Bus bar, battery pack, and manufacturing method of bus bar

Abstract

To simplify a manufacturing process of a bus bar in the bus bar composed of a plurality of metals.SOLUTION: A bus bar 50 includes a coupling part 80, a first connection part 60, and a second connection part 70. The first connection part 60 includes a first tip part 65 including a tip end of the first connection part 60. The second connection part 70 includes a second tip part 75 including a tip end of the second connection part 70. The coupling part 80 and the first connection part 60 are made of the same material. The material of the second tip part 75 is different from the material of the coupling part 80. The length of a shortest path when traveling from a reference position PR to the tip end of the first connection part 60 on a front surface of the coupling part 80 and the first connection part 60 is defined as a first length L1, and the length of the shortest path when traveling from the reference position PR to an end of the second tip end part 75 on the coupling part 80 side on the front surface of the coupling part 80 and the second connection part 70 is defined as a second length L2. The second length L2 is longer than the first length L1.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] The battery pack of Patent Document 1 includes multiple cell batteries and multiple bus bars. The cell batteries are generally cubic-shaped batteries. The cell batteries include a positive terminal and a negative terminal. The positive terminal is located at one end of the cell battery. The positive terminal is made of a metal primarily composed of aluminum. The negative terminal is located at the other end of the cell battery. The negative terminal is made of a metal primarily composed of copper. The multiple cell batteries are arranged so that the orientations of the positive and negative terminals alternate. Therefore, when focusing on two adjacent cell batteries, the positive terminal of the first cell battery and the negative terminal of the second cell battery are adjacent to each other.

[0003] The busbar is generally rectangular. The busbar has a first end portion that is a portion including one end of the busbar, and a second end portion that is a portion other than the first end portion that is the other end of the busbar. The first end portion is made of a metal primarily composed of aluminum. The second end portion is made of a metal primarily composed of copper. The first end portion is connected to the positive terminal of the first cell battery of two adjacent cell batteries. The second end portion is connected to the negative terminal of the second cell battery of two adjacent cell batteries. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2014 / 076817 Summary of the Invention [Problem to be solved by the invention]

[0005] The busbar in Patent Document 1 is composed of a metal primarily composed of aluminum and a metal primarily composed of copper. In such busbars, it may be desirable to reduce the amount of the metal primarily composed of copper compared to the amount of the metal primarily composed of aluminum. However, depending on the shape of the busbar, reducing the amount of the metal primarily composed of copper may complicate the manufacturing process of the busbar. Specifically, when a busbar is composed of multiple metals and the amount of one metal is reduced compared to the amount of the other metal, the manufacturing process of the busbar may become complicated depending on the shape of the busbar. [Means for solving the problem]

[0006] A bus bar for solving the above-described problems includes a plate-shaped connecting portion, a plate-shaped first connection portion extending from the connecting portion toward a specific first direction side parallel to a main surface of the connecting portion, and a plate-shaped second connection portion extending from the connecting portion toward the first direction side, wherein the first connection portion has a first tip portion including a tip of the first connection portion, the second connection portion has a second tip portion including a tip of the second connection portion, the connecting portion and the first connection portion are made of the same material, and the second tip portion of the second connection portion is made of a material different from the material of the connecting portion, and when the end-most position of the edge of the connecting portion in the opposite direction to the first direction is taken as a reference position, the length of the shortest path from the reference position to the tip of the first connecting portion along the surfaces of the connecting portion and the first connecting portion is taken as a first length, and the length of the shortest path from the reference position to the end of the second tip portion on the connecting portion side along the surfaces of the connecting portion and the second connecting portion is taken as a second length, the second length is longer than the first length.

[0007] A battery pack for solving the above problem includes a plurality of bus bars and a plurality of cell batteries, wherein the bus bars include a plate-shaped connecting portion, a plate-shaped first connection portion extending from the connecting portion toward a specific first direction parallel to a main surface of the connecting portion, and a plate-shaped second connection portion extending from the connecting portion toward the first direction, wherein the first connection portion includes a tip of the first connection portion and has a first tip portion that connects to a positive terminal of a first cell battery among the plurality of cell batteries, and the second connection portion includes a tip of the second connection portion and has a second tip portion that connects to a negative terminal of a second cell battery among the plurality of cell batteries, and the connecting portion and the first connection portion are mainly made of aluminum. the positive electrode terminal is made of a metal primarily composed of aluminum, and the material of the second tip portion of the second connection portion is a metal primarily composed of copper, and when a reference position is a position of the endmost edge of the connecting portion in the opposite direction in the opposite direction, and a first length is a length of the shortest path from the reference position to the tip of the first connection portion along the surfaces of the connecting portion and the first connecting portion, and a second length is a length of the shortest path from the reference position to an end of the second tip portion on the connecting portion side along the surfaces of the connecting portion and the second connecting portion, the second length is longer than the first length, the positive electrode terminal is made of a metal primarily composed of aluminum, and the negative electrode terminal is made of a metal primarily composed of copper.

