Battery cell

Abstract

The utility model provides a battery unit and a manufacturing method of the battery unit. The battery unit can restrain cost rise caused by increase of the number of parts and can restrain short circuit near an electrode lead. The battery cell is provided with: an electrode body in which a positive electrode sheet and a negative electrode sheet, which are electrode sheets, are laminated with a separator therebetween; and a laminated film that seals the electrode body. And an electrode lead that is connected to an uncoated portion where the sheet-shaped current collector is not coated with the electrode active material at at least one end portion in the width direction of the electrode sheet, and that is led out from the sealed end portion of the laminated film. The uncoated portion is formed so as to include a base end position of an R region bent into an R shape toward the sealed end portion at the end portion in the width direction of the electrode sheet.

Description

Technical Field

[0001] The utility model relates to a battery unit and a manufacturing method of the battery unit. Background Art

[0002] Patent Document 1 below describes a laminated film battery cell having a storage cell formed by laminating a positive electrode and a negative electrode with a separator interposed therebetween, a laminated film sealing the storage cell, and a current collecting tab connected to the cell and extending from a sealed end of the laminated film.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-061895.

[0004] The battery element described in Patent Document 1, for example, comprises an electrode assembly formed by stacking positive and negative electrode sheets with a separator interposed therebetween. The electrode sheets' current collectors are formed with a coated portion coated with an electrode active material and an uncoated portion uncoated with the electrode active material. The coated portion of one electrode sheet is positioned opposite the coated portion of another electrode sheet, with the separator interposed therebetween. This allows electrolyte (ions) to enter and exit (intercalate) between the coated portions, contributing to the battery reaction. Furthermore, the uncoated portion is positioned at one end of the electrode sheet in the width direction, extending from the separator, and is connected to an electrode lead.

[0005] However, in battery cells where the electrode bodies are sealed with a laminate film, the ends of the electrode sheets and separators are bent into an R-shape toward the sealed ends of the laminate film. This causes the ends of the separators, which ensure insulation between the electrode sheets, to shift position, and the coated portions of the R-shaped electrode sheets to come into direct contact with the coated portions of other electrode sheets, potentially causing a short circuit.

[0006] To prevent short circuits, an insulating protective film is applied to the ends of the electrode sheets where the electrode body and the electrode lead are connected. However, this short circuit prevention measure using a protective film has the problem of increased costs due to the increased number of parts. Utility Model Content

[0007] The present invention takes the above-mentioned facts into consideration and aims to provide a battery cell and a method for manufacturing the battery cell that can suppress cost increases due to an increase in the number of components and can suppress short circuits near electrode leads.

[0008] The battery cell of the first mode comprises an electrode body formed by stacking a positive electrode sheet and a negative electrode sheet as electrode sheets with a separator therebetween, a laminate film that seals the electrode body, and an electrode lead connected to an uncoated portion of a sheet-shaped current collector on which an electrode active material is not coated at at least one end in the first width direction of the electrode sheet and extending from the sealed end of the laminate film, wherein the uncoated portion is formed as a base end position of an R region that is bent into an R shape toward the sealed end at the end in the first width direction of the electrode sheet.

[0009] The battery cell of the first embodiment includes an electrode body formed by stacking a positive electrode sheet and a negative electrode sheet with a separator interposed therebetween. The electrode body is connected to an electrode lead at at least one end of the electrode sheet in the first width direction. The electrode lead is connected to an uncoated portion of the sheet-shaped current collector in the electrode sheet where the electrode active material is not applied, and is led out of the battery cell from the sealed end of the laminate film.

[0010] However, in battery cells where the electrode bodies are sealed with a laminate film, the ends of the electrode sheets and separators are bent into an R-shape toward the sealed ends of the laminate film. This causes the ends of the separators, which ensure insulation between the electrode sheets, to shift position, and the coated portions of the R-shaped electrode sheets to come into direct contact with the coated portions of other electrode sheets, potentially causing a short circuit.

[0011] Here, according to the first embodiment, the uncoated portion of the electrode sheet is formed to include the base end position of the R region bent into an R shape toward the sealed end at the end in the first width direction. Therefore, the coated portion of the electrode sheet is not formed within the R region. As a result, it is possible to suppress direct contact between the coated portions of the electrode sheets caused by the positional offset of the ends of the separator, and ensure insulation between the electrode sheets without the need for an insulating protective sheet. As a result, it is possible to suppress the cost increase caused by the increase in the number of components, and to suppress the occurrence of short circuits near the electrode leads.

