Battery cell

Abstract

Provided is a battery cell capable of promoting gas discharge during charging and discharging in a state in which an electrode body is constrained. A battery cell comprises: an elongated electrode body in which a positive electrode, a negative electrode, and a separator are laminated; a band-shaped tape that extends in the short-side direction of the electrode body and is wound around the outer periphery of the electrode body; and a laminated film that seals in a state where the electrode body on which the tape is wound is housed, in which a portion of a bonding surface of the tape that is bonded to the electrode body is provided with a recess that is depressed than other portions.

Description

Technical Field

[0001] The present disclosure relates to a battery cell. Background Art

[0002] U.S. Patent Application Publication No. 2018 / 287184 discloses a battery module in which an electrode assembly is housed in a case. Further, by surrounding the outside of the electrode assembly (electrode body) with a heat-shrinkable protective layer, a structure for suppressing thermal expansion of the electrode assembly is formed.

[0003] As in the structure disclosed in U.S. Patent Application Publication No. 2018 / 287184, by winding a belt or the like around the outer periphery of the electrode body, the electrode body can be constrained. On the other hand, since a heat-shrinkable protective layer or the like is wound around the outer peripheral side of the battery cell, there is a possibility that gas generated during charge and discharge is difficult to discharge. Summary of the Invention

[0004] The present disclosure provides a battery cell that can promote gas discharge during charge and discharge while constraining the electrode body.

[0005] The battery cell according to the first aspect has: a long electrode body formed by laminating a positive electrode, a negative electrode, and a separator; a belt-shaped band extending in the short-side direction of the electrode body and wound around the outer periphery of the electrode body; and a laminated film that is sealed in a state of housing the electrode body around which the band is wound. A concave portion that is recessed more than other portions is provided in a part of the bonding surface of the band that is bonded to the electrode body.

[0006] In the battery cell according to the first aspect, the electrode body is formed by laminating a positive electrode, a negative electrode, and a separator into a long shape. Further, the band is formed in a belt shape, extends in the short-side direction of the electrode body, and is wound around the outer periphery of the electrode body. Moreover, the electrode body around which the band is wound is sealed in a state of being housed in the laminated film. In this way, by winding the band around the outer periphery of the electrode body, the electrode body can be constrained, and displacement of the laminated electrodes can be suppressed.

[0007] Further, a concave portion that is recessed more than other portions is provided in a part of the bonding surface of the band that is bonded to the electrode body. As a result, in the concave portion, the binding force of the electrode body becomes weaker than other portions, so that gas generated in the electrode body can be discharged without remaining inside.

[0008] In the battery cell according to the second aspect, in the first aspect, the concave portion is separated from the surface of the electrode body in a no-load state.

[0009] In the battery cell of the second embodiment, the concave portion of the belt is separated from the surface of the electrode body in the unloaded state, so that the gas inside the electrode body in this part can move freely. Furthermore, the "unloaded state" mentioned here is a concept that broadly includes states other than the state in which the electrode body expands due to the gas generated inside the electrode body, and does not only refer to the state in which no external force is applied to the electrode body and the belt at all.

[0010] In the battery cell of the third embodiment, in the second embodiment, a plurality of the belts are provided at intervals in the longitudinal direction of the electrode body.

[0011] In the battery cell of the third embodiment, a plurality of belts are provided at intervals in the longitudinal direction of the electrode body. Therefore, even for a long electrode body, the misalignment of the stacked electrodes can be efficiently suppressed.

[0012] In the battery cell of the fourth embodiment, in the third embodiment, at least one of the plurality of belts is provided at the central portion in the longitudinal direction of the electrode body.

[0013] In the battery cell of the fourth embodiment, by providing a belt at the central portion in the longitudinal direction of the electrode body where the degree of thermal expansion is the largest, the thermal expansion of the battery cell can be suppressed.

[0014] In the battery cell of the fifth embodiment, in the fourth embodiment, a plurality of the concave portions are provided, and at least a part of the concave portions in the adjacent belts overlap when viewed from the longitudinal direction of the electrode body.

