JP2016143618A - Rectangular secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rectangular secondary battery capable of improving rigidity of a collector plate.SOLUTION: A rectangular secondary battery 100 of the present invention includes collector plates 44, 24 connected to an electrode of a wound group at the inside of a battery container to support the wound group. The collector plates 44, 24 comprise a clad material obtained by the clad bonding of base materials 45, 25 and members 46, 26 having a higher Young's modulus than the base materials 45, 25, respectively.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a secondary battery in which a winding group is housed in a battery can and power is taken out from the winding group through a current collecting plate, and more specifically, a prismatic battery with an improved structure of the current collecting plate. Next battery.

  In recent years, cylindrical and prismatic secondary batteries, which are batteries with high energy density, have been developed as power sources for electric vehicles and the like. Among these, there is (Patent Document 1) as a technique that is widely used in prismatic secondary batteries. In this publication, “a nonaqueous electrolyte secondary battery capable of suppressing the corrosion of the terminal portion and maintaining the connection state between each terminal portion and the electrode group over a long period of time and improving the yield and The object is to provide a manufacturing method thereof ”(see abstract). The current collector plate and the terminal were made of an integral single metal.

JP 2011-204405 A

  In the square secondary battery, there is a demand for a large capacity, and the weight of the wound group has increased. However, since the current collector plate is made of copper or aluminum, it has excellent electrical conductivity, but lack of rigidity has become a problem.

  This invention is made | formed in view of said point, The place made into the objective is to provide the square secondary battery which can improve the rigidity of a current collecting plate.

  The prismatic secondary battery of the present invention that solves the above-described problem is a winding group in which an electrode is wound, a battery container that houses the winding group, and an electrode of the winding group that is connected in the battery container. A prismatic secondary battery having a current collector for supporting the wound group, wherein the current collector is made of a clad material obtained by clad joining a base material and a member having a higher Young's modulus than the base material. It is characterized by being composed.

  According to the present invention, the rigidity of the current collector plate can be improved. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

The external appearance perspective view of a square secondary battery. The disassembled perspective view of the square secondary battery shown in FIG. The exploded perspective view of a winding group. 2 is a conceptual diagram of an exploded perspective view of a lid assembly in Embodiment 1. FIG. The conceptual diagram of the crimping | crimped part cross section of the cover assembly in Example 1. FIG. The conceptual diagram explaining the structure of the current collection board in Example 1. FIG. The conceptual diagram explaining the structure of the current collection board in Example 2. FIG. The conceptual diagram explaining the structure of the current collection board in Example 3. FIG. The conceptual diagram explaining the structure of the current collecting plate in Example 4. FIG.

  Embodiments to which the present invention is applied will be described below with reference to the drawings. In each of the following embodiments, a case where the square secondary battery is a lithium ion secondary battery will be described as an example. However, the present invention is not limited to the lithium ion secondary battery, and can be applied to other batteries.

[Example 1]
FIG. 1 is an external perspective view of a prismatic secondary battery, and FIG. 2 is an exploded perspective view of the prismatic secondary battery.
The prismatic secondary battery 100 is a flat wound battery having a flat wound group 3, and includes a battery container that accommodates the wound group 3. The battery container includes a bottomed rectangular battery can 1 and a battery lid 6 that closes an opening 1 a that opens at the top of the battery can 1. The battery can 1 has a pair of opposed wide side surfaces 1b having a relatively large area, a pair of opposed narrow side surfaces 1c having a relatively small area, and a rectangular bottom surface 1d. An opening 1a opened upward is formed.

  A wound group 3 is accommodated in the battery can 1, and an opening 1 a of the battery can 1 is sealed by a battery lid 6. The battery lid 6 has a substantially rectangular flat plate shape, and is welded so as to close the upper opening 1 a of the battery can 1 to seal the battery can 1. The battery lid 6 is provided with a positive external terminal 14 and a negative external terminal 12. The wound group 3 is charged through the positive external terminal 14 and the negative external terminal 12, and power is supplied to the external load. The battery cover 6 is integrally provided with a gas discharge valve 10, and when the pressure in the battery container rises, the gas discharge valve 10 opens to discharge gas from the inside, and the pressure in the battery container is reduced. Thereby, the safety of the prismatic secondary battery 100 is ensured.

