Battery cell and manufacturing method thereof

Abstract

To provide a battery cell and a manufacturing method thereof that can suppress the occurrence of a short circuit near an electrode lead while suppressing an increase in cost due to an increase in the number of parts.SOLUTION: A battery cell 20 includes an electrode body 40 in which a positive electrode sheet 52 and a negative electrode sheet 54 as an electrode sheet 50 are laminated with a separator 60 between them, a laminate film 22 that seals the electrode body 40, and an electrode lead 26 that is connected to uncoated portions 52B, 54B, in which an electrode active material is not coated on a sheet-like current collector, at at least one end in the width direction W of the electrode sheet 50, and is drawn out from a sealed end 30 of the laminate film 22, and the uncoated portions 52B, 54B are formed at the end in the width direction W of the electrode sheet 50 so as to include a base end position 40R1 of an R region 40R that is curved in an R shape toward the sealed end 30.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a battery cell and a method for manufacturing the battery cell.

Background Art

[0002] Patent Document 1 below describes a laminated film battery cell including a power storage element in which a positive electrode and a negative electrode are laminated via a separator, a laminated film for sealing the power storage element, a current collector tab connected to the battery element and drawn out from a sealed end portion of the laminated film.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an electrode body in which a positive electrode sheet and a negative electrode sheet as electrode sheets are laminated via a separator, like the power storage element of Patent Document 1 above, a coated portion where an electrode active material is coated on a current collector of the electrode sheet and an uncoated portion where the electrode active material is not coated are formed. The coated portion of the electrode sheet is disposed to face the coated portion of another electrode sheet via the separator. Thereby, an electrolyte (ion) enters and exits (intercalates) between the coated portions and contributes to the battery reaction. Further, the uncoated portion is provided at a position drawn out from the separator at one end in the width direction of the electrode sheet and is connected to the electrode lead.

[0005] By the way, in a battery cell in which the electrode body is sealed with a laminated film, the ends of the electrode sheet and the separator are curved in an R shape toward the sealed end of the laminated film. For this reason, a displacement occurs in the position of the end of the separator that ensures insulation between the electrode sheets, and there is a risk of short circuit due to direct contact between the coated portions of the electrode sheets curved in an R shape and the coated portions of other electrode sheets.

[0006] At the end where the electrode body and the electrode lead are connected, in order to prevent such a short circuit, a protective film for insulation 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 the increase in the number of components.

[0007] In view of the above facts, an object of the present invention is to obtain a battery cell and a method for manufacturing a battery cell that can suppress the occurrence of a short circuit in the vicinity of the electrode lead while suppressing the cost increase due to the increase in the number of components.

Means for Solving the Problems

[0008] The battery cell according to the first aspect includes an electrode body in which a positive electrode sheet and a negative electrode sheet as electrode sheets are laminated via a separator, a laminate film that seals the electrode body, and at least one end in the first width direction of the electrode sheet, which is connected to an uncoated portion where no electrode active material is applied to the sheet-shaped current collector, and an electrode lead drawn out from the sealed end of the laminate film. The uncoated portion is formed to include the base end position of the R region that is curved in an R shape toward the sealed end at the end of the electrode sheet in the first width direction.

[0009] The battery cell according to the first aspect includes an electrode body in which a positive electrode sheet and a negative electrode sheet as electrode sheets are laminated via a separator. The electrode body is connected to an electrode lead at at least one end in the first width direction of the electrode sheet. The electrode lead is connected to an uncoated portion where no electrode active material is applied to the sheet-shaped current collector in the electrode sheet and is drawn out from the sealed end of the laminate film to the outside of the battery cell.

[0010] 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, displacement of the position of the end of the separator that ensures insulation between the electrode sheets occurs, and there is a risk of a short circuit occurring when the coated portions of the electrode sheets curved in an R shape come into direct contact with the coated portions of the other electrode sheets.

[0011] Here, according to the first aspect, the uncoated portion of the electrode sheet is formed so as to include the base end position of the R region curved in an R shape toward the sealed end at the end in the first width direction. For this reason, the coated portion of the electrode sheet is not formed within the R region. Thereby, it is possible to suppress direct contact between the coated portions of the electrode sheets due to displacement of the position of the end of the separator, and it is possible to ensure insulation between the electrode sheets without using a protective sheet for insulation. As a result, it is possible to suppress a cost increase due to an increase in the number of components and suppress the occurrence of a short circuit in the vicinity of the electrode lead.

