Method for manufacturing battery pack, and battery pack

Abstract

To suppress the occurrence of galvanic corrosion caused by moisture adhering to a welded portion where a first metal and a second metal are mixed.SOLUTION: A method for manufacturing a battery pack includes a first preparation step (S11) of preparing a first base material made of a first metal and a first member having a first plating layer made of a specific metal different from the first metal on the surface of the first base material. The method for manufacturing a battery pack includes a second preparation step (S11) of preparing a second base material made of a second metal different from the first metal and the specific metal, and a second member having a second plating layer made of the specific metal on the surface of the second base material. The method for manufacturing a battery pack includes a placement step (S12) of overlapping and arranging the first member and the second member such that the first plating layer and the second plating layer are in contact with each other. The method for manufacturing a battery pack includes a welding step (S13) of welding the first member and the second member by irradiating the overlapping portion of the first member and the second member with laser beam, after the placement step.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a battery pack and a battery pack. [Background technology]

[0002] The battery pack of Patent Document 1 includes multiple cell batteries and multiple bus bars. The cell batteries are generally rectangular parallelepiped in shape. The cell batteries include a positive terminal and a negative terminal. The terminals of each cell battery are connected to a bus bar. Specifically, the bus bar connects the positive terminal of a cell battery to the negative terminal of the cell battery adjacent to that cell battery. The bus bar is made of a metal primarily containing aluminum. The positive terminal is made of a metal primarily containing aluminum. The portion of the negative terminal that contacts the bus bar is made of a metal primarily containing aluminum. Meanwhile, the remaining portion of the negative terminal is made of a metal primarily containing copper. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-088443 Summary of the Invention [Problem to be solved by the invention]

[0004] In a battery pack such as that described in Patent Document 1, moisture may adhere to the boundary between the aluminum-based portion and the copper-based portion of the negative terminal. When moisture adheres to the contact area between the two types of metal, so-called galvanic corrosion may occur. While a negative terminal made of two types of metals is used as an example here, the present invention is not limited to this. For example, if two types of metals are present near the joints between the bus bar and each terminal, the same problem as described above may occur. [Means for solving the problem]

[0005] A method for manufacturing a battery pack to solve the above problem includes a first preparation step of preparing a first base material made of a first metal and a first member having a first plating layer made of a specific metal different from the first metal on a surface of the first base material; a second preparation step of preparing a second base material made of a second metal different from the first metal and the specific metal, and a second member having a second plating layer made of the specific metal on a surface of the second base material; an arrangement step of overlapping and arranging the first member and the second member so that the first plating layer and the second plating layer are in contact; and a welding step of welding the first member and the second member after the arrangement step by irradiating a laser beam onto the overlapping portion of the first member and the second member so that a welded portion where the laser beam is irradiated is formed where the first metal and the second metal are mixed and a tightly adhered portion is formed around the welded portion where the specific metal of the first plating layer and the specific metal of the second plating layer are tightly adhered.

[0006] A battery pack for solving the above problem comprises a first member having a first base material made of a first metal and a first plating layer made of a specific metal different from the first metal on the surface of the first base material; and a second member having a second base material made of a second metal different from the first metal and the specific metal and a second plating layer made of the specific metal on the surface of the second base material, wherein the first member and the second member overlap so that the first plating layer and the second plating layer are in contact, and the first member and the second member are joined by a weld located at the overlapping portion of the first member and the second member, and a contact portion where the specific metal of the first plating layer and the specific metal of the second plating layer are in close contact is located around the weld in the overlapping portion of the first member and the second member. [Effects of the Invention]

[0007] According to the above configuration, it is possible to prevent galvanic corrosion from occurring at the welded portion where the first metal and the second metal are mixed, which would otherwise be caused by moisture adhering to the welded portion. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a schematic configuration of a battery pack according to a first embodiment. [Figure 2] FIG. 2 is a perspective view showing a schematic configuration of the lithium ion secondary battery according to the first embodiment. [Figure 3] FIG. 3 is an explanatory view showing a part of the electrode assembly according to the first embodiment in a developed form. [Figure 4] FIG. 4 is a perspective view showing the peripheral configuration of the bus bar according to the first embodiment. [Figure 5] FIG. 5 is a cross-sectional view showing a connection configuration of the bus bar and the negative electrode terminal according to the first embodiment. [Figure 6] FIG. 6 is a schematic diagram showing the configuration of a manufacturing apparatus according to the first embodiment. [Figure 7] FIG. 7 is a flowchart showing manufacturing control according to the first embodiment. [Figure 8] FIG. 8 is an explanatory view of the welding process according to the first embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing an actual connection configuration of the bus bar and the negative electrode terminal according to the first embodiment. [Figure 10] FIG. 10 is a flowchart showing manufacturing control according to the second embodiment. [Figure 11] FIG. 11 is an explanatory view of the first welding step according to the second embodiment. [Figure 12] FIG. 12 is an explanatory view of the second welding step according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment <Battery pack configuration> A first embodiment of the present invention will be described below with reference to Figures 1 to 9. First, the general configuration of a battery pack 100 will be described.