[0012] The battery cell of the second embodiment is the battery cell of the first embodiment, wherein the length of the uncoated portion in a second width direction perpendicular to the first width direction is set to be shorter than the length of the coated portion in the electrode sheet where the electrode active material is coated on the current collector.

[0013] In a battery cell where the electrode body is sealed with a laminate film, making the uncoated portion of the electrode sheet smaller than the coated portion facilitates connection to the electrode lead. On the other hand, positional misalignment between the electrode sheet and the separator ends is more likely to occur in the R region of the electrode body.

[0014] According to the second embodiment, in the electrode sheet, the uncoated portion is formed so that the length in the second width direction, which is perpendicular to the first width direction, is shorter than the length in the second width direction of the coated portion, including the base end of the R region. Therefore, connection to the electrode lead can be facilitated, and short circuits can be effectively suppressed at locations on the coated portion of the electrode sheet that are susceptible to short circuits due to bending.

[0015] A battery cell according to a third aspect is the battery cell according to the first aspect or the second aspect, wherein the electrode assembly is configured such that the length of the uncoated portion in the first width direction increases as the electrode sheet is arranged on the outer side relative to the sealed end portion.

[0016] In a battery cell in which the electrode assembly is sealed with a laminate film, the curvature of the R region increases as the electrode tab is positioned farther outward from the sealed end of the laminate film. This makes it more likely that the electrode tab and separator ends will be misaligned.

[0017] In the battery cell of the third embodiment, the length of the uncoated portion in the first width direction increases as the electrode sheet is positioned toward the outer layer relative to the sealed end. Therefore, the length of the uncoated portion in the first width direction is set longer in areas where short circuits due to bending of the coated portion of the electrode sheet are more likely to occur, effectively preventing short circuits.

[0018] The manufacturing method of the battery cell of the fourth embodiment is a method for manufacturing the battery cell described in the first embodiment, comprising: a process of coating an electrode active material on the collector; and a process of removing the electrode active material coated on the end portion of the collector in the first width direction and in the area including the base end position of the R area.

[0019] In the fourth embodiment of the battery cell manufacturing method, after applying the electrode active material to the current collector, the applied electrode active material is removed from the end portion of the current collector in the first width direction, i.e., the region including the base end position of the R region, to manufacture the battery cell. This allows for a battery cell that can suppress component-related cost increases and prevent short circuits near the electrode leads. Furthermore, in the fourth embodiment, since the electrode active material is removed from the end portion of the current collector in the first width direction after application of the electrode active material, the occurrence of "edge protrusion," where the thickness of the electrode active material layer increases at the boundary between the coated and uncoated portions, can be suppressed.

[0020] As described above, in the battery cell and the method for manufacturing the battery cell of the present invention, it is possible to suppress a cost increase due to an increase in the number of components and to suppress the occurrence of a short circuit near the electrode lead. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic plan view showing the main parts of a vehicle to which the battery pack according to the embodiment is applied.

[0022] Figure 2 It is a schematic perspective view of a battery module according to the embodiment.

[0023] Figure 3 It is a plan view of the battery module according to the embodiment in a state where the upper cover of the module case is removed.

[0024] Figure 4 This is a schematic diagram of the battery cells housed in the battery module as viewed from the thickness direction.

[0025] Figure 5This is a schematic diagram of a battery cell showing the battery cell in an exploded manner.

[0026] Figure 6A It will Figure 5 An enlarged side view showing a partially cutaway end portion of one width direction of the battery cell shown in the region P,

[0027] Figure 6B It is a rough representation of the Figure 6A This is a cross-sectional view of a battery cell cut along line 6B-6B. DETAILED DESCRIPTION

[0028] The following reference Figures 1 to 6B An embodiment of the present invention will be described.

[0029] The overall structure of vehicle 100 will be described below. Figure 1 1 is a schematic top view showing the main parts of a vehicle 100 to which the battery pack 10 according to the embodiment is applied. Figure 1 As shown, vehicle 100 is an electric vehicle (BEV) with a battery pack 10 mounted under the floor. Arrows UP, FR, and LH in the figures indicate the upper side in the vehicle vertical direction, the front side in the vehicle longitudinal direction, and the left side in the vehicle width direction, respectively. When front, rear, left, right, up, and down are used for description, unless otherwise specified, these directions refer to front and rear in the vehicle longitudinal direction, left and right in the vehicle width direction, and up and down in the vehicle vertical direction.

