Laminated film, battery cell, and battery module

Abstract

The invention relates to a laminated film, a battery cell, and a battery module. The laminated film is provided with a housing part for housing the electrode body, and is sealed in a state in which the electrode body is housed. The housing section has a side wall section facing the peripheral end surface of the electrode body, and at least a portion of the side wall section is provided with a concavo-convex portion.

Description

Technical Field

[0001] The present invention relates to a laminated film, a battery cell and a battery module. Background Art

[0002] Japanese Patent Application Laid-Open No. 2006-49054 discloses a sheet-type battery (battery cell) formed by wrapping an electrode body with a sheet (laminated film). In the sheet-type battery described in Japanese Patent Application Laid-Open No. 2006-49054, the electrode body is sandwiched by a concave-convex plate material, and the concave-convex plate material is covered by the sheet. As a result, the surface of the sheet-type battery becomes concave-convex to ensure heat dissipation characteristics. Summary of the invention

[0003] However, in the sheet-type battery described in Japanese Patent Application Laid-Open No. 2006-49054, both surfaces are formed in a concavo-convex shape, so there is room for improvement in terms of improving the loading performance when a plurality of batteries are accommodated in a case and modularized.

[0004] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laminate film, a battery cell, and a battery module in which thermal expansion is suppressed and loading properties are ensured in a laminate film for housing an electrode body.

[0005] The laminate film of the first embodiment includes a housing portion for housing the electrode assembly, and is sealed in a state where the electrode assembly is housed.

[0006] The housing portion includes a side wall portion facing the peripheral end surface of the electrode body, and a concavo-convex portion is provided on at least a portion of the side wall portion.

[0007] In the first embodiment of the laminate film, there is a storage portion for storing the electrode body, and the storage portion is configured to include a side wall portion opposite to the peripheral end surface of the electrode body. Here, since the concavo-convex portion is formed on at least a portion of the side wall portion, even when gas is generated by repeated charge and discharge, the concavo-convex portion can expand and contract to suppress thermal expansion.

[0008] In addition, by making the portions of the housing portion facing the main surface of the electrode body into a shape that does not interfere with each other, the adjacent laminated films are in contact with each other when modularized, and thus the loading performance can be ensured.

[0009] A laminate film according to a second aspect is the laminate film according to the first aspect, wherein the housing portion has a bottom wall portion facing the main surface of the electrode body, and the bottom wall portion is a flat surface without projections and recesses.

[0010] In the laminate film of the second embodiment, the bottom wall portion facing the main surface of the electrode body is formed in a flat shape. Therefore, if the battery cells are arranged so that the main surfaces overlap each other, the loading performance can be improved.

[0011] A battery cell according to a third aspect includes:

[0012] An electrode body, which is formed by stacking a positive electrode, a negative electrode and a separator; and

[0013] The laminate film according to the second aspect houses the electrode body.

[0014] The battery cell of the third aspect has the same effects as those of the second aspect.

[0015] A battery module according to a fourth aspect includes a housing for housing the battery cell according to the third aspect in a state where a plurality of the battery cells according to the third aspect are arranged.

[0016] The plurality of battery cells are arranged such that the adjacent battery cells have the bottom walls facing each other.

[0017] In the battery module of the fourth aspect, the plurality of battery cells housed in the case are arranged so that the bottom walls face each other, and therefore the concave and convex portions do not need to interfere with each other.

[0018] As described above, according to the laminate film, the battery cell, and the battery module of the present invention, in the laminate film for housing the electrode body, the loading property is ensured while suppressing the thermal expansion. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0020] Figure 1 is a schematic plan view showing a main part of a vehicle to which the battery pack according to the embodiment is applied;

[0021] Figure 2 is a schematic three-dimensional diagram of a battery module;

[0022] Figure 3 is a top view of a state where an upper cover of a battery module is removed;

[0023] Figure 4 This is a schematic diagram of a battery cell housed in a battery module as viewed from the thickness direction;

[0024] Figure 5 is a schematic cross-sectional view of a battery cell in an embodiment;

[0025] Figure 6 is a schematic cross-sectional view of a laminated film before sealing in an embodiment;

[0026] Figure 7 is a schematic cross-sectional view of a battery cell in a modified example; and

[0027] Figure 8 It is a schematic cross-sectional view of a laminate film before sealing in a modified example. DETAILED DESCRIPTION

[0028] A battery module 11 to which the laminate film 22 according to the embodiment is applied will be described with reference to the drawings.

