Laminated batteries

Abstract

To provide laminated batteries that can improve the structural efficiency of batteries. [Solution] A laminated battery comprising a battery element and a laminate film that covers and encloses the battery element, wherein the laminate film has a fused portion where the edges are overlapped and the inner surface is fused together, the laminate film has a fused portion side surface where the fused portion is formed, an opposite side facing the fused portion side surface, and a pair of main surfaces perpendicular to the fused portion side surface and the opposite side surface, and having a larger area than the fused portion side surface and the opposite side surface, and the laminate film has an uneven shape on at least one of the fused portion side surface and the opposite side surface.

Description

Technical Field

[0001] The present disclosure relates to a laminated battery.

Background Art

[0002] There has been a conventional study on a laminated battery in which battery elements such as an electrode body are covered and encapsulated with a laminated film, and the ends of the laminated film are overlapped with each other to have a fusion part where the inner surfaces are fused.

[0003] For example, in Patent Document 1, both electrodes of a power generation element for a battery are drawn out to the outside, the power generation element for a battery is sandwiched from above and below by a concavo-convex plate material which is an internal member, the whole is wrapped with a sheet material, and the ends of the sheet material are hermetically joined and sealed by heat welding or the like. The concavo-convex plate material is a single-sided concavo-convex plate, has concavo-convex portions on the surface opposite to the surface sandwiching the power generation element for a battery, and the sheet material also has concavo-convex portions corresponding to the concavo-convex portions of the concavo-convex plate material. By combining these concavo-convex portions, a sheet material type battery in which convex portions and concave portions are formed on the upper and lower side surfaces of the sheet material type battery is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] ​Incidentally, when forming a fused joint where the edges of laminate films overlap and their inner surfaces are fused, a method is employed to improve airtightness by placing the battery elements covered with laminate film into a reduced-pressure space and heat-fusing the overlapping edges of the laminate film under reduced pressure to form the fused joint. However, when the laminate-type battery is removed from the reduced-pressure space after the fused joint has been formed and released from the reduced-pressure state, the sides and opposite sides of the fused joint of the laminate film may sag, reducing the structural efficiency of the battery.

[0006] This disclosure is made in view of the above circumstances and aims to provide a laminate-type battery that can improve the structural efficiency of the battery. [Means for solving the problem]

[0007] The means for solving the above problems include the following embodiments. <1> Battery elements, It comprises a laminate film that covers and encloses the aforementioned battery element, The laminate film has a fused portion where the edges are overlapped and the inner surfaces are fused together. The laminate film has a side surface of the fusion portion where the fusion portion is formed, a side surface opposite to the side surface of the fusion portion, and a pair of main surfaces perpendicular to the side surface of the fusion portion and the opposite side, and having a larger area than the side surface of the fusion portion and the opposite side. The laminate film has an uneven surface on at least one of the side surface of the fused portion and the opposite side, forming a laminate-type battery. <2> The laminate film has the aforementioned uneven shape on the opposite side. <1> Laminated batteries as described above. <3> The laminate film has at least one of the side surface of the fused portion and the opposite side. The material has an uneven shape in which recesses and protrusions are repeated from one main surface side toward the other main surface side, <1> or <2> Laminated batteries as described above. <4> The laminate film has the uneven shape on the entire surface of at least one of the side surface of the fused portion and the opposite side. <1> ~ <3> A laminated battery as described in any one of the items. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a laminated battery that can improve the structural efficiency of the battery. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view illustrating a laminated battery according to an embodiment of the present disclosure. [Figure 2] This is a schematic cross-sectional view illustrating a conventional laminated battery. [Figure 3] This is a schematic plan view showing the main parts of the vehicle. [Figure 4] This is a schematic perspective view of the battery module. [Figure 5] This is a plan view of the battery module with the top cover removed. [Figure 6] This is a schematic diagram showing a battery cell housed in a battery module, viewed from the thickness direction. [Modes for carrying out the invention]

[0010] <Laminated battery> A laminated battery according to an embodiment of the present disclosure comprises a battery element and a laminate film that covers and encloses the battery element. The laminate film has a fused portion where the edges overlap and the inner surface is fused together, and the laminate film also has a fused portion side surface where the fused portion is formed, an opposite side facing the fused portion side surface, and a pair of main surfaces perpendicular to the fused portion side surface and the opposite side surface, and having a larger area than the fused portion side surface and the opposite side surface. Furthermore, the laminate film has an uneven shape on at least one of the fused portion side surface and the opposite side surface.

