JP5986510B2 - Prismatic secondary battery - Google Patents

Description

  The present invention relates to a prismatic secondary battery.

  In recent years, secondary batteries with large capacity (Wh) have been developed as power sources for hybrid electric vehicles and pure electric vehicles, and among them, prismatic lithium ion secondary batteries with high energy density (Wh / kg). Is attracting attention.

  In a rectangular lithium ion secondary battery, a positive electrode in which a positive electrode active material is applied to a positive foil, a negative electrode in which a negative electrode active material is applied to a negative foil, and a separator for insulating each other are stacked Thus, a flat wound electrode group is formed as a power generation element. The wound electrode group is electrically connected to a positive electrode external terminal and a negative electrode external terminal provided on the battery lid of the battery container. The wound electrode group is accommodated in a battery can of the battery container, and the opening of the battery can is sealed and welded with a battery lid. A prismatic secondary battery is formed by injecting an electrolytic solution from a liquid injection hole of a battery container containing a wound electrode group, inserting a liquid injection stopper, and sealing welding by laser welding.

  Conventionally, in a sealed lithium ion secondary battery mounted on a vehicle or other equipment, gas is accumulated inside due to overcharge, excessive temperature rise, damage due to external force, etc. Pressure may increase. Therefore, a weak point for safety is formed in the battery case of the sealed battery. For example, there is a battery case in which a member that is deformed by the internal pressure of the battery is used at a part of the battery case, and the fragile portion is damaged by the deformation of the member. There have been proposed ones in which a current path is interrupted due to breakage of a fragile portion, and ones in which the inside and outside of a sealed battery are communicated to discharge gas.

  Patent Document 1 discloses a secondary battery having a battery cap assembly that can release the gas inside the battery when the internal pressure rises due to an abnormal operation of the battery and can shut off the energized state of the battery. ing. The secondary battery described in Patent Document 1 has a positive electrode member and an exhaust hole that are insulated on the top of a cap plate that covers the upper surface of the battery can, and a through hole formed in the cap plate and the positive electrode member. A rivet member that has a rivet protrusion that engages the cap plate and the positive electrode member by penetrating the positive electrode member, and a safety that is coupled to the lower end of the rivet member so that the exhaust hole is sealed. It has a member.

JP-A-11-162437

  However, since Patent Document 1 has a safety member serving as a current interruption mechanism coupled to the lower end of the rivet member, the volume of the wound electrode group that can be accommodated in the battery can is reduced, and the secondary battery There was a problem with increasing capacity.

  The present invention has been made in view of the above points, and an object of the present invention is to reduce the volume of the wound electrode group that can be accommodated in the battery can while having a safety member serving as a current interruption mechanism. And to provide a high-capacity prismatic secondary battery.

  A prismatic secondary battery of the present invention that solves the above-described problems is provided with a power generation element having an electrode, a battery can that houses the power generation element, a battery lid that seals the opening of the battery can, and the battery lid. A rectangular secondary battery having an external terminal and a current collecting terminal disposed in the battery can and connected to the electrode of the power generation element, wherein an electric current is provided between the current collecting terminal and the external terminal. A reversing terminal that is electrically connected and is deformed by an increase in the internal pressure of the battery can to cut off the electrical connection, and the reversing terminal is inserted in the through hole of the fixed shaft that is inserted into the opening hole of the battery lid It is characterized by being arranged in.

  According to the present invention, it is possible to provide a high-capacity secondary battery without having to reduce the volume of the wound electrode group that can be accommodated in the battery can while having a safety member serving as a current interruption mechanism. 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 which shows the structure of a square secondary battery. The perspective view which shows the winding electrode group. The exploded perspective view of a battery lid assembly. The exploded sectional view of the positive electrode terminal composition part. Sectional drawing which shows the state which attached the positive electrode external terminal to the battery cover. Sectional drawing which shows the state which crimped and fixed the positive electrode external terminal to the battery cover. Sectional drawing which shows the state which joined the positive electrode external terminal and the inversion component. Sectional drawing which shows the state which joined the inversion terminal and the positive electrode current collection terminal. The exploded sectional view of the negative electrode terminal composition part. Sectional drawing which shows the state which attached the negative electrode external terminal and the negative electrode current collection terminal to the battery cover. Sectional drawing which shows the state which crimped and fixed the negative electrode external terminal and the negative electrode current collection terminal to the battery cover. Sectional drawing which expanded and showed the principal part of the positive electrode terminal structure part. FIG. 7B is a cross-sectional perspective view in the direction of arrow B in FIG. 7A. FIG. 7B is a cross-sectional view illustrating a state where the reversing component illustrated in FIG. 7A is reversed. The figure in which the part with a weak part showed the form of another part.

