Manufacturing method for laminated batteries

Abstract

To provide a manufacturing method of a laminate type battery, capable of reducing a difference in thickness generated depending on a place of a lamination film after deposition in contact with a side surface member.SOLUTION: A manufacturing method of a laminate type battery comprising an electrode body, a side surface member, and a laminate film covering the electrode body and the side surface member, the side surface member being arranged at a position inclined to a center of a side surface in a longer direction of the side surface, includes a deposition step of depositing the laminate film so as to cover part of the electrode body and the side surface member. When a region on the side where the side surface member is eccentrically arranged is an uneven side region A and the other region is a non-uneven side region B in the side surface member, with a center of the side surface member in the longer direction of the side surface as a boundary, a mean thickness a in contact with the uneven side region A of the side surface member is thicker than a mean thickness b of the region in contact with the non-uneven side region B of the side surface member in the laminate film used for the fusion step.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Conventionally, a laminated battery including an electrode body, side members such as terminals, and a laminate film covering part of the electrode body and the side members has been used.

[0003] For example, Patent Document 1 discloses a battery in which a terminal on one side surface is disposed offset to one side with respect to the center of the side surface.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Conventionally, a laminated battery including an electrode body, side members such as terminals, and a laminate film covering part of the electrode body and the side members has been used. And in this laminated battery, the side member may be disposed at a position offset to one side with respect to the center of the side surface in the longitudinal direction of the side surface. However, when the laminate film is welded to the electrode body in which the side member is disposed offset to one side on the side surface, a difference in thickness may occur at some locations in the laminate film in the region contacting the side member.

[0006] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a method for manufacturing a laminated battery capable of reducing the difference in thickness that occurs at some locations in the laminate film after welding to the side member.

Means for Solving the Problems

[0007] The means for solving the above problems include the following embodiments. <1> Electrode body and A side member arranged on the side of the electrode body, The device comprises a laminate film that covers the electrode body and a part of the side member, A method for manufacturing a laminated battery, wherein the side member is positioned in the longitudinal direction of the side at a location offset to one side with respect to the center of the side, The process includes a welding step of welding the laminate film so as to cover a portion of the electrode body and the side member, In the aforementioned side member, if the region on the side where the side member is unevenly arranged is defined as the unevenly arranged region A, with the center of the side member in the longitudinal direction of the side as the boundary, and the other region is defined as the non-unevenly arranged region B, A method for manufacturing a laminated battery, wherein the laminate film used in the welding process has an average thickness a in the region of the side member that is in contact with the unevenly distributed region A, and the average thickness b in the region of the side member that is in contact with the non-unevenly distributed region B. <2> The laminate film used in the welding process has a thickness in the region in contact with the side member that increases continuously toward the side where the side member is positioned unevenly in the longitudinal direction of the side. <1> A method for manufacturing laminated batteries as described above. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a method for manufacturing a laminated battery that can reduce the difference in thickness that occurs in different locations in the laminated film after welding that is in contact with the side members. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic perspective view showing the electrode body and side member before the welding process in a manufacturing method of a laminated battery according to an embodiment of the present disclosure. [Figure 2]This is a schematic side view, seen from the side, showing the state before welding is performed in the welding process in the manufacturing method of a laminate-type battery according to the embodiment of this disclosure. [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] An example of an embodiment of this disclosure will be described. These descriptions are illustrative of embodiments and do not limit the scope of the invention. Furthermore, the term "process" includes not only independent processes, but also any process that cannot be clearly distinguished from other processes, as long as its intended function is achieved.