[0030] As an example, vehicle 100 of this embodiment includes a DC / DC converter 102, an electric compressor 104, and a PTC (Positive Temperature Coefficient) heater 106 disposed toward the front of battery pack 10. Furthermore, a motor 108, a gearbox 110, an inverter 112, and a charger 114 are disposed toward the rear of battery pack 10.

[0031] The DC current output from battery pack 10 is voltage-regulated by DC / DC converter 102 and then supplied to electric compressor 104, PTC heater 106, inverter 112, etc. Furthermore, by supplying power to motor 108 via inverter 112, the rear wheels rotate, causing vehicle 100 to travel.

[0032] A charging port 116 is provided on the right side of the rear portion of the vehicle 100 . By connecting a charging plug of an external charging device (not shown) to the charging port 116 , electricity can be stored in the battery pack 10 via the on-board charger 114 .

[0033] The arrangement and structure of the components comprising vehicle 100 are not limited to the configuration described above. For example, the present invention may also be applied to a hybrid vehicle (HV) or a plug-in hybrid electric vehicle (PHEV) equipped with an engine. Furthermore, in this embodiment, a rear-wheel drive vehicle is shown with motor 108 mounted at the rear of the vehicle. However, the present invention is not limited to this. A front-wheel drive vehicle may also be shown with motor 108 mounted at the front of the vehicle, or a pair of motors 108 may be mounted at the front and rear of the vehicle. Furthermore, a vehicle may also have an in-wheel motor in each wheel.

[0034] Here, the battery pack 10 is configured to include a plurality of battery modules 11. In this embodiment, ten battery modules 11 are provided as an example. Specifically, five battery modules 11 are arranged in the vehicle front-to-rear direction on the right side of the vehicle 100, and five battery modules 11 are arranged in the vehicle front-to-rear direction on the left side of the vehicle 100. Furthermore, the battery modules 11 are electrically connected.

[0035] Figure 2 Schematic diagram of the battery module 11. Figure 2 As shown, the battery module 11 includes a module housing 16 that serves as an outer shell. The module housing 16 is formed into a generally rectangular parallelepiped shape, with its longitudinal direction being the vehicle width direction. Furthermore, the module housing 16 is made of an aluminum alloy. For example, the module housing 16 is formed by joining aluminum die-castings at both ends of an aluminum alloy extrusion using laser welding or other methods.

[0036] A pair of voltage terminals 12 and a connector 14 are provided at both ends of the battery module 11 in the vehicle width direction. A flexible printed circuit board 21, described later, is connected to the connector 14. Bus bars (not shown) are welded to both ends of the battery module 11 in the vehicle width direction.

[0037] The battery module 11 has a vehicle widthwise length MW of, for example, 350 mm to 600 mm, a vehicle longitudinal length ML of, for example, 150 mm to 250 mm, and a vehicle vertical height MH of, for example, 80 mm to 110 mm.

[0038] Figure 3 FIG. 1 is a top view of the battery module 11 with the upper cover removed. Figure 3 As shown, a plurality of battery cells 20 are stacked within the module case 16. Each battery cell 20 is housed with its thickness oriented in the stacking direction. In this embodiment, 24 battery cells 20 are arranged (stacked) in the vehicle's longitudinal direction and bonded together to form a stacked structure.

[0039] In addition, in order to make the explanation easier to understand, Figures 3 to 6BIn each of the figures, the direction indicated by the arrow W is the width direction of the battery cell 20, the direction indicated by the arrow H is the height direction (vertical direction) of the battery cell 20, and the direction indicated by the arrow D is the thickness direction of the battery cell 20. The width direction W is an example of a "first width direction," and the height direction H, which is orthogonal to the width direction W, is an example of a "second width direction."

[0040] The width direction of the laminate film 22 described below coincides with the width direction W of the battery cell 20 . The height direction of the laminate film 22 coincides with the height direction H of the battery cell 20 . The thickness direction of the laminate film 22 coincides with the thickness direction D of the battery cell 20 .