[0010] As shown in FIG. 1 , the battery pack 100 includes multiple lithium-ion secondary batteries 10, multiple spacers 40, and a housing case 90. The housing case 90 includes two housing spaces 90A. Each housing space 90A is a rectangular prism-shaped space. The housing case 90 houses multiple lithium-ion secondary batteries 10 and multiple spacers 40 in each housing space 90A. Two adjacent lithium-ion secondary batteries 10 are arranged side by side with a spacer 40 sandwiched between them. The spacer 40 has a generally rectangular plate shape. The two adjacent lithium-ion secondary batteries 10 are arranged such that their positive electrode terminals 13A and negative electrode terminals 15 (described later) are alternately rotated. Therefore, the positive electrode terminal 13A of one of the adjacent lithium-ion secondary batteries 10 is adjacent to the negative electrode terminal 15 of the other lithium-ion secondary battery 10. In this embodiment, the lithium-ion secondary batteries 10 are so-called cell batteries. It should be noted that bus bars 50, which will be described later, are not shown in Fig. 1. Furthermore, in cases where there are a plurality of components, only some of the components may be given reference numerals.

[0011] 2, the lithium ion secondary battery 10 includes a case 11, a lid 12, a positive electrode terminal 13A, and a negative electrode terminal 15. The lithium ion secondary battery 10 also includes a positive electrode current collector 14A, a negative electrode current collector 14B, an electrode assembly 20, and a nonaqueous electrolyte 31.

[0012] The case 11 has a rectangular box shape with an opening. The opening of the case 11 has a rectangular shape. One example of the material of the case 11 is an alloy containing aluminum as a main component, i.e., an aluminum alloy. Here, the main component refers to the component with the largest elemental proportion in the material. The lid 12 has a rectangular plate shape. One example of the material of the lid 12 is an aluminum alloy. The lid 12 closes the opening of the case 11. As a result, the case 11 and the lid 12 form a sealed battery case. The electrode assembly 20 is located within the battery case. That is, the case 11 accommodates the electrode assembly 20 within the case 11. Details of the electrode assembly 20 will be described later. Furthermore, a nonaqueous electrolyte 31 is stored within the battery case. That is, the case 11 stores the nonaqueous electrolyte 31 within the case 11.

[0013] The positive electrode terminal 13A has a generally rectangular plate shape. The positive electrode terminal 13A is attached to the lid 12 via an insulating plate member (not shown). The main surface of the positive electrode terminal 13A is approximately parallel to the main surface of the lid 12. Here, the main surface of a plate-shaped member refers to the largest flat surface among the outer surfaces of the member in question. The positive electrode terminal 13A is positioned to one side of the center in the longitudinal direction of the lid 12. The positive electrode terminal 13A is connected to the electrode body 20 via a positive electrode current collector 14A. The positive electrode terminal 13A is made of, for example, an aluminum alloy. The positive electrode current collector 14A is made of, for example, an aluminum alloy. In this embodiment, the aluminum alloy is an example of a metal containing aluminum as its main component.

[0014] The negative electrode terminal 15 has a generally rectangular plate shape. The negative electrode terminal 15 is attached to the lid 12 via an insulating plate member (not shown). The main surface of the negative electrode terminal 15 is approximately parallel to the main surface of the lid 12. The negative electrode terminal 15 is located on the opposite side of the longitudinal center of the lid 12 from the positive electrode terminal 13A. The negative electrode terminal 15 is connected to the electrode body 20 via the negative electrode current collector 14B. The material of most of the negative electrode terminal 15 is, for example, an alloy containing copper as a main component, i.e., a copper alloy. The specific composition of the material of the negative electrode terminal 15 will be described later. The material of the negative electrode current collector 14B is, for example, a copper alloy. In this embodiment, the copper alloy is an example of a metal containing copper as a main component.

[0015] As shown in FIG. 3, the electrode assembly 20 includes a positive electrode sheet 21, a negative electrode sheet 24, and two separators 27. The electrode assembly 20 is a wound assembly formed by winding a laminate in which the positive electrode sheet 21, the negative electrode sheet 24, and the two separators 27 are stacked. The positive electrode sheet 21, the negative electrode sheet 24, and the separator 27 each have a rectangular foil shape. In the state of the laminate before being wound, the positive electrode sheet 21, the negative electrode sheet 24, and the separator 27 are stacked so that their long sides extend in the same direction. Hereinafter, the direction in which the long sides extend is referred to as the long side direction D1. In the state of the laminate before being wound, the positive electrode sheet 21, the separator 27, the negative electrode sheet 24, and the separator 27 are stacked in this order.

[0016] The positive electrode sheet 21 includes a positive electrode current collector 22 and two positive electrode composite layers 23. The positive electrode current collector 22 is shaped like a rectangular foil. One example of the material of the positive electrode current collector 22 is an aluminum alloy. The positive electrode current collector 22 functions as a current collector for the positive electrode.

[0017] One of the two positive electrode composite layers 23 is attached to a first surface of the positive electrode current collector 22. The other of the two positive electrode composite layers 23 is attached to a second surface of the positive electrode current collector 22 opposite the first surface. Each positive electrode composite layer 23 is attached to the entire positive electrode current collector 22 except for a portion including a first end in a short side direction D2 perpendicular to the long side direction D1. As a result, the positive electrode current collector 22 has a positive electrode uncoated portion 22A in which the positive electrode composite layer 23 is not attached and the positive electrode current collector 22 is exposed in a portion including the first end in the short side direction D2. In the wound state, the positive electrode uncoated portion 22A is pressed against the positive electrode current collector 20A to form the positive electrode current collector 20A. As shown in FIG. 2, the positive electrode current collector 20A is connected to a positive electrode terminal 13A via a positive electrode current collector member 14A.

