Battery cell

Abstract

The utility model provides a battery unit which can restrain cost rise caused by increase of the number of parts and can restrain short circuit near electrode leads. A battery cell (20) has a structure in which an electrode body (40) is sealed with a laminated film (22). A plurality of electrode sheets (50) included in an electrode body (40) have coated portions (52A, 54A) in which an electrode active material is coated on a sheet-shaped current collector and uncoated portions (52B, 54B) in which the electrode active material is not coated on the current collector, and the uncoated portions (52B, 54B) are provided on one side or the other side of the electrode body (40) in the width direction (W). And a plurality of separators (60) connected to one end of the electrode lead (26) led out from the sealed end portion (30) of the laminated film (22), the plurality of separators (60) gradually changing in the lamination direction in the length (L) of the end portion covering the uncoated portions (52B, 54B) of the electrode sheet (50) in one or the other in the width direction (W) of the electrode body (40).

Description

TECHNICAL FIELD

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

[0002] As the configuration of the electrode body housed in the inside of the battery unit, there is known a configuration in which a plurality of positive electrode sheets and a plurality of negative electrode sheets as a plurality of electrode sheets are laminated with a plurality of separators (for example, refer to Japanese Patent No. 7081192). The plurality of electrode sheets are formed on an uncoated portion of a sheet-shaped current collector on which an electrode active material is not coated, and the uncoated portion is connected to an electrode lead.

[0003] However, in the battery unit sealed with the laminated film for the electrode body, the end portions of the electrode sheets and the separators are bent in an R shape toward the sealing end portion of the laminated film. Therefore, this can cause the position of the end portion of the separator that ensures insulation between the electrode sheets to shift, and it is difficult to cover the surface of the electrode sheet with the separator up to the vicinity of the sealing end portion. In this way, at the portion where the electrode sheet is exposed from the separator, the coated portion of the electrode sheet bent in an R shape directly contacts the coated portion of the other electrode sheet, and short circuit can occur.

[0004] At the end portion where the electrode body is connected to the electrode lead, in order to prevent such short circuit, an insulating protective film can be attached to the end portion of the electrode sheet. However, the short circuit prevention measure using the protective film has a problem of cost increase due to an increase in the number of components. SUMMARY

[0005] The utility model takes the above fact into account, and aims to provide a battery unit that can suppress cost increase due to an increase in the number of components, and can suppress short circuit near the electrode lead.

[0006] The battery unit of the first aspect is a battery unit sealed with a laminated film for an electrode body in which a plurality of positive electrode sheets and a plurality of negative electrode sheets as a plurality of electrode sheets are laminated with a plurality of separators, wherein the plurality of electrode sheets have a coated portion on which an electrode active material is coated on a sheet-shaped current collector and an uncoated portion on which the electrode active material is not coated on the current collector, the uncoated portion is provided on one side or the other side in the width direction of the electrode body and is connected to one end of an electrode lead drawn from the sealing end portion of the laminated film, and the plurality of separators cover the end portion of the uncoated portion of the electrode sheet in one side or the other side in the width direction of the electrode body, and the length of the end portion gradually changes in the laminating direction.

[0007] In the battery cell of the first aspect, an electrode body in which a plurality of positive electrode sheets and a plurality of negative electrode sheets as a plurality of electrode sheets are stacked with a plurality of separators is provided. In addition, the electrode body is sealed with a laminated film. The plurality of electrode sheets has a coated portion in which an electrode active material is coated on a sheet-shaped current collector and an uncoated portion in which the electrode active material is not coated on the current collector. The uncoated portion is provided on one side or the other side in the width direction of the electrode body and is connected to one end of an electrode lead drawn from a sealed end portion of the laminated film.

[0008] However, in the battery cell sealed with the laminated film for the electrode body, the end portions of the electrode sheets and the separators are bent in an R shape toward the sealed end portion of the laminated film. Therefore, in a case where the sizes of the plurality of separators are uniform, the position of the end portion of the separator is shifted due to the bending, and it is difficult to cover the surface of the electrode sheet with the separator up to the vicinity of the sealed end portion. In addition, the size of the position shift differs depending on the arrangement position in the stacking direction of each separator. In this way, at a portion where the electrode sheet is exposed from the separator, the coated portion of the electrode sheet bent in the R shape directly contacts the coated portion of the other electrode sheet, and short circuiting can occur.

