for the current collector terminal include metals such as aluminum and stainless steel.

[0044] (3) Laminating film The laminate film in this disclosure has at least a structure in which an inner resin layer and a metal layer are laminated. The laminate film may also have the inner resin layer, metal layer and outer resin layer in this order along the thickness direction. Examples of materials for the inner resin layer include olefin resins such as polypropylene (PP) and polyethylene (PE). Examples of materials for the metal layer include aluminum, aluminum alloy, and stainless steel. Examples of materials for the outer resin layer include polyethylene terephthalate (PET) and nylon. The thickness of the inner resin layer is, for example, 40 μm to 100 μm. The thickness of the metal layer is, for example, 30 μm to 100 μm. The thickness of the outer resin layer is, for example, 20 μm to 60 μm. The thickness of the laminate film is, for example, 80 μm to 250 μm. A resin film may also be placed between the laminate film and the current collector terminal. Examples of materials for resin films include olefin resins such as polypropylene (PP) and polyethylene (PE).

[0045] (4)Battery The battery in this disclosure is typically a lithium-ion secondary battery. Applications of the battery include, for example, powering vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), gasoline cars, and diesel cars. It is particularly preferable for the battery to be used as a power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). Furthermore, the battery in this disclosure may be used as a power source for mobile devices other than vehicles (e.g., railways, ships, aircraft), or as a power source for electrical products such as information processing devices. In addition, this disclosure may provide a battery module in which multiple of the above-mentioned batteries are stacked in the thickness direction.

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

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

[0048] (2) First coating process The first coating step in this 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 Figures 2(a) and (b), in the first coating step, the surfaces constituting the outer edge of the electrode body 10 (for example, the bottom surface 12, the second side surface 14, the top surface 11, and the fourth side surface 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 together. Also, as shown in Figure 2(b), the overlapping end portion Z where the ends of the laminate film 30 overlap is heated. This forms an end-adhesion portion Y where the ends of the laminate film 30 are welded together. The laminate film may be pre-folded to match the shape of the electrode body.

[0049] (3) Second coating process The second coating step in this disclosure is a step of covering the surface constituting the outer edge of the current collector terminal with the laminate film. It is also preferable to form a welded portion in the second coating step. Alternatively, the resin film described above may be placed on the surface of the current collector terminal and then covered with the laminate film.

[0050] In the second coating step, the current collector terminal and the laminate film are welded together using a jig that can make surface contact with the surface constituting the outer edge of the current collector terminal. Figure 12 is a schematic side view illustrating the second coating step in this disclosure. As shown in Figure 12(a), the first coating step described above creates a space S between the laminate film 30 and the current collector terminal 20. The first coating step also creates an end-adhesion portion Y. Next, as shown in Figure 12(b), jigs 61, 62, 63, and 64 are pressed against the laminate film 30 and the current collector terminal 20. It is preferable that jigs 61-64 are 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 collector terminal 20 (the length in the vertical direction of the drawing). Therefore, for example, a gap is generated 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 structure 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 the metal layer and PE as the inner resin layer was prepared. Next, in the same manner as in FIG. 2, a structure having an electrode body and a current collector terminal was prepared, and the surface constituting the outer edge of the electrode body in the structure was coated with the laminate film. Next, in the same manner as in FIG. 12, the surface constituting the outer edge of the current collector terminal was coated 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 If the value is 5.0, no damage to the laminate film is observed up to 4500 cycles. a / T c If the value is 6.0, no damage to the laminate film is observed up to 2000 cycles. a / T c When the value was 7.0, no damage was observed in the laminating film up to 500 cycles.

[0055] Furthermore, the maximum number of cycles in which no damage was observed in the laminate film is defined as the durability cycle count. a / T c The relationship with the number of endurance cycles is shown in Figure 13. As shown in Figure 13, T a / T c It was confirmed that the number of durability cycles significantly improves when the value is 4.0 or less. [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. Electrode body and A current collection terminal is arranged on the side surface of the electrode body, A laminate film covering the electrode body, A battery equipped with, When the battery is viewed from the side from the current collection terminal side, the outer edge of the current collection terminal is located inward from the outer edge of the electrode body. The laminate film is arranged to cover the surface constituting the outer edge of the current collector terminal and the surface constituting the outer edge of the electrode body. A welded portion, formed by folding the laminate film, is positioned at the corner of the current collection terminal. The laminate film has at least a metal layer, In the welded portion, a first resin layer is placed between the opposing metal layers. A second resin layer is placed between the metal layer and the current collector terminal. The laminate film has an inner resin layer on the side of the metal layer facing the current collection terminal, A resin film is placed between the inner resin layer and the current collector 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 projection located at the corner of the current collection terminal, In the aforementioned welded portion, the inner surfaces of the laminate film are welded together via the protrusions. A battery in which, when the thickness of the first resin layer is Ta and the thickness of the second resin layer is Tb, Ta and Tb satisfy Ta > Tb.

2. The thickness of the metal layer in the welded portion is T ｃ In that case, the above T ａ and the T ｃ 0.5 ≤ T ａ / T ｃ The battery according to claim 1, satisfying ≤ 4.

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