JP6393598B2 - Cylindrical secondary battery - Google Patents

Description

  The present invention relates to a cylindrical secondary battery.

  A power generation element of a cylindrical secondary battery represented by a lithium secondary battery is formed by winding a positive electrode coated with a positive electrode mixture and a negative electrode coated with a negative electrode mixture around a shaft core via a separator. Configured. The power generation element has a plurality of leads called tabs protruding from both ends of the power generation element, and is joined to the current collecting member for each of the positive and negative electrodes. A positive current collector is disposed on the upper side of the power generation element, and the positive current collector and the lid unit are connected by a flexible lead plate (conductive lead).

  The battery can accommodates a power generation element and an electrolyte, and a lid unit is caulked in the opening via an insulating member and sealed.

  As a method of connecting the positive electrode current collecting member and the lid unit with a conductive lead, the following method is known. The conductive lead is formed by bundling a plurality of aluminum thin plates, and both ends of the bundled lead are fixed and connected to the positive electrode current collecting member and the lid unit by laser welding or the like. At this time, the conductive lead has flexibility, but at the same time, since the portions other than the welded portion are not fixed, there is a possibility that the conductive lead contacts the current collecting member or the lid unit. In this case, there is a possibility that the temperature rises due to the current diversion or current concentration at the contact portion and the battery function is lowered.

  Patent Document 1 discloses a method of preventing a portion other than the welded end of a flexible conductive lead connecting a positive electrode current collecting member and a lid unit from coming into contact with the lid or the current collecting member. Specifically, an invention has been disclosed in which an insulating film is formed by wrapping an adhesive film around a conductive lead or applying an insulating paint to prevent diversion and current concentration due to contact and maintain a battery function.

JP 2011-216398 A

  In Patent Document 1, as a method for forming an insulating film on a conductive lead, winding a tape and applying an insulating paint are cited. However, these methods may reduce the flexibility of the conductive lead.

  The conductive lead can be flexible because a plurality of aluminum thin plates are fixed at both ends and the other portions can move freely one by one. When the tape is wound, the flexibility is lowered because the tape is fixed to one. If the flexibility is lowered, the tape may be damaged when vibration is applied to the battery, and it may be difficult to ensure insulation.

  In addition, when an insulating coating is applied to the surface of the conductive lead with a certain thickness and an insulating film is formed, in addition to a decrease in flexibility due to curing of the insulating film, there is a concern about the flexibility of the increased thickness. Also in this case, when the battery is vibrated, the insulating paint is peeled off, and it may be difficult to ensure insulation.

  In order to solve the above-mentioned problems, a cylindrical secondary battery according to the present invention includes a power generation element in which a positive electrode and a negative electrode are wound around a shaft core via a separator, and a collector connected to the power generation element. A conductive ring, a current collecting ring, one end of which is connected, a conductive lead made of a plurality of metal foils, and a connecting plate connected by folding the other end of the conductive lead, and the conductive lead is covered with an insulating bag And there is a gap between the conductive lead and the insulating bag.

  By using the present invention, it is possible to provide a cylindrical secondary battery that maintains flexibility while ensuring insulation of the conductive leads.

Cross section of cylindrical secondary battery Exploded perspective view of cylindrical secondary battery Exploded sectional perspective view of power generation element Assembly drawing of conductive lead and insulating bag according to first embodiment (a) to (c) The expanded sectional view in the middle of the process of the electroconductive lead peripheral part which concerns on 1st embodiment Enlarged sectional view of the periphery of the conductive lead according to the first embodiment Assembly drawing (a) to (c) of conductive leads and insulating bags according to the second embodiment Assembly drawing of conductive lead and insulating bag according to third embodiment (a) to (c)

<First embodiment>
Hereinafter, embodiments of a power storage device according to the present invention will be described with reference to the drawings.

  FIG. 1 is an enlarged cross-sectional view showing a first embodiment of a cylindrical secondary battery.

  The cylindrical secondary battery 1 includes a battery case 4 including a cylindrical battery can 2 having a bottom and an upper opening, and a hat-type battery lid 3 that seals the top of the battery can 2. Inside the battery container 4, constituent members for power generation described below are accommodated, and a non-aqueous electrolyte 5 is injected.

  In the cylindrical battery can 2, a groove 2 a protruding to the inside of the battery can 2 is formed on the opening 2 b provided on the upper end side.

