Battery cell

Abstract

To stabilize the characteristics of a battery cell.SOLUTION: A battery cell 10 comprises: a battery element 100; a positive electrode tab 110 electrically connected with the battery element 100 via an aggregation part of a positive electrode current collector 102a led out from the battery element 100; a front lid material 210 that covers one end part of the battery element 100 and from which the positive electrode tab 110 is led out; and an outer package film 300 at least partially wound around the battery element 100. There are wrinkles of the outer package film 300 around the aggregation part of the positive electrode current collector 102a, of the outer package film 300.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] In recent years, various structures of battery cells, such as lithium-ion secondary battery cells, have been developed. For example, a battery cell described in Patent Document 1 includes a battery element, two lid materials, and an exterior film. The two lid materials cover both longitudinal ends of the battery element. A tab electrically connected to the battery element extends from each lid material. The exterior film is wrapped around the battery element in the longitudinal direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-108623 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, in the battery cell described in Patent Document 1, wrinkles may form in the exterior film due to distortion of the exterior film's shape. However, if wrinkles in the exterior film exist around the battery element of the exterior film, the wrinkles may be transferred to the battery element. This may affect the characteristics of the battery cell.

[0005] One example of an object of the present invention is to stabilize the characteristics of a battery cell. Other objects of the present invention will become apparent from the description of this 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 via a current collector aggregate portion drawn out from the battery element; a cover material that covers one end of the battery element and through which the tab is pulled out; an exterior film at least partially wrapped around the battery element; Equipped with a wrinkle in the exterior film is present around the gathering portion of the current collector in the exterior film. [2] The battery cell according to [1], wherein the size of the lid member is larger than the size of the battery element when viewed from the pull-out direction of the tab. [3] The battery cell according to [1], wherein the size of the lid member is smaller than the size of the battery element when viewed from the pull-out direction of the tab. [Effects of the Invention]

[0007] According to the above aspect of the present invention, the characteristics of the battery cell can be stabilized. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a front perspective view of a battery cell according to the embodiment. [Figure 2] FIG. 2 is an enlarged front perspective view of a portion of a battery cell according to an embodiment. [Figure 3] FIG. 2 is a right side view of the battery cell according to the embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view of FIG. 3 taken along the line AA. [Figure 5] 5A to 5C are diagrams illustrating a first example of a method for manufacturing a battery cell according to an embodiment. [Figure 6] 10A and 10B are diagrams illustrating a second example of a method for manufacturing a battery cell according to an embodiment. [Figure 7] FIG. 10 is a front perspective view of a battery cell according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments and modifications 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 descriptions thereof will be omitted as appropriate.

[0010] Fig. 1 is a front perspective view of a battery cell 10 according to an embodiment. Fig. 2 is an enlarged front perspective view of a portion of the battery cell 10 according to an embodiment. Fig. 3 is a right side view of the battery cell 10 according to an embodiment. Fig. 4 is a schematic cross-sectional view taken along line AA in Fig. 3. For the sake of explanation, Fig. 3 shows an exterior film 300 in a see-through state.

[0011] For the sake of explanation, each figure is labeled with an X direction, a Y direction, and a Z direction. The X direction indicates the front-to-rear 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 direction and the Y direction. The Z direction indicates the up-to-down direction of the battery cell 10. The direction indicated by the arrow indicating the X direction, the direction indicated by the arrow indicating the Y direction, and the direction indicated by the arrow indicating the Z direction are the rearward, leftward, and upward directions, respectively. However, the relationships between the X direction, Y direction, Z direction, front-to-rear direction, left-to-right direction, and up-to-down direction of the battery cell 10 are not limited to this example.

[0012] The white circle with an X indicating the X, Y or Z direction indicates that the direction from the front of the paper to the back is the direction indicated by the arrow indicating that direction.