[0009] Here, according to the first aspect, the length of the end portion of the plurality of separators covering the uncoated portion of the electrode sheet in one side or the other side in the width direction of the electrode body gradually changes in the stacking direction. That is, the length of the end portion of the uncoated portion of the electrode body differs depending on the arrangement position in the stacking direction of each separator. Therefore, even in a case where the position of the end portion of the separator is shifted due to the R-shaped bending of the end portion of the electrode body, the length of the end portion can be gradually changed in correspondence with the curvature corresponding to the arrangement position in the stacking direction, and the separator can be arranged in the vicinity of the sealed end portion. Thus, in the vicinity of the sealed end portion, the electrode sheet is suppressed from being exposed from the separator, and the insulation between the electrode sheets becomes good without using a protective sheet for insulation. As a result, it is possible to suppress the increase in cost due to the increase in the number of components, and it is possible to suppress short circuiting in the vicinity of the electrode lead.

[0010] In the battery cell of the second aspect, the length of the end portion gradually changes in a manner that the position with respect to the sealed end portion of the laminated film becomes longer as it goes toward the outer layer side.

[0011] The greater the position shift of the end portion of the separator, the more the separator is arranged toward the outer layer side with respect to the sealed end portion of the laminated film. Here, in the battery cell of the second aspect, the length of the end portion of the separator covering the uncoated portion of the electrode sheet gradually changes in a manner that the position with respect to the sealed end portion of the laminated film becomes longer as it goes toward the outer layer side. Therefore, the greater the position shift of the end portion of the separator, the greater the length of the end portion, and thus the electrode sheet can be effectively suppressed from being exposed from the separator in the vicinity of the sealed end portion.

[0012] In the third type of battery cell, as viewed from the stacking direction in the first or second type, the end of the cell becomes a tapered shape that tapers toward the front end of the connection between the plurality of electrode sheets and the electrode leads.

[0013] In the battery cell according to the third method, the end of the separator covering the uncoated portion of the electrode sheets, when viewed from the stacking direction, becomes a tapered shape that tapers towards the front end of the connection between the multiple electrode sheets and the electrode leads. Therefore, the width of the electrode sheets decreases towards the connection with the electrode leads, effectively suppressing the exposure of the electrode sheets from the separator at locations where positional misalignment between the electrode sheets and the separator ends is likely to occur. Thus, short circuits can be suppressed, and the coating portion of the electrode sheets can be formed even near the electrode leads, improving the power generation efficiency of the battery cell.

[0014] As described above, in the battery cell of this invention, the cost increase caused by the increase in the number of components can be suppressed, and the short circuit near the electrode leads can be suppressed. Attached Figure Description

[0015] Figure 1 A schematic top view showing the main parts of a vehicle to which the battery pack involved in the embodiment is applied.

[0016] Figure 2 This is a schematic perspective view of the battery module involved in the implementation method.

[0017] Figure 3 A top view of the battery module in an embodiment where the top cover of the module housing has been removed.

[0018] Figure 4 This is a schematic diagram showing the battery cells housed in the battery module from the thickness direction.

[0019] Figure 5 This is a schematic diagram of a battery cell, representing the battery cell as a separate unit.

[0020] Figure 6A To be Figure 4 The enlarged side view is shown by partially cutting open one end of the battery cell in the width direction, as indicated by region P.

[0021] Figure 6B To illustrate along Figure 6A A cross-sectional view of the battery cell cut by the 6B-6B line. Detailed Implementation

[0022] The following is for reference Figures 1-6B One embodiment of this utility model will be described.

[0023] Figure 1A schematic plan view showing main portions of a vehicle 100 to which the battery pack 10 according to the embodiment is applied will be described. As shown in FIG. 1, the vehicle 100 is a battery electric vehicle (BEV) in which the battery pack 10 is mounted under a floor. Note that arrows UP, arrows FR, and arrows LH in each drawing represent an upper side in a vehicle up-down direction, a front side in a vehicle front-rear direction, and a left side in a vehicle width direction, respectively. In cases where the front-rear direction, the left-right direction, and the up-down direction are used for description, unless otherwise specified, the front-rear direction represents the front-rear direction of the vehicle, the left-right direction represents the left-right direction of the vehicle, and the up-down direction represents the up-down direction of the vehicle. Figure 1

[0024] As an example, the vehicle 100 according to the embodiment is provided with a DC / DC converter 102, an electric compressor 104, and a PTC (Positive Temperature Coefficient) heater 106 on a vehicle front side relative to the battery pack 10. In addition, a motor 108, a gear box 110, an inverter 112, and a charger 114 are provided on a vehicle rear side relative to the battery pack 10.