[0011] Hereinafter, an embodiment of a laminate-type battery according to the present disclosure will be described with reference to the drawings. The following figures are shown schematically, and the sizes and shapes of each part are exaggerated as appropriate for ease of understanding.

[0012] FIG. 1 is a schematic cross-sectional view illustrating a laminate battery according to an embodiment of the present disclosure. Note that the upper FIG. 1(a) represents the laminate battery before being released from the reduced-pressure state when forming the fusion part on the laminate film, and the lower FIG. 1(b) represents the laminate battery after being released from the reduced-pressure state when forming the fusion part on the laminate film.

[0013] The laminate battery 20 shown in FIG. 1(a) has an electrode body 5 as an example of a battery element formed in a substantially rectangular plate shape, and a laminate film 28 that covers and encloses the electrode body 5. The laminate film 28 has a fusion part 28A where the ends are overlapped and the inner surfaces are fused, and the inside of the laminate film 28 is sealed by the fusion part 28A. The laminate film 28 has four surfaces: a fusion part side surface 20A disposed on the side where the fusion part 28A is formed, an opposite side surface 20B opposite to the fusion part side surface 20A, and a pair of main surfaces 20C and 20D that are orthogonal to the fusion part side surface 20A and the opposite side surface 20B and have a larger area than the fusion part side surface 20A and the opposite side surface 20B. Note that the main surfaces 20C and 20D are surfaces that become the stacking direction when a plurality of laminate batteries 20 are further stacked to form a battery stack. And the laminate film 28 has an uneven shape 20X on the opposite side surface 20B.

[0014] In the laminate battery according to the embodiment of the present disclosure, by having an uneven shape on the opposite side surface of the laminate film, the structural efficiency of the battery can be enhanced.

[0015] Here, a method for forming a fusion part on a laminate film in a conventional laminate battery will be described with reference to FIG. 2. FIG. 2 is a schematic cross-sectional view illustrating a conventional laminate battery. The upper FIG. 2(a) represents the laminate battery before being released from the reduced-pressure state when forming the fusion part on the laminate film, and the lower FIG. 2(b) represents the laminate battery after being released from the reduced-pressure state when forming the fusion part on the laminate film. The laminate battery 200 shown in FIG. 2(a) has an electrode body 5 formed in a substantially rectangular plate shape and a laminate film 228 that covers and encapsulates the electrode body 5. The laminate film 228 has a fusion part 228A where the ends are overlapped and the inner surfaces are fused. The laminate film 228 has four surfaces: a fusion part side surface 200A disposed on the side where the fusion part 228A is formed, an opposite side surface 200B facing the fusion part side surface 200A, and a pair of main surfaces 200C and 200D that are orthogonal to the fusion part side surface 200A and the opposite side surface 200B and have a larger area than the fusion part side surface 200A and the opposite side surface 200B. Note that the laminate film 228 has no concavo-convex shape on either the fusion part side surface 200A or the opposite side surface 200B.

[0016] In this laminate battery 200, when forming the fusion part 228A on the laminate film 228, first, the electrode body 5 is covered with the laminate film 228, and the ends of the laminate film 228 are overlapped. Next, the electrode body 5 and the laminate film 228 are placed in a reduced-pressure space, and the overlapped part of the ends of the laminate film 228 is thermally fused in the reduced-pressure state to form the fusion part 228A. Since the electrode bodies 5 generally have dimensional differences for each individual, the laminate film 228 usually has dimensions with a margin relative to the size of the electrode body 5. Therefore, by performing thermal fusion on the laminate film 228 in the state of being disposed in the reduced-pressure space as described above, the sealing performance between the laminate film 228 and the electrode body 5 can be enhanced. However, when the laminated battery 200 was removed from the reduced pressure space after the fusion portion 228A was formed and released from the reduced pressure state, a pressure difference occurred between the inside and outside of the laminate film 228, which sometimes caused the laminate film 228 to sag 200X on the opposite side 200B. When sagging 200X occurred, the opposite side 200B of the laminate film 228 became curved, as shown in Figure 2, and as a result, the position of the edge of the opposite side 200B sometimes widened from position a to position b. In the case of conventional laminated batteries 200, it was anticipated that sagging 200X would occur on the opposite side 200B of the laminate film 228, causing it to become curved, and the position of the wall 210 of the battery case housing the laminated battery 200 was designed to be further out than position b shown in Figure 2. In other words, a deflection 200X occurred on the opposite side 200B of the laminate film 228, causing it to become curved, which sometimes reduced structural efficiency. Furthermore, deflection in the laminate film 228 can occur not only on the opposite side 200B but also on the side 200A of the fused portion.