  The wound group 3 is accommodated in the battery can 1 while being covered with the insulating protective film 2. Since the wound group 3 is wound in a flat shape, the wound group 3 has a pair of curved surface portions facing each other and having a semicircular cross section, and a flat surface portion formed continuously between the pair of curved surface portions. ing. The winding group 3 is inserted into the battery can 1 from one curved surface portion side so that the winding axis direction is along the lateral width direction of the battery can 1, and the other curved surface portion side is an opening that is the upper portion of the battery can 1. It is arranged on the 1a side.

  The positive electrode metal foil exposed portion 34 b of the winding group 3 is joined to the positive electrode current collector plate 44 and is electrically connected to the positive electrode external terminal 14 provided on the battery lid 6 via the positive electrode current collector plate 44. Yes. The negative electrode metal foil exposed portion 32 b of the wound group 3 is joined to the negative electrode current collector plate 24 and is electrically connected to the negative electrode external terminal 12 provided on the battery lid 6 via the negative electrode current collector plate 24. Has been. Thereby, electric power is supplied from the winding group 3 to the external load via the positive electrode current collecting plate 44 and the negative electrode current collecting plate 24, and externally supplied to the wound group 3 via the positive electrode current collecting plate 44 and the negative electrode current collecting plate 24. The generated power is supplied and charged.

  In order to electrically insulate the positive electrode current collector plate 44 and the negative electrode current collector plate 24, and the positive electrode external terminal 14 and the negative electrode external terminal 12 from the battery lid 6, a gasket 5 and an insulating plate 7 are provided on the battery lid 6. It has been. Moreover, after injecting electrolyte solution into the battery can 1 from the liquid injection port 9, a liquid injection stopper 11 is joined to the battery lid 6 by laser welding to seal the liquid injection port 9, and the rectangular secondary battery 100 is sealed. To do.

  Here, examples of a material for forming the positive electrode external terminal 14 and the positive electrode current collector plate 44 include aluminum and an aluminum alloy, and examples of a material for forming the negative electrode external terminal 12 and the negative electrode current collector plate 24 include copper and a copper alloy. Can be mentioned. Examples of the material for forming the insulating plate 7 and the gasket 5 include resin materials having insulating properties such as polybutylene terephthalate, polyphenylene sulfide, and perfluoroalkoxy fluororesin.

In addition, the battery lid 6 is provided with a liquid injection port 9 for injecting an electrolytic solution into the battery container. The liquid injection port 9 is provided with an injection plug 11 after the electrolytic solution is injected into the battery container. Is sealed. Here, as the electrolytic solution injected into the battery container, for example, a non-aqueous electrolytic solution in which a lithium salt such as lithium hexafluorophosphate (LiPF ₆ ) is dissolved in a carbonic acid ester-based organic solvent such as ethylene carbonate is used. Can be applied.

  The positive external terminal 14 and the negative external terminal 12 have a weld joint that is welded to a bus bar or the like. The weld joint has a rectangular parallelepiped block shape protruding upward from the battery lid 6, and has a configuration in which the lower surface faces the surface of the battery lid 6 and the upper surface is parallel to the battery lid 6 at a predetermined height position. Have. The positive electrode external terminal 14 is integrally formed with a positive electrode connection portion 14 a that is electrically connected to the positive electrode current collector plate 44. The negative electrode external terminal 12 is electrically connected to the negative electrode current collector plate 24. A negative electrode connection portion 12a to be connected is integrally formed.

  The positive electrode connecting portion 14 a and the negative electrode connecting portion 12 a have a cylindrical shape that protrudes from the lower surfaces of the positive electrode external terminal 14 and the negative electrode external terminal 12 and can be inserted into the positive electrode side through hole 47 and the negative electrode side through hole 27 of the battery lid 6. Have. The positive electrode connecting portion 14a and the negative electrode connecting portion 12a penetrate the battery lid 6 and protrude to the inner side of the battery can 1 from the base portions 44a and 24a of the positive electrode current collector plate 44 and the negative electrode current collector plate 24, respectively. The positive electrode external terminal 14 and the negative electrode external terminal 12, and the positive electrode current collector plate 44 and the negative electrode current collector plate 24 are integrally fixed to the battery lid 6. The caulking portions of the positive electrode connecting portion 14a and the negative electrode connecting portion 12a are welded to the base portions 44a and 24a of the positive electrode current collector plate 44 and the negative electrode current collector plate 24, respectively, to ensure conductivity and improve the fixing strength. ing. A gasket 5 is interposed between the positive electrode external terminal 14 and the negative electrode external terminal 12 and the battery lid 6, and an insulating plate is interposed between the positive electrode current collector plate 44 and the negative electrode current collector plate 24 and the battery lid 6. 7 is interposed.