[0011] <Manufacturing method for laminated batteries> A method for manufacturing a laminated battery according to an embodiment of the present disclosure comprises an electrode body, a side member disposed on the side of the electrode body, and a laminate film covering the electrode body and a part of the side member, wherein the side member is positioned offset to one side with respect to the center of the side in the longitudinal direction of the side. This manufacturing method includes a step of welding a laminate film to cover part of the electrode body and the side member. Furthermore, in the side member, if the region on the side where the side member is unevenly arranged is defined as the unevenly arranged region A, with the center of the side member in the longitudinal direction of the side as the boundary, and the other region as the non-unevenly arranged region B, then the average thickness a of the laminate film used in the welding process is greater in the region in contact with the unevenly arranged region A of the side member than in the average thickness b of the region in contact with the non-unevenly arranged region B of the side member.

[0012] Here, a method for manufacturing a laminated battery according to an embodiment of the present disclosure will be described with reference to the drawings. Each of the figures shown below is schematically illustrated, and the size and shape of each part are exaggerated as appropriate for easy understanding.

[0013] FIG. 1 is a schematic perspective view showing an electrode body and a side member before performing a welding process in a method for manufacturing a laminated battery according to an embodiment of the present disclosure. FIG. 2 is a schematic side view seen from the side direction (the direction of the surface on which the side member is disposed, the Z direction in FIG. 2) showing a state before welding in the welding process in a method for manufacturing a laminated battery according to an embodiment of the present disclosure.

[0014] As shown in FIG. 1, in a method for manufacturing a laminated battery according to an embodiment of the present disclosure, an electrode body 4 used in the welding process (that is, before performing the welding process) has terminals 26 as an example of side members respectively disposed on a pair of side surfaces 4A thereof. Note that on the side surface 4A of the electrode body 4, there are two regions 41A and 42A where the terminals 26 are not disposed on both sides of the terminal 26 in the longitudinal direction (arrow X direction) of the side surface 4A. The terminal 26 is disposed at a position offset to one side with respect to the center Lc1 of the side surface 4A in the longitudinal direction (arrow X direction) of the side surface 4A of the electrode body 4 (offset to the right direction in FIGS. 1 and 2). Therefore, on the side surface 4A of the electrode body 4, the region 42A where the terminal 26 is not disposed on the side where the terminal 26 is disposed offset has a larger area than the other side, and the region 41A on the other side has a smaller area. Hereinafter, among the two regions where the side member is not disposed on the side surface of the electrode body, the region with a larger area will be referred to as the "wide region", and the region with a smaller area will be referred to as the "narrow region".

[0015] And in the welding process in the method for manufacturing a laminated battery according to an embodiment of the present disclosure, as shown in FIG. 2, a laminate film 28 is disposed so as to cover the electrode body 4 and a part of the terminal 26. Note that FIG. 2 shows the state before welding in the welding process. The laminate film 28 is disposed so as to cover the entire surface of the electrode body 4, and all regions where the terminal 26 is not provided on the side surface 4A of the electrode body 4 are covered with the laminate film 28 (therefore, in FIG. 2, the electrode body 4 covered with the laminate film 28 is shown by a dotted line). Further, the laminate film 28 is disposed so as to cover a part of each of the upper surface 26B, one side surface 26C, the lower surface 26D, and the other side surface 26E of the terminal 26, more specifically, the regions on the electrode body 4 side of these four surfaces. Accordingly, the entire outer surface 26A of the terminal 26, and the regions on the opposite side of the electrode body 4 on the upper surface 26B, one side surface 26C, the lower surface 26D, and the other side surface 26E are not covered with the laminate film 28 and are in an exposed state.

[0016] And in the laminate film 28 used in the welding process (that is, before the welding process is performed), a difference in thickness is provided depending on the location. Here, in the terminal 26, with the center Lc2 of the terminal 26 in the longitudinal direction of the side surface 4A (arrow X direction) as a boundary, the region on the side where the terminal 26 is disposed offset (that is, the narrow region 42A side) is defined as the uneven region A, and the region on the side opposite to the side where the terminal 26 is disposed offset (that is, the wide region 41A side) is defined as the non-uneven region B. In this case, in the laminate film 28 used in the welding process, the average thickness a of the region in contact with the uneven region A of the terminal 26 is greater than the average thickness b of the region in contact with the non-uneven region B of the terminal 26.

