Battery

Abstract

To improve the breaking resistance of a film.SOLUTION: The film 200 has a first accommodating portion 210 and a second accommodating portion 220. The first accommodation portion 210 covers one side of the battery element 100. The second accommodation portion 220 covers the other side opposite to the one side of the battery element 100. A recessed portion 232 is formed in a portion of the film 200 that is folded back from one of the first accommodating portion 210 and the second accommodating portion 220 to the other. The recessed portion 232 is recessed toward the battery element 100. In addition, the concave portion 232 extends along one direction orthogonal to the direction from the one side to the other side of the battery element 100.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a battery, a method for manufacturing a film, and a method for manufacturing a 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 and the negative electrode are separated by the separator. The battery element is enclosed in a film.

[0003] Patent Document 1 describes an example of a film. This film has one recess for covering one side of a battery element and another recess for covering the other side of the battery element, so as to prevent wrinkles from forming in the film when the film is wrapped around a large battery element. These two recesses are formed by placing the film between a die and two punches and forcing the two punches into the die. When the two punches are forced into the die, the film is sandwiched between the two punches in the thickness direction of the film by the bead and the die. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-71301 Summary of the Invention [Problem to be solved by the invention]

[0005] As described in Patent Document 1, two recesses may be formed in a film. For example, in Patent Document 1, as described above, when two recesses are formed in a film by forcing two punches into a die through the film, a force is applied to the film from both sides of the film in the thickness direction between the two punches. However, the present inventors have found that this method can affect the break resistance of the film.

[0006] One object of the present invention is to improve the break resistance of a film. Other objects of the present invention will become apparent from the description herein. [Means for solving the problem]

[0007] One aspect of the present invention is a battery element having a positive electrode, a negative electrode, and a separator; a film having a first housing portion covering one side of the battery element and a second housing portion covering the other side of the battery element opposite to the one side; Preparation, The battery has a recess in the portion of the film that is folded from one side of the first storage section to the other of the second storage section, which recess is recessed toward the battery element and extends along a direction perpendicular to the direction from one side of the battery element to the other side.

[0008] Another aspect of the present invention is a step of placing a film between a first mold having a first opening and a second opening and a second mold having a first block and a second block, and forming a first storage portion in the film by inserting the first block of the second mold into the first opening of the first mold, and forming a second storage portion in the film by inserting the second block of the second mold into the second opening of the first mold, the first mold is located between the first opening and the second opening and has a protruding portion whose tip is curved convexly toward the tip, This is a film manufacturing method in which the process of forming the first storage section and the second storage section includes a process of contacting the film with the tip of the protrusion of the first mold without applying pressure to the film from the opposite side of the protrusion of the first mold.

[0009] Yet another aspect of the present invention is A method for producing the film according to the above aspect; a step of folding the film from one of the first housing portion and the second housing portion to the other, so that one side of a battery element having a positive electrode, a negative electrode, and a separator is covered with the first housing portion of the film, and the other side of the battery element opposite to the one side is covered with the second housing portion of the film; The method for manufacturing a battery includes the steps of: [Effects of the Invention]

[0010] According to the above aspect of the present invention, the break resistance of the film can be improved. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a top view of the battery according to the embodiment. [Figure 2] FIG. 2 is a side view of the battery shown in FIG. [Figure 3] 2 is a cross-sectional view along AA' in FIG. [Figure 4] FIG. 4 is an exploded perspective view of an example of the battery element shown in FIGS. 1 to 3. [Figure 5] FIG. 5 is a plan view of an apparatus for manufacturing (processing) a film for the battery described with reference to FIGS. 1 to 4. [Figure 6] FIG. 6 is a cross-sectional view of FIG. 5 along BB'. [Figure 7] FIG. 7 is an enlarged view of an area α surrounded by a dashed line in FIG. 6. [Figure 8] 8A to 8C are diagrams for explaining an example of a method for wrapping a battery element with a film manufactured (processed) by the apparatus shown in FIGS. 5 to 7 (that is, a method for manufacturing a battery). [Figure 9] FIG. 2 is a diagram for explaining a method for producing (processing) a film according to a comparative example. [Figure 10] FIG. 4 is a diagram for explaining the positions at which the thickness of a film was measured. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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.