[0041] A flexible printed circuit (FPC) 21 is placed on the battery cell 20. The FPC 21 is formed into a strip with its longitudinal direction extending across the width of the vehicle. Thermistors 23 are located at each end of the FPC 21. The thermistors 23 are not bonded to the battery cell 20 but are pressed toward the battery cell 20 by the upper cover of the battery module 11.

[0042] Furthermore, one or more cushioning materials (not shown) are housed within the module housing 16. For example, the cushioning material is a thin, elastically deformable plate-like member disposed between adjacent battery cells 20, with the thickness of the battery cells 20 arranged in the direction of their thickness. In this embodiment, as an example, cushioning materials are disposed at both longitudinal ends and the longitudinal center of the module housing 16.

[0043] Figure 4 This is a schematic diagram of a battery cell viewed from the thickness direction D. Figure 4 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.

[0044] 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.

[0045] Figure 5Schematic diagram of the battery unit 20 when viewed from the height direction H. Figure 5 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 fused to each other at their outer peripheries to form a housing space for the electrode body 40. Hereinafter, the portion where the outer peripheries of the first laminate film 22A and the second laminate film 22B are thermally fused to each other is referred to as a sealed end portion 30.

[0046] In this embodiment, one side of the second laminate film 22B is embossed to form a receiving portion 221. The laminate film 22 can have either a single-cup embossed structure with one embossed location or a double-cup embossed structure with two embossed locations. In this embodiment, a single-cup embossed structure is used in which a receiving portion 221 with a drawn depth of approximately 8 mm to 10 mm is formed on one side of the second laminate film 22B.

[0047] 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.

[0048] 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 .

[0049] 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 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 40 mm to 50 mm, 50 mm to 60 mm, or 60 mm to 70 mm.

[0050] The electrode body 40 is formed 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.

[0051] The positive electrode sheet 52 is formed by applying a positive electrode active material (electrode active material) 522 onto the surface of a sheet-like positive electrode current collector (electrode current collector) 521 (see Figure 6B ). The positive electrode sheet 52 includes a coated portion 52A where the positive electrode active material 522 is coated on the surface of the positive electrode current collector 521 , and an uncoated portion 52B where the positive electrode active material 522 is not coated on the surface of the positive electrode current collector 521 .

[0052] The positive electrode current collector 521 is made of, for example, a metal foil such as aluminum foil. The positive electrode active material 522 contains a positive electrode active material and a positive electrode binder. The positive electrode active material 522 is a substance capable of intercalating and deintercalating ions. For lithium-ion secondary batteries, for example, it can be made of lithium nickel oxides, lithium cobalt oxides (such as LiCoO2), and lithium manganese oxides (such as LiMn2O4).

[0053] The uncoated portion 52B is provided at one end of the positive electrode sheet 52 in the width direction W. The front end of the uncoated portion 52B protrudes from one end of the separator in the width direction W and is integrated with the uncoated portions 52B of other positive electrode sheets 52 in the stacking direction ( Figure 5 The predetermined position in the thickness direction D) constitutes the current collecting portion 56 on the positive electrode side (refer to Figure 6B In this embodiment, the uncoated portions 52B of the plurality of positive electrode sheets 52 are integrated on the first laminate film 22A side, and a 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. Furthermore, one end of the first electrode lead 26A extends from the sealed end portion 30 between the first laminate film 22A and the second laminate film 22B near the positive electrode-side current collector 56 to the exterior of the battery cell 20.

[0054] On the other hand, the other end of the positive electrode sheet 52 in the width direction W is a non-protruding end arranged in a region facing the separator 60. This non-protruding end is composed of a coated portion 52A coated with the positive electrode active material 522, and is arranged so as not to protrude from the other end of the separator 60 in the width direction W, and faces the negative electrode sheet 54 with the separator 60 interposed therebetween.

[0055] The negative electrode sheet 54 is formed by applying a negative electrode active material (electrode active material) 542 on the surface of a sheet-like negative electrode current collector (electrode current collector) 541 (see Figure 6B ). The negative electrode sheet 54 includes a coated portion 54A where the negative electrode active material 542 is coated on the surface of the negative electrode current collector 541 , and an uncoated portion 54B where the negative electrode active material 542 is not coated on the surface of the negative electrode current collector 541 .