[0017] In this disclosure, the average thickness a of the laminate film in the region in contact with the unevenly distributed region A of the side member means the average thickness of the laminate film in the region in contact with the unevenly distributed region A on two surfaces parallel to the longitudinal direction of the side of the electrode body (the upper surface 26B and the lower surface 26D of the terminal 26 in Figure 1), out of the four surfaces on the side member with which the laminate film is in contact (in Figure 1, the upper surface 26B and the lower surface 26D of the terminal 26). Furthermore, the average thickness b of the region of the laminate film that is in contact with the non-eccentric region B of the side member refers to the average thickness of the laminate film in the region that is in contact with the non-eccentric region B on two of the four surfaces of the side member that the laminate film is in contact with, which are parallel to the longitudinal direction of the side of the electrode body.

[0018] Thus, in the method for manufacturing a laminated battery according to the embodiment of this disclosure, the average thickness a of the laminate film used in the welding process is greater than the average thickness b of the region in contact with the non-uniform region B of the side member. This configuration makes it possible to reduce the thickness differences that occur in different locations in the laminate film after welding that is in contact with the side member.

[0019] Conventionally, laminated batteries have been used, which comprise an electrode body, side members such as terminals, and a laminate film that covers part of the electrode body and side members. In these laminated batteries, depending on the arrangement of the batteries within the battery module, the side members may be positioned off-center to one side in the longitudinal direction of the side (the X direction in Figures 1 and 2).

[0020] In the manufacturing of laminate-type batteries, when sealing the electrode body and a portion of the side member with a laminate film, a process is carried out to weld the laminate film so as to cover the electrode body and a portion of the side member. For example, at the point where the laminate film contacts the side member, a heated welding member is pressed against the side member through the laminate film, melting the inner surface of the laminate film (the side in contact with the side member) and welding the laminate film to the side member.

[0021] However, when a laminate film was welded to an electrode body in which the side members were biased to one side on the side, differences in thickness sometimes occurred in the laminate film in the area in contact with the side members. Specifically, in the laminate film in the area in contact with the side members, the thickness of the laminate film was thinner in the biased side area A (i.e., the narrow area side (the area on the 42A side in Figures 1 and 2)), while the thickness of the laminate film was thicker in the non-biased side area B (i.e., the wide area side (the area on the 41A side in Figures 1 and 2)). The reason is presumably as follows: When a laminate film is welded to a side member, the heat applied to the laminate film is also absorbed by the side member and the electrode body. Therefore, not all of the applied heat contributes to the melting of the inner surface of the laminate film. Furthermore, in electrode bodies where the side member is positioned unevenly on one side of the electrode body, it is thought that there will be a difference in the amount of heat absorbed by the electrode body on one side of the side member and the other side in the longitudinal direction of the side (the X direction in Figures 1 and 2). In other words, on the side of the electrode body, it is thought that the amount of heat absorbed by the electrode body will be greater on the side member closer to a wide area (i.e., the non-uneven side area B) when welding the laminate film, and less on the side member closer to a narrow area (i.e., the uneven side area A). This is presumed to be because the volume of electrodes contributing to heat absorption in the wider region (i.e., the volume of electrodes near the non-eccentric region B of the side member) is larger than the volume of electrodes contributing to heat absorption in the narrower region (i.e., the volume of electrodes near the eccentric region A of the side member). Consequently, in the laminate film in contact with the non-eccentric region B of the side member, the amount of heat absorbed by the electrodes is large, resulting in less heat contributing to the melting of the inner surface of the laminate film. This reduces the amount of melting, leading to a thicker laminate film after welding. On the other hand, in the laminate film in contact with the eccentric region A of the side member, the amount of heat absorbed by the electrodes is small, resulting in more heat contributing to the melting of the inner surface of the laminate film. This increases the amount of melting, leading to a thinner laminate film after welding. Based on the above mechanism, it is presumed that differences in thickness occur in the laminate film after welding in the region in contact with the side member.