  A power generation element 10 is arranged inside the battery can 2. The power generation element 10 includes an elongated cylindrical shaft core 15 having a hollow portion along the axial direction, and a positive electrode 11 and a negative electrode 12 wound around the shaft core 15. The hollow portion of the cylindrical shaft core 15 has a different cross-sectional shape in a plane perpendicular to the axial direction in the axial direction (vertical direction in the drawing). The cross-sectional shape above the hollow portion is a track shape formed by parallel portions and curved portions. The cross-sectional shape below the hollow portion is a circle having a diameter smaller than the width of the upper parallel portion. A cylindrical positive electrode current collecting ring 25 is press-fitted into the upper hollow portion 15a. The positive electrode current collecting ring 25 includes a disc-shaped base portion 25a, a lower cylindrical portion 25b that protrudes toward the shaft core 15 at the inner peripheral portion of the base portion 25a, and press-fitted into the inner surface of the shaft core 15, and a battery at the outer peripheral edge. And an upper cylindrical portion 25c protruding toward the lid 3 side. The positive electrode current collecting ring 25 is fixed and supported on the upper end portion of the shaft core 15 by the lower cylindrical portion 25b.

  The positive electrode tab 16 of the positive electrode is welded to the upper cylindrical portion 25 c of the positive electrode current collecting ring 25. The positive electrode current collecting ring 25 is made of, for example, an aluminum-based metal, and the positive electrode tab 16 and the pressing member 28 of the positive electrode are welded to the outer periphery of the upper cylindrical portion 25c. A number of the positive electrode tabs 16 are brought into close contact with the outer periphery of the upper cylindrical portion 25c of the positive electrode current collecting ring 25, and a pressing member 28 is wound around the outer periphery of the positive electrode tab 16 in a ring shape and temporarily fixed. In this state, ultrasonic welding is performed. Are joined together.

  A step portion 15b having a small outer diameter is formed on the outer periphery of the lower end portion of the shaft core 15, and a negative electrode current collecting ring 21 is press-fitted and fixed to the step portion 15b. The negative electrode current collector ring 21 is formed of, for example, a copper-based metal, and an opening 21b that is press-fitted into the step portion 15b of the shaft core 15 is formed in a disk-shaped base portion 21a. An outer peripheral cylindrical portion 21c that protrudes toward is formed. An opening 21 d (see FIG. 2) for allowing the nonaqueous electrolytic solution 5 injected into the hollow shaft of the shaft core 15 to penetrate into the power generation element 10 is formed in the base portion 21 a of the negative electrode current collecting ring 21.

The negative electrode tab 17 of the negative electrode is joined to the outer peripheral cylindrical portion 21 c of the negative electrode current collecting ring 21.
The negative electrode tab 17 and the pressing member 22 of the negative electrode are welded to the outer periphery of the outer peripheral cylindrical portion 21 c of the negative electrode current collecting ring 21. A number of negative electrode tabs 17 are brought into close contact with the outer periphery of the outer peripheral cylindrical portion 21c of the negative electrode current collector plate 21, and the holding member 22 is wound around the outer periphery of the negative electrode tab 17 in a ring shape and temporarily fixed, and is welded in this state. . A connection lead plate 50 is joined to the base 21a of the negative electrode current collecting ring 21 by resistance welding, laser welding, or the like.

  A large number of positive electrode tabs 16 are welded to the positive electrode current collecting ring 25, and a large number of negative electrode tabs 17 are welded to the negative electrode current collecting ring 21, whereby the positive electrode current collecting ring 25, the negative electrode current collecting ring 21, and the power generation element 10 are formed. The power generation unit 20 is formed as a unit. A predetermined amount of non-aqueous electrolyte 5 is injected into the battery can 2. As an example of the nonaqueous electrolytic solution 5, a solution in which a lithium salt is dissolved in a carbonate-based solvent is raised.

  FIG. 2 is an exploded perspective view of the cylindrical secondary battery.

  A cylindrical positive current collecting ring 25 is press-fitted above the hollow portion of the cylindrical shaft core 15. The positive electrode current collecting ring 25 is made of, for example, an aluminum-based metal. An opening 25d for discharging a gas generated inside the battery is formed in the base 25a of the positive electrode current collecting ring 25. The opening 25 e formed in the positive electrode current collecting ring 25 is for inserting an electrode rod (not shown) for welding the connection lead plate 50 to the battery can 2. The electrode rod is inserted into the hollow portion of the shaft core 15 through the opening 25e formed in the positive electrode current collecting ring 25, and the connecting lead plate 50 is pressed against the inner surface of the bottom portion 2c of the battery can 2 at the tip thereof to perform resistance welding. Thus, the power generation unit 20 is fixed to the bottom 2c of the battery can 2. Further, the bottom surface of the battery can 2 connected to the negative electrode current collecting ring 21 acts as one output terminal, and the electric power stored in the power generation element 10 can be taken out from the battery can 2. A flexible conductive lead 41 formed by laminating a plurality of aluminum foils is joined to the upper surface of the base portion 25a of the positive electrode current collecting ring 25 by welding one end thereof.

