Secondary battery, secondary battery module, and method for manufacturing secondary battery

Abstract

To provide a secondary battery that prevents breakage of a collector tab caused by metal members and prevents an increase in internal resistance, a secondary battery module, and a method for manufacturing a secondary battery.SOLUTION: A secondary battery of an embodiment has an electrode group that includes an active material carrying part carrying an active material on a metal foil and having, at least at one end, a plurality of layers of collector tabs sandwiched by metal members, and a lead that is welded to at least part of the metal members. The metal member has a first plate part that is welded to at least part of one face of the collector tabs, and a second plate part that is welded to at least part of the other face of the collector tabs. At least either one of the first plate part or the second plate part has a contact part that is brought into contact with the collector tabs, one or more bent parts that are formed in a direction away from the collector tabs, and a slit part that is provided between the contact part and the bent parts.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a secondary battery, a secondary battery module, and a method for manufacturing a secondary battery. do. [Background technology]

[0002] In recent years, the use of electric vehicles, hybrid vehicles, electric motorcycles, and forklifts has become increasingly common. Secondary batteries such as lead-acid batteries and nickel-metal hydride batteries are used as power sources for these devices. In the US, development efforts are underway to adopt high-energy-density lithium-ion secondary batteries. The development is being carried out with consideration given to long life and safety.

[0003] A typical lithium ion secondary battery (hereinafter referred to as a secondary battery) has a positive electrode and an electrode group in which a negative electrode is wound and each electrode group has a current collecting tab at one end of the winding in the axial direction; There are secondary batteries with positive and negative electrode leads that are connected to tabs. In this case, when joining the current collecting tab and the lead, the current collecting tab is made of a material that makes it easier to weld the two together. In some cases, a metal member is used to bundle the blocks together.

[0004] Such secondary batteries are used for a variety of purposes. For example, when they are installed in a vehicle, The secondary battery vibrates due to the vibrations during use. This vibration causes the edges of the metal parts to rub against the current collecting tabs. As a result, the current collecting tabs are scratched, and if this rubbing continues, the current collecting tabs may break. If the current collecting tab breaks, the current will flow around the broken part, and the secondary current will The internal resistance of the battery increases, which deteriorates the current characteristics and low-temperature characteristics, causing capacity degradation.

[0005] In addition, secondary batteries are generally required to have high capacity, but there are many ways to increase the capacity. As a step, in order to increase the mass of the electrode active material, the size of the electrode group is increased, and One option is to increase the number of windings, but this would make the electrode group heavier. Therefore, the damage caused by the above-mentioned friction increases in proportion to the weight of the electrode group, and the current collecting tabs are likely to break. It becomes easier. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-4222 [Patent Document 2] Patent No. 6159719 Summary of the Invention [Problem to be solved by the invention]

[0007] The problem to be solved by the present invention is to provide a metal member that is in contact with at least a part of the current collecting tab. Therefore, the secondary battery, secondary battery module, and secondary battery module can be prevented from breaking. The present invention provides a method for manufacturing a secondary battery. [Means for solving the problem]

[0008] In order to achieve the above object, the secondary battery of the embodiment is an active material supported on a metal foil. The battery includes a metal support portion and has a plurality of current collecting tabs sandwiched by a metal member at at least one end. an electrode group; The metal member has a lead welded to at least a portion of the metal member. a first plate portion welded to at least a portion of one surface of the current collecting tab; and a second plate portion welded to at least a part of the first plate portion or the second plate portion. At least one of them has a contact portion that is in contact with the current collecting tab and a contact portion that is spaced apart from the current collecting tab. One or more curved portions formed in a direction parallel to the contact portion, and a groove provided between the contact portion and the curved portion. It has a nut section. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view schematically showing a secondary battery according to a first embodiment. [Figure 2] 1 is a perspective view schematically showing a secondary battery according to a first embodiment in a state where each component is disassembled; [Figure 3] FIG. 2 is a development view of a metal member in the secondary battery according to the first embodiment. [Figure 4] 1 is a perspective view schematically showing the periphery of an electrode group in a secondary battery according to a first embodiment. [Figure 5] 5 is a cross-sectional view of the secondary battery according to the first embodiment taken along line II in FIG. 4 in the Z direction, and is a cross-sectional view schematically showing the periphery of a metal member. FIG. [Figure 6] 5 is a cross-sectional view of the secondary battery according to the first embodiment taken along line II in FIG. 4 in the Z direction, and is an enlarged view of a metal member. [Figure 7] 5 is a partial cross-sectional view of the secondary battery according to the first embodiment, taken along line II-II in FIG. 4 in the Z direction. [Figure 8] 5 is a partial cross-sectional view of the secondary battery according to the first embodiment taken along line II in FIG. 4 in the Z direction, and is a cross-sectional view schematically showing the periphery of a metal member. FIG. [Figure 9] 5 is a partial cross-sectional view of the secondary battery according to the first embodiment taken along line II in FIG. 4 in the Z direction, and is a cross-sectional view schematically showing the periphery of a metal member. FIG. [Figure 10] 5 is a partial cross-sectional view of the secondary battery according to the first embodiment taken along line II in FIG. 4 in the Z direction, and is a cross-sectional view schematically showing the periphery of a metal member. FIG. [Figure 11] FIG. 10 is a perspective view schematically showing a secondary battery module according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a secondary battery, a secondary battery module, and a method of manufacturing a secondary battery according to the embodiments will be described with reference to the drawings. This will be explained in light of the above.

