Battery cell

Abstract

The utility model provides a battery unit capable of inhibiting internal short circuit caused by damage of a partition plate. The battery cell is provided with an electrode body formed by alternately laminating a plurality of electrode sheets and separators. The plurality of electrode tabs have: a plurality of first electrode tabs, one end of which in the width direction is a protruding end protruding from one end of the separator in the width direction, the protruding end being integrated with the other protruding end at a predetermined position in the stacking direction, and constituting a current collector; and a plurality of second electrode sheets that face the first electrode sheets with the separator interposed therebetween, one end portion in the width direction being a non-protruding end portion disposed in a region facing the separator, and the direction of a flash formed at the non-protruding end portion and the flash of the other non-protruding end portion coincide in the direction toward the collector portion.

Description

Technical Field

[0001] The utility model relates to a battery unit. Background Art

[0002] Patent Document 1 below describes an electricity storage device comprising a current collecting element (electrode body) formed by alternating layers of multiple electrodes and separators, with tab terminals secured between the bottommost layer of the stacked electrodes and the underlying laminate film. In this electricity storage device, the ends of the stacked electrodes are brought together at predetermined positions in the stacking direction to form a current collecting portion connected to the tab terminals.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-196930.

[0004] However, the electrodes of an electrode assembly are cut into sheets during the initial manufacturing process. During this process, the cut surface undergoes plastic deformation, forming tiny burrs (protrusions) at the ends of the cut sheet electrodes.

[0005] As described in Patent Document 1, an electrode assembly is constructed by alternately stacking a plurality of electrode sheets and separators. The stacked plurality of electrode sheets includes a first electrode sheet having one end in the width direction protruding from the separator to form a current collecting portion, and a second electrode sheet opposing the first electrode sheet with one end in the width direction disposed in an area opposite the separator.

[0006] The first electrode sheet is bent into an R shape by leading one end in the width direction toward the collector. Therefore, the end in the width direction of the separator between the electrode sheets is also bent along the R direction of the first electrode sheet. Therefore, in the area opposite to the separator, when the direction of the flash formed at the end of the second electrode sheet is different from the direction toward the collector, it is possible that local stress is generated at the end of the separator due to interference from the flash. If the separator is damaged due to the occurrence of local stress, the risk of internal short circuit due to physical contact between the electrode sheets increases. Utility Model Content

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a battery cell capable of suppressing an internal short circuit caused by damage to a separator.

[0008] The battery cell of the first mode has an electrode body formed by alternately stacking a plurality of electrode sheets and separators, wherein the plurality of electrode sheets include: a plurality of first electrode sheets, each having an end portion on one side in the width direction being a protruding end portion protruding from an end portion on one side in the width direction of the separator, the protruding end portion being integrated together with other protruding end portions at a specified position in the stacking direction to constitute a collecting portion; and a plurality of second electrode sheets, each facing the first electrode sheet across the separator, having an end portion on one side in the width direction being a non-protruding end portion arranged in an area opposite to the separator, the direction of the burr formed on the non-protruding end portion being consistent with the burr of the other non-protruding end portions in a direction toward the collecting portion.

[0009] In the battery cell of the first embodiment, a plurality of electrode sheets and separators are alternately stacked. The plurality of electrode sheets are composed of a plurality of first electrode sheets and a plurality of second electrode sheets opposite to the plurality of first electrode sheets via separators. The first electrode sheet is provided with a protruding end portion having one end in the width direction protruding from the end portion in the width direction of the separator. The protruding end portion is integrated together with the protruding ends of the other first electrode sheets at a predetermined position in the stacking direction to constitute a current collecting portion. On the other hand, the second electrode sheet is provided with an end portion in the width direction being arranged at a non-protruding end portion in an area opposite to the separator. Here, the direction of the burr formed on the non-protruding end portion of the second electrode sheet is made consistent with the burr of the non-protruding end portion of the other second electrode sheets in a direction toward the current collecting portion. Therefore, it is possible to suppress the damage to the separator caused by the burr at the end portion of the second electrode sheet interfering with the area opposite to the separator. As a result, internal short circuits in the battery cell caused by separator damage are suppressed.

