JP2012234716A - Cylindrical secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent impairment of airtightness in a battery container due to waving occurred by swaging a battery lid and a lid member integrally.SOLUTION: A plurality of notches 55 are formed along an edge 52 on an upper end 51 that is bent toward an axis core side of a battery can 2. When the upper end 51 of the battery can 2 and a lid member 30 are swaged via a gasket 43, the upper end 51 of the battery can 2 is deformed so that a portion on an edge side of the notch 55 becomes narrow. As a result, the waving on the upper end 51 of the battery can 2 bent toward the axis core side is absorbed and the airtightness of the battery container is secured.

Description

  The present invention relates to a cylindrical secondary battery, and more particularly to a cylindrical secondary battery in which a battery can and a lid member that seals the battery can are fixed by caulking and the battery can is sealed from the outside.

A cylindrical secondary battery represented by a lithium ion secondary battery or the like contains a power generation element in which a positive electrode plate and a negative electrode plate are wound around a shaft core via a separator in a cylindrical battery container. The electrolyte is injected and configured.
The battery container includes a cylindrical battery can having an opening at the top, and a lid member that closes the upper opening of the battery can and is fixed to the battery can by caulking via an insulating member called a gasket.

  The battery can has a groove that is recessed toward the axial center on the peripheral wall near the opening, and is sealed through the following steps. A lid member is disposed on the groove that also receives the opening of the battery can with a ring-shaped insulating member interposed therebetween, and a portion on the upper side of the groove of the battery can is bent in a direction perpendicular to the cylindrical outer peripheral side surface. . Next, the bent portion of the battery can and the lid member are caulked with an insulating member interposed therebetween. In this way, a battery container sealed from the outside is formed (see, for example, Patent Document 1).

JP 2007-213819 A

  In the cylindrical secondary battery described in Patent Document 1, the battery can and the lid member are caulked through the above steps. That is, the peripheral edge side of the opening of the battery can is bent inward and caulked. Therefore, undulation occurs in the bent portion of the battery can. When undulation occurs in the caulking portion of the battery can, the pressure contact force between the insulating member and the lid member may vary, and airtightness may be impaired.

  The cylindrical secondary battery of the present invention has a power generating element in which a positive electrode plate and a negative electrode plate are wound around a shaft core via a separator, and a cylindrical shape in which an opening is formed on the upper side. A battery can in which a power generation element is housed and an electrolyte is injected, and a lid member that is fixed to the battery can by caulking via an insulating member and closes the opening of the battery can. The predetermined area is provided with a caulking portion that is bent inside the can so as to have a ring shape in plan view, and the caulking portion is formed with a plurality of notches in the circumferential direction from the inner edge toward the outer periphery of the battery can. It is characterized by being.

  According to the cylindrical secondary battery of the present invention, when the notch formed in the peripheral portion of the opening of the battery can is caulked, the opening is deformed so that the width on the opening side becomes smaller than the width on the outer peripheral side. As a result, the undulation at the peripheral edge of the opening of the battery can is alleviated, so that the airtightness of the cylindrical secondary battery can be ensured.

1 is a cross-sectional view of an embodiment of a cylindrical secondary battery according to the present invention. FIG. 2 is an exploded perspective view of the cylindrical secondary battery illustrated in FIG. 1. The perspective view of the state which showed the detail of the electric power generation element in the cylindrical secondary battery shown by FIG. 1, and cut | disconnected a part. The expanded sectional view which shows the fixation structure of the battery can shown in FIG. 1 and a cover member. FIG. 2 is an external perspective view of a lid member side in the cylindrical secondary battery illustrated in FIG. 1. The external appearance perspective view of the upper part side of a battery can before caulking to a lid member. FIG. 7 is an enlarged side view showing a shape of a notch in the battery can shown in FIG. 6. The front view of the upper part side of the battery can illustrated in FIG. The top view which shows a part of battery can in the state crimped to the cover member. It is a figure for demonstrating an example of the manufacturing method of a battery can, and is a perspective view of a battery can raw material. The perspective view for demonstrating the process following FIG. The perspective view for demonstrating the process following FIG. It is a figure for demonstrating the other manufacturing methods of a battery can, and is a perspective view which shows the process following FIG. The perspective view of the battery can for demonstrating the process following FIG. The side view of the battery can for demonstrating the process following FIG. The external appearance perspective view by the side of the cover member of the cylindrical secondary battery which shows Embodiment 2 of the cylindrical secondary battery of this invention. FIG. 17 is an external perspective view showing one state in a manufacturing process of the battery can illustrated in FIG. 16. FIG. 17 is an enlarged side view showing a shape of a notch in the battery can shown in FIG. 16. The side view of the upper part side of a battery can before caulking to a lid member. The top view which shows a part of the upper part side of the battery can of the state crimped to the cover member. FIG. 17 is a perspective view for explaining a manufacturing method of the cylindrical secondary battery of Embodiment 2 illustrated in FIG. 16. The perspective view of the battery can raw material for demonstrating the other preparation methods of the cylindrical secondary battery of Embodiment 2 illustrated in FIG.

