Battery stack

Abstract

To facilitate bending a bundle including a plurality of current collector portions.SOLUTION: A plurality of first current collector portions 112a is pulled out from a laminated portion 100a. An exterior material 200 encases a battery element 100. A first tab 310 is connected to a plurality of first current collector portions 112a. The first current collector portion 112a between the laminated portion 100a and the first tab 310 has a first region RG1. In the first region RG1, the thickness of the bundle including the first current collector portion 112a in the third direction Z decreases from the laminated portion 100a to the first tab 310, and the rate of decrease in the thickness decreases from the laminated portion 100a to the first tab 310.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a battery and a method for manufacturing the battery. [Background technology]

[0002] In recent years, non-aqueous electrolyte secondary batteries, particularly lithium ion secondary batteries, have been developed. A lithium ion secondary battery includes a battery element having a positive electrode, a negative electrode, and a separator. The positive electrode, the negative electrode, and the separator form a laminated portion of the battery element. The lithium ion secondary battery further includes an exterior material that encases the battery element. A positive electrode current collector foil and a negative electrode current collector foil are drawn out from the positive electrode and the negative electrode of the laminated portion of the battery element, respectively. The positive electrode current collector foil and the negative electrode current collector foil are connected to a positive electrode tab and a negative electrode tab, respectively.

[0003] For example, a plurality of battery elements each wrapped in a housing material may be stacked, as described in Patent Document 1. Patent Document 1 describes bundling a plurality of tabs by folding each tab (positive electrode tab or negative electrode tab) pulled out from the housing material.

[0004] Patent Document 2 describes folding the exterior material together with the tab toward the battery element. Patent Document 2 also describes that by folding the exterior material together with the tab, the length of the exterior material in the direction in which the tab is pulled out can be shortened compared to when the exterior material is not folded, and that the volumetric energy density can be improved.

[0005] Patent Document 3 describes that by forming notches on both sides of the tab in the exterior material, the tab can be easily bent together with the exterior material. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2016 / 020999 [Patent Document 2] Japanese Patent Application Publication No. 11-260327 [Patent Document 3] International Publication No. 2019 / 150904 Summary of the Invention [Problem to be solved by the invention]

[0007] To shorten the length of the tab required for the tip to reach a specific position, the tab tip may be directed in a specific direction by bending a portion of the exterior material between the laminate and the tab, rather than bending the tab itself. In this case, it is necessary to bend a bundle including multiple current collector parts (positive electrode current collector foils or negative electrode current collector foils) that are pulled out from the laminate and located between the laminate and the tab. However, bending this bundle may cause the current collector parts (current collector foils) to break.

[0008] One object of the present invention is to make it easier to bend a bundle including a plurality of current collector parts. Other objects of the present invention will become apparent from the description of this specification. [Means for solving the problem]

[0009] One aspect of the present invention is a battery element including a laminated portion including a plurality of first electrodes, a plurality of second electrodes, and a plurality of separators, and a plurality of first current collector portions drawn out from the laminated portion; an exterior material that encases the battery element; a first tab connected to the plurality of first current collecting portions; Equipped with The battery has a first region in which the thickness of the bundle including the plurality of first current collector parts between the stack and the first tab decreases from the stack to the first tab, and the rate of decrease in thickness decreases from the stack to the first tab.

[0010] Another aspect of the present invention is A method for manufacturing a battery includes a step of bundling a plurality of first current collector parts pulled out from a laminate including a plurality of first electrodes, a plurality of second electrodes, and a plurality of separators toward a first tab, and joining the plurality of first current collector parts to the first tab while pressing at least a portion of the plurality of first current collector parts between the laminate and the first tab in the thickness direction of the bundle including the plurality of first current collector parts. [Effects of the Invention]

[0011] According to the above aspect of the present invention, it is possible to easily bend a bundle including a plurality of current collector portions. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a top view of the battery according to the embodiment. [Figure 2] FIG. 2 is a right side view of the battery shown in FIG. [Figure 3] FIG. 2 is a rear view of the battery shown in FIG. [Figure 4] FIG. 4 is an enlarged view of a region α shown in FIG. [Figure 5] 2 is an enlarged view of a first tab and its surroundings of the battery shown in FIG. 1. [Figure 6] 6 is a cross-sectional view taken along the line AA′ of FIG. 5. [Figure 7] 7A to 7C are diagrams for explaining an example of a method for manufacturing the battery shown in FIGS. 1 to 6. [Figure 8] 7A to 7C are diagrams for explaining an example of a method for manufacturing the battery shown in FIGS. 1 to 6. [Figure 9] FIG. 7 is a schematic diagram for explaining an example of application of the battery shown in FIGS. 1 to 6. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, like components are designated by like reference numerals, and the description thereof will be omitted as appropriate.

