JP2014103026A - Storage element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit the corrosion of a plastically deformed portion of a metal member having a plated layer in a secondary battery or a capacitor.SOLUTION: A secondary battery 1 is provided with a battery container 4. The battery container 4 has a power generation unit 20 accommodated inside a battery can 2 on the outer surface of which is formed a plated layer 2p. The battery container 4 has an electrolyte solution injected therein. The battery can 2 has a groove 201 and a constricted part 203 which are plastically deformed portions formed by fabrication work. On the plated layer 2p formed on the outer surface of such a plastically deformed portion is provided a coating layer M containing a corrosion-inhibiting metal material which has a larger ionization tendency than the metal member of the battery can 2.

Description

  The present invention relates to a power storage device, and more particularly to a power storage device including a container in which a plastically deformed portion is formed.

In a cylindrical secondary battery typified by a lithium secondary battery or the like, a battery can in which a power generation unit having a wound body in which a positive electrode and a negative electrode are wound is accommodated and an electrolyte is injected, and a battery A battery lid is provided to seal the can.
The battery can is formed in a bottomed cylindrical shape, and a plating layer such as nickel is formed on the inner and outer surfaces thereof.
The battery can is connected to one electrode of the power generation unit, for example, the positive electrode, and functions as one external electrode terminal. The battery lid is connected to the other electrode of the power generation unit, for example, the negative electrode, and functions as the other external electrode terminal.

The battery can and the battery lid constitute a highly reliable sealing structure with respect to the outside. The following structure is known as an example of the sealing structure of the battery can and the battery lid.
A groove having a U-shaped cross section narrowed from the outer peripheral side toward the inner peripheral side is formed on the open end side of the bottomed cylindrical battery can, and a gasket and a battery lid are stacked and placed on the groove. The peripheral edge of the battery lid placed in the groove shape is fixed to the battery can by caulking through a gasket by bending the opening edge of the battery can at a substantially right angle (see, for example, Patent Document 1). ).

JP 2011-187337 A

In order to caulk the battery lid and the battery can, it is necessary to form a groove having a U-shaped cross section or a plastically deformed portion such as a bent portion that is bent substantially at right angles as described above. The groove is formed by, for example, grooving, and the bent portion is formed by, for example, pressing. For this reason, the plating layer formed on the surface of the battery can may be cracked by the process of forming the plastic deformation portion.
If cracks occur in the plating layer, the battery can may be corroded due to changes over time.

  The electricity storage device of the present invention includes a metal member having a plating layer formed on the outer surface, a power generation unit accommodated therein, and a container into which an electrolytic solution is injected. This container has a plastically deformed portion formed by processing, and a coating layer containing a corrosion-inhibiting metal material having a higher ionization tendency than a metal member is formed on the plating layer formed on the outer surface of the plastically deformed portion. Is provided.

  According to the present invention, the coating layer containing the corrosion-inhibiting metal material having a higher ionization tendency than the metal member is provided on the plating layer formed on the outer surface of the plastic deformation portion. Corrosion can be suppressed.

Sectional drawing of the lithium ion cylindrical secondary battery as one Embodiment of the electrical storage element of this invention. FIG. 2 is an exploded perspective view of the cylindrical secondary battery illustrated in FIG. 1. The perspective view of the state which cut | disconnected a part for showing the detail of the electrode group illustrated by FIG. The expanded sectional view of the area | region A of the battery can illustrated in FIG. 2 is a flowchart illustrating a method for manufacturing the cylindrical secondary battery illustrated in FIG. 1. The perspective view for showing the method of producing a battery can. The perspective view for demonstrating the process following FIG. FIG. 8 is an enlarged cross-sectional view for explaining a process following FIG. 7. The expanded sectional view for demonstrating the process shown in FIG. FIG. 10 is an enlarged cross-sectional view for explaining a process following FIG. 9. FIG. 11 is an enlarged cross-sectional view for explaining a process following FIG. 10. (A) is sectional drawing for demonstrating the crack formed in the plating layer of a battery can, (b) is an enlarged view of the area | region XIIb of (a). The expanded sectional view which shows the method of forming a coating layer on the plating layer of a battery can. The figure which shows the structure of the coating layer formed on the plating layer of a battery can. The perspective view which shows Embodiment 2 of this invention and shows the battery can in which the safety valve was formed in the can bottom. The perspective view of the battery can of the state in which the coating layer was formed on the safety valve.