[0025] A direct current output from the battery pack 10 is supplied to the electric compressor 104, the PTC heater 106, the inverter 112, and the like after the voltage is adjusted by the DC / DC converter 102. In addition, by supplying electric power to the motor 108 via the inverter 112, the rear wheels rotate to cause the vehicle 100 to travel.

[0026] A charging port 116 is provided on a right side portion of a rear portion of the vehicle 100, and by connecting a charging plug of an external charging device, not shown, to the charging port 116, the battery pack 10 can be charged via the on-vehicle charger 114.

[0027] In addition, the configuration and the structure of each component constituting the vehicle 100 are not limited to those described above. For example, the vehicle 100 can be applied to a hybrid vehicle (HV) or a plug-in hybrid electric vehicle (PHEV) in which an engine is mounted. In addition, in the embodiment, the vehicle in which the motor 108 is mounted on the rear portion of the vehicle to drive the rear wheels is described, but the embodiment is not limited thereto. The vehicle in which the motor 108 is mounted on the front portion of the vehicle to drive the front wheels, or a vehicle in which a pair of motors 108 is mounted on the front and rear portions of the vehicle can be described. Furthermore, a vehicle in which each wheel has an in-wheel motor can be described.

[0028] ​Here, the battery pack 10 is configured to include a plurality of battery modules 11. In this embodiment, as an example, 10 battery modules 11 are provided. Specifically, five battery modules 11 are arranged in the vehicle front-rear direction on the right side of the vehicle 100, and five battery modules 11 are arranged in the vehicle front-rear direction on the left side of the vehicle 100. In addition, each of the battery modules 11 is electrically connected.

[0029] Figure 2 is a schematic perspective view of the battery module 11. As shown in Figure 2 , the battery module 11 has a module case 16 that constitutes an outer shell. The module case 16 is formed in a substantially rectangular parallelepiped shape with the vehicle width direction as the length direction. In addition, the module case 16 is formed of an aluminum alloy. The module case 16 is formed, for example, by joining aluminum die cast pieces at both end portions of an extruded material of an aluminum alloy using laser welding or the like.

[0030] A pair of voltage terminals 12 and a connector 14 are provided at both ends in the vehicle width direction of the battery module 11, respectively. The connector 14 is connected to a flexible printed board 21 described later. In addition, a bus bar not shown is welded at both ends in the vehicle width direction of the battery module 11.

[0031] The length MW in the vehicle width direction of the battery module 11 is, for example, 350 mm to 600 mm, the length ML in the vehicle front-rear direction is, for example, 150 mm to 250 mm, and the height MH in the vehicle up-down direction is, for example, 80 mm to 110 mm.

[0032] Figure 3 is a plan view of a state in which the upper cover of the battery module 11 is removed. As shown in Figure 3 , a plurality of battery cells 20 are housed inside the module case 16 in a state of being stacked with each other. Each of the battery cells 20 is housed in a posture in which the stacking direction is the thickness direction. In this embodiment, a stack is configured by arranging (stacking) 24 battery cells 20 in the vehicle front-rear direction and adhering them to each other.

[0033] In addition, in order to easily understand the explanation, in each of the drawings, Figures 3-6B , the direction indicated by the arrow W is set as the width direction of the battery cell 20, the direction indicated by the arrow H is set as the height direction (up-down direction) of the battery cell 20, and the direction indicated by the arrow D is set as the thickness direction of the battery cell 20.

[0034] The width direction of the stack film 22 described later coincides with the width direction W of the battery cell 20. The height direction of the stack film 22 coincides with the height direction H of the battery cell 20. The thickness direction of the stack film 22 coincides with the thickness direction D of the battery cell 20.