[0022] Therefore, in the manufacturing method of a laminate-type battery according to the embodiment of this disclosure, the average thickness a of the region in contact with the unevenly distributed region A of the side member in the laminate film used in the welding process is made thicker than the average thickness b of the region in contact with the non-unevenly distributed region B of the side member. In other words, in the region of the laminate film in contact with the side member, the thickness of the narrow region (right side in Figures 1 and 2) corresponding to the side that becomes thicker after welding (i.e., unevenly distributed region A) is adjusted to be thinner in advance, and the thickness of the wide region (left side in Figures 1 and 2) corresponding to the side that becomes thinner after welding (i.e., non-unevenly distributed region B) is adjusted to be thicker in advance. By adjusting the thickness of the region of the laminate film in contact with the side member in this way, it is possible to offset the difference in thickness in the laminate film after welding caused by the difference in the amount of heat absorbed by the electrode body. As a result, it is possible to reduce the difference in thickness that occurs in different locations in the laminate film after welding that is in contact with the side member.

[0023] In the manufacturing method of the laminated battery according to the embodiment of this disclosure, it is preferable that the thickness of the laminate film used in the welding process in the region in contact with the side member increases continuously toward the side where the side member is unevenly arranged in the longitudinal direction of the side.

[0024] In the laminate film 28 shown in Figure 2, the thickness in the region in contact with the terminals 26 increases continuously in the longitudinal direction of the side surface 4A (the X direction in Figure 2) from the wide region 41A side to the narrow region 42A side (i.e., the side where the terminals 26 are unevenly arranged). Therefore, comparing the thickness of section 28A 28a, section 28B 28b, section 28C 28c, and section 28D 28d in the region of the laminate film 28 in contact with the terminals 26, starting from the side closer to the wide region 41A, the thickness increases in the order of "28a < 28b < 28c < 28d".

[0025] Thus, in the laminate film used in the welding process, the thickness in the region in contact with the side member is continuously thicker towards the side where the side member is unevenly positioned along the longitudinal direction of the side. This makes it possible to further reduce the thickness differences that occur in different locations in the laminate film after welding that is in contact with the side member.

[0026] Here, we will explain a configuration in which the thickness of the laminate film in the region in contact with the side member continuously increases toward the side where the side member is positioned unevenly along the longitudinal direction of the side. The "thickness" referred to here means the thickness of the laminate film in the region in contact with the side member on two surfaces (in Figure 1, the upper surface 26B and the lower surface 26D of the terminal 26) that are parallel to the longitudinal direction of the electrode body's side. Therefore, it is sufficient that the thickness of the laminate film in the region in contact with the side member on the two surfaces (in Figure 1, the upper surface 26B and the lower surface 26D of the terminal 26) that are parallel to the longitudinal direction of the side of the electrode body.

[0027] However, in the manufacturing method of a laminated battery according to the embodiment of this disclosure, the laminate film used in the welding process does not have to have a configuration in which the thickness in the region in contact with the side member increases continuously toward the side where the side member is unevenly arranged in the longitudinal direction of the side. For example, the thickness in the region of the laminate film in contact with the side member may be configured to increase in steps toward the side where the side member is unevenly arranged in the longitudinal direction of the side (i.e., a configuration in which the thickness gradually increases in a step-like manner).

[0028] (Measurement method) Here, we will explain how to measure the average thickness a of the region in contact with the unevenly distributed side region A of the laminate film, and the average thickness b of the region in contact with the non-unevenly distributed side region B of the laminate film. As mentioned above, the average thickness a of the laminate film in the region in contact with the eccentric region A of the side member means the average thickness of the laminate film in the region in contact with the eccentric region A on the two surfaces parallel to the longitudinal direction of the side of the electrode body, out of the four surfaces on which the laminate film contacts the side member. Similarly, the average thickness b of the laminate film in contact with the non-eccentric region B of the side member means the average thickness of the laminate film in the region in contact with the non-eccentric region B on the two surfaces parallel to the longitudinal direction of the side of the electrode body, out of the four surfaces on which the laminate film contacts the side member.