[0013] 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.

[0014] Fig. 1 is a top view of a battery 10 according to an embodiment. Fig. 2 is a side view of the battery 10 shown in Fig. 1. Fig. 3 is a cross-sectional view taken along line AA' in Fig. 1. Fig. 4 is an exploded perspective view of an example of the battery element 100 shown in Figs. 1 to 3.

[0015] 1 to 4, 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 lead 122 (described later) to the first lead 112 (described later). 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 lead 112 to the second lead 122. The second direction Y is a direction intersecting the first direction X, specifically, a direction perpendicular to the first direction X, and 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 rightward 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 direction opposite to the direction indicated by the arrow indicating the second direction Y) is the leftward direction of the battery 10 when viewed 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 direction opposite to the direction indicated by the arrow indicating the third direction Z) is the downward direction of the battery 10.

[0016] 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.

[0017] An overview of the battery 10 will be described using FIG. 3. The battery 10 includes a battery element 100 and a film 200. The battery element 100 includes a positive electrode 110, a negative electrode 120, and a separator 130. The film 200 includes a first housing section 210 and a second housing section 220. The first housing section 210 covers one side of the battery element 100 (the positive side in the third direction Z). The second housing section 220 covers the other side of the battery element 100 opposite the one side (the negative side in the third direction Z). A recess 232 is formed in the portion of the film 200 that is folded back from one side of the first housing section 210 and the second housing section 220 to the other. The recess 232 is recessed toward the battery element 100 (toward the negative side in the second direction Y). In addition, the recess 232 extends along a direction (first direction X (e.g., Figure 1 or Figure 2)) perpendicular to the direction from the one side of the battery element 100 to the other side (the negative direction of the third direction Z).

[0018] The recesses 232 in the film 200 are provided by a method described below with reference to Figures 5 to 8. As described below, the film 200 manufactured by the method described with reference to Figures 5 to 8 has high break resistance.

[0019] The battery 10 will be described in detail with reference to FIGS.

[0020] The battery element 100 includes a plurality of positive electrodes 110, a plurality of negative electrodes 120, and a plurality of separators 130. As shown in FIG. 4 , in this embodiment, the plurality of positive electrodes 110 and the plurality of negative electrodes 120 are alternately arranged along the third direction Z such that a separator 130 is disposed between adjacent positive electrodes 110 and negative electrodes 120. That is, the battery element 100 is a laminate including a plurality of positive electrodes 110, a plurality of negative electrodes 120, and a plurality of separators 130 stacked on one another. However, the structure of the battery element 100 is not limited thereto. For example, the separator 130 may be folded back along the second direction Y on the outer side of the positive electrodes 110 or negative electrodes 120 in the second direction Y, and extend in a zigzag manner so as to pass between adjacent positive electrodes 110 and negative electrodes 120. Alternatively, the battery element 100 may have only one positive electrode 110, only one negative electrode 120, and only one separator 130. Alternatively, at least one positive electrode 110, at least one negative electrode 120, and at least one separator 130 may be wound together.

[0021] The positive electrode 110 and the negative electrode 120 are connected to a first lead 112 and a second lead 122, respectively. As shown in FIGS. 1 and 2, in this embodiment, the first lead 112 and the second lead 122 are located on opposite sides of each other in the first direction X. However, the first lead 112 and the second lead 122 may be located on the same side of each other in the first direction X (for example, on the positive side of the first direction X or the negative side of the first direction X).

[0022] The film 200 accommodates the battery element 100 together with an electrolyte (not shown). That is, the film 200 functions as an exterior material.

[0023] The film 200 has, for example, a heat-sealable resin layer and a barrier layer, and may be, for example, a laminated film including a heat-sealable resin layer and a barrier layer. The resin material forming the heat-sealable resin layer may be, for example, polyethylene (PE), polypropylene, nylon, polyethylene terephthalate (PET), etc. The barrier layer has barrier properties, such as preventing leakage of the electrolyte or intrusion of moisture from the outside, and may be, for example, a barrier layer formed of a metal such as stainless steel (SUS) foil, aluminum foil, aluminum alloy foil, copper foil, or titanium foil.