  A battery lid unit 30 is disposed on the upper cylindrical portion 25 c of the positive electrode current collecting ring 25. The battery lid unit 30 includes a ring-shaped insulating plate 34, a connecting plate 35 fitted in an opening 34a provided in the insulating plate 34, a diaphragm 37 welded to the connecting plate 35, and a diaphragm 37 by caulking and welding. The battery cover 3 is fixed.

  The insulating plate 34 has a ring shape made of an insulating resin material having a circular opening 34 a and is placed on the upper cylindrical portion 25 c of the positive electrode current collecting ring 25.

  The insulating plate 34 has an opening 34a and a side 34b protruding downward. A connecting plate 35 is fitted in the opening 34 a of the insulating plate 34. The other end of the conductive lead 41 is welded and joined to the lower surface of the connection plate 35.

  The connection plate 35 is made of an aluminum-based metal and has a substantially dish shape that is substantially uniform except for the central portion and is bent to a slightly lower position on the central side. A projection 35a that is thin and formed in a dome shape is formed at the center of the connection plate 35, and a plurality of openings 35b are formed around the projection 35a. The opening 35b has a function of releasing gas generated inside the battery. The protrusion 35 a of the connection plate 35 is joined to the bottom surface of the center portion of the diaphragm 37 by resistance welding or friction stir welding. The diaphragm 37 is formed of an aluminum-based metal, and has a circular cut 37 a centering on the center portion of the diaphragm 37. The cut 37a is formed by crushing the upper surface side into a V shape by pressing and thinning the remainder. The diaphragm 37 is provided for ensuring the safety of the battery, and has a function of cleaving at the cut 37a and releasing the internal gas when the internal pressure of the battery increases.

  The diaphragm 37 fixes the peripheral edge of the battery lid 3 at the peripheral edge. As shown in FIG. 2, the diaphragm 37 initially has a side wall 37 b erected vertically at the peripheral portion toward the battery lid 3 side. The battery lid 3 is accommodated in the side wall 37b, and the side wall 37b is bent and fixed to the upper surface side of the battery lid 3 by caulking.

  The battery lid 3 is made of iron such as carbon steel, nickel plated on both front and back surfaces, a disc-shaped peripheral edge 3a that contacts the diaphragm 37, and a cylindrical portion 3b that protrudes upward from the peripheral edge 3a. Having a hat shape. An opening 3c is formed in the cylindrical portion 3b. The opening 3c is for releasing gas to the outside of the battery when the diaphragm 37 is cleaved by the gas pressure generated inside the battery. The battery lid 3 acts as one power output end, and the stored electric power can be taken out from the battery lid 3.

  A gasket 43 made of an insulating member that covers the caulked portion between the diaphragm 37 and the battery lid 3 is provided. The gasket 43 is made of rubber, and is not intended to be limited, but one example of a preferable material is a fluorine-based resin.

  The gasket 43 has a shape having an outer peripheral wall portion 43b that is formed to rise substantially vertically toward the upper direction at the peripheral edge of the ring-shaped base portion 43a.

  Then, the outer peripheral wall 43b of the gasket 43 is bent together with the battery can 2 by pressing or the like, and the diaphragm 37 and the battery lid 3 are crimped by the base 43a and the outer peripheral wall 43b so as to be pressed in the axial direction. Thereby, the battery lid unit 30 in which the battery lid 3, the diaphragm 37, the insulating plate 34 and the connection plate 35 are integrally formed is fixed to the battery can 2 via the gasket 43, and the insulating plate 34 is attached to the power generation unit 20. The power generation unit 20 is pressed against the can bottom side of the battery can 2 in contact with the positive electrode current collecting ring 25.

  FIG. 3 is an exploded cross-sectional perspective view showing details of the structure of the power generation element 10.

  The power generating element 10 has a structure in which a positive electrode 11, a negative electrode 12, and first and second separators 13 and 14 are wound around an axis 15.