--Embodiment 1--
[Cylindrical secondary battery structure]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electricity storage device according to the present invention will be described with reference to the drawings, taking a lithium ion cylindrical secondary battery (hereinafter referred to as a cylindrical secondary battery) as an embodiment.
FIG. 1 is a cross-sectional view of the 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 has dimensions of, for example, an outer diameter of 40 mmφ and a height of 100 mm.

  The cylindrical secondary battery 1 has a battery container 4 having a structure sealed from the outside. The battery container 4 is manufactured by caulking a bottomed cylindrical battery can 2 and a hat-shaped battery lid 3 with a seal member 43 called a gasket interposed therebetween. The bottomed cylindrical battery can 2 is formed by pressing a metal plate such as iron or stainless steel, and a plating layer 2p (see FIG. 4) of nickel, tin or the like is formed on the entire outer and inner surfaces to prevent corrosion. Is formed.

  The battery can 2 has an opening 202 on the upper end side that is the open side. On the side of the opening 202 of the battery can 2, a groove 201 having a U-shaped cross section (groove-shaped deformed portion) constricted from the outer peripheral side to the inner peripheral side of the battery can 2 is formed. Inside the battery can 2, a power generation unit 20 including the electrode group 10 is accommodated, and a non-display nonaqueous electrolyte (not shown) is injected.

(Electrode group)
FIG. 3 is a perspective view showing the details of the structure of the electrode group 10, with a part thereof cut. As shown in FIG. 3, the electrode group 10 is configured by winding a positive electrode 11, a negative electrode 12, and first and second separators 13 and 14 around an axis 15.
The shaft core 15 has a hollow cylindrical shape, and the negative electrode 12, the first separator 13, the positive electrode 11, and the second separator 14 are wound around 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 outermost periphery is the negative electrode 12 and the first separator 13 wound around the outer periphery. The first separator 13 on the outermost periphery is fastened with an adhesive tape 19 (see FIG. 2).

  The positive electrode 11 is formed of an aluminum metal foil such as aluminum or aluminum alloy, and has a long shape. The positive electrode 11 is coated with a positive electrode mixture on both sides of the positive electrode metal foil 11a. It has a work part 11b. On one side edge in the longitudinal direction of the positive electrode metal foil 11a, a positive electrode mixture uncoated portion 11c is formed in which the positive electrode mixture is not applied and the positive electrode metal foil 11a is exposed. A number of positive electrode tabs 16 protruding upward in parallel with the shaft core 15 are integrally formed at equal intervals in the positive electrode mixture uncoated portion 11c.

The positive electrode mixture includes a positive electrode active material, a positive electrode conductive material, and a positive electrode binder. The positive electrode active material is preferably lithium oxide.
Examples of the positive electrode binder include polyvinylidene fluoride (PVDF) and fluororubber.

  The negative electrode 12 is formed of a copper-based metal foil such as copper or copper alloy, and has a long shape. The negative electrode mixture 12 is coated with a negative electrode mixture on both sides of the negative electrode metal foil 12a. A work part 12b is formed. On the lower side edge along the longitudinal direction of the negative electrode metal foil 12a, a negative electrode mixture uncoated portion 12c in which the negative electrode mixture is not applied and the copper foil is exposed is formed. A large number of negative electrode tabs 17 are integrally extended at equal intervals in the negative electrode mixture uncoated portion 12 c in the direction opposite to the positive electrode tab 16.

  The negative electrode mixture includes a negative electrode active material, a negative electrode binder, and a thickener. The negative electrode mixture may have a negative electrode conductive material such as acetylene black. As the negative electrode active material, it is preferable to use graphitic carbon, particularly artificial graphite.

The widths of the first separator 13 and the second separator 14 are formed larger than the width of the negative electrode mixture coating portion 12b formed on the negative electrode metal foil 12a. Moreover, the width | variety of the negative mix application part 12b formed in the negative electrode metal foil 12a is formed more largely than the width | variety of the positive mix application part 11b formed in the positive electrode metal foil 11a.
When the width of the negative electrode mixture coating portion 12b is larger than the width of the positive electrode mixture coating portion 11b, an internal short circuit due to precipitation of foreign matters is prevented.
The first and second separators 13 and 14 are, for example, polyethylene porous films having a thickness of 40 μm.

