Battery cell

Abstract

To provide a battery cell capable of preventing short circuits near electrode leads while suppressing the increase in costs due to the increase in the number of parts.SOLUTION: A battery cell 20 has a structure in which an electrode body 40 is sealed with a laminate film 22. Multiple electrode sheets 50 included in the electrode body 40 has coated parts 52A, 54A, where a sheet-shaped current collector is coated with an electrode active material, and uncoated parts 52B, 65B, where the current collector is not coated with the electrode active material, and which are connected to one end of an electrode lead 26 that is provided on one side or the other side of the width direction W of the uncoated parts 52B, 54B and the electrode body 40 and pulled out from the sealed end 30 of the laminate film 22. In multiple separators 60, on one side or the other side of the width direction W of the electrode body 40, the length L of the end of the electrode sheet 50 covering the uncoated parts 52B and 54B is gradually changed in the stacking direction.SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] As a structure of an electrode body housed inside an electronic cell, a structure in which a plurality of positive electrode sheets and a plurality of negative electrode sheets as a plurality of electrode sheets are laminated via a plurality of separators is known (see, for example, Patent Document 1). In the plurality of electrode sheets, an uncoated portion where the electrode active material is not coated is formed on a sheet-shaped current collector, and the uncoated portion is connected to an electrode lead.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a battery cell in which the electrode body is sealed with a laminate film, the ends of the electrode sheet and the separator are curved in an R shape toward the sealing end of the laminate film. For this reason, displacement of the position of the end of the separator that secures insulation between the electrode sheets occurs, and it becomes difficult to cover the surface of the electrode sheet with the separator up to the vicinity of the sealing end. Thus, at a site where the electrode sheet is exposed from the separator, there is a risk of short circuit due to direct contact between the coated portion of the electrode sheet curved in an R shape and the coated portion of another electrode sheet.

[0005] At the end where the electrode body and the electrode lead are connected, in order to prevent such a short circuit, an insulating protective film is pasted on the end of the electrode sheet. However, the measure of preventing short circuit by the protective film has been a problem of cost increase due to an increase in the number of components.

[0006] In view of the above facts, an object of the present invention is to obtain a battery cell that can suppress an increase in cost due to an increase in the number of members and can suppress the occurrence of a short circuit in the vicinity of an electrode lead.

Means for Solving the Problems

[0007] A battery cell according to a first aspect is a battery cell in which an electrode body formed by laminating a plurality of positive electrode sheets and a plurality of negative electrode sheets as a plurality of electrode sheets via a plurality of separators is sealed with a laminate film, wherein 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 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 sealing end portion of the laminate film, and in the plurality of separators, the length of an end portion covering the uncoated portion of the electrode sheet is gradually changed in the stacking direction on one or the other side in the width direction of the electrode body.

[0008] The battery cell according to the first aspect includes an electrode body formed by laminating a plurality of positive electrode sheets and a plurality of negative electrode sheets as a plurality of electrode sheets via a plurality of separators. Further, in the battery cell, the electrode body is sealed with a laminate film. 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. This uncoated portion is provided on one 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 sealing end portion of the laminate film.

[0009] By the way, in a battery cell in which the electrode body is sealed with a laminate film, the ends of the electrode sheet and the separator are curved in an R shape toward the sealed end of the laminate film. For this reason, when the sizes of the plurality of separators are uniform, displacement of the ends of the separator occurs due to the curvature, and it becomes difficult to cover the surface of the electrode sheet with the separator up to the vicinity of the sealed end. Also, the amount of displacement varies depending on the arrangement position of each separator in the stacking direction. In this way, at the site where the electrode sheet is exposed from the separator, there is a risk of short circuit due to the coated portion of the R-shaped curved electrode sheet coming into direct contact with the coated portions of other electrode sheets.

[0010] Here, according to the first aspect, in one or the other of the width directions of the electrode body, the length of the end portion covering the uncoated portion of the electrode sheet is gradually changed in the stacking direction among the plurality of the separators. That is, each separator has a different length of the end portion covering the uncoated portion of the electrode body according to the arrangement position in the stacking direction. Therefore, even when displacement of the end portion of the separator occurs due to the R-shaped curvature of the end portion of the electrode body, the length of the end portion can be gradually changed according to the curvature corresponding to the arrangement position in the stacking direction, and the separator can be arranged up to the vicinity of the sealed end. Thereby, exposure of the electrode sheet from the separator is suppressed in the vicinity of the sealed end, and insulation between the electrode sheets is improved without using a protective sheet for insulation. As a result, it is possible to suppress the occurrence of a short circuit in the vicinity of the electrode lead while suppressing an increase in cost due to an increase in the number of components.

