Stacked battery

Abstract

The present invention relates to a laminated battery having a battery element and a laminated film covering and sealing the battery element, the laminated film having a welded portion in which end portions are overlapped with each other and inner surfaces are welded, the laminated film having a welded portion side surface in which the welded portion is formed, an opposite side surface opposite the welded portion side surface, and a pair of main surfaces, the laminated film has a pair of main surfaces that are orthogonal to the welded part side surface and the opposite side surface, the surface area of the pair of main surfaces is larger than the surface area of the welded part side surface and the opposite side surface, and the laminated film has an uneven shape on at least one of the welded part side surface and the opposite side surface.

Description

Technical Field

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

[0002] In the past, stacked batteries have been studied in which battery elements such as an electrode body are covered and sealed with a stacked film and which have a welded portion formed by overlapping the ends of the stacked film and welding the inner surfaces.

[0003] For example, Japanese Patent Publication No. 2006-49054 discloses a sheet-type battery, in which two electrodes of a battery power generation element are led out to the outside, the battery power generation element is clamped from the top and bottom by a concave-convex plate material as an internal component, the entirety of the battery power generation element is wrapped with a sheet, and the sheet is airtightly joined and sealed by heat welding or the like at the end portions, etc. The concave-convex plate material is a single-sided concave-convex plate, and has a concave-convex portion on the surface opposite to the surface clamping the battery power generation element. In addition, the sheet also has concave-convex portions corresponding to the concave-convex portions of the concave-convex plate material, and the concave-convex portions are combined with each other to form convex portions and concave portions on the upper and lower sides of the sheet-type battery. Summary of the invention

[0004] However, when forming a welded portion where the ends of the laminated film overlap each other and the inner surfaces are welded, in order to improve the airtightness, a method is adopted in which the battery element in a state covered by the laminated film is placed in a decompression space, and the portions where the ends of the laminated film overlap each other are thermally welded under a decompression state to form the welded portion. However, when the laminated battery after the welded portion is formed is taken out of the decompression space and released from the decompression state, sometimes the welded portion side of the laminated film and the opposite side thereof are bent, and the structural efficiency of the battery is reduced.

[0005] The present disclosure has been made in view of the above-mentioned actual situation, and an object thereof is to provide a stacked battery capable of improving the structural efficiency of the battery.

[0006] Means for solving the above-mentioned problems include the following aspects.

[0007] <1>

[0008] A laminated battery having:

[0009] Battery components; and

[0010] a laminated film covering and encapsulating the battery element,

[0011] The laminate film has a welded portion formed by overlapping the end portions and welding the inner surfaces thereof,

[0012] The laminate film has a welding portion side surface on which the welding portion is formed, an opposite side surface opposite to the welding portion side surface, and a pair of main surfaces, the pair of main surfaces are orthogonal to the welding portion side surface and the opposite side surface, and the area of ​​the pair of main surfaces is larger than the area of ​​the welding portion side surface and the opposite side surface,

[0013] The laminate film has a concavo-convex shape on at least one of the side surface of the weld portion and the opposite side surface.

[0014] <2>

[0015] As above <1> In the laminated battery described above, the laminated film has the concavo-convex shape on the opposite side surface.

[0016] <3>

[0017] As above <1> or <2> In the laminated battery, the laminated film has the concavo-convex shape in which concave portions and convex portions are repeated from one main surface side to the other main surface side on at least one of the welded portion side and the opposite side.

[0018] <4>

[0019] As above <1> to <3> In the laminated battery described in any one of the above, the laminated film has the uneven shape over the entire surface of at least one of the side surface of the weld portion and the opposite side surface.

[0020] According to the present disclosure, a stacked battery capable of improving the structural efficiency of the battery can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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 components, and in which:

[0022] Figure 1 is a schematic cross-sectional view exemplarily showing a stacked battery according to an embodiment of the present disclosure;

[0023] Figure 2 is a schematic cross-sectional view exemplarily showing a conventional laminated battery;

[0024] Figure 3 It is a schematic plan view showing the main parts of the vehicle;

[0025] Figure 4 It is a schematic three-dimensional diagram of a battery module;

[0026] Figure 5 It is a plan view of a state where the upper cover of the battery module is removed;