[0056] The negative electrode current collector 541 is made of, for example, a metal foil such as copper foil. The negative electrode active material 542 contains a negative electrode active material and a negative electrode binder. The negative electrode active material 542 is a substance capable of intercalating and deintercalating ions. For lithium-ion secondary batteries, it can be made of, for example, a carbon material, a fluororesin (e.g., polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer), or polyvinyl acetate.

[0057] The end portion of the negative electrode sheet 54 in the width direction W is a non-protruding end portion disposed in a region facing the separator 60. This non-protruding end portion is formed by a coating portion 54A coated with a negative electrode active material 542, and is configured so as not to protrude from the end portion of the separator 60 in the width direction W and to face the second electrode sheet 50 across the separator 60.

[0058] On the other hand, an uncoated portion 54B is provided at the other end portion in the width direction W of the negative electrode sheet 54. The front end of the uncoated portion 54B protrudes from the other end portion in the width direction W of the separator and is integrated with the uncoated portions 54B of the other negative electrode sheets 54 in the stacking direction ( Figure 5 The negative electrode side current collecting portion 56 is formed at a predetermined position in the thickness direction D). Figure 6B In this embodiment, a second electrode lead 26B is disposed between the negative-side current collector 56 and the first laminate film 22A. This connects the second electrode lead 26B to the negative-side current collector 56. Furthermore, one end of the second electrode lead 26B extends from the sealed end portion 30 between the first and second laminate films 22A, 22B, near the negative-side current collector 56 to the exterior of the battery cell 20.

[0059] Figure 6A It will Figure 5 The end portion of the battery cell 20 in the width direction W shown in the region P is partially cut away and shown in an enlarged side view. Figure 6B For the Figure 6A An enlarged cross-sectional view of the end portion of the battery cell 20 cut along line 6B-6B.

[0060] like Figure 6A As shown, the length L2 of the uncoated portion 52B of the positive electrode sheet 52 in the height direction H is set to be shorter than the length L1 of the coated portion 52A in the height direction H, corresponding to the width of the first electrode lead 26A. Furthermore, although not shown, the length of the uncoated portion 54B of the negative electrode sheet 54 in the height direction H is also set to be shorter than the length of the coated portion 54A in the height direction.

[0061] On the other hand, Figure 6B As shown, at the ends of the battery cell 20 in the width direction W, an R region 40R is formed where the ends of the electrode sheet 50 (positive electrode sheet 52, negative electrode sheet 54) and the separator 60 are bent into an R shape toward the sealed end 30 of the laminate film. Figure 6B 4 shows the base end 40R1 and the tip 40R2 of the R region 40R of the positive electrode sheet 52. As shown in the figure, the uncoated portion 52B of the positive electrode sheet 52 is formed to include the base end 40R1 of the R region 40R. Therefore, the uncoated portion 52B of the positive electrode sheet 52 extending toward the current collector 56 is arranged in the R region 40R at one end in the width direction W of the electrode body 40.

[0062] Here, the uncoated portion 52B of the positive electrode sheet 52 is set so that the length L3 in the width direction W increases as the positive electrode sheet is positioned toward the outermost layer of the electrode assembly 40. For example, the boundary between the coated portion 52A and the uncoated portion 52B of the outermost positive electrode sheet 52 is located at the base end position 40R1 of the R region 40R. For other positive electrode sheets 52 positioned inward relative to the outermost electrode sheet 50X, the boundary between the coated portion 52A and the uncoated portion 52B is offset further outward (to one side in the width direction W) than the base end position 40R1 of the R region 40R as the positive electrode sheet 52 is positioned toward the innermost layer.

[0063] Although not shown, the uncoated region located on the other side of the negative electrode sheet 54 in the width direction W also has a similar configuration. Specifically, the uncoated portion 54B of the negative electrode sheet 54 is formed to include the base end of the R region 40R. Therefore, the uncoated portion 54B of the negative electrode sheet 54 extending toward the current collector 56 is located in the R region 40R at the other end of the electrode body 40 in the width direction W. Furthermore, the uncoated portion 54B of the negative electrode sheet 54 is configured so that the closer the negative electrode sheet 54 is to the outer layer of the electrode body 40, the longer its length in the width direction W.