[0035] A flexible printed circuit (FPC) 21 is formed on the battery cell 20. The flexible printed circuit 21 is formed in a strip shape with the width of the vehicle as its length direction, and thermistors 23 are respectively provided at both ends of the flexible printed circuit 21. Thermistors 23 are not attached to the battery cell 20, but are formed by pressing the top cover of the battery module 11 toward the battery cell 20.

[0036] Additionally, one or more cushioning materials (not shown) are housed inside the module housing 16. For example, the cushioning material is a thin, elastically deformable plate-like component disposed between adjacent battery cells 20 whose thickness direction is the arrangement direction of the battery cells 20. In this embodiment, as an example, cushioning material is disposed at both ends and the central portion of the module housing 16 along its length.

[0037] Figure 4 This is a schematic diagram showing the battery cell viewed from the thickness direction D. (See diagram below.) Figure 4 As shown, the battery cell 20 is formed as a flat and elongated rectangular plate with the width direction W as the length direction, constituting a secondary battery capable of being charged and discharged.

[0038] The battery cell 20 has an electrode body 40 and a laminated film 22 sealing the electrode body 40. The electrode body 40 is connected to electrode leads 26 protruding in the width direction W at one and the other ends. The electrode leads 26 have a first electrode lead 26A connected to the positive electrode of the electrode body 40 in the width direction W and a second electrode lead 26B connected to the negative electrode of the electrode body 40 in the width direction W. The first electrode lead 26A and the second electrode lead 26B are formed as rectangular plates elongated in the width direction W. The laminated film 22 is embossed on at least one side in the thickness direction. By embossing, a concave receiving portion 221 (see reference) is formed on the side to house the electrode body 40. Figure 5 ).

[0039] Figure 5 This is a schematic diagram of a battery cell 20 as shown in disassembled form, depicting the state viewed from the height direction H when the battery cell 20 is disassembled. Figure 5 As shown, the laminated film 22 has a first laminated film 22A disposed on one side of the electrode body 40 in the thickness direction D and a second laminated film 22B disposed on the other side of the electrode body 40 in the thickness direction D. The first laminated film 22A and the second laminated film 22B overlap on both sides of the electrode body 40 in the thickness direction D and form a receiving space of the electrode body 40 by thermally fusing their outer peripheries together. Hereinafter, the portion where the outer peripheries of the first laminated film 22A and the second laminated film 22B are thermally fused together is referred to as the sealing end 30.

[0040] In the present embodiment, embossing is performed on one of the second laminated film 22B to form the accommodation portion 221. The laminated film 22 can adopt either a single-cup embossed structure in which embossing is performed at one location or a double-cup embossed structure in which embossing is performed at two locations, and in the present embodiment, the single-cup embossed structure in which the accommodation portion 221 having a draw depth of about 8 mm to 10 mm is formed on one of the second laminated film 22B is adopted.

[0041] On one side in the width direction W of the battery cell 20, one end of the first electrode lead 26A protrudes from the end portion of the laminated film 22 in the width direction W. On the other side in the width direction W of the battery cell 20, one end of the second electrode lead 26B protrudes from the end portion of the laminated film 22 in the width direction W.

[0042] On one side and the other side in the width direction W of the battery cell 20, the one end of the electrode lead 26 protruding from the laminated film 22 is welded to a busbar (not shown).

[0043] 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 more, the length CW2 of the region in which the electrode body is accommodated 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 more, the height CH of the battery cell 20 is, for example, 80 mm to 110 mm or 110 mm to 140 mm, 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, and 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.

[0044] The electrode body 40 is formed by alternately laminating a plurality of positive electrode sheets 52 and a plurality of negative electrode sheets 54 with a plurality of separators 60 interposed therebetween.

[0045] The positive electrode sheet 52 is, for example, formed by applying a positive electrode active material 522 to both surfaces of a sheet-shaped positive electrode current collector 521 formed of an aluminum foil. The positive electrode sheet 52 has a coated portion 52A in which the positive electrode active material 522 is applied to both surfaces of the positive electrode current collector 521, and an uncoated portion 52B in which the positive electrode active material 522 is not applied to the surface of the positive electrode current collector 521. The positive electrode active material 522 is a substance capable of intercalating and deintercalating ions, and can be composed of, for example, a lithium-nickel-based oxide, a lithium-cobalt-based oxide (e.g., LiCoO2, etc.), and a lithium-manganese-based oxide (e.g., LiMn2O4), etc., as long as it is a lithium-ion secondary battery.