[0013] The battery cell 10 includes a battery element 100, a positive electrode tab 110, a negative electrode tab 120, a front cover member 210, a rear cover member 220, and an exterior film 300. The exterior film 300 has a wound portion 302 and a pulled-out 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 not limited to, but is, for example, 300 mm to 500 mm, and preferably 450 mm or less. The lateral 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 not limited to, but is, for example, 90 mm to 130 mm, and 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 not limited to, but is, for example, 20 mm to 50 mm, and 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, multiple positive electrodes and multiple negative electrodes are alternately stacked in the Y direction. At least a portion of the separator is located between adjacent positive electrodes and negative electrodes in the Y direction. For example, multiple sheet-like separators may each be located between adjacent positive electrodes and negative electrodes in the Y direction. Alternatively, a single sheet-like separator may have a zigzag shape that passes through the region between adjacent positive electrodes and negative electrodes in the Y direction. Alternatively, the positive electrode, negative electrode, and separator may be wound so that the separator is located between the positive electrode and negative electrode. In one example, the positive electrode, negative electrode, and separator are wound with both surfaces of one of the positive electrode and negative electrode covered by the separator. In another example, a stack including multiple unit stacks 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, negative electrode, and 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 rear end of the positive electrode tab 110 is electrically connected to the positive electrode current collector 102a. The positive electrode current collector 102a is pulled forward from the positive electrode 102. This allows the positive electrode tab 110 to be electrically connected to the plurality of positive electrodes 102. As shown in FIG. 4, the plurality of positive electrode current collectors 102a are aggregated between the battery element 100 and the front cover member 210. In other words, a grouping of the plurality of positive electrode current collectors 102a exists between the battery element 100 and the positive electrode tab 110. The width of the grouping of the plurality of positive electrode current collectors 102a in the Y direction narrows as it moves forward from the battery element 100. Note that in FIG. 4, the plurality of positive electrode current collectors 102a pulled out from the battery element 100 and aggregated is schematically illustrated as a triangle.

[0017] As shown in FIG. 3, the negative electrode tab 120 is disposed at the rear of the battery element 100. The front end of the negative electrode tab 120 is electrically connected to the negative electrode current collector 104a. The negative electrode current collector 104a is pulled out rearward from the negative electrode 104. In this way, the negative electrode tab 120 is electrically connected to a plurality of negative electrodes 104. Similar to the example shown in FIG. 4, a gathering portion of a plurality of negative electrode current collectors 104a exists between the battery element 100 and the negative electrode tab 120.

[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 is pulled out toward the front 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 lateral 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 is pulled out rearward 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 lateral direction of the rear cover member 220 is substantially parallel to the Y direction.

[0020] As shown in FIGS. 1 and 2 , the wound portion 302 has a generally cylindrical shape that is open both front and rear. A front cover member 210 is disposed inside the front opening of the wound portion 302. A rear cover member 220 is disposed inside the rear opening of the wound portion 302. The wound portion 302 is wound around the battery element 100, the front cover member 210, and the rear cover member 220 in the X direction by one turn. As a result, the front cover member 210, the rear cover member 220, and the wound portion 302 form a storage space 500 that stores the battery element 100. The storage space 500 stores the battery element 100 as well as an electrolyte (not shown). The manner in which the wound portion 302 wraps around the battery element 100 is not limited to the example described above.

[0021] The outer peripheral surface of the front lid member 210 in the X direction and the inner peripheral surface of the front opening of the wound portion 302 in the X direction are joined to each other by, for example, heat fusion, thereby forming the front sealing portion 510.

[0022] The outer peripheral surface of the rear lid member 220 in the X direction and the inner peripheral surface of the rear opening of the wound portion 302 in the X direction are joined to each other by, for example, heat fusion, thereby forming the rear sealing portion 520.

[0023] As shown in FIGS. 1 and 2 , the pull-out portion 304 is pulled out from the upper left corner of the wound portion 302 of the battery element 100 when viewed from the front. Specifically, as shown in FIG. 2 , the pull-out portion 304 includes a first pull-out portion 304a and a second pull-out portion 304b. The first pull-out portion 304a is pulled out from one of the circumferential ends of the wound portion 302 in the X direction. The second pull-out portion 304b is pulled out from the other of the circumferential ends of the wound portion 302 in the X direction. The first pull-out portion 304a and the second pull-out portion 304b are joined to each other by, for example, heat fusion. This forms a side sealing portion 530 when viewed from the front. The pull-out portion 304 is folded along the top surface of the battery element 100. However, the pull-out portion 304 does not have to be folded. The folding shape of the pull-out portion 304 is not limited to the shape described in the embodiment.

[0024] As shown in Fig. 3, the exterior film 300 has a front portion 310, a rear portion 320, and a central portion 330. The front portion 310 is located around the X-direction periphery of the aggregated portion of the positive electrode current collector 102a. The rear portion 320 is located around the X-direction periphery of the aggregated portion of the negative electrode current collector 104a. The central portion 330 is located between the front portion 310 and the rear portion 320 in the X-direction. The central portion 330 is located around the X-direction periphery of the battery element 100.

