Method for manufacturing laminated battery

Abstract

The invention relates to a method for manufacturing a laminated battery, which can reduce the thickness difference caused by different parts in a laminated film after being welded in contact with a side surface member. The laminated battery includes an electrode body, a side surface member disposed on a side surface of the electrode body, and a laminated film covering a portion of the side surface member and the electrode body, the side surface member being disposed in a longitudinal direction of the side surface at a position biased toward a first side in the longitudinal direction with respect to a center of the side surface. This method for manufacturing a laminated battery has a deposition step for depositing a laminated film so as to cover a part of a side surface member and an electrode body, and in the side surface member, a region on the first side is defined as a first region with the center of the side surface member in the longitudinal direction of the side surface as a boundary. When a region on a second side, which is the opposite side to the first side, is defined as a second region, the average thickness of a region of the laminated film used in the deposition step, which is in contact with the first region of the side member, is greater than the average thickness of a region of the laminated film, which is in contact with the second region of the side member.

Description

Technical Field

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

[0002] Conventionally, a laminated battery is used which includes an electrode body, side members such as terminals, and a laminate film covering a portion of the side members and the electrode body. In addition, in such a laminated battery, the side members are sometimes arranged at a position offset to one side relative to the center of the side in the long side direction of the side.

[0003] For example, Japanese Patent Application Laid-Open No. 11-283611 discloses a battery in which a terminal of one side surface is arranged offset to one side with respect to the center of the side surface.

[0004] However, when the laminate film is welded to the electrode body in which the side member is arranged offset to one side, the thickness of the laminate film in the region in contact with the side member may vary depending on the location. Summary of the invention

[0005] The present disclosure provides a method for manufacturing a laminated battery, which can reduce a thickness difference caused by different locations in a laminate film after welding in contact with a side member.

[0006] The present disclosure includes the following aspects.

[0007] A first embodiment of the present disclosure relates to a method for manufacturing a laminated battery, the laminated battery comprising an electrode body, a side member arranged on a side of the electrode body, and a laminate film covering a portion of the side member and the electrode body, the side member being arranged in a long side direction of the side at a position biased toward a first side in the long side direction relative to a center of the side member, wherein the method for manufacturing the laminated battery has a welding step, in which the laminate film is welded in a manner covering a portion of the side member and the electrode body, and in the side member, when a region on the first side is set as a first region and a region on the opposite side, that is, a second side, is set as a second region with the center of the side member in the long side direction of the side as a boundary, an average thickness of a region of the laminate film used in the welding step that is in contact with the first region of the side member is thicker than an average thickness of a region of the laminate film that is in contact with the second region of the side member.

[0008] A second aspect of the present disclosure is the method for manufacturing a laminated battery according to the first aspect, wherein a thickness of a region of the laminate film used in the welding step that is in contact with the side member continuously increases toward the first side in the longitudinal direction of the side surface.

[0009] A third aspect of the present disclosure is the method for manufacturing a laminated battery according to the first aspect, wherein a thickness of a region of the laminate film used in the welding step that contacts the side member gradually increases toward the first side in the longitudinal direction of the side surface.

[0010] According to the present disclosure, it is possible to provide a method for manufacturing a laminated battery capable of reducing a difference in thickness caused by different locations in a laminate film after welding in contact with a side member. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic perspective view showing an electrode body and side members before a welding step is performed in a method for manufacturing a laminated battery according to an embodiment of the present disclosure.

[0012] Figure 2 This is a schematic side view showing a state before welding in a welding step in a method for manufacturing a laminated battery according to an embodiment of the present disclosure, as seen from a side direction.

[0013] Figure 3 It is a schematic plan view showing the main parts of the vehicle.

[0014] Figure 4 This is a schematic perspective view of a battery module.

[0015] Figure 5 This is a top view of the battery module with the upper cover removed.

