Battery cell manufacturing method

Abstract

To suppress exposure of an end of an exterior film.SOLUTION: The battery cell 10 includes a battery element 100, a positive electrode tab 110 electrically connected to the battery element 100, a front lid member 210 that covers an end portion of the battery element 100 and from which the positive electrode tab 110 is drawn out, and an exterior film 300 at least partially wound around the battery element 100. At least a part of the front lid member 210 covers at least a part of the end portion of the exterior film 300.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a battery cell.

Background Art

[0002] In recent years, various structures for battery cells such as lithium ion secondary battery cells have been developed. For example, the battery cells described in Patent Documents 1 and 2 include a battery element, two lid members, and an exterior film. The two lid members cover both longitudinal ends of the battery element. The exterior film is wound around the longitudinal direction of the battery element.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] For example, in the battery cell described in Patent Document 1, when the exterior film is wound around the lid member, an end portion of the exterior film is exposed. When the end portion of the exterior film is exposed, it may become difficult to suppress short-circuiting of the exterior film via a conductor such as a conductive sheet included in the exterior film.

[0005] An example of the object of the present invention is to suppress exposure of an end portion of an exterior film. Other objects of the present invention will become apparent from the description of the present specification.

Means for Solving the Problem

[0006] One aspect of the present invention is as follows. [1] a battery element, a tab electrically connected to the battery element, a lid member that covers an end of the battery element and from which the tab is drawn out, An outer film, at least a portion of which is wrapped around the battery element, Equipped with, A battery cell in which at least a portion of the cover material covers at least a portion of the edge of the outer film. [2] The battery cell according to [1], wherein at least a portion of the cover material covers at least a portion of the outer surface of the outer film. [3] The battery cell according to [1] or [2], further comprising another cover material that covers the other end of the battery element opposite to the end of the battery element. [Effects of the Invention]

[0007] According to the above embodiment of the present invention, the exposure of the edges of the outer film can be suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This is a front perspective view of a battery cell according to the embodiment. [Figure 2] This is a front-extended, magnified perspective view of a portion of a battery cell according to the embodiment. [Figure 3] This is a right side view of a battery cell according to an embodiment. [Figure 4] Figure 2 is a schematic diagram of the AA section. [Figure 5] This figure shows a modified example of Figure 4. [Modes for carrying out the invention]

[0009] Embodiments and modified examples of the present invention will be described below with reference to the drawings. In all drawings, similar components are denoted by the same reference numerals, and their descriptions are omitted where appropriate.

[0010] Figure 1 is a front perspective view of the battery cell 10 according to the embodiment. Figure 2 is a front enlarged perspective view of a portion of the battery cell 10 according to the embodiment. Figure 3 is a right side view of the battery cell 10 according to the embodiment. Figure 4 is a schematic cross-sectional view of AA in Figure 2. In Figure 3, the outer film 300 is shown transparently for illustrative purposes.

[0011] Each figure is labeled with X, Y, and Z directions for explanatory purposes. The X direction indicates the front-to-back direction of the battery cell 10. The Y direction is perpendicular to the X direction. The Y direction indicates the left-to-right direction of the battery cell 10. The Z direction is perpendicular to both the X and Y directions. The Z direction indicates the up-to-down direction of the battery cell 10. The directions indicated by the arrows indicating the X direction, the Y direction, and the Z direction are the rear, left, and up directions, respectively. However, the relationships between the X, Y, Z, front-to-back, left-to-right, and up-to-down directions of the battery cell 10 are not limited to this example.

[0012] The white circles with an "X" indicating the X, Y, or Z direction indicate that the direction from the front to the back of the page is the direction indicated by the corresponding arrow.

[0013] The battery cell 10 comprises a battery element 100, a positive electrode tab 110, a negative electrode tab 120, a front cover material 210, a rear cover material 220, and an outer film 300. The outer film 300 has a winding portion 302 and an unwinding portion 304.

[0014] The battery element 100 has a substantially rectangular parallelepiped shape. The longitudinal direction of the battery element 100 is substantially parallel to the X direction. The length of the battery element 100 in the X direction is, but not limited to, for example, 300 mm or more and 500 mm or less, preferably 450 mm or less. The width direction of the battery element 100 is substantially parallel to the Z direction. The length of the battery element 100 in the Z direction is, but not limited to, for example, 90 mm or more and 130 mm or less, preferably 120 mm or less. The thickness direction of the battery element 100 is substantially parallel to the Y direction. The thickness of the battery element 100 in the Y direction is, but not limited to, for example, 20 mm or more and 50 mm or less, preferably 45 mm or less. However, the shape of the battery element 100 is not limited to this example.