[0015] In the battery cell of the fifth embodiment, when viewed from the longitudinal direction of the electrode body, at least a part of the concave portions in the adjacent belts overlap. Thus, the gas generated in the central portion of the electrode body is easily discharged along the longitudinal direction.

[0016] As described above, according to the battery cell of the present disclosure, the gas discharge during charge and discharge can be promoted while constraining the electrode body. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0018] Figure 1 It is a schematic top view of a main part of a vehicle equipped with a battery pack using the battery cell of the embodiment.

[0019] Figure 2 It is a schematic perspective view of a battery module housing the battery cell of the embodiment.

[0020] Figure 3 It is a top view of the state after removing the upper cover of the battery module.

[0021] Figure 4It is a schematic view of the battery cell of the embodiment observed from the thickness direction.

[0022] Figure 5 It is a schematic view of the electrode body of the embodiment observed from the thickness direction.

[0023] Figure 6 It is a sectional view after cutting along the 6-6 line in Figure 5

[0024] Figure 7 It is a schematic view of the electrode body of the modified example observed from the thickness direction. Detailed Embodiment

[0025] The battery module 11 of the battery cell 20 having the embodiment will be described with reference to the accompanying drawings.

[0026] (Overall Configuration of Vehicle 100)

[0027] Figure 1 It is a schematic top view of the main part of the vehicle 100 equipped with the battery pack 10 having the battery module 11 of the present embodiment. As Figure 1 shown, the vehicle 100 is an electric vehicle (BEV, battery electric vehicle) with the battery pack 10 mounted under the cab. Furthermore, the arrows UP, FR, and LH in each figure respectively 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. When the directions of front, rear, left, right, up, and down are used for description, unless otherwise specified, they represent 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.

[0028] 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. In addition, a motor 108, a gearbox 110, an inverter 112, and a charger 114 are arranged on the vehicle rear side of the battery pack 10.

[0029] The direct current output from the battery pack 10 is adjusted in voltage by the DC / DC converter 102 and then supplied to the electric compressor 104, the PTC heater 106, the inverter 112, etc. In addition, by supplying power to the motor 108 via the inverter 112, the rear wheels rotate to make the vehicle 100 travel.

[0030] A charging port 116 is provided on the right side of the rear part of the vehicle 100. By connecting a charging plug of an external charging device (not shown) to the charging port 116, power can be stored in the battery pack 10 via the in-vehicle charger 114.

[0031] Furthermore, the configuration, structure, etc. of each component constituting the vehicle 100 are not limited to the above configuration. For example, it can also be applied to a hybrid electric vehicle (HV) equipped with an engine or a plug-in hybrid electric vehicle (PHEV). In addition, in the present embodiment, a rear-wheel drive vehicle with the motor 108 mounted on the rear of the vehicle is formed, but it is not limited thereto. A front-wheel drive vehicle with the motor 108 mounted on the front of the vehicle can be formed, or a pair of motors 108 can be mounted on the front and rear of the vehicle. Moreover, it can also be a vehicle equipped with in-wheel motors on each wheel.

[0032] Here, the battery pack 10 is composed of a plurality of battery modules 11. In the present embodiment, as an example, 10 battery modules 11 are provided. Specifically, 5 battery modules 11 are arranged in the vehicle front-rear direction on the right side of the vehicle 100, and 5 battery modules 11 are arranged in the vehicle front-rear direction on the left side of the vehicle 100. In addition, each battery module 11 is electrically connected.

[0033] Figure 2 It is a schematic perspective view of the battery module 11. As Figure 2 shown, the battery module 11 is formed in a substantially rectangular parallelepiped shape with the vehicle width direction as the long side direction. In addition, the housing 13 of the battery module 11 is formed of aluminum alloy. For example, aluminum die-castings are joined to both end portions of an aluminum alloy extrusion by laser welding or the like to form the housing 13 of the battery module 11.

