battery cell

Abstract

Ensure the strength of the battery cell in the longitudinal direction. [Solution] The battery cell 10 comprises a battery element 100, a front cover material 210 that covers the longitudinal end of the battery element 100, an outer film 300 in which at least a portion is wrapped around the longitudinal direction of the battery element 100, and a reinforcing body provided along the longitudinal direction of the battery element 100.

Description

Technical Field

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

Background Art

[0002] In recent years, various structures of battery cells such as lithium-ion secondary battery cells have been developed. For example, the battery cell described in Patent Document 1 includes a battery element, two lid materials, and an exterior film. The two lid materials cover both end portions in the longitudinal direction of the battery element. The exterior film is wound around the battery element in the longitudinal direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A certain strength may be required in the longitudinal direction of the battery cell. However, for example, in the battery cell described in Patent Document 1, it may be difficult to ensure the strength in the longitudinal direction of the battery cell with the battery element alone.

[0005] An example of the object of the present invention is to ensure the strength in the longitudinal direction of the battery cell. Other objects of the present invention will become apparent from the description herein.

Means for Solving the Problems

[0006] One aspect of the present invention is as follows. [1] A battery element, A lid material that covers an end portion in the longitudinal direction of the battery element, An exterior film at least a part of which is wound around the battery element in the longitudinal direction, A reinforcing body provided along the longitudinal direction of the battery element, A battery cell equipped with the following features. [2] The battery cell according to [1], wherein one end of the reinforcing member in the longitudinal direction is joined to the cover material. [3] The battery cell according to [1] or [2], wherein at least a portion of the reinforcing body has multiple folded and pulled-out portions of the outer film. [Effects of the Invention]

[0007] According to the above embodiment of the present invention, the longitudinal strength of the battery cell can be ensured. [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] This figure shows a modified battery cell. [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 magnified front 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. 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, an outer film 300, and a reinforcing plate 400. The outer film 300 has a winding portion 302 and an unwinding portion 304.

[0014] The battery element 100 has a roughly rectangular parallelepiped shape. The longitudinal direction of the battery element 100 is roughly parallel to the X direction. The length of the battery element 100 in the X direction is not limited to the following, but for example, 300 mm or more and 500 mm or less, preferably 450 mm or less. The short direction of the battery element 100 is roughly parallel to the Z direction. The length of the battery element 100 in the Z direction is not limited to the following, but 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 roughly parallel to the Y direction. The thickness of the battery element 100 in the Y direction is not limited to the following, but 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 has 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 adjacent positive and negative electrodes in the Y direction. For example, each of a plurality of sheet-like separators may be located between the adjacent positive and negative electrodes in the Y direction. Alternatively, when viewed from the X direction, the separator may have a zigzag shape with folds on both sides in the Z direction. In this example, the portion located between the folds on both sides of the separator in the Z direction is disposed between the adjacent positive and negative electrodes 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 with both sides of one of the positive electrode and the negative electrode covered by the separator. In another example, a laminate including a plurality of unit laminates 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] As shown in FIG. 3, the positive electrode tab 110 is disposed in front of the battery element 100. The positive electrode tab 110 is electrically connected to the positive electrode current collector 102a. The positive electrode current collector 102a is drawn forward from the positive electrode 102. Thereby, the positive electrode tab 110 is electrically connected to the plurality of positive electrodes 102.

[0017] As shown in FIG. 3, the negative electrode tab 120 is disposed behind the battery element 100. The negative electrode tab 120 is electrically connected to the negative electrode current collector 104a. The negative electrode current collector 104a is drawn backward from the negative electrode 104. Thereby, the negative electrode tab 120 is electrically connected to the plurality of negative electrodes 104.

[0018] The front cover member 210 covers the front end portion of the battery element 100. The front cover member 210 is made of, for example, resin, metal, or the like. The front end portion of the positive electrode tab 110 protrudes from the 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, the longitudinal direction of the front cover member 210 is substantially parallel to the Z direction, and the short-side direction of the front cover member 210 is substantially parallel to the Y direction.

[0019] The rear cover member 220 covers the rear end portion of the battery element 100. The rear cover member 220 is made of, for example, resin, metal, or the like. The rear end portion of the negative electrode tab 120 protrudes from the 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, the longitudinal direction of the rear cover member 220 is substantially parallel to the Z direction, and the short-side direction of the rear cover member 220 is substantially parallel to the Y direction.

[0020] As shown in FIGS. 1 and 2, the winding portion 302 has a substantially cylindrical shape that opens toward both the front and the rear. The front cover member 210 is disposed inside the front opening of the winding portion 302. The rear cover member 220 is disposed inside the rear opening of the winding portion 302. The winding portion 302 is wound around the battery element 100, the front cover member 210, and the rear cover member 220 once in the circumferential direction about the X axis. Thereby, the front cover member 210, the rear cover member 220, and the winding portion 302 form a housing space 500 for housing the battery element 100. An electrolytic solution (not shown) is housed in the housing space 500 together with the battery element 100. Note that the winding mode of the winding portion 302 around the battery element 100 is not limited to the above-described example.

[0021] The outer peripheral surface of the front cover member 210 around the X axis and the inner peripheral surface of the front opening of the winding portion 302 around the X axis are joined to each other, for example, by heat fusion. Thereby, the front sealing portion 510 is formed.