[0014] In this specification, ordinal numbers such as "first," "second," and "third" are used merely to distinguish between similarly named configurations, unless otherwise specified, and do not imply any particular characteristics (e.g., order or importance) of the configurations.

[0015] FIG. 1 is a top view of a battery 10 according to an embodiment. FIG. 2 is a right side view of the battery 10 shown in FIG. 1. FIG. 3 is a rear view of the battery 10 shown in FIG. 1. FIG. 4 is an enlarged view of region α shown in FIG. 3. FIG. 5 is an enlarged view of a first tab 310 and its surroundings of the battery 10 shown in FIG. 1. FIG. 6 is a cross-sectional view taken along line AA′ in FIG. 5.

[0016] The battery 10 includes a battery element 100, an exterior material 200, a first tab 310, and a second tab 320. The battery element 100 has a laminated portion 100a and a plurality of first current collector portions 112a. The laminated portion 100a includes a plurality of first electrodes 110, a plurality of second electrodes 120, and a plurality of separators 130.

[0017] 1 to 6, the first direction X is the length direction of the battery 10 (battery element 100). The positive direction of the first direction X (the direction indicated by the arrow indicating the first direction X) is the direction from the second tab 320 to the first tab 310, which is the front direction of the battery 10 (battery element 100). The negative direction of the first direction X (the direction opposite to the direction indicated by the arrow indicating the first direction X) is the direction from the first tab 310 to the second tab 320, which is the rear direction of the battery 10 (battery element 100). The second direction Y is a direction intersecting the first direction X, specifically, a direction perpendicular to the first direction X, which is the width direction of the battery 10 (battery element 100). The positive direction of the second direction Y (the direction indicated by the arrow indicating the second direction Y) is the right direction of the battery 10 when viewed from the positive direction of the first direction X. The negative direction of the second direction Y (the opposite direction to the direction indicated by the arrow indicating the second direction Y) is the left direction of the battery 10 when viewing the battery 10 from the positive direction of the first direction X. The third direction Z is a direction intersecting both the first direction X and the second direction Y, specifically, a direction perpendicular to both the first direction X and the second direction Y, and is the thickness (height) direction of the battery 10 (battery element 100). The positive direction of the third direction Z (the direction indicated by the arrow indicating the third direction Z) is the upward direction of the battery 10. The negative direction of the third direction Z (the opposite direction to the direction indicated by the arrow indicating the third direction Z) is the downward direction of the battery 10. The same applies to Figures 7 to 9 described below.

[0018] In FIG. 5, a fold C indicated by a dashed line indicates the position of a fold that is formed when the exterior material 200 is folded between the laminated portion 100a and the first tab 310.

[0019] In this embodiment, the battery 10 is a lithium ion secondary battery. However, the battery 10 may be a battery other than a lithium ion secondary battery.

[0020] An overview of the battery 10 will be described with reference to FIG.

[0021] The multiple first current collector portions 112a are respectively drawn out from the multiple first electrodes 110 of the laminated unit 100a toward the front of the laminated unit 100a (the positive direction of the first direction X). The exterior material 200 encases the battery element 100. The first tab 310 is connected to the multiple first current collector portions 112a. The multiple first current collector portions 112a between the laminated unit 100a and the first tab 310 have a first region RG1 and a second region RG2. The first region RG1 is located closer to the first tab 310 than the laminated unit 100a in the first direction X. The second region RG2 is located closer to the laminated unit 100a than the first region RG1 in the first direction X. Furthermore, the second region RG2 is located closer to the laminated unit 100a than the first tab 310 in the first direction X.