  The positive electrode current collector plate 44 and the negative electrode current collector plate 24 are bent at respective rectangular plate-like base portions 44 a and 24 a disposed to face the back surface of the battery lid 6, and at the side ends of the respective base portions 44 a and 24 a. And extending toward the bottom surface 1d along the wide side surface 1b of the battery can 1 and connected in a state of being superimposed facing the positive electrode metal foil exposed portion 34b and the negative electrode metal foil exposed portion 32b of the wound group 3. A welded portion 44b and a welded portion 24b. Opening holes 44c and 24c through which the positive electrode connecting portion 14a and the negative electrode connecting portion 12a are inserted are formed in the respective base portions 44a and 24a.

  An insulating protective film 2 is wound around the wound group 3. The insulating protective film 2 is wound around the winding group 3 with the direction along the flat surface of the winding group 3 and the direction orthogonal to the winding axis direction of the winding group 3 as the central axis direction. The insulating protective film 2 is made of a single sheet or a plurality of film members made of synthetic resin such as PP (polypropylene), for example, and is a direction parallel to the flat surface of the wound group 3 and perpendicular to the winding axis direction. Is wound around at least one turn, so that the whole can be covered completely.

FIG. 3 is an exploded perspective view showing a state in which a part of the wound group is developed.
The winding group 3 is configured by winding the negative electrode 32 and the positive electrode 34 in a flat shape with separators 33 and 35 interposed therebetween. The separators 33 and 35 have a role of insulating between the positive electrode 34 and the negative electrode 32. In the winding group 3, the outermost electrode is the negative electrode 32, and separators 33 and 35 are wound further outside.

  The positive electrode 34 has a positive electrode metal foil made of aluminum or an aluminum alloy, and a positive electrode mixture layer 34a formed by coating a positive electrode mixture containing a positive electrode active material on both surfaces of the positive electrode metal foil. A positive electrode metal foil exposed portion 34b where no positive electrode mixture is applied is provided at one end in the width direction of the metal foil.

The negative electrode 32 has a negative electrode metal foil made of copper or a copper alloy, and a negative electrode mixture layer 32a formed by coating a negative electrode mixture containing a negative electrode active material on both surfaces of the negative electrode metal foil. A negative electrode metal foil exposed portion 32b that is not coated with a negative electrode mixture is provided at the other end in the width direction of the metal foil.
The positive electrode metal foil exposed portion 34b and the negative electrode metal foil exposed portion 32b are regions where the metal surfaces of the positive electrode metal foil and the negative electrode metal foil are exposed, and the winding group 3 is positioned on one side and the other side in the winding axis direction. The positive electrode metal foil exposed part 34b and the negative electrode metal foil exposed part 32b are wound so as to be arranged separately.

  The portion where the negative electrode mixture layer 32a of the negative electrode 32 is applied is larger in the width direction than the portion of the positive electrode 34 where the positive electrode mixture layer 34a is applied, and the portion where the positive electrode mixture layer 34a is applied is always The negative electrode mixture layer 32a is overlaid so as to be sandwiched between the coated portions. The positive metal foil exposed portion 34b and the negative metal foil exposed portion 32b are bundled at a flat surface portion and joined to the welded portions 44b and 24b of the current collector plates 44 and 24 by welding. The separators 33 and 35 are wider than the portion where the negative electrode mixture layer 32a is applied in the width direction, but at positions where the metal foil surface at the end is exposed at the positive electrode metal foil exposed portion 34b and the negative electrode metal foil exposed portion 32b. Because it is wound, it does not hinder bundled welding.