(Embodiment 1)
[Overall structure of cylindrical secondary battery]
Hereinafter, an embodiment of a cylindrical secondary battery of the present invention will be described with reference to the drawings.
FIG. 1 is an enlarged cross-sectional view showing an embodiment of a cylindrical secondary battery of the present invention, and FIG. 2 is an exploded perspective view of the cylindrical secondary battery shown in FIG.
The cylindrical secondary battery 1 is, for example, a lithium ion secondary battery, and has a bottom portion 2c and a cylindrical battery can 2 having an opening 2b at the top, and a hat type that seals the opening 2b of the battery can 2. A battery container composed of the battery lid 3. Inside the battery container, each component for power generation described below is accommodated, and a non-aqueous electrolyte 5 is injected.

The cylindrical battery can 2 is made of, for example, iron (SPCC), and nickel plating is applied to both the inner and outer surfaces. In the 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 disposed at the center of 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 plate and a negative electrode plate wound around the shaft core 15 via a separator.

  The shaft core 15 has a hollow cylindrical shape having a hollow portion formed along the axis. A groove 15a having a diameter larger than that of the hollow portion is formed on the inner surface of the upper end portion of the shaft core 15 in the axial direction (vertical direction in the drawing).

[Power generation element]
FIG. 3 is a perspective view showing the details of the structure of the power generation element 10, with a part cut away.
As shown in FIG. 3, the power generation element 10 has a structure in which a positive electrode plate 11, a negative electrode plate 12, and first and second separators 13 and 14 are wound around an axis 15.

  The shaft core 15 is formed of, for example, PP (polypropylene), and has a hollow cylindrical shape having a hollow portion formed along the axis. A first separator 13, a negative electrode plate 12, a second separator 14, and a positive electrode plate 11 are sequentially stacked on the shaft core 15 and wound. Although not shown in FIG. 3, the first separator 13 and the second separator 14 are wound several times inside the innermost negative electrode plate 12.

  On the inner circumference (axial core) side, the negative electrode plate 12 extends from the positive electrode plate 11 to the axial core side. On the outer peripheral side, the negative electrode plate 12 extends to the outer peripheral side from the positive electrode plate 11. A second separator 14 extends on the outer periphery of the outermost negative electrode plate 12. The second separator 14 at the outermost periphery is stopped with an adhesive tape 19 formed of PP or the like (see FIG. 2).

  The positive electrode plate 11 is formed of an aluminum foil and has a long shape. The positive electrode plate 11 includes a positive electrode metal foil 11a and a positive electrode processing portion 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 mixture untreated portion 11c where the positive electrode mixture is not applied and the positive electrode metal foil 11a is exposed. In the positive electrode mixture untreated portion 11c, a large number of positive electrode leads 16 protruding upward along the axis of the shaft core 15 are integrally formed at equal intervals.

The positive electrode mixture includes a positive electrode active material such as lithium oxide, a positive electrode conductive material, and a positive electrode binder formed of polyvinylidene fluoride (PVDF) or the like.
The positive electrode mixture is applied to both sides of the positive electrode metal foil 11a made of an aluminum foil having a thickness of about 20 μm so as to have a thickness of about 40 μm on one side. When cutting the positive electrode metal foil 11a, the positive electrode lead 16 is integrally formed.

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

The negative electrode mixture is composed of a negative electrode active material such as graphite carbon, a negative electrode binder, and a thickener.
The negative electrode mixture is applied to both sides of a negative electrode metal foil 12a made of a rolled copper foil having a thickness of about 10 μm so as to have a thickness of about 40 μm on one side. When the negative electrode metal foil 12a is cut by pressing, the negative electrode lead 17 is integrally formed.

The widths of the first and second separators 13 and 14 are larger than the widths of the positive electrode plate 11 and the negative electrode plate 12.
The width of the negative electrode processing part 12 b of the negative electrode plate 12 is larger than the width of the positive electrode processing part 11 b of the positive electrode plate 11. The width and length of the negative electrode processing unit 12b are made larger than the width and length of the positive electrode processing unit 11b, and the entire region of the positive electrode processing unit 11b is covered with the negative electrode processing unit 12b. In the case of a lithium ion secondary battery, if the negative electrode active material is not formed on the negative electrode side and the negative electrode metal foil 12a is exposed, the lithium ions on the positive electrode side are deposited on the negative electrode metal foil 12a and cause an internal short circuit It becomes. As described above, by covering the entire region of the positive electrode processing unit 11b with the negative electrode processing unit 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 about 40 μm.