[0008] A method for manufacturing a busbar that solves the above-mentioned problems includes a preparation step of preparing a plate-shaped clad material including a first portion and a second portion, the second portion being made of a material different from the first portion and connected to the first portion; an excision step of cutting an intermediate body from the clad material; and a molding step of shaping the intermediate body into a busbar. In the excision step, a connecting portion, a plate-shaped first connecting portion extending from the connecting portion toward a specific first direction parallel to a main surface of the connecting portion, and a plate-shaped second connecting portion extending from the connecting portion toward the first direction are cut out as a single unit, and the connecting portion and the first connecting portion are all located within the range of the first portion, and only a portion of the second connecting portion including a tip is located within the range of the second portion. [Effects of the Invention]

[0009] According to the above configuration, when manufacturing the busbar, for example, by cutting out the plate material that constitutes the busbar from a plate-shaped clad material in which the first metal and the second metal are arranged side by side, it is possible to use a material that is different from that of the connecting portion, etc. for only a portion including the tip of the second connection portion. Therefore, the process for manufacturing the busbar can be simplified compared to, for example, a case in which two types of metal are cut out separately and then joined together. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a battery pack. [Figure 2] FIG. 2 is a perspective view showing a schematic configuration of a lithium ion secondary battery. [Figure 3] FIG. 3 is an explanatory view showing a part of the electrode assembly in an expanded form. [Figure 4] FIG. 4 is a perspective view showing the peripheral configuration of the bus bar. [Figure 5] FIG. 5 is a cross-sectional view showing the peripheral configuration of the bus bar. [Figure 6] FIG. 6 is a schematic diagram of the manufacturing apparatus. [Figure 7] FIG. 7 is a flowchart showing the manufacturing control. [Figure 8] FIG. 8 is an explanatory diagram showing the cutting step. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Battery pack configuration> An embodiment of the present invention will now be described with reference to Figures 1 to 8. First, the general configuration of a battery pack 100 will be described.

[0012] 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 the positive electrode terminals 13A and negative electrode terminals 13B (described later) are alternately rotated. Therefore, in the two adjacent lithium-ion secondary batteries 10, the positive electrode terminal 13A of the first lithium-ion secondary battery 10 and the negative electrode terminal 13B of the second lithium-ion secondary battery 10 are adjacent to each other. In this embodiment, the lithium-ion secondary batteries 10 are an example of a cell battery. 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.

[0013] 2, the lithium ion secondary battery 10 includes a case 11, a lid 12, a positive electrode terminal 13A, and a negative electrode terminal 13B. 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.

[0014] The case 11 is shaped like a square box with an opening. The opening of the case 11 is shaped like a rectangle. One example of the material of the case 11 is an alloy containing aluminum as a main component, i.e., an aluminum alloy. The lid 12 is shaped like a rectangular plate. One example of the material of the lid 12 is an aluminum alloy. Note that the "main component" here refers to the component with the largest elemental proportion in the material. 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 inside the battery case. That is, the case 11 accommodates the electrode assembly 20 inside the case 11. The electrode assembly 20 will be described in detail later. A nonaqueous electrolyte 31 is stored inside the battery case. That is, the case 11 stores the nonaqueous electrolyte 31 inside the case 11.

[0015] The positive electrode terminal 13A is attached to the lid 12. The position of the positive electrode terminal 13A is shifted to one side of the center of the lid 12 in the longitudinal direction. The positive electrode terminal 13A is connected to the electrode body 20 via a positive electrode current collector 14A. The material of the positive electrode terminal 13A is, for example, an aluminum alloy. The material of the positive electrode current collector 14A is, for example, an aluminum alloy. In this embodiment, the aluminum alloy is an example of a metal containing aluminum as a main component.

[0016] The negative electrode terminal 13B is attached to the lid 12. The negative electrode terminal 13B is located on the opposite side of the longitudinal center of the lid 12 from the positive electrode terminal 13A. The negative electrode terminal 13B is connected to the electrode body 20 via a negative electrode current collector 14B. The material of the negative electrode terminal 13B is, for example, an alloy containing copper as a main component, i.e., a copper alloy. 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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).

[0023] 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).

[0024] 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 for 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.

[0025] 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 a negative electrode terminal 13B via a negative electrode current collector 14B.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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%.