  The prismatic secondary battery according to the present invention includes a wound electrode group obtained by flatly winding a positive electrode and a negative electrode via a separator, a battery can that houses the wound electrode group, and a battery that seals the battery can. A lid, an external terminal disposed on the battery lid, a current collecting terminal connected to the wound electrode group, and an inverting terminal for connecting the external terminal and the current collecting terminal. And the inversion terminal is arrange | positioned inside the axis | shaft of the fixed axis | shaft of an external terminal, and the current collection terminal is connected with the inversion terminal inside the axis | shaft. And a current collection terminal has a weak part which cuts a connection with an inversion terminal, and the weak part is provided in the perimeter of a connection part with an inversion terminal.

  Next, embodiments of the present invention will be described in detail below with reference to the drawings.

  As shown in FIG. 1, the rectangular secondary battery D <b> 1 includes a battery can 1 and a lid 2 that constitute a battery container. In the battery can 1, a wound electrode group 6 (FIG. 3) that is a power generation element is housed. The battery can 1 has a flat box shape having an upper opening, and is formed by deep drawing an aluminum alloy. The battery can 1 has a rectangular bottom wall part PB, a wide surface wall part PW that rises and confronts from a pair of long side parts of the bottom wall part PB, and a pair of short side parts of the bottom wall part PB. And a narrow side wall (opposing wall) PN. The opening of the battery can 1 is sealed by, for example, laser welding the lid 2.

  The lid 2 is made of, for example, an aluminum alloy that is the same material as the battery can 1 and has a flat plate shape that closes the opening of the battery can 1. The lid 2 is provided with a gas discharge valve 3 for cleaving at a preset pressure when the internal pressure of the battery container rises and releasing the gas to the outside. The gas discharge valve 3 is a thin film member made of the same metal material as the lid 2 or an alloy thereof, and is joined to the lid 2 by laser welding or the like. It may be formed integrally with the lid 2 by pressing or the like.

  FIG. 2 is an exploded view of the prismatic secondary battery shown in FIG.

  A wound electrode group 6, an insulating sheet 9, and an electrolytic solution (not shown) are accommodated in the internal space of the battery container constituted by the battery can 1 and the lid 2. The electrolyte is injected from an injection port 2A provided in the lid 2 in advance, and then the injection plug 5 is joined to the lid 2 by laser welding or the like, thereby sealing the inside of the battery. In addition, the secondary battery D1 of this embodiment is neutral in which the battery can 1 and the lid 2 have no polarity.

  The wound electrode group 6 attached to the lid 2 via current collecting terminals 26 and 36 is accommodated in the battery can 1 via an insulating sheet 9. Thereafter, the battery can 1 and the lid 2 are joined by welding or the like. The insulating sheet 9 is composed of a sheet member made of an insulating synthetic resin material, and wraps the wound electrode group 6 supported by the current collecting terminals 26 and 36 together with the current collecting terminals 26 and 36 from the outside. A short circuit between the battery can 1 and the wound electrode group 6 is prevented.

  As shown in FIG. 3, the wound electrode group 6 is wound in a state where the separator 6C, the negative electrode plate 6D, the separator 6C, and the positive electrode plate 6E are stacked in this order, and is flattened and formed into a flat shape. Has a round structure. A separator 6C is wound around the winding start end, and the separator 6C is wound around the winding end end several times. In order to prevent unwinding, the separator 6C disposed on the lower side of FIG. The end of the winding is stopped with a tape (not shown) coated with an adhesive on one side in advance.

  In the positive electrode plate 6E, a positive electrode active material mixture containing, for example, a lithium-containing transition metal composite oxide such as lithium manganate as a positive electrode active material on both surfaces of an aluminum alloy foil (positive electrode current collector) is substantially uniform and substantially uniform. A positive electrode uncoated portion 6A in which the positive electrode active material mixture is not coated is formed on one side along the longitudinal direction on both surfaces.