[Power generation unit]
In FIG. 1, a hollow cylindrical shaft core 15 is provided with a groove 15a having a diameter larger than that of the hollow portion on the inner surface of the upper end portion in the axial direction (vertical direction in the drawing). The positive electrode current collector plate 27 is press-fitted.

The positive electrode current collector plate 27 is made of, for example, an aluminum metal.
The positive electrode current collecting plate 27 protrudes toward the shaft core 15 at the disc-shaped base portion 27a, the inner peripheral portion of the base portion 27a, and is pressed into the inner surface of the shaft core 15, and the battery lid 3 at the outer peripheral edge. It has the upper cylinder part 27c which protrudes to the side. An opening 27d (see FIG. 2) for releasing gas generated inside the battery is formed in the base 27a of the positive electrode current collector plate 27.

  The positive electrode lead 16 and the pressing member 28 of the positive electrode metal foil 11 a are joined to the outer periphery of the upper cylindrical portion 27 c of the positive electrode current collector plate 27. A number of positive leads 16 are brought into close contact with the outer periphery of the upper cylindrical portion 27c of the positive current collector plate 27, and a pressing member 28 is wound around the outer periphery of the positive lead 16 in a ring shape and temporarily fixed. Joined by welding.

  A negative electrode current collector plate 21 is press-fitted and attached to the lower end portion of the shaft core 15. The negative electrode current collector plate 21 is made of, for example, copper, 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 out is formed.

The negative electrode lead 17 and the pressing member 22 of the negative electrode metal foil 12 a are joined to the outer periphery of the outer peripheral cylindrical portion 21 c of the negative electrode current collector plate 21. A number of negative electrode leads 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 lead 17 in a ring shape and temporarily fixed. In this state, ultrasonic welding is performed. Are joined together.
A negative electrode conducting lead 23 made of nickel is welded to the lower surface of the negative electrode current collecting plate 21. The negative electrode conducting lead 23 is welded to the battery can 2 at the bottom 2 c of the iron battery can 2.

  The positive electrode current collector plate 27 is formed with an opening 27 e (see FIG. 2) for inserting an electrode rod for welding the negative electrode energizing lead 23 to the battery can 2. An electrode rod (not shown) is inserted into the hollow portion of the shaft core 15 through the opening 27e formed in the positive electrode current collector plate 27, and the negative electrode energizing lead 23 is pressed against the inner surface of the bottom 2c of the battery can 2 at the tip. Resistance welding is performed. The bottom 2c of the battery can 2 connected to the negative electrode current collector plate 21 is used as one output terminal.

  A large number of positive electrode leads 16 are welded to the positive electrode current collector plate 27, and a large number of negative electrode leads 17 are welded to the negative electrode current collector plate 21, whereby the positive electrode current collector plate 27, the negative electrode current collector plate 21 and the power generation element 10 are integrated. A unitized power generation unit 20 is configured (see FIG. 2). However, in FIG. 2, for convenience of illustration, the negative electrode current collector plate 21, the pressing member 22, and the negative electrode conducting lead 23 are illustrated separately from the power generation unit 20.

  On the upper surface of the base portion 27a of the positive electrode current collector plate 27, a flexible connection lead 33 constituted by laminating a plurality of aluminum foils is joined by welding one end thereof. The connection lead 33 can flow a large current by laminating and integrating a plurality of aluminum foils, and is provided with flexibility.

[Battery cover unit]
A battery lid unit 40 is disposed on the upper cylindrical portion 27 c of the positive electrode current collector plate 27. The battery lid unit 40 includes a ring-shaped insulating plate 34, a connection plate 35 fitted in an opening 34 a (see FIG. 2) provided in the insulating plate 34, and a diaphragm structure lid 37 welded to the connection plate 35. The battery lid 3 is fixed to the lid 37 by caulking.

The insulating plate 34 is made of, for example, an insulating resin material such as PP, has a ring shape having a circular opening 34 a, and is placed on the upper cylindrical portion 27 c of the positive electrode current collector plate 27.
The insulating plate 34 has a cylindrical portion 34b that extends downward and protrudes toward the opening. A connecting plate 35 is fitted to the cylindrical portion 34 b of the insulating plate 34. The other end of the connection lead 33 is joined to the lower surface of the connection plate 35 by laser welding or the like. The connection lead 33 is folded back at the other end side, and the same surface as the surface welded to the positive electrode current collector plate 27 is joined to the connection plate 35.