[0034] A pair of voltage terminals 12 and connectors 14 are respectively provided at both ends of the battery module 11 in the vehicle width direction. A flexible printed circuit board 21 described later is connected to the connector 14. In addition, bus bars (not shown) are welded to both ends of the battery module 11 in the vehicle width direction.

[0035] 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 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.

[0036] Figure 3 It is a top view of the state where the upper cover of the battery module 11 is removed. As Figure 3 shown, a battery cell group formed by arranging a plurality of battery cells 20 is housed inside the battery module 11. In the present embodiment, as an example, 24 battery cells 20 are arranged in the vehicle front-rear direction and joined to each other.

[0037] 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 long side direction, and thermistors 23 are respectively provided at both end portions of the flexible printed circuit 21. The thermistors 23 are not joined to the battery cell 20 and are structured to be pressed toward the battery cell 20 side by the upper cover of the battery module 11.

[0038] In addition, one or more buffer plates (not shown) are housed inside the battery module 11. For example, the buffer plate is a thin plate-like member capable of elastic deformation and is disposed between adjacent battery cells 20 with the arrangement direction of the battery cells 20 as the thickness direction. In the present embodiment, as an example, buffer plates are respectively disposed at both end portions in the long side direction and the central portion in the long side direction of the battery module 11.

[0039] Figure 4 It is a schematic view of the battery cell 20 housed in the battery module 11 as viewed from the thickness direction. As Figure 4 shown, the battery cell 20 is formed in a substantially rectangular plate shape, and a long electrode body 19 is housed inside. The electrode body 19 is formed by laminating a positive electrode, a negative electrode, and a separator and is sealed with a laminated film 22.

[0040] In the present embodiment, as an example, a housing portion for the electrode body 19 is formed by folding and bonding a sheet-like laminated film 22 that has been subjected to embossing. Furthermore, two structures, a single cup embossing structure with one embossing process and a double cup embossing structure with two embossing processes, can be adopted, but in the present embodiment, it is a single cup embossing structure with a drawing depth of about 8 mm to 10 mm.

[0041] The upper ends of both end portions in the long side direction of the battery cell 20 are bent. In addition, the upper end portion of the battery cell 20 is bent, and a fixing band 24 is wound along the long side direction at the upper end portion of the battery cell 20.

[0042] Here, terminals (connectors) 26 are respectively provided at both end portions in the long side direction of the battery cell 20. In the present embodiment, as an example, the terminals 26 are provided at positions offset downward from the center in the vertical direction of the battery cell 20. The terminals 26 are joined to a bus bar (not shown) by laser welding or the like.

[0043] The length CW1 of the battery cell 20 in the vehicle width direction is, for example, 530 mm to 600 mm, the length CW2 of the region housing the electrode body 19 is, for example, 500 mm to 520 mm, and the height CH of the battery cell 20 is, for example, 80 mm to 110 mm. Therefore, the battery cell 20 is formed in a long shape, and the directions of the lengths CW1 and CW2 are the long side directions.

[0044] In addition, the thickness of the battery cell 20 is 7.0 mm to 9.0 mm, and the height TH of the terminal 26 is 40 mm to 50 mm.

[0045] Figure 5 It is a schematic view of the electrode body 19 of the embodiment as viewed from the thickness direction. As Figure 5 shown, the electrode body 19 of the present embodiment is formed by laminating a positive electrode, a negative electrode, and a separator into a long shape.

[0046] Although not shown, the positive electrode, the negative electrode, and the separator are structures used in a general secondary battery. For example, the negative electrode includes a current collector made of a metal foil such as a copper foil and a negative electrode active material held on the current collector. The negative electrode active material occludes lithium ions as charge carriers from the non-aqueous electrolyte during charging and discharges them into the non-aqueous electrolyte. The negative electrode active material of the present embodiment uses a silicon-containing material such as a silicon-based carbon composite material, but is not limited thereto. For example, as the negative electrode active material, known negative electrode active materials such as artificial graphite and lithium alloy (LiXM) can also be used. Furthermore, M in LiXM is C, Si, Sn, Sb, Al, Mg, Ti, Bi, Ge, Pb, or P, etc., and X is a natural number. In addition, the negative electrode active material layer formed of the negative electrode active material may also contain a known binder such as styrene-butadiene copolymer.