[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 to 3, the reinforcing plate 400 is positioned above the pull-out portion 304. The reinforcing plate 400 is provided along the longitudinal direction of the upper surface of the battery element 100. This allows the reinforcing plate 400 to function as a reinforcement that strengthens the battery element 100 in the X direction. Therefore, in this embodiment, the longitudinal strength of the battery cell 10 can be ensured compared to the case where the reinforcing plate 400 is not provided. Note that the position where the reinforcing plate 400 is provided is not limited to the examples shown in Figures 1 to 3. For example, the reinforcing plate 400 may be provided along at least a portion of the lower surface, left side, and right side of the battery element 100.

[0025] The front end of the reinforcing plate 400 is joined to the front cover material 210, for example, by laser welding. The rear end of the reinforcing plate 400 is joined to the rear cover material 220, for example, by laser welding. The rigidity of each of the front cover material 210, the rear cover material 220, and the reinforcing plate 400 can be made higher than the rigidity of the battery element 100. Therefore, in this embodiment, the strength of the battery element 100 can be reinforced from at least three directions by the front cover material 210, the rear cover material 220, and the reinforcing plate 400.

[0026] The reinforcing plate 400 does not have to be joined to the front cover material 210 and the rear cover material 220. Alternatively, the reinforcing plate 400 may be joined to only one of the front cover material 210 and the rear cover material 220.

[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 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.

[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 drawer portion 304 is bent along the top surface of the battery element 100.

[0035] Next, the reinforcing plate 400 is attached above the drawer section 304.

[0036] In this way, the battery cell 10 is manufactured.

[0037] Figure 4 shows a modified battery cell 10A. The modified battery cell 10A is the same as the battery cell 10 according to the embodiment, except for the following points.

[0038] The outer film 300A of the modified battery cell 10A has a winding portion 302A and an extension portion 304A. The winding portion 302A of the modified example is wound once around the battery element 100, the front cover material 210 and the rear cover material 220 in the X direction, similar to the winding portion 302 of the embodiment. The extension portion 304A of the modified example is extended from the winding portion 302A, similar to the extension portion 304 of the embodiment.

[0039] In the example shown in Figure 4, the extension portion 304A is bent twice when viewed from the X direction. Specifically, when viewed from the X direction, the base end of the extension portion 304A is bent from above to the right near the upper left corner of the front cover material 210. Also, when viewed from the X direction, the approximate center of the extension portion 304A is bent from right to left above the front cover material 210. Therefore, the rigidity of the extension portion 304A in the X direction can be improved compared to the case where the extension portion 304A is simply extended. As a result, the extension portion 304A can function as a reinforcing body that reinforces the strength of the battery element 100 in the X direction. Therefore, in the modified example, the longitudinal strength of the battery cell 10A can be ensured compared to the case where the extension portion 304A is simply extended.

[0040] In the example shown in Figure 4, when viewed from the X direction, the tip of the lead portion 304A is folded inward toward the inside of the lead portion 304A. This prevents the tip of the lead portion 304A from being exposed toward the outside of the lead portion 304A. For example, the lead portion 304A may have a conductor such as a conductive sheet. This conductor may be exposed from the tip of the lead portion 304A. In the example shown in Figure 4, the conductor exposed from the tip of the lead portion 304A can be prevented from being exposed toward the outside of the lead portion 304A. Therefore, a short circuit of the outer film 300A via the conductor can be suppressed.

[0041] The manner in which the pull-out portion 304A is folded is not limited to the example shown in Figure 4. For example, when viewed from the X direction, the pull-out portion 304A may be folded three or more times. That is, when viewed from the X direction, the pull-out portion 304A can be folded multiple times.

[0042] In the modified example, a reinforcing plate 400 may be further provided, similar to the embodiment. In this case, both the pull-out portion 304A and the reinforcing plate 400 can function as reinforcing bodies that reinforce the strength of the battery element 100 in the X direction.

[0043] 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.

[0044] For example, in this embodiment, the reinforcing plate 400 is provided on the outside of the outer film 300. However, the reinforcing plate 400 may also be provided on the inside of the outer film 300.

[0045] 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 of the front or rear sides of the battery element 100 in the X direction. 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 from which the positive electrode tab 110 and the negative electrode tab 120 of the battery element 100 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]

[0046] 10,10A battery cell 100 battery elements 102 Positive electrode 102a Positive electrode current collector 104 Negative electrode 104a Negative electrode current collector 110 Positive Tab 120 Negative Electrode Tabs 210 Front lid material 220 Rear lid material 300, 300A Exterior Film 302,302A Wrapping part 304,304A Drawer part 304a 1st drawer part 304b 2nd drawer part 400 Reinforcement Plate 500 storage space 510 Front sealing section 520 Rear sealing part 530 Side sealing part

Claims

1. Battery elements, Two cover materials that cover both ends in the longitudinal direction of the aforementioned battery element, An outer film, at least a portion of which is wrapped around the longitudinal direction of the battery element, A reinforcing body provided along the longitudinal direction of the battery element, with both ends in the longitudinal direction joined to the two cover materials, A battery cell equipped with the following features.

2. The battery cell according to claim 1, wherein the reinforcing member is located only on one side of the battery element in the short direction perpendicular to the longitudinal direction.

3. The battery cell according to claim 1 or 2, wherein the reinforcing member is located on the upper surface side of the battery element.

4. The battery cell according to claim 1 or 2, wherein the strength of the battery element is reinforced from at least three directions by the two cover materials and the reinforcing body.

5. The battery cell according to claim 1 or 2, wherein the reinforcing member is in the shape of a plate. cell.

6. The two lid materials and the outer film form a housing space for housing the battery element. The battery cell according to claim 1 or 2, wherein the reinforcing member is located outside the housing space.

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