  On the other hand, in the negative electrode plate 6D, a negative electrode active material mixture containing a carbon material such as graphite capable of occluding and releasing lithium ions as a negative electrode active material on both surfaces of a copper alloy foil (negative electrode current collector) is substantially equal and substantially. A negative electrode uncoated portion 6B is formed which is uniformly coated and is coated with the negative electrode active material mixture on both sides along the longitudinal direction. The separators 6C and 6C are made of a microporous sheet material through which lithium ions can pass. In this example, a polyethylene sheet having a thickness of several tens of μm is used.

  FIG. 4 is an exploded perspective view of the battery lid assembly.

  A battery lid assembly is configured by attaching the positive terminal component 20 and the negative terminal component 30 to the battery lid 2. The power generation element assembly is configured by attaching the wound electrode group 6 to the battery lid assembly.

  The positive electrode terminal constituting part 20 and the negative electrode terminal constituting part 30 are arranged at positions separated from each other on one side and the other side in the long side direction of the lid 2. The positive electrode terminal component 20 includes a positive electrode external terminal 21, a fastening member 22, an external insulator 23, a seal member 24, an internal insulator 25, a positive electrode current collector terminal 26, a reverse terminal 27, and a caulking auxiliary member. 28 and a positive electrode current collector protrusion insulator 29.

  The positive electrode terminal component 20 includes a positive external terminal 21, a fastening member 22, an external insulator 23, and a seal member 24 superimposed on the surface side of the battery lid 2, and an internal insulator 25 and a caulking auxiliary member. 28 is superposed on the back side of the battery lid 2 and fixed integrally to the battery lid 2. Then, the positive current collecting projection insulator 263 is externally fitted to the positive current collecting projection 263 of the positive current collecting terminal 26 and inserted into the through hole 217 inside the shaft from the distal end side of the fixed shaft 216, and the positive current collecting terminal 26 is held in engagement with the internal insulator 25. Then, the reverse terminal 27 is inserted into the through hole 217 from the base end side of the fixed shaft 216 and laser welded to the positive external terminal 21 to seal the through hole 217. Then, the reversing terminal 27 is electrically connected to the positive current collecting protrusion 263 in the through hole 217 of the fixed shaft 216 to be assembled. The positive electrode current collecting terminal 26 is conductively connected to the positive electrode of the wound electrode group 6.

  The negative electrode terminal component 30 includes a negative electrode external terminal 31, a fastening member 32, an external insulator 33, a seal member 34, an internal insulator 35, and a negative electrode current collector terminal 36. The negative electrode terminal component 30 is configured such that the negative electrode external terminal 31, the fastening member 32, the external insulator 33, and the seal member 34 are overlapped on the surface side of the battery cover 2, and the fixed shaft of the negative electrode external terminal 31 is used as the battery cover. 2 is inserted into the opening hole 2B. Then, the internal insulator 35 and the negative electrode current collecting terminal 36 are overlapped on the back side of the battery lid 2 and are fixed to the battery lid 2 integrally by caulking the tip of the fixed shaft. Therefore, the negative electrode current collecting terminal 36 is conductively connected to the negative electrode external terminal 31 through the opening hole 2 </ b> B of the battery lid 2. The negative electrode current collecting terminal 36 is conductively connected to the negative electrode of the wound electrode group 6.

  The positive external terminal 21, the positive current collecting terminal 26, the reverse terminal 27, and the positive electrode caulking auxiliary member 28 are made of an aluminum alloy, and the negative external terminal 31 and the negative current collecting terminal 36 are made of a copper alloy. The inner insulators 25 and 35 and the outer insulators 23 and 33 are made of polypropylene (PP), and the seal members 24 and 34 are made of tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA). The positive external terminal 21, the negative external terminal 31 and the battery can 1 are kept insulative and airtight by the internal insulators 25 and 35, the external insulators 23 and 33, and the seal members 24 and 34.

  FIG. 5A is an exploded cross-sectional view of a positive electrode terminal component.

  The positive electrode terminal component 20 is placed between the inverting terminal 27 connected to the positive electrode current collecting terminal 26, the positive electrode external terminal 21 connected to the inverting terminal 27, and the positive electrode external terminal 21 via the battery lid 2. Inner insulator 25, positive electrode caulking auxiliary member 28 for caulking and fixing seal member 24 and outer insulator 23 to the upper part of battery lid 2, and positive electrode current collector protrusion insulation that insulates the outer periphery of positive electrode current collector protrusion 263 It has the body 29 and the fastening member 22 which penetrates the positive electrode external terminal 21.