[0032] <Busbar peripheral configuration> 4, the battery pack 100 includes a plurality of bus bars 50. Of two adjacent lithium ion secondary batteries 10, the bus bars 50 connect the positive electrode terminal 13A of a first lithium ion secondary battery 10 to the negative electrode terminal 13B of a second lithium ion secondary battery 10.

[0033] Busbar 50 includes a first connection portion 60, a second connection portion 70, and a linking portion 80. Busbar 50 has an overall shape obtained by bending and curving a plate at multiple locations.

[0034] As shown in Figure 4, the connecting portion 80 has a rectangular plate shape as a whole. In the following, a specific direction along the long side of the connecting portion 80 is referred to as the left direction DL, and the opposite direction is referred to as the right direction DR. Furthermore, a specific direction perpendicular to the left direction DL and along the short side of the connecting portion 80 is referred to as the forward direction DF, and the opposite direction is referred to as the back direction DB. Furthermore, a specific direction perpendicular to both the left direction DL and the forward direction DF is referred to as the upward direction DP, and the opposite direction is referred to as the downward direction DN.

[0035] The connecting portion 80 includes a first connecting portion 81, a second connecting portion 82, and a curved portion 83. An example of the material for the first connecting portion 81, the second connecting portion 82, and the curved portion 83 is an aluminum alloy. The first connecting portion 81, the curved portion 83, and the second connecting portion 82 are arranged in this order in the right direction DR.

[0036] The first connecting portion 81 includes an insertion hole 81A. The insertion hole 81A penetrates the first connecting portion 81 in the thickness direction of the first connecting portion 81. The insertion hole 81A is used to attach a peripheral component such as a sensor to the bus bar 50. The curved portion 83 is connected to an edge of the first connecting portion 81 in the right direction DR. When the bus bar 50 is viewed in the depth direction DB, the curved portion 83 is curved so as to convexly extend downward in the downward direction DN. The second connecting portion 82 is connected to an edge of the curved portion 83 in the right direction DR. The second connecting portion 82 includes an insertion hole 82A. The insertion hole 82A penetrates the second connecting portion 82 in the thickness direction of the second connecting portion 82. The insertion hole 82A is used to attach a peripheral component such as a sensor to the bus bar 50. A main surface of the second connecting portion 82 is located on the same imaginary plane as a main surface of the first connecting portion 81. Therefore, the principal surface of the first connecting portion 81 and the principal surface of the second connecting portion 82 are aligned in the upward direction DP. The principal surfaces of the first connecting portion 81 and the second connecting portion 82 are the principal surfaces of the connecting portion 80. The forward direction DF is an example of a specific first direction parallel to the principal surface of the connecting portion 80.

[0037] The first connecting portion 60 extends from the connecting portion 80 toward the front direction DF. The first connecting portion 60 includes a first intermediate portion 61 and a first tip portion 65. One example of the material for the first intermediate portion 61 and the first tip portion 65 is an aluminum alloy. The first intermediate portion 61 and the first tip portion 65 are arranged in this order from the connecting portion 80 toward the front direction DF. In this embodiment, the first tip portion 65 is a portion of the first connecting portion 60 that includes the tip.

[0038] The first intermediate portion 61 includes a base-end connecting plate 62 and a tip-end standing plate 63. The base-end connecting plate 62 extends in the front direction DF from an edge of the first connecting portion 81 of the connecting part 80 in the front direction DF. The tip-end standing plate 63 extends in the downward direction DN from an edge of the base-end connecting plate 62 in the front direction DF. Therefore, the first intermediate portion 61 as a whole has a shape that is bent at approximately 90 degrees midway.

[0039] The first tip portion 65 extends in the front direction DF from the edge of the tip-side standing plate 63 of the first intermediate portion 61 in the downward direction DN. That is, the first tip portion 65 is connected to the connecting portion 80 via the first intermediate portion 61. In other words, the first intermediate portion 61 connects the connecting portion 80 and the first tip portion 65.

[0040] The first tip portion 65 has a generally rectangular plate shape. The main surface of the first tip portion 65 is parallel to the main surface of the connecting portion 80 and is located on the downward direction DN side of the main surface of the connecting portion 80. Furthermore, when the bus bar 50 is attached to the lithium ion secondary battery 10, the main surface of the first tip portion 65 is parallel to the main surface of the lid body 12 of the lithium ion secondary battery 10.