[0046] The uncoated portion 52B is provided at the end portion on one side in the width direction W of the positive electrode sheet 52, and is formed as a protruding end portion that protrudes from the end portion on one side in the width direction of the separator 60. This uncoated portion 52B is integrated with the uncoated portions 52B of the other positive electrode sheets 52 at a prescribed position in the stacking direction (D) of the electrode body 40, and constitutes a positive electrode-side current collecting portion. In the present embodiment, the uncoated portions 52B of the plurality of positive electrode sheets 52 are integrated on the side of the first laminated film 22A, and constitute a positive electrode-side current collecting portion, and the first electrode lead 26A is disposed between this current collecting portion and the first laminated film 22A. Thus, the first electrode lead 26A is connected to the positive electrode of the electrode body 40. Figure 5

[0047] In addition, as shown in FIG. 6, the end portion region XP on the other side in the width direction W of the uncoated portion 52B becomes a tapered shape that narrows toward the front end of the first electrode lead 26A. Figure 6A

[0048] The negative electrode sheet 54 is, for example, formed by laminating a negative electrode active material 542 on both surfaces of a sheet-shaped negative electrode current collector 541 formed of a copper foil. The negative electrode sheet 54 has a coated portion 54A in which the negative electrode active material 542 is coated on both surfaces of the negative electrode current collector 541, and an uncoated portion 54B in which the negative electrode active material 542 is not coated on the surface of the negative electrode current collector 541. The negative electrode active material 542 is a substance that can intercalate and deintercalate ions, and can be composed of, for example, a carbon material, a fluorine resin (for example, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, or the like), polyvinyl acetate, or the like, as long as it is a lithium ion secondary battery.

[0049] As shown in FIG. 6, the uncoated portion 54B is provided at the end portion on the other side in the width direction W of the negative electrode sheet 54, and is formed as a protruding end portion that protrudes from the end portion on the other side in the width direction of the separator 60. This uncoated portion 54B is integrated with the uncoated portions 54B of the other negative electrode sheets 54 on the side of the first laminated film 22A, and constitutes a negative electrode-side current collecting portion. In the present embodiment, the uncoated portions 54B of the plurality of negative electrode sheets 54 are integrated on the side of the first laminated film 22A, and constitute a negative electrode-side current collecting portion, and the second electrode lead 26B is disposed between this current collecting portion and the first laminated film 22A. Thus, the second electrode lead 26B is connected to the negative electrode of the electrode body 40. Figure 5 In addition, although not shown, like the uncoated portion 52B of the positive electrode sheet 52, the end portion region XP on the other side in the width direction W of the uncoated portion 54B becomes a tapered shape that narrows toward the front end of the second electrode lead 26B.

[0050]

[0051] ​​​The separator 60 is an insulating layer that maintains the spacing of the positive electrode sheet 52 and the negative electrode sheet 54 to prevent the occurrence of a contact short circuit, and holds the nonaqueous electrolyte solution. The separator 60 is composed of, for example, a porous resin flat plate. In the present embodiment, the battery cell 20 has a plurality of separators 60 cut out in a sheet shape, and one separator 60 is disposed between the positive electrode sheet 52 and the negative electrode sheet 54.

[0052] The plurality of separators 60 has a plurality of first separators 61 disposed so as to contact the positive electrode sheet 52 on the inner layer side toward the sealing end portion 30, and a plurality of second separators 62 disposed so as to contact the negative electrode sheet 54 on the inner layer side toward the sealing end portion 30. The plurality of first separators 61 is disposed so as to cover the end portion of the uncoated portion 52B of the positive electrode sheet 52 on one side in the width direction W. In addition, the plurality of second separators 62 is disposed so as to cover the end portion of the uncoated portion 54B of the negative electrode sheet 54 on the other side in the width direction W.

[0053] Here, the length L (L1 to L6) of the end portion of the uncoated portion of the electrode sheet covered by the first separator 61 and the second separator 62 on one side or the other side in the width direction W gradually changes in the stacking direction. That is, the length L1, L2, L3 of the uncoated portion 52B of the positive electrode sheet 52 covered by the plurality of first separators 61 on one side in the width direction W gradually changes in the stacking direction. In addition, the length L4, L5, L6 of the uncoated portion 54B of the negative electrode sheet 54 covered by the plurality of second separators 62 on the other side in the width direction W gradually changes in the stacking direction.