[0012] In the battery cell according to the second aspect, in the first aspect, the length of the uncoated portion in the second width direction orthogonal to the first width direction is set to be shorter than the length of the coated portion in the second width direction of the electrode sheet on which the electrode active material is coated on the current collector.

[0013] In a battery cell in which the electrode body is sealed with a laminate film, when the uncoated portion of the electrode sheet is set to be smaller than the width of the coated portion, connection to the electrode lead becomes easier. On the other hand, in the R region of the electrode body, displacement of the positions of the ends of the electrode sheet and the separator is likely to occur.

[0014] According to the second aspect, in the electrode sheet, the length of the uncoated portion in the second width direction orthogonal to the first width direction is set to be shorter than the length of the coated portion in the second width direction, and it is formed so as to include the base end position of the R region. For this reason, while facilitating connection to the electrode lead, it is possible to effectively suppress the occurrence of a short circuit at a location where a short circuit is likely to occur due to the bending of the coated portion of the electrode sheet.

[0015] In the battery cell according to the third aspect, in the first aspect or the second aspect, the electrode body is configured such that the length of the uncoated portion in the first width direction becomes longer as the electrode sheet is disposed on the outer layer side with respect to the sealed end portion.

[0016] In a battery cell in which the electrode body is sealed with a laminate film, the greater the curvature of the R region becomes as the electrode sheet is disposed on the outer layer side with respect to the sealed end portion of the laminate film, the more likely it is that displacement of the ends of the electrode sheet and the separator will occur.

[0017] In the battery cell according to the third aspect, the electrode body is configured such that the length of the uncoated portion in the first width direction becomes longer as the electrode sheet is disposed on the outer layer side with respect to the sealed end portion. For this reason, the length of the uncoated portion in the first width direction is set longer in a portion where a short circuit is likely to occur due to the curvature of the coated portion of the electrode sheet, and it is possible to effectively suppress the occurrence of a short circuit.

[0018] The method for manufacturing a battery cell according to the fourth aspect is the method for manufacturing a battery cell according to the first aspect, including a step of applying an electrode active material to the current collector, and a step of removing the electrode active material applied to a region including the base end position of the R region at an end of the current collector in the first width direction.

[0019] In the method for manufacturing a battery cell according to the fourth aspect, after applying an electrode active material to the current collector, the battery cell is manufactured by removing the applied electrode active material from a region including the base end position of the R region at an end of the current collector in the first width direction. As a result, it is possible to obtain a battery cell that can suppress the occurrence of a short circuit in the vicinity of the electrode lead while suppressing an increase in cost due to members. Further, in the fourth aspect, since the electrode active material at the end of the current collector in the first width direction is removed after the application of the electrode active material, it is possible to suppress the occurrence of "standing up" in which the thickness of the electrode active material layer becomes thick at the boundary between the coated portion and the uncoated portion.

Advantages of the Invention

[0020] As described above, in the battery cell and the method for manufacturing the battery cell according to the present invention, 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.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0022] Hereinafter, with reference to FIGS. 1 to 6(B), an embodiment of the present invention will be described.

[0023] (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 an 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. Note that the arrows UP and FR in each figure Arrow LH indicates the upper side in the vehicle up-and-down direction, the front side in the vehicle front-and-rear direction, and the left side in the vehicle width direction, respectively. When using the directions of front, rear, left, right, up, and down to describe, unless otherwise specified, it shall indicate the front and rear in the vehicle front-and-rear direction, the left and right in the vehicle width direction, and the up and down in the vehicle up-and-down direction.

[0024] As an example, in the vehicle 100 of this embodiment, a DC / DC converter 102, an electric compressor 104, and a PTC (Positive Temperature Coefficient) heater 106 are arranged on the front side of the vehicle with respect to the battery pack 10. Also, on the rear side of the vehicle with respect to the battery pack 10, a motor 108, a gearbox 110, an inverter 112, and a charger 114 are arranged.

[0025] 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 run.

[0026] 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) from the charging port 116, power can be stored in the battery pack 10 via the in-vehicle charger 114.

[0027] 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. It 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, it may be a vehicle equipped with in-wheel motors on each wheel.

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

[0029] FIG. 2 is a schematic perspective view of the battery module 11. As shown in FIG. 2, the battery module 11 includes a module case 16 forming an outer shell. The module case 16 is formed in a substantially rectangular parallelepiped shape with the vehicle width direction as the longitudinal direction. Also, the module case 16 is formed of an aluminum alloy. For example, the module case 16 is formed by joining aluminum die-casts to both ends of an extruded material of an aluminum alloy by laser welding or the like.