  The shaft core 15 is formed of an insulating material such as PP (polypropylene) and has a hollow cylindrical shape. A first separator 13, a negative electrode 12, a second separator 14, and a positive electrode 11 are sequentially stacked and wound on the shaft core 15. Inside the innermost negative electrode 12, the first separator 13 and the second separator 14 are wound several times (one turn in FIG. 3). The first separator 13 and the second separator 14 are formed of an insulating porous body.

  In the innermost circumference (axial core side), the beginning of the negative electrode 12 extends in the circumferential direction from the beginning of the positive electrode 11. Further, at the outermost periphery (battery can side), the negative electrode 12 is wound more outward than the positive electrode 11, and the end of the negative electrode 12 is extended in the circumferential direction from the end of the positive electrode 11. Yes. A second separator 14 is wound around the outer periphery of the outermost negative electrode 12. The end of the second separator 14 on the outermost periphery is stopped with an adhesive tape 19. In some cases, the first separator 13 and the second separator 14 are wound several times on the outermost periphery and then stopped by the adhesive tape 19.

  The positive electrode 11 is formed of an aluminum foil, has a long shape, and includes a positive electrode metal foil 11a and a positive electrode mixture layer 11b in which a positive electrode mixture is applied to both surfaces of the positive electrode metal foil 11a. The upper side edge extending in the longitudinal direction of the positive electrode metal foil 11a is a positive electrode foil exposed portion 11c where the positive electrode mixture is not applied and the positive electrode metal foil 11a is exposed. A large number of positive electrode tabs 16 protruding upward along the axis of the shaft core 15 are integrally formed at equal intervals on the positive electrode foil exposed portion 11c.

  The positive electrode mixture includes a positive electrode active material, a positive electrode conductive material, and a positive electrode binder. Examples of the positive electrode active material include lithium oxides such as cobalt, manganese, and nickel.

  Examples of the positive electrode binder include polyvinylidene fluoride (PVDF) and fluororubber.

  Examples of the method for applying the positive electrode mixture to the positive electrode metal foil 11a include a roll coating method and a slit die coating method. A slurry obtained by kneading a dispersion solution in a positive electrode mixture is uniformly applied to both surfaces of an aluminum foil having a thickness of 20 μm, dried, pressed, and cut. An example of the coating thickness of the positive electrode mixture is about 40 μm on one side. When the positive electrode metal foil 11a is cut, the positive electrode tab 16 is integrally formed. All the positive electrode tabs 16 have substantially the same length.

  The negative electrode 12 includes a negative electrode metal foil 12a formed of copper foil and having a long shape, and a negative electrode mixture layer 12b in which a negative electrode mixture is applied to both surfaces of the negative electrode metal foil 12a. The side edge on the lower side extending in the longitudinal direction of the negative electrode metal foil 12a is a negative electrode foil exposed portion 12c where the negative electrode mixture is not applied and the copper foil is exposed. A large number of negative electrode tabs 17 extending in the direction opposite to the positive electrode tab 16 along the axis of the shaft core 15 are integrally formed at equal intervals on the negative electrode foil exposed portion 12c.

  The negative electrode mixture includes a negative electrode active material, a negative electrode binder, and a thickener. An example of the negative electrode active material is graphite carbon.

  Examples of the method for applying the negative electrode mixture to the negative electrode metal foil 12a include a roll coating method and a slit die coating method.

  A slurry obtained by kneading a dispersion solvent in a negative electrode mixture is uniformly applied to both sides of a rolled copper foil having a thickness of 10 μm, dried, and then cut. An example of the coating thickness of the negative electrode mixture is about 40 μm on one side. When the negative electrode metal foil 12a is cut by pressing, the negative electrode tab 17 is integrally formed. All the negative electrode tabs 17 have substantially the same length.

  The widths of the first and second separators 13 and 14 are larger than the width of the negative electrode mixture layer 12 b of the negative electrode 12. The width of the negative electrode mixture layer 12 b of the negative electrode 12 is larger than the width of the positive electrode mixture layer 11 b of the positive electrode 11. The width and length of the negative electrode mixture layer 12b are made larger than the width and length of the positive electrode mixture layer 11b, and the entire region of the positive electrode mixture layer 11b is covered with the negative electrode mixture layer 12b. In the case of a lithium ion secondary battery, lithium, which is a positive electrode active material, is ionized, penetrates the separator, and is occluded by the negative electrode active material. In this case, if the negative electrode active material is not formed on the negative electrode side and the negative electrode metal foil 12a is exposed, lithium is deposited on the negative electrode metal foil 12a, causing an internal short circuit. As described above, by covering the entire region of the positive electrode mixture layer 11b with the negative electrode mixture layer 12b, it is possible to prevent such an internal short circuit due to lithium deposition.