[0047] In addition, for example, the positive electrode includes a current collector formed of an aluminum foil or the like and a positive electrode active material. The positive electrode active material discharges lithium ions into the non-aqueous electrolyte or occludes lithium ions from the non-aqueous electrolyte. The positive electrode active material uses known positive electrode active materials such as LiNiO2, LiNi 1 / 3Co 1 / 3 Mn 1 / 3 O2. In addition, it may further contain carbon black, lithium phosphate, and a known binder.

[0048] The separator is a sheet-like member that electrically insulates the positive electrode and the negative electrode and provides a movement path for lithium ions between the positive electrode active material and the negative electrode active material. As the separator, a porous film formed of polyethylene, polypropylene, or the like can be cited. Furthermore, the separator may be a single-layer structure or a multi-layer structure.

[0049] Here, in the present embodiment, belt-like bands 30, 32, 34, 36, and 38 are wound around the outer periphery of the electrode body 19. The bands 30, 32, 34, 36, and 38 are provided at intervals in the long side direction of the electrode body 19. In the present embodiment, as an example, five bands are provided at equal intervals on the outer periphery of the electrode body 19.

[0050] The belt 34 is provided at the central portion in the long side direction of the electrode body 19 and extends in the short side direction of the electrode body 19. In addition, a plurality of recesses 34A are provided on the belt 34. In the present embodiment, as an example, two recesses 34A are provided on the belt facing one surface of the electrode body 19, and two recesses 34A are similarly provided on the belt facing the other surface.

[0051] The belts 32 and 36 are provided at intervals on both sides of the belt 34. For example, the distance between the belt 34 and the belt 32 is equal to the distance between the belt 34 and the belt 36. In addition, a plurality of recesses 32A are provided on the belt 32, and a plurality of recesses 36A are provided on the belt 36. Specifically, two recesses 32A are provided on the belt facing one surface of the electrode body 19, and two recesses 32A and 36A are similarly provided on the belt facing the other surface.

[0052] The belt 30 is provided on the opposite side of the belt 34 with respect to the belt 32. In addition, the belt 38 is provided on the opposite side of the belt 34 with respect to the belt 36. A plurality of recesses 30A are provided on the belt 30, and a plurality of recesses 38A are provided on the belt 38. Specifically, two recesses 30A are provided on the belts 30 and 38 facing one surface of the electrode body 19, and two recesses 30A and 38A are similarly provided on the belts 30 and 38 facing the other surface.

[0053] Here, when viewed from the long side direction of the electrode body 19, at least a part of the recesses in the adjacent belts overlap. In the present embodiment, as an example, the recesses 30A, 32A, 34A, 36A, and 38A overlap when viewed from the long side direction of the electrode body 19. Although not shown, the recesses formed on the belts facing the other surface (back surface) of the electrode body 19 also overlap when viewed from the long side direction of the electrode body 19.

[0054] Figure 6 It is a sectional view cut along the 6-6 line of Figure 5 . As shown in this Figure 6 , recesses 30A and a joint portion 30B are formed on the joint surface of the belt 30 facing the electrode body 19. The joint portion 30B is joined to the surface of the electrode body 19. In addition, the recess 30A is recessed more than the other part (joint portion 30B) and is separated from the surface of the electrode body 19 in the unloaded state. That is, the recess 30A becomes a non-joint portion that does not engage with the surface of the electrode body 19.

[0055] In this way, the recesses 30A and the joint portions 30B are alternately provided in the extending direction of the belt 30. In addition, for Figure 5Similarly, in the other belts 32, 34, 36, and 38 shown, recesses and engaging portions are alternately provided in the extending direction of the belts, and the recesses serve as non-engaging portions.