  Regarding the negative electrode 32, 10 parts by weight of polyvinylidene fluoride (hereinafter referred to as PVDF) is added as a binder to 100 parts by weight of amorphous carbon powder as a negative electrode active material, and N as a dispersion solvent. -A negative electrode mixture in which methylpyrrolidone (hereinafter referred to as NMP) was added and kneaded was prepared. This negative electrode mixture was applied to both surfaces of a negative electrode metal foil having a thickness of 10 μm, leaving a negative electrode uncoated portion to be a welded portion. Then, the negative electrode 32 whose thickness of the negative electrode active material application part which does not contain a negative electrode metal foil is 70 micrometers was obtained through the drying, the press, and the cutting process.

In this embodiment, the case where amorphous carbon is used as the negative electrode active material is exemplified, but the present invention is not limited to this. Natural graphite capable of inserting and removing lithium ions and various artificial graphite materials , Carbonaceous materials such as coke, compounds such as Si and Sn (for example, SiO, TiSi ₂ etc.), or composite materials thereof may be used. It is not limited.

Regarding the positive electrode 34, 10 parts by weight of flaky graphite as a conductive material and 10 parts by weight of PVDF as a binder are added to 100 parts by weight of lithium manganate (chemical formula LiMn ₂ O ₄ ) as a positive electrode active material. A positive electrode mixture was prepared by adding and kneading NMP as a dispersion solvent. This positive electrode mixture was applied on both surfaces of a positive electrode metal foil having a thickness of 20 μm, leaving a positive electrode uncoated portion to be a welded portion. Then, the positive electrode 34 with a positive electrode active material application part thickness of 90 μm not including the positive electrode metal foil was obtained through drying, pressing, and cutting processes.

  Further, in this example, the case where lithium manganate is used as the positive electrode active material is exemplified, but other lithium manganate having a spinel crystal structure or a lithium manganese composite oxide or layered in which a part is substituted or doped with a metal element A lithium cobalt oxide or lithium titanate having a crystal structure, or a lithium-metal composite oxide obtained by substituting or doping a part thereof with a metal element may be used.

  Further, in this example, the case where PVDF is used as the binder of the coating portion in the positive electrode and the negative electrode is exemplified, but polytetrafluoroethylene (PTFE), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene Use polymers such as butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride, chloroprene fluoride, acrylic resins, and mixtures thereof. Can do. Moreover, as a shaft core, what was comprised by winding the resin sheet whose bending rigidity is higher than any of positive electrode metal foil, negative electrode metal foil, and separators 33 and 35 can be used, for example. The wound group 3 may have a structure that does not have an axis.

  FIG. 4 is a conceptual diagram of an exploded perspective view of the lid assembly according to the first embodiment, and FIG. 5 is a conceptual diagram of a caulking section of the lid assembly according to the first embodiment. FIG. 6 is a conceptual diagram illustrating the configuration of the positive electrode current collector plate in Example 1. In FIG. 6, (a) is a perspective view schematically showing the positive electrode current collector plate, and (b) is a diagram of (a). b direction arrow view, (c) is a c direction arrow view of (a), (d) is a d direction arrow view of (a).

  As shown in FIG. 4, the lid assembly includes a battery lid 6, a positive electrode external terminal 14 and a negative electrode external terminal 12 provided on the battery lid 6, and a positive electrode that is caulked and fixed integrally to the battery lid 6 by the positive electrode external terminal 14. It has a current collector plate 44 and a negative electrode current collector plate 24 that is integrally caulked and fixed to the battery lid 6 by the negative electrode external terminal 12. The positive electrode metal foil exposed portion 34b and the negative electrode metal foil exposed portion 32b of the winding group 3 are bundled in the thickness direction of the winding group 3 on a flat surface portion, and a welded portion between the positive electrode current collector plate 44 and the negative electrode current collector plate 24. 44b and 24b are welded together. As a welding joining method, for example, ultrasonic welding, laser welding, resistance welding, or the like is used.

  The positive electrode current collector plate 44 and the negative electrode current collector plate 24 are made of a clad material in which base materials 45 and 25 and members 46 and 26 made of a metal material having a higher Young's modulus than the base materials 45 and 25 are clad. ing. Therefore, the rigidity of the positive electrode current collector plate 44 and the negative electrode current collector plate 24 can be improved as compared with a conventional structure composed of only the base material. Therefore, it is possible to support a wound group having a large weight. For example, when the rectangular secondary battery 100 is used in a PHEV (plug-in hybrid vehicle) or an EV (electric vehicle), the resistance to vibrations and impacts is improved. The effect of increasing is obtained.