  The first separator 13 and the second separator 14 are each formed of, for example, a polyethylene porous film having a thickness of 40 μm.

  4A to 4C show a detailed view of the conductive lead 41 and the insulating bag 44 according to the present embodiment and a view after assembly. 4A shows the conductive lead 41, FIG. 4B shows the insulating bag 44, and FIG. 4C shows the conductive lead 41 passed through the insulating bag 44. The insulating bag 44 is formed into a tube shape by processing an insulating film into a bag shape and opening both ends, and the conductive leads 41 are inserted therein. The configuration of the present invention can be realized by connecting both ends of the conductive lead 41 integrated with the insulating bag 44 to the positive electrode current collector ring 25 and the lid unit 30. Alternatively, it is possible to connect either the positive electrode current collecting ring 25 or the lid unit 30 to the conductive lead 41 first, and then cover the conductive lead 41 with the insulating bag 44 and connect the other member.

  Examples of the flexible material having insulation and resistance to electrolytic solution include olefin-based resins such as polyethylene and polypropylene, which are common as materials for separators and the like. In addition, it is preferable that the film used for the insulating bag 44 is thinner in consideration of flexible movement. When using the above-mentioned material, it is preferable that the thickness of the specific insulating bag 44 is 0.02 mm or more and 0.50 mm or less. The thickness of the insulating bag 44 is set to 0.02 mm or more in consideration of the strength and insulating properties of the insulating bag 44. If the thickness is further reduced, it is difficult to ensure the insulating properties. On the other hand, the thickness of the insulating bag 44 is set to 0.50 mm or less in consideration of flexibility. If the thickness is larger than this, the insulating bag 44 is difficult to bend and it is difficult to ensure flexibility.

  By providing a sufficient gap between the conductive lead 41 and the insulating bag 44, the flexibility of the conductive lead 41 can be maintained. In other words, in the present invention, since the insulating bag 44 is slidably held with a gap between the conductive lead 41 and the conductive lead 41 and the insulating bag 44 are not fixed, the conductive lead 41 and the insulating lead 44 are insulated. The flexibility of the bag 44 is maintained.

  FIG. 5 is an embodiment of the present invention, and is a cross-sectional view of the periphery of the conductive lead 41 in the process before caulking, that is, after the connection between the lid unit 30 and the conductive lead 41 and before the liquid injection. The end portion 41b of the conductive lead is connected to the lid unit 30 and the other end portion 41c of the conductive lead is connected to the positive current collecting ring 25. The central conductive lead 41 covered with the insulating bag 44 is flexible. Is maintained. The conductive lead 41, the connecting plate 35 constituting the lid unit 30 and connected to the conductive lead 41, and the positive current collecting ring 25 also connected to the conductive lead 41 are both made of an aluminum-based metal. Easy connection by laser welding. The connected lid unit 30 is supported by the conductive leads 41 but is not fixed. In the step of injecting the electrolytic solution, the electrolytic solution passes through the central portions of the hollow positive electrode current collecting ring 25 and the shaft center 15 and is filled in the power generation element 10. For this reason, the lid unit 30 connected to the flexible conductive lead 41 can change the position above the opening, and the lid unit 30 does not hinder the liquid injection process.

  FIG. 6 is a cross-sectional view of the periphery of the conductive lead 41 in the caulking process according to the embodiment of the present invention. In this step, the groove 2 a provided in the battery can 2 is covered with the lid unit 30, and the battery can 2 and the lid unit 30 are caulked through the gasket 43 to ensure the inside of the battery can 2. . At this time, the conductive lead 41 is housed so as to be folded into a space between the positive electrode current collecting ring 25 and the lid unit 30.

  The conductive lead 41 should be connected only at one end 41b to the lid unit 30 and at the other end 41c to the positive electrode ring 25, but is folded after being crimped. The folded portion 41a may come into contact with the lid unit 30 or the positive electrode current collecting ring 25.

  At this time, since the surface of the working part including the folded part 41a of the conductive lead 41 is insulated, it is possible to prevent the shunting and power concentration at the contact part. In the embodiment of the present invention, since the conductive lead 41 is covered with the insulating bag 44, it is possible to maintain the flexibility as well as the insulating property of the operating part of the insulating lead 41.