[0016] Figure 6 This is a schematic diagram of battery cells housed in a battery module as viewed from the thickness direction. DETAILED DESCRIPTION

[0017] An embodiment as an example of the present disclosure will be described. These descriptions are for illustrating the embodiment and do not limit the scope of the invention.

[0018] It should be noted that the term "process" does not only refer to an independent process, but also includes a process that cannot be clearly distinguished from other processes as long as the intended effect of the process can be achieved.

[0019] <Method for manufacturing laminated battery>

[0020] A method for manufacturing a laminated battery according to an embodiment of the present disclosure manufactures a laminated battery comprising: an electrode body, a side member arranged on the side of the electrode body, and a laminate film covering a portion of the side member and the electrode body, wherein the side member is arranged at a position biased to one side relative to the center of the side in the long side direction of the side.

[0021] This manufacturing method includes a step of welding a laminate film so as to cover a part of the side member and the electrode body.

[0022] Moreover, in the side component, when the area on one side where the side component is biasedly arranged is set as the biased side area and the area on the other side is set as the non-biased side area with the center of the side component in the long side direction of the above-mentioned side as the boundary, the average thickness of the area of ​​the laminate film used in the welding process that is connected to the biased side area of ​​the side component is thicker than the average thickness of the area that is connected to the non-biased side area of ​​the side component.

[0023] Here, a method for manufacturing a laminated battery according to an embodiment of the present disclosure will be described using the drawings.

[0024] Each of the drawings shown below is a schematic diagram, and the size and shape of each part are exaggerated appropriately for easy understanding.

[0025] Figure 1 This is a schematic perspective view showing an electrode body and side members before a welding step is performed in a method for manufacturing a laminated battery according to an embodiment of the present disclosure. Figure 2 The laminated battery manufacturing method according to the embodiment of the present disclosure shows a state before welding in the welding step, viewed from the side direction (the direction of the surface where the side member is arranged, Figure 2 A schematic side view of the device as viewed in the Z direction.

[0026] like Figure 1 As shown, in the manufacturing method of the laminated battery of the embodiment of the present disclosure, the electrode body 4 used in the welding process (i.e. before the welding process is performed) has terminals 26 as an example of side members respectively arranged on a pair of side surfaces 4A thereof. It should be noted that, on the side surface 4A of the electrode body 4, there are two areas 41A and 42A where the terminals 26 are not arranged on both sides in the long side direction (arrow X direction) of the side surface 4A, sandwiching the terminals 26.

[0027] One side of the side surface 4A in the longitudinal direction is defined as the first side, and the other side is defined as the second side. The terminal 26 is disposed at a position offset to the first side (at the position of 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. Figure 1 as well as Figure 2 Therefore, in the side surface 4A of the electrode body 4, the area of ​​the region 42A on the first side (the side where the terminal 26 is arranged offset) is smaller than the area of ​​the region 41A on the second side.

[0028] In the following, of the two regions on the side of the electrode body where no side member is arranged, the region with a larger area is referred to as a “wide region”, and the region with a smaller area is referred to as a “narrow region”.

[0029] Furthermore, in the welding step in the method for manufacturing a laminated battery according to an embodiment of the present disclosure, Figure 2 As shown, the laminate film 28 is arranged so as to cover a portion of the terminal 26 and the electrode body 4. It should be noted that Figure 2 The laminate film 28 is arranged to cover the entire surface of the electrode body 4, and the area of ​​the side surface 4A of the electrode body 4 where the terminal 26 is not provided is completely covered by the laminate film 28 (therefore, Figure 2 The electrode body 4 covered by the laminate film 28 is indicated by a dotted line in the figure. In addition, the laminate film 28 is arranged relative to the terminal 26 to cover a portion of each of the upper surface 26B, the left side surface 26C (a side surface along the arrow Y direction as the short side direction of the side surface of the electrode body), the lower surface 26D, and the right side surface 26E (the other side surface along the arrow Y direction as the short side direction of the side surface of the electrode body) of the terminal 26, more specifically, the region on the electrode body 4 side of these four surfaces. Therefore, the entire surface of the outer side surface 26A of the terminal 26 and the region on the side opposite to the electrode body 4 of the upper surface 26B, the left side surface 26C, the lower surface 26D, and the right side surface 26E are not covered by the laminate film 28 and are exposed.