[0030] 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. Also, bus bars (not shown) are welded to both ends of the battery module 11 in the vehicle width direction.

[0031] 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.

[0032] FIG. 3 is a plan view of the battery module 11 with the upper lid removed. As shown in FIG. 3, a plurality of battery cells 20 stacked on each other are accommodated inside the module case 16. Each battery cell 20 is accommodated in a posture with the stacking direction as the thickness direction. In this embodiment, 24 battery cells 20 are arranged (stacked) in the vehicle longitudinal direction and adhered to each other to form a stacked body.

[0033] For easier understanding of the description, in each of FIGS. 3 to 6(B), the direction indicated by arrow W is defined as the width direction of the battery cell 20, the direction indicated by arrow H is defined as the height direction (vertical direction) of the battery cell 20, and the direction indicated by 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 later 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.

[0034] A flexible printed circuit (FPC) 21 is disposed on the battery cell 20. The flexible printed circuit 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 21, respectively. The thermistors 23 are not adhered to the battery cell 20 and are configured to be pressed toward the battery cell 20 side by the upper lid of the battery module 11.

[0035] 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 disposed 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 disposed at both longitudinal ends and the central portion in the longitudinal direction of the module case 16, respectively.

[0036] 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.

[0037] 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 have 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 in which the electrode body 40 is accommodated is formed on the side surface.

[0038] FIG. 5 is a schematic view seen from the height direction H in a state where the battery cell 20 is disassembled. 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.

[0039] In the present embodiment, embossing is performed on one side of the second laminate film 22B to form the accommodating portion 221. The laminate film 22 can adopt both a single cup embossing structure with one embossing and a double cup embossing structure with two embossings. 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.

[0040] On one side in 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 in 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.

[0041] On one side and the other side in 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).

[0042] 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.

[0043] (Electrode body) The electrode body 40 is configured by alternately laminating a plurality of electrode sheets 50 and separators 60. The plurality of electrode sheets 50 include 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 laminated via the separators 60.

[0044] (Positive electrode sheet) The positive electrode sheet 52 is configured by coating a positive electrode active material (electrode active material) 522 on the surface of a sheet-shaped positive electrode current collector (positive electrode current collector) 521 (see FIG. 6(B)). Further, the positive electrode sheet 52 has a coated portion 52A in which the positive electrode active material 522 is coated on the surface of the positive electrode current collector 521 and an uncoated portion 52B in which the positive electrode active material 522 is not coated on the surface of the positive electrode current collector 521.

[0045] The positive electrode current collector 521 is made of a metal foil such as aluminum foil, for example. 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 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.), and a lithium manganese-based oxide (e.g., LiMn2O4).

[0046] The uncoated portion 52B is provided at one end in the width direction W of the positive electrode sheet 52. The tip of the uncoated portion 52B protrudes from one end in the width direction W of the separator and is integrated with the uncoated portions 52B of other positive electrode sheets 52 at a predetermined position in the stacking direction (the thickness direction D in FIG. 5) of the electrode body 40 to form a current collecting portion 56 on the positive electrode side (see FIG. 6(B)). 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, and the first electrode lead 26A is disposed between the current collecting portion 56 on the positive electrode side and the first laminate film 22A. Thereby, the first electrode lead 26A is connected to the current collecting portion 56 on the positive electrode side. One end of the first electrode lead 26A is drawn out from the sealed end portion 30 of the first laminate film 22A and the second laminate film 22B to the outside of the battery cell 20 in the vicinity of the current collecting portion 56 on the positive electrode side.

[0047] On the other hand, the other end in the width direction W of the positive electrode sheet 52 is a non-projecting end portion disposed in the facing region with the separator 60. This non-projecting end portion is composed of a coated portion 52A coated with the positive electrode active material 522, does not protrude from the other end in the width direction W of the separator 60, and is disposed so as to face the negative electrode sheet 54 via the separator 60.

[0048] (Negative electrode sheet) The negative electrode sheet 54 is formed by coating a negative electrode active material (electrode active material) 542 on the surface of a sheet-shaped negative electrode current collector (electrode current collector) 541 (see FIG. 6(B)). Further, the negative electrode sheet 54 has 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.

[0049] The negative electrode current collector 541 is composed of, for example, a metal foil such as a 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 material capable of occluding 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.