[0029] Overall structure of vehicle 100

[0030] Figure 1 1 is a schematic top view showing the main parts of a vehicle 100 to which the battery pack 10 according to the embodiment is applied. Figure 1 As shown, the vehicle 100 is a battery electric vehicle (BEV) equipped with a battery pack 10 under the floor. It should be noted that the arrows UP, FR, and LH in each figure respectively indicate the upper side of the vehicle in the up-down direction, the front side of the vehicle in the front-back direction, and the left side in the vehicle width direction. When the directions of front, back, left, right, up, and down are used for explanation, unless otherwise specified, they indicate the front and back of the vehicle in the front-back direction, the left and right of the vehicle in the width direction, and the up and down of the vehicle in the up-down direction.

[0031] As an example, the vehicle 100 of the present embodiment has a DC / DC converter 102, an electric compressor 104, and a positive temperature coefficient (PTC) heater 106 disposed on the vehicle front side relative to the battery pack 10. In addition, a motor 108, a gear box 110, an inverter 112, and a charger 114 are disposed on the vehicle rear side relative to the battery pack 10.

[0032] The DC current output from battery pack 10 is regulated in voltage by DC / DC converter 102 and then supplied to electric compressor 104, PTC heater 106, inverter 112, etc. In addition, by supplying power to motor 108 via inverter 112, the rear wheels rotate and vehicle 100 travels.

[0033] A charging port 116 is provided on the right side of the rear portion of the vehicle 100 . By connecting a charging plug of an external charging device (not shown) to the charging port 116 , electric power can be stored in the battery pack 10 via the on-vehicle charger 114 .

[0034] It should be noted that the configuration and structure of the various components constituting the vehicle 100 are not limited to the above-mentioned structure. For example, the present embodiment can also be applied to a hybrid electric vehicle (HV) or a plug-in hybrid electric vehicle (PHEV) equipped with an engine. In addition, the present embodiment is set as a rear-wheel drive vehicle with the motor 108 mounted at the rear of the vehicle, but is not limited to this. The present embodiment can be a front-wheel drive vehicle with the motor 108 mounted at the front of the vehicle, or a pair of motors 108 can be mounted at the front and rear of the vehicle. Furthermore, the present embodiment can also be a vehicle with a hub motor on each wheel.

[0035] Here, the battery pack 10 is configured to include a plurality of battery modules 11. In the present embodiment, as an example, 10 battery modules 11 are provided. Specifically, five battery modules 11 are arranged along the vehicle front-rear direction on the right side of the vehicle 100, and five battery modules 11 are arranged along the vehicle front-rear direction on the left side of the vehicle 100. In addition, each battery module 11 is electrically connected.

[0036] Figure 2 1 is a schematic three-dimensional diagram of the battery module 11. Figure 2 As shown, the battery module 11 is formed into a substantially rectangular parallelepiped shape with the vehicle width direction as the long side direction. In addition, the outer shell of the battery module 11 is formed of an aluminum alloy. For example, an aluminum die casting is joined to both ends of an extruded material of an aluminum alloy by laser welding or the like, thereby forming the outer shell of the battery module 11.

[0037] A pair of voltage terminals 12 and a connector 14 are provided at both ends of the battery module 11 in the vehicle width direction. A flexible printed circuit board 21 described later is connected to the connector 14. Bus bars (not shown) are welded to both ends of the battery module 11 in the vehicle width direction.

[0038] The battery module 11 has a length MW in the vehicle width direction of, for example, 350 mm to 600 mm, a length ML in the vehicle front-rear direction of, for example, 150 mm to 250 mm, and a height MH in the vehicle vertical direction of, for example, 80 mm to 110 mm.

[0039] Figure 3 FIG. 1 is a top view of the battery module 11 with the upper cover removed. Figure 3 As shown, a plurality of battery cells 20 are housed in an aligned state inside the battery module 11. In the present embodiment, as an example, 24 battery cells 20 are aligned in the vehicle front-rear direction and bonded to each other.

[0040] 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. Thermistors 23 are provided at both ends of the flexible printed circuit 21. The thermistor 23 is a structure that is not bonded to the battery cell 20 and is pressed toward the battery cell 20 by the upper cover of the battery module 11.

[0041] In addition, one or more buffers (not shown) are stored inside the battery module 11. For example, the buffer is a thin plate-shaped member that can be elastically deformed and is arranged between the battery cells 20 adjacent to each other in the thickness direction of the arrangement direction of the battery cells 20. In this embodiment, as an example, buffers are arranged at both ends and the center of the battery module 11 in the long side direction.