[0024] The film 200 is folded back on the right side (positive side in the second direction Y) of the battery element 100 from one of the upper surface (positive side in the third direction Z) and the lower surface (negative side in the third direction Z) of the battery element 100 to the other. A recess 232 is formed in the folded portion of the film 200 that covers the right side surface (positive side in the second direction Y) of the battery element 100. In a region forward (positive side in the first direction X) of the front surface (positive side in the first direction X) of the battery element 100, the film 200 is folded back so as to sandwich the first lead 112 in the third direction Z. In this region, the fold of the film 200 (the end of the film 200 on the positive side in the second direction Y) protrudes to the right (positive side in the second direction Y) of the right side surface (positive side in the second direction Y) of the battery element 100. In a region behind (on the negative side in the first direction X) the rear surface (surface on the negative side in the first direction X) of the battery element 100, the film 200 is folded back so as to sandwich the second lead 122 in the third direction Z. In addition, in this region, the fold of the film 200 (the end of the film 200 on the positive side in the second direction Y) protrudes to the right (positive side in the second direction Y) of the right side surface (surface on the positive side in the second direction Y) of the battery element 100.

[0025] In a region to the left (negative side in the second direction Y) of the folded portion of the film 200 (the end of the film 200 on the positive side in the second direction Y), a portion of the film 200 (the portion covering the upper surface (the surface on the positive side in the third direction Z) of the battery element 100 and its surrounding portion) and another portion of the film 200 (the portion covering the lower surface (the surface on the negative side in the third direction Z) of the battery element 100 and its surrounding portion) overlap in the third direction Z. When viewed from the third direction Z, this portion of the film 200 and the other portion of the film 200 are bonded together by, for example, welding, except for the portion overlapping with the first lead 112 or the second lead 122 in the region surrounding the battery element 100. As a result, the battery element 100 is sealed by the film 200.

[0026] As shown in FIG. 3 , the recess 232 is curved convexly toward the battery element 100 (toward the negative direction in the second direction Y). The curved shape of the recess 232 is determined by the curved shape of the tip of the protrusion 316, which will be described later. The recess 232 also has a depth D. The depth D of the recess 232 is the distance in the second direction Y between the portion of the film 200 that covers the right side surface (the surface on the positive side in the second direction Y) of the battery element 100 and protrudes most toward the right side (the positive side in the second direction Y) of the battery element 100, and the portion of the film 200 that covers the right side surface (the surface on the positive side in the second direction Y) of the battery element 100 and is most recessed toward the battery element 100 side (the negative side in the second direction Y).

[0027] 2, when viewed from the right side of the battery 10 (the positive side in the second direction Y), the recess 232 extends continuously along the first direction X from one side of the front surface of the battery element 100 (the surface on the positive side in the first direction X) or its vicinity to the other side of the rear surface of the battery element 100 (the surface on the negative side in the first direction X) or its vicinity. The depth D of the recess 232 becomes shallower with increasing distance from the center of the battery element 100 in the first direction X. This is because the folds of the film 200 (the end of the film 200 on the positive side in the second direction Y) on the front side (positive side in the first direction X) and rear side (negative side in the first direction X) of the battery element 100 protrude to the right (positive side in the second direction Y) of the right side (surface on the positive side in the second direction Y) of the battery element 100, causing the portion of the film 200 covering the right side (surface on the positive side in the second direction Y) of the battery element 100 to be pulled in the positive direction in the second direction Y.

[0028] Fig. 5 is a plan view of an apparatus 300 for manufacturing (processing) the film 200 of the battery 10 described with reference to Figs. 1 to 4. Fig. 6 is a cross-sectional view taken along line BB' in Fig. 5. Fig. 7 is an enlarged view of the area α surrounded by the dashed line in Fig. 6.