[0011] The battery cell according to the second aspect is, in the first aspect, such that the length of the end portion is gradually changed so as to become longer toward the outer layer side with respect to the position of the sealed end of the laminate film.

[0012] The displacement of the end of the separator increases as the separator is disposed closer to the outer layer side with respect to the sealed end of the laminate film. Here, in the battery cell of the second aspect, the length of the end of the separator covering the non-coated portion of the electrode sheet is gradually changed so as to increase as it goes toward the outer layer side with respect to the position of the sealed end of the laminate film. For this reason, the length of the end of the separator disposed at a position where the displacement of the end of the separator is large becomes larger, and exposure of the electrode sheet from the separator is effectively suppressed in the vicinity of the sealed end.

[0013] In the battery cell of the third aspect, in the first aspect or the second aspect, the end portion has a tapered shape that tapers toward the connection portion of the plurality of electrode sheets and the electrode lead when viewed from the stacking direction.

[0014] In the battery cell according to the third aspect, the end of the separator covering the non-coated portion of the electrode sheet has a tapered shape that tapers toward the connection portion of the plurality of electrode sheets and the electrode lead when viewed from the stacking direction. For this reason, the width of the electrode sheet becomes smaller toward the connection portion with the electrode lead, and exposure of the electrode sheet from the separator can be effectively suppressed at a site where displacement of the end portions of the electrode sheet and the separator is likely to occur. Therefore, while suppressing the occurrence of a short circuit, it becomes possible to form the coated portion of the electrode sheet up to the vicinity of the electrode lead, and the power generation efficiency of the battery cell can be increased.

Advantages of the Invention

[0015] As described above, in the battery cell according to the present invention, it is possible to suppress the occurrence of a short circuit in the vicinity of the electrode lead while suppressing an increase in cost due to an increase in the number of components.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0017] Hereinafter, with reference to FIGS. 1 to 6(B), an embodiment of the present invention will be described.

[0018] (Overall Configuration of Vehicle 100) FIG. 1 is a schematic plan view showing a main part of a vehicle 100 to which a battery pack 10 according to the embodiment is applied. As shown in FIG. 1, the vehicle 100 is a battery electric vehicle (BEV) in which the battery pack 10 is mounted under the floor. In addition, the arrows UP, FR and LH in each figure indicate the upper side in the vehicle up-down direction, the front side in the vehicle front-rear direction, and the left side in the vehicle width direction, respectively. When explaining using the front-rear, left-right, and up-down directions of the vehicle, unless otherwise specified, the front and rear in the vehicle front-rear direction, the left and right in the vehicle width direction, and the up and down in the vehicle up-down direction are shown.

[0019] As an example, in the vehicle 100 of the present embodiment, a DC / DC converter 102, an electric compressor 104, and a PTC (Positive Temperature Coefficient) heater 106 are arranged on the vehicle front side of the battery pack 10. Further, on the vehicle rear side of the battery pack 10, a motor 108, a gearbox 110, an inverter 112, and a charger 114 are arranged.

[0020] The DC current output from the battery pack 10 is supplied to the electric compressor 104, the PTC heater 106, the inverter 112, etc. after the voltage is adjusted by the DC / DC converter 102. Also, by supplying power to the motor 108 via the inverter 112, the rear wheels rotate to make the vehicle 100 travel.

[0021] A charging port 116 is provided on the right side at the rear of the vehicle 100. By connecting a charging plug of an external charging facility (not shown) to the charging port 116, power can be stored in the battery pack 10 via the in-vehicle charger 114.

[0022] Note that the arrangement and structure of each component constituting the vehicle 100 are not limited to the above-described configuration. For example, it may be applied to a hybrid vehicle (HV) equipped with an engine or a plug-in hybrid electric vehicle (PHEV). Also, in this embodiment, the vehicle is a rear-wheel drive vehicle with the motor 108 mounted at the rear of the vehicle, but it is not limited to this. The vehicle may be a front-wheel drive vehicle with the 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 equipped with in-wheel motors on each wheel may also be used.