  The positive external terminal 21, the reverse terminal 27, the fastening member 22, the external insulator 23, and the seal member 24 are installed outside the battery can, and the internal insulator 25, the positive current collector terminal 26, the positive current collector protrusion insulator 29, and the positive electrode The caulking auxiliary member 28 is installed inside the battery. Specifically, the external insulator 23 is disposed on the battery lid 2, and the fastening member 22 is disposed on the external insulator 23. The positive external terminal 21 is disposed on the external insulator 23 and the fastening member 22, and the reverse terminal 27 is disposed on the through hole 217 of the positive external terminal 21. An internal insulator 25 is disposed under the battery lid 2, a positive crimping auxiliary member 28 is disposed under the internal insulator 25, and the positive current collector terminal 26 is interposed via the positive current collector projection insulator 29. Be placed.

  FIG. 5B is a cross-sectional view showing a state in which the positive electrode external terminal is attached to the battery lid.

  The positive electrode external terminal 21 is passed through the opening hole 2B of the battery lid 2 and the through hole of the positive electrode caulking auxiliary member 28, and the respective members are overlapped to maintain insulation and airtightness. A positioning hole 217c used for positioning at the time of caulking is provided on the battery external side of the positive electrode external terminal 21, and the position of the battery lid 2 and the positive electrode caulking auxiliary member 28 can be accurately set by the positioning hole 217c. is there.

  FIG. 5C is a cross-sectional view showing a state in which the positive electrode external terminal is caulked and fixed to the battery lid.

  The positive electrode external terminal 21 includes a seal member 24, an external insulator 23, an internal insulator 25, and a positive electrode caulking auxiliary member 28 that are integrally fixed by caulking, so that insulation and airtightness of the outer peripheral portion of the positive electrode external terminal 21 are achieved. Kept.

  The positive external terminal 21 is provided with a caulking hole 217b on the distal end side of the fixed shaft 216 (see FIG. 5B), and is caulked by expanding the caulking hole 217b outward in the radial direction to form a caulking portion 216a. Is done. By the caulking by the caulking portion 216a, the positive electrode external terminal 21, the seal member 24, the external insulator 23, the internal insulator 25, and the positive electrode caulking auxiliary member 28 can maintain insulation and airtightness of the outer peripheral portion of the positive electrode external terminal 21. Is possible. The outside of the battery can of the crimped positive external terminal 21 is a flat surface, and the fastening member 22 is disposed adjacent to the flat surface.

  FIG. 5D is a cross-sectional view illustrating a state where the positive external terminal and the inversion terminal are joined.

  The reversing terminal 27 is inserted into the positioning hole 217c of the positive electrode external terminal 21 and joined to the positive electrode external terminal 21 by laser welding. By joining the inversion terminal 27 to the positive electrode external terminal 21 by laser welding, the airtightness of the through hole 217 of the positive electrode external terminal 21 is maintained, and the airtightness inside and outside the battery is completely ensured. The reversing terminal 27 is a component in which the semicircular portion 271 is reversed and deformed toward the outside of the battery due to a pressure difference between the inside of the battery and the outside of the battery when the internal pressure of the battery increases. The semicircular part 271 that reversely deforms is installed in the through hole 217 of the fixed shaft 216.

  FIG. 5E is a cross-sectional view showing a final assembled state of the positive electrode terminal component in which the inverting terminal and the positive electrode current collecting terminal are joined.

  The positive current collector terminal 26 has a cylindrical shape of the positive current collector projection 263 joined to the reversing terminal 27, and the positive current collector projection insulator 29 is externally fitted to the cylindrical positive current collector projection 263. The positive external terminal 21 is inserted into the through hole 217. Then, in the through hole 217 of the fixed shaft 216, the central portion of the top plate portion 265 is brought into contact with the top of the semicircular portion 271 of the reversing terminal 27 and is conductively joined to each other by, for example, laser welding. The positive electrode current collecting terminal 26 is fixed to the fixing rib 252 of the internal insulator 25 so that stress is not applied to the joint portion 265 c that is conductively joined to the reversing terminal 27 due to vibration or impact.

  In the present embodiment, as shown in FIGS. 5C and 5D, the reversing terminal 27 is first fixed to the positioning hole 217c of the positive external terminal 21, and then the positive current collecting terminal 26 is fixed to the internal insulator 25. However, the present invention is not limited to this order. For example, the positive electrode current collector terminal 26 may be fixed first, and the inverting terminal 27 may be fixed later.