[0042] Figure 4 2 is a schematic diagram of a battery cell 20 housed in a battery module 11 as viewed from the thickness direction. Figure 4 As shown, the battery cell 20 is formed in a substantially rectangular plate shape, and an electrode body (not shown) is accommodated inside. The electrode body is formed by laminating a positive electrode, a negative electrode, and a separator, and is sealed by a laminate film 22 .

[0043] In this embodiment, as an example, the storage part of the electrode body is formed by folding and laminating the embossed sheet-shaped laminate film 22. It should be noted that both single cup embossing structure with embossing at one location and double cup embossing structure with embossing at two locations can be adopted, but in this embodiment, a single cup embossing structure with a drawing depth of about 8 mm to 10 mm is used.

[0044] The upper ends of both ends of the battery cell 20 in the longitudinal direction are bent, and the corners become the outer shape. In addition, the upper end of the battery cell 20 is bent, and the fixing band 24 is wound around the upper end of the battery cell 20 along the longitudinal direction.

[0045] Here, terminals (tabs) 26 are provided at both ends of the battery cell 20 in the longitudinal direction. In the present embodiment, as an example, the terminals 26 are provided at positions offset downward from the vertical center of the battery cell 20. The terminals 26 are joined to bus bars (not shown) by laser welding or the like.

[0046] 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 of the battery cell 20 that houses the electrode body is, for example, 500 mm to 520 mm. The height CH of the battery cell 20 is, for example, 80 mm to 110 mm. In addition, the thickness of the battery cell 20 is 7.0 mm to 9.0 mm. The height TH of the terminal 26 is 40 mm to 50 mm.

[0047] Figure 5 2 is a schematic cross-sectional view of a battery cell 20 in the embodiment. Figure 5 As shown, the battery cell 20 of this embodiment is composed of an electrode body 30 formed by stacking a positive electrode, a negative electrode and a separator, and a laminate film 22 that accommodates the electrode body 30. The electrode body 30 constitutes a lithium-ion battery, for example, and lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, etc. are used as the active material of the positive electrode. In addition, graphite and lithium titanate are used as the active material of the negative electrode. In addition, the interior of the battery cell 20 is filled with an electrolyte.

[0048] The laminate film 22 includes a housing portion 32 for housing the electrode assembly 30 , and is sealed in a state where the electrode assembly 30 is housed in the housing portion 32 .

[0049] Figure 6 2 is a schematic cross-sectional view of the laminate film 22 before sealing in the embodiment. Figure 6 As shown, the laminate film 22 before sealing has a recessed portion formed by embossing or the like, and the recessed portion constitutes the storage portion 32. In addition, the periphery of the recessed portion (storage portion 32) becomes a sealing portion 22A formed in a sheet shape, and in the sealing portion 22A, the laminate films 22 overlapped are welded to each other.

[0050] Here, the storage portion 32 includes a bottom wall portion 32A and a side wall portion 32B. The bottom wall portion 32A is a portion facing the main surface of the electrode body 30, and when the battery module 11 is constructed, adjacent battery cells are arranged so that the bottom walls 32A face each other.

[0051] The side wall portion 32B is a portion of the housing portion 32 that faces the peripheral end surface of the electrode body 30 and is formed in a concavoconvex shape. For example, after the housing portion 32 is formed by embossing, only the side wall portion 32B is formed in a concavoconvex shape by press working. Therefore, the bottom wall portion 32A is formed in a flat surface without concavoconvex shapes.

[0052] effect

[0053] Next, the function of the laminate film 22 of the present embodiment will be described.

[0054] The laminate film 22 of the present embodiment includes a housing portion 32 for housing the electrode body 30, and the housing portion 32 is configured to include a side wall portion 32B that faces the peripheral end surface of the electrode body 30. Here, since the concavo-convex portion is formed on at least a portion of the side wall portion 32B, even when gas is generated by repeated charge and discharge, the concavo-convex portion expands and contracts, thereby suppressing thermal expansion of the battery cell 20.

[0055] Furthermore, since the bottom wall portion 32A facing the main surface of the electrode body 30 in the housing portion 32 is formed flat, the flat surfaces of adjacent laminate films 22 contact each other when modularized, and the concavo-convex portions do not interfere with each other, thereby ensuring loading performance.

[0056] In particular, the battery cells 20 of the present embodiment are arranged so that the bottom wall portions 32A face each other in the state of the battery module 11 , and therefore the concavo-convex portions do not need to interfere with each other.

[0057] It should be noted that in the above embodiment, a single cup embossing structure in which one concave portion is embossed on the laminate film 22 is used, but the present invention is not limited thereto. Figure 7 and Figure 8 The structure of the double cup type embossing is shown.