[0011] (First embodiment) A secondary battery 1 of the first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view showing a secondary battery 1 according to an embodiment; FIG. 2 is a perspective view showing a secondary battery 1 according to a first embodiment; 1 and 2 are perspective views each showing a schematic exploded view of the device 1. The secondary battery 1 includes an outer case 3 and an electrode group 5. The outer case 3 has, for example, a side wall and a bottom wall. The outer case 3 has an internal cavity therein, and the outer case 3 has a cylindrical shape. An opening 9 is provided in the exterior case. For example, a cover member 7 is disposed in the exterior case opening 9. The case 3 and the cover member 7 are made of aluminum, aluminum alloy, iron, copper, stainless steel, etc. The secondary battery 1 is formed from a metal. It is sufficient that the secondary battery 1 has an outer case 3 and an electrode group 5. As in the embodiment, the bottom wall and the outer case opening 9 are not limited to a rectangular shape. 3 is not limited to a cylindrical shape.

[0012] The electrode group 5 is housed in the internal cavity of the exterior case 3. Here, the electrode group 5 is housed in the exterior case 3. The step of storing the electrode group 5 is referred to as a storing step. After sandwiching a separator (not shown) and winding it around the shaft, the whole is pressure-molded into a flat shape. The positive electrode 13 is manufactured by forming a positive electrode current collector 13a and a conductive film on one side or both sides of the positive electrode current collector 13a. The positive electrode current collector 1 has a positive electrode active material support portion (not shown) supported on both sides. The positive electrode current collector 13a has a positive electrode active material supporting portion as an uncoated portion. On the other hand, the negative electrode 15 has a negative electrode current collector 15a and a negative electrode current collector 15a. The negative electrode has a negative electrode active material support portion (not shown) supported on one or both sides. The negative electrode current collector 15a is a metal foil. The negative electrode active material supporting portion of the negative electrode current collector 15a is an uncoated portion. The electrode group 5 includes a plurality of positive electrodes 13 and a plurality of negative electrodes 15. The positive electrode 13 and the negative electrode 15 are alternately stacked, and a separator is provided between the positive electrode 13 and the negative electrode 15. The structure is not limited to a wound structure or a stack structure. When using an electrode group 5 having a stack structure rather than a laminated structure, the connection structure with the exterior case 3 should be appropriately Change.

[0013] In this embodiment, the electrode group 5 is a wound body, and at least one end of the electrode group 5 has a plurality of layers In this embodiment, a positive electrode current collecting tab 70a and a negative electrode current collecting tab 70b are provided. The negative electrode current collecting tab 70a protrudes in the opposite direction to the protruding direction of the negative electrode current collecting tab 70b. Current collecting tabs 70 are provided at the ends of the positive electrode current collecting tab 70a and the negative electrode current collecting tab 70b. The protruding direction is not limited to these. For example, both current collecting tabs 70 may protrude in the same direction, and the current A current collecting tab 70 may be provided at one end of the pole group 5. Each of the multiple layers of current collecting tabs 70 is sandwiched between the positive electrode metal member 16a and the negative electrode metal member 16b. This means that the metal member 16 bundles and integrates a plurality of layers of current collecting tabs 70, and the current collecting tabs 7 At least a part of the metal member 16 may be in contact with one surface and the other surface of the metal member 16. .

[0014] As in this embodiment, the electrode group 5 has a wound structure, and current collecting tabs 70 are attached to both ends of the electrode group 5. If provided, each of the current collecting tabs 70 on both ends is sandwiched between two or more metal members 16. This is preferable as a means for increasing the capacity of a secondary battery, for example. Even if the weight of the electrode group 5 is increased, the current collecting tab 70 can be stably held by the metal member 16. Here, increasing the weight of the electrode group 5 means increasing the mass of the electrode active material. This is the case when the size of the group is increased or when the number of windings of the electrodes is increased. The number of metal members 16 arranged on each of the current collecting tabs 70 is not limited to these, and the number of metal members 16 arranged on each of the current collecting tabs 70 is not limited to these. At least one of the current collecting tabs 70 at both ends of the terminal 5 may be sandwiched between one or more metal members 16.