[0018] 3, the positive electrode mixture layer 23 is formed by hardening a positive electrode mixture paste. The positive electrode mixture paste includes a positive electrode active material, a positive electrode solvent, a positive electrode conductive material, and a positive electrode binder. The positive electrode mixture layer 23 is formed by drying the positive electrode mixture paste and evaporating the positive electrode solvent. Therefore, the positive electrode mixture layer 23 includes a positive electrode active material, a positive electrode conductive material, and a positive electrode binder.

[0019] The positive electrode active material is a lithium-containing composite oxide capable of absorbing and releasing lithium ions, which are charge carriers in the lithium-ion secondary battery 10. The lithium-containing composite oxide is an oxide containing lithium and a metal element other than lithium. The metal element other than lithium is, for example, one or more selected from the group consisting of nickel, cobalt, manganese, vanadium, magnesium, molybdenum, niobium, titanium, tungsten, aluminum, and iron contained in the lithium-containing composite oxide as iron phosphate.

[0020] For example, the lithium-containing composite oxide is lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or lithium manganese oxide (LiMn2O4). Also, for example, the lithium-containing composite oxide is a ternary lithium-containing composite oxide containing nickel, cobalt, and manganese, such as lithium nickel cobalt manganese oxide (LiNiCoMnO2). Furthermore, for example, the lithium-containing composite oxide is lithium iron phosphate (LiFePO4).

[0021] The positive electrode solvent is an NMP (N-methyl-2-pyrrolidone) solution, which is an example of an organic solvent. The positive electrode conductive material may be, for example, carbon black such as acetylene black or ketjen black, carbon fiber such as carbon nanotube or carbon nanofiber, or graphite. The positive electrode binder is an example of a resin component contained in the positive electrode mixture paste. Examples of the positive electrode binder include polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), and styrene butadiene rubber (SBR).

[0022] 3, the negative electrode sheet 24 includes a negative electrode current collector 25 and two negative electrode composite layers 26. The negative electrode current collector 25 has a rectangular foil shape. One example of the material of the negative electrode current collector 25 is a copper alloy. The negative electrode current collector 25 functions as a current collector for the negative electrode.

[0023] One of the two negative electrode composite layers 26 is attached to a first surface of the negative electrode current collector 25. The other of the two negative electrode composite layers 26 is attached to a second surface of the negative electrode current collector 25 opposite the first surface. Each negative electrode composite layer 26 is attached to the entire negative electrode current collector 25 except for a portion including the second end in the short side direction D2. As a result, the negative electrode current collector 25 has a negative electrode uncoated portion 25A where the negative electrode composite layer 26 is not attached and the negative electrode current collector 25 is exposed in a portion including the second end in the short side direction D2. Then, in the wound state, the negative electrode uncoated portion 25A is pressed against the negative electrode current collector 20B to form the negative electrode current collector 20B. As shown in FIG. 2, the negative electrode current collector 20B is connected to the negative electrode terminal 15 via a negative electrode current collector member 14B.

[0024] As shown in FIG. 3, the negative electrode mixture layer 26 is formed by hardening a negative electrode mixture paste. The negative electrode mixture paste includes a negative electrode active material, a negative electrode solvent, a negative electrode thickener, and a negative electrode binder. The negative electrode mixture layer 26 is formed when the negative electrode mixture paste dries and the negative electrode solvent evaporates. Therefore, the negative electrode mixture layer 26 includes a negative electrode active material, a negative electrode thickener, and a negative electrode binder. The negative electrode mixture layer 26 may further include an additive such as a conductive material.

[0025] The negative electrode active material is a material capable of absorbing and releasing lithium ions. Examples of the negative electrode active material include carbon materials such as graphite, non-graphitizable carbon, graphitizable carbon, and carbon nanotubes. One example of the negative electrode solvent is water. One example of the negative electrode thickener is CMC (carboxymethyl cellulose), which contains a sodium salt. One example of the negative electrode binder is the same as the positive electrode binder. One example of the negative electrode binder is SBR (styrene butadiene copolymer), which contains a sodium salt.

[0026] The separator 27 prevents contact between the positive electrode sheet 21 and the negative electrode sheet 24. The separator 27 also holds the nonaqueous electrolyte solution 31 between the positive electrode sheet 21 and the negative electrode sheet 24. When the electrode assembly 20 is immersed in the nonaqueous electrolyte solution 31, the nonaqueous electrolyte solution 31 permeates from the ends of the separator 27 toward the center.

[0027] The separator 27 is a nonwoven fabric made of polypropylene, etc. Examples of the separator 27 that can be used include porous polymer membranes such as porous polyethylene membranes, porous polyolefin membranes, and porous polyvinyl chloride membranes, and ion-conductive polymer electrolyte membranes.