(Power generation unit)
The power generation unit 20 is formed by assembling the positive and negative current collecting plate members 27 and 21 to the electrode group 10.
The positive electrode current collecting member 27 is formed of, for example, an aluminum-based metal, and protrudes toward the shaft core 15 at the disk-shaped base portion 27a and the inner peripheral portion of the base portion 27a, and is pressed into the inner surface of the shaft core 15. Part 27b and an upper cylindrical part 27c protruding toward the battery lid 3 at the outer periphery. An opening 27d (see FIG. 2) for discharging a gas generated inside the battery is formed in the base 27a of the positive electrode current collecting member 27.

  The positive electrode tab 16 and the ring-shaped pressing member 28 of the positive electrode metal foil 11 a are welded to the outer periphery of the upper cylindrical portion 27 c of the positive electrode current collecting member 27. A number of the positive electrode tabs 16 are brought into close contact with the outer periphery of the upper cylindrical portion 27c of the positive electrode current collecting member 27, and a pressing member 28 is wound around the outer periphery of the positive electrode tab 16 and temporarily fixed. In this state, for example, ultrasonic welding is performed. Are joined together.

  A negative electrode current collecting member 21 is press-fitted and fixed to the outer periphery of the lower end portion of the shaft core 15. The negative electrode current collecting member 21 is made of, for example, copper, has an opening 21b that is press-fitted into the shaft core 15, and has an outer peripheral cylindrical portion 21c that protrudes toward the bottom side of the battery can 2 on the outer peripheral edge. Yes.

  The negative electrode tab 17 and the ring-shaped pressing member 22 of the negative electrode metal foil 12a are welded to the outer periphery of the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 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 collecting member 21, and the holding member 22 is wound around the outer periphery of the negative electrode tab 17 and temporarily fixed. In this state, for example, ultrasonic welding is performed. Are joined together.

A negative electrode conducting lead 23 made of a copper-based metal is welded to the lower surface of the negative electrode current collecting member 21.
The negative electrode conducting lead 23 is welded to the battery can 2 at the bottom of the battery can 2. As described above, since the inner surface of the battery can 2 is provided with the plating layer 2p (see FIG. 4) of nickel, tin, etc., the negative electrode conducting lead 23 can be welded to the battery can 2 by resistance welding or the like. it can.

  In order to weld the negative electrode energizing lead 23 to the battery can 2, an electrode rod (not shown) is inserted through an opening 27 e formed in the positive electrode current collecting member 27, and the negative electrode energizing lead 23 is connected to the battery at the tip of the electrode rod. Resistance welding is performed by pressing against the inner surface of the bottom of the can 2.

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

  In addition, a flexible connection member 33 formed by laminating a plurality of aluminum foils is joined to the upper surface of the base portion 27a of the positive electrode current collecting member 27 by welding one end thereof.

(Battery cover unit)
A battery lid unit 30 is disposed above the power generation unit 20.
A ring-shaped insulating plate 34 made of an insulating resin material having a circular opening 34 a is placed on the upper cylindrical portion 27 c of the positive electrode current collecting member 27.
The insulating plate 34 has an opening 34a (see FIG. 2) and a side portion 34b protruding downward. A connecting plate 35 is fitted in the opening 34 a of the insulating plate 34. The other end of the flexible connection member 33 is welded and fixed to the lower surface of the connection plate 35.

  The connection plate 35 is formed of an aluminum alloy, 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. The thickness of the connection plate 35 is, for example, about 1 mm. At the center of the connection plate 35, a thin dome-shaped projection 35a is formed, and a plurality of openings 35b (see FIG. 2) 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 diffusion bonding. The diaphragm 37 is formed of an aluminum alloy, and has a cleavage portion 37 a that is a circular cut centered on the center portion of the diaphragm 37. The cleaving portion 37a is formed by crushing the upper surface side into a U shape by pressing and thinning the remaining portion.

  The diaphragm 37 is provided for ensuring the safety of the battery. When the internal pressure of the battery increases, the diaphragm 37 has a function of cleaving at the cleaving portion 37a and releasing the internal gas.