[0015] The positive electrode 13 is formed by applying a slurry containing a positive electrode active material to an aluminum foil or an aluminum alloy foil. The cathode active material is lithium. Examples include oxides, sulfides, and polymers thereof that can absorb and release cations. The positive electrode active material is not limited to these. Preferred positive electrode active materials are lithium manganese composite oxide, Lithium nickel composite oxide, lithium cobalt composite oxide, and lithium iron phosphate, etc. Examples include:

[0016] The negative electrode 15 is formed by applying a slurry containing a negative electrode active material to an aluminum foil, an aluminum alloy foil, or a copper foil. The negative electrode active material is produced by applying it to the negative electrode current collector 15a made of foil or the like. Metal oxides, metal sulfides, metal nitrides, and carbon materials that can absorb and release lithium ions The preferred negative electrode active material is titanium dioxide. materials, lithium titanium oxide, niobium titanium oxide, niobium oxide, tungsten oxide, Examples include amorphous tin oxide, tin silicon oxide, silicon oxide, and silicon.

[0017] Inside the exterior case 3, the electrode group 5 is impregnated with an electrolyte (not shown). For example, the electrolyte is poured through a pouring hole 17 provided in the cover member 7, and the pouring hole 17 is sealed after the electrolyte is poured. The electrode is closed by a stop plate 19. The electrolyte solution is a solution of an electrolyte (e.g., a lithium salt) dissolved in a non-aqueous solvent. The non-aqueous solvent may be used alone or in combination of two or more. They may be used in combination.

[0018] On the surface of the lid member 7, a liquid injection port 17 and a gas exhaust valve 21 are formed. The opening 17 and the gas exhaust valve 21 do not have to be provided on the cover member 7. For example, a pair of external terminals 23 are attached to the external terminals 23, and the external terminals 23 are made of a conductive material such as metal. One of the external terminals 23 is a positive external terminal 23a, and the other is a negative external terminal 23b. The external terminal 23 is disposed in close contact with the cover member 7 via an insulating gasket 29. The positive electrode external terminal 23a and the negative electrode external terminal 23b are further connected to a positive electrode lead 31a and a negative electrode lead 31b. 31b.

[0019] The positive electrode lead 31a and the negative electrode lead 31b are connected to the positive electrode current collecting tab 70a and the negative electrode current collecting tab 70b is joined to the sandwiched positive electrode metal member 16a and negative electrode metal member 16b, and the electrode group 5 The lead 31 is electrically connected to the external terminal 23. Furthermore, an internal insulator is provided between the cover member 7 and the lead 31. An edge member 33 may be provided to electrically insulate the cover member 7 from the leads 31. The leads 31 and the current collecting tabs 70 are respectively secured to the outer case 3 by, for example, an insulating guard 34. The insulating guard 34 is fixed to the electrode group 5 by an insulating tape 36. Here, the insulating guard 34 is disposed in contact with the inner wall of the outer case 3, so that the electrode Although this has the effect of suppressing vibration of the group 5, it is possible to The terminal insulator 35 may be provided between the external terminal 23 and the cover member 7. The terminal 23 and the cover member 7 are electrically insulated.

[0020] The metal member 16 used in the secondary battery 1 according to the first embodiment will be described with reference to FIG. FIG. 3 is a development view of the metal member 16 in the secondary battery 1 according to the first embodiment. As shown in FIG. 3, the metal member 16 has a first plate portion 40 and a second plate portion 42. The plate portion 40 abuts against at least a portion of one surface of the current collecting tab 70, and the second plate portion 42 The current collector tab 70 is in contact with at least a portion of the other surface of the current collector tab 70. When the electrode group 5 is used and current collecting tabs 70 are provided on both ends of the electrode group 5, the first plate portion The second plate portion 40 abuts against at least a part of the inner surface of the current collecting tab 70, and the second plate portion 42 abuts against at least a part of the inner surface of the current collecting tab 70, but the arrangement method is not limited thereto. Here, the first plate portion 40 and the second plate portion 42 are not necessarily fixed to the current collecting tab 70. The portion that comes into contact with the surface is called a contact portion 64. The first plate portion 40 and the second plate portion 42 are It is preferable that the current collectors are arranged facing each other via multiple layers of current collector tabs 70. The current collecting tab 70 is supported by the first plate portion 40 and the second plate portion 42. It is sufficient that the object is clamped.

[0021] Each of the first plate portion 40 and the second plate portion 42 is in contact with at least one surface of the current collecting tab 70. After being placed in the current collecting tab 70, the first plate portion 40 is welded to at least a portion of one surface of the current collecting tab 70. The second plate portion 42 is welded to at least a part of the other surface of the current collecting tab 70. This step is called a welding step. At least a part of the second plate portion 42 is welded to the lead 31. In the welding with the lead 31, the lead 31 is welded to the first plate portion 40 or the second plate portion 41 of the metal member 16. It is sufficient that the first plate portion 40 and the second plate portion 42 are welded to at least a part of the first plate portion 40 and the second plate portion 42. It may be welded with a person.