[0023] 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, 5 battery modules 11 are arranged in the longitudinal direction of the vehicle on the right side of the vehicle 100, and 5 battery modules 11 are arranged in the longitudinal direction of the vehicle on the left side of the vehicle 100. Also, each of the battery modules 11 is electrically connected.

[0024] Figure 2 is a schematic perspective view of the battery module 11. As shown in Figure 2, the battery module 11 includes a module case 16 that forms an outer shell. The module case 16 is formed in a substantially rectangular parallelepiped shape with the vehicle width direction as the longitudinal direction. Further, the module case 16 is formed of an aluminum alloy. For example, the module case 16 is formed by joining aluminum die-castings to both ends of an extruded material of an aluminum alloy by laser welding or the like.

[0025] A pair of voltage terminals 12 and connectors 14 are provided at both ends of the battery module 11 in the vehicle width direction, respectively. A flexible printed circuit board 21 described later is connected to the connector 14. Further, bus bars (not shown) are welded to both ends of the battery module 11 in the vehicle width direction.

[0026] The length MW of the battery module 11 in the vehicle width direction is, for example, 350 mm to 600 mm, the length ML in the vehicle longitudinal direction is, for example, 150 mm to 250 mm, and the height MH in the vehicle vertical direction is, for example, 80 mm to 110 mm.

[0027] Figure 3 is a plan view of the battery module 11 with the upper lid removed. As shown in Figure 3, a plurality of battery cells 20 stacked on each other are housed inside the module case 16. Each battery cell 20 is housed in a posture with the stacking direction as the thickness direction. In the present embodiment, 24 battery cells 20 are arranged (stacked) in the vehicle longitudinal direction and adhered to each other to form a stacked body.

[0028] For easy understanding of the description, in each of Figures 3 to 6(B), the direction indicated by the arrow W is defined as the width direction of the battery cell 20, the direction indicated by the arrow H is defined as the height direction (vertical direction) of the battery cell 20, and the direction indicated by the arrow D is defined as the thickness direction of the battery cell 20. Note that the width direction W is an example of the "first width direction", and the height direction H orthogonal to the width direction W is an example of the "second width direction". 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.

[0029] On the battery cell 20, a flexible printed circuit (FPC) 21 is arranged. The flexible printed circuit board 21 is formed in a strip shape with the vehicle width direction as the longitudinal direction, and thermistors 23 are provided at both ends of the flexible printed circuit board 21, respectively. The thermistor 23 is not adhered to the battery cell 20 and is configured to be pressed toward the battery cell 20 side by the upper lid of the battery module 11.

[0030] Also, one or more cushioning materials (not shown) are accommodated inside the module case 16. For example, the cushioning material is an elastically deformable thin plate-like member and is arranged between adjacent battery cells 20 with the arrangement direction of the battery cells 20 as the thickness direction. In this embodiment, as an example, cushioning materials are arranged at both longitudinal ends and the central portion in the longitudinal direction of the module case 16, respectively.

[0031] FIG. 4 is a schematic view of the battery cell seen from the thickness direction D. As shown in FIG. 4, 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 capable of charging and discharging.

[0032] The battery cell 20 has an electrode body 40 and a laminate film 22 that seals the electrode body 40. The electrode body 40 is connected to electrode leads 26 that project in the width direction W at one and the other ends in the width direction W. The electrode leads 26 include a first electrode lead 26A that is connected to the positive electrode of the electrode body 40 on one side in the width direction W, and a second electrode lead 26B that is connected to the negative electrode of the electrode body 40 on the other side in the width direction W. The first electrode lead 26A and the second electrode lead 26B are formed in a rectangular plate shape that is long in the width direction W. The laminate film 22 is embossed on at least one side in the thickness direction. By applying the embossing process, a concave accommodating portion 221 (see FIG. 5) in which the electrode body 40 is accommodated is formed on the side surface.

[0033] FIG. 5 is a schematic view of the battery cell 20 shown in an exploded state, showing the state as viewed from the height direction H in the exploded state of the battery cell 20. As shown in FIG. 5, the laminate film 22 has a first laminate film 22A disposed on one side in the thickness direction D of the electrode body 40 and a second laminate film 22B disposed on the other side in the thickness direction D of the electrode body 40. The first laminate film 22A and the second laminate film 22B are overlapped in the thickness direction D on both sides of the electrode body 40, and the outer peripheral portions are heat-sealed to form an accommodation space for the electrode body 40. Hereinafter, the heat-sealed portion between the outer peripheral portions of the first laminate film 22A and the second laminate film 22B is referred to as a sealing end portion 30.