[0064] The separator 60 is an insulating layer that maintains the 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 composed of, for example, 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 body 40, the uncoated portion 52B of the positive electrode sheet 52 protrudes from one end of the separator 60 in the width direction W. The uncoated portion 54B of the negative electrode sheet 54 protrudes from the other end of the separator 60 in the width direction W.

[0065] The battery cell manufacturing method is described below. Taking the battery cell 20 described above as an example, the battery cell is manufactured through an initialization step, a stacking step, a pressing step, a terminal welding step, a cell drying step, a liquid injection / sealing step, an activation step, and an evaluation step.

[0066] In the initial step, the positive electrode sheet 52 , the negative electrode sheet 54 , and the separator 60 constituting the electrode assembly 40 are formed.

[0067] In this initial step, a coating process is performed to apply electrode active material to the electrode collectors of the positive electrode sheet 52 and the negative electrode sheet 54, which serve as the electrode sheet 50. Here, the positive electrode sheet 52 is used as an example for explanation. In the coating process, an uncoated portion is formed at one end of the positive electrode collector 521 in the width direction W. The length of the uncoated portion in the width direction W in this process is set to be smaller than the length of the R region 40R in the width direction W when the electrode body 40 is formed. In other words, in this process, the coated portion 52A is formed at the base end position 40R1 of the R region 40R of the positive electrode sheet 52.

[0068] In the initial process, after the coating process, a removal process is performed to remove the positive electrode active material from the surface of the positive electrode current collector 521. In this removal process, the positive electrode active material 522 is removed from a predetermined region at one end in the width direction W of the positive electrode current collector 521, that is, including the base end position 40R1 of the R region 40R, using a known doctor blade method, for example. This allows the uncoated portion 52B of the positive electrode sheet 52 to be formed, including the base end position 40R1 of the R region 40R. This process also removes the so-called "edge protrusion" formed on the edge surface at the boundary between the coated portion 52A and the uncoated portion 52B of the positive electrode sheet 52, where the thickness of the positive electrode active material 522 layer is thicker than that of other portions.

[0069] In the stacking process, the positive electrode sheets 52 and the negative electrode sheets 54 are alternately stacked with the separator 60 therebetween. In the pressing process, the stacked body formed by alternately stacking the positive electrode sheets 52 and the negative electrode sheets 54 with the separator 60 therebetween is pressed in the stacking direction to form the electrode body 40. 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 the battery cell 20. In the activation process, the battery cell 20 is initially charged and then subjected to high-temperature aging treatment. In the evaluation process, the cell voltage, battery resistance, etc. are inspected and the battery cell 20 that exhibits the specified performance is selected.

[0070] The battery cell 20 of the above-described embodiment can be manufactured through the above-described steps.

[0071] 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 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 40 mm to 50 mm, 50 mm to 60 mm, or 60 mm to 70 mm.

[0072] The following describes the functions and effects of the present invention. As described above, the battery cell 20 of this embodiment includes an electrode body 40 formed by laminating a positive electrode sheet 52 and a negative electrode sheet 54 as electrode sheets 50 with a separator 60 interposed therebetween. The electrode body 40 is connected to the electrode lead 26 at at least one end of the electrode sheet 50 in the first width direction W. The electrode lead 26 is connected to the uncoated portions 52B and 54B of the sheet-shaped current collectors (positive electrode current collector 521 and negative electrode current collector 541) in the electrode sheet 50, where the electrode active material is not applied. The electrode lead 26 is then extended from the sealed end 30 of the laminate film 22 to the outside of the battery cell 20.

[0073] However, in the battery cell 20 in which the electrode body 40 is sealed by the laminate film 22, an R region 40R (see FIG. 4 ) is formed in which the ends of the electrode sheet 50 and the separator 60 are bent in an R shape toward the sealed end 30 of the laminate film 22. Figure 6B In the R region 40R, the ends of the separators 60 that ensure insulation between the electrode sheets 50 are prone to positional misalignment. Therefore, if the coated portions 52A and 54A of the electrode sheets 50 are arranged in the R region 40R, there is a risk of short circuits due to direct contact with the coated portions 52A and 54A of other electrode sheets 50. To prevent such short circuits, if insulating protective sheets are arranged at the ends of the electrode sheets 50, there is a problem of increased cost due to the increase in components.