[0015] The battery element 100 includes at least one positive electrode not shown, at least one negative electrode not shown, and at least one separator not shown. For example, a plurality of positive electrodes and a plurality of negative electrodes are alternately stacked in the Y direction. At least a part of the separator is located between the positive electrode and the negative electrode adjacent to each other in the Y direction. For example, each of the plurality of sheet-shaped separators may be located between a positive electrode and a negative electrode adjacent to each other in the Y direction. Alternatively, one sheet-shaped separator may be formed in a zigzag-folded shape passing through a region between a positive electrode and a negative electrode adjacent to each other in the Y direction. Alternatively, the positive electrode, the negative electrode, and the separator may be wound such that the separator is disposed between the positive electrode and the negative electrode. In one example, the positive electrode, the negative electrode, and the separator are wound in a state where both surfaces of one of the positive electrode and the negative electrode are covered with the separator. In another example, a stacked body including a plurality of unit stacked bodies each including a positive electrode, a separator, and a negative electrode in this order may be wound. However, the winding structure of the positive electrode, the negative electrode, and the separator is not limited to these examples.

[0016] The positive electrode tab 110 is disposed in front of the battery element 100. A rear end portion of the positive electrode tab 110 is electrically connected to a positive electrode current collector 102a. The positive electrode current collector 102a is drawn forward from the positive electrode of the battery element 100. Thereby, the positive electrode tab 110 is electrically connected to the positive electrode of the battery element 100.

[0017] The negative electrode tab 120 is disposed behind the battery element 100. A front end portion of the negative electrode tab 120 is electrically connected to a negative electrode current collector 104a. The negative electrode current collector 104a is drawn rearward from the negative electrode of the battery element 100. Accordingly, the negative electrode tab 120 is electrically connected to the negative electrode of the battery element 100.

[0018] A front cover member 210 covers a front end portion of the battery element 100. The front cover member 210 is made of, for example, resin, metal, or the like. A front end portion of the positive electrode tab 110 is drawn out from a front surface of the front cover member 210. When viewed from the front, the front cover member 210 has a substantially rectangular shape. When viewed from the front, a longitudinal direction of the front cover member 210 is substantially parallel to the Z direction, and a lateral direction of the front cover member 210 is substantially parallel to the Y direction.

[0019] A rear cover member 220 covers a rear end portion of the battery element 100. The rear cover member 220 is made of, for example, resin, metal, or the like. A rear end portion of the negative electrode tab 120 is drawn out from a rear surface of the rear cover member 220. When viewed from the rear, the rear cover member 220 has a substantially rectangular shape. When viewed from the rear, a longitudinal direction of the rear cover member 220 is substantially parallel to the Z direction, and a lateral direction of the rear cover member 220 is substantially parallel to the Y direction.

[0020] As shown in Figures 1 and 2, a wound portion 302 has a substantially cylindrical shape opened toward both the front and the rear. Inside the front opening of the wound portion 302, the front cover member 210 is disposed, excluding a front convex portion 212 described later. Inside the rear opening of the wound portion 302, the rear cover member 220 is disposed, excluding a rear convex portion 222 described later. The wound portion 302 is wound one turn around the battery element 100, the front cover member 210 and the rear cover member 220 in the X direction. Accordingly, the front cover member 210, the rear cover member 220 and the wound portion 302 form an accommodation space 500 that accommodates the battery element 100. In the accommodation space 500, an electrolytic solution (not shown) is accommodated together with the battery element 100. Note that the winding mode of the wound portion 302 around the battery element 100 is not limited to the example described above.

[0021] The outer circumferential surface of the front cover material 210 around the X direction and the inner circumferential surface of the front opening of the winding portion 302 around the X direction are joined to each other, for example, by heat fusion. This forms the front sealing portion 510.

[0022] The outer circumferential surface of the rear cover material 220 around the X direction and the inner circumferential surface of the rear opening of the winding portion 302 around the X direction are joined to each other, for example, by heat fusion. This forms the rear sealing portion 520.