[0027] Figure 6A schematic diagram showing a battery cell housed in a battery module as viewed from the thickness direction. DETAILED DESCRIPTION

[0028] Laminated battery

[0029] The laminated battery according to the embodiment of the present disclosure has a battery element and a laminated film covering and enclosing the battery element. The laminated film has a welded portion formed by overlapping the ends and welding the inner surfaces. In addition, the laminated film has a welded portion side surface formed with the welded portion, an opposite side surface opposite to the welded portion side surface, and a pair of main surfaces, the pair of main surfaces are orthogonal to the welded portion side surface and the opposite side surface, and the area of ​​the pair of main surfaces is larger than the area of ​​the welded portion side surface and the opposite side surface. In addition, the laminated film has a concave-convex shape on at least one of the welded portion side surface and the opposite side surface.

[0030] Hereinafter, one embodiment of a stacked battery according to an embodiment of the present disclosure will be described with reference to the drawings.

[0031] Each of the drawings shown below is a schematic diagram, and the size and shape of each part are appropriately exaggerated for easy understanding.

[0032] Figure 1 : is a schematic cross-sectional view exemplarily showing a stacked battery according to an embodiment of the present disclosure. Figure 1 The upper part of shows the laminated battery before being released from the decompressed state when the welded portion is formed in the laminated film. Figure 1 The lower part of shows the laminated battery after being released from the decompressed state when the welded portion is formed in the laminated film.

[0033] Figure 1 The stacked battery 20 shown has an electrode body 5 as an example of a battery element formed into a roughly rectangular plate shape, and a stacked film 28 covering and sealing the electrode body 5. The stacked film 28 has a welded portion 28A formed by overlapping the ends and welding the inner surfaces. The inner side of the stacked film 28 is closed by the welded portion 28A. The stacked film 28 has four faces: a welded portion side face 20A, an opposite side face 20B, and a pair of main faces 20C and 20D. The welded portion side face 20A is arranged on the side where the welded portion 28A is formed. The opposite side face 20B is opposite to the welded portion side face 20A. The pair of main faces 20C and 20D are orthogonal to the welded portion side face 20A and the opposite side face 20B, and the area of ​​the pair of main faces 20C and 20D is larger than the area of ​​the welded portion side face 20A and the opposite side face 20B. Furthermore, the main surfaces 20C and 20D are surfaces that are oriented in the stacking direction when a plurality of stacked type batteries 20 are further stacked to form a battery stack.

[0034] Furthermore, the laminated film 28 has a concavo-convex shape 20X on the opposite side surface 20B.

[0035] According to the laminated battery of the embodiment of the present disclosure, the structural efficiency of the battery can be improved by the laminated film having the concavo-convex shapes on the opposite side surfaces.

[0036] Here, using Figure 2 A method for forming a welded portion in a laminate film in a conventional laminate type battery will be described. Figure 2 is a schematic cross-sectional view exemplarily showing a conventional laminated battery. Figure 2 The upper part of shows the laminated battery before being released from the reduced pressure state when the welded portion is formed in the laminated film. Figure 2 The lower part of shows the laminated battery after being released from the decompressed state when the welded portion is formed in the laminated film.

[0037] Figure 2 The stacked battery 200 shown in the upper part of has an electrode body 5 formed in a roughly rectangular plate shape, and a stacked film 228 covering and sealing the electrode body 5. The stacked film 228 has a welded portion 228A formed by overlapping the ends and welding the inner surfaces. The stacked film 228 has four surfaces: a welded portion side surface 200A, an opposite side surface 200B, and a pair of main surfaces 200C and 200D. The welded portion side surface 200A is arranged on the side where the welded portion 228A is formed. The opposite side surface 200B is opposite to the welded portion side surface 200A. The pair of main surfaces 200C and 200D are orthogonal to the welded portion side surface 200A and the opposite side surface 200B, and the area of ​​the pair of main surfaces 200C and 200D is larger than the area of ​​the welded portion side surface 200A and the opposite side surface 200B. In addition, the laminated film 228 has no irregularities on either the weld portion side surface 200A or the opposite side surface 200B.