[0041] The first tip portion 65 has a recess 66 and an insertion hole 67. The recess 66 is recessed in the downward direction DN relative to other portions of the first tip portion 65. The recess 66 is located approximately in the center of the first tip portion 65. The insertion hole 67 penetrates the first tip portion 65 in the thickness direction of the first tip portion 65. The insertion hole 67 is located approximately in the center of the recess 66. The positive electrode terminal 13A of the lithium ion secondary battery 10 is inserted into the insertion hole 67 of the first tip portion 65 of the bus bar 50. The positive electrode terminal 13A of the lithium ion secondary battery 10 and the first tip portion 65 of the bus bar 50 are connected by welding.

[0042] The second connecting portion 70 extends from the connecting portion 80 toward the front direction DF. The second connecting portion 70 is located in the right direction DR relative to the first connecting portion 60. The second connecting portion 70 includes a second intermediate portion 71 and a second tip portion 75. An example of the material of the second intermediate portion 71 is an aluminum alloy. That is, the second intermediate portion 71, the connecting portion 80, and the first connecting portion 60 are made of the same material. The second intermediate portion 71 and the second tip portion 75 are arranged in this order from the connecting portion 80 toward the front direction DF. In this embodiment, the second tip portion 75 is a portion of the second connecting portion 70 that includes the tip.

[0043] The second intermediate portion 71 includes a base-side standing plate 72, a central connecting plate 73, and a tip-side standing plate 74. The base-side standing plate 72 extends in the upward direction DP from an edge of the second connecting portion 82 of the connecting portion 80 in the front direction DF. The central connecting plate 73 extends in the forward direction DF from an edge of the base-side standing plate 72 in the upward direction DP. The tip-side standing plate 74 extends in the downward direction DN from an edge of the central connecting plate 73 in the front direction DF. Therefore, the second intermediate portion 71 as a whole is curved so as to be convex in the upward direction DP with respect to the connecting portion 80.

[0044] The second tip portion 75 extends from the edge of the tip-side standing plate 74 of the second intermediate portion 71 in the downward direction DN toward the front direction DF. That is, the second tip portion 75 is connected to the connecting portion 80 via the second intermediate portion 71. In other words, the second intermediate portion 71 connects the connecting portion 80 and the second tip portion 75. Furthermore, the second intermediate portion 71 is curved so as to be convex toward the upward direction DP with respect to the second tip portion 75. In this embodiment, the upward direction DP is an example of a second direction perpendicular to the main surface of the connecting portion 80.

[0045] The second tip portion 75 has a generally rectangular plate shape. The main surface of the second tip portion 75 is parallel to the main surface of the connecting portion 80 and is located on the downward direction DN side of the main surface of the connecting portion 80. Furthermore, when the bus bar 50 is attached to the lithium ion secondary battery 10, the main surface of the second tip portion 75 is parallel to the main surface of the lid body 12 of the lithium ion secondary battery 10. In other words, the main surface of the second tip portion 75 is parallel to the main surface of the first tip portion 65.

[0046] The second tip portion 75 includes a recess 76 and an insertion hole 77. The recess 76 is recessed in the downward direction DN relative to the other portions of the second tip portion 75. The recess 76 is located approximately in the center of the second tip portion 75. The insertion hole 77 penetrates the second tip portion 75 in the thickness direction of the second tip portion 75. The insertion hole 77 is located approximately in the center of the recess 76. As shown in FIG. 5 , the negative electrode terminal 13B of the lithium ion secondary battery 10 is inserted into the insertion hole 77 of the second tip portion 75 of the bus bar 50. The negative electrode terminal 13B of the lithium ion secondary battery 10 and the second tip portion 75 of the bus bar 50 are connected by welding. An example of a material for the second tip portion 75 is a copper alloy. That is, the material for the second tip portion 75 is different from the materials for the first connecting portion 60, the coupling portion 80, and the second intermediate portion 71.

[0047] When the bus bar 50 is viewed in the left direction DL, the second tip 75 of the second connection portion 70 overlaps with the first tip 65 of the first connection portion 60. More specifically, in this embodiment, the first tip 65 and the second tip 75 are aligned in the forward direction DF. Furthermore, the first tip 65 and the second tip 75 are aligned in the upward direction DP.