[0028] The nonaqueous electrolyte 31 is a composition in which a supporting salt is contained in a nonaqueous solvent. The nonaqueous solvent may be one or more materials selected from the group consisting of propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, etc. The supporting salt may be one or more lithium compounds (lithium salts) selected from LiPF, LiBF, LiClO, LiAsF, LiCF, SO, LiCF, SO, LiN(CF, SO), LiC(CF, SO), LiI, etc. In this embodiment, ethylene carbonate is used as the nonaqueous solvent.

[0029] The non-aqueous electrolyte 31 contains, as an additive, lithium salt LiBOB (lithium bis(oxalato)borate). The concentration of LiBOB in the non-aqueous electrolyte 31 is, for example, 0.001 to 0.1 mol / L. The non-aqueous electrolyte 31 also contains, as an additive, an isocyanate compound having an isocyanate group. The concentration of the isocyanate compound in the non-aqueous electrolyte 31 is, for example, approximately 0.1 to 2.0 mass%.

[0030] <Busbar peripheral configuration> As shown in FIG. 4 , the battery pack 100 includes a plurality of bus bars 50. The bus bars 50 are shaped like rectangular plates having long and short sides. A portion of the main surface of each bus bar 50, including a first end, contacts the main surface of the positive terminal 13A of each lithium-ion secondary battery 10. The bus bars 50 are joined to the positive terminal 13A by laser welding. A portion of each bus bar 50, including a second end, contacts the main surface of the negative terminal 15 of the lithium-ion secondary battery 10 adjacent to the lithium-ion secondary battery 10 to which the first end of the bus bar 50 is joined. The bus bars 50 are joined to the negative terminal 15 by laser welding. That is, the bus bars 50 connect the positive terminal 13A of one of the two adjacent lithium-ion secondary batteries 10 to the negative terminal 15 of the other lithium-ion secondary battery 10.

[0031] Next, a specific connection configuration of the bus bar 50 and the negative electrode terminal 15 will be described with reference to Fig. 5. In the following, among the directions in which the bus bar 50 and the negative electrode terminal 15 overlap, the direction in which the bus bar 50 is positioned relative to the negative electrode terminal 15 is referred to as an upward direction DP, and the opposite direction is referred to as a downward direction DN.

[0032] As shown in FIG. 5 , the negative electrode terminal 15 includes a terminal substrate 16 and a terminal plating layer 17. The terminal substrate 16 has a generally rectangular plate shape. The thickness of the terminal substrate 16 is, for example, approximately 0.1 mm to 2 mm. The terminal substrate 16 is made of a copper alloy. The terminal plating layer 17 covers the entire surface of the terminal substrate 16. The thickness of the terminal plating layer 17 is approximately several μm to several tens of μm. Note that the thickness of the terminal plating layer 17 is exaggerated in FIG. 5 and other figures. The material of the terminal plating layer 17 is a metal containing nickel as a main component. That is, the material of the terminal plating layer 17 is different from the material of the terminal substrate 16. In this embodiment, the negative electrode terminal 15 is an example of a second member. The terminal substrate 16 is an example of a second substrate. The terminal plating layer 17 is an example of a second plating layer. The copper alloy used as the material of the terminal substrate 16 is an example of a second metal.

[0033] The busbar 50 includes a busbar substrate 51 and a busbar plating layer 52. The busbar substrate 51 is shaped like a rectangular plate having long and short sides. The thickness of the busbar substrate 51 is, for example, approximately 0.1 mm or more and 2 mm or less. The busbar substrate 51 is made of an aluminum alloy. That is, the material of the busbar substrate 51 is different from the material of the terminal substrate 16. The busbar plating layer 52 covers the main surface of the busbar substrate 51 on the downward DN side. Therefore, the busbar 50 and the negative terminal 15 overlap such that the busbar plating layer 52 and the terminal plating layer 17 are in contact with each other. The thickness of the busbar plating layer 52 is approximately several μm to several tens of μm. Note that the thickness of the busbar plating layer 52 is exaggerated in FIG. 5 and other figures. The material of the busbar plating layer 52 is a metal containing nickel as a main component. That is, the material of the busbar plating layer 52 is the same as the material of the terminal plating layer 17. Furthermore, the materials of the busbar plating layer 52 and the terminal plating layer 17 are different from the materials of the busbar substrate 51 and the terminal substrate 16. In this embodiment, the busbar 50 is an example of a first member. The busbar substrate 51 is an example of a first substrate. The busbar plating layer 52 is an example of a first plating layer. The aluminum alloy used as the material of the busbar substrate 51 is an example of a first metal. The metal containing nickel as a main component used as the material of the terminal plating layer 17 and the busbar plating layer 52 is an example of a specific metal.

[0034] As described above, the busbar 50 and the negative electrode terminal 15 are joined by laser welding. Specifically, the busbar 50 and the negative electrode terminal 15 are joined by a weld WA located at the overlapping portion of the busbar 50 and the negative electrode terminal 15. In this embodiment, when the weld WA is viewed from the upward direction DP toward the downward direction DN, the shape of the weld WA is generally linear. Note that the weld WA is a portion where the aluminum alloy, which is the material of the busbar substrate 51, and the copper alloy, which is the material of the terminal substrate 16, are mixed together during the process of welding the busbar 50 and the negative electrode terminal 15. Furthermore, the weld WA may be a mixture of the nickel-based metal, which is the material of the busbar plating layer 52, and the nickel-based metal, which is the material of the terminal plating layer 17. Furthermore, in the overlapping portion of the busbar 50 and the negative terminal 15, a contact portion WB is located around the welded portion WA, where the nickel-based metal of the busbar plating layer 52 and the nickel-based metal of the terminal plating layer 17 are in close contact with each other. More specifically, the contact portion WB surrounds the welded portion WA from the outside.