[0017] In contrast, the laminated battery according to the embodiment of this disclosure has an uneven surface on at least one of the fused portion side and the opposite side of the laminate film. Therefore, even when the laminated battery is removed from the reduced pressure space after the fused portion has been formed and released from the reduced pressure state, causing a pressure difference between the inside and outside of the laminate film, deflection of the laminate film on the opposite side and the fused portion side is suppressed. In other words, the deflection that would otherwise occur is absorbed by the uneven surface, making it less prone to deflection. Therefore, as shown in Figure 1, for example, the position of the end of the opposite side 20B after the reduced pressure state is released can be suppressed to the extent that it extends from position c to position d, compared to the conventional laminated battery shown in Figure 2. As a result, the position of the wall 210 of the battery case housing the laminated battery 20 can be shifted in the direction of arrow S compared to the case housing the conventional laminated battery shown in Figure 2, thereby improving the structural efficiency of the battery.

[0018] Thus, according to the laminated battery embodiment of this disclosure, the structural efficiency of the battery is improved. It is possible to do so.

[0019] Figure 1 shows an embodiment in which the laminate film 28 has an uneven shape 20X on the opposite side 20B (the side facing the fusion portion side 20A), but the laminate-type battery according to the embodiment of this disclosure is not limited to this. In other words, the fusion portion side 20A in Figure 1 may have an uneven shape, or both the fusion portion side 20A and the opposite side 20B may have an uneven shape. Although deflection in the laminate film can occur on the fusion portion side, having an uneven shape on the fusion portion side 20A suppresses the occurrence of this deflection on the fusion portion side. However, in the laminated battery according to the embodiment of this disclosure, it is preferable that at least the side opposite to the laminate film has an uneven shape, from the viewpoint of making it easier to improve the structural efficiency of the battery.

[0020] Figure 1 shows an embodiment of a laminate film 28 having an uneven surface shape in which recesses and protrusions are repeated from one main surface 20C to the other main surface 20D (i.e., from top to bottom in Figure 1). However, the laminate battery according to the embodiment of this disclosure is not limited to this. In other words, it may have an uneven surface shape in which recesses and protrusions are repeated in a direction perpendicular to the direction from one main surface 20C to the other main surface 20D (i.e., the depth direction in Figure 1). However, in the laminated battery according to the embodiment of this disclosure, it is preferable that the laminated battery has an uneven shape in which recesses and protrusions are repeated from one main surface 20C to the other main surface 20D (i.e., from top to bottom in Figure 1), from the viewpoint of making it easier to improve the structural efficiency of the battery.

[0021] Figure 1 shows an embodiment in which the entire surface of the opposite side 20B has an uneven shape 20X, but the laminated battery according to the embodiment of this disclosure is not limited to this. In other words, the uneven shape may be formed only on a part of the opposite side 20B of the laminate film 28. For example, the laminate film 28 may have an uneven shape only in the region on the main surface 20C side of the opposite side 20B, or it may have an uneven shape only in the region on the other main surface 20D side of the opposite side 20B. Alternatively, it may have an uneven shape only in the middle region (i.e., no uneven shape is formed in the regions on the main surface 20C side and the main surface 20D side). Furthermore, the uneven shape may also be formed only on a part of the direction perpendicular to the direction from one main surface 20C side to the other main surface 20D side (i.e., the depth direction in Figure 1). The same applies when the laminate film has an uneven shape on the side surface of the fused portion; the uneven shape may be formed only on a portion of the side surface of the fused portion of the laminate film in the direction from one main surface 20C to the other main surface 20D (i.e., the vertical direction in Figure 1). Furthermore, the uneven shape may also be formed only on a portion of the side surface of the fused portion of the laminate film in the direction perpendicular to the direction from one main surface 20C to the other main surface 20D (i.e., the depth direction in Figure 1). However, in the laminated battery according to the embodiment of this disclosure, it is preferable that the laminate film has an uneven shape on at least one of the sides of the fused portion and the opposite side, from the viewpoint of making it easier to improve the structural efficiency of the battery.