[0048] As shown in FIG. 4 , the position of the end of the connecting portion 80 in the depth direction DB is defined as a reference position PR. In this embodiment, the depth direction DB edge of the first connecting portion 81 and the depth direction DB edge of the second connecting portion 82 are aligned in the depth direction DB. Therefore, each of the depth direction DB edges of the first connecting portion 81 and the depth direction DB edges of the second connecting portion 82 is defined as a reference position PR. The position of the tip of the first connecting portion 60 is defined as a first comparison position P1. Specifically, the first comparison position P1 is the position of the edge of the first tip portion 65 of the first connecting portion 60 in the front direction DF. The position of the end of the second tip portion 75 of the second connecting portion 70 on the connecting portion 80 side is defined as a second comparison position P2. Specifically, the second comparison position P2 is the position of the edge of the second tip portion 75 of the second connecting portion 70 in the depth direction DB. As shown by the dashed-dotted arrow in Fig. 4, the length of the shortest path from the reference position PR to the first comparison position P1 along the surfaces of the linking portion 80 and the first connecting portion 60 is defined as a first length L1. Also, as shown by the dashed-dotted arrow in Fig. 4, the length of the shortest path from the reference position PR to the second comparison position P2 along the surfaces of the linking portion 80 and the second connecting portion 70 is defined as a second length L2. In this case, the second length L2 is longer than the first length L1.

[0049] Assume that the entire busbar 50 is developed into a flat plate. In this case, the first length L1 is equal to the shortest distance from the reference position PR to the first comparison position P1 when the busbar 50 is viewed in a plan view. Similarly, the second length L2 is equal to the shortest distance from the reference position PR to the second comparison position P2 when the busbar 50 is viewed in a plan view. In other words, as shown in FIG. 8, the first length L1 and the second length L2 indicate dimensions at a stage before the plate material is formed into the busbar 50 in the manufacturing control described below.

[0050] <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 bus bar 50.

[0051] 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 bus bar 50. Here, the various types of equipment are used in manufacturing control, which will be described later. The input device 220 includes, for example, a keyboard and a pointing device. The display 230 is capable of displaying various types of information.

[0052] 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 processes related to the manufacturing method of the busbar 50.

[0053] 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 bus bar 50 using the manufacturing equipment 210.

[0054] <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 bus bar 50. 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.

[0055] As shown in FIG. 7 , when the execution unit 291 of the manufacturing management device 290 starts manufacturing control, it executes the process of step S11. In step S11, the execution unit 291 executes a preparation process of preparing a clad material 300. Specifically, the execution unit 291 uses the manufacturing equipment 210 to set the clad material 300 in a predetermined location so that the clad material 300 can be used in step S12, which will be described later. As shown in FIG. 8 , the clad material 300 is a plate-shaped material in which a first portion 310, a second portion 320, and a third portion 330 are arranged side by side. The first portion 310 has a rectangular plate shape. An example of a material for the first portion 310 is an aluminum alloy. The second portion 320 has a rectangular plate shape. One of the two long sides of the second portion 320 is connected to the long side of the first portion 310. An example of a material for the second portion 320 is a copper alloy. That is, the material of the second portion 320 is different from the material of the first portion 310. Furthermore, the material of the second portion 320 is the same as the material of the second tip portion 75. The third portion 330 has a rectangular plate shape. The long side of the third portion 330 is connected to the other of the two long sides of the second portion 320. Therefore, the third portion 330 is connected to the second portion 320 on the opposite side of the second portion 320 from the first portion 310. An example of the material of the third portion 330 is an aluminum alloy. That is, the material of the third portion 330 is the same as the material of the first portion 310. Furthermore, the materials of the first portion 310 and the third portion 330 are the same as the materials of the first connecting portion 60, the connecting portion 80, and the second intermediate portion 71. Note that in this embodiment, the clad material 300 is a so-called roll material in which a plate-shaped material is wound. As shown in FIG. 7, after step S11, the execution device 291 advances the process to step S12.

[0056] In step S12, the executing unit 291 executes a cutting step of cutting out a plurality of intermediate bodies 50Z from the clad material 300. Specifically, the executing unit 291 uses the manufacturing equipment 210 to integrally cut out portions of the bus bar 50 corresponding to the first connecting portion 60, the second connecting portion 70, and the linking portion 80 as intermediate bodies 50Z from the clad material 300. At this time, as indicated by the two-dot chain line in FIG. 8 , the executing unit 291 uses the manufacturing equipment 210 to cut out a pair of intermediate bodies 50Z, one first intermediate body 50ZA and one second intermediate body 50ZB as a set. The first intermediate body 50ZA is an intermediate body 50Z in which the portions corresponding to the first connecting portion 60, the linking portion 80, and the second intermediate portion 71 are located within the range of the first portion 310, and the portion corresponding to the second tip portion 75 is located within the range of the second portion 320. The second intermediate 50ZB is an intermediate 50Z in which the portions corresponding to the first connecting portion 60, the connecting portion 80, and the second intermediate portion 71 are located within the range of the third portion 330, and the portion corresponding to the second tip portion 75 is located within the range of the second portion 320. In this embodiment, the first intermediate 50ZA and the second intermediate 50ZB are located point-symmetrically. Note that in FIG. 8, only the outer shape of the member corresponding to the bus bar 50 is illustrated as the intermediate 50Z. As shown in FIG. 7, after step S12, the executing unit 291 advances the process to step S13.