[0030] Moreover, in the laminate film 28 used in the welding process (i.e. before the welding process is performed), the thickness is set to be different depending on the location. Here, in the terminal 26, the center Lc2 of the terminal 26 in the long side direction (arrow X direction) of the side 4A is used as a boundary, and the area on the first side (i.e., the narrow area side) is set as the first area A (offset side area), and the area on the side opposite to the first side, i.e., the second side (i.e., the wide area side) is set as the second area B (non-offset side area). In this case, for the laminate film 28 used in the welding process, the average thickness a of the area connected to the first area A of the terminal 26 is thicker than the average thickness b of the area connected to the second area B of the terminal 26.

[0031] It should be noted that, in the present disclosure, the average thickness a of the region in contact with the first region A of the side member in the laminated film refers to the average thickness a of the four surfaces in contact with the laminated film in the side member (in Figure 1 The two surfaces (in the four surfaces of the upper surface 26B, the left side surface 26C, the lower surface 26D and the right side surface 26E of the terminal 26) parallel to the long side direction of the side surface of the electrode body are Figure 1 ΔV is the average thickness of the laminate film in the region that is in contact with the first region A in both the upper surface 26B and the lower surface 26D of the terminal 26.

[0032] In addition, the average thickness b of the area in the laminate film that is connected to the second area B of the side component refers to the average thickness of the laminate film in the area that is connected to the second area B on two surfaces parallel to the long side direction of the side of the electrode body among the four surfaces in which the laminate film is connected in the side component.

[0033] Thus, in the manufacturing method of the laminated battery of the embodiment of the present disclosure, in the laminate film used in the welding step, the average thickness a of the region in contact with the first region A of the side member is thicker than the average thickness b of the region in contact with the second region B of the side member. With this structure, in the laminate film after welding in contact with the side member, the thickness difference caused by the difference in the position can be reduced.

[0034] Conventionally, a laminated battery is used which includes an electrode body, side members such as terminals, and a laminate film covering a portion of the side members and the electrode body. In addition, in such a laminated battery, due to the arrangement of the batteries in the battery module, the side members may be arranged in the longitudinal direction of the side (in the longitudinal direction of the side). Figure 1 as well as Figure 2 The X direction is configured at a position offset to one side (the first side) relative to the center of the side surface.

[0035] Here, in the manufacture of a laminated battery, when a part of the side member and the electrode body are sealed with a laminate film, a process of welding the laminate film in a manner covering a part of the side member and the electrode body is performed. For example, at a portion where the laminate film and the side member are in contact, a heated welding member is pressed against the side member through the laminate film to melt the inner side (the side in contact with the side member) of the laminate film, so that the laminate film is welded to the side member.

[0036] However, when the laminated film is welded to the electrode body in which the side member is arranged with the side biased toward the first side, the thickness of the laminated film in the area in contact with the side member may vary depending on the location. Specifically, in the laminated film in the area in contact with the side member, the thickness of the laminated film becomes thinner in the first area A, while the thickness of the laminated film becomes thicker in the second area B. That is, in the laminated film in the area in contact with the side member, the thickness of the laminated film on the narrow area side (on the second area B) is thicker. Figure 1 as well as Figure 2 The thickness of the laminated film is thinner on the wide area side (in the region 42A side). Figure 1 as well as Figure 2 (the area on the side of area 41A in the figure), the thickness of the laminate film becomes thicker.

[0037] The reason is presumably as follows.