[0022] Figure 1 shows an embodiment in which a bumpy shape is formed on the opposite side 20B having three convex portions and three concave portions, but the laminate-type battery according to the embodiment of this disclosure is not limited to this. The bumpy shape that the laminate film has on at least one of the side surface of the fusion portion and the opposite side only needs to have at least one convex portion and one concave portion. Furthermore, from the viewpoint of making it easier to improve the structural efficiency of the battery, it is preferable that the bumpy shape formed on at least one of the side surface of the fusion portion and the opposite side of the laminate film has three or more convex portions and three or more concave portions, and it is preferable that it has five or more convex portions and five or more concave portions. Preferably, the surface has a convex shape with 10 or more protrusions and 10 or more recesses. There is no particular upper limit to the number of protrusions and recesses, but for example, the surface may have 30 or fewer protrusions and 30 or fewer recesses.

[0023] Next, a battery module, a battery pack, and a vehicle having a laminated battery according to an embodiment of the present disclosure will be described with reference to the figures. The laminated battery according to an embodiment of the present disclosure is used as the battery cell shown in Figures 5 and 6 below.

[0024] (Overall configuration of vehicle 100) Figure 3 is a schematic plan view showing the main parts of a vehicle 100 to which the battery pack 10 according to the embodiment is applied. As shown in Figure 3, the vehicle 100 is an electric vehicle (BEV: Battery Electric Vehicle) with the battery pack 10 mounted under the floor. Note that the arrows UP and FR in each figure indicate UP and FR. The arrows LH and R indicate the upper side in the vehicle's vertical direction, the front side in the vehicle's longitudinal direction, and the left side in the vehicle's width direction, respectively. When explaining using the directions of front, rear, left, right, up, and down, unless otherwise specified, they refer to the front and rear in the vehicle's longitudinal direction, the left and right in the vehicle's width direction, and the up and down in the vehicle's vertical direction.

[0025] In this embodiment, the vehicle 100, as an example, has a DC / DC converter 102, an electric compressor 104, and a PTC (Positive Temperature Coefficient) heater 106 positioned in front of the battery pack 10. The motor 108, gearbox 110, inverter 112, and charger 114 are positioned behind the battery pack 10.

[0026] The DC current output from the battery pack 10 is voltage-adjusted by the DC / DC converter 102 and then supplied to the electric compressor 104, PTC heater 106, inverter 112, etc. Power is also supplied to the motor 108 via the inverter 112, causing the rear wheels to rotate and the vehicle 100 to move.

[0027] A charging port 116 is provided on the right side of the rear of the vehicle 100. By connecting a charging plug from an external charging device (not shown) to the charging port 116, power can be stored in the battery pack 10 via the onboard charger 114.

[0028] The arrangement and structure of the components constituting the vehicle 100 are not limited to the configuration described above. For example, it may be applied to a hybrid vehicle (HV) or a plug-in hybrid electric vehicle (PHEV) equipped with an engine. In this embodiment, the motor 108 is mounted at the rear of the vehicle and it is a rear-wheel drive vehicle, but it is not limited to this, and 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 for each wheel.

[0029] Here, the battery pack 10 is composed of multiple battery modules 11. In this embodiment, as an example, 10 battery modules 11 are provided. Specifically, 5 battery modules 11 are arranged in the longitudinal direction of the vehicle on the right side of the vehicle 100, and 5 battery modules 11 are arranged in the longitudinal direction of the vehicle on the left side of the vehicle 100. Furthermore, each battery module 11 is electrically connected.

[0030] Figure 4 is a schematic perspective view of the battery module 11. As shown in Figure 4, the battery module 11 is formed in a roughly rectangular parallelepiped shape with the vehicle width direction as the longitudinal direction. The outer shell of the battery module 11 is made of aluminum alloy. For example, the outer shell of the battery module 11 is formed by joining aluminum die-cast parts to both ends of an aluminum alloy extruded material by laser welding or the like.

[0031] 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, which will be described later, is connected to the connector 14. In addition, busbars (not shown) are welded to both ends of the battery module 11 in the vehicle width direction.

[0032] 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.