[0058] Modifications

[0059] Figure 7 is a schematic cross-sectional view of a battery cell 50 in a modified example. Figure 8 2 is a schematic cross-sectional view of a laminate film 52 before sealing in a modified example. Figure 7 As shown, a battery cell 50 according to the present modification example is configured to include an electrode body 30 and a laminate film 52 that houses the electrode body 30 .

[0060] The laminate film 52 includes a housing portion 54 for housing the electrode assembly 30 , and is sealed in a state where the electrode assembly 30 is housed in the housing portion 54 .

[0061] like Figure 8 As shown, the laminate film 52 before sealing has two recesses formed by embossing or the like, and these recesses overlap to form a storage portion 54. In addition, the periphery of each recess (storage portion 54) becomes a sealing portion 52A formed in a sheet shape, and in this sealing portion 52A, the overlapping laminate films 52 are welded to each other.

[0062] Here, the recessed portion constituting the storage portion 54 includes a bottom wall portion 54A and a side wall portion 54B. The bottom wall portion 54A is a portion facing the main surface of the electrode body 30, and when constituting the battery module, adjacent battery cells are arranged so that the bottom walls 54A face each other.

[0063] The side wall portion 54B is formed in a concavoconvex shape at a portion of the housing portion 54 that faces the peripheral end surface of the electrode body 30. For example, after the housing portion 54 is formed by embossing, only the side wall portion 54B is formed in a concavoconvex shape by press working. Therefore, the bottom wall portion 54A is formed in a flat surface without concavoconvex shapes.

[0064] According to this modification, by adopting the double cup embossing structure, even when the electrode body 30 is thick, it can be accommodated.

[0065] The laminate film 22, the battery cell 20, and the battery module 11 of the present embodiment are described above, but are not limited thereto and can be implemented in various ways without departing from the gist of the present invention. For example, in the above embodiment, the four side wall portions 32B constituting the storage portion 32 are formed in a concave-convex shape as a whole, but the present invention is not limited thereto, and only a part of the side wall portion 32B may be formed in a concave-convex shape.

[0066] In addition, in the above embodiment, the bottom wall portion 32A is formed in a planar shape, but the present invention is not limited thereto. For example, a plurality of recesses may be formed in the bottom wall portion 32A. In this case, interference between adjacent battery cells does not occur, and thermal expansion can be suppressed.

[0067] Furthermore, in the above-mentioned embodiment, the side wall portion 32B is formed with a substantially corrugated concave-convex portion when viewed from the side, but the present invention is not limited thereto. For example, a substantially corrugated concave-convex portion may be formed when viewed from the bottom wall portion 32A. That is, the shape of the concave-convex shape is not limited.

[0068] The following supplementary notes are disclosed with respect to the above-mentioned embodiment.

[0069] Note 1

[0070] A laminated film, wherein

[0071] The electrode assembly is sealed with a storage portion for storing the electrode assembly.

[0072] A concavo-convex portion is formed on at least a portion of a side wall portion of the housing portion that faces a peripheral end surface of the electrode body.

[0073] Note 2

[0074] The laminate film according to Supplementary Note 1, wherein in the housing portion, a bottom wall portion facing a main surface of the electrode body is formed in a flat surface shape without irregularities.

[0075] Note 3

[0076] A battery cell, wherein the battery cell has:

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

[0078] The laminate film according to Supplementary Note 1 or Supplementary Note 2 houses the electrode body.

[0079] Note 4

[0080] A battery module, wherein:

[0081] A housing is provided for accommodating the battery cell according to Supplementary Note 3 in a state where a plurality of the battery cells according to Supplementary Note 3 are arranged.

[0082] The plurality of battery cells are arranged such that the adjacent battery cells have the bottom walls facing each other.

Claims

1. A laminated film, wherein The laminated film comprises: a storage portion for storing the electrode body, The laminate film is sealed in a state where the electrode body is housed. The housing portion includes a side wall portion facing the peripheral end surface of the electrode body, and a concavo-convex portion is provided in at least a portion of the side wall portion.

2. The laminated film according to claim 1, wherein The housing portion has a bottom wall portion facing the main surface of the electrode body, and the bottom wall portion is a flat surface without projections and depressions.

3. A battery cell, wherein: The battery cell has: An electrode body having a positive electrode, a negative electrode and a separator stacked thereon; and The laminate film according to claim 2 houses the electrode body.

4. A battery module, wherein: The battery module comprises: a housing for housing the battery cell according to claim 3 in a state where a plurality of the battery cells according to claim 3 are arranged; The plurality of battery cells are arranged such that the adjacent battery cells have the bottom walls facing each other.

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