[0022] The electrode group 5 after the metal member 16 of this embodiment is welded to the current collecting tab 70 and the lead 31. The peripheral structure will be described with reference to Fig. 4. Fig. 4 shows the peripheral structure of the secondary battery 1 according to the first embodiment. 1 is a perspective view showing the periphery of the electrode group 5. FIG. The welding of the second plate portion 42 to the other surface of the current collecting tab 70 and the lead 31 is performed by, for example, For example, ultrasonic welding is used. The ultrasonic welding is performed by placing the metal on the anvil (not shown) of the ultrasonic welding machine. The lead 31, the second plate portion 42, the current collecting tab 70, and the first plate portion 40 are stacked in this order. Then, ultrasonic vibration is applied from above the first plate portion 40 using a horn (not shown) of an ultrasonic welding machine. As a result, the lead 31 is connected to the electrode group 5 via the metal member 16 and the current collecting tab 70. The welding method is not limited to ultrasonic welding, and the lead 31 is joined to the metal member 16 and the assembly. It may be joined to the electrode group 5 via the electrode tab 70.

[0023] The electrode group 5 after the metal member 16 of this embodiment is welded to the current collecting tab 70 and the lead 31. The peripheral structure will be described with reference to Figures 5 and 6. Figure 5 shows a secondary battery according to the first embodiment. 5 is a partial cross-sectional view in the Z direction taken along line II in FIG. 4, and schematically shows the periphery of a metal member. 6 is a cross-sectional view of the secondary battery according to the first embodiment taken along line II in FIG. 5 and 6 are cross-sectional views in the Z direction along the positive electrode 13 side and enlarged views of the metal members. However, it is preferable that the negative electrode 15 side has a similar structure.

[0024] After welding the metal member 16 and the current collecting tab 70, as shown in FIGS. 5 and 6, A weld 44 is formed on the plate portion 40. This is because, in this embodiment, the metal member 16 and The current collecting tab 70 is welded by ultrasonic welding, using a horn (not shown) of an ultrasonic welding machine. Since ultrasonic vibration is applied from the first plate portion 40 to the first plate portion 40, a welded portion 44 is formed on the first plate portion 40. The welded portion 44 between the metal member 16 and the current collecting tab 70 is formed by welding the first plate portion 40 or the second plate portion 40. It is sufficient that the first plate portion 40 and the second plate portion 42 are formed with the insulating film. The welded portion 44 may be formed on both the first plate portion 42 and the second plate portion 43. Although one or more electrodes may be formed on the surface of the substrate 40, it is preferable to form three electrodes from the viewpoint of welding strength. stomach.

[0025] As shown in FIG. 3, the first plate portion 40 and the second plate portion 42 of the metal member 16 are The first plate portion 40 and the second plate portion 4 2 is rectangular or approximately rectangular, the area where the current collecting tab 70 and the metal member 16 can come into contact with each other is large. In this region, the contact area between the current collecting tab 70 and the metal member 16 can be maximized. Since the first plate portion 40 and the second plate portion 42 of 16 are rectangular or substantially rectangular, The metal member 16 can stably hold the current collecting tab 70. By ensuring a sufficient contact area with the metal member 16, stable welding between the metal member 16 and the current collecting tab 70 can be achieved. Here, the rectangular shape may have four chamfered corners. The first plate portion 40 and the second plate portion 42 of the embodiment have two rectangular edges that are chamfered. With this shape, when the metal member 16 is placed on the current collecting tab 70, the corners of the metal member 16 The first plate portion 40 and the second plate portion 42 are It is preferable that the current collecting tab 70 is in a pair shape from the viewpoint of ease of clamping and stability. However, the present invention is not limited to these.

[0026] The metal member 16 has an integral structure in which the first plate portion 40 and the second plate portion 42 are joined together via a bent portion 50. By making the metal member 16 have such an integral structure, the current collector This makes it easy to clamp the current collecting tab 70 between the metal members 16. This reduces the time required for manufacturing the secondary battery 1, thereby improving the productivity.

[0027] As shown in FIG. 3, the first plate portion 40 and the second plate portion 42 each have two In this embodiment, the starting point 52 of the slit portion 60 is the first plate The slit portion 60 is disposed on the short side 90 of the first plate portion 40 and the second plate portion 42, and the slit portion 60 extends from the starting point 52 to the The first plate portion 40 and the second plate portion 42 are formed in a direction parallel or approximately parallel to the long sides 80 thereof. Here, the starting point 52 of the slit portion 60 is the slit when the current collecting tab 70 is clamped by the metal member 16. In the base portion 60, the first plate portion 40 and the second plate portion 50 are located farthest from the active material support portion. The position of the starting point 52 is not limited to this, and may be on the periphery of the first plate portion 40. It is sufficient that the second plate portion 42 is disposed on the peripheral edge thereof.