[0022] In the first region RG1, the thickness in the third direction Z of the bundle including the plurality of first current collector portions 112a (the distance in the third direction Z between two of the plurality of first current collector portions 112a located at both ends in the third direction Z) decreases nonlinearly from the laminate 100a to the first tab 310 (as it moves toward the positive direction of the first direction X). Specifically, in the first region RG1, the thickness in the third direction Z of the bundle including the plurality of first current collector portions 112a decreases from the laminate 100a to the first tab 310 (as it moves toward the positive direction of the first direction X), and the rate of decrease in thickness decreases from the laminate 100a to the first tab 310 (as it moves toward the positive direction of the first direction X). For example, in the first region RG1, the thickness in the third direction Z of the bundle including the plurality of first current collector portions 112a can be matched to or approximated by a downwardly convex function with the position in the first direction X as a variable.

[0023] In the second region RG2, the thickness in the third direction Z of the bundle including the plurality of first current collector portions 112a (the distance in the third direction Z between two of the plurality of first current collector portions 112a located at both ends in the third direction Z) decreases nonlinearly from the laminate 100a to the first tab 310 (as it moves toward the positive direction of the first direction X). Specifically, in the second region RG2, the thickness in the third direction Z of the bundle including the plurality of first current collector portions 112a decreases from the laminate 100a to the first tab 310 (as it moves toward the positive direction of the first direction X), and the rate of decrease in thickness increases from the laminate 100a to the first tab 310 (as it moves toward the positive direction of the first direction X). For example, in the second region RG2, the thickness in the third direction Z of the bundle including the plurality of first current collector portions 112a can be matched to or approximated by an upwardly convex function with the position in the first direction X as a variable.

[0024] In this embodiment, the thickness (in the third direction Z) of the bundle of the plurality of first current collector portions 112a in the first region RG1 near the first tab 310 can be made thinner than the thickness (in the third direction Z) of the bundle of the plurality of first current collector portions 112a near the first tab 310 in a case where each first current collector portion 112a extends straight from the laminated unit 100a to the first tab 310. In this case, even if the plurality of first current collector portions 112a are bent in the first region RG1 or in the vicinity of the first region RG1, the possibility of each first current collector portion 112a breaking is reduced compared to a case where each first current collector portion 112a extends straight from the laminated unit 100a to the first tab 310. Therefore, it is easy to bend the plurality of first current collector portions 112a so that the tip of the first tab 310 (the end on the positive side in the first direction X) is oriented in a specific direction. For example, the multiple first collector portions 112a and the outer casing material 200 are folded so that the first region RG1 of the multiple first collector portions 112a, or the region of the first collector portion 112a between the laminated portion 100a and the first tab 310 that is closer to the first tab 310 than the first region RG1, forms crease C (Figure 5).

[0025] The plurality of first current collector portions 112a between the laminate portion 100a and the first tab 310 may further have a region located on the first tab 310 side with respect to the first region RG1. In this region, the minimum value of the thickness in the third direction Z of the bundle including the plurality of first current collector portions 112a (the distance in the third direction Z between two first current collector portions 112a located at both ends in the third direction Z among the plurality of first current collector portions 112a) is, for example, 50% or more, 65% or more, 80% or more, or 95% or more of the maximum value of the thickness in the third direction Z of the bundle including the plurality of first current collector portions 112a.

[0026] The second current collecting portions (not shown) drawn from the second electrodes 120 toward the rear of the laminate 100a (the negative direction of the first direction X) and the second tab 320 may also have a relationship similar to that shown in FIG. 6. That is, the second current collecting portions (not shown) may have regions corresponding to the first region RG1 and the second region RG2, similar to the first current collecting portions 112a. Alternatively, the second current collecting portions (not shown) drawn from the second electrode 120 and the second tab 320 may have a relationship different from that shown in FIG. 6. For example, the second current collecting portions (not shown) may not have regions corresponding to the first region RG1 and the second region RG2.

[0027] The battery 10 will be described in detail with reference to FIGS.

[0028] The first tab 310 is located at the front of the battery 10 (positive direction in the first direction X), and the second tab 320 is located at the rear of the battery 10 (negative direction in the first direction X). However, the first tab 310 and the second tab 320 may be located on a common side of the battery 10, for example, at the front (positive direction in the first direction X) or rear (negative direction in the first direction X) of the battery 10. In this case, the first tab 310 and the second tab 320 are aligned in the second direction Y, for example.