  In the positive electrode current collector plate 44, a base material 45 is disposed on a surface facing the winding group 3, and a member 46 is disposed on a surface facing the battery lid 6 and the battery can 1. The base material 45 of the welded portion 44 b is welded to the positive electrode metal foil exposed portion 34 b of the wound group 3. The base material 45 of the positive electrode current collector plate 44 is continuously disposed between the base portion 44a and the welded portion 44b, and the member 46 of the positive electrode current collector plate 44 includes at least a part of the base portion 44a and the welded portion. 44b is continuously arranged between at least a part of 44b. In the present embodiment, the base material 45 is continuously disposed over the entire surface of the base portion 44a facing the winding group 3 and the entire surface of the welding portion 44b facing the winding group 3. The member 46 is continuously arranged over the entire surface of the base portion 44a facing the battery lid 6 and the entire surface of the welding portion 44b facing the wide side surface 1b in the battery can 1.

  Since the member 46 is disposed continuously between the base portion 44a and the welded portion 44b, the base portion 44a and the welded portion 44b, which are places where the greatest force acts in the positive electrode current collector plate 44, are formed. The boundary portion can be reinforced. Therefore, the support rigidity for supporting the wound group 3 by the positive electrode current collector plate 44 can be improved, and the swing and vibration of the wound group 3 in the battery container can be effectively prevented.

  In the negative electrode current collector plate 24, the base material 25 is disposed over the entire surface facing the winding group 3, and the member 26 is disposed over the entire surface facing the battery lid 6 and the battery can 1. . The base material 25 of the welded portion 24b is welded to the negative electrode metal foil exposed portion 32b of the wound group 3. The base material 25 of the negative electrode current collector plate 24 is continuously disposed between the base portion 24a and the welded portion 24b, and the member 26 of the negative electrode current collector plate 24 includes at least a part of the base portion 24a and the welded portion. 24b is continuously arranged between at least a part of 24b. In this embodiment, the base material 25 is continuously arranged over the entire surface of the base portion 24a facing the winding group 3 and the entire surface of the welding portion 24b facing the winding group 3. The member 26 is continuously disposed over the entire surface of the base 24a facing the battery lid 6 and the entire surface of the welded portion 24b facing the wide side surface 1b in the battery can 1.

  Since the member 26 is disposed continuously between the base 24a and the welded portion 24b, the base 24a and the welded portion 24b, which are locations where the greatest force acts in the negative electrode current collector plate 24, are provided. The boundary portion can be reinforced. Therefore, the support rigidity for supporting the wound group 3 by the negative electrode current collector plate 24 can be improved, and the swing and vibration of the wound group 3 in the battery container can be effectively prevented.

  The base material 45 of the positive electrode current collector plate 44 is made of aluminum or aluminum alloy, which is the same metal material as the positive electrode metal foil. The member 46 is made of a metal material having a higher Young's modulus than aluminum or aluminum alloy. Stainless steel is used. The base material 25 of the negative electrode current collector plate 24 is made of copper or a copper alloy, which is the same metal material as the negative electrode metal foil. The member 26 is a metal having a higher Young's modulus than copper or a copper alloy. Stainless steel is used as the material. Therefore, the welding of the positive electrode current collector plate 44 and the positive electrode metal foil exposed portion 34b of the wound group 3 and the welding of the negative electrode current collector plate 24 and the negative electrode metal foil exposed portion 32b of the wound group 3 are of the same type. It becomes welding of metal materials, joining by the conventional welding method is possible, and it can weld easily.

  The positive external terminal 14 is welded and joined to the positive current collector plate 44 at the caulked portion of the positive electrode connecting portion 14a, and the negative external terminal 12 is welded to the negative electrode current collecting plate 24 at the caulked portion of the negative electrode connecting portion 12a. Has been. Aluminum or aluminum alloy, which is the same kind of metal material as the base material 45 of the positive electrode current collector plate 44, is used for the positive electrode external terminal 14, and the same kind as the base material 25 of the negative electrode current collector plate 24 is used for the negative electrode external terminal 12. Copper or copper alloy, which is a metal material, is used. Therefore, welding of the caulking portion of the positive electrode connecting portion 14a of the positive electrode external terminal 14 and the positive electrode current collector plate 44 and welding of the caulking portion of the negative electrode connecting portion 12a of the negative electrode external terminal 12 and the negative electrode current collector plate 24 are also respectively performed. It becomes welding of the same kind of metal materials, joining by the conventional welding method is possible, and it can weld easily.