[0050] One end of the negative electrode sheet 54 in the width direction W is a non-projecting end portion disposed in the facing region with the separator 60. This non-projecting end portion is composed of the coated portion 54A where the negative electrode active material 542 is coated, does not project from one end of the separator 60 in the width direction W, and is configured to face the second electrode sheet 50 through the separator 60.

[0051] On the other hand, an uncoated portion 54B is provided at the other end of the negative electrode sheet 54 in the width direction W. The tip of the uncoated portion 54B projects from the other end of the separator in the width direction W and is integrated with the uncoated portions 54B of other negative electrode sheets 54 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 56 on the negative electrode side (see FIG. 6(B)). In the present embodiment, the second electrode lead 26B is disposed between the current collecting portion 56 on the negative electrode side and the first laminate film 22A. Thereby, the second electrode lead 26B is connected to the current collecting portion 56 on the negative electrode side. One end of the second electrode lead 26B is drawn out to the outside of the battery cell 20 from the sealing end portion 30 of the first laminate film 22A and the second laminate film 22B near the current collecting portion 56 on the negative electrode side.

[0052] FIG. 6(A) is an enlarged side view showing a partial cutout of one end of the battery cell 20 in the width direction W of the region P in FIG. 5. FIG. 6(B) is an enlarged cross-sectional view of the end of the battery cell 20 cut along the line 6B-6B in FIG. 6(A).

[0053] As shown in FIG. 6(A), the length L2 in the height direction H of the uncoated portion 52B of the positive electrode sheet 52 is set shorter than the length L1 in the height direction H of the coated portion 52A corresponding to the width of the first electrode lead 26A. Although not shown, the length in the height direction H of the uncoated portion 54B of the negative electrode sheet 54 is also set shorter than the length in the height direction of the coated portion 54A.

[0054] On the other hand, as shown in FIG. 6(B), at the end of the battery cell 20 in the width direction W, an R region 40R is formed in which the ends of the electrode sheet 50 (positive electrode sheet 52, negative electrode sheet 54) and the separator 60 are curved in an R shape toward the sealing end 30 of the laminate film. In FIG. 6(B), the base end position 40R1 and the tip position 40R2 of the R region 40R of the positive electrode sheet 52 are shown. As shown in this figure, the uncoated portion 52B of the positive electrode sheet 52 is formed to include the base end position 40R1 of the R region 40R. Therefore, in the R region 40R at one end of the electrode body 40 in the width direction W, the uncoated portion 52B of the positive electrode sheet 52 drawn toward the current collector 56 is arranged.

[0055] Here, the uncoated portion 52B of the positive electrode sheet 52 is set such that the length L3 in the width direction W becomes longer as the positive electrode sheet is arranged on the outer layer side of the electrode body 40. As an example, in the positive electrode sheet 52X arranged on the outermost layer, the position of the boundary between the coated portion 52A and the uncoated portion 52B is the base end position 40R1 of the R region 40R. In the other positive electrode sheets 52 arranged on the inner layer side of the outermost electrode sheet 50X, the position of the boundary between the coated portion 52A and the uncoated portion 52B is offset to the outside (one side in the width direction W) from the base end position 40R1 of the R region 40R as the positive electrode sheet on the inner layer side.

[0056] Although not shown in the drawings, the uncoated area provided on the other side in the width direction W of the negative electrode sheet 54 has the same configuration. That is, the uncoated portion 54B of the negative electrode sheet 54 is formed to include the base end position of the R region 40R. For this reason, the uncoated portion 54B of the negative electrode sheet 54 drawn toward the current collector portion 56 is disposed in the R region 40R at the other end in the width direction W of the electrode body 40. Further, the uncoated portion 54B of the negative electrode sheet 54 is set so that the length in the width direction W becomes longer as the negative electrode sheet 54 disposed on the outer layer side of the electrode body 40 is larger.

[0057] (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. When viewed from the stacking direction of the electrode body 40, the uncoated portion 52B of the positive electrode sheet 52 protrudes from one end in the width direction W of the separator 60. The uncoated portion 54B of the negative electrode sheet 54 protrudes from the other end in the width direction W of the separator 60.

[0058] (Method for manufacturing a battery cell) The battery cell 20 described above is manufactured, as an example, through a source process, a stacking process, a pressing process, a terminal welding process, a cell drying process, a liquid injection / encapsulation process, an activation process, and an evaluation process.