[0057] In step S13, the executing unit 291 executes a forming process of forming the intermediate body 50Z into the bus bar 50. Specifically, the executing unit 291 forms the bus bar 50 by bending the intermediate body 50Z using the manufacturing equipment 210. After step S13, the executing unit 291 ends the current manufacturing control.

[0058] <Operation of this embodiment> 4, the second length L2 of the bus bar 50 is longer than the first length L1 of the bus bar 50. Therefore, as shown in FIG. 8, when the intermediate body 50Z is cut out from the clad material 300 in the cutting process of step S12 in the manufacturing control, the second length L2 is also longer than the first length L1.

[0059] <Effects of this embodiment> (1) According to this embodiment, in the cutting process of step S12 in the manufacturing control, by cutting out only the portion corresponding to second tip portion 75 within the range of second portion 320, it is possible to use a material for only second tip portion 75 that is different from that for connecting portion 80, etc. As a result, the process for manufacturing bus bar 50 can be simplified compared to, for example, a case in which two types of metal are cut out and then joined together. Note that if the process for manufacturing bus bar 50 can be simplified in this way, it is expected that the manufacturing cost of bus bar 50 can be reduced, for example.

[0060] (2) In the bus bar 50, the second portion 320 of the clad material 300 is used only as material for the second tip portion 75. Therefore, if the configuration of the above embodiment is not adopted, there is a tendency for material loss of the second portion 320 to be large in the cutting process of step S12. In this regard, in the cutting process of step S12 in the manufacturing control, as shown in FIG. 8 , the executing unit 291 uses the manufacturing equipment 210 to cut out a pair of intermediate bodies 50Z, a first intermediate body 50ZA and a second intermediate body 50ZB. This makes it possible to effectively utilize the second portion 320 of the clad material 300. This reduces material loss of the second portion 320 of the clad material 300.

[0061] (3) The second intermediate portion 71 of the busbar 50 is curved so as to be convex in the upward direction DP relative to the second tip portion 75. Therefore, a step is formed between the second intermediate portion 71 and the second tip portion 75. As a result, when assembling components of the battery pack 100, for example, the step between the second intermediate portion 71 and the second tip portion 75 comes into contact with the peripheral components of the busbar 50, as shown by the dashed dotted line in FIG. 5 , thereby restricting movement of the peripheral components of the busbar 50 relative to the busbar 50. As a result, when assembling the busbar 50 and the peripheral components of the busbar 50, it is possible to prevent the peripheral components of the busbar 50 from becoming misaligned relative to the busbar 50.

[0062] (4) The second intermediate portion 71 of the busbar 50 is curved so as to be convex in the upward direction DP with respect to the connecting portion 80. Therefore, a step is formed between the second intermediate portion 71 and the connecting portion 80. As a result, when assembling the components of the battery pack 100, for example, the step between the second intermediate portion 71 and the connecting portion 80 comes into contact with the peripheral components of the busbar 50, as shown by the two-dot chain line in FIG. 5 , thereby restricting movement of the peripheral components of the busbar 50 relative to the busbar 50. As a result, when assembling the busbar 50 and the peripheral components of the busbar 50, it is possible to prevent the peripheral components of the busbar 50 from becoming misaligned with respect to the busbar 50.

[0063] (5) The second intermediate portion 71 of the busbar 50 is curved so as to be convex in the upward direction DP with respect to the second tip portion 75 and the connecting portion 80. By curving the second intermediate portion 71 in this manner, the second length L2 of the busbar 50 can be made longer than the first length L1 with a relatively simple configuration.

[0064] (6) The positive electrode terminal 13A of the lithium ion secondary battery 10 is made of an aluminum alloy. The negative electrode terminal 13B of the lithium ion secondary battery 10 is made of a copper alloy. In general, the electrical resistance of an aluminum alloy is greater than that of a copper alloy. Therefore, when electricity is flowing, the amount of heat generated by the aluminum alloy is greater than that of the copper alloy. Therefore, when electricity is flowing, the temperature of the positive electrode terminal 13A is higher than that of the negative electrode terminal 13B.