[0010] As described above, in the battery cell of the present invention, it is possible to suppress an internal short circuit caused by damage to the separator. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of a battery cell according to an embodiment as viewed from the thickness direction.

[0012] Figure 2 It is a schematic diagram of a battery cell according to the embodiment, viewed from a height direction in an exploded state.

[0013] Figure 3 It is an enlarged representation Figure 2 Schematic diagram of region P. DETAILED DESCRIPTION

[0014] The following reference Figures 1 to 3 The battery unit 20 according to one embodiment of the present invention will be described. Figures 1 to 3In each of the figures, the direction indicated by arrow W is the width direction of the battery cell 20, the direction indicated by arrow H is the height direction (vertical direction) of the battery cell 20, and the direction indicated by arrow D is the thickness direction of the battery cell 20. The width direction W of the battery cell 20 coincides with the width direction of the electrode sheet 50 and separator 60 described later.

[0015] Figure 1 This is a schematic diagram of a battery cell viewed from the thickness direction D. Figure 1 As shown, the battery cell 20 is formed in a flat and long rectangular plate shape with the width direction W as the longitudinal direction, and constitutes a secondary battery that can be charged and discharged.

[0016] The battery cell 20 includes an electrode body 40 and a laminate film 22 that seals the electrode body 40. The electrode body 40 is connected to an electrode lead 26 protruding in the width direction W at one end and the other end in the width direction W. The electrode lead 26 includes a first electrode lead 26A connected to the positive electrode of the electrode body 40 at one end in the width direction W and a second electrode lead 26B connected to the negative electrode of the electrode body 40 at the other end in the width direction W. The first electrode lead 26A and the second electrode lead 26B are formed into rectangular plates that are long in the width direction W. The laminate film 22 is embossed on at least one side in the thickness direction. By embossing, a concave receiving portion 221 is formed on the side surface to receive the electrode body 40 therein.

[0017] Figure 2 Schematic diagram of the battery unit 20 when viewed from the height direction H. Figure 2 As shown, the laminate film 22 includes a first laminate film 22A disposed on one side of the electrode body 40 in the thickness direction D and a second laminate film 22B disposed on the other side of the electrode body 40 in the thickness direction D. The first laminate film 22A and the second laminate film 22B overlap in the thickness direction D on both sides of the electrode body 40, and are thermally welded to each other at their outer peripheries to form a receiving space for the electrode body 40. In this embodiment, one side of the second laminate film 22B is embossed to form a receiving portion 221. The laminate film 22 can adopt both a single-cup embossing structure with one embossing location and a double-cup embossing structure with two embossing locations. In this embodiment, a single-cup embossing structure is adopted in which a receiving portion 221 with a drawing depth of approximately 8 mm to 10 mm is formed on one side of the second laminate film 22B.

[0018] On one side of the width direction W of the battery cell 20 , one end of the first electrode lead 26A protrudes from the end of the laminate film 22 in the width direction W. On the other side of the width direction W of the battery cell 20 , one end of the second electrode lead 26B protrudes from the end of the laminate film 22 in the width direction W.

[0019] One end of the electrode lead 26 protruding from the laminate film 22 is welded to a bus bar (not shown) at one end and the other end in the width direction W of the battery cell 20 .

[0020] The length CW1 of the battery cell 20 in the vehicle width direction is, for example, 530 mm to 600 mm, 600 mm to 700 mm, 700 mm to 800 mm, 800 mm to 900 mm, or 1000 mm or greater. The length CW2 of the region housing the electrode assembly is, for example, 500 mm to 520 mm, 600 mm to 700 mm, 700 mm to 800 mm, 800 mm to 900 mm, or 1000 mm or greater. The height CH of the battery cell 20 is, for example, 80 mm to 110 mm, or 110 mm to 140 mm. Furthermore, the thickness of the battery cell 20 is, for example, 5.0 mm to 7.0 mm, 7.0 mm to 9.0 mm, or 9.0 mm to 11.0 mm. The height TH of the electrode lead (terminal) 26 is, for example, 40 mm to 50 mm, 50 mm to 60 mm, or 60 mm to 70 mm.