[0035] <Outline of manufacturing equipment> Next, a schematic configuration of the manufacturing apparatus 200 will be described with reference to Fig. 6. The manufacturing apparatus 200 is an apparatus for manufacturing the battery pack 100.

[0036] As shown in Fig. 6, the manufacturing apparatus 200 includes a manufacturing facility 210, an input device 220, a display 230, and a manufacturing management device 290. The manufacturing facility 210 includes various types of equipment for manufacturing the battery pack 100. Here, the various types of equipment are equipment used in manufacturing control, which will be described later. That is, the various types of equipment include a conveying device for conveying articles, an alignment device for arranging and aligning articles, a laser welding device, and the like. The input device 220 includes, for example, a keyboard and a pointing device. The display 230 is capable of displaying various types of information.

[0037] The manufacturing management device 290 includes an execution device 291 and a storage device 292. An example of the execution device 291 is a CPU. The storage device 292 includes a read-only ROM, a readable / writable volatile RAM, and a readable / writable non-volatile storage. The storage device 292 stores various programs and various data in advance. Specifically, the storage device 292 stores a manufacturing program 292A in advance as one of the various programs. The execution device 291 executes the manufacturing program 292A stored in the storage device 292 to perform various processes described below. In other words, the manufacturing management device 290 executes various steps related to the manufacturing method of the battery pack 100.

[0038] The execution device 291 of the manufacturing management apparatus 290 acquires various pieces of information from the input device 220. The execution device 291 also displays various pieces of information on the display 230 by outputting a control signal to the display 230. Furthermore, the execution device 291 outputs a control signal to the manufacturing equipment 210, thereby manufacturing the battery pack 100 using the manufacturing equipment 210.

[0039] <Manufacturing Control> Next, the manufacturing control executed by the manufacturing management device 290 will be described with reference to Fig. 7. This manufacturing control is control for manufacturing the battery pack 100. Note that the following description will be given assuming control for manufacturing one battery pack 100. In this embodiment, the execution device 291 of the manufacturing management device 290 starts the manufacturing control when an operator requests the execution of the manufacturing control via the input device 220, for example.

[0040] As shown in FIG. 7 , when the execution device 291 of the manufacturing management apparatus 290 starts manufacturing control, it executes the process of step S11. In step S11, the execution device 291 executes a preparation process of preparing various components for manufacturing the battery pack 100. Specifically, the execution device 291 uses a conveyance device included in the manufacturing equipment 210 to convey a plurality of lithium-ion secondary batteries 10, a plurality of spacers 40, a plurality of bus bars 50, and a housing case 90 to a predetermined location in order to use the various components in step S12, which will be described later. In this embodiment, the preparation process of step S11 includes a first preparation process of preparing the bus bar 50, which is a first component. The preparation process of step S11 also includes a second preparation process of preparing the negative electrode terminal 15, which is a second component. After step S11, the execution device 291 advances the process to step S12.

[0041] In step S12, the execution device 291 executes an arrangement step of arranging various components. Specifically, the execution device 291 arranges the various components as follows. First, as shown in FIG. 1, the execution device 291 arranges a plurality of lithium-ion secondary batteries 10 and a plurality of spacers 40 in the housing space 90A of the housing case 90 using an alignment device included in the manufacturing equipment 210. At this time, the execution device 291 arranges the lithium-ion secondary batteries 10 and the spacers 40 alternately. Furthermore, the execution device 291 arranges the adjacent plurality of lithium-ion secondary batteries 10 so that the positive electrode terminals 13A and the negative electrode terminals 15 are alternately inverted. Next, as shown in FIG. 4, the execution device 291 arranges the bus bars 50 by using the manufacturing equipment 210 so that they overlap the positive electrode terminals 13A and the negative electrode terminals 15 of two adjacent lithium-ion secondary batteries 10. At this time, the executing unit 291 overlaps the busbar 50 with the surfaces of the positive terminal 13A and the negative terminal 15 in the upward direction DP, with the busbar plating layer 52 of the busbar 50 positioned in the downward direction DN. In other words, the executing unit 291 overlaps and arranges the busbar 50 and the negative terminal 15 so that the busbar plating layer 52 and the terminal plating layer 17 are in contact with each other. As shown in FIG. 7 , after step S12, the executing unit 291 advances the process to step S13.