[0028] The start point 52 of the slit portion 60 is located at the welded portion 44 between the metal member 16 and the current collecting tab 70. The electrode is disposed closer to the active material support portion than the position farthest from the active material support portion. In the welded portion 44 between the metal member 16 and the current collecting tab 70, The position is the line R shown in Figures 5 and 6. The line R is the line between the metal member 16 and the current collecting tab 70. In the welded portion 44 with the first plate portion, a certain point is included which is the furthest from the active material support portion side, and The slits 60 are formed in a direction parallel to the long sides of the first plate 40 or the second plate 42. is disposed closer to the active material support portion than the line R, and as will be described later, the metal member 16 and the current collecting The first plate portion 40 or the second plate portion 40 in which the slit portion 60 is provided is welded to the tab 70. 42 is provided with a curved portion 62.

[0029] After the metal member 16 of this embodiment is welded to the current collecting tab 70 and the lead 31, the first plate The curved portion 62 provided on the first plate portion 40 or the second plate portion 42 will be described with reference to FIG. 7 is a view in the Z direction along line II-II in FIG. 4 of the secondary battery 1 according to the first embodiment. Although FIG. 7 shows the structure on the positive electrode 13 side, the negative electrode 15 side also has a similar structure. It is preferable that

[0030] As shown in FIGS. 4 and 7, after the metal member 16 and the current collecting tab 70 are welded together, the slit portion 6 The first plate portion 40 and the second plate portion 42 on which the 0 is provided are formed with a curved portion 62. This step is called a curved portion forming step. The curved portion 62 is formed by the metal member 16 and the current collecting tab 70. By welding, the portion adjacent to the slit portion 60 is curved, and the current collecting tab 70 After welding the metal member 16 and the current collecting tab 70, The part of the metal member 16 other than the curved part 62 is a contact part 64 with the current collecting tab 70, and the contact part 64 is welded. The contact portion 44 is also included. A metal member is provided at a position facing the curved portion 62 across the slit portion 60. After the contact portion 64 between the metal member 16 and the current collecting tab 70 is formed and the metal member 16 and the current collecting tab 70 are welded together, , a slit portion 60 is provided between a curved portion 62 and a contact portion 64. The slit portion 60 is provided after welding the metal member 16 and the current collecting tab 70. The metal member 16 is formed with a curved portion 62 so as to include the corner of the metal member 16 on the active material support portion side. The curved portion 62 and the adjacent portion are formed with a slit portion 60. Here, the slit portion 60 is located adjacent to the curved portion 62 in the height direction of the electrode group 5. Alternatively, the electrode group 5 may be curved in the lateral direction (the direction in which the current collecting tab 70 protrudes) of the electrode group 5. The contact portion 64 may be provided at a position adjacent to the metal member 16. and the current collecting tab 70 are in contact with each other. The entire portion of the portion 42 other than the curved portion 62 does not have to be a contact portion.

[0031] By providing the slit portion 60 and the curved portion 62 in the metal member 16, the metal member 16 The two corners on the active material support side do not contact the current collecting tab 70, and the curved portion 62 contacts the current collecting tab 70. As a result, for example, the metal member welded to the lead 31 may come into contact with the secondary battery 1 due to vibration. Even if the current collecting tab 70 swings relative to the metal member 16, the contact portion between the current collecting tab 70 and the metal member 16 is bent. Therefore, scratches and breakage due to rubbing of the current collecting tab 70 can be suppressed. This makes it possible to provide a secondary battery 1 in which an increase in internal resistance is suppressed.

[0032] In this embodiment, the starting point 52 of the slit portion 60 of the metal member 16 is located between the first plate portion 40 and the and on the short side 90 of the second plate portion 42 and at the welded portion 44, the portion furthest from the active material support portion side. The slit portion 60 is disposed on the active material support portion side of the position (line R) where the slit portion 60 is located. The grooves are formed in a direction parallel or approximately parallel to the long sides 80 of the plate portion 40 and the second plate portion 42 . By arranging the start point 52 of the slit portion 60 closer to the active material support portion than the line R, the start point 52 When the metal member 16 is disposed closer to the end of the current collecting tab 70 than when ... wire R is disposed closer to the end of the current collecting tab 70 When the first plate portion 40 and the second plate portion 42 are welded together, the first plate portion 40 and the second plate portion 42 are welded together. This makes it easier to separate from the electrical tab 70, and the curved portion 62 can be easily provided.

[0033] Modified examples of the slit portion 60 of the metal member 16 will be described with reference to FIGS. 8 to 10. 8 to 10 are diagrams showing the secondary battery according to the first embodiment along line II in FIG. 8 to 10 are partial cross-sectional views in the Z direction, each showing a schematic cross-sectional view of the metal member and its surroundings. Although the structure of the electrode 13 side is shown, it is preferable that the negative electrode 15 side has a similar structure. The starting point 52 of the slit portion 60 of the material 16 is located on the periphery of the first plate portion 40 and the second plate portion 42. and the welding portion 44 is arranged at a position (line R) farthest from the active material support portion side. The slit portion 60 of the metal member 16 shown in FIG. The starting point 52 of the slot portion 60 is disposed on the short side 90 of the first plate portion 40 and the second plate portion 42, The slit portion 60 extends from the starting point 52 parallel to the long sides 80 of the first plate portion 40 and the second plate portion 42. or formed in a direction other than approximately parallel.