[0056] (Function)

[0057] Next, the function of the battery cell 20 of the present embodiment will be described.

[0058] In the battery cell 20 of the present embodiment, the electrode body 19 is formed in a long shape by laminating a positive electrode, a negative electrode, and a separator. In addition, the belts 30, 32, 34, 36, and 38 are formed in a belt shape, extend in the short side direction of the electrode body 19, and are wound around the outer periphery of the electrode body 19. Further, the electrode body 19 around which the belts 30, 32, 34, 36, and 38 are wound is sealed in a state of being accommodated in the laminate film 22. Thus, by winding the belts 30, 32, 34, 36, and 38 around the outer periphery of the electrode body 19, the electrode body 19 can be constrained, and the misalignment of the laminated electrodes can be suppressed.

[0059] In addition, in each of the belts 30, 32, 34, 36, and 38, recesses 30A, 32A, 34A, 36A, and 38A that are recessed more than other portions are provided in a part of the joint surface that is joined to the electrode body 19. Thereby, in the recesses 30A, 32A, 34A, 36A, and 38A, the binding force of the electrode body 19 becomes weaker than other portions, so that the gas generated in the electrode body 19 can be discharged without staying inside.

[0060] Moreover, in the present embodiment, since the recesses 30A, 32A, 34A, 36A, and 38A formed in the belts 30, 32, 34, 36, and 38 in the unloaded state are separated from the surface of the electrode body 19, the gas inside the electrode body 19 can move freely in this part.

[0061] In addition, in the present embodiment, since a plurality of belts are provided at intervals in the long side direction of the electrode body 19, even the long-shaped electrode body 19 can efficiently suppress the misalignment of the laminated electrodes.

[0062] In addition, in the present embodiment, by providing the belt 34 at the central portion in the long side direction of the electrode body 19 where the thermal expansion is the largest, the thermal expansion of the battery cell 20 can be suppressed.

[0063] Moreover, in the present embodiment, when viewed from the long side direction of the electrode body 19, at least a part of the recesses in the adjacent belts overlap. Thereby, the gas generated in the central portion of the electrode body 19 is easily discharged along the long side direction.

[0064] Particularly in the present embodiment, when viewed from the long side direction of the electrode body 19, the recesses 30A, 32A, 34A, 36A, and 38A coincide. Thus, the gas generated in the central portion of the electrode body 19 easily passes through the inside of the portion where the recesses are formed and is discharged along the long side direction. In this way, the battery cell 20 of the present embodiment can promote the discharge of gas during charge and discharge while constraining the electrode body 19.

[0065] Furthermore, in the above-described embodiment, as Figure 5 shown, the recesses 30A, 32A, 34A, 36A, and 38A are provided at the same position in the long side direction of the electrode body 19, but it is not limited thereto. For example, the structure of the modified example shown in Figure 7 may also be adopted.

[0066] (Modified Example)

[0067] Figure 7 is a schematic view of the modified example of the electrode body 19 viewed from the thickness direction. As shown in this Figure 7 figure, in this modified example, the strip 42 is provided between the strip 30 and the strip 34 instead of the strip 32. In addition, the strip 44 is provided between the strip 34 and the strip 38 instead of the strip 36.

[0068] A recess 42A is provided on the strip 42. The recess 42A is formed wider than the recess 30A of the strip 30 and is provided at a position that does not overlap with the recess 30A when viewed from the long side direction of the electrode body 19. Furthermore, one recess 42A is provided on the strip opposite to one surface of the electrode body 19, and one recess 42A is also provided on the strip opposite to the other surface of the electrode body 19.

[0069] A recess 44A is provided on the strip 44. The recess 44A is formed wider than the recess 30A of the strip 30 and is provided at a position that does not overlap with the recess 30A when viewed from the long side direction of the electrode body 19. Furthermore, one recess 44A is provided on the strip opposite to one surface of the electrode body 19, and one recess 44A is also provided on the strip opposite to the other surface of the electrode body 19.