[0029] 5 to 7 , the fourth direction P is the length direction of each of the first block 322 and the second block 324 described later. The positive direction of the fourth direction P (the direction indicated by the arrow indicating the fourth direction P) is the rightward direction of each of the first block 322 and the second block 324 when viewed from the negative direction of the fifth direction Q described later. The negative direction of the fourth direction P (the opposite direction to the direction indicated by the arrow indicating the fourth direction P) is the leftward direction of each of the first block 322 and the second block 324 when viewed from the negative direction of the fifth direction Q described later. The fifth direction Q is a direction intersecting the fourth direction P, specifically, a direction perpendicular to the fourth direction P, and is the width direction of each of the first block 322 and the second block 324. The positive direction of the fifth direction Q (the direction indicated by the arrow indicating the fifth direction Q) is the direction from the second block 324 toward the first block 322. The negative direction of the fifth direction Q (the opposite direction to the direction indicated by the arrow indicating the fifth direction Q) is the direction from the first block 322 to the second block 324. The sixth direction R is a direction intersecting both the fourth direction P and the fifth direction Q, specifically, a direction perpendicular to both the fourth direction P and the fifth direction Q, and is the thickness (height) direction of the first block 322 and the second block 324. The positive direction of the sixth direction R (the direction indicated by the arrow indicating the sixth direction R) is the direction (upward) from the first mold 310 to the second mold 320 described below. The negative direction of the sixth direction R (the opposite direction to the direction indicated by the arrow indicating the sixth direction R) is the direction (downward) from the second mold 320 to the first mold 310.

[0030] An example of a manufacturing (processing) method for the film 200 will be outlined below with reference to FIGS. 5 to 7. The film 200 is manufactured using an apparatus 300. The apparatus 300 includes a first mold 310 and a second mold 320. The first mold 310 has a first opening 312, a second opening 314, and a protrusion 316. The protrusion 316 is located between the first opening 312 and the second opening 314. The tip (upper end) of the protrusion 316 (the end on the positive side of the sixth direction R) is curved convexly toward the tip (upward) of the protrusion 316 (the positive direction of the sixth direction R). The second mold 320 includes a first block 322 and a second block 324. The manufacturing (processing) method of the film 200 includes the steps of placing the film 200 between a first mold 310 and a second mold 320, inserting a first block 322 of the second mold 320 into a first opening 312 of the first mold 310 to form a first storage section 210 (first recess) in the film 200, and inserting a second block 324 of the second mold 320 into a second opening 314 of the first mold 310 to form a second storage section 220 (second recess) in the film 200. The step of forming the first storage section 210 and the second storage section 220 includes the step of bringing the film 200 into contact with the tip of the protrusion 316 of the first mold 310 without applying pressure to the film 200 from the side opposite the protrusion 316 of the first mold 310 (the upper side of the protrusion 316, i.e., the positive side of the protrusion 316 in the sixth direction R).

[0031] The manufacturing (processing) method of the film 200 will be described in detail with reference to FIGS.

[0032] 5 to 7, the first mold 310 is a die, and the first block 322 and the second block 324 are each a punch.

[0033] First, the film 200 is placed on the first mold 310 so as to overlap both the first opening 312 and the second opening 314 of the first mold 310 .

[0034] Next, the portions of the film 200 located around both the first opening 312 and the second opening 314 of the first mold 310 are pressed toward the first mold 310 by a third block 330 (e.g., a stopper). This fixes the film 200 to the first mold 310.

[0035] Next, the first block 322 and the second block 324 of the second mold 320 are moved from above (the positive direction of the sixth direction R) to below (the negative direction of the sixth direction R) so as to enter the first opening 312 and the second opening 314 of the first mold 310, respectively. At this time, the first block 322 moves until its lower surface (the surface on the negative side in the sixth direction R) reaches a position lower (the negative side in the sixth direction R) than the upper end (the end on the positive side in the sixth direction R) of the protrusion 316. Similarly, the second block 324 moves until its lower surface (the surface on the negative side in the sixth direction R) reaches a position lower (the negative side in the sixth direction R) than the upper end (the end on the positive side in the sixth direction R) of the protrusion 316. As a result, in the regions where the film 200 overlaps with the first block 322 and the second block 324 in the sixth direction R, a first storage section 210 and a second storage section 220 are formed in the film 200. Furthermore, between the first block 322 and the second block 324, the film 200 is pulled along the curvature of the tip (upper end) (end on the positive side in the sixth direction R) of the protrusion 316, and a recess 232 is formed in the film 200. Furthermore, while the film 200 is pulled along the curvature of the tip (upper end) (end on the positive side in the sixth direction R) of the protrusion 316, the film 200 is not pressed by a pressing member such as a stopper from the opposite side of the protrusion 316 (the upper side of the protrusion 316, i.e., the positive side of the protrusion 316 in the sixth direction R).