[0038] In the stacked battery 200, when forming the welded portion 228A on the stacked film 228, first, the electrode body 5 is covered with the stacked film 228 so that the ends of the stacked film 228 overlap each other. Next, the electrode body 5 and the stacked film 228 are placed in a reduced pressure space, and the portions where the ends of the stacked film 228 overlap each other are heat-welded in a reduced pressure state to form the welded portion 228A. Since the electrode bodies 5 generally have size differences between the individual ones, the stacked film 228 is usually formed to have a size that has a margin for the size of the electrode body 5. Therefore, by heat-welding the stacked film 228 in a state arranged in the reduced pressure space as described above, the sealing property between the stacked film 228 and the electrode body 5 can be improved.

[0039] However, when the laminated battery 200 after the welded portion 228A is formed is taken out of the decompression space and released from the decompression state, a pressure difference is generated inside and outside the laminated film 228, and sometimes the laminated film 228 is bent 200X on the opposite side 200B. When the bending 200X is generated, the opposite side 200B of the laminated film 228 is as shown in FIG. Figure 2As shown, the opposite side 200B may be curved, and as a result, the position of the end of the opposite side 200B may be extended from position a to position b. In addition, when using the conventional laminated battery 200, it is assumed that the opposite side 200B of the laminated film 228 is curved 200X and the position of the wall 210 of the battery case that accommodates the laminated battery 200 is designed to be closer than Figure 2 That is, since the opposite side 200B of the laminated film 228 is curved by the deflection 200X, the structural efficiency may be reduced. In addition, the deflection in the laminated film 228 may occur not only on the opposite side 200B but also on the side 200A of the welded portion.

[0040] In contrast, according to the laminated battery of the embodiment of the present disclosure, the laminated film has a concavo-convex shape on at least one of the side surface of the weld and the opposite side surface. Therefore, even if the laminated battery after the weld is formed is taken out of the decompression space and released from the decompression state, and a pressure difference is generated inside and outside the laminated film, the deflection in the laminated film on the opposite side surface and the side surface of the weld can be suppressed. That is, the deflection that is about to occur is absorbed by the concavo-convex shape, and it is not easy to form deflection.

[0041] So, for example, Figure 1 As shown, the position of the end of the opposite side 20B after release from the decompression state is Figure 2 Compared with the conventional stacked battery shown in FIG. 1 , the extent of expansion from position c to position d can be suppressed. Figure 2 Compared with the case of the conventional laminated battery shown in FIG. 1 , the position of the wall 210 of the battery case accommodating the laminated battery 20 can be shifted in the direction of the arrow S. The structural efficiency of the battery can be improved.

[0042] In this way, with the stacked battery according to the embodiment of the present disclosure, the structural efficiency of the battery can be improved.

[0043] exist Figure 1 , the laminated film 28 is shown to have a concavo-convex shape 20X on the opposite side 20B (the side opposite to the weld side 20A), but the laminated battery according to the embodiment of the present disclosure is not limited to this. Figure 1 The weld side 20A may have a concavo-convex shape, and both the weld side 20A and the opposite side 20B may have a concavo-convex shape. The generation of deflection in the laminated film may sometimes also occur on the weld side, but the generation of deflection on the weld side 20A can be suppressed by having a concavo-convex shape.

[0044] However, in the laminated battery according to the embodiment of the present disclosure, it is preferred that at least the opposite side surfaces of the laminated film have a concavo-convex shape from the viewpoint of making it easier to improve the structural efficiency of the battery.

[0045] exist Figure 1 In FIG. 1 , it is shown that the concave and convex portions extend from the main surface 20C side of one side to the main surface 20D side of the other side (that is, from Figure 1 The laminated film 28 may have a concave-convex shape that is repeated from the top to the bottom in the main surface 20C, but the laminated battery according to the embodiment of the present disclosure is not limited to this. That is, the concave and convex portions may be arranged in a direction orthogonal to the direction from the main surface 20C side of one side toward the main surface 20D side of the other side (that is, Figure 1 The concave and convex shapes are repeated in the depth direction.

[0046] However, according to the stacked battery of the embodiment of the present disclosure, from the viewpoint of making it easier to improve the structural efficiency of the battery, it is preferred that the concave portion and the convex portion extend from the main surface 20C side on one side to the main surface 20D side on the other side (i.e., from Figure 1 The concave and convex shapes are repeated (from top to bottom).