[0029] The average thickness a is calculated by measuring the thickness of the laminate film in the region in contact with the eccentric region A on two of the four surfaces parallel to the longitudinal direction of the electrode body's side surface of the side member, at any 10 locations, and taking the arithmetic mean of these measurements. On the other hand, the average thickness b is calculated by measuring the thickness of the laminate film in the region in contact with the non-eccentric region B on two of the four surfaces parallel to the longitudinal direction of the electrode body's side surface of the side member, at any 10 locations, and taking the arithmetic mean of these measurements.

[0030] Next, a battery module, a battery pack, and a vehicle having a laminate-type battery manufactured by the manufacturing method of a laminate-type battery according to the embodiment of this disclosure will be described with reference to the figures.

[0031] (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 a battery electric vehicle (BEV) with the battery pack 10 mounted under the floor. In each figure, the arrows UP, FR, and LH indicate the upper side in the vertical direction of the vehicle, the front side in the longitudinal direction of the vehicle, and the left side in the width direction of the vehicle, respectively. When describing the directions of front, rear, left, right, up, and down, unless otherwise specified, they refer to the front and rear in the longitudinal direction of the vehicle, the left and right in the width direction of the vehicle, and the up and down in the vertical direction of the vehicle.

[0032] 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.

[0033] 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.

[0034] 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 charger 114.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] A flexible printed circuit board (FPC) 22 is placed on top of the battery cell 20. 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] The length CW1 of the battery cell 20 in the vehicle width direction is, for example, 530mm~600mm, 600mm~700mm, 700mm~800mm, 800~900mm, and 1000mm or more. The length CW2 of the area where the electrode body is housed is, for example, 500mm~520mm, 600mm~700mm, 700mm~800mm, 800~900mm, and 1000mm or more. The height CH of the battery cell 20 is, for example, 80mm~110mm and 110mm~140mm. The thickness of the battery cell 20 is 5.0mm~7.0mm, 7.0mm~9.0mm, and 9.0mm~11.0mm. The height TH of the terminal 26 is 40mm~50mm, 50mm~60mm, and 60mm~70mm. [Explanation of symbols]

[0048] 4 Electrode body, 10 Battery pack, 11 Battery module, 12 Voltage terminal, 14 Connector, 20 Battery cell, 22 Flexible printed circuit board, 24 Thermistor, 26 Terminal, 28 Laminating film, 30 Fixing tape, 41A, 42A area, 100 Vehicle, 102 Converter, 104 Electric compressor, 106 Heater, 108 Motor, 110 Gearbox, 112 Inverter, 114 Charger, 116 Charging port

Claims

1. Electrode body and A side member arranged on the side of the electrode body, The device comprises a laminate film that covers the electrode body and a part of the side member, A method for manufacturing a laminated battery, wherein the side member is positioned in the longitudinal direction of the side at a location offset to one side with respect to the center of the side, The process includes a welding step of welding the laminate film so as to cover a portion of the electrode body and the side member, In the aforementioned side member, if the region on the side where the side member is unevenly arranged is defined as the unevenly distributed region A, with the center of the side member in the longitudinal direction of the side as the boundary, and the other region is defined as the non-unevenly distributed region B, A method for manufacturing a laminated battery, wherein the laminate film used in the welding process has an average thickness a in the region of the side member that is in contact with the unevenly distributed region A, and the average thickness b in the region of the side member that is in contact with the non-unevenly distributed region B.

2. The method for manufacturing a laminated battery according to claim 1, wherein the thickness of the laminate film used in the welding step is continuously increased in the region in contact with the side member toward the side where the side member is unevenly arranged in the longitudinal direction of the side.

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