[0021] The electrode body 40 is constructed by alternately stacking a plurality of electrode sheets 50 and separators 60. The plurality of electrode sheets 50 includes a plurality of positive electrode sheets 52 and a plurality of negative electrode sheets 54. In the electrode body 40, the positive electrode sheets 52 and the negative electrode sheets 54 are alternately stacked with separators 60 interposed therebetween. The positive electrode sheets 52 are an example of a "first electrode sheet," and the negative electrode sheets 54 are an example of a "second electrode sheet."

[0022] The positive electrode sheet 52 includes a sheet-shaped positive electrode current collector (electrode current collector) 521 and a positive electrode active material layer (electrode active material layer) 522 coated on the surface of the positive electrode current collector 521 (see Figure 3 The positive electrode current collector 521 is composed of, for example, a metal foil such as aluminum foil. The positive electrode active material layer 522 contains a positive electrode active material and a positive electrode binder. The positive electrode active material is a substance capable of intercalating and deintercalating ions. For lithium-ion secondary batteries, for example, it can be composed of lithium nickel oxides, lithium cobalt oxides (such as LiCoO2), and lithium manganese oxides (such as LiMn2O4).

[0023] One end of the positive electrode sheet 52 in the width direction W is a protruding end 50A that protrudes from one end of the separator 60 in the width direction. This protruding end 50A is composed of an uncoated portion that is not coated with the positive electrode active material layer 522, and the positive electrode current collector 521 is exposed. The protruding end 50A is integrated with the protruding ends 50A of other positive electrode sheets 52 in the stacking direction ( Figure 2 The predetermined position of the positive electrode side current collecting portion 56 (refer to Figure 3In this embodiment, the protruding ends 50A of the plurality of positive electrode sheets 52 are integrated on the first laminate film 22A side, and the first electrode lead 26A is disposed between the positive electrode-side current collector 56 and the first laminate film 22A. This connects the first electrode lead 26A to the positive electrode-side current collector 56.

[0024] On the other hand, the other end of the positive electrode sheet 52 in the width direction W is a non-protruding end 50B arranged in the area facing the separator 60. The non-protruding end 50B is composed of a coated portion coated with the positive electrode active material layer 522. The non-protruding end 50B is arranged so as not to protrude from the other end of the separator 60 in the width direction W and faces the second electrode sheet 50 across the separator 60.

[0025] The negative electrode sheet 54 includes a sheet-shaped negative electrode current collector (electrode current collector) 541 and a negative electrode active material layer (electrode active material layer) 542 coated on the surface of the negative electrode current collector 541 (see Figure 3 The negative electrode current collector 541 is formed of, for example, a metal foil such as copper foil. The negative electrode active material layer 542 contains a negative electrode active material and a negative electrode binder. The negative electrode active material is a substance capable of intercalating and deintercalating ions. For example, in a lithium-ion secondary battery, it can be formed of a carbon material, a fluororesin (e.g., polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, etc.), polyvinyl acetate, etc.

[0026] One end portion of the negative electrode sheet 54 in the width direction W is a non-protruding end portion 50B disposed in a region facing the separator 60. The non-protruding end portion 50B is formed by a coated portion of the negative electrode active material layer 542. The non-protruding end portion 50B is disposed so as not to protrude from one end portion of the separator 60 in the width direction W and faces the second electrode sheet 50 across the separator 60.