[0034] In the present embodiment, the second laminate film 22B is embossed on one side, and the accommodating portion 221 is formed. The laminate film 22 can adopt both a single cup embossing structure with one embossing and a double cup embossing structure with two embossings. However, in the present embodiment, a single cup embossing structure in which an accommodating portion 221 having a drawing depth of about 8 mm to 10 mm is formed on one side of the second laminate film 22B is adopted.

[0035] On one side of the width direction W of the battery cell 20, one end of the first electrode lead 26A protrudes in the width direction W from the end of the laminate film 22. On the other side of the width direction W of the battery cell 20, one end of the second electrode lead 26B protrudes in the width direction W from the end of the laminate film 22.

[0036] On one side and the other side of the width direction W of the battery cell 20, one end of the electrode lead 26 protruding from the laminate film 22 is welded to a bus bar (not shown).

[0037] 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 to 900 mm, 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 to 900 mm, 1000 mm or more. The height CH of the battery cell 20 is, for example, 80 mm to 110 mm, 110 mm to 140 mm. Further, the thickness of the battery cell 20 is 5.0 mm to 7.0 mm, 7.0 mm to 9.0 mm, 9.0 mm to 11.0 mm, and the height TH of the electrode lead (terminal) 26 is 40 mm to 50 mm, 50 mm to 60 mm, 60 mm to 70 mm.

[0038] (Electrode body) The electrode body 40 has a plurality of positive electrode sheets 52 and a plurality of negative electrode sheets 54 as a plurality of electrode sheets 50 alternately laminated via a plurality of separators 60.

[0039] (Positive electrode sheet) The positive electrode sheet 52 is, for example, a sheet-like positive electrode current collector 521 made of aluminum foil with a positive electrode active material 522 coated on both sides thereof. The positive electrode sheet 52 has a coated portion 52A where the positive electrode active material 522 is coated on both sides 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. The positive electrode active material 522 is a material capable of storing and releasing ions. In the case of a lithium-ion secondary battery, for example, it can be composed of a lithium nickel-based oxide, a lithium cobalt-based oxide (e.g., LiCoO2, etc.), a lithium manganese-based oxide (e.g., LiMn2O4), etc.

[0040] The uncoated portion 52B is provided at one end in the width direction W of the positive electrode sheet 52 and is a protruding end portion that protrudes from one end in the width direction of the separator 60. This uncoated portion 52B is integrated with the uncoated portions 52B of other positive electrode sheets 52 at a predetermined position in the stacking direction (thickness direction D in FIG. 5) of the electrode body 40 to form a current collecting portion on the positive electrode side. In the present embodiment, the uncoated portions 52B of the plurality of positive electrode sheets 52 are integrated on the side of the first laminate film 22A to form a current collecting portion on the positive electrode side, and a first electrode lead 26A is disposed between the current collecting portion and the first laminate film 22A. Thereby, the first electrode lead 26A is connected to the positive electrode of the electrode body 40. Also, as shown in FIG. 6(A), one end region XP in the width direction W of the uncoated portion 52B has a tapered shape that tapers toward the first electrode lead 26A.

[0041] (Negative electrode sheet) The negative electrode sheet 54 is, for example, a sheet-like negative electrode current collector 541 made of copper foil with a negative electrode active material 542 laminated on both sides thereof. The negative electrode sheet 54 has a coated portion 54A where the negative electrode active material 542 is coated on both sides 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. The negative electrode active material is a material capable of storing and releasing ions. In the case of a lithium-ion secondary battery, for example, it can be composed of a carbon material, a fluororesin (e.g., polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, etc.), polyvinyl acetate, etc.

[0042] As shown in FIG. 5, the uncoated portion 54B is provided at the other end in the width direction W of the negative electrode sheet 54, and is a protruding end portion that protrudes from the other end in the width direction of the separator 60. This uncoated portion 54B is integrated on the side of the first laminate film 22A together with the uncoated portions 54B of the other negative electrode sheets 54, and constitutes a current collecting portion on the negative electrode side. In the present embodiment, the uncoated portions 54B of the plurality of negative electrode sheets 54 are integrated on the side of the first laminate film 22A to constitute a current collecting portion on the negative electrode side, and the second electrode lead 26B is disposed between the current collecting portion and the first laminate film 22A. Thereby, the second electrode lead 26B is connected to the negative electrode of the electrode body 40. Also, although not shown, similar to the uncoated portion 52B of the positive electrode sheet 52, the other end region XP in the width direction W of the uncoated portion 54B has a tapered shape that tapers toward the second electrode lead 26B.