  FIG. 6A is an exploded cross-sectional view of the negative electrode terminal component.

  The negative electrode terminal component 30 includes a negative electrode external terminal 31 connected to the negative electrode current collecting terminal 36, an internal insulator 35 placed between the negative electrode external terminal 31 and the battery lid 2, and an upper portion of the battery lid 2. In addition, a fastening member 32 that is disposed through the seal member 34 and the external insulator 33 and penetrates the negative electrode external terminal 31 is provided. The negative electrode external terminal 31, the fastening member 32, the external insulator 33, and the seal member 34 are installed outside the battery can, and the internal insulator 35 and the negative electrode current collecting terminal 36 are installed inside the battery.

  FIG. 6B is a cross-sectional view showing a state where the negative electrode external terminal and the negative electrode current collecting terminal are attached to the battery lid.

  The negative electrode external terminal 31 is passed through the opening hole 2B of the battery lid 2 and the through hole 36a of the negative electrode current collecting terminal 36, and the respective members are overlapped to maintain insulation and airtightness. A positioning hole 31A for caulking is provided on the battery external side of the negative electrode external terminal 31, and the position of the battery lid 2 and the negative electrode current collecting terminal 36 can be accurately set by the positioning hole 31A.

  FIG. 6C is a cross-sectional view showing a state where the negative electrode external terminal and the negative electrode current collecting terminal are caulked and fixed to the battery lid.

  The negative electrode external terminal 31 is electrically connected to the negative electrode current collector terminal 36 by caulking, and is electrically connected from the inside of the battery to the outside of the battery. The negative external terminal 31 is provided with a caulking hole 31B (see FIG. 6B), and is caulked by widening the caulking hole 31B, so that the negative external terminal 31 and the negative current collecting terminal 36 can be electrically connected. The battery can external side of the caulked negative electrode external terminal 31 is a flat surface, and a fastening member 32 is disposed adjacent to the flat surface.

  Next, the configuration of the positive electrode terminal component will be described in detail.

  For example, as shown in FIG. 4, the positive electrode external terminal 21 includes a flat plate portion 211 disposed along the upper surface of the battery lid 2, and a fixed shaft 216 that protrudes from the flat plate portion 211 and is inserted into the opening hole 2 </ b> B of the battery lid 2. And have. In this embodiment, the fixed shaft 216 is provided integrally with the flat plate portion 211. However, the fixed shaft 216 is not necessarily provided integrally. For example, the fixed shaft 216 is configured by a member different from the flat plate portion 211, such as caulking. May be fixed to each other. For example, as shown in FIG. 5A, the flat plate portion 211 is formed with an upper surface 213 to which a bus bar and the like are attached in contact with each other, and an insertion hole 214 through which the fastening member 22 is inserted and protruded from the upper surface 213.

  The fixed shaft 216 fixes the positive external terminal 21 to the battery lid 2 by caulking the tip that is inserted into the opening hole 2 </ b> B of the battery lid 2 and protrudes toward the back side of the battery lid 2. The fixed shaft 216 has a substantially cylindrical shape, and is provided with a through hole 217 penetrating along the center thereof. The through hole 217 has a hole diameter portion 217 a extending with a constant diameter, a caulking hole 217 b continuous from the hole diameter portion 217 a to the distal end side of the fixed shaft 216, and a diameter increased from the hole diameter portion 217 a on the proximal end side of the fixed shaft 216. Positioning hole 217c. The positioning hole 217 c is opened on the upper surface 213 of the flat plate portion 211. The caulking hole 217 b is expanded in diameter by caulking to form a caulking portion 216 a at the tip of the fixed shaft 216. The through-hole 217 has a configuration in which one end is opened toward the inside of the battery and the other end is opened toward the outside of the battery so as to communicate between the inside of the battery and the outside of the battery. The through-hole 217 is sealed by the reversing terminal 27 to isolate the inside of the battery from the outside of the battery.

  The external insulator 23 is interposed between the flat plate portion 211 of the positive electrode external terminal 21 and the battery lid 2 to insulate them. The external insulator 23 is formed with an opening 23a that is arranged coaxially with the opening hole 2B of the battery lid 2 and through which the fixed shaft 216 is inserted. The seal member 24 is inserted into the opening hole 2 </ b> B of the battery lid 2 to insulate and seal between the positive electrode external terminal 21 and the battery lid 2.