[0038] When the laminate film is welded to the side member, the heat applied to the laminate film is also absorbed by the side member and the electrode body, so all the applied heat does not contribute to the melting of the inner surface of the laminate film. In addition, in an electrode body in which the side member is arranged on one side of the side of the electrode body, it can be considered that the side member is not heated in the long side direction (in the electrode body). Figure 1 as well as Figure 2 In the X direction, there is a difference in the amount of heat absorbed by the electrode body on one side and the other side of the side part. That is, it can be considered that on the side of the electrode body, in the side part (i.e., the second area B) on the side close to the wide area, the amount of heat absorbed by the electrode body during the welding of the laminated film increases, and in the side part (i.e., the first area A) on the side close to the narrow area, the amount of heat absorbed by the electrode body decreases. It is speculated that this is because the volume of the electrode body that contributes to heat absorption on the wide area side (i.e., the volume of the electrode body that exists near the second area B of the side part) is larger than the volume of the electrode body that contributes to heat absorption on the narrow area side (i.e., the volume of the electrode body that exists near the first area A of the side part). Moreover, in the laminated film connected to the second area B of the side part, since the amount of heat absorbed by the electrode body is large, the heat that contributes to the melting of the inner surface of the laminated film becomes smaller, the amount of melting is reduced, and the thickness of the laminated film after welding becomes thicker. On the other hand, in the laminated film connected to the first region A of the side member, since the amount of heat absorbed by the electrode body is small, the heat contributing to the melting of the inner surface of the laminated film becomes larger, the amount of melting increases, and the thickness of the laminated film after welding becomes thinner. Based on the above mechanism, it is speculated that in the laminated film after welding in the region connected to the side member, the thickness varies depending on the location.

[0039] Therefore, in the manufacturing method of the laminated battery of the embodiment of the present disclosure, in the laminate film used in the welding step, the average thickness a of the region in contact with the first region A of the side member is made thicker than the average thickness b of the region in contact with the second region B of the side member. That is, in the region of the laminate film in contact with the side member, the wide region side (in the region where the thickness becomes thicker after welding) corresponding to the side where the thickness becomes thicker after welding is previously thickened. Figure 1 as well as Figure 2 The thickness of the region (i.e., the second region B) is adjusted to be thinner, and the narrow region side (i.e., the side where the thickness becomes thinner after welding) is adjusted in advance. Figure 1 as well as Figure 2 The thickness of the region (i.e., the first region A) in the right side of the image is adjusted to be thicker. In this way, by pre-adjusting the thickness of the region of the laminate film that contacts the side member, the difference in thickness of the laminate film after welding caused by the difference in the amount of heat absorbed by the electrode body can be offset. As a result, the difference in thickness caused by different locations in the laminate film after welding that contacts the side member can be reduced.

[0040] In the method for manufacturing a laminated battery according to the embodiment of the present disclosure, preferably, in the laminate film used in the welding step, the thickness of the region in contact with the side member continuously increases toward the first side in the longitudinal direction of the side surface.

[0041] exist Figure 2 In the laminate film 28 shown, the thickness of the region in contact with the terminal 26 is 1.04mm in the long side direction of the side surface 4A ( Figure 2 In the X direction in FIG. 1 ), the thickness increases continuously from the region 41A side toward the region 42A side (i.e., the side where the terminal 26 is disposed eccentrically). Therefore, in the region of the laminate film 28 in contact with the terminal 26, when there are the portion 28A, the portion 28B, the portion 28C, and the portion 28D in order from the side close to the region 41A side, the thickness increases in the order of the portion 28A, the portion 28B, the portion 28C, and the portion 28D.

[0042] Thus, in the laminate film used in the welding process, the thickness of the area connected to the side member continuously increases toward the first side in the long side direction of the side. Thus, in the laminate film after welding connected to the side member, the thickness difference caused by different positions can be further reduced.