[0047] exist Figure 1 In the figure, a method is shown in which the entire surface of the opposite side 20B has a concavo-convex shape 20X, but the stacked battery according to the embodiment of the present disclosure is not limited to this. That is, the opposite side 20B of the stacked film 28 may have a concavo-convex shape only in a portion. For example, the stacked film 28 may have a concavo-convex shape only in the area on the main surface 20C side of the opposite side 20B, and may have a concavo-convex shape only in the area on the main surface 20D side of the other side of the opposite side 20B. In addition, the concavo-convex shape may be formed only in the area at the center (that is, the concavo-convex shape is not formed in the area on the main surface 20C side and the area on the main surface 20D side). Furthermore, in a direction orthogonal to the direction from the main surface 20C side of one side toward the main surface 20D side of the other side (that is, Figure 1 In the depth direction of the structure, a concave-convex shape may be formed only in a portion.

[0048] In addition, when the laminate film has a concavo-convex shape on the side of the weld portion, the side of the weld portion of the laminate film has a concavo-convex shape in the direction from the main surface 20C side of one side toward the main surface 20D side of the other side (that is, Figure 1 In addition, on the side of the welded portion of the laminated film, in a direction orthogonal to the direction from the main surface 20C side of one side toward the main surface 20D side of the other side (i.e., Figure 1 In the depth direction of the structure, a concave-convex shape may be formed only in a portion.

[0049] However, in the laminated battery according to the embodiment of the present disclosure, from the viewpoint of further improving the structural efficiency of the battery, the laminated film preferably has an uneven shape over the entire surface of at least one of the side surface of the weld portion and the opposite side surface.

[0050] exist Figure 1 In the figure, a method of forming a concave-convex shape having three protrusions and three concave parts on the opposite side 20B is shown, but the stacked battery according to the embodiment of the present disclosure is not limited to this. The concave-convex shape of the stacked film in at least one of the side of the welding portion and the opposite side can be a shape having at least one protrusion and one concave part. In addition, from the viewpoint of being easier to improve the structural efficiency of the battery, preferably, the concave-convex shape formed on at least one of the side of the welding portion and the opposite side of the stacked film is a concave-convex shape having more than three protrusions and concave parts respectively. More preferably, it is a concave-convex shape having more than five protrusions and concave parts respectively. Further preferably, it is a concave-convex shape having more than ten protrusions and concave parts respectively. In addition, there is no particular restriction on the upper limit of the number of protrusions and concave parts, for example, it can also be a concave-convex shape having less than 30 protrusions and concave parts respectively.

[0051] Next, a battery module, a battery assembly, and a vehicle having a laminated battery according to an embodiment of the present disclosure will be described using the accompanying drawings. Figure 5 and Figure 6 The battery cell described in employs a stacked-type battery according to an embodiment of the present disclosure.

[0052] Overall structure of vehicle 100

[0053] Figure 3 1 is a schematic plan view showing the main parts of a vehicle 100 to which the battery assembly 10 according to the embodiment is applied. Figure 3 As shown, the vehicle 100 is an electric vehicle (BEV) equipped with a battery assembly 10 under the floor. In addition, the arrows UP, FR, and LH in the respective drawings respectively indicate the upper side in the vehicle vertical direction, the front side in the vehicle front-rear direction, and the left side in the vehicle width direction. When the front-rear, left-right, up-down and left-right directions are used for explanation, unless otherwise specified, the front-rear direction in the vehicle front-rear direction, the left-right direction in the vehicle width direction, and the up-down direction in the vehicle vertical direction are indicated.

[0054] The vehicle 100 of the present embodiment, as an example, is provided with a DC / DC converter 102, an electric compressor 104, and a positive temperature coefficient (PTC) heater 106 on the vehicle front side relative to the battery assembly 10. In addition, a motor 108, a gear box 110, an inverter 112, and a charger 114 are provided on the vehicle rear side relative to the battery assembly 10.

[0055] The DC current output from the battery pack 10 is regulated in voltage by the DC / DC converter 102 and then supplied to the electric compressor 104, the PTC heater 106, the inverter 112, etc. Furthermore, the electric power is supplied to the motor 108 via the inverter 112, so that the rear wheels rotate and the vehicle 100 travels.

[0056] A charging port 116 is provided at 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 assembly 10 via the on-vehicle charger 114.