[0027] Meanwhile, the other end of the negative electrode sheet 54 in the width direction W is a protruding end 50A that protrudes from one end of the separator 60 in the width direction. This protruding end 50A is an uncoated portion not coated with the negative electrode active material layer 542, exposing the negative electrode current collector 541. The protruding end 50A, along with the protruding ends 50A of the other negative electrode sheets 54, is integrated with the first laminate film 22A side to form the negative electrode-side current collector 56. In this embodiment, a second electrode lead 26B is disposed between the negative electrode-side current collector 56 and the first laminate film 22A. This connects the second electrode lead 26B to the negative electrode-side current collector 56.

[0028] Figure 3 Enlarged representation Figure 2 The region P is shown in FIG. The region P indicates a region on one side in the width direction W of the electrode body 40 .

[0029] like Figure 3As shown, on one side of the width direction W of the electrode body 40, the protruding end portions 50A of the stacked plurality of positive electrode sheets 52 are led out toward the collector portion 56 in the first direction D1 along the stacking direction. Therefore, the protruding end portions 50A of the plurality of positive electrode sheets 52 are bent into an R-shape. In addition, the end portion of the separator 60 between the positive electrode sheet 52 and the negative electrode sheet 54 on one side of the width direction W is also bent along the R-direction of the positive electrode sheet 52. In this way, the end portion of the separator 60 bent into an R-shape by the positive electrode sheet 52 contacts the edge of the non-protruding end portion 50B on one side of the width direction W of the negative electrode sheet 54. Therefore, if the non-protruding end portion 50B of the negative electrode sheet 54 strongly interferes with the separator 60, local stress concentration may occur.

[0030] Here, the positive electrode sheet 52 or the negative electrode sheet 54 is cut into sheets in the initial process of manufacturing. At this time, due to plastic deformation of the cut surface, a small burr 70 (protrusion) is formed at the end of the positive electrode sheet 52 and the negative electrode sheet 54 (see Figure 3 It should be noted that the "flash" referred to here primarily refers to the burrs formed by deformation of the cut surface of the electrode current collector made of metal foil. If the direction of the burrs 70 differs from the curvature direction of the separator 60, there is a possibility that the burrs 70 will strongly interfere with the separator 60.

[0031] In this embodiment, the burrs 70 formed on the non-protruding end 50B of the protruding end 50A of the negative electrode sheet 54 are oriented in the direction toward the current collecting portion 56 (at the same direction as the burrs 70 on the non-protruding end 50B of the other negative electrode sheets 54). Figure 3 Therefore, the direction of the burr 70 formed on the non-protruding end 50B is along the R direction of the partition 60, so that strong interference between the burr 70 of the non-protruding end 50B and the partition 60 can be suppressed.

[0032] The above-mentioned problem of local stress concentration relative to the separator 60 also exists in the portion where the protruding end 50A of the negative electrode sheet 54 is led out toward the collector 56 on the negative electrode side and bent into an R shape on the other side of the width direction W of the electrode body 40. That is, it is also desirable to avoid strong interference between the non-protruding end 50B of the positive electrode sheet 52 and the separator 60 on the other side of the width direction W of the electrode body 40. Therefore, although not shown in the figure, in the protruding end 50A on the other side of the width direction W of the positive electrode sheet 52, the direction of the burr 70 formed on the non-protruding end 50B is toward the collector 56 ( Figure 3 The first direction D1 side is consistent.

[0033] The separator 60 is an insulating layer that maintains a gap between the positive electrode sheet 52 and the negative electrode sheet 54 to prevent contact short circuits and also retains the non-aqueous electrolyte. The separator 60 is formed, for example, from a porous resin flat plate. In this embodiment, the battery cell 20 includes a plurality of separators 60 cut into sheets, with one separator 60 positioned between the positive electrode sheet 52 and the negative electrode sheet 54. When viewed in the stacking direction of the electrode assembly 40, the protruding end 50A of the positive electrode sheet 52 protrudes from one end of the separator 60 in the width direction W. The protruding end 50A of the negative electrode sheet 54 protrudes from the other end of the separator 60 in the width direction W.