[0025] In the exterior film 300, wrinkles are not present in the central portion 330, but are present in at least one of the front portion 310 and the rear portion 320. Wrinkles may form in the exterior film 300 due to distortion of the shape of the exterior film 300. If wrinkles are present in the central portion 330, they may be transferred to the battery element 100. This may affect the characteristics of the battery cell 10. For example, in the wrinkled portion, uneven spacing between the positive and negative electrodes may occur, resulting in variations in ionic resistance. As another example, uneven spacing between the positive and negative electrodes may accelerate deterioration in areas where the resistance between the positive and negative electrodes is relatively low compared to other areas. It may be relatively difficult to remove wrinkles from the exterior film 300. In this embodiment, even if wrinkles are formed in the central portion 330, the wrinkles are transferred to at least one of the front portion 310 and the rear portion 320. Wrinkles present in the front portion 310 or the rear portion 320 are unlikely to affect the characteristics of the battery cell 10. This can stabilize the characteristics of the battery cell 10. Furthermore, in the embodiment, the space formed on the inner surface of the front portion 310 or the rear portion 320 by the wrinkles can be used as a space for storing an electrolyte or a space for storing a gas.

[0026] Wrinkles in the exterior film 300 may occur due to, for example, the difference in size between the battery element 100 and the front cover member 210 or the rear cover member 220 when viewed from the X direction.

[0027] In one example, the size of the front cover member 210 may be larger than the size of the battery element 100 when viewed in the X direction. For example, the length of the front cover member 210 in the Y direction may be longer than the thickness of the battery element 100 in the Y direction. For example, a battery module may be formed by stacking multiple battery cells 10 in the Y direction. In this example, a compression pad may be disposed between the central portions 330 of adjacent battery cells 10 in the Y direction. In this battery module, the length of the front cover member 210 in the Y direction may be longer than the thickness of the battery element 100 in the Y direction by an amount equivalent to the thickness of the compression pad in the Y direction. This allows multiple battery cells 10 to be stably stacked in the Y direction. As in the above example, the size of the rear cover member 220 may be larger than the size of the battery element 100 when viewed in the X direction.

[0028] In another example, the size of the front cover member 210 may be smaller than the size of the battery element 100 when viewed in the X direction. For example, the length of the front cover member 210 in the Y direction may be shorter than the thickness of the battery element 100 in the Y direction. For example, a battery module may be formed by stacking multiple battery cells 10 in the Y direction. In this example, if the length of the front cover member 210 in the Y direction is shorter than the thickness of the battery element 100 in the Y direction, contact and interference between adjacent front cover members 210 in the Y direction can be suppressed. Furthermore, due to the tolerance of the thickness of the battery element 100 in the Y direction, the actual thickness of the battery element 100 in the Y direction may be thinner than the designed thickness of the battery element 100 in the Y direction. Even in this case, when the length of the front cover member 210 in the Y direction is shorter than the thickness of the battery element 100 in the Y direction, multiple battery cells 10 can be stably stacked in the Y direction to form a battery module.

[0029] 5 is a diagram for explaining a first example of a method for manufacturing the battery cell 10 according to the embodiment. In this first example, the battery cell 10 is manufactured as follows.

[0030] 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.

[0031] Next, the positive electrode tab 110 and the front cover member 210 are joined together. Similarly, the negative electrode tab 120 and the rear cover member 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 member 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 member 220 may be joined together.

[0032] Next, the exterior film 300 is wrapped around the battery element 100, the front cover member 210, and the rear cover member 220 in the X direction. This forms a wound portion 302 around the battery element 100, the front cover member 210, and the rear cover member 220 in the X direction. In addition, the excess length of the exterior film 300 is pulled out from the wound portion 302 as a pulled-out portion 304.

[0033] Next, the outer peripheral surface of the front lid member 210 in the X direction and the inner peripheral surface of the front opening of the wound portion 302 in the X direction are joined together by heat fusion, thereby forming the front sealed portion 510. Next, the outer peripheral surface of the rear lid member 220 in the X direction and the inner peripheral surface of the rear opening of the wound portion 302 in the X direction are joined together by heat fusion, thereby forming the rear sealed portion 520.

[0034] 5, the electrolyte is poured into the accommodating space 500 through the pouring opening 304c. The pouring opening 304c is formed by the gap between the first drawn-out portion 304a and the second drawn-out portion 304b.

[0035] Next, the storage space 500 is vacuum-sealed. Specifically, after evacuating the storage space 500 through the liquid inlet opening 304c, the first drawn-out section 304a and the second drawn-out section 304b are joined together by heat sealing to form the side sealing section 530. When the storage space 500 is evacuated, wrinkles may form in the exterior film 300. If wrinkles exist in the center section 330, the wrinkles are moved to at least one of the front section 310 and the rear section 320.

[0036] The drawer portion 304 is then folded along the top surface of the battery element 100 .

[0037] In this manner, the battery cell 10 is manufactured.

[0038] 6 is a diagram for explaining a second example of the method for manufacturing the battery cell 10 according to the embodiment. This second example is similar to the first example described above, except for the following points.