[0033] Figure 5 is a plan view of the battery module 11 with the top cover removed. As shown in Figure 5, multiple battery cells 20 are housed inside the battery module 11 in an arranged state. In this embodiment, as an example, 24 battery cells 20 are arranged in the front-rear direction of the vehicle and bonded to each other.

[0034] On top of the battery cell 20 is a flexible printed circuit board (FPC). A flexible printed circuit board 22 is positioned. The flexible printed circuit board 22 is formed in a strip shape with the vehicle width direction as its longitudinal direction, and thermistors 24 are provided at both ends of the flexible printed circuit board 22. The thermistors 24 are not bonded to the battery cell 20, but are pressed toward the battery cell 20 by the upper cover of the battery module 11.

[0035] Furthermore, one or more cushioning materials (not shown) are housed inside the battery module 11. For example, the cushioning material is a thin, elastically deformable plate-like member, and is arranged between adjacent battery cells 20 with the arrangement direction of the battery cells 20 as the thickness direction. In this embodiment, as an example, cushioning material is arranged at both ends in the longitudinal direction and in the longitudinal center of the battery module 11.

[0036] Figure 6 is a schematic view of a battery cell 20 housed in a battery module 11, viewed from the thickness direction. As shown in Figure 6, the battery cell 20 is formed in a roughly rectangular plate shape, and an electrode body (not shown) is housed inside. The electrode body is composed of a positive electrode, a negative electrode, and a separator stacked together, and is sealed with a laminate film 28.

[0037] In this embodiment, as an example, the electrode housing is formed by folding and bonding an embossed sheet-like laminate film 28. While both a single-cup embossed structure with one embossed area and a double-cup embossed structure with two embossed areas can be employed, this embodiment uses a single-cup embossed structure with a fold depth of approximately 8mm to 10mm.

[0038] The upper ends of both longitudinal sides of the battery cell 20 are bent, and the corners form the outer shape. In addition, the upper end of the battery cell 20 is bent, and a fixing tape 30 is wrapped around the upper end of the battery cell 20 along its longitudinal direction.

[0039] Here, terminals (tabs) 26 are provided at both longitudinal ends of the battery cell 20. In this embodiment, as an example, the terminals 26 are provided at a position offset below the vertical center of the battery cell 20. The terminals 26 are joined to a busbar (not shown) by laser welding or the like.

[0040] The length CW1 of the battery cell 20 in the vehicle width direction is, for example, 530mm to 600mm, the length CW2 of the area where the electrode body is housed is, for example, 500mm to 520mm, and the height CH of the battery cell 20 is, for example, 80mm to 110mm. The thickness is 7.0mm to 9.0mm, and the height TH of terminal 26 is 40mm to 50mm. [Explanation of Symbols]

[0041] 5 Electrode body, 20A, 200A Side of fusion joint, 20B, 200B Opposite side, 20C, 20D, 200C, 200D Main surface, 20X Uneven shape, 28A, 228A Fusion joint, 200X Deflection, 210 Battery case wall, 10 Battery pack, 11 Battery module, 12 Voltage terminal, 14 Connector, 20, 200 Battery cell (laminated battery), 22 Flexible printed circuit board, 24 Thermistor, 26 Terminal, 28, 228 Laminate film, 30 Fixing tape, 100 Vehicle, 102 Converter, 104 Electric compressor, 106 Heater, 108 Motor, 110 Gearbox, 112 Inverter, 114 Onboard charger, 114 Charger, 116 Charging port

Claims

1. Battery elements, It comprises a laminate film that covers and encloses the aforementioned battery element, The laminate film has a fused portion where the edges are overlapped and the inner surfaces are fused together. The laminate film has a side surface of the fusion portion where the fusion portion is formed, a side surface opposite to the side surface of the fusion portion, and a pair of main surfaces perpendicular to the side surface of the fusion portion and the opposite side, and having a larger area than the side surface of the fusion portion and the opposite side. The laminate film has an uneven surface on at least one of the side surface of the fused portion and the opposite side, forming a laminate-type battery.

2. The laminate battery according to claim 1, wherein the laminate film has the uneven shape on the opposite side.

3. The laminate battery according to claim 1, wherein the laminate film has the uneven shape on at least one of the side surface of the fused portion and the opposite side, in which recesses and protrusions are repeated from one main surface side to the other main surface side.

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

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