[0043] Here, the structure in which the thickness of the region of the laminate film in contact with the side member is continuously thickened toward the first side in the long side direction of the side. The "thickness" mentioned here refers to the thickness of the four surfaces (in the side member) in contact with the laminate film. Figure 1 The two surfaces (in the four surfaces of the upper surface 26B, the left side surface 26C, the lower surface 26D and the other right side surface 26E of the terminal 26) parallel to the long side direction of the side surface of the electrode body are Figure 1 The thickness of the laminate film in the region in contact with the side member (in which the upper surface 26B and the lower surface 26D of the terminal 26 are two surfaces). Therefore, the two surfaces parallel to the long side direction of the side in the region in contact with the side member (in which the upper surface 26B and the lower surface 26D of the terminal 26 are two surfaces parallel to the long side direction of the side Figure 1 The thickness of the upper surface 26B and the lower surface 26D (in the middle) only needs to be continuously thickened toward the first side (that is, the narrow region side).

[0044] However, in the manufacturing method of the laminated battery of the embodiment of the present disclosure, the laminate film used in the welding process may not be a structure in which the thickness of the region in contact with the side member continuously increases toward the first side in the long side direction of the side. For example, the thickness of the region in contact with the side member of the laminate film may be a structure in which the thickness gradually increases toward the first side in the long side direction of the side (i.e., the thickness gradually increases in a step-like manner).

[0045] (Measurement method)

[0046] Here, a method for measuring the average thickness a of the region in contact with the first region A of the side member in the laminate film and the average thickness b of the region in contact with the second region B of the side member in the laminate film will be described.

[0047] As described above, the average thickness a of the region in the laminate film that is in contact with the first region A of the side member refers to the average thickness of the laminate film in the region in contact with the first region A in two faces parallel to the long side direction of the side of the electrode body among the four faces in contact with the laminate film in the side member. In addition, the average thickness b of the region in contact with the second region B of the side member refers to the average thickness of the laminate film in the region in contact with the second region B in two faces parallel to the long side direction of the side of the electrode body among the four faces in contact with the laminate film in the side member.

[0048] Moreover, for the average thickness a, the thickness of the laminated film in the region connected to the first region A among two faces parallel to the long side direction of the side of the electrode body among the four faces where the laminated film is in contact in the side member is measured at any 10 locations, and the arithmetic mean thereof is taken as the average thickness a. On the other hand, for the average thickness b, the thickness of the laminated film in the region connected to the second region B among two faces parallel to the long side direction of the side of the electrode body among the four faces where the laminated film is in contact in the side member is measured at any 10 locations, and the arithmetic mean thereof is taken as the average thickness b.

[0049] Next, a battery module, a battery pack, and a vehicle including a laminated battery manufactured by a laminated battery manufacturing method according to an embodiment of the present disclosure will be described using the drawings.

[0050] (Overall Structure of Vehicle 100)

[0051] Figure 3 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 3 As shown, the vehicle 100 is an electric vehicle (BEV) having a battery pack 10 mounted under the floor. It should be noted that the arrows UP, FR, and LH in the respective figures 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, respectively. When the front-rear, left-right, up-down directions are used for explanation, unless otherwise specified, they indicate 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.

[0052] As an example, the vehicle 100 of the present embodiment includes a DC / DC converter 102, an electric compressor 104, and a PTC (Positive Temperature Coefficient) 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.

[0053] 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 electric power to motor 108 via inverter 112, the rear wheels rotate and vehicle 100 travels.

[0054] 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 charger 114 .

[0055] It should be noted that the configuration and structure of the various components constituting the vehicle 100 are not limited to the above structure. For example, it can also be applied to a hybrid vehicle (HV: Hybrid Vehicle) or a plug-in hybrid vehicle (PHEV: Plug-in Hybrid Electric Vehicle) equipped with an engine. In addition, in the present embodiment, the motor 108 is mounted on the rear of the vehicle and is a rear-wheel drive vehicle, but it is not limited to this. The motor 108 can also be mounted on the front of the vehicle. A front-wheel drive vehicle can also be mounted on the front and rear of the vehicle. A pair of motors 108 can also be mounted. In addition, it can also be a vehicle with an in-wheel motor on each wheel.