[0029] The exterior packaging material 200 encases the battery element 100 together with an electrolyte solution (not shown). The exterior packaging material 200 has a first exterior packaging material sheet 210 and a second exterior packaging material sheet 220. The first exterior packaging material sheet 210 covers the upper surface (the surface on the positive side in the third direction Z) of the laminated unit 100a, and the second exterior packaging material sheet 220 covers the lower surface (the surface on the negative side in the third direction Z) of the laminated unit 100a. The first exterior packaging material sheet 210 and the second exterior packaging material sheet 220 are bonded to each other in an area surrounding the laminated unit 100a when viewed from the third direction Z. Furthermore, both sides of the laminated unit 100a in the second direction Y of the exterior packaging material 200 are folded back toward the laminated unit 100a. 4, the portion of the exterior packaging material 200 on the negative side in the second direction Y has a portion bent from the negative side in the second direction Y toward the positive side in the third direction Z, and a portion folded back from the folded portion and located on the positive side in the second direction Y with respect to the folded portion. However, the folded shape of the exterior packaging material 200 is not limited to the example shown in FIG. 4. Furthermore, the portion of the exterior packaging material 200 on the positive side in the second direction Y may have a shape similar to the shape shown in FIG. 4, or a shape different from the shape shown in FIG. 4. According to this embodiment, the volume of the battery 10 can be reduced and the volumetric energy density of the battery 10 can be improved compared to when the exterior packaging material 200 is not folded.

[0030] In this embodiment, both of the sides of the laminated portion 100a of the packaging material 200 in the second direction Y are folded back toward the laminated portion 100a. However, only one of the sides of the laminated portion 100a of the packaging material 200 in the second direction Y may be folded back toward the laminated portion 100a. In other words, at least one of the sides of the laminated portion 100a of the packaging material 200 in the second direction Y may be folded back toward the laminated portion 100a.

[0031] In this embodiment, the packaging material 200 has two packaging material sheets (a first packaging material sheet 210 and a second packaging material sheet 220). However, the packaging material 200 may have only one packaging material sheet. In this case, the packaging material sheet may be folded back over one of both sides in the second direction Y of the battery element 100 (the laminated portion 100a) so that a portion of the packaging material sheet covers the upper surface (the surface on the positive side in the third direction Z) of the laminated portion 100a and another portion of the packaging material sheet covers the lower surface (the surface on the negative side in the third direction Z) of the laminated portion 100a, and the portion of the packaging material sheet and the other portion of the packaging material sheet are bonded together.

[0032] A notch 202 is provided in the exterior packaging material 200 on each side of the first tab 310 in the second direction Y. The notches 202 are open in a direction from the laminated unit 100a toward the first tab 310 (the positive direction in the first direction X) and in directions from the first tab 310 toward both sides of the first tab 310 in the second direction Y (the negative direction in the second direction Y for the notch 202 on the left side (the negative side in the second direction Y), and the positive direction in the second direction Y for the notch 202 on the right side (the positive side in the second direction Y)). In this case, when the exterior packaging material 200 is folded along the fold C between the laminated unit 100a and the first tab 310, the notch 202 can serve as the starting point of the fold C of the exterior packaging material 200. Therefore, in this embodiment, the exterior packaging material 200 is easier to fold between the laminated unit 100a and the first tab 310 compared to when the notch 202 is not provided. Furthermore, when the notch 202 is provided, it is not necessary to fold the folded-back portions of the outer casing 200 on both sides in the second direction Y from the positive direction of the first direction X toward the positive or negative direction of the third direction Z. The folded-back portions of the outer casing 200 on both sides in the second direction Y are difficult to fold from the positive direction of the first direction X toward the positive or negative direction of the third direction Z. However, in the present embodiment, as described above, it is not necessary to fold the folded-back portions of the outer casing 200 on both sides in the second direction Y. Therefore, in the present embodiment, it is easier to fold the outer casing 200 between the laminated portion 100a and the first tab 310 compared to when the notch 202 is not provided.