  The length L (see FIG. 4) of the insulating bag 44 is the maximum length between the end 41b and the end 41c. By setting the length of the insulating bag to the length between the end portion 41b and the end portion 41c, the conductive leads 41 other than the end portions 41b and 41c can be covered, and the insulation reliability is highest.

  On the other hand, considering the productivity, the length of the insulating bag is not necessarily the length between the end portion 41b and the end portion 41c because of the productivity. In order to achieve both productivity and insulation, it is preferable that the insulating bag 44 has a length that does not reach the end portion 41 b while covering the folded portion 41 a of the conductive lead 41. By setting the length L of the insulating bag 44 to the length that does not reach the end portion 41b while covering the folded portion 41a, it is possible to ensure the clearance between the end portions 41b and 41c and the insulating bag 44 during welding. It becomes. Therefore, it becomes easy to weld at the time of welding, and productivity improves. In addition, if the folded portion 41a is covered with the insulating bag 44 as a minimum, the insulating bag 44 is fixed between the conductive lead 41 and the base portion 25a of the positive current collecting ring 25 and at each of the bent portions 41a. Become. Accordingly, displacement of the insulating bag 44 due to vibration is suppressed, and sufficient insulation is ensured. Further, since the folded portion 41a of the conductive lead 41 is covered with the insulating bag 44, there is no possibility that the positive electrode current collecting ring 25 and the conductive lead 41 are in contact with each other, and the insulation reliability is improved.

  In other words, the length L of the insulating bag 44 is preferably such that the length from the end portion 41c to the folded portion 41a of the conductive lead 41 <L <the length from the end portion 41c to the end portion 41b.

<Second Embodiment>
Next, a second embodiment will be described. This embodiment is different from the first embodiment in that the insulating bag is changed to a bag shape by welding the end of one insulating sheet. In addition, about the same structure as the structure used in 1st embodiment, the drawing number similar to the drawing number used in 1st embodiment is used.

  FIGS. 7A to 7C show a detailed view of the conductive lead 41 and the insulating sheet 144 according to the second embodiment of the present invention and a view after assembly. Since FIG. 7A is the same as the conductive lead 41 of the first embodiment, the description is omitted. As shown in FIG. 7B, the insulating sheet 144 has two bent portions 144a1 and 144a2, and the end of the uppermost sheet folded after the conductive lead 41 is covered with the insulating sheet 144 is heated. The structure of this invention is realizable by fixing by methods, such as welding. FIG. 7C is a diagram after the conductive lead 41 is covered with the insulating sheet 144. The insulating sheet 144 is provided with an insulating sheet fixing portion 144b, and ends of the insulating sheet 144 are fixed by the insulating sheet fixing portion 144b to form an insulating bag 144c.

  In the insulating bag 44 of the first embodiment, since the conductive leads 41 must be passed through the insulating bag 44, the width of the insulating bag 44 is increased. When the width of the insulating bag 44 is increased, the insulating bag 44 may interfere with the insulating plate 34 when the lid unit 30 is assembled to the battery can 2, which may lead to a decrease in productivity and destruction of the insulating bag 44. is there.

  In the present invention, the insulating sheet 144c is formed by bending the insulating sheet 144 at two bent portions and disposing the insulating sheet fixing portion 144b in a portion facing the wide surface 41d of the conductive lead 41. By providing the insulating sheet fixing portion 144b at a position facing the wide surface 41d of the conductive lead 41, the width of the insulating bag 144c is equal to the width of the conductive lead 41 without the insulating sheet fixing portion 144c protruding from the conductive lead 41. Can be adjusted. Therefore, interference between the insulating bag 144c and the insulating plate 34 when the lid unit 30 is assembled to the battery can 2 can be prevented, and productivity and insulation reliability are improved.

  Note that an adhesive tape may be used as a method of fixing the insulating sheet 144, but thermal welding is preferable because flexibility is reduced by the thickness of the tape. In this case, the insulating bag 144 can be attached to the conductive lead 41 even after the normal assembly process of connecting the positive electrode current collecting ring 25 and the lid unit 30.

  By using a single insulating sheet 144 as in this embodiment, even if the width of the conductive lead is slightly changed due to dimensional tolerances, etc., it can be adjusted by the fixing width of the insulating sheet fixing portion 144b. It leads to improvement and yield improvement.