[0034] In addition, the slit portion 60 of the metal member 16 shown in FIG. 9 has a start point 52 of the slit portion 60 at the first position. The slit portion 60 is disposed on the long side 80 of the first plate portion 40 and the second plate portion 42, and the slit portion 60 extends from the starting point 52 The first plate portion 40 and the second plate portion 42 are formed in a direction parallel or approximately parallel to the short sides 90 thereof. The positions where the slits 60 of the metal member 16 are formed are not limited to those shown in FIG. The end portion 60 extends from the starting point 52 parallel to or approximately parallel to the short sides 90 of the first plate portion 40 and the second plate portion 42. The slits 6 of the metal member 16 shown in FIG. 0 indicates that the starting point 52 of the slit portion 60 is located on the two corners of the first plate portion 40 and the second plate portion 42. will be placed in.

[0035] As shown in FIGS. 5 and 8 to 10, a slit portion 60 is provided in the metal member 16. When the metal member 16 and the current collecting tab 70 are welded together, the first plate having the slit portion 60 is welded to the metal member 16. The first plate portion 40 and the second plate portion 42 may be provided with a curved portion 62. In the slit portion 60 of the metal member 16 shown in FIG. 10, as shown in FIG. The start point 52 of the slit portion 60 is arranged on the first plate 90, and the slit portion 60 extends from the start point 52 to the first plate 90. It is preferable that the direction of the groove 44 is parallel or approximately parallel to the long sides 80 of the first plate portion 40 and the second plate portion 42. 5 is formed in the direction of the long side 80 of the metal member 16 as shown in FIG. The welding portion 44 is located on the side 72 of the welding portion 44 and is located on a straight line in the formation area of ​​the welding portion 44. Here, the side 72 of the welded portion 44 in the direction of the long side 80 of the metal member 16 is the line. 6. The line S is the welded portion between the metal member 16 and the current collecting tab 70. 44, including a certain point closest to the active material support portion side, and The metal member 16 shown in FIG. 5 is preferable for the following reasons. This is explained below.

[0036] For example, as in this embodiment, the welded portion 44 is formed on the metal member 16 from the viewpoint of welding strength. It is preferable that three of the electrodes are formed in the direction of the long side 80 of the member 16. In this case, for example, During vibration, the side 72 of the welded portion 44 in the direction of the long side 80 of the metal member 16 is Therefore, as shown in FIG. 5, the slit portion 60 vibrates together with the metal member 16. The welding portion 44 is located on the side 72 of the welding portion 44 in the direction of the long side 80 of the welding portion 44. The slit portion 60 is formed parallel or substantially parallel to the curved portion 62. When the secondary battery 1 is vibrated, the contact portion 64 facing the secondary battery 1 comes into contact with the welded portion 44 and the current collecting tab 70. As a result, the end of the contact portion 64 rubs against the current collecting tab 70, 70 can be prevented from breaking.

[0037] The slit portion 60 of the metal member 16 is provided in each of the first plate portion 40 and the second plate portion 42. It is preferable to provide two of them. This allows the two corners of the metal member 16 on the active material support side to be The first plate portion 40 and the second plate portion 62 are curved portions 62, and the curved portions 62 come into contact with the current collecting tabs 70. The two slits 60 provided on the first and second plate portions 40 and 42 are and the second plate portion 42 are provided symmetrically with respect to a line Q connecting the midpoints M of the long sides 80 of the first plate portion 42. This allows the curved portion 62 of the metal member 16 to be symmetrical with respect to the line Q. Therefore, the current collecting tab 70 is held stably. The slits 60 provided in each of the plate portions 42 are not limited to these, and may be formed in the first plate portion 4 It is sufficient that one or more plates are provided on at least one of the first plate portion 40 and the second plate portion 42. In addition, the first plate portion 40 or the second plate portion 42 of the metal member 16 is provided with The number of slit portions 60 may be different.

[0038] In this embodiment, the first plate portion 40 is welded to the inner surface of the current collecting tab 70, and the second plate portion 42 is preferably welded to the outer surface of the current collecting tab 70, and the first plate portion 40 and the second plate portion By providing the slits 60 on each of the plate portions 42, the inner surface of the current collecting tab 70 and This can prevent breakage of both outer surfaces.