[0033] In the direction from the first tab 310 toward the laminated unit 100a (the negative direction of the first direction X), the edge of the notch 202 on the laminated unit 100a side is located closer to the first tab 310 than the first region RG1 of the plurality of first current collector portions 112a. In this case, the distance between the edge of the notch 202 on the laminated unit 100a side and the front surface of the laminated unit 100a (the surface on the positive side in the first direction X) can be made larger than when the edge of the notch 202 on the laminated unit 100a side is aligned with the first region RG1 of the plurality of first current collector portions 112a or is located closer to the laminated unit 100a than the first region RG1 in the direction from the first tab 310 toward the laminated unit 100a (the negative direction of the first direction X). Therefore, it is possible to reduce deterioration in the sealing performance of the exterior material 200 due to the provision of the notch 202. However, in the direction from the first tab 310 side toward the laminated portion 100a side (the negative direction of the first direction X), the edge of the notch 202 on the laminated portion 100a side may be aligned with the first region RG1 of the multiple first collector portions 112a, or may be located on the laminated portion 100a side relative to the first region RG1.

[0034] The end of the left (negative side in the second direction Y) notch 202 of the two notches 202 on the first tab 310 side is located closer to the left (negative side in the second direction Y) end of the first tab 310 in the second direction Y than the left (negative side in the second direction Y) end (left side surface) of the laminated unit 100a. In this case, the length of the fold C can be made shorter than when the end of the left (negative side in the second direction Y) notch 202 of the left (negative side in the second direction Y) notch 202 on the first tab 310 side is located closer to the left (negative side in the second direction Y) end (left side surface) of the laminated unit 100a in the second direction Y than the left (negative side in the second direction Y) end of the first tab 310. However, the end of the left (negative side in the second direction Y) notch 202 on the first tab 310 side may be located closer to the left (negative side in the second direction Y) end (left side surface) of the laminate 100a in the second direction Y than the left (negative side in the second direction Y) end of the first tab 310. Alternatively, the end of the left (negative side in the second direction Y) notch 202 on the first tab 310 side may be located equidistant in the second direction Y from the left (negative side in the second direction Y) end of the first tab 310 and the left (negative side in the second direction Y) end (left side surface) of the laminate 100a. The same applies to the end of the right (positive side in the second direction Y) notch 202 on the first tab 310 side.

[0035] The region where the notch 202 is provided is not limited to this embodiment. For example, the notch 202 may be provided on only one of both sides of the first tab 310 of the exterior material 200 in the second direction Y. That is, the notch 202 may be provided on at least one of both sides of the first tab 310 of the exterior material 200 in the second direction Y. Even when the notch 202 is provided on only one of both sides of the first tab 310 of the exterior material 200 in the second direction Y, the exterior material 200 can be easily bent compared to a case where the notch 202 is not provided.

[0036] The direction in which the notches 202 are open is not limited to this embodiment. For example, the notches 202 do not have to open in directions from the first tab 310 to both sides of the first tab 310 in the second direction Y (the negative direction in the second direction Y for the notch 202 on the left side (the negative side in the second direction Y) and the positive direction in the second direction Y for the notch 202 on the right side (the positive side in the second direction Y)), but may open only in the direction from the laminated unit 100a side to the first tab 310 side (the positive direction in the first direction X). Even in this case, it is possible to make the exterior material 200 easier to bend between the laminated unit 100a and the first tab 310 compared to when the notches 202 are not provided.

[0037] The notches 202 on both sides of the second tab 320 of the exterior material 200 in the second direction Y may be the same as the notches 202 on the first tab 310 side, or may be different from the notches 202 on the first tab 310 side. Alternatively, the notches 202 may not be provided on at least one of the first tab 310 side and the second tab 320 side.

[0038] The battery element 100 will be described in detail with reference to FIG.

[0039] The first electrode 110 and the second electrode 120 have opposite polarities. The first electrode 110, the first current collector 112, the first active material layer 114, the second electrode 120, the second current collector 122, and the second active material layer 124 are respectively a positive electrode, a positive electrode current collector, and a positive electrode active material layer, and a negative electrode, a negative electrode current collector, and a negative electrode active material layer. However, the first electrode 110, the first current collector 112, the first active material layer 114, the second electrode 120, the second current collector 122, and the second active material layer 124 may also be respectively a negative electrode, a negative electrode current collector, and a negative electrode active material layer, and a positive electrode, a positive electrode current collector, and a positive electrode active material layer.