Table 1 shows the Young's modulus for each material ratio of aluminum and other metals. As shown in Table 1, a metal material having a higher Young's modulus than aluminum, such as stainless steel, titanium, chromium, molybdenum, tungsten, vanadium, tantalum, or niobium, is used as a member, and aluminum is used as a base material 45 to form a clad material. Thus, it can have higher rigidity than that of the positive electrode current collector plate made of only aluminum or aluminum alloy.

Table 2 shows the Young's modulus of the aluminum alloy. In the present embodiment, the clad material can be configured using an aluminum alloy as a base material instead of aluminum (pure aluminum).

  When the positive electrode current collector plate is made of a clad material that uses aluminum or an aluminum alloy as a base material and a metal material that is less expensive than aluminum or an aluminum alloy as a member, it is less expensive than a positive electrode current collector plate made of only aluminum or an aluminum alloy. A current collector plate is obtained. Therefore, the material cost can be kept low, and the prismatic secondary battery 100 can be provided at low cost.

  When the positive electrode current collector plate is made of a clad material using aluminum or an aluminum alloy as a base material and a metal material lighter than aluminum or an aluminum alloy as a member, it is lighter than a positive electrode current collector plate made of only aluminum or an aluminum alloy. A current collector plate is obtained. Accordingly, the overall weight of the square secondary battery 100 can be reduced.

This embodiment can also be applied to the negative electrode current collector plate 24. Table 3 shows the Young's modulus for each material ratio of copper and other metals. As shown in Table 3, the negative electrode current collector plate 24 joined with a metal having a higher Young's modulus than copper, such as stainless steel, titanium, chromium, molybdenum, tungsten, vanadium, and tantalum, is made of only copper or copper alloy. It can have higher rigidity than that of the electric plate.

Table 4 shows the Young's modulus of the copper alloy. In the present embodiment, the clad material can be configured using a copper alloy as a base material instead of copper (pure copper).

  When the negative electrode current collector plate 24 is made of a clad material having copper or a copper alloy as a base material 25 and a metal material less expensive than copper or a copper alloy as a member 26, the positive electrode current collector plate made only of copper or a copper alloy is used. However, an inexpensive current collector plate can be obtained. Therefore, the material cost can be kept low, and the prismatic secondary battery 100 can be provided at low cost. When the negative electrode current collector plate is made of a clad material using copper or a copper alloy as a base material and a metal material lighter than copper or a copper alloy as a member, it is lighter than a positive electrode current collector plate made only of copper or a copper alloy. A current collector plate is obtained. Accordingly, the overall weight of the square secondary battery 100 can be reduced.

  As a manufacturing method of the positive electrode current collector plate 44 and the negative electrode current collector plate 24, for example, a clad material obtained by clad bonding the base materials 45 and 25 and the members 46 and 26 is cut out in a substantially L shape by a press machine. And it can manufacture by bending at a right angle so that the base material 45 may become inner side in the boundary part of the base parts 44a and 24a and the welding parts 44b and 24b.

  In this embodiment, the case where both the positive electrode current collector plate 44 and the negative electrode current collector plate 24 are made of a clad material is described as an example. However, only the positive electrode current collector plate 44 or only the negative electrode current collector plate 24 is described. May be made of a clad material. For example, when compared with a conventional product using aluminum for the positive electrode current collector plate and copper for the negative electrode current collector plate, if only the positive electrode current collector plate 44 is made of a clad material, aluminum is more preferable than copper. Since it is soft, the overall rigidity of the positive electrode current collector plate 44 and the negative electrode current collector plate 24 can be raised. In addition, when only the negative electrode current collector plate 24 is made of a clad material, the surface for forming a passive oxide film on the surface such as SUS, Ti group, V group, and Cr group shown in Table 3 is more electrically than copper. When a chemically stable member is used, there is an advantage that the surface area of copper in the member related to the elution of copper that leads to battery failure at the time of overdischarge is reduced.