  The connection plate 35 is made of an aluminum-based metal, is substantially uniform except for the central portion, and has a substantially disk shape. A protrusion 35a is formed at the center of the connection plate 35, and is joined to the bottom surface of the center of the lid 37 by resistance welding or friction stir welding. The lid body 37 is made of an aluminum-based metal, and has a circular cut 37b (see FIG. 2) in a base portion 37a of the lid body 37. The notch 37b is formed by crushing the upper surface side into a V shape by pressing and thinning the remaining portion. The lid 37 is provided for ensuring the safety of the battery, and when the internal pressure of the battery rises, the lid 37 warps upward and cleaves from the notch 37b as a starting point to release the gas inside the battery.

  The lid 37 is fixed by caulking to the peripheral edge 3a of the battery lid 3 at the flange 37c (see FIG. 1). A method for caulking the lid 37 and the battery lid 3 will be described later. Before the caulking, the flange 37c of the lid 37 is raised substantially perpendicular to the base portion 37a as shown in FIG. ing. The lid body 37 is formed with four welding projections 37d. Similarly to the flange 37c, the welding projection 37d is also raised substantially perpendicular to the base portion 37a before the caulking.

  The battery lid 3 is formed of a cold rolled steel plate (SPCC), and nickel plating is applied to both the inside and outside. The battery lid 3 has a hat shape having a disc-shaped peripheral edge portion 3a caulked on the lid body 37 and a cylindrical portion 3b protruding upward from the peripheral edge portion 3a.

[Battery container sealing structure]
Referring to FIG. 1, a ring-shaped gasket 43 is provided on the outer periphery of the flange portion 37 b of the lid body 37. The gasket 43 is made of, for example, perfluoroalkoxy fluororesin (PFA). As shown in FIG. 2, the gasket 43 initially has a peripheral portion 43 b that rises perpendicular to the base portion 43 a.

FIG. 4 is an enlarged cross-sectional view illustrating a fixing structure between the battery can and the lid member illustrated in FIG. 1.
The peripheral edge of the opening 2b of the battery can 2 and the lid member 30 are fixed by caulking with a gasket 43 interposed therebetween.

A method for caulking the peripheral edge of the opening 2b of the battery can 2 and the lid member 30 will be described.
The gasket 43 is placed on the upper part of the groove 2 a of the battery can 2, and the lid member 30 is accommodated in the opening of the gasket 43. As described above, in this state, as shown in FIG. 2, the peripheral portion 43b of the outer peripheral portion of the base portion 43a rises in the vertical direction with respect to the base portion 43a.
A portion on the upper side of the groove 2a of the battery can 2 is bent at a substantially right angle from the outer periphery of the cylindrical shape toward the axis. For this purpose, the inclined portion of the pressing jig is brought into contact with the peripheral portion of the opening 2b of the battery can 2 and the peripheral portion of the opening 2b of the battery can 2 is once bent in an inclined manner. Next, using a flat pressing jig, the peripheral edge of the opening 2b of the battery can 2 is bent toward the groove 2a of the battery can 2 with the gasket 43 interposed therebetween. Thereby, the peripheral edge of the opening 2 b of the battery can 2 and the peripheral edge of the lid member 30 are bent and fixed via the peripheral edge 43 b of the gasket 43. Thus, the peripheral edge of the opening 2b of the battery can 2, the peripheral edge 43b of the gasket 43, and the peripheral edge of the lid member 30 are caulked and integrated.

  In the above, the lid member 30 is integrated in advance by caulking the peripheral edge portion 3 a of the battery lid 3 and the flange portion 37 c of the lid body 37. The method for caulking the battery can 2 and the lid member 30 is the same as the method for caulking the battery lid 3 and the lid 37. Prior to caulking, as shown in FIG. 2, the lid 37 has a flange 37 c and a welding projection 37 d erected substantially perpendicular to the base 37 a. The battery lid 3 is disposed inside the flange 37c, and the battery lid 3 is caulked by bending the flange 37c of the lid body 37 and the welding projection 37d toward the axial center side. For this purpose, as in the case where the battery can 2 and the lid member 30 are caulked, the flange 37c and the welding projection 37d of the lid 37 are bent at one end in an inclined manner by pressing, and then axially Bend to. After caulking the flange 37c and the welding protrusion 37d of the lid 37 to the peripheral edge 3a of the battery lid 3, the welding protrusion 37d of the lid 37 is connected to the peripheral edge 3a of the battery lid 3 by resistance welding or friction sales expansion joining. Join by etc.

  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 solvent can be cited.

[Structure of lid member]
5 is an external perspective view of the lid member side of the cylindrical secondary battery illustrated in FIG.
As described above, the peripheral edge portion of the opening 2b of the battery can 2 is bent from the cylindrical outer peripheral portion toward the axial core, and is caulked to the peripheral edge portion of the lid member 30 with the peripheral edge portion 43b of the gasket 43 interposed therebetween. The member 30 is integrated with the battery can 2.