[0039] The length A from the start point 52 of the slit portion 60 of the metal member 16 and the length A of the first plate portion 40 or the second plate portion 40 It is preferable that the length B of the long side 80 of the plate portion 42 satisfies the relationship 0.05≦A / B≦0.2. Here, the length A of the slit portion 60 from the starting point 52 is, as shown in FIG. the longest length in a direction parallel to the long side 80 of the first plate portion 40 or the second plate portion 42; The length A from the start point 52 of the slit portion 60 and the length A of the first plate portion 40 or the second plate portion 42 When the relationship (A / B) between the length B of the long side 80 and the length B of the long side 80 is 0.05 or more, the slit portion 60 This makes the metal member 16 more likely to deform, and the metal member 16 and the current collecting tab 70 are easily bent during welding. The length A of the slit portion 60 from the starting point 52 and the distance to the first plate portion 40 are also When the relationship (A / B) between the length B of the long side 80 of the second plate portion 42 and the long side 80 of the second plate portion 42 is 0.2 or less, When the start point 52 of the slit portion 60 is located on the short side 90 of the metal member 16 as shown in FIG. In this case, the slit portion 60 can be provided so as to avoid the welded portion 44 between the metal member 16 and the current collecting tab 70. As a result, the strength of the metal member 16 can be maintained. When the start point 52 of the slit portion 60 is located on the long side, the metal member 16 and the current collecting tab 70 When the welding is performed, the curved portion 62 and the contact portion 64 formed on the metal member 16 are separated. can be suppressed.

[0040] In the first embodiment, the metal member 16 is provided with a slit portion 60, and the slit portion 6 The starting point 52 of the welding point 0 is disposed on the short side 90 of the first plate portion 40 and the second plate portion 42. In the portion 44, the active material support portion is located closer to the active material support portion than the position (line R) that is farthest from the active material support portion. The slit portion 60 is placed between the first plate portion 40 and the second plate portion 42 from the starting point 52. The metal member 16 is formed in a direction parallel or substantially parallel to the long side 80 of the metal member 16. Therefore, when the metal member 16 and the current collecting tab 70 are welded together, the active material carrying portion of the metal member 16 is The two corners are provided with curved portions 62, which come into contact with the current collecting tabs 70. As a result, when the secondary battery 1 is vibrated, for example, the corners of the metal member 16 are prevented from rubbing against the current collecting tab 70. Breakage of the current collecting tab 70 due to the above-mentioned stress can be suppressed. Therefore, it is possible to provide a secondary battery 1 in which an increase in internal resistance is suppressed. The secondary battery 1 can suppress, for example, deterioration of current characteristics and low-temperature characteristics, and capacity degradation.

[0041] In addition, as a means for increasing the capacity of the secondary battery, the weight of the electrode group 5 is increased, and the secondary battery 1 Even if damage due to friction between the corners of the metal member 16 and the current collecting tab 70 during vibration increases, Therefore, the breakage of the current collecting tab 70 due to the corners of the metal member 16 rubbing against the current collecting tab 70 is suppressed. Therefore, by using the secondary battery 1 of this embodiment, it is possible to provide the electrode group By increasing the weight of 5, it becomes possible to increase the capacity and size of the secondary battery.

[0042] (Second embodiment) A secondary battery module 100 according to a second embodiment will be described with reference to FIG. 1 is a perspective view schematically showing a secondary battery module 100 according to a second embodiment; The secondary battery module 100 includes a plurality of secondary batteries 1 according to the first embodiment. The secondary battery 1 is electrically connected to the connecting member 102 such as a bus bar. The connection is not limited to series, but can also be parallel. Alternatively, the secondary battery 1 may be connected to a secondary battery different from the secondary battery 1.

[0043] In the second embodiment, since the secondary battery 1 of the first embodiment is connected, for example, When the battery module 100 vibrates, the corners of the metal members 16 inside the secondary batteries 1 come into contact with the current collecting tabs 7. 0, the breakage of the current collecting tab 70 due to friction with the A secondary battery module including a secondary battery 1 in which an increase in internal resistance is suppressed by suppressing A secondary battery module 100 can be provided, which includes a secondary battery 1 in which an increase in internal resistance is suppressed. For example, the module 100 can suppress deterioration of current characteristics and low-temperature characteristics, as well as capacity degradation.

[0044] In addition, as a means for increasing the capacity of the secondary battery, the weight of the electrode group 5 is increased, and the secondary battery 1 Even if damage due to friction between the corners of the metal member 16 and the current collecting tab 70 during vibration increases, Therefore, the breakage of the current collecting tab 70 due to the corners of the metal member 16 rubbing against the current collecting tab 70 is suppressed. It is possible to provide a secondary battery module 100 including the secondary battery 1. By using the secondary battery 1, the weight of the electrode group 5 can be increased, thereby enabling a high capacity or large-sized secondary battery. It is possible to provide a secondary battery module equipped with a battery.

[0045] According to at least one of the embodiments of the secondary battery 1 described above, the metal member 16 has a groove. The slit portion 60 is provided, and the start point 52 of the slit portion 60 is located between the first plate portion 40 and the second plate portion 4 2 and at the position ( The metal member 16 is disposed on the active material support portion side of the line R. When the member 16 and the current collecting tab 70 are welded, the two corners of the metal member 16 on the active material carrying portion side are Since the curved portion 62 is provided, the curved portion 62 comes into contact with the current collecting tab 70. For example, when the secondary battery 1 is vibrated, the corners of the metal member 16 rub against the current collecting tab 70, causing damage to the current collecting tab. Furthermore, by suppressing the breakage of the current collecting tab 70, the internal resistance can be reduced. It is possible to provide a secondary battery 1 in which the increase in internal resistance is suppressed. For example, deterioration of current characteristics and low-temperature characteristics, and capacity degradation can be suppressed.