[0059] In the source process, the positive electrode sheet 52, the negative electrode sheet 54, and the separator 60 that constitute the electrode body 40 are formed. In this source process, a coating process is performed in which an electrode active material is coated on the current collectors of the positive electrode sheet 52 and the negative electrode sheet 54 as the electrode sheet 50. Here, the positive electrode sheet 52 will be described as an example. In the coating process, an uncoated portion is formed at one end of the positive current collector 521 in the width direction W. The uncoated portion in this process is set such that the length in the width direction W is smaller than the length in the width direction W of the R region 40R in the state where the electrode body 40 is configured. That is, in this process, a coated portion 52A is formed at the base end position 40R1 of the R region 40R of the positive electrode sheet 52.

[0060] In the source process, after the coating process, a removal process is performed to remove the positive electrode active material from the surface of the positive current collector 521. In the removal process, as an example, the positive electrode active material 522 is removed from a predetermined region including the base end position 40R1 of the R region 40R at one end of the positive current collector 521 in the width direction W by a known doctor blade method or the like. As a result, the uncoated portion 52B of the positive electrode sheet 52 can be formed including the base end position 40R1 of the R region 40R. Further, in this process, a so-called "ear standing" formed by the thickness of the layer of the positive electrode active material 522 being thicker than other parts at the end face of the boundary between the coated portion 52A and the uncoated portion 52B of the positive electrode sheet 52 is removed.

[0061] In the lamination process, the positive electrode sheet 52 and the negative electrode sheet 54 are laminated alternately with the separator 60 interposed therebetween. In the pressing process, the electrode body 40 is formed by pressing the laminate formed by alternately laminating the positive electrode sheet 52 and the negative electrode sheet 54 with the separator 60 interposed therebetween in the lamination direction. In the terminal welding process, the electrode leads 26 are welded to one side and the other side of the electrode body 40 in the width direction W. In the cell drying process, the electrode body 40 is vacuum dried to remove the moisture contained in the electrode body 40. In the liquid injection and sealing process, the electrode body 40 is sealed with a laminate film, and an electrolytic solution is injected therein to form the battery cell 20. In the activation process, the battery cell 20 is initially charged and then subjected to a high-temperature aging treatment. In the evaluation process, inspections such as the cell voltage and the battery resistance are performed to select a battery cell 20 that exhibits predetermined performance. By the above steps, the battery cell 20 according to the above embodiment can be manufactured.

[0062] 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.

[0063] (Function and Effect) As described above, in the battery cell 20 according to the present embodiment, an electrode body 40 in which a positive electrode sheet 52 and a negative electrode sheet 54 as electrode sheets 50 are laminated via a separator 60 is provided. The electrode body 40 is connected to the electrode lead 6 at at least one end in the first width direction W of the electrode sheet 50. The electrode lead 26 is connected to the uncoated portions 52B and 54B on the sheet-like current collectors (positive electrode current collector 521, negative electrode current collector 541) where the electrode active material is not coated on the electrode sheet 50, and is drawn out from the sealed end portion 30 of the laminate film 22 to the outside of the battery cell 20.

[0064] Incidentally, in the battery cell 20 in which the electrode body 40 is sealed with the laminate film 22, an R region 40R is formed in which the ends of the electrode sheet 50 and the separator 60 are curved in an R shape toward the sealing end portion 30 of the laminate film 22 (see FIG. 6(B)). In this R region 40R, since displacement of the end portion of the separator 60 that ensures insulation between the electrode sheets 50 easily occurs, if the coated portions 52A and 54A of the electrode sheet 50 are arranged in the R region 40R, there is a risk of short circuit due to direct contact with the coated portions 52A and 54B of the other electrode sheets 50. In order to prevent such a short circuit, if an insulating protective sheet is arranged at the end of the electrode sheet 50, there arises a problem of cost increase due to an increase in members.

[0065] On the other hand, according to the present embodiment, the uncoated portions 52B and 54B of the electrode sheet 50 are formed so as to include the base end position 40R1 of the R region 40R. For this reason, the coated portions 52A and 54A of the electrode sheet 50 are not formed within the R region. Thereby, direct contact between the coated portions of the electrode sheet 50 caused by displacement of the end portion of the separator 60 can be suppressed, and insulation between the electrode sheets 50 can be ensured without using an insulating protective sheet. As a result, it is possible to suppress the cost increase 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.