FIG. 6 is an external perspective view of the upper side of the battery can 2 before caulking to the lid member 30. 7 is an enlarged side view showing the shape of the notch of the battery can 2 shown in FIG. 6, and FIG. 8 is a front view of the upper side of the battery can 2 shown in FIG.
As shown in FIGS. 6 and 8, the notches 55 of the battery can 2 are substantially equidistant along the peripheral edge of the opening 2 b in the region of the upper end 51 of the battery can 2 before caulking. Is formed. As shown in FIG. 7, each notch 55 is formed in a U-shape having a semicircular arc-shaped end 55 a. The width of the notch 55 is substantially uniform except for one end 55a. Each notch 55 has one end 55 a located inside the upper end 51 and the other end opened to the edge 52 of the upper end 51. In other words, the other end of the notch 55 communicates with the opening 2 b of the battery can 2.

FIG. 9 is a plan view showing a part of the battery can 2 in a state crimped to the lid member 30.
The notch 55 formed in the upper end 51 of the battery can 2 has a substantially uniform width before caulking, but after caulking, the notch 55 is narrower on the edge 52 side than the one end 55a side. . Or it is obstruct | occluded in the edge part 52 side.

When the opening 2b side of the battery can 2 is bent into the can, the edge 52 side of the upper end 51 becomes the inner diameter side of the circle with respect to the outer periphery of the cylindrical battery can 2 in plan view. That is, by bending the upper end 51 bent in a link shape in plan view, the edge 52 side of the upper end 51 is equal to the difference between the circumference of the outer circumference and the circumference of the inner circumference. The length of the circumference is left. For this reason, when using the battery can without the notch 55 which is a prior art, the upper end 51 of the battery can 2 is deformed and becomes wavy.
If the battery can 2 is undulating at the peripheral edge, a gap is formed between the peripheral edge of the battery can 2 and the peripheral edge 43b of the gasket 43, so that the airtightness of the cylindrical secondary battery 1 may be impaired. .

  However, in the cylindrical secondary battery 1 according to the present embodiment, a plurality of notches 55 extending from the edge 52 toward the outer peripheral side of the battery can 2 are formed at the upper end 51 of the battery can 2. ing. During caulking, the upper end 51 of the battery can 2 is deformed so that the notch 55 becomes narrower on the edge 52 side, and the outer circumference and inner circumference of the phosphorus-like upper end 51 are viewed in plan view. The difference between the circumference and the circumference is absorbed. Thus, the undulation of the upper end 51 of the battery can 2 is suppressed. For this reason, in this embodiment, the space | gap resulting from a wave is suppressed between the upper side edge part 51 of the battery can 2, and the gasket 43, and the airtightness of the cylindrical secondary battery 1 improves.

  In order to completely absorb the difference in length between the outer periphery and the inner periphery of the upper end 51 of the battery can 2, the width of the notch 55 is the sum of the outer periphery and the inner periphery. It is preferable to make it equal to or larger than the difference in circumference. However, if the notch 55 is formed, the degree of undulation is reduced by that amount. Therefore, the total width of the notch 55 is the difference between the circumference of the outer circumference and the inner circumference. It can be smaller than the difference.

[Production Method 1 of Battery Container]
Next, a method for producing a battery container in which the battery can 2 is integrated with the lid member 30 by caulking and sealed from the outside will be described with reference to FIGS.
First, as illustrated in FIG. 10, a cold-rolled steel plate (SPCC) is cut into a circle by pressing to produce a battery can material 2 ′.
Next, the battery can material 2 ′ is drawn to form a cylindrical tube having a bottom 2c and an opening 2b at the top, as shown in FIG.

Next, the battery can material 2 ′ in the state shown in FIG. 11 is processed using the punch 60 to form a notch 55 at the peripheral edge of the opening 2b on the upper side.
As shown in FIG. 12, the punch 60 has a front surface portion 61 formed in an arc shape having the same radius as the outer peripheral surface of the battery can 2. A plurality of U-shaped protrusions 62 corresponding to the notches 55 formed in the battery can 2 are formed on the bottom of the punch 60.
The distance between the protrusions 62 is substantially the same along the circumference. In other words, the linear interval in the width direction is an interval obtained by projecting the notches 55 arranged at equal intervals along the circumference on a plane.