[0042] In step S13, the executing unit 291 executes a welding process to weld the busbar 50 and the negative terminal 15 together. Specifically, as shown in FIG. 8 , the executing unit 291 uses a laser welding device included in the manufacturing equipment 210 to irradiate the overlapping portion of the busbar 50 and the negative terminal 15 with a laser beam from an upward direction DP to a downward direction DN, thereby welding the busbar 50 and the negative terminal 15 together. At this time, the executing unit 291 irradiates the overlapping portion of the busbar 50 and the negative terminal 15 with a laser beam having a predetermined intensity ZR and a predetermined irradiation diameter LD. Then, the executing unit 291 moves the laser beam relative to the busbar 50 and the negative terminal 15. Note that the shape of the movement trajectory of the laser beam is linear. In this manner, the executing unit 291 irradiates the overlapping portion of the busbar 50 and the negative terminal 15 with the laser beam having the predetermined intensity ZR within a predetermined range AR. Here, the specified strength ZR is predetermined as a strength sufficient to allow the thermal energy of the laser beam to reach the terminal substrate 16 of the negative terminal 15, taking into account, for example, the irradiation time of the laser beam on the overlapping portion of the busbar 50 and the negative terminal 15. The specified range AR is a range that is generally linear when the overlapping portion of the busbar 50 and the negative terminal 15 is viewed from the upward direction DP toward the downward direction DN. In FIG. 8 , the laser beam is indicated by a thick arrow. As a result, as shown in FIG. 5 , in the overlapping portion of the busbar 50 and the negative terminal 15, a weld WA is formed in the area irradiated with the laser beam, where the aluminum alloy, which is the material of the busbar substrate 51, and the copper alloy, which is the material of the terminal substrate 16, are mixed. As described above, when the weld WA is viewed from the upward direction DP toward the downward direction DN, the shape of the weld WA is generally linear. Additionally, in the portion where the busbar 50 and the negative electrode terminal 15 overlap, an adhesion portion WB is formed around the welded portion WA, where the metal mainly composed of nickel, which is the material of the busbar plating layer 52, and the metal mainly composed of nickel, which is the material of the terminal plating layer 17, are in close contact with each other. As shown in FIG. 7, after step S13, the executing unit 291 ends the current manufacturing control.

[0043] <Operation of this embodiment> As shown in FIG. 5 , even if the busbar 50 and the negative terminal 15 are in contact with each other at the overlapping portion of the busbar 50 and the negative terminal 15, a gap may be formed between the busbar 50 and the negative terminal 15 due to, for example, slight irregularities on the busbar 50 and the negative terminal 15. The welded portion WA is a portion where the aluminum alloy, which is the material of the busbar substrate 51, and the copper alloy, which is the material of the terminal substrate 16, are mixed together during the process of welding the busbar 50 and the negative terminal 15. Therefore, if the contact portion WB were not present, moisture that penetrates through the gap between the busbar 50 and the negative terminal 15 would adhere to the welded portion WA. The moisture adhering to the welded portion WA may cause galvanic corrosion at the welded portion WA.

[0044] In this regard, as shown in FIG. 8 , in the welding process of step S13, in this embodiment, the temperatures of the busbar 50 and the negative terminal 15 increase around the area irradiated with the laser light. When the busbar plating layer 52 and the terminal plating layer 17 are broken due to the increase in temperature of the busbar 50 and the negative terminal 15, a welded portion WA is formed in which the aluminum alloy, which is the material of the busbar substrate 51, and the copper alloy, which is the material of the terminal substrate 16, are mixed together. At this time, the nickel-based metal, which is the material of the busbar plating layer 52 and the terminal plating layer 17, also melts around the welded portion WA. Therefore, as shown in FIGS. 5 and 9 , a contact portion WB is formed in which the nickel-based metal, which is the material of the busbar plating layer 52 and the terminal plating layer 17, are in close contact with each other. That is, even when a welded portion WA is formed in which the aluminum alloy, which is the material of the busbar substrate 51, and the copper alloy, which is the material of the terminal substrate 16, are mixed together, a contact portion WB is formed around the welded portion WA.

[0045] <Effects of this embodiment> (1-1) According to this embodiment, as shown in Figures 5 and 9, the contact zone WB is located around the weld zone WA. Therefore, even if moisture attempts to penetrate into the weld zone WA through a gap between the bus bar 50 and the negative electrode terminal 15, the presence of the contact zone WB prevents the moisture from penetrating into the weld zone WA. As a result, it is possible to prevent galvanic corrosion at the weld zone WA from occurring due to moisture adhering to the weld zone WA.

[0046] (1-2) In the battery pack 100, the first metal, i.e., the material of the busbar substrate 51, is a metal primarily composed of aluminum. The second metal, i.e., the material of the terminal substrate 16, is a metal primarily composed of copper. The specific metal, i.e., the material of the terminal plating layer 17 and the busbar plating layer 52, is a metal primarily composed of nickel. In this battery pack 100, a weld WA is formed in which aluminum, which is the material of the busbar substrate 51, and copper, which is the material of the terminal substrate 16, are mixed. Here, because the difference in ionization tendency between aluminum and copper is relatively large, galvanic corrosion is particularly likely to occur at the weld WA. For this reason, it is particularly preferable to apply the present technology to the battery pack 100.

[0047] Second Embodiment A second embodiment of the present invention will be described below with reference to Figures 10 to 12. In the second embodiment, some steps of manufacturing control are different from those in the first embodiment. In the description of the second embodiment, differences from the first embodiment will be mainly described, and the same components as those in the first embodiment will be denoted by the same reference numerals, and description thereof will be omitted or simplified.

[0048] <Manufacturing Control> As shown in FIG. 10, after step S12, the execution device 291 of the manufacturing management device 290 advances the process to step S13A.