[0036] If the tip (upper end) of the protrusion 316 is not curved but has a corner (for example, if the top surface of the protrusion 316 is a flat surface parallel to the fifth direction Q and a corner is formed between this flat surface and the side surfaces of the protrusion 316 on both sides in the fifth direction Q, or if the tip (upper end) of the protrusion 316 protrudes in a triangular shape), force may be locally concentrated at a portion of the film 200 that contacts the corner of the protrusion 316. In this case, the thickness of that portion of the film 200 may be locally thin. Therefore, the break resistance of that portion of the film 200 may be locally deteriorated. In contrast, in this embodiment, a substantially uniform force is applied to the film 200 along the curvature of the tip (upper end) of the protrusion 316 (the end on the positive side in the sixth direction R). Therefore, it is possible to suppress a decrease in the break resistance of the portion of the film 200 where the recess 232 is provided.

[0037] If the film 200 is pressed by a pressing member such as a stopper from the opposite side of the protrusion 316 (the upper side of the protrusion 316, i.e., the positive side of the protrusion 316 in the sixth direction R) while the film 200 is being pulled along the curvature of the tip (upper end) of the protrusion 316 (the end on the positive side of the sixth direction R), the thickness of the portion of the film 200 that is in contact with both the protrusion 316 and the pressing member may be locally thin. Therefore, the break resistance of that portion of the film 200 may be locally deteriorated. In contrast, in the present embodiment, the film 200 is not pressed by a pressing member such as a stopper from the opposite side of the protrusion 316 (the upper side of the protrusion 316, i.e., the positive side of the protrusion 316 in the sixth direction R) while the film 200 is being pulled along the curvature of the tip (upper end) of the protrusion 316 (the end on the positive side of the sixth direction R). Therefore, it is possible to prevent a decrease in the break resistance of the portion of film 200 where recesses 232 are provided.

[0038] When viewed from the fourth direction P, the tip (top end) of the protrusion 316 (the end on the positive side in the sixth direction R) may be curved, for example, in an arc shape. In this case, the diameter of this arc may be substantially equal to the width of the protrusion 316 in the fifth direction Q, and may be, for example, 90% to 110% of the width of the protrusion 316 in the fifth direction Q. Alternatively, when viewed from the fourth direction P, the tip (top end) of the protrusion 316 (the end on the positive side in the sixth direction R) may be curved in a parabolic shape.

[0039] The first block 322 has a first curved surface 322a. The first curved surface 322a of the first block 322 curves from one side of the surface of the first block 322 that faces (comes into contact with) the film 200 (the bottom surface of the first block 322, i.e., the surface on the negative side in the sixth direction R) to the other side of the surface of the first block 322 that faces the second block 324 (the side surface of the first block 322, i.e., the surface on the negative side in the fifth direction Q). Therefore, compared to a case where the angle between the bottom surface (the surface on the negative side in the sixth direction R) and the side surface (the surface on the negative side in the fifth direction Q) of the first block 322 is, for example, a right angle, a force can be applied to the film 200 uniformly along the curvature between the bottom surface (the surface on the negative side in the sixth direction R) and the side surface (the surface on the negative side in the fifth direction Q) of the first block 322. This prevents a decrease in the break resistance of the portion of the film 200 that comes into contact with the curve between the lower surface (the surface on the negative side of the sixth direction R) and the side surface (the surface on the negative side of the fifth direction Q) of the first block 322.