Although not shown, a cylindrical die having an outer diameter whose outer surface is in contact with the inner surface of the battery can material 2 ′ is inserted inside the cylindrical battery can material 2 ′. In the die, slits corresponding to the protrusions 62 of the punch 60 are formed.
The punch 60 is aligned with the slit of the die, and the battery can blank 2 'is punched. At the time of punching, the punch 60 is moved in the direction of the arrow in FIG. 12 with the orientation of the punch 60 aligned so that the central axis in the width direction passes through the axis of the battery can material 2 ′. As a result, the number of notches 55 corresponding to the protrusions 62 of the punch 60 is formed in the battery can material 2 ′.

Next, the battery can blank 2 'is rotated by a predetermined angle, the area to be punched is determined, and the punching process is performed by the punch 60, whereby the notch 55 is formed in the processed area. By performing rotation indexing and punching of the battery can material 2 ′ a plurality of times, a notch 55 is formed around the entire periphery of the opening 2b of the battery can material 2 ′ as shown in FIG.
In FIG. 12, for convenience of explanation, the battery can material 2 ′ shows a state in which the punching process using the punch 60 has been completed and the cutout 55 has been formed on the entire circumference on the upper end 51 side.

After the notch 55 is formed around the entire periphery of the opening 2b of the battery can material 2 ′, the battery can material 2 ′ and the lid member 30 are caulked with the gasket 43 interposed therebetween.
First, a groove 2a (see FIGS. 1 and 5) is formed on the outer periphery in the vicinity of the opening 2b of the battery can material 2 ′ in the state shown in FIG.
Then, as described above, a predetermined region on the upper side from the groove 2a of the battery can 2, that is, the upper end portion 51 is bent substantially at a right angle toward the inside of the tube. To this end, the upper end 51 of the battery can 2 is inclined toward the axis, and then the upper end 51 is bent toward the groove 2a of the battery can 2 with the gasket 43 interposed therebetween. Press contact with the periphery. As a result, the upper end 51 of the battery can 2, the peripheral edge 43b of the gasket 43 and the peripheral edge of the lid member 30 are caulked and integrated to form a battery container that is sealed to the outside. Before the battery can 2 and the lid member 30 are crimped, the power generation unit 20 is accommodated in the battery can 2 and the nonaqueous electrolyte solution 5 is injected, whereby the cylindrical secondary battery 1 is manufactured.

  In the said embodiment, the space | interval of the projection part 62 formed in the punch 60 was illustrated as the length along a circumference is equal intervals. However, the interval between the notches 55 does not have to be exceptionally accurate, and the interval between the protrusions 62 of the punch 60 may be linearly equal. In other words, the intervals in the width direction of the punch 60 may be the same.

In the said embodiment, the front part 61 of the punch 60 is formed in the circular arc shape of substantially the same radius as the outer periphery of battery can raw material 2 '. For this reason, the front surface portion 61 of the punch 60 is uniformly in contact with the outer periphery of the battery can blank 2 ′, the shape of the notch 55 becomes uniform, and the deformation of the battery can blank 2 ′ can be eliminated.
However, the shape of the notch 55 does not have to be exceptional and accurate, and the front surface portion 61 of the punch 60 may be flat.

[Battery container manufacturing method 2]
Next, another example of the battery container manufacturing method will be described with reference to FIGS.
FIG. 13 is a diagram for explaining another method for manufacturing the battery can, and shows a step subsequent to FIG. 10. 14 is a perspective view of the battery can for explaining the process following FIG. 13, and FIG. 15 is a side view of the battery can for explaining the process following FIG.
First, as illustrated in FIG. 10, a cold-rolled steel plate (SPCC) is cut into a circle by pressing to produce a flat battery can material 2 ′.
Next, as illustrated in FIG. 13, a notch 55 is formed in the vicinity of the outer peripheral edge of the battery can material 2 ′.

  The U-shaped cutout 55 is formed so as to be disposed in the region of the upper end 51 shown by a two-dot chain line in FIG. In FIG. 13, the other end of the U-shaped cutout 55 extends to the edge portion 52 indicated by a two-dot chain line, and the semicircular one end 55 a is formed to be positioned inside the edge portion 52.

  Next, as shown in FIG. 14, the battery can material 2 ′ is drawn to form a cylindrical portion having a bottom portion 2 c at the center of the flat portion 58. Drawing is performed in several steps, and the height of the cylindrical portion is gradually increased.

Then, as shown in FIG. 15, the drawing is performed to a position where the edge 52 of the upper end 51 becomes the boundary between the cylindrical portion and the flat portion 58.
In this state, the other end portion of the notch 55 is located at the flat portion 58 or the edge portion 52.
Here, when the flat portion 58 protruding on the outer periphery of the cylindrical portion is cut at the position of the outer peripheral side surface of the cylindrical portion, the battery can material 2 ′ is cut out over the entire periphery of the upper end 51 shown in FIG. 12. A cylindrical body having a bottom 2c in which 55 is arranged.
The following is a battery container sealed from the outside, in which the upper end 51 of the battery can 2 and the lid member 30 are caulked with a gasket 43 by the same method as described in the battery container manufacturing method 1. Can be produced.