  The internal insulator 25 is disposed on the back surface of the battery lid 2 on the battery inner side, and is caulked and fixed integrally to the battery lid 2 by the fixed shaft 216 together with the caulking auxiliary member 28, and the battery lid 2 and the positive electrode caulking auxiliary member 28. And the positive electrode current collector terminal 26 is held. The positive electrode caulking auxiliary member 28 has a disk shape, and a hole through which the fixed shaft 216 can be inserted is provided at the center thereof.

  The inner insulator 25 is bent at the flat plate portion 251 disposed in contact with the lower surface of the battery lid 2 and the opposite side portions of the flat plate portion 251 so as to be separated in the long side direction of the battery lid 2. A pair of fixing ribs 252 facing each other is provided.

  The flat plate portion 251 of the internal insulator 25 is formed with an opening hole that communicates with the opening hole 2B of the battery lid 2 and through which the fixed shaft 216 is inserted. The pair of fixing ribs 252 are provided with engaging claws 253 that engage with the positive electrode current collecting terminals 26 at their respective distal ends.

  The positive electrode current collector terminal 26 is bent at a flat base portion 261 arranged in parallel along the back surface of the battery lid 2 and opposite sides of the base portion 261, and is separated in the short side direction of the battery lid 2. And a pair of current collectors 262 facing each other. The pair of current collectors 262 are ultrasonically bonded to the positive electrode connecting portions formed by compressing the positive electrode uncoated portion 6A of the wound electrode group 6 in two in the thickness direction of the wound electrode group 6. The

  The base 261 of the positive electrode current collecting terminal 26 is inserted between the pair of fixing ribs 252 and is engaged by the engaging claws 253.

  The positive current collecting terminal 26 has a positive current collecting projection 263 projecting from the center of the base 261. The positive current collecting protrusion 263 includes a cylindrical body 264 that is fitted into the hole diameter part 217 a of the fixed shaft 216 with the positive current collecting protrusion insulator 29 interposed therebetween, and a disc shape that closes the distal end side of the body 264. The top plate portion 265 is provided. The top plate portion 265 is formed thinner than the body portion 264, and is provided with a fragile portion 265a (see FIGS. 7A and 7B) that is broken by the deformation of the reverse terminal 27. The fragile portion 265 a is configured by a concave groove formed in a circumferential shape so as to surround the outer periphery of the joint portion 265 c joined to the reversing terminal 27. The concave groove may be formed continuously in a circumferential shape, or may be formed in a broken line shape at a predetermined interval.

  For example, as shown in FIG. 5B, the positive electrode current collector protrusion insulator 29 protrudes radially outward at the base end of the cylindrical portion 291 and the cylindrical portion 291 that is externally fitted to the body portion 264 of the positive current collector protrusion 263. A flange portion 292 interposed between the caulking portion 216a of the fixed shaft 216 and the base portion 261 of the positive electrode current collecting terminal 26, and a top plate portion 265 of the positive electrode current collecting protrusion 263 projecting radially inward from the tip of the cylindrical portion 291. It has the opposing part 293 which opposes the surrounding edge part. The facing portion 293 is formed in a ring shape and exposes the central portion of the top plate portion 265 including the joint portion 265c upward.

  The positive current collector terminal 26 is sandwiched between a pair of fixed ribs 252 with the positive current collector protrusions 263 inserted into the through holes 217 of the fixed shaft 216, and is engaged by the engaging claws 253. As a result, the inner insulator 25 is held. Therefore, the relative movement of the positive electrode current collecting terminal 26 in the vertical direction and the horizontal direction with respect to the battery lid 2 can be restricted, and the positive electrode current collecting terminal 26 can be securely fixed to the battery lid 2.

  In the positive electrode current collecting terminal 26, the top portion of the semicircular portion 271 of the reversing terminal 27 is brought into contact with the central portion of the top plate portion 265 defined by the fragile portion 265a to form a joint portion 265c.

  The inverting terminal 27 includes a dome-shaped semicircular portion 271 having a semicircular cross section, a flat plate-shaped enlarged portion 272 that radially expands outward from the semicircular portion 271, and an enlarged portion 272. It has a short-axis cylindrical rising portion 273 that is bent at the outer peripheral edge and rises in a direction away from the semicircular portion 271 along the axial direction.