[0043] (Separator) The separator 60 is an insulating layer that maintains the interval between the positive electrode sheet 52 and the negative electrode sheet 54 to prevent the occurrence of a short circuit due to contact, and holds the non-aqueous electrolyte. 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.

[0044] The plurality of separators 60 include a plurality of first separators 61 disposed such that the inner layer side toward the sealing end portion 30 is in contact with the positive electrode sheet 52, and a plurality of second separators 62 disposed such that the inner layer side toward the sealing end portion 30 is in contact with the negative electrode sheet 54. One end in the width direction W of the plurality of first separators 61 is disposed so as to cover the uncoated portion 52B of the positive electrode sheet 52. Also, one end in the width direction W of the plurality of second separators 62 is disposed so as to cover the uncoated portion 54B of the negative electrode sheet 54.

[0045] Here, for the first separator 61 and the second separator 62, the length L of the end portion covering the non-coated portion of the electrode sheet in one or the other of the width directions W is gradually changed in the stacking direction. That is, for the plurality of first separators 61, in one of the width directions W, the lengths L1, L2, L3 covering the non-coated portion 52B of the positive electrode sheet 52 are gradually changed in the stacking direction. Also, for the plurality of second separators 62, in the other of the width directions W, the lengths L4, L5, L6 covering the non-coated portion 54B of the negative electrode sheet 54 are gradually changed in the stacking direction.

[0046] Specifically, in the present embodiment, the length L of the end portion of the separator 60 is gradually changed so as to become longer as it goes toward the outer layer side with respect to the position of the sealing end portion 30 of the laminate film 22.

[0047] FIG. 6(B) is a schematic view showing an enlarged cross section of one end portion in the width direction W of the battery cell 20. As shown in FIG. 6(B), at one end portion in the width direction W of the battery cell 20, the end portions of the positive electrode sheet 52 and the separator 60 are curved in an R shape toward the sealing end portion 30 of the laminate film 22. The curvature of the end portion of the separator 60 in the width direction W varies depending on the stacking position of each separator 60, and becomes larger as it is on the outer layer side with respect to the sealing end portion 30. For this reason, 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 is shifted more toward the inner side in the width direction W, so that it becomes 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 laminate film 22.

[0048] On the other hand, in the present embodiment, the length L of the end portion of the separator 60 is gradually changed so as to become longer as it goes toward the outer layer side with respect to the position of the sealing end portion 30 of the laminate film 22. For this reason, 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 sealing end portion 30.

[0049] Note that the present invention is not limited to the above configuration. For example, the length L of the end portion of the separator 60 may be gradually changed so as to become longer as it goes toward the inner layer side with respect to the position of the sealing end portion 30 of the laminate film 22. In this case, the end portions in the width direction W of each separator 60 may be configured to cover the uncoated portions of the electrode sheets disposed 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 so as to become longer as it goes toward the outer layer side with respect to the position of the sealing end portion 30 of the laminate film 22, the outermost separator 60 can be extended to the vicinity of the sealing end portion 30 in the battery cell 20, so that it is possible to satisfactorily cover the entire surface of the electrode body 40.

[0050] (Operation and Effect) As described above, in the battery cell 20 according to the present embodiment, an electrode body 40 is provided 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 via a plurality of separators 60. Further, in the battery cell 20, the electrode body 40 is sealed with a laminate film 22. The plurality of electrode sheets 50 have coated portions 52A and 54A in which an electrode active material is coated on a sheet-like current collector, and uncoated portions 52B and 54B in which the electrode active material is not coated on the current collector. The uncoated portions 52A and 54B are provided on one or the other side in the width direction W of the electrode body 40 and are connected to one end of an electrode lead 26 drawn out from the sealing end portion 30 of the laminate film 22.