<Third embodiment>
Next, a third embodiment will be described. This embodiment is different from the second embodiment in that the bent portion of the insulating sheet is changed from two to one. In addition, about the same structure as the structure used by 2nd embodiment, the drawing number similar to the drawing number used by 2nd embodiment is used.

  FIGS. 8A to 8C show a detailed view and a view after assembly of the conductive lead 41 and the insulating sheet 244 according to the third embodiment of the present invention. Since FIG. 8A is the same as the conductive lead 41 of the first embodiment, the description is omitted. As shown in FIG. 8B, the insulating sheet 244 of the present embodiment has one bent portion 244a. The present invention can be realized by sandwiching the conductive lead 41 with the insulating sheet 244 and fixing its end by a method such as heat welding. FIG. 8C is a view after the conductive lead 41 is covered with the insulating sheet 144. The insulating sheet 244 is provided with an insulating sheet fixing portion 244b, and ends of the insulating sheet 244 are fixed by the insulating sheet fixing portion 244b to form an insulating bag 244c.

  In this embodiment, unlike the second embodiment, since the bent portion is one, the insulating sheet fixing portion 244b cannot be disposed on the wide surface 41d of the conductive lead 41. Therefore, as shown in FIG. 8C, an insulating sheet fixing portion 244b is provided at a position facing the side surface portion 41e of the conductive lead 41. As in the second embodiment, the insulating sheet 244 can be attached even after the normal assembly process.

  In the second embodiment, since there are two bent portions, if the accuracy of the second folding is poor, there is a possibility that the insulating sheet 144 is displaced and the insulating sheet is not sufficiently fixed. On the other hand, in the present embodiment, the possibility of misalignment caused by folding twice by making the bent part one place (because of two diffractions, the possibility of deviation is doubled) can be made only once. In addition, it is possible to suppress the shift when the end portion of the insulating sheet 244 is fixed, and the productivity is improved. In this embodiment, since the insulating sheet fixing portion 244b can be provided only at a position facing the side surface portion 41e of the conductive lead 41, the width of the insulating bag 244c is wider than that of the second embodiment. End up. Therefore, the second embodiment is more advantageous in terms of interference between the insulating bag and the insulating plate 34 when the lid unit 30 is assembled to the battery can 2.

  Moreover, since it can be said that it is common to 2nd embodiment and 3rd embodiment, since the insulating sheet adhering part is provided in 2nd embodiment and 3rd embodiment, the part which becomes hard in the state of an insulation bag is provided. Occur. Therefore, the first embodiment is more advantageous than the second embodiment and the third embodiment in terms of flexibility.

  The present invention has been summarized above. The cylindrical secondary battery according to the present invention includes a power generation element (10) in which a positive electrode (11) and a negative electrode (12) are wound around a shaft core (15) via a separator (13, 14). A current collecting ring (25) connected to the power generation element (10), a current collecting ring (25) connected to one end (41c), a conductive lead (41) made of a plurality of metal foils, and a conductive lead The other end (41b) of (41) has a connection plate (35) which is folded and connected. The conductive lead (41) is covered with insulating bags (44, 144c, 244c), and the conductive lead (41). ) And the insulating bag (44, 144c, 244c). By adopting such a structure, the flexible conductive lead and the flexible insulating bag are not fixed to each other, so that the flexibility of both the conductive lead and the insulating bag is not deteriorated. Therefore, since the risk of breaking the insulation between the conductive lead and other parts due to vibration or the like is reduced, the insulation reliability is improved.

  In the cylindrical secondary battery according to the present invention, the insulating bag (44, 144c, 244c) is made of an olefin resin, and the thickness of the insulating bag (44, 144c, 244c) is 0.02 mm or more and 0.50 mm. It is as follows. By adopting such a structure, it is possible to obtain a structure that does not impair flexibility while ensuring insulation.

The cylindrical secondary battery according to the present invention has a length L of the insulating bag (44, 144c, 244c) from one end (41c) where the conductive lead (41) is connected to the current collecting ring (25). The conductive lead (41) is connected to the connecting plate (35) from one end (41c) where the conductive lead (41) is larger than the length of the conductive lead (41) to the folded portion (41a) and connected to the current collecting ring (25). smaller length to the connected other end (41b). With such a structure, the folded portion of the conductive lead can be reliably protected with an insulating bag, and the insulation reliability is improved.

  Further, in the cylindrical secondary battery according to the present invention, the insulating bag (144c, 244c) is composed of one insulating sheet (144, 244), and the end portions of the insulating sheet (144, 244) are fixed to each other. It has an insulating sheet fixing part (144b, 244b). By adopting such a structure, it is possible to cope with any width of the conductive lead, which leads to an improvement in productivity and a yield.