  The reversing terminal 27 is inserted into the through hole 217 in a posture in which the semicircular portion 271 protrudes from the outside of the battery toward the inside of the battery, more specifically, from the positioning hole 217c toward the inside of the hole diameter portion 217a. The And the enlarged diameter portion 272 is in contact with the stepped surface between the hole diameter portion 217a of the through hole 217 and the positioning hole 217c, and the outer peripheral surface of the rising portion 273 is in contact with the inner peripheral surface of the positioning hole 217c. Is done. The semicircular portion 271 is opposed to the positive electrode current collector projection 263 exposed at the center position than the opposed portion 293 of the positive electrode current collector projection insulator 29, and the top of the semicircular portion 271 is located at the central portion of the top plate portion 265. Abutted.

  The rising portion 273 has a tapered shape that gradually increases in diameter as it moves away from the enlarged diameter portion 272, and is press-fitted into a positioning hole 217c having a constant diameter. Therefore, the rising portion 273 can be pressed against the inner peripheral surface of the positioning hole 217c with a predetermined pressing force, and the reversing terminal 27 can be temporarily fixed in a state where it is positioned in the through hole 217.

  The reversing terminal 27 is laser welded to the positive external terminal 21 from the state temporarily fixed in the positioning hole 217c. In laser welding, the outer peripheral surface of the rising portion 273 and the inner peripheral surface of the positioning hole 217c are joined over the entire periphery. Therefore, the through-hole 217 is completely sealed by the reversing terminal 27 and is separated from the inside of the battery and the outside of the battery.

  The reversing terminal 27 is joined by laser welding the top of the semicircular portion 271 to the top plate portion 265 of the positive current collecting projection 263.

  FIG. 7A is an enlarged cross-sectional view showing the main part of the positive electrode terminal component, and FIG. 7B is a cross-sectional perspective view in the direction of arrow B in FIG. 7A.

  In the positive electrode terminal component 20, a weak portion 265 a is formed on the positive current collector protrusion 263 of the positive current collector terminal 26 in order to cut off electrical conduction by the reverse terminal 27 reversed by the internal pressure of the battery and the reversed force. Yes. The top plate portion 265 of the positive electrode current collection projection 263 where the fragile portion 265a is formed is formed into a shape that is easily broken by press-molding the upper portion of the cylindrical body portion 264 into a thin wall. The fragile portion 265a is continuously formed in a circumferential shape so as to surround the outer periphery of the joint portion 265c.

  As shown in FIG. 7B, the top plate portion 265 of the positive electrode current collecting terminal 26 has a passage hole 265b for equalizing the pressures on the reversing terminal 27 side and the battery inner side so as not to cause a difference. Is provided. The passage hole 265b is provided so as to be disposed between the fragile portion 265a and the joint portion 265c, and several circular through holes are vacant.

  FIG. 8 is a cross-sectional view showing a state where the reversing component shown in FIG. 7A is reversed.

  In the reversing terminal 27, the semicircular portion 271 is reversed and deformed toward the outside of the battery due to an increase in the battery internal pressure, and the joint portion 265c of the top plate portion 265 is pulled upward. The top plate portion 265 is broken at the fragile portion 265 a, and a central portion which is a part of the top plate portion 265 is cut off from the body portion 264 side and completely separated from the positive electrode current collection protrusion 263. Therefore, the electrical connection between the positive electrode current collecting terminal 26 and the positive electrode external terminal 21 is interrupted. When the current is interrupted by the deformation of the inverting terminal 27, it can be visually confirmed that the semicircular portion 271 of the inverting terminal 27 protrudes upward from the through hole 217, so that the current is interrupted. It can be easily determined whether or not.

  FIG. 9 is a diagram showing another embodiment, in which a part having a weak part is shown as another part.

  The positive electrode current collection protrusion 263 may be provided separately from the base 261 and may be joined by welding or the like. For example, an engagement hole 261a is formed in the base portion 261, and a positive electrode current collection protrusion 263 is fitted and joined by laser welding to be integrated. The positive electrode terminal component 20 is formed in the same form as the assembly process of FIG. 5 after the positive electrode current collector projection 263 is joined to the base 261 and the positive electrode current collector terminal 26 is assembled.

  According to this embodiment described above, the following operational effects can be achieved.