[0049] In step S13A, the executing unit 291 executes a first welding process. Specifically, as shown in FIG. 11 , the executing unit 291 uses a laser welding device included in the manufacturing equipment 210 to irradiate the overlapping portion of the busbar 50 and the negative terminal 15 with laser light from an upward direction DP to a downward direction DN, thereby forming a contact portion WB. At this time, the executing unit 291 irradiates the overlapping portion of the busbar 50 and the negative terminal 15 with laser light having a predetermined first specified intensity ZR1 and a predetermined first specified irradiation diameter LD1. Then, the executing unit 291 moves the laser light relative to the busbar 50 and the negative terminal 15. Note that the shape of the movement trajectory of the laser light is linear. In this manner, the executing unit 291 irradiates the overlapping portion of the busbar 50 and the negative terminal 15 with laser light having the predetermined first specified intensity ZR1 in a predetermined first specified range AR1. Here, the first specified strength ZR1 is predetermined as a strength sufficient to allow the thermal energy of the laser beam to reach the terminal plating layer 17 of the negative terminal 15, taking into account, for example, the irradiation time of the laser beam on the overlapping portion of the busbar 50 and the negative terminal 15. The first specified range AR1 is a range that is generally linear when the overlapping portion of the busbar 50 and the negative terminal 15 is viewed from the upward direction DP toward the downward direction DN. In FIG. 11, the laser beam is indicated by a thick arrow. As a result, as shown in FIG. 12, in the overlapping portion of the busbar 50 and the negative terminal 15, a contact zone WB is formed where the nickel-based metal of the busbar plating layer 52 and the terminal plating layer 17 is in close contact with the laser beam at the location irradiated with the laser beam. When the welded portion WA is viewed from the upward direction DP toward the downward direction DN, the shape of the contact zone WB is generally linear. As shown in FIG. 10, after step S13A, the executing unit 291 proceeds to step S13B.

[0050] In step S13B, the executing unit 291 executes the second welding process. Specifically, as shown in FIG. 12 , the executing unit 291 uses a laser welding device included in the manufacturing equipment 210 to irradiate the portion where the bus bar 50 and the negative electrode terminal 15 overlap with laser light from an upward direction DP to a downward direction DN, thereby forming a welded portion WA. At this time, the executing unit 291 irradiates the portion where the bus bar 50 and the negative electrode terminal 15 overlap with laser light having a predetermined second specified intensity ZR2 and a predetermined second specified irradiation diameter LD2 that is smaller than the first specified irradiation diameter LD1. Then, the executing unit 291 moves the laser light relative to the bus bar 50 and the negative electrode terminal 15. Note that the movement trajectory of the laser light in step S13B is the same as the movement trajectory of the laser light in step S13A. In this manner, the execution device 291 irradiates a laser beam having a predetermined second specified intensity ZR2 onto a predetermined second specified range AR2 within the overlapping portion of the busbar 50 and the negative terminal 15. Here, the second specified intensity ZR2 is predetermined as an intensity sufficient to allow the thermal energy of the laser beam to reach the terminal substrate 16 of the negative terminal 15, taking into account, for example, the irradiation time of the laser beam onto the overlapping portion of the busbar 50 and the negative terminal 15. In other words, the second specified intensity ZR2 is predetermined as an intensity stronger than the first specified intensity ZR1. Furthermore, the second specified range AR2 is a generally linear range when the overlapping portion of the busbar 50 and the negative terminal 15 is viewed from the upward direction DP toward the downward direction DN. Here, as described above, the second specified irradiation diameter LD2 is smaller than the first specified irradiation diameter LD1. Therefore, the second specified range AR2 is predetermined as a range narrower than the first specified range AR1 and within the first specified range AR1. In Fig. 12, the laser light is indicated by a thick arrow. As a result, as shown in Fig. 5, in the overlapping portion of the bus bar 50 and the negative electrode terminal 15, a welded portion WA is formed at the location irradiated with the laser light, where the aluminum alloy, which is the material of the bus bar base material 51, and the copper alloy, which is the material of the terminal base material 16, are mixed together. When the welded portion WA is viewed from the upward direction DP toward the downward direction DN, the shape of the welded portion WA is generally linear.As shown in FIG. 10, after step S13B, the execution unit 291 ends the current manufacturing control.

[0051] <Effects of this embodiment> In this embodiment, in addition to the above-mentioned effects (1-1) and (1-2), the following effect (2-1) is achieved.

[0052] (2-1) As shown in Fig. 10, in the first welding process of step S13A, a laser beam is irradiated onto a first specified area AR1, forming a contact zone WB in the first specified area AR1. Then, in the subsequent second welding process of step S13B, a laser beam is irradiated onto a second specified area AR2, which is an area within the first specified area AR1, forming a weld zone WA in the second specified area AR2. By forming the contact zone WB and the weld zone WA in stages in this manner, the contact zone WB can be more reliably formed around the weld zone WA.

[0053] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0054] The manufacturing control in the first embodiment may be modified. For example, in step S13, the method of irradiating the laser beam may be changed. As a specific example, the execution unit 291 may move the laser beam in an arc relative to the bus bar 50 and the negative electrode terminal 15. In other words, the shape of the movement trajectory of the laser beam may be arc-shaped. In this case, when the welded portion WA is viewed from the upward direction DP toward the downward direction DN, the shape of the welded portion WA is generally arc-shaped. As a specific example, the execution unit 291 may irradiate the laser beam only at one point without moving the laser beam relative to the bus bar 50 and the negative electrode terminal 15. In other words, the execution unit 291 may form the welded portion WA by so-called spot welding. As a specific example, the execution unit 291 may change the direction of irradiating the laser beam depending on the positions and shapes of the bus bar 50 and the negative electrode terminal 15. In other words, the executing device 291 may irradiate the laser light from the side where the negative terminal 15 is located, instead of irradiating the laser light from the side where the bus bar 50 is located, between the bus bar 50 and the negative terminal 15. Note that the above-mentioned change may also be applied to the manufacturing control in the second embodiment.