  In this embodiment, the case where aluminum or an aluminum alloy is used for the base material 45 of the positive electrode current collector plate 44 and a metal material other than aluminum or aluminum alloy such as stainless steel is used for the member 46 has been described. Any material may be used as long as the Young's modulus is higher than that of the base material 45. For example, aluminum may be used for the base material 45, and an aluminum alloy having a Young's modulus higher than aluminum may be used for the member 46. The same applies to the negative electrode current collector plate 24. Copper may be used for the base material 25, and a copper alloy having a higher Young's modulus than copper may be used for the member 26.

[Example 2]
Next, Example 2 will be described with reference to FIG.
FIG. 7 is a conceptual diagram illustrating the configuration of the current collector plate in Example 2. In FIG. 7, (a) is a perspective view schematically showing the positive electrode current collector plate, and (b) is b in (a). (C) is a c direction arrow view of (a), (d) is a d direction arrow view of (a). Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Further, in the following description, the positive electrode current collector plate will be described, and the negative electrode current collector plate has the same configuration as the positive electrode current collector plate, and thus detailed description thereof will be omitted.

  What is characteristic in the present embodiment is that a part of the base portion 44a is made of a clad material with respect to the structure of the positive electrode current collector plate 44 of the first embodiment. The welded portion 44 b of the positive electrode current collector plate 44 has a constant width W, and the base material 45 is disposed over the entire surface facing the winding group 3, and the entire surface facing the battery can 1. The member 46 is arrange | positioned over.

  The base 44 a of the positive electrode current collector plate 44 has a base material 45 disposed over the entire surface facing the winding group 3, and the base material 45 is disposed on the surface facing the battery lid 6 on the opening hole 44 c side. And the member 46 is arrange | positioned at the welding part 44b side. That is, the entire welded portion 44 b of the positive electrode current collector plate 44 is made of the base material 45 and the clad material of the member 46, and the base portion 44 a is part of the welded portion 44 b side from the base material 45 and the member 46. Thus, the portion on the opening hole 44c side is made of the base material 45 alone.

  The portion of the base portion 44a on the side of the opening hole 44c is a portion that is caulked and fixed to the positive electrode connecting portion 14a and welded. By configuring such a part with the base material 45 alone, in addition to the effect of the first embodiment, the current resistance of the positive electrode current collector plate 44 can be made lower than that of the first embodiment and heat generation can be suppressed. Moreover, weight can be reduced by reducing the usage-amount of the member 46 in the positive electrode current collector plate 44 whole.

[Example 3]
FIG. 8 is a conceptual diagram illustrating the configuration of the current collector plate in Example 3. In FIG. 8, (a) is a perspective view schematically showing the positive electrode current collector plate, and (b) is b in (a). (C) is a c direction arrow view of (a), (d) is a d direction arrow view of (a). Note that the same components as those in the above-described embodiments are denoted by the same reference numerals, and detailed description thereof is omitted. Further, in the following description, the positive electrode current collector plate will be described, and the negative electrode current collector plate has the same configuration as the positive electrode current collector plate, and thus detailed description thereof will be omitted.

  What is characteristic in the present embodiment is that the width W2 of the member 46 is narrower than the width W1 of the base material 45 in the welded portion 44b with respect to the configuration of the positive electrode current collector plate 44 of the second embodiment. According to the present embodiment, in addition to the operational effects of the first embodiment, the amount of the member 46 used in the positive electrode current collector plate 44 can be further reduced as compared with the second embodiment, and the operational effects can be further improved.

[Example 4]
FIG. 9 is a conceptual diagram illustrating the configuration of the current collector plate in Example 4, in which (a) is a perspective view schematically showing the positive electrode current collector plate, and (b) is b in (a). A direction arrow view, (c) is a c direction arrow view of (a). Note that the same components as those in the above-described embodiments are denoted by the same reference numerals, and detailed description thereof is omitted. Further, in the following description, the positive electrode current collector plate will be described, and the negative electrode current collector plate has the same configuration as the positive electrode current collector plate, and thus detailed description thereof will be omitted.

  What is characteristic in the present embodiment is that the welded portion 44b is paired with the configuration of the positive electrode current collector plate 44 of the first embodiment. The positive electrode current collector plate 44 has a pair of welded portions 44b that are bent at the side ends of the base portion 44a and face each other. In the positive electrode current collector plate 44, a base material 45 is disposed on a surface facing the winding group 3, and a member 46 is disposed on a surface facing the battery lid 6 and the battery can 1. The base material 45 is continuously arranged over the entire surface of the base portion 44a facing the winding group 3 and the entire surface of the welding portion 44b facing the winding group 3, and the member 46 is formed of the base portion 44a. The entire surface of the surface facing the battery cover 6 of 44a and the entire surface of the welded portion 44b facing the wide side surface 1b in the battery can 1 are continuously arranged.