  The prismatic secondary battery D1 has an inverting terminal 27 that electrically connects the positive electrode current collecting terminal 26 and the positive electrode external terminal 21 and is deformed by an increase in the internal pressure of the battery can 1 to cut off the electric connection. Since the reversing terminal 27 is disposed in the through hole 217 of the fixed shaft 216 inserted through the opening hole 2B of the battery lid 2, the reversing terminal 27 protrudes from the battery cover 2 into the battery can 1. Can be prevented. Therefore, a high-capacity prismatic secondary battery D1 can be obtained without reducing the volume of the wound electrode group that can be accommodated in the battery can.

  According to the present invention, it is possible to provide a high-capacity secondary battery without having to reduce the volume of the wound electrode group that can be accommodated in the battery can while having a safety member serving as a current interruption mechanism. And since the inversion terminal 27 was comprised with the member different from the positive electrode external terminal 21, a current interruption | blocking mechanism can be created with high precision and easily.

  As long as the characteristics of the present invention are not impaired, the present invention is not limited to the above-described embodiments, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. .

D1: secondary battery 1: battery can 2: battery lid 3: gas discharge valve 5: injection plug 6: wound electrode group 6A: positive electrode uncoated part 6B: negative electrode uncoated part 6C: separator 6D: negative electrode plate
6E: Positive electrode plate 9: Insulating sheet 21: Positive electrode external terminal 217: Through hole
217b: Caulking hole 217c: Positioning hole 22: Fastening member
23: External insulator 24: Seal member 25: Internal insulator 252: Fixed rib
26: Positive current collecting terminal 263: Positive current collecting protrusion 265a: Fragile portion 265b: Pressure passage hole 265c: Joint portion 27: Inversion terminal 28: Positive electrode caulking auxiliary member
29: Positive current collector projection insulator 31: Negative external terminal 31A: Negative terminal positioning hole
31B: Negative electrode caulking hole 32: Negative electrode fastening member 33: External insulator 34: Seal member 35: Internal insulator 36: Negative electrode collector terminal

Claims (10)

A power generation element having an electrode; a battery can that houses the power generation element; a battery lid that seals an opening of the battery can; an external terminal that is disposed on the battery lid; and the battery can that is disposed in the battery can A rectangular secondary battery having a current collecting terminal connected to an electrode of a power generation element,
Electrically connecting between the current collecting terminal and the external terminal, and having an inverting terminal that is deformed by an increase in internal pressure of the battery can and cuts off the electrical connection,
The reversing terminal is disposed in a through hole of a fixed shaft that is inserted through an opening hole of the battery lid, and does not protrude into the battery can from the lower end of the through hole .   2. The prismatic secondary battery according to claim 1, wherein the current collecting terminal includes a current collecting protrusion that is joined to the reversing terminal in the through hole of the fixed shaft.   The current collecting protrusion has a joint portion joined to the reversing terminal, and a fragile portion that breaks due to deformation of the reversing terminal and separates the joining portion from the current collecting protrusion. The prismatic secondary battery described in 1.   The prismatic secondary battery according to claim 3, wherein the fragile portion is provided in a circumferential shape so as to surround an outer periphery of the joint portion.   The current collection protrusion has a cylindrical body portion that is fitted into the through hole of the fixed shaft, and a top plate portion that closes a tip of the body portion, and the joint portion is connected to the top plate portion. The prismatic secondary battery according to claim 3 or 4, wherein the fragile portion is formed.   6. The prismatic secondary battery according to claim 5, wherein the top plate portion is provided with a passage hole for equalizing the pressure on the reversing terminal side and the battery inner side.   The prismatic secondary battery according to claim 6, wherein the passage hole is disposed between the joint portion and the fragile portion. The reversing terminal has a dome-shaped semicircular shape portion having a semicircular cross section,
The square secondary according to any one of claims 1 to 7, wherein the semicircular portion is disposed in the through hole in a posture state in which the semicircular portion projects from the outside of the battery toward the inside of the battery. battery. The reversing terminal is a flat-plate-shaped widened portion that radially expands radially outward from the semicircular-shaped portion, and the semicircular shape is bent along the axial direction by being bent at the outer peripheral edge of the widened portion. A short-axis cylindrical rising part that rises in a direction away from the part, and
9. The square-shaped two-piece structure according to claim 8, wherein an outer peripheral surface of the rising portion is in contact with an inner peripheral surface of the through hole and is joined over the entire periphery to seal the through hole. Next battery. The fixed shaft has a positioning hole having a constant diameter,
The prismatic secondary battery according to claim 9, wherein the rising portion has a tapered shape that gradually increases in diameter as it moves in a direction away from the semicircular shape portion.

Images