[0066] Further, in the present embodiment, since the uncoated portion of the electrode sheet is set to be smaller than the width of the coated portion, connection with the electrode lead 26 is easy. On the other hand, in the R region 40R of the electrode body 40, displacement of the ends of the electrode sheet 50 and the separator 60 easily occurs. However, as described above, the uncoated portions 52B and 54B of the electrode sheet 50 are formed so as to include the base end position 40R1 of the R region 40R. For this reason, while facilitating connection with the electrode lead 26, it is possible to effectively suppress the occurrence of a short circuit at a location where a short circuit easily occurs due to the curvature of the coated portions 52A and 54A of the electrode sheet 50.

[0067] Further, in the present embodiment, since the electrode body 40 is sealed with the laminate film 22, the curvature of the R region 40R becomes larger as the electrode sheet 50 is disposed closer to the outer layer side with respect to the sealing end portion 30 of the laminate film 22. Therefore, displacement of the end portions of the electrode sheet 50 and the separator 60 is more likely to occur on the outer layer side of the electrode body 40.

[0068] Therefore, in the present embodiment, the length in the width direction W of the uncoated portions 52B and 54B is configured to be longer as the electrode sheet 50 is disposed closer to the outer layer side with respect to the sealing end portion of the laminate film 22. For this reason, the length L3 (see FIG. 6(B)) in the width direction W of the uncoated portions 52B and 54B is set longer at locations where a short circuit is likely to occur due to the bending of the coated portions 52A and 54A of the electrode sheet 50, and it is possible to effectively suppress the occurrence of a short circuit.

[0069] In addition, the battery cell 20 described in the above embodiment is manufactured by applying an electrode active material to a current collector (positive current collector 521, negative current collector 541) and then removing the applied electrode active material from a region including the base end position 40R1 of the R region 40R at the end in the width direction W of the current collector. As a result, a battery cell 20 can be obtained that can suppress an increase in cost due to members and suppress the occurrence of a short circuit in the vicinity of the electrode lead 26. Further, in the present embodiment, since the electrode active material at the end in the width direction W of the current collector is removed after the application of the electrode active material, it is possible to suppress the occurrence of "standing up" in which the thickness of the electrode active material layer becomes thick at the boundary between the coated portions 52A and 54A and the uncoated portions 52B and 54B. By suppressing the standing up of the end face of the electrode active material, it is possible to suppress the occurrence of a leakage defect caused by local compression of the separator during the expansion and contraction of the charge and discharge cycle.

[0070] 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 in the width direction W of the uncoated portion becomes longer as the electrode sheet 50 disposed on the outer layer side with respect to the sealing end portion 30 of the laminate film 22, but it is not limited thereto. The length L3 in the width direction W of the uncoated portion may be the same value for each electrode sheet. In this case, the uncoated portion of each electrode sheet 50 may be set in accordance with the base end position 40R1 of the R region 40R of the outermost electrode sheet 50.

Explanation of Signs

[0071] 20 Battery cell 26 Electrode lead 22 Laminate film 40 Electrode body 40R R region 50 Electrode sheet 52 Positive electrode sheet 54 Negative electrode sheet 52A, 54A Coated portion 52B, 54B Uncoated portion W Width direction (first width direction) H Height direction (second width direction)

Claims

1. An electrode body in which a positive electrode sheet and a negative electrode sheet as electrode sheets are laminated via a separator, A laminate film for sealing the electrode body, At least one end portion in the first width direction of the electrode sheet, connected to an uncoated portion where no electrode active material is applied to the sheet-like current collector, and an electrode lead drawn out from the sealed end portion of the laminate film, A battery cell comprising: The uncoated portion is formed so as to include the base end position of the R region curved in an R shape toward the sealed end portion at the end portion of the electrode sheet in the first width direction. Battery cell.

2. The length in the second width direction orthogonal to the first width direction of the uncoated portion is set shorter than the length in the second width direction of the coated portion where the electrode active material is applied to the current collector in the electrode sheet. The battery cell according to claim 1.

3. The electrode body is configured such that the length in the first width direction of the uncoated portion becomes longer as the electrode sheet disposed on the outer layer side with respect to the sealed end portion is larger. The battery cell according to claim 1 or claim 2.

4. A method for manufacturing the battery cell according to claim 1, A step of applying an electrode active material to the current collector, A step of removing the electrode active material applied to a region including the base end position of the R region at an end portion in the first width direction of the current collector, A method for manufacturing a battery cell including:

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