[Effect of Embodiment 1]
In the above-described embodiment, the plurality of notches 55 are formed in the upper end portion 51 of the battery can 2 that is bent toward the inner peripheral side when the lid member 30 is fixed by caulking. During caulking, the upper end 51 of the battery can 2 is deformed so that the edge 52 side of the notch 55 becomes narrow. Along with this, undulation is absorbed or reduced in the upper end 51 of the battery can 2 bent toward the inner peripheral side. For this reason, the clearance resulting from the corrugation of the battery can 2 does not occur between the battery can 2 and the gasket 43, and the airtightness of the cylindrical secondary battery 1 is improved.

(Embodiment 2)
FIG. 16 is a perspective view of the appearance of the cylindrical secondary battery according to the second embodiment of the present invention, and is an external perspective view of the cylindrical secondary battery on the lid member side, and FIG. 1 is an external perspective view showing the upper side of the battery can before it is caulked on the lid member. FIG. 18 is an enlarged side view showing the notch shape of the battery can shown in FIG.
The lid member 30 shown in the second embodiment is different from the first embodiment in that the shape of the notch 55 ′ formed in the upper end 51 of the battery can 2 before caulking is V as shown in FIG. It is the point made the character shape.
Others are the same as those of the first embodiment, and the corresponding members are denoted by the same reference numerals and description thereof is omitted.

As illustrated in FIG. 18, the cutout 55 ′ formed in the upper end 51 of the battery can 2 is formed in a V shape in which one end 55 a is sharp.
FIG. 20 is a plan view showing a part of the upper side of the battery can in a state crimped to the lid member.
Prior to caulking, the width of the notch 55 ′ formed in the upper end 51 of the battery can 2 increases linearly from the one end 55 a toward the edge 52. For this reason, the width of the notch 55 ′ after caulking is substantially uniform over the entire length. If the width on the edge 52 side of the cutout 55 ′ is appropriate, the width of the cutout 55 ′ after caulking can be made almost zero over the entire length of the cutout 55 ′.
Other configurations in the second embodiment are the same as those in the first embodiment, and corresponding members are denoted by the same reference numerals and description thereof is omitted.

FIG. 21 is a diagram for explaining a first method for producing the battery can 2 shown in the second embodiment.
This method is basically the same as the manufacturing method 1 of the battery can 2 described in regard to the first embodiment.
As shown in FIG. 10, a circular battery can material 2 ′ is cut out and the battery can material 2 ′ is drawn to produce a cylindrical tube having a bottom 2c as shown in FIG. .

Then, the cylindrical battery can material 2 ′ illustrated in FIG. 11 is processed using the punch 60 to form the battery can 2.
The protrusion 62 ′ formed on the bottom of the punch 60 is different from the method 1 for producing the battery can material 2 ′ in Embodiment 1 in that the protrusion 62 ′ has a V shape as illustrated in FIG. 21. It is.

FIG. 22 is a view for explaining a second method of manufacturing the battery can 2 shown in the second embodiment.
This method is basically the same as the battery container manufacturing method 2 described in connection with the first embodiment.
As shown in FIG. 10, a circular battery can material 2 ′ is cut out, and as shown in FIG. 22, a cutout 55 ′ is formed in the vicinity of the outer peripheral edge of the battery can material 2 ′.
The point that the notch 55 ′ formed in the battery can material 2 ′ has a V-shape is different from the battery container manufacturing method 2 of the first embodiment.

  Thereafter, as in the case of the first embodiment, the battery can material 2 ′ is made into a cylindrical portion up to the edge portion 52 by drawing (see FIG. 15), and the flat portion 58 is cut, thereby forming the notch 55 ′. A cylindrical body having the other end as a tip is formed (see battery can material 2 ′ in FIG. 12). Then, as described above, a battery container is produced by caulking the battery can material 2 ′ and the lid member 30 with the gasket 43 interposed therebetween. Before the battery can 2 and the lid member 30 are crimped, the power generation unit 20 is accommodated in the battery can 2 and the nonaqueous electrolyte solution 5 is injected, whereby the cylindrical secondary battery 1 is manufactured.

[Effect of the embodiment]
Also in the second embodiment, since the plurality of cutouts 55 ′ are formed in the upper end portion 51 of the battery can 2, the upper end portion 51 of the battery can 2 is wide at the edge 52 side of the cutout 55 ′ when caulking. It deform | transforms so that it may become narrow, and the difference of the circumference of the circumference of the outer periphery of the upper side edge part 51 and the circumference of an inner periphery is absorbed. For this reason, there is no gap due to the undulation of the battery can 2 between the battery can 2 and the gasket 43, and the airtightness of the cylindrical secondary battery 1 is improved.