[0065] In this regard, as shown in FIG. 4 , a first end portion 65 of a first connection portion 60 of the busbar 50 is connected to the positive electrode terminal 13A of the lithium-ion secondary battery 10. A second end portion 75 of a second connection portion 70 of the busbar 50 is connected to the negative electrode terminal 13B of the lithium-ion secondary battery 10. The second length L2 of the busbar 50 is longer than the first length L1 of the busbar 50. Therefore, the electrical resistance of the second connection portion 70 of the busbar 50 is larger than when, for example, the second length L2 is the same as the first length L1. This increases the amount of heat generated by the second connection portion 70 connected to the negative electrode terminal 13B when electricity is flowing. As a result, even if the temperature of the positive electrode terminal 13A becomes higher than that of the negative electrode terminal 13B when electricity is flowing, the difference in temperature between the connection point of the linking portion 80 and the first connection portion 60 and the connection point of the linking portion 80 and the second connection portion 70 can be prevented from becoming excessively large. If the difference between the two temperatures can be suppressed as described above, it is possible to prevent problems such as a decrease in the output of the battery pack 100 due to an increase in the difference between the two temperatures.

[0066] <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.

[0067] In the above embodiment, the configuration of the battery pack 100 may be changed. For example, the cell battery is not limited to the lithium ion secondary battery 10. That is, the bus bar 50 may be applicable to batteries other than the lithium ion secondary battery 10. In this case, it is preferable to select the material of the bus bar 50 in accordance with the material of the positive and negative terminals of the cell battery to which the bus bar 50 is connected.

[0068] In the above embodiment, the configuration of the bus bar 50 may be changed. For example, the second intermediate portion 71 of the busbar 50 may be curved so as to convex in the downward direction DN relative to the second tip portion 75. As a specific example, depending on the position of the negative electrode terminal 13B of the lithium ion secondary battery 10 in the upward direction DP, the second intermediate portion 71 of the busbar 50 may be curved so as to convex in the downward direction DN relative to the second tip portion 75.

[0069] For example, the second intermediate portion 71 of the busbar 50 may be curved so as to convex in the downward direction DN with respect to the connecting portion 80. As a specific example, depending on the position of the negative electrode terminal 13B of the lithium-ion secondary battery 10 in the upward direction DP, the second intermediate portion 71 of the busbar 50 may be curved so as to convex in the downward direction DN with respect to the connecting portion 80.

[0070] For example, the second intermediate portion 71 of the busbar 50 does not have to be curved so as to convex in the upward direction DP or the downward direction DN relative to the second tip portion 75. As a specific example, if the positions of the first tip portion 65 and the second tip portion 75 in the upward direction DP are misaligned, or if the positions of the first connecting portion 81 and the second connecting portion 82 in the upward direction DP are misaligned, the positions of the central connecting plate 73 and the second tip portion 75 in the upward direction DP may be aligned. In other words, the second intermediate portion 71 of the busbar 50 does not have to be curved so as to convex in the upward direction DP or the downward direction DN relative to the second tip portion 75. Note that if the positions of the positive electrode terminal 13A and the negative electrode terminal 13B of the lithium-ion secondary battery 10 are misaligned in the upward direction DP, the positions of the first tip portion 65 and the second tip portion 75 in the upward direction DP may be misaligned.

[0071] For example, the second intermediate portion 71 of the busbar 50 does not have to be curved so as to be convex in the upward direction DP or the downward direction DN with respect to the connecting portion 80. As a specific example, if the positions of the first tip end 65 and the second tip end 75 in the upward direction DP are misaligned, or the positions of the first connecting portion 81 and the second connecting portion 82 in the upward direction DP are misaligned, the positions of the central connecting plate 73 and the second connecting portion 82 in the upward direction DP may be aligned. In other words, the second intermediate portion 71 of the busbar 50 does not have to be curved so as to be convex in the upward direction DP or the downward direction DN with respect to the connecting portion 80.

[0072] For example, the materials of the second intermediate portion 71, the connecting portion 80, and the first connecting portion 60 are not limited to metals primarily composed of aluminum and can be changed. In this case, the materials of the first portion 310 and the third portion 330 of the clad material 300 may be changed to match the materials of the second intermediate portion 71, the connecting portion 80, and the first connecting portion 60.

[0073] For example, the material of the second tip portion 75 is not limited to a metal mainly composed of copper and can be changed. In this case, the material of the second portion 320 of the clad material 300 may be changed to match the material of the second tip portion 75.