[0040] The second block 324 has a second curved surface 324a. The second curved surface 324a of the second block 324 curves from one side of the surface of the second block 324 that faces (comes into contact with) the film 200 (the bottom surface of the second block 324, i.e., the surface on the negative side in the sixth direction R) to the other side of the surface of the second block 324 that faces the first block 322 (the side surface of the second block 324, i.e., the surface on the positive side in the fifth direction Q). Therefore, compared to a case where the angle between the bottom surface (the surface on the negative side in the sixth direction R) and the side surface (the surface on the positive side in the fifth direction Q) of the second block 324 is, for example, a right angle, a force can be applied to the film 200 uniformly along the curvature between the bottom surface (the surface on the negative side in the sixth direction R) and the side surface (the surface on the positive side in the fifth direction Q) of the second block 324. This prevents a decrease in the break resistance of the portion of the film 200 that comes into contact with the curve between the lower surface (the surface on the negative side of the sixth direction R) and the side surface (the surface on the positive side of the fifth direction Q) of the second block 324.

[0041] In this embodiment, both the first curved surface 322a and the second curved surface 324a are provided. However, only one of the first curved surface 322a and the second curved surface 324a may be provided. Alternatively, the first curved surface 322a and the second curved surface 324a may not be provided.

[0042] In the present embodiment, while the first accommodating section 210 is being formed in the film 200, the film 200 is not pressed from the opposite side of the first block 322 (the lower side of the first block 322, i.e., the negative side of the first block 322 in the sixth direction R). In other words, while the first accommodating section 210 is being formed in the film 200, the film 200 is not in contact with the surface of the first mold 310 that faces the first block 322. However, when the first accommodating section 210 is being formed in the film 200, the film 200 may be pressed from the opposite side of the first block 322 (the lower side of the first block 322, i.e., the negative side of the first block 322 in the sixth direction R). For example, when the first accommodating section 210 is being formed in the film 200, the film 200 may be in contact with the surface of the first mold 310 that faces the first block 322. The same applies to the formation of the second accommodating section 220.

[0043] The manufacturing method (processing method) of the film 200 is not limited to the example described using Figures 5 to 7. For example, the first storage section 210 and the second storage section 220 may be formed by placing the first mold 310 above the film 200, placing the second mold 320 below the film 200, and pressing the first block 322 and the second block 324 toward the first mold 310 from below to above the film 200. Alternatively, the first storage section 210 and the second storage section 220 may be formed by moving the first mold 310 relative to the second mold 320 (the first block 322 and the second block 324) without moving the second mold 320 (the first block 322 and the second block 324) relative to the first mold 310.

[0044] FIG. 8 is a diagram for explaining an example of a method for wrapping the battery element 100 with the film 200 manufactured (processed) by the apparatus 300 shown in FIGS. 5 to 7 (that is, a method for manufacturing the battery 10).

[0045] The second direction Y and the third direction Z in FIG. 8 are the same as the second direction Y and the third direction Z in FIGS. 1 to 4, respectively.

[0046] As shown in FIG. 8 , the film 200 is folded back from one side of the first housing portion 210 to the other side of the second housing portion 220. As a result, one side of the battery element 100 (the positive side in the third direction Z) is covered by the first housing portion 210 of the film 200, and the other side of the battery element 100 opposite to the one side (the negative side in the third direction Z) is covered by the second housing portion 220 of the film 200. At this time, the recess 232 formed by the method described with reference to FIGS. 5 to 7 remains on the right side (the positive side in the second direction Y) of the battery element 100. Next, the portion of the film 200 overlapping in the third direction Z and the other portion of the film 200 are bonded to each other by welding, for example, except for the portion overlapping the first lead 112 or the second lead 122 in the region surrounding the battery element 100 as viewed from the third direction Z. In this manner, the battery 10 is manufactured. [Example]

[0047] (Example) The film 200 was processed by the method described with reference to Figures 5 to 7. The conditions for the film 200 were as follows. Length in the fourth direction P: 30 cm Width in the fifth direction Q: 40 cm Thickness in the sixth direction R: 0.15 mm Material: Aluminum laminate film The conditions for the device 300 were as follows: Length of each of the first opening 312 and the second opening 314 in the fourth direction P: 25 cm Width of each of the first opening 312 and the second opening 314 in the fifth direction Q: 10 cm Width of the protrusion 316 in the fifth direction Q: 0.4 cm Curvature of the tip (top end) of the protrusion 316: an arc with a curvature radius of 0.2 cm Length of each of the first block 322 and the second block 324 in the fourth direction P: 24.8 cm Width of each of the first block 322 and the second block 324 in the fifth direction Q: 9.8 cm