  Further, in the cylindrical secondary battery according to the present invention, the conductive lead (41) has the wide surface (41d) and the side surface portion (41e), and the insulating sheet (144) is bent at two places, and the conductive lead ( The insulating sheet fixing part (144b) is disposed at a position facing the wide surface (41d) of 41). By adopting such a structure, the width of the insulating bag can be made substantially the width of the conductive lead. For this reason, when the lid unit is assembled to the battery can, the possibility that the insulating plate of the lid unit interferes with the insulating bag is reduced, and the productivity and the insulation reliability are improved.

  Further, in the cylindrical secondary battery according to the present invention, the conductive lead (41) has the wide surface (41d) and the side surface portion (41e), the insulating sheet (244) is bent at one place, and the conductive lead ( The insulating sheet fixing portion (244b) is disposed at a position facing the side surface portion (41e) of 41). By adopting such a structure, the insulating bag can be formed with one folding of the insulating sheet, so that the deviation caused by the folding can be reduced. Therefore, since the shift | offset | difference at the time of adhering an insulating sheet can be suppressed, productivity improves.

  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.

DESCRIPTION OF SYMBOLS 1 Cylindrical secondary battery 2 Battery can 2a Groove 2b Opening part 3 Battery cover 3a Peripheral part 3b Cylindrical part 3c Opening part 4 Battery container 5 Nonaqueous electrolyte 10 Power generation element 11 Positive electrode 11a Positive electrode metal foil 11b Positive electrode mixture layer 11c Positive foil exposed portion 12 Negative electrode 12a Negative metal foil 12b Negative electrode mixture layer 12c Negative foil exposed portion 13 First separator 14 Second separator 15 Axle core 15a Upper hollow portion 15b Step portion 16 Positive electrode tab 17 Negative electrode tab 19 Adhesive Tape 20 Power generation unit 21 Negative electrode current collector plate 21a Base portion 21b Open portion 21c Peripheral tube portion 21d Open portion 22 Holding member 25 Positive electrode current collector plate 25a Base portion 25b Lower tube portion 25c Upper tube portion 25d Open portion 25e Open portion 28 Holding member 30 Battery Lid unit 34 Insulating plate 34a Opening 34b Side 35 Connecting plate 35a Projection 35b Opening 37 Diaphragm 37a Notch 37b Side wall 41 Conductive lead 41a Folded portion 41b End portion 41c End portion 43 Gasket 43a Base portion 43b Outer peripheral wall portion 44 Insulating bag 50 Connection lead plate

Claims (6)

A power generating element in which a positive electrode and a negative electrode are wound around a shaft through a separator;
A current collecting ring connected to the power generation element;
One end of the current collector ring is connected, and a conductive lead made of a plurality of metal foils,
In the cylindrical secondary battery having a connection plate to which the other end of the conductive lead is folded and connected,
The conductive lead is covered with an insulating bag,
A cylindrical secondary battery having a gap between the conductive lead and the insulating bag. The cylindrical secondary battery according to claim 1,
The insulating bag is made of an olefin resin,
A cylindrical secondary battery, wherein the insulating bag has a thickness of 0.02 mm to 0.50 mm. The cylindrical secondary battery according to claim 1 or 2,
The length L of the insulating bag is greater than the length from one end where the conductive lead is connected to the current collecting ring to the folded portion of the conductive lead, and the conductive lead is connected to the connecting plate from one end where the conductive lead is connected to the current collecting ring. cylindrical secondary battery being less than the length to the connected other end. The cylindrical secondary battery according to any one of claims 1 to 3,
The said insulating bag consists of one sheet | seat, and has the insulating sheet fixed part to which the edge parts of the said insulating sheet were fixed, The cylindrical secondary battery characterized by the above-mentioned. The cylindrical secondary battery according to claim 4,
The conductive lead has a wide surface and a side surface,
2. The cylindrical secondary battery according to claim 1, wherein the insulating sheet is bent at two locations, and the insulating sheet fixing part is disposed at a position facing the wide surface of the conductive lead. The cylindrical secondary battery according to claim 4,
The conductive lead has a wide surface and a side surface,
The cylindrical secondary battery, wherein the insulating sheet is bent at one place, and the insulating sheet fixing portion is disposed at a position facing the side surface portion of the conductive lead.

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