[0074] In the above embodiment, the manufacturing control may be changed. For example, in the cutting process of step S12, the executing unit 291 may cut out one intermediate body 50Z instead of the pair of intermediate bodies 50Z using the manufacturing equipment 210. In this case, the clad material 300 may be a plate-shaped material in which only the first portion 310 and the second portion 320 are arranged. [Explanation of symbols]

[0075] 10...Lithium-ion secondary battery 11...Case 12...lid body 13A...Positive terminal 13B...Negative terminal 14A...Positive electrode current collecting member 14B...Negative electrode current collecting member 20...Electrode body 40...Spacer 50...busbar 50Z...Intermediate 60...First connection part 61...First intermediate section 65...First tip 67...insertion hole 70...Second connection part 71...Second intermediate section 75…Second tip 77...insertion hole 80…Connection part 90...Storage case 90A...Storage space 100...Battery pack 200...Manufacturing equipment 210…Manufacturing equipment 290...Manufacturing control equipment 300...Clad material 310…First part 320…Second part 330...Third part

Claims

1. A plate-shaped connecting part, a plate-shaped first connection portion extending from the coupling portion toward a specific first direction parallel to a main surface of the coupling portion; a plate-shaped second connection portion extending from the coupling portion toward the first direction side, the first connection portion has a first tip portion including a tip of the first connection portion, the second connection portion has a second tip portion including a tip of the second connection portion, The material of the connecting portion and the material of the first connecting portion are the same, the material of the second tip portion of the second connecting portion is different from the material of the connecting portion; When the position of the endmost edge of the edge of the connecting portion in the opposite direction to the first direction is defined as a reference position, the length of the shortest path from the reference position to the tip of the first connecting portion when traveling along the surfaces of the connecting portion and the first connecting portion is defined as a first length, and the length of the shortest path from the reference position to the end of the second tip portion on the connecting portion side when traveling along the surfaces of the connecting portion and the second connecting portion is defined as a second length, The second length is greater than the first length. Busbar.

2. the second connecting portion has a second intermediate portion connecting the coupling portion and the second tip portion, The second intermediate portion is curved relative to the second tip portion so as to be convex toward a second direction perpendicular to the main surface or toward a direction opposite to the second direction. The busbar of claim 1 .

3. the second connecting portion has a second intermediate portion connecting the coupling portion and the second tip portion, The second intermediate portion is curved relative to the connecting portion so as to be convex in a second direction perpendicular to the main surface or in a direction opposite to the second direction. The busbar of claim 1 .

4. a plurality of bus bars; a plurality of cell batteries; The bus bar is A plate-shaped connecting part, a plate-shaped first connection portion extending from the coupling portion toward a specific first direction parallel to a main surface of the coupling portion; a plate-shaped second connection portion extending from the coupling portion toward the first direction side, the first connection portion includes a tip end of the first connection portion and has a first tip portion that connects to a positive terminal of a first cell battery among the plurality of cell batteries; the second connection portion includes a tip end of the second connection portion and has a second tip end portion that connects to a negative terminal of a second cell battery among the plurality of cell batteries; the connecting portion and the first connecting portion are made of a metal containing aluminum as a main component, the second tip portion of the second connection portion is made of a metal containing copper as a main component, When the position of the endmost edge of the edge of the connecting portion in the opposite direction to the first direction is defined as a reference position, the length of the shortest path from the reference position to the tip of the first connecting portion when traveling along the surfaces of the connecting portion and the first connecting portion is defined as a first length, and the length of the shortest path from the reference position to the end of the second tip portion on the connecting portion side when traveling along the surfaces of the connecting portion and the second connecting portion is defined as a second length, the second length is greater than the first length; The material of the positive electrode terminal is a metal containing aluminum as a main component, The material of the negative electrode terminal is a metal containing copper as a main component. Battery pack.

5. a preparation step of preparing a plate-shaped clad material including a first portion and a second portion made of a different material from the first portion and connected to the first portion; a cutting step of cutting an intermediate body from the clad material; a molding step of molding the intermediate body into a bus bar; Equipped with In the cutting step, a connecting portion, a plate-like first connecting portion extending from the connecting portion toward a specific first direction side parallel to a main surface of the connecting portion, and a plate-like second connecting portion extending from the connecting portion toward the first direction side, The cutting is performed so that the connecting portion and the first connecting portion are all located within the range of the first portion, and only a portion including a tip of the second connecting portion is located within the range of the second portion. Busbar manufacturing method.

6. In the preparation step, preparing a plate-shaped clad material including the first portion, the second portion, and a third portion made of the same material as the first portion and connected to the second portion on the opposite side of the first portion with the second portion sandwiched therebetween; In the cutting step, A pair of intermediate bodies is cut out, the pair being a first intermediate body in which the connecting portion and the first connecting portion are all located within the range of the first portion, and only a portion including the tip of the second connecting portion is located within the range of the second portion, and a second intermediate body in which the connecting portion and the first connecting portion are all located within the range of the third portion, and only a portion including the tip of the second connecting portion is located within the range of the second portion. The method for manufacturing the bus bar according to claim 5 .

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