[0048] (Comparative Example) FIG. 9 is a diagram illustrating a manufacturing (processing) method for film 200 according to a comparative example, and corresponds to FIG. 7 of the embodiment. The fifth direction Q and sixth direction R in FIG. 9 are the same as the fifth direction Q and sixth direction R in FIGS. 5 to 7, respectively. The comparative example is similar to the example, except that while film 200 is pulled along the curvature of the tip (upper end) of protrusion 316 (the end on the positive side in sixth direction R), stopper 400 applies pressure to film 200 from the opposite side of protrusion 316 (the upper side of protrusion 316, i.e., the positive side of protrusion 316 in sixth direction R).

[0049] Fig. 10 is a diagram for explaining the positions at which the thickness of the film 200 was measured. The fourth direction P and the fifth direction Q in Fig. 10 are the same as the fourth direction P and the fifth direction Q in Figs. 5 to 7, respectively.

[0050] The thickness (thickness in the sixth direction R) of the film 200 manufactured (processed) in the examples and comparative examples was measured at six positions, from position 1 to position 6 indicated by black circles in FIG. 10 . Positions 1 to 6 are located at the center in the fifth direction Q of the region between the first storage section 210 and the second storage section 220 (i.e., the center in the fifth direction Q of the region in which the recess 232 is formed). Position 1 is shifted by a distance d (2 cm) from the side of the first storage section 210 and the second storage section 220 on the negative side in the fourth direction P toward the positive direction of the fourth direction P. Positions 1 to 6 are arranged in this order at equal intervals g (1 cm) from the negative to positive direction of the fourth direction P.

[0051] Table 1 shows a summary of the thickness measurements at positions 1 to 6 (FIG. 10) of the film 200 produced (processed) in each of the examples and comparative examples.

[0052] In Table 1, the "Example" row and the "R (%)" column indicate the ratio R of the thickness of the film 200 after processing to the thickness of the film 200 before processing at each of positions 1 to 6 ( FIG. 10 ) of the film 200 manufactured (processed) in the example. The "Example" row and the "Standard Deviation" column indicate the standard deviation of the ratio R at positions 1 to 6 in the example. The "Example" row and the "Average" column indicate the average of the ratio R at positions 1 to 6 in the example. The "Example" row and the "Standard Deviation / Average" column indicate the ratio of the standard deviation to the average of the ratio R at positions 1 to 6 in the example (coefficient of variation).

[0053] In Table 1, the row "Comparative Example" and the column "R (%)" indicate the ratio R of the thickness of the film 200 after processing to the thickness of the film 200 before processing at each of positions 1 to 6 ( FIG. 10 ) of the film 200 manufactured (processed) in the comparative example. Note that at position 1 in the comparative example, the film 200 was broken, and the ratio R could not be measured. The row "Comparative Example" and the column "Standard Deviation" indicate the standard deviation of the ratio R at positions 2 to 6 in the comparative example. The row "Comparative Example" and the column "Average" indicate the average of the ratio R at positions 2 to 6 in the comparative example. The row "Comparative Example" and the column "Standard Deviation / Average" indicate the ratio (coefficient of variation) of the standard deviation to the average of the ratio R at positions 2 to 6 in the comparative example.

[0054] [Table 1]

[0055] From the results of each of the examples and comparative examples in Table 1, it can be said that film 200 can have high resistance to breakage if film 200 is not pressed by stopper 400 from the opposite side of protrusion 316 (the upper side of protrusion 316, i.e., the positive side of protrusion 316 in the sixth direction R) while film 200 is pulled along the curvature of the tip (upper end) of protrusion 316 (the end on the positive side of sixth direction R).