[0057] In addition, the configuration and structure of the various components constituting the vehicle 100 are not limited to the above-mentioned structure. For example, it can also be applied to a hybrid vehicle (HV) or a plug-in hybrid electric vehicle (PHEV) equipped with an engine. In addition, in the present 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, and the vehicle can also be a front-wheel drive vehicle with the motor 108 mounted at the front of the vehicle. A pair of motors 108 can also be mounted at the front and rear of the vehicle. Furthermore, it can also be a vehicle equipped with hub motors on each wheel.

[0058] Here, the battery assembly 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, the battery modules 11 are electrically connected to each other.

[0059] Figure 4 1 is a schematic three-dimensional diagram of the battery module 11. Figure 4 As shown, the battery module 11 is formed into a substantially rectangular parallelepiped shape with the vehicle width direction as the length 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 aluminum alloy extrusion by laser welding or the like, thereby forming the outer shell of the battery module 11.

[0060] 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 22 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.

[0061] 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 top-bottom direction of, for example, 80 mm to 110 mm.

[0062] Figure 5 1 is a plan view of the battery module 11 with the upper cover removed. Figure 5 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 are connected to each other.

[0063] A flexible printed circuit board (FPC) 22 is disposed on the battery cell 20. The flexible printed circuit board 22 is formed in a strip shape with the vehicle width direction as the longitudinal direction. Thermistors 24 are provided at both ends of the flexible printed circuit board 22. The thermistor 24 is a structure in which it is not joined to the battery cell 20 but is pressed toward the battery cell 20 side by the upper cover of the battery module 11.

[0064] In addition, one or more buffers (not shown) are accommodated inside the battery module 11. For example, the buffer is a thin plate-shaped member that can be elastically deformed and is arranged between adjacent battery cells 20 with the arrangement direction of the battery cells 20 as the thickness direction. In this embodiment, as an example, buffers are arranged at both ends and the center of the battery module 11 in the longitudinal direction.

[0065] Figure 6 2 is a schematic diagram of a battery cell 20 housed in a battery module 11 as viewed from the thickness direction. Figure 6 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 28.

[0066] In this embodiment, as an example, the electrode body receiving portion is formed by folding and laminating the embossed sheet-shaped laminated film 28. In addition, although two structures, a single cup embossing structure in which embossing is performed at one location and a double cup embossing structure in which embossing is performed at two locations, can be adopted, in this embodiment, a single cup embossing structure with a drawing depth of about 8 mm to 10 mm is used.

[0067] The upper ends of both ends of the battery cell 20 in the longitudinal direction are bent, and the corners form an outer contour. In addition, the upper end of the battery cell 20 is bent, and a fixing band 30 is wound around the upper end of the battery cell 20 along the longitudinal direction.

[0068] Here, terminals (electrode pieces) 26 are provided at both ends in the longitudinal direction of the battery cell 20. In the present embodiment, as an example, the terminal 26 is provided at a position offset downward from the center in the vertical direction of the battery cell 20. The terminal 26 is joined to a bus bar (not shown) by laser welding or the like.

[0069] 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 accommodating 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, and the height TH of the terminal 26 is 40 mm to 50 mm.

Claims

1. A stacked battery, wherein: have: Battery components; as well as a laminated film covering and encapsulating the battery element, The laminate film has a welded portion formed by overlapping the end portions and welding the inner surfaces thereof, The laminate film has a welding portion side surface on which the welding portion is formed, an opposite side surface opposite to the welding portion side surface, and a pair of main surfaces, the pair of main surfaces are orthogonal to the welding portion side surface and the opposite side surface, and the area of ​​the pair of main surfaces is larger than the area of ​​the welding portion side surface and the opposite side surface, The laminate film has a concavo-convex shape on at least one of the side surface of the weld portion and the opposite side surface.

2. The stacked battery according to claim 1, wherein: The laminated film has the concavo-convex shape on the opposite side surface.

3. The stacked battery according to claim 1, wherein: The laminate film has the concavo-convex shape in which concave portions and convex portions are repeated from the one main surface side to the other main surface side on at least one of the weld portion side and the opposite side.

4. The stacked battery according to claim 1, wherein: The laminate film has the uneven shape over the entire surface of at least one of the side surface of the weld portion and the opposite side surface.

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