[0034] The manufacturing method of the battery cell 20 includes, for example, an initial step, a burr direction inspection step, a lamination step, a pressing step, a terminal welding step, a cell drying step, a liquid injection / sealing step, an activation step, and an evaluation step.

[0035] In the initial process, the positive electrode sheet 52, the negative electrode sheet 54, and the separator 60 constituting the electrode body 40 are formed. The positive electrode sheet 52 and the negative electrode sheet 54 are cut into sheets in a state where the electrode active material is applied to the electrode collector. In the burr direction inspection process, the direction of the burrs at the ends of the cut surfaces of the positive electrode sheet 52 and the negative electrode sheet 54 cut into sheets is inspected. In this burr direction inspection process, the direction of the burrs at the ends constituting the non-protruding ends 50B is inspected at least in the electrode body 40. In the stacking process, the positive electrode sheets 52 and the negative electrode sheets 54 are stacked alternately with the separator 60 therebetween. At this time, the direction of the burrs at the non-protruding ends of the positive electrode sheet 52 and the negative electrode sheet 54 is the same as the direction toward the collector 56 ( Figure 3 In the pressing process, the electrode body 40 is formed by pressing a stacked body in which the positive electrode sheets 52 and the negative electrode sheets 54 are alternately stacked with the separator 60 in the stacking direction. In the terminal welding process, the electrode lead 26 is welded on one side and the other side of the width direction W of the electrode body 40. In the cell drying process, the electrode body 40 is vacuum dried to remove the moisture contained in the electrode body 40. In the injection / sealing process, the electrode body 40 is sealed with a laminate film, and the electrolyte is injected into the interior to form a battery cell 20. In the activation process, the battery cell 20 is initially charged and then subjected to a high-temperature aging treatment. In the evaluation process, the cell voltage, battery resistance, etc. are checked and the battery cell 20 that exhibits the specified performance is selected.

[0036] As described above, in the battery cell 20 of the present embodiment, a plurality of electrode sheets 50 and separators 60 are alternately stacked. The plurality of electrode sheets 50 are composed of a plurality of positive electrode sheets 52 and a plurality of negative electrode sheets 54 facing the plurality of positive electrode sheets 52 via the separator 60. The positive electrode sheet 52 is provided with a protruding end portion 50A protruding from an end portion of the separator 60 on one side in the width direction W. The protruding end portion 50A is integrated together with the protruding end portion 50A of another positive electrode sheet 52 at a predetermined position in the stacking direction to constitute a current collecting portion 56 on the positive electrode side. On the other hand, the negative electrode sheet 54 is provided with a non-protruding end portion 50B arranged at an end portion on one side in the width direction W in an area facing the separator 60. Here, the direction of the burr 70 formed on the non-protruding end portion 50B of the negative electrode sheet 54 is in the direction toward the current collecting portion 56 on the positive electrode side together with the burr 70 of the non-protruding end portion 50B of the other negative electrode sheet 54 ( Figure 3 The burrs 70 at the ends of the negative electrode sheets 54 are aligned in the first direction D1). Therefore, damage to the separator 60 caused by interference between the burrs 70 at the opposing regions of the separator 60 can be suppressed. Consequently, internal short circuits in the battery cell 20 caused by damage to the separator 60 can be suppressed.

Claims

1. A battery cell comprising an electrode body formed by alternately stacking a plurality of electrode sheets and separators, characterized in that: The plurality of electrode sheets have: a plurality of first electrode sheets, one end of which in the width direction is a protruding end protruding from one end of the separator in the width direction, the protruding end being integrated with other protruding ends at a predetermined position in the stacking direction to constitute a current collecting portion; and A plurality of second electrode sheets are provided, which are opposite to the first electrode sheet across the partition, and whose ends on one side in the width direction are non-protruding ends arranged in the area opposite to the partition, and the direction of the burrs formed on the non-protruding ends is consistent with the direction of the burrs on other non-protruding ends toward the collecting part.

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