[0056] 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.

[0057] 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 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 aluminum alloy extrusion by laser welding or the like, thereby forming the outer shell of the battery module 11.

[0058] 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. Bus bars (not shown) are welded to both ends of the battery module 11 in the vehicle width direction.

[0059] 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.

[0060] Figure 5 1 is a top view of the battery module 11 with the upper cover removed. The battery module 11 has a battery cell 20 which is a laminated battery. 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 bonded to each other.

[0061] A flexible printed circuit (FPC) 22 is disposed on the battery cell 20. The flexible printed circuit 22 is formed in a strip shape with the vehicle width direction as the long side direction, and thermistors 24 are provided at both ends of the flexible printed circuit 22. The thermistor 24 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.

[0062] In addition, one or more buffer materials (not shown) are accommodated inside the battery module 11. For example, the buffer material 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, the buffer material is arranged at both ends and the center of the long side direction of the battery module 11.

[0063] 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 therein. The electrode body is formed by laminating a positive electrode, a negative electrode, and a separator, and is sealed by a laminate film 28 .

[0064] In this embodiment, as an example, the electrode body receiving portion is formed by folding and laminating a sheet-shaped laminate film 28 that has been embossed. It should be noted that two structures can be used: a single-cup embossed structure in which embossing is performed at one location and a double-cup embossed structure in which embossing is performed at two locations. However, in this embodiment, a single-cup embossed structure with a drawing depth of about 8 mm to 10 mm is used.

[0065] The upper ends of both ends of the battery cell 20 in the longitudinal direction are bent, and the corners are formed into outer shapes. In addition, the upper end of the battery cell 20 is bent, and the fixing band 30 is wound around the upper end of the battery cell 20 along the longitudinal direction.

[0066] Here, terminals (tabs) 26 are provided at both ends in the longitudinal direction of the battery cell 20. 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.

[0067] The length CW1 of the battery cell 20 in the vehicle width direction is, for example, 530 mm to 600 mm, 600 mm to 700 mm, 700 mm to 800 mm, 800 mm to 900 mm, or 1000 mm or more, the length CW2 of the region where the electrode body is housed is, for example, 500 mm to 520 mm, 600 mm to 700 mm, 700 mm to 800 mm, 800 mm to 900 mm, or 1000 mm or more, and the height CH of the battery cell 20 is, for example, 80 mm to 110 mm, 110 mm to 140 mm. In addition, the thickness of the battery cell 20 is 5.0 mm to 7.0 mm, 7.0 mm to 9.0 mm, or 9.0 mm to 11.0 mm, and the height TH of the terminal 26 is 40 mm to 50 mm, 50 mm to 60 mm, or 60 mm to 70 mm.

Claims

1. A method for manufacturing a laminated battery, the laminated battery comprising an electrode body, a side member arranged on a side of the electrode body, and a laminate film covering a portion of the side member and the electrode body, the side member being arranged in a position in a long side direction of the side relative to a center of the side toward a first side in the long side direction, wherein: The method for manufacturing a laminated battery includes a welding step of welding the laminate film so as to cover a part of the side member and the electrode body. In the side member, when the area on the first side is set as a first area and the area on the second side opposite to the first side is set as a second area with the center of the side member in the long side direction of the side as a boundary, An average thickness of a region of the laminate film used in the welding step that is in contact with the first region of the side member is greater than an average thickness of a region of the laminate film that is in contact with the second region of the side member.

2. The method for manufacturing a laminated battery according to claim 1, wherein: The thickness of the laminate film used in the welding step in a region in contact with the side member continuously increases toward the first side in the longitudinal direction of the side surface.

3. The method for manufacturing a laminated battery according to claim 1, wherein: The thickness of the region of the laminate film used in the welding step that is in contact with the side member gradually increases toward the first side in the longitudinal direction of the side surface.

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