[0046] In addition, even when the weight of the electrode group 5 is increased as a means for increasing the capacity of the secondary battery, When the secondary battery module 100 is vibrated, the end of the metal member 16 collects current inside the secondary battery 1. Breakage of the current collecting tab 70 due to friction with the tab 70 can be suppressed, and an increase in internal resistance can be suppressed. It is possible to provide a secondary battery module 100 including the secondary battery 1. By using the secondary battery 1, the weight of the electrode group 5 can be increased, thereby enabling a high capacity or large-sized secondary battery. It is possible to provide a secondary battery module equipped with a battery.

[0047] Although several embodiments of the present invention have been described, these embodiments are presented by way of example only. These embodiments are not intended to limit the scope of the invention. It is possible to implement the invention in various forms, and various omissions, modifications, and additions may be made without departing from the spirit of the invention. These embodiments and their modifications are within the scope and spirit of the invention. The inventions described in the claims and their equivalents are also included in the scope of the invention. be. [Explanation of symbols]

[0048] 1... secondary battery, 3... outer case, 5... electrode group, 7... cover member, 9... outer case opening, 13 ...positive electrode, 13a...positive electrode current collector, 15...negative electrode, 15a...negative electrode current collector, 16...metal member, 16 a...positive electrode metal member, 16b...negative electrode metal member, 17...pouring port, 19...sealing plate, 21...gas exhaust Outlet valve, 23... external terminal, 23a... positive electrode external terminal, 23b... negative electrode external terminal, 29... insulating gas Socket, 31...lead, 31a...positive electrode lead, 31b...negative electrode lead, 33...internal insulating member , 34...insulating guard, 35...terminal insulator, 36...insulating tape, 40...first plate portion, 42... Second plate portion, 44... welded portion, 50... bent portion, 52... starting point, 60... slit portion, 62... curve portion, 64...contact portion, 70...current collecting tab, 70a...positive electrode current collecting tab, 70b...negative electrode current collecting tab, 2...side, 80...long side, 90...short side, 100...secondary battery module, 102...connecting member.

Claims

1. The active material support portion includes an active material supported on a metal foil, and is sandwiched between metal members at at least one end. an electrode group having multiple layers of current collecting tabs supported thereon; a lead welded to at least a portion of the metal member; the metal member includes a first plate portion welded to at least a portion of one surface of the current collecting tab; a second plate portion welded to at least a portion of the other surface of the current collecting tab, At least one of the first plate portion and the second plate portion is a contact portion in contact with the current collecting tab; one or more curved portions formed in a direction away from the current collecting tab; a slit portion provided between the contact portion and the curved portion.

2. The first plate portion or the second plate portion has at least one or more welded portions to the current collecting tabs. having a weld, The slit portion is formed on the periphery of at least one of the first plate portion and the second plate portion. It has a starting point on the edge, The starting point of the slit portion is located at the position farthest from the active material support portion in the welded portion. The secondary battery according to claim 1 , wherein the electrode is disposed closer to the active material support portion than the electrode.

3. The metal member has an integral structure in which the first plate portion and the second plate portion are bent via a bent portion. The secondary battery according to claim 1 .

4. the electrode group is a wound body, one of the current collecting tabs is sandwiched between at least two of the metal members, One of the first plate portion and the second plate portion is welded to the inner surface of the current collecting tab, 2. The method of claim 1, wherein the other of the first plate portion and the second plate portion is welded to the outer surface of the current collecting tab. The secondary battery according to claim 1.

5. At least one of the first plate portion and the second plate portion has a long side and a short side. It is a rectangular shape, The length A of the slit portion from the starting point and the length of the first plate portion or the second plate portion The length B of the side satisfies the relationship of the following formula (1): Secondary battery. 0.05≦A / B≦0.2 (1)

6. The starting point of the slit portion is disposed on the short side of the first plate portion or the second plate portion. And, The slit portion extends from the starting point parallel to the long side of the first plate portion or the second plate portion. The secondary battery according to claim 5 , wherein the electrodes are formed in a uniform direction.

7. At least one of the first plate portion and the second plate portion has two of the slits. It has a department, The start point of one of the slit portions and the start point of the other of the slit portions are located on the opposite sides of the longitudinal The secondary battery according to claim 5 , wherein the electrodes are arranged symmetrically with respect to a line connecting the midpoints of the sides.

8. The secondary battery according to claim 1; an external terminal provided on the secondary battery; A secondary battery module including a connection member electrically connected to the external terminal.

9. a housing step of housing the electrode group in an exterior case; At least one of the plurality of layers of current collecting tabs provided on the electrode group a welding step of welding a metal member to at least a part of one surface; A curved portion is formed in at least a part of the metal member by the welding process. A method for manufacturing a secondary battery, comprising the steps of:

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