[0074] In contrast, according to this embodiment, the uncoated portions 52B and 54B of the electrode sheet 50 are formed to include the base end position 40R1 of the R region 40R. Therefore, the coated portions 52A and 54A of the electrode sheet 50 are not formed within the R region. This prevents direct contact between the coated portions of the electrode sheet 50 caused by positional misalignment of the ends of the separator 60, and ensures insulation between the electrode sheets 50 without using an insulating protective sheet. As a result, cost increases due to an increase in the number of components can be suppressed, and short circuits near the electrode lead 26 can be prevented.

[0075] Furthermore, in this embodiment, by setting the width of the uncoated portion of the electrode sheet to be smaller than that of the coated portion, connection to the electrode lead 26 is facilitated. On the other hand, in the R region 40R of the electrode body 40, the ends of the electrode sheet 50 and the separator 60 are prone to positional misalignment. However, as described above, the uncoated portions 52B and 54B of the electrode sheet 50 are formed to include the base end position 40R1 of the R region 40R. Therefore, connection to the electrode lead 26 is facilitated, and short circuits can be effectively suppressed at locations of the coated portions 52A and 54A of the electrode sheet 50, which are prone to short circuits due to bending.

[0076] Furthermore, in this embodiment, since the electrode body 40 is sealed by the laminate film 22, the curvature of the R region 40R increases as the electrode sheet 50 is positioned toward the outer side relative to the sealed end portion 30 of the laminate film 22. Therefore, the closer to the outer side of the electrode body 40, the more likely the ends of the electrode sheet 50 and the separator 60 are to shift positions.

[0077] Therefore, in this embodiment, the length L3 of the width direction W of the uncoated portions 52B and 54B is increased as the electrode sheet 50 is disposed on the outer side relative to the sealed end portion of the laminate film 22. Therefore, the length L3 of the width direction W of the uncoated portions 52B and 54B is increased as the coated portions 52A and 54A of the electrode sheet 50 are more likely to be short-circuited due to bending (see FIG. Figure 6B ) is set longer, which can effectively prevent short circuits from occurring.

[0078] Furthermore, the battery cell 20 described in the above embodiment is manufactured by applying electrode active material to the current collectors (positive electrode current collector 521 and negative electrode current collector 541) and then removing the applied electrode active material from the end portions of the current collectors in the width direction W, i.e., the region including the base end position 40R1 of the R region 40R. This results in a battery cell 20 that minimizes component cost increases and prevents short circuits near the electrode leads 26. Furthermore, in this embodiment, since the electrode active material is removed from the end portions of the current collectors in the width direction W after application, the occurrence of "edge protrusion," where the thickness of the electrode active material layer increases, at the boundaries between the coated portions 52A, 54A and the uncoated portions 52B, 54B can be suppressed. By suppressing edge protrusion at the end surfaces of the electrode active material, leakage problems caused by localized compression of the separator during expansion and contraction during charge and discharge cycles can be suppressed.

[0079] The above describes one embodiment of the present invention, but the present invention is not limited thereto. For example, in the above embodiment, the length L3 of the uncoated portion in the width direction W is longer as the electrode sheet 50 is positioned on the outer side relative to the sealed end portion 30 of the laminate film 22, but the present invention is not limited thereto. The length L3 of the uncoated portion in the width direction W can be the same value for each electrode sheet. In this case, it is sufficient to set the uncoated portion of each electrode sheet 50 to correspond to the base end position 40R1 of the R region 40R of the outermost electrode sheet 50.

Claims

1. A battery cell comprising: The electrode body is composed of a positive electrode sheet and a negative electrode sheet stacked with a separator between them; a laminate film that seals the electrode body; and An electrode lead is connected to an uncoated portion of the sheet-shaped current collector on which an electrode active material is not coated at at least one end portion in the first width direction of the electrode sheet and is led out from the sealed end portion of the laminate film, characterized in that: The uncoated portion is formed at a base end position including an R-shaped region bent toward the sealed end portion at an end portion in the first width direction of the electrode sheet.

2. The battery cell according to claim 1, wherein: The length of the uncoated portion in a second width direction perpendicular to the first width direction is set to be shorter than the length of the coated portion in the electrode sheet where the electrode active material is coated on the current collector in the second width direction.

3. The battery cell according to claim 1 or 2, characterized in that: The electrode assembly is configured such that the length of the uncoated portion in the first width direction increases as the electrode sheet is arranged on the outer side relative to the sealed end portion.

Images