[0056] 10 are located in a range from an end of the battery element 100 in the first direction X to approximately ¼ of the total length of the battery element 100 in the first direction X when viewed from the right side of the battery 10 (the positive side of the second direction Y) when the film 200 wraps around the battery element 100. Therefore, in this embodiment, it can be said that the ratio of the standard deviation to the average thickness of the portion of the film 200 where the recesses 232 are provided can be 0.0500 or less, for example, 0.0250 or less or 0.0100 or less, in a range from the end of the battery element 100 in the first direction X to ¼ of the total length of the battery element 100 in the first direction X.

[0057] Although the embodiments and examples of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above can also be adopted. Below, examples of reference forms are given. 1. A battery element having a positive electrode, a negative electrode, and a separator; a film having a first housing portion covering one side of the battery element and a second housing portion covering the other side of the battery element opposite to the one side; Preparation, A battery, wherein a portion of the film that is folded from one side of the first storage section to the other side of the second storage section has a recess that is recessed toward the battery element and extends along a direction perpendicular to the direction from one side of the battery element to the other side. 2. In the battery described in 1., The recess is curved convexly toward the battery element. 3. The battery according to 1. or 2., A battery, wherein the ratio of the standard deviation to the average thickness of the portion of the film where the recess is provided is 0.0500 or less in a range from an end of the battery element in the one direction to 1 / 4 of the total length of the battery element in the one direction. 4. The battery according to any one of 1. to 3., A battery, wherein the depth of the recess decreases with increasing distance from the center of the battery element in the one direction. 5. A method for manufacturing a film, comprising the steps of: placing a film between a first mold having a first opening and a second opening; and a second mold having a first block and a second block; inserting the first block of the second mold into the first opening of the first mold to form a first storage section in the film; and inserting the second block of the second mold into the second opening of the first mold to form a second storage section in the film; the first mold is located between the first opening and the second opening and has a protruding portion whose tip is curved convexly toward the tip, A method for manufacturing a film, wherein the step of forming the first storage section and the second storage section includes a step of contacting the film with the tip of the protrusion of the first mold without applying pressure to the film from the opposite side of the protrusion of the first mold. 6. In the method for producing a film according to 5., a first curved surface that curves from one surface of the first block facing the film to the other surface of the first block facing the second block; 7. In the method for producing a film according to 6., a second block having a second curved surface that curves from one surface of the second block facing the film to the other surface of the second block facing the first block. 8. A method for producing a film according to any one of 5. to 7.; a step of folding the film from one of the first housing portion and the second housing portion to the other, so that one side of a battery element having a positive electrode, a negative electrode, and a separator is covered with the first housing portion of the film, and the other side of the battery element opposite to the one side is covered with the second housing portion of the film; A method for manufacturing a battery comprising: [Explanation of symbols]

[0058] 10 batteries 100 Battery Elements 110 Positive electrode 112 First Lead 120 negative electrode 122 Second Lead 130 Separator 200 films 210 First storage unit 220 Second Storage Unit 232 recess 300 equipment 310 Type 1 312 First Opening 314 Second Opening 316 Protrusion 320 Type 2 322 Block 1 322a First curved surface 324 Block 2 324a Second curved surface 330 Block 3 400 stopper

Claims

1. a battery element having a positive electrode, a negative electrode, and a separator; a film having a first housing portion covering one side of the battery element and a second housing portion covering the other side of the battery element opposite to the one side; Preparation, a portion of the film that is folded back from one of the first housing section and the second housing section to the other is provided with a recess that extends along a direction perpendicular to a direction from the one side of the battery element toward the other side, and that is recessed toward the battery element in a cross-sectional view perpendicular to the one direction; A battery, wherein when the recess is projected onto the battery element, the recess extends continuously over substantially the entire length of the battery element in the one direction.

2. 10. The battery of claim 1, The recess is curved convexly toward the battery element.

3. 3. The battery according to claim 1, a ratio of the standard deviation of the thickness of the portion of the film where the recess is provided to the average in a range from an end of the battery element in the one direction to 1 / 4 of the total length of the battery element in the one direction is 0.0500 or less.

4. 4. The battery according to claim 1, A battery, wherein the depth of the recess decreases with increasing distance from the center of the battery element in the one direction.

Images