[0054] Specifically, in the present embodiment, the length L of the end portion of the separator 60 gradually changes in a manner that becomes longer toward the outer layer side with respect to the position of the sealing end portion 30 of the laminated film 22.

[0055] Figure 6B is an enlarged view of the cut surface of the end portion of the battery cell 20 on one side in the width direction W. As shown in Figure 6B In the end portion of the battery cell 20 on one side in the width direction W, the end portion of the positive electrode sheet 52 and the separator 60 is curved in an R shape toward the sealing end portion 30 of the laminated film 22. The curvature of the end portion of the separator 60 in the width direction W differs depending on the stacking position of each separator 60, and becomes larger as it is closer to the outer layer side with respect to the sealing end portion 30. Therefore, if the length L of the end portion of the separator 60 is made uniform, the position of the end portion of the separator 60 on the outer layer side shifts more toward the inner side in the width direction W, and thus it is difficult to cover the surface of the positive electrode sheet 52 with the separator 60 up to the vicinity of the sealing end portion 30 of the laminated film 22.

[0056] In contrast, in the present embodiment, the length L of the end portion of the separator 60 gradually changes in a manner that becomes longer toward the outer layer side with respect to the position of the sealed end portion 30 of the laminated film 22. Therefore, it is possible to cover the surface of the positive electrode sheet 52 on the inner layer side with the separator 60 up to the vicinity of the sealed end portion 30.

[0057] In addition, the present application is not limited to the above-described structure, and for example, the length L of the end portion of the separator 60 can be gradually changed in a manner that becomes longer toward the inner layer side with respect to the position of the sealed end portion 30 of the laminated film 22. In this case, the end portion in the width direction W of each separator 60 can also be configured to cover the uncoated portion of the electrode sheet arranged on the outer layer side with respect to the separator 60. However, by gradually changing the length L of the end portion of the separator 60 in a manner that becomes longer toward the outer layer side with respect to the position of the sealed end portion 30 of the laminated film 22, it is possible to arrange the outermost separator 60 to the vicinity of the sealed end portion 30 inside the battery cell 20, and thus it is possible to cover the entire surface of the electrode body 40 well.

[0058] As described above, in the battery cell 20 according to the present embodiment, the electrode body 40 in which a plurality of positive electrode sheets 52 and a plurality of negative electrode sheets 54 as a plurality of electrode sheets 50 are laminated with a plurality of separators 60 interposed therebetween is provided. In addition, in the battery cell 20, the electrode body 40 is sealed with the laminated film 22. The plurality of electrode sheets 50 has a coated portion 52A, 54A in which an electrode active material is coated on a sheet-shaped current collector, and an uncoated portion 52B, 54B in which the electrode active material is not coated on the current collector. The uncoated portion 52A, 54B is provided on one or the other of the width direction W of the electrode body 40, and is connected to one end of the electrode lead 26 drawn from the sealed end portion 30 of the laminated film 22.

[0059] However, in the battery cell 20 in which the electrode body 40 is sealed with the laminated film 22, the end portions of the electrode sheet 50 and the separator 60 are bent in an R shape toward the sealed end portion 30 of the laminated film 22. Therefore, in the case where the dimensions of the plurality of separators 60 are uniform, the position of the end portion of the separator 60 is shifted due to the bending, and it is difficult to cover the surface of the electrode sheet 50 with the separator 60 up to the vicinity of the sealed end portion 30. In addition, the size of the position shift differs depending on the arrangement position in the lamination direction of each separator 60. In this way, among the portions in which the electrode sheet 50 is exposed from the separator 60, the coated portion 52A, 54A of the electrode sheet 50 bent in an R shape directly contacts the coated portion 52A, 54A of the other electrode sheet 50, and short circuiting can occur.