[0070] As in this modified example, by providing the recesses at different positions in the long side direction of the electrode body 19, the path of the gas generated in the electrode body 19 can be changed. In addition, since the joint portions and non-joint portions where the strip is joined to the electrode body are alternately arranged in the long side direction of the electrode body 19, it is possible to suppress a local decrease in the binding force of the electrode body 19.

[0071] As described above, the battery cell 20 of the embodiment and the modification example have been described, but it is not limited thereto. Without departing from the gist of the present disclosure, it can of course be implemented in various ways. For example, the width of the tape wound around the electrode body 19 can be changed, or the width of the tape can be changed at the central portion and the end portion in the longitudinal direction of the electrode body 19.

[0072] In addition, one tape having a large width may be wound around the electrode body 19. In this case, by providing the concave portion in such a manner that gas can be easily discharged to the joint surface of the tape, even a tape having a large width can promote gas discharge during charge and discharge while restraining the electrode body.

[0073] Moreover, in the above-described embodiment, the concave portion is a structure that is separated from the surface of the electrode body 19 in a no-load state, but it is not limited thereto. For example, the concave portion provided in the tape may be a structure that contacts the surface of the electrode body 19 in a no-load state. Even in this case, the binding force of the electrode body 19 is weaker in the concave portion than in other portions, so that a gas discharge path can be set inside this portion.

[0074] Regarding the above-described embodiment, the following remarks are disclosed.

[0075] (Remark 1)

[0076] A battery cell having:

[0077] A long electrode body formed by laminating a positive electrode, a negative electrode, and a separator;

[0078] A belt-shaped tape that extends in the short side direction of the electrode body and is wound around the outer periphery of the electrode body; and

[0079] A laminated film that seals the electrode body wound with the tape in a housed state,

[0080] A concave portion that is recessed more than other portions is provided in a part of the joint surface of the tape that is joined to the electrode body.

[0081] (Remark 2)

[0082] The battery cell according to Remark 1, wherein the concave portion is separated from the surface of the electrode body in a no-load state.

[0083] (Remark 3)

[0084] The battery cell according to Remark 1 or Remark 2, wherein a plurality of the tapes are provided at intervals in the longitudinal direction of the electrode body.

[0085] (Remark 4)

[0086] The battery cell according to Note 3, wherein at least one of the belts is disposed at a central portion in the longitudinal direction of the electrode body.

[0087] (Note 5)

[0088] The battery cell according to Note 3 or Note 4, wherein a plurality of the recesses are provided.

[0089] When viewed from the longitudinal direction of the electrode body, at least a part of the recesses in the adjacent belts overlap.

[0090] (Note 6)

[0091] The battery cell according to Note 3, wherein in the adjacent belts, the recess of one belt and the recess of the other belt are disposed at different positions when viewed from the longitudinal direction of the electrode body.

Claims

1. A battery cell comprising: A long electrode body formed by stacking the positive electrode, the negative electrode and the separator; a belt-shaped tape extending in the short-side direction of the electrode body and wound around the outer circumference of the electrode body; and A laminate film for sealing the electrode body wound with the tape stored therein, A portion of the surface of the tape that is joined to the electrode body is provided with a recessed portion that is recessed compared to other portions. 2 . The battery cell according to claim 1 , wherein the recess is spaced apart from the surface of the electrode body in a no-load state. 3 . The battery cell according to claim 1 , wherein a plurality of the belts are provided at intervals in the longitudinal direction of the electrode body. 4 . The battery cell according to claim 3 , wherein at least one of the plurality of strips is provided at a central portion in a longitudinal direction of the electrode body.

5. The battery cell according to claim 4, A plurality of the recesses are provided, When viewed in the longitudinal direction of the electrode body, at least a portion of the recessed portions in the adjacent strips overlap. 6 . The battery cell according to claim 3 , wherein, in the adjacent strips, the recessed portion of one strip and the recessed portion of the other strip are provided at different positions when viewed in the longitudinal direction of the electrode body.

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