  In the second embodiment, the notch 55 ′ formed in the upper end 51 of the battery can 2 before caulking is formed into a V shape that becomes wider from the one end 55 a toward the inner peripheral edge 52. Yes. For this reason, after caulking, the width of the notch 55 becomes a uniform width almost close to 0, and the caulking strength can be made almost uniform over the entire circumference.

  In the first and second embodiments, the shape of the notches 55 and 55 ′ formed in the battery can 2 is exemplified as a U shape or a V shape, but is not limited to this shape. The shape of the notches 55 and 55 'may be, for example, a rectangular shape, an elliptical shape, an inverted trapezoidal shape, or a combined shape obtained by combining these shapes.

  The notches 55 and 55 'formed at the peripheral edge of the opening 2b of the battery can need not be equally spaced. Further, the notches 55 and 55 'are not limited to the structure formed over the entire periphery, and may be formed only in a part of the region.

  In the said embodiment, the battery cover unit 40 was illustrated as what was comprised by the battery cover 3, the cover body 37, the insulating board 34, and the connection board. However, the battery lid unit 40 is not limited to the above configuration, and the present invention can be applied to the battery lid unit 40 to which other components are added or which do not have a part of the components. It is.

  In the above-described embodiment, the lid member 30 is exemplified as being configured by the battery lid 3 serving as one external electrode terminal and the lid body 37 having a diaphragm structure. However, the present invention is not limited to the structure in which the battery lid 3 and the lid body 37 are integrated by caulking, but can be widely applied to a lid member constituted by one member.

  In the said embodiment, the case of the lithium ion cylindrical secondary battery was demonstrated. However, the present invention can also be applied to a cylindrical secondary battery using a water-soluble electrolyte such as a nickel metal hydride battery, a nickel cadmium battery, or a lead storage battery. The present invention can also be applied to a cylindrical lithium ion capacitor.

  In addition, the cylindrical secondary battery of the present invention can be applied in various modifications within the scope of the invention. In short, the positive electrode plate and the negative electrode plate have a shaft core through a separator. A power generation element wound around, a cylindrical shape having an opening formed on the upper side, a power generation element accommodated therein, and an electrolyte injected therein, and a battery can through an insulating member A lid member that is fixed by caulking and closes the opening of the battery can, and a predetermined area of the opening of the battery can is provided with a caulking portion that is bent inside the can so as to form a ring shape in plan view. The caulking portion only needs to have a plurality of notches formed in the circumferential direction from the inner edge toward the outer periphery of the battery can.

DESCRIPTION OF SYMBOLS 1 Cylindrical secondary battery 2 Battery can 3 Battery cover 10 Power generation element 11 Positive electrode plate 12 Negative electrode plate 20 Power generation unit 30 Cover member 40 Battery cover unit 43 Gasket (insulation member)
51 Upper end 52 Edge 55, 55 ′ Notch 55a One end

Claims (6)

A power generation element in which a positive electrode plate and a negative electrode plate are wound around a shaft core via a separator;
A battery can having a cylindrical shape with an opening formed on the upper side, containing the power generation element therein, and injected with an electrolyte, and
A lid member fixed by caulking to the battery can via an insulating member and closing the opening of the battery can;
A predetermined area of the opening of the battery can is provided with a crimped portion bent inside the can so as to have a ring shape in plan view,
A cylindrical secondary battery in which a plurality of notches are formed in the caulking portion in the circumferential direction from the inner edge toward the outer periphery of the battery can.   2. The cylindrical secondary battery according to claim 1, wherein the notches of the battery can are each formed in a U shape.   2. The cylindrical secondary battery according to claim 1, wherein the notches of the battery can are each formed in a V shape.   The cylindrical secondary battery according to any one of claims 1 to 3, wherein a total value of the circumferential widths of the plurality of notches is a circumferential length of an inner edge of the caulking portion of the ring shape, A cylindrical secondary battery characterized in that it is equal to or larger than the difference between the outer circumference of the battery can.   5. The cylindrical secondary battery according to claim 1, wherein the circumferential width of the notch is such that the inner edge side of the caulking portion of the ring shape is closer to the peripheral surface side of the battery can. Cylindrical secondary battery characterized by being large.   The cylindrical secondary battery according to any one of claims 1 to 5, wherein a groove is provided on the opening side of the battery can so as to be recessed on the inner side of the can at the bottom side of the can than the caulking portion. The upper end of the battery can is bent between the groove and the opening of the battery can in the axial direction from the outer peripheral side surface of the battery can and presses the lid member through the insulating member. One end of the notch is formed in a region of the upper end portion.

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