[0040] The first electrode 110 has a first current collector 112 and a first active material layer 114. In this embodiment, the first active material layer 114 is located on both the upper surface (the surface on the positive side in the third direction Z) and the lower surface (the surface on the negative side in the third direction Z) of the first current collector 112. However, the first active material layer 114 may be located on only one of the upper surface and the lower surface of the first current collector 112.

[0041] The second electrode 120 has a second current collector 122 and a second active material layer 124. In this embodiment, the second active material layer 124 is located on both the upper surface (the surface on the positive side in the third direction Z) and the lower surface (the surface on the negative side in the third direction Z) of the second current collector 122. However, the second active material layer 124 may be located on only one of the upper surface and the lower surface of the second current collector 122.

[0042] The separator 130 is located between the first electrode 110 and the second electrode 120 that are adjacent to each other in the third direction Z. The separator 130 is provided to prevent contact (i.e., short circuit) between the first electrode 110 and the second electrode 120 that are adjacent to each other in the third direction Z.

[0043] The laminated portion 100a has a plurality of first electrodes 110, second electrodes 120, and separators 130 stacked in the third direction Z. The plurality of first electrodes 110 and the plurality of second electrodes 120 are alternately stacked along the third direction Z such that the separators 130 are located between adjacent first electrodes 110 and second electrodes 120.

[0044] The first current collector portion 112a is connected to the first current collector 112 of the battery element 100. Specifically, the first current collector 112 and the first current collector portion 112a form an integrated conductive portion (conductive foil). In other words, this conductive portion (conductive foil) serves as the first current collector 112 of the first electrode 110 in a region where it overlaps with the second electrode 120 and the separator 130 in the third direction Z, and serves as the first current collector portion 112a on the outside of the laminated unit 100a (on the positive side of the laminated unit 100a in the first direction X). The same applies to a second current collector portion (not shown) drawn from the second electrode 120 toward the rear of the laminated unit 100a (in the negative direction of the first direction X).

[0045] Figures 7 and 8 are diagrams for explaining an example of a method for manufacturing the battery 10 shown in Figures 1 to 6. Figure 7 corresponds to Figure 6. Figure 8 corresponds to Figure 1.

[0046] First, the battery element 100 is formed. The battery element 100 is formed by alternately stacking a plurality of first electrodes 110 and a plurality of second electrodes 120 such that a separator 130 is disposed between adjacent first electrodes 110 and second electrodes 120.

[0047] Next, as shown in FIG. 7, the multiple first current collector portions 112a are bundled together in a first tab 310, and the multiple first current collector portions 112a are joined to the first tab 310 while at least a portion of the multiple first current collector portions 112a is pressed in the thickness direction (third direction Z) of the bundle including the multiple first current collector portions 112a by a first jig J1 and a second jig J2 between the laminated portion 100a and the first tab 310.

[0048] At least a portion of the first current collector portions 112a are pressed in the thickness direction (third direction Z) of the bundle including the first current collector portions 112a by placing the first current collector portions 112a on the second jig J2 and pressing the first jig J1 from above (positive direction in the third direction Z) to below (negative direction in the third direction Z) the first current collector portions 112a. In this case, the portions of the first current collector portions 112a pressed in the thickness direction (third direction Z) do not need to be subjected to a joining process such as welding, so that distortion, as described below, remains. However, the method of pressing the first current collector portions 112a is not limited to the method according to this embodiment.

[0049] The plurality of first current collector portions 112a are joined to the first tab 310 by welding such as heat welding or ultrasonic welding.

[0050] In this embodiment, each first current collector portion 112a is joined to the first tab 310 in a state in which it is distorted (i.e., a force that applies this distortion) into a shape that extends straight from the laminate portion 100a toward the first tab 310. Even after this force is released (e.g., after the first jig J1 and the second jig J2 are separated from the multiple first current collector portions 112a), the distortion applied to each first current collector portion 112a remains. As a result, a first region RG1 and a second region RG2 (FIG. 6) are formed.

[0051] A plurality of second current collector portions (not shown) respectively drawn out from the plurality of second electrodes 120 toward the rear of the laminated portion 100a (the negative direction of the first direction X) can also be joined to the second tab 320 in the same manner as described using Figure 7.