[0039] First, the battery element 100 is manufactured in the same manner as in the first example. Then, the positive electrode tab 110 and the front cover member 210 are joined together in the same manner as in the first example. Also, the negative electrode tab 120 and the rear cover member 220 are joined together. Then, the positive electrode tab 110 and the positive electrode current collector 102a are joined together in the same manner as in the first example. Also, the negative electrode tab 120 and the negative electrode current collector 104a are joined together.

[0040] Next, the exterior film 300 is wrapped around the battery element 100, the front cover member 210, and the rear cover member 220 in the X direction to form the wound portion 302 and the drawn portion 304. Next, the outer peripheral surface of the front cover member 210 in the X direction and the inner peripheral surface of the front opening of the wound portion 302 in the X direction are joined together by heat fusion, thereby forming the front sealed portion 510. Next, the outer peripheral surface of the rear cover member 220 in the X direction and the inner peripheral surface of the rear opening of the wound portion 302 in the X direction are joined together by heat fusion, thereby forming the rear sealed portion 520. Next, the first drawn portion 304a and the second drawn portion 304b are joined together by heat fusion, thereby forming the side sealed portions 530.

[0041] Next, as shown in FIG. 6, the electrolyte is injected into the accommodating space 500 through the liquid inlet 210a provided in the front cover member 210. Next, the accommodating space 500 is vacuum-sealed. Specifically, the accommodating space 500 is evacuated through the liquid inlet 210a, and then the liquid inlet 210a is closed with a predetermined cover member. Wrinkles may be formed in the exterior film 300 when the accommodating space 500 is evacuated. If wrinkles exist in the central portion 330, the wrinkles are moved to at least one of the front portion 310 and the rear portion 320. The liquid inlet may be provided in the rear cover member 220.

[0042] Next, in the same manner as in the first example, the drawn-out portion 304 is folded along the upper surface of the battery element 100.

[0043] In this manner, the battery cell 10 is manufactured.

[0044] 7 is a front perspective view of a battery cell 10A according to a modified example. The battery cell 10A according to the modified example is similar to the battery cell 10 according to the embodiment, except for the following points.

[0045] In the modified example, the positive electrode tab 110A is pulled out from approximately the center in the Y direction of the front cover member 210. The negative electrode tab 120A is pulled out from approximately the center in the Y direction of the rear cover member. In the modified example, a grouping of multiple positive electrode current collectors exists between the battery element and the positive electrode tab 110A. Similarly, a grouping of multiple negative electrode current collectors exists between the battery element and the negative electrode tab 120A. In the modified example, wrinkles exist in the exterior film 300 around these groupings. Therefore, in the modified example, the characteristics of the battery cell 10A can be stabilized in the same way as in the embodiment.

[0046] Although the embodiments and modifications 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.

[0047] For example, in the embodiment, the positive electrode tab 110 and the negative electrode tab 120 are arranged 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 arranged on only one of the front and rear sides of the battery element 100 in the X direction. In this case, the front end and rear end of the battery element 100 are covered by, for example, two lid materials. Alternatively, only the side of the battery element 100 from which the positive electrode tab 110 and the negative electrode tab 120 are pulled out may be covered by a lid material. In this example, an exterior film 300 may be sealed on the side of the battery element 100 opposite the lid material and folded along the battery element 100. [Explanation of symbols]

[0048] 10,10A battery cell 100 Battery Elements 102 Positive electrode 102a Positive electrode current collector 104 Negative electrode 104a Negative electrode current collector 110,110A positive tab 120,120A negative tab 210 Front lid material 210a Liquid injection hole 220 Rear lid material 300 exterior film 302 Wrapping part 304 Drawer part 304a 1st drawer part 304b 2nd drawer part 304c Liquid injection opening 310 Front 320 Rear part 330 Central part 500 storage spaces 510 Front sealing part 520 Rear sealing part 530 Side sealing part

Claims

1. A battery element having a longitudinal direction parallel to a first direction; a tab electrically connected to the battery element via a current collector aggregate portion drawn out from the battery element; a cover member that covers one end of the battery element on the first direction side and through which the tab is pulled out; an exterior film at least partially wrapped around the first direction of the battery element; Equipped with wrinkles are present in the exterior film around the gathering portion of the current collector in the first direction, The wrinkles are not present around the exterior film around the battery element in the first direction, a battery cell in which the tab and a portion of the exterior film located around the collecting portion of the current collector in the first direction are not connected to each other.

2. A battery cell as described in claim 1, wherein the size of the cover material is larger than the size of the battery element when viewed from the first direction.

3. A battery cell as described in claim 1, wherein the size of the cover material is smaller than the size of the battery element when viewed from the first direction.

Images