[0023] As shown in Figures 1 and 2, viewed from the front, the extension portion 304 extends from the upper left corner of the battery element 100 of the winding portion 302. Specifically, as shown in Figure 2, the extension portion 304 includes a first extension portion 304a and a second extension portion 304b. The first extension portion 304a extends from one of the circumferential ends of the winding portion 302 around the X direction. The second extension portion 304b extends from the other of the circumferential ends of the winding portion 302 around the X direction. The first extension portion 304a and the second extension portion 304b are joined to each other, for example, by heat fusion. This forms a lateral sealing portion 530 when viewed from the front. The extension portion 304 is bent along the upper surface of the battery element 100. However, the extension portion 304 does not have to be bent. Also, the shape of the bend of the extension portion 304 is not limited to the shape according to this embodiment.

[0024] As shown in Figures 1, 2, and 4, a forward projection 212 is provided on the outer circumferential surface of the front cover material 210. The forward projection 212 is provided around the entire circumference of the outer circumferential surface of the front cover material 210. However, the forward projection 212 may be provided only on a portion of the entire circumference of the outer circumferential surface of the front cover material 210. The forward projection 212 is located in front of the front end of the outer film 300. As a result, the forward projection 212 covers the front end of the outer film 300. Therefore, exposure of the front end of the outer film 300 can be suppressed by the forward projection 212. Consequently, even if a conductor such as a conductive sheet contained in the outer film 300 is exposed from the front end of the outer film 300, a short circuit of the outer film 300 via the conductor can be suppressed.

[0025] As shown in Figure 1, the outer circumferential surface of the rear cover material 220 is provided with a rear projection 222, similar to the outer circumferential surface of the front cover material 210. The rear projection 222 covers the rear end of the outer film 300, similar to the front projection 212. Therefore, the exposure of the rear end of the outer film 300 can be suppressed by the rear projection 222. Consequently, even if a conductor such as a conductive sheet contained in the outer film 300 is exposed from the rear end of the outer film 300, a short circuit of the outer film 300 via the conductor can be suppressed.

[0026] In this embodiment, both a forward projection 212 and a rear projection 222 are provided. However, only one of the forward projection 212 or the rear projection 222 may be provided.

[0027] Next, an example of a method for manufacturing the battery cell 10 according to the embodiment will be described. In this example, the battery cell 10 according to the embodiment is manufactured as follows.

[0028] First, the battery element 100 is manufactured. The battery element 100 has at least one positive electrode, at least one negative electrode, and at least one separator.

[0029] Next, the positive electrode tab 110 and the front cover material 210 are joined together. Similarly, the negative electrode tab 120 and the rear cover material 220 are joined together. Next, the positive electrode tab 110 and the positive electrode current collector 102a are joined together. Similarly, the negative electrode tab 120 and the negative electrode current collector 104a are joined together. However, the positive electrode tab 110 and the positive electrode current collector 102a may be joined together first, and then the positive electrode tab 110 and the front cover material 210 may be joined together. Similarly, the negative electrode tab 120 and the negative electrode current collector 104a may be joined together first, and then the negative electrode tab 120 and the rear cover material 220 may be joined together.

[0030] Next, the outer film 300 is wrapped around the battery element 100, the front cover material 210, and the rear cover material 220 in the X direction. This forms the wrapped portion 302. The excess length of the outer film 300 is then pulled out as the pull-out portion 304. In this state, the front projection 212 is located in front of the front end of the outer film 300. As a result, the front end of the outer film 300 is covered by the front projection 212. Also, the rear projection 222 is located behind the rear end of the outer film 300. As a result, the rear end of the outer film 300 is covered by the rear projection 222.

[0031] Next, the outer circumferential surface of the front cover material 210 around the X direction and the inner circumferential surface of the front opening of the winding portion 302 around the X direction are joined to each other by heat fusion. This forms the front sealing portion 510. Next, the outer circumferential surface of the rear cover material 220 around the X direction and the inner circumferential surface of the rear opening of the winding portion 302 around the X direction are joined to each other by heat fusion. This forms the rear sealing portion 520.

[0032] Next, electrolyte is injected into the containment space 500 through the gap between the first extraction portion 304a and the second extraction portion 304b. Then, the containment space 500 is evacuated through the gap between the first extraction portion 304a and the second extraction portion 304b. Next, the first extraction portion 304a and the second extraction portion 304b are joined by heat fusion to form a lateral sealing portion 530. This vacuum seals the containment space 500.