[0060] Here, according to the present embodiment, the length L of the end portion of the separator 60 covering the uncoated portion 52B, 54B of the electrode sheet 50 gradually changes in the stacking direction in one or the other of the width direction W of the electrode body 40. That is, the length L of the end portion of the uncoated portion 52B, 54B of the electrode body 40 covered by each separator 60 differs depending on the arrangement position in the stacking direction. Therefore, even in the case where the position of the end portion of the separator 60 shifts due to the R-shaped bending of the end portion of the electrode body 40, the length L of the end portion is gradually changed in accordance with the curvature corresponding to the arrangement position in the stacking direction, and the separator 60 is arranged in the vicinity of the sealed end portion 30. Thus, in the vicinity of the sealed end portion 30, the electrode sheet 50 is prevented from being exposed from the separator 60, and the insulation between the electrode sheets 50 is good without using other members such as a protective sheet for insulation. As a result, it is possible to suppress the increase in cost due to the increase in the number of components, and to suppress the occurrence of short circuit in the vicinity of the electrode lead 26.

[0061] In addition, the separator arranged on the outer layer side with respect to the sealed end portion 30 of the laminated film 22 has a larger shift in the position of the end portion. Here, in the battery cell 20 of the present embodiment, the length L of the end portion of the separator 60 covering the uncoated portion 52B, 54B of the electrode sheet 50 gradually changes in a manner such that the position with respect to the sealed end portion 30 of the laminated film 22 becomes longer toward the outer layer side. Therefore, the larger the shift in the position of the end portion of the separator 60, the larger the length L of the end portion, and even in the region of the outermost layer of the electrode body 40, the electrode sheet 50 is effectively prevented from being exposed from the separator 60 in the vicinity of the sealed end portion 30.

[0062] In addition, in the present embodiment, the end portion of the separator 60 covering the uncoated portion 52B, 54B of the electrode sheet 50 becomes a tapered shape that becomes narrower toward the front end of the connection portion of the electrode sheet 50 and the electrode lead 26 when viewed in the stacking direction. Therefore, the width (width in the height direction H in the case of the electrode sheet 50) of the electrode sheet 50 becomes smaller toward the connection portion with the electrode lead 26, and the electrode sheet 50 is effectively prevented from being exposed from the separator 60 at the portion where the position of the end portion of the electrode sheet 50 and the separator 60 is likely to shift. Therefore, the occurrence of short circuit is suppressed, and the coated portion 52A, 54A of the electrode sheet 50 can be formed up to the vicinity of the electrode lead 26, and the power generation efficiency of the battery cell 20 can be improved. Figure 6A In addition, in the present embodiment, the end portion of the separator 60 covering the uncoated portion 52B, 54B of the electrode sheet 50 becomes a tapered shape that becomes narrower toward the front end of the connection portion of the electrode sheet 50 and the electrode lead 26 when viewed in the stacking direction. Therefore, the width (width in the height direction H in the case of the electrode sheet 50) of the electrode sheet 50 becomes smaller toward the connection portion with the electrode lead 26, and the electrode sheet 50 is effectively prevented from being exposed from the separator 60 at the portion where the position of the end portion of the electrode sheet 50 and the separator 60 is likely to shift. Therefore, the occurrence of short circuit is suppressed, and the coated portion 52A, 54A of the electrode sheet 50 can be formed up to the vicinity of the electrode lead 26, and the power generation efficiency of the battery cell 20 can be improved.

Claims

1. A battery cell that is a battery cell sealed with a laminated film of an electrode body in which a plurality of positive electrode sheets and a plurality of negative electrode sheets as a plurality of electrode sheets are laminated with a plurality of separators, characterized in that, the plurality of electrode sheets have a coated portion in which an electrode active material is coated on a sheet-shaped current collector, and an uncoated portion in which the electrode active material is not coated on the current collector, the uncoated portion is provided on one side or the other side in a width direction of the electrode body, and is connected to one end of an electrode lead drawn from a sealed end portion of the laminated film, the plurality of separators cover end portions of the uncoated portions of the electrode sheets in one side or the other side in the width direction of the electrode body, and a length of the end portions gradually changes in a lamination direction.

2. The battery cell of claim 1, wherein, the length of the end portions gradually changes in a manner that the position with respect to the sealed end portion of the laminated film becomes longer toward an outer layer side.

3. The battery cell according to claim 1 or 2, characterized in that, the end portions become a tapered shape that becomes narrower toward a front end of a connection portion of the plurality of electrode sheets and the electrode lead, as viewed from the lamination direction.

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