[0052] Next, as shown in Fig. 8, the upper surface (the surface on the positive side in the third direction Z) of the laminated portion 100a is covered with the first exterior material sheet 210, and the lower surface (the surface on the negative side in the third direction Z) of the laminated portion 100a is covered with the second exterior material sheet 220. Next, in the area surrounding the laminated portion 100a as viewed from the third direction Z, the first exterior material sheet 210 and the second exterior material sheet 220 are joined to each other by, for example, welding. Next, notches 202 (for example, Fig. 1) are formed in the four corners of the exterior material 200. Next, as shown in Fig. 4, both sides of the laminated portion 100a of the exterior material 200 in the second direction Y are folded back toward the laminated portion 100a.

[0053] In this manner, the battery 10 is manufactured.

[0054] Fig. 9 is a schematic diagram for explaining an example of an application of the battery 10 shown in Fig. 1 to Fig. 6. An example of an application of the battery 10 will be explained using Fig. 9 with reference to Figs.

[0055] In this example, multiple batteries 10 (battery elements 100) are stacked along the thickness direction of each battery 10 (third direction Z). The multiple first current collector portions 112a and exterior material 200 of each battery 10 (battery element 100) are folded along fold C. The first tabs 310 of each battery 10 (battery element 100) are located in front of each battery element 100 (positive side in the first direction X) and are bundled together at a location located at the center of the multiple batteries 10 (multiple battery elements 100) in the third direction Z.

[0056] The multiple first current collector portions 112a and the exterior packaging material 200 of each battery 10 (battery element 100) are bent so that the tips (ends on the positive side of the first direction X) of the first tabs 310 are oriented in different directions relative to the direction from the stacked portion 100a toward the first tabs 310 (the positive direction of the first direction X). In the example shown in Fig. 9, the tips (ends on the positive side of the first direction X) of the first tabs 310 of the first-tier battery 10 (battery element 100) are oriented in a direction tilted by a predetermined angle from the positive direction of the first direction X toward the positive direction of the third direction Z from the positive direction of the first direction X. The tip (end on the positive side in the first direction X) of the first tab 310 of the second-stage battery 10 (battery element 100) as it faces from the negative side to the positive side in the third direction Z is tilted at an angle from the positive side in the first direction X toward the positive side in the third direction Z, with respect to the positive side in the first direction X, smaller than the predetermined angle of the first tab 310 of the first-stage battery 10 (battery element 100). The tip (end on the positive side in the first direction X) of the first tab 310 of the third-stage battery 10 (battery element 100) as it faces from the negative side to the positive side in the third direction Z is tilted at an angle from the positive side in the first direction X toward the negative side in the third direction Z, with respect to the positive side in the first direction X, by a predetermined angle. The tip (end on the positive side of the first direction X) of the first tab 310 of the fourth-stage battery 10 (battery element 100) is tilted from the negative side of the third direction Z to the positive side of the third direction Z by an angle greater than the above-mentioned predetermined angle of the first tab 310 of the third-stage battery 10 (battery element 100) relative to the positive side of the first direction X.

[0057] Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various other configurations can also be adopted. Below, examples of reference forms are added. 1. A battery element having a laminated portion including a plurality of first electrodes, a plurality of second electrodes, and a plurality of separators, and a plurality of first current collector portions drawn out from the laminated portion; an exterior material that encases the battery element; a first tab connected to the plurality of first current collecting portions; Equipped with the plurality of first current collector parts between the stack and the first tab have a first region in which the thickness of the bundle including the plurality of first current collector parts decreases from the stack to the first tab, and the rate of decrease in thickness decreases from the stack to the first tab. 2. In the battery described in 1., the plurality of first current collector parts between the stack and the first tab are located on the stack side of the first region, and the battery has a second region in which the thickness of the bundle including the plurality of first current collector parts decreases from the stack to the first tab, and the rate of decrease in thickness increases from the stack to the first tab. 3. The battery according to 1. or 2., The battery, wherein the exterior material has a notch that opens in a direction from the laminated portion side toward the first tab side, on at least one of both sides of the first tab. 4. In the battery according to 3., In a direction from the first tab side toward the stacked portion side, the edge of the notch on the stacked portion side is located on the first tab side relative to the first regions of the plurality of first current collector portions. 5. The battery according to 3. or 4., The battery, wherein the notches open in a direction from the first tab toward both sides of the first tab. 6. The battery according to any one of 3. to 5., A battery, wherein at least one of the exterior materials on both sides of the laminated portion is folded back toward the laminated portion. 7. The battery according to any one of 1. to 6., the plurality of first current collector parts and the exterior material are folded so that the first regions of the plurality of first current collector parts, or the region of the plurality of first current collector parts between the laminated part and the first tab that is closer to the first tab than the first regions, forms a crease. 8. The battery according to 7., a plurality of the battery elements stacked on top of one another; a battery in which the plurality of first current collector portions and the exterior material of each battery element are folded so that the tips of the first tabs of each battery element are oriented in different directions relative to the direction from the stacked portion toward the first tabs. 9. A method for manufacturing a battery, comprising a step of bundling a plurality of first current collector parts pulled out from a laminate including a plurality of first electrodes, a plurality of second electrodes, and a plurality of separators toward a first tab, and joining the plurality of first current collector parts to the first tab while pressing at least a portion of the plurality of first current collector parts between the laminate and the first tab in the thickness direction of the bundle including the plurality of first current collector parts. [Explanation of symbols]