[0033] The method for vacuum sealing the containment space 500 is not limited to the example described above. In other examples, first, the first draw-out portion 304a and the second draw-out portion 304b are joined by heat fusion to form a lateral sealing portion 530. Next, electrolyte is injected into the containment space 500 through an injection hole provided in at least one of the front cover material 210 and the rear cover material 220. Then, the containment space 500 is vacuumed through the injection hole. Finally, the injection hole is sealed with a predetermined cover material.

[0034] Next, the lateral sealing portion 530 is bent along the upper surface of the battery element 100.

[0035] In this way, the battery cell 10 is manufactured.

[0036] Figure 5 shows a modified example of Figure 4.

[0037] The front cover material 210A of the modified battery cell 10A has a front covering portion 212A. The front covering portion 212A covers the front end of the outer film 300 and the area near the front end of the outer peripheral surface of the outer film 300. In particular, above the housing space 500 and near the front end of the outer film 300, the front covering portion 212A covers the upper surface of the lateral sealing portion 530. When the front covering portion 212A covers at least a portion of the front end of the outer film 300, even if a conductor such as a conductive sheet contained in the outer film 300 is exposed from the front end of the outer film 300, a short circuit of the outer film 300 via the conductor can be suppressed. When the front covering portion 212A covers at least a portion of the outer peripheral surface of the outer film 300, the position of the front end of the outer film 300 can be fixed by the front covering portion 212A.

[0038] In one example, the front covering portion 212A can be formed by deforming the front protrusion 212 according to the embodiment. For example, after completing all steps of the manufacturing method of the battery cell 10 according to the embodiment, the material constituting the front protrusion 212 is made to flow backward by crushing the front protrusion 212 while applying heat to it. As a result, the material constituting the front protrusion 212 covers not only the front end of the outer film 300 but also the outer circumferential surface of the outer film 300. In particular, if the lateral sealing portion 530 is bent along the battery element 100 before the front protrusion 212 is deformed, the outer surface of the lateral sealing portion 530 can be covered by the front covering portion 212A.

[0039] The structure of the front cover 210A is described in the example shown in Figure 5. The structure of the front cover 210A in Figure 5 can be similarly applied to the rear cover.

[0040] The embodiments and modifications of the present invention have been described above with reference to the drawings, but these are merely examples of the present invention, and various other configurations can also be adopted.

[0041] For example, in this embodiment, the positive electrode tab 110 and the negative electrode tab 120 are located on opposite sides of the battery element 100 in the X direction. However, both the positive electrode tab 110 and the negative electrode tab 120 may be located on only one side of the battery element 100 in the X direction, either the front or the rear. In this case, the front and rear ends of the battery element 100 are covered, for example, by two cover materials. Alternatively, only the side of the battery element 100 from which the positive electrode tab 110 and the negative electrode tab 120 are drawn may be covered by the cover material. In this example, the outer film 300 may be sealed and folded along the battery element 100 on the opposite side of the cover material of the battery element 100. [Explanation of Symbols]

[0042] 10,10A battery cell 100 battery elements 102a Positive electrode current collector 104a Negative electrode current collector 110 Positive Tab 120 Negative Electrode Tabs 210,210A Front lid material 212 Forward protrusion 212A Front covering section 220 Rear lid material 222 Rear protrusion 300 Exterior Film 302 Wrapping part 304 Drawer part 304a 1st drawer part 304b 2nd drawer part 500 storage space 510 Front sealing section 520 Rear sealing part 530 Side sealing part

Claims

1. A step of preparing a battery element, a tab electrically connected to the battery element, a cover material that covers the end of the battery element and from which the tab is pulled out and has a protrusion on its outer surface, and an outer film that at least a portion of which is wrapped around the battery element and the cover material and whose end is covered by the protrusion, A step of covering the outer surface of the outer film with a covering portion formed by deforming the protrusion by crushing it while applying heat to the protrusion, A method for manufacturing battery cells, comprising:

2. The method for manufacturing a battery cell according to claim 1, wherein the step of preparing the battery element, the tab, the lid material, and the outer film comprises the step of joining the outer surface of the lid material and the inner surface of the outer film by heat fusion.

3. The step of preparing the battery element, the tab, the lid material, and the outer film includes the step of joining together the pulled-out portions of the outer film that have been pulled out from the wrapped portion of the outer film that has been wrapped around the battery element and the lid material to form a sealing portion. The method for manufacturing a battery cell according to claim 1 or 2, wherein the step of covering the outer peripheral surface of the outer film with the covering portion comprises the step of covering the sealing portion of the outer film with the covering portion.

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