[0051] Incidentally, in the battery cell 20 in which the electrode body 40 is sealed with the laminate film 22, the ends of the electrode sheet 50 and the separator 60 are curved in an R shape toward the sealing end 30 of the laminate film 22. For this reason, when the sizes of the plurality of separators 60 are uniform, displacement of the ends of the separator 60 occurs due to the curvature, and it becomes difficult to cover the surface of the electrode sheet 50 with the separator 60 up to the vicinity of the sealing end 30. Further, the magnitude of the displacement varies depending on the arrangement position of each separator 60 in the stacking direction. In this way, at the site where the electrode sheet 50 is exposed from the separator 60, there is a risk of short circuit due to the coating portions 52A, 54A of the R-shaped curved electrode sheet 50 coming into direct contact with the coating portions 52A, 54A of the other electrode sheets 50.

[0052] Here, according to the present embodiment, in one or the other of the width directions W of the electrode body 40, the length L of the end portion covering the uncoated portions 52B, 54B of the electrode sheet 50 of the plurality of separators 60 is gradually changed in the stacking direction. That is, for each separator 60, the length L of the end portion covering the uncoated portions 52B, 54B of the electrode body 40 is different depending on the arrangement position in the stacking direction. Therefore, even when displacement of the end portion of the separator 60 occurs due to the R-shaped curvature 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 can be arranged up to the vicinity of the sealing end 30. As a result, exposure of the electrode sheet 50 from the separator 60 is suppressed in the vicinity of the sealing end 30, and insulation between the electrode sheets 50 is improved without using another member such as a protective sheet for insulation. As a result, it is possible to suppress an increase in cost due to an increase in the number of members and to suppress the occurrence of a short circuit in the vicinity of the electrode lead 26.

[0053] In addition, the displacement of the end portion of the separator 60 increases as the separator 60 is disposed on the outer layer side with respect to the sealed end portion 30 of the laminate film 22. Here, in the battery cell 20 of the present embodiment, the length L of the end portion of the separator 60 that covers the non-coated portions 52B and 54B of the electrode sheet 50 gradually changes so as to increase as it goes toward the outer layer side with respect to the position of the sealed end portion 30 of the laminate film 22. For this reason, the length L of the end portion of the separator 60 is larger for the separator 60 disposed at a position where the displacement of the end portion of the separator 60 is large, and even in the outermost layer region of the electrode body 40, near the sealed end portion 30, the electrode sheet 50 is effectively prevented from being exposed from the separator 60.

[0054] Further, in the present embodiment, the end portion of the separator 60 that covers the non-coated portions 52B and 54B of the electrode sheet 50 has a tapered shape that tapers toward the connection portion between the plurality of electrode sheets 50 and the electrode lead 26 when viewed in the stacking direction. For this reason, the width of the electrode sheet 50 (the width in the height direction H in FIG. 6(A) and the like) becomes smaller toward the connection portion with the electrode lead 26, and at a portion where displacement of the end portions of the electrode sheet 50 and the separator 60 is likely to occur, it is possible to effectively prevent the electrode sheet 50 from being exposed from the separator 60. For this reason, it is possible to form the coated portions 52A and 54A of the electrode sheet 50 up to the vicinity of the electrode lead 26 while suppressing the occurrence of a short circuit, and it is possible to improve the power generation efficiency of the battery cell 20.

Explanation of Reference Numerals

[0055] 20 Battery cell 26 Electrode lead 22 Laminate film 40 Electrode body 50 Electrode sheet 52 Positive electrode sheet 54 Negative electrode sheet 52A, 54A Coated portions 52B, 54B Non-coated portions W Width direction L Length of the end portion of the separator (L1 to L6)

Claims

1. A battery cell in which an electrode body formed by laminating a plurality of positive electrode sheets and a plurality of negative electrode sheets as a plurality of electrode sheets via a plurality of separators is sealed with a laminate film, 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, and the uncoated portion is provided on one or the other side in the width direction of the electrode body and is connected to one end of an electrode lead drawn out from a sealing end portion of the laminate film, in the plurality of separators, the length of an end portion covering the uncoated portion of the electrode sheet is gradually changed in the stacking direction on one or the other side in the width direction of the electrode body, a battery cell.

2. The length of the end portion is gradually changed so as to become longer toward the outer layer side with respect to the position of the sealing end portion of the laminate film, The battery cell according to Claim 1.

3. The end portion has a tapered shape that tapers toward a connection portion between the plurality of electrode sheets and the electrode lead when viewed from the stacking direction, The battery cell according to Claim 1 or Claim 2.

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