[0058] 10 batteries 100 Battery Elements 100a laminated section 110 1st electrode 112 First current collector 112a First current collector part 114 First active material layer 120 2nd electrode 122 Second current collector 124 Second active material layer 130 Separator 200 Exterior materials 202 Notch 210 First exterior material sheet 220 Second exterior material sheet 310 First Tab 320 Second Tab C fold J1 First jig J2 Second jig RG1 1st area RG2 2nd area X 1st direction Y Second direction Z 3rd direction

Claims

1. a plurality of batteries stacked on top of one another; Each of the plurality of batteries a battery element including a plurality of first electrodes, a plurality of second electrodes, and a separator located between the plurality of first electrodes and the plurality of second electrodes, the battery element having a stacked portion in which the plurality of first electrodes, the plurality of second electrodes, and the separator are stacked in a predetermined stacking direction, and a plurality of first current collector portions drawn out from one side of the stacked portion in a direction perpendicular to the stacking direction; an exterior material that encases the battery element; a first tab having a base end located on a side where the battery element is located and connected to the plurality of first current collector portions; and In each of the plurality of batteries, the plurality of first current collector parts and the exterior material are folded so that regions of the plurality of first current collector parts and the exterior material that are located between the laminated portion and the base end of the first tab form creases, In each of the plurality of batteries, at least a portion including the base end of the first tab is inclined with respect to the direction perpendicular to the stacking direction by folding the plurality of first current collector portions and the exterior material, In each of the plurality of batteries, the plurality of first current collector portions between the stacked portion and the first tab have a first region in which a thickness of a bundle including the plurality of first current collector portions decreases from the stacked portion to the first tab, and a rate of decrease in the thickness decreases from the stacked portion to the first tab; a battery stack in which, in each of the plurality of batteries, the folds of the plurality of first current collector parts are located in one of the first regions of the plurality of first current collector parts and a region of the plurality of first current collector parts that is on the first tab side relative to the first region.

2. The battery stack according to claim 1 , a battery stack, wherein in each of the plurality of batteries, the plurality of first current collector portions between the stack portion and the first tab are located on the stack portion side with respect to the first region, and the stack has a second region in which the thickness of the bundle including the plurality of first current collector portions decreases from the stack portion to the first tab, and the rate of decrease in thickness increases from the stack portion to the first tab.

3. The battery stack according to claim 1 or 2, A battery stack, wherein in each of the plurality of batteries, a notch that opens in a direction from the stacked portion side toward the first tab side is provided in at least one of the exterior materials on both sides of the first tab.

4. The battery stack according to claim 3 , a battery stack in which, in each of the plurality of batteries, in a direction from the first tab side toward the stacking portion side, the edge of the notch on the stacking portion side is located on the first tab side relative to the first regions of the plurality of first current collector portions.

5. The battery stack according to claim 3 or 4, a battery stack, wherein in each of the plurality of batteries, the notch is open in a direction from the first tab toward both sides of the first tab.

6. The battery stack according to any one of claims 3 to 5, In each of the plurality of batteries, at least one of the exterior materials on both sides of the stacked portion is folded back toward the stacked portion.

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