  The positive electrode current collector plate 44 having a pair of welds 44b is particularly suitable for supporting the wound group 3 having a large weight. The pair of welded portions 44b are welded and joined to, for example, two positive foil exposed portions projecting to one side in the winding axis direction in a configuration in which two winding groups 3 are arranged to overlap each other, or one winding group 3 The positive electrode metal foil exposed portion 34b of the winding group 3 is bundled by being divided into two on one side and the other side in the thickness direction of the wound group 3, and welded to each.

  The base material 45 of the positive electrode current collector plate 44 is made of aluminum or aluminum alloy, which is the same metal material as the positive electrode metal foil. The member 46 is made of a metal material having a higher Young's modulus than aluminum or aluminum alloy. Stainless steel is used. Therefore, the welding of the positive electrode current collector plate 44 and the positive electrode metal foil exposed portion 34b of the wound group 3 is a welding of the same kind of metal materials, and can be joined by a conventional welding method and is easily welded. be able to.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

1 Battery can
3 Twist group
6 Battery cover
12 Negative external terminal
14 Positive external terminal
24 Negative current collector
24a base
24b weld
25 Base material
26 parts
32 Negative electrode
32a Negative electrode mixture layer
32b Negative metal foil exposed part
33 Separator
34 Positive electrode
34a Positive mix layer
34b Exposed part of positive metal foil
35 Separator
44 Positive current collector
44a base
44b weld
45 Base material
46 parts
100 square rechargeable battery

Claims (9)

A square having a winding group in which the electrodes are wound, a battery container that houses the winding group, and a current collector plate that is connected to the electrode of the winding group in the battery container and supports the winding group. A secondary battery,
The current collector plate is composed of a clad material obtained by clad joining a base material and a member having a higher Young's modulus than the base material. The electrode has a metal foil,
2. The prismatic secondary battery according to claim 1, wherein a base material of the current collector plate is made of the same metal material as the metal foil and is welded to the metal foil. An external terminal exposed to the outside of the battery case;
A connection part that penetrates through the battery container and electrically connects the external terminal and the current collector plate, and
The prismatic secondary battery according to claim 2, wherein the connecting portion is made of the same metal material as the base material of the current collector plate and is welded to the base material of the current collector plate. The battery container has a bottomed rectangular battery can and a battery lid that closes an opening that opens at the top of the battery can.
The current collector plate has a base portion disposed opposite to the back surface of the battery lid, and is bent at a side end of the base portion and extends toward the bottom surface of the battery can along the side surface of the battery can. And having a weld to be welded to the metal foil,
The prismatic secondary battery according to claim 3, wherein the members of the current collector plate are continuously arranged between at least a part of the base and at least a part of the welded part. . The wound group has a positive electrode and a negative electrode,
The current collector plate has a positive electrode current collector plate that is connected to the positive electrode and supports the wound group, and a negative electrode current collector plate that is connected to the negative electrode and supports the wound group,
2. The prismatic secondary battery according to claim 1, wherein at least one of the positive electrode current collector plate and the negative electrode current collector plate is formed of the clad material. The positive electrode has a positive metal foil made of aluminum or an aluminum alloy,
The prismatic secondary battery according to claim 5, wherein a base material of the positive electrode current collector plate is made of aluminum or an aluminum alloy and is welded to the positive electrode metal foil. The negative electrode has a negative metal foil made of copper or a copper alloy,
The prismatic secondary battery according to claim 5, wherein a base material of the negative electrode current collector plate is made of copper or a copper alloy, and is welded to the negative electrode metal foil.   8. The prismatic two according to claim 6, wherein the member of the positive electrode current collector plate is any one selected from the group consisting of stainless steel, titanium, chromium, molybdenum, tungsten, vanadium, tantalum, and niobium. Next battery.   The prismatic secondary battery according to claim 6 or 7, wherein the member of the negative electrode current collector plate is any one selected from the group consisting of stainless steel, titanium, chromium, molybdenum, tungsten, vanadium, and tantalum. .

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