[0055] For example, the entity that executes the manufacturing control may be changed. As a specific example, instead of the manufacturing management device 290, an operator may execute some or all of the various manufacturing control processes. Note that the above-described changes may also be applied to the manufacturing control in the second embodiment.

[0056] The configuration of the battery pack 100 in the first and second embodiments may be modified. For example, the types of the first metal, the second metal, and the specific metal may be changed. As a specific example, the material of the busbar substrate 51 is not limited to aluminum alloy and may be changed. Also, as a specific example, the material of the terminal substrate 16 is not limited to copper alloy and may be changed. Furthermore, as a specific example, the materials of the terminal plating layer 17 and the busbar plating layer 52 are not limited to metals containing nickel as a main component and may be changed. Note that when changing as described above, it is only necessary that the first metal, the second metal, and the specific metal are of different types.

[0057] For example, the position of the terminal plating layer 17 in the negative electrode terminal 15 may be changed. As a specific example, the terminal plating layer 17 may cover only the principal surface in the upward direction DP of the surface of the terminal substrate 16. In other words, the terminal plating layer 17, which is the second plating layer, may be located at least in a portion that contacts the busbar plating layer 52, which is the first plating layer.

[0058] For example, the position of the busbar plating layer 52 on the busbar 50 may be changed. As a specific example, the busbar plating layer 52 may cover the entire surface of the busbar base material 51. In other words, the busbar plating layer 52, which is the first plating layer, may be located at least in a portion that contacts the terminal plating layer 17, which is the second plating layer.

[0059] For example, the target of application of the present technology may be changed within the battery pack 100. As a specific example, the negative electrode terminal 15 may be made of a first member and a second member. In this case, the present technology may be applied to the negative electrode terminal 15 made of the first member and the second member. Also, as a specific example, the bus bar 50 may be made of a first member and a second member. In this case, the present technology may be applied to the bus bar 50 made of the first member and the second member. [Explanation of symbols]

[0060] WA...weld WB: Close contact area 10...Lithium-ion secondary battery 11...Case 12...lid body 13A...Positive terminal 14A...Positive electrode current collecting member 14B...Negative electrode current collecting member 15...Negative terminal 16...Terminal base material 17...Terminal plating layer 20...Electrode body 40...Spacer 50...busbar 51... Busbar base material 52... Busbar plating layer 90...Storage case 90A...Storage space 100...Battery pack 200…Manufacturing equipment 210...Manufacturing equipment 220...Input device 230...Display 290...Manufacturing control equipment 291...Execution device 292...Storage device 292A...Manufacturing Program

Claims

1. a first preparation step of preparing a first member having a first base material made of a first metal and a first plating layer made of a specific metal different from the first metal on a surface of the first base material; a second preparation step of preparing a second base material made of a second metal different from the first metal and the specific metal, and a second member having a second plating layer made of the specific metal on a surface of the second base material; a positioning step of placing the first member and the second member so that the first plating layer and the second plating layer are in contact with each other; a welding step of welding the first member and the second member by irradiating a laser beam onto an overlapping portion of the first member and the second member after the arranging step, so that a welded portion where the first metal and the second metal are mixed is formed at the irradiated portion with the laser beam, and a tightly adhered portion where the specific metal of the first plating layer and the specific metal of the second plating layer are tightly adhered to each other is formed around the welded portion; Equipped with Battery pack manufacturing method.

2. The welding step includes: a first welding step, which is performed after the placing step, of irradiating a laser beam having a predetermined first specified intensity onto a predetermined first specified range in an overlapping portion between the first member and the second member to form the contact portion; a second welding step, performed after the first welding step, of irradiating a laser beam having a second specified intensity, which is predetermined as an intensity stronger than the first specified intensity, onto a second specified range, which is a range narrower than the first specified range and is predetermined as a range inside the first specified range, in a portion where the first member and the second member overlap, to form the weld; Equipped with The method for manufacturing the battery pack according to claim 1 .

3. the first metal is a metal containing aluminum as a main component, the second metal is a metal containing copper as a main component, The specific metal is a metal containing nickel as a main component. The method for manufacturing the battery pack according to claim 1 or 2.

4. a first member having a first base material made of a first metal and a first plating layer made of a specific metal different from the first metal on a surface of the first base material; a second base material made of a second metal different from the first metal and the specific metal, and a second member having a second plating layer made of the specific metal on a surface of the second base material; the first member and the second member overlap each other so that the first plating layer and the second plating layer are in contact with each other; the first member and the second member are joined by a weld located at an overlapping portion of the first member and the second member, In the overlapping portion between the first member and the second member, a contact portion where the specific metal of the first plating layer and the specific metal of the second plating layer are in close contact with each other is located around the welded portion. Battery pack.

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