The diaphragm 37 fixes the peripheral portion 3a of the battery lid 3 at the peripheral portion. As shown in FIG. 2, the diaphragm 37 initially has a side portion 37 b erected vertically toward the battery lid 3 side at the peripheral portion. The battery lid 3 is accommodated in the side portion 37b, and the side portion 37b is bent and fixed to the upper surface side of the battery lid 3 by caulking.
The battery lid 3 is formed of iron such as carbon steel, and a plating layer 2p of nickel, tin or the like is applied to the entire outer and inner surfaces as shown in FIG. The battery lid 3 has a hat shape having a disc-shaped peripheral edge portion 3a that contacts the diaphragm 37 and a headless bottomless cylindrical portion 3b that protrudes upward from the peripheral edge portion 3a.

The battery lid 3, the diaphragm 37, the insulating plate 34 and the connection plate 35 are integrated to form a battery lid unit 30. A method for assembling the battery lid unit 30 will be described below.
First, the battery lid 3 is fixed to the diaphragm 37. The diaphragm 37 and the battery lid 3 are fixed by caulking or the like. As shown in FIG. 2, since the side portion 37 b of the diaphragm 37 is initially formed perpendicular to the base portion 37 d, the peripheral edge portion 3 a of the battery lid 3 is disposed in the side portion 37 b of the diaphragm 37. Then, the side portion 37b of the diaphragm 37 is deformed by a press or the like, and the upper surface and the lower surface of the peripheral portion of the battery lid 3 and the outer peripheral side surface are covered with pressure.

  On the other hand, the connection plate 35 is fitted into the opening 34 a of the insulating plate 34 and attached. Next, with the insulating plate 34 sandwiched therebetween, the protruding portion 35a of the connection plate 35 is welded to the bottom surface of the diaphragm 37 to which the battery lid 3 is fixed. As the welding method in this case, resistance welding or friction diffusion bonding can be used. As a result, the connecting plate 35 is welded to the diaphragm 37 fixed by the battery lid 3 with the insulating plate 34 interposed therebetween, so that an integrated battery lid unit 30 is configured.

(Sealing structure)
Covering the peripheral edge of the side portion 37b of the diaphragm 37, a seal member 43, usually called a gasket, is provided. The seal member 43 is made of, for example, PFA (polytetrafluorene), PPF (polyfemil sulfide), or the like.

  As shown in FIG. 2, the seal member 43 initially includes an outer peripheral wall portion 43 b that is formed on the peripheral side edge of the ring-shaped base portion 43 a so as to stand substantially vertically toward the upper direction, and an inner peripheral side. Further, it has a shape having a cylindrical portion 43c formed to hang substantially vertically downward from the base portion 43a.

  As will be described in detail later, the outer peripheral wall 43b of the seal member 43 is bent together with the battery can 2 by a press or the like, and the diaphragm 37 and the battery lid 3 are pressed in the axial direction by the base 43a and the outer peripheral wall 43b. It is caulked to do. Accordingly, 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 seal member 43.

A predetermined amount of non-aqueous electrolyte is injected into the battery can 2. As an example of the non-aqueous electrolyte, it is preferable to use a solution in which a lithium salt is dissolved in a carbonate solvent. Examples of the lithium salt include lithium fluorophosphate (LiPF ₆ ), lithium fluoroborate (LiBF ₄ ), and the like. Examples of carbonate solvents include ethylene carbonate (EC), dimethyl carbonate (DMC), propylene carbonate (PC), methyl ethyl carbonate (MEC), or a mixture of solvents selected from one or more of the above solvents, Is mentioned.

[Coating layer of battery can plating layer]
4 is an enlarged cross-sectional view of a region A of the battery can illustrated in FIG.
As described above, the plating layer 2p of nickel, tin, or the like is formed on the inner and outer surfaces of the battery can 2. On the opening 202 side of the battery can 2, a groove 201 having a U-shaped cross section constricted from the outer peripheral side to the inner peripheral side of the battery can 2 is formed. In addition, the battery can 2 is formed with a bent portion 203 that is bent at a substantially right angle toward the inner peripheral side at the upper portion of the groove 201.
Although details will be described later, the groove 201 is formed by grooving, and the bent portion 203 is formed by plastic deformation of the battery can 2 by press working.

When the groove 201 or the bent portion 203 is formed in the battery can 2, cracks are likely to occur in the plating layer 2 p formed on the groove 201 or the bent portion 203 which is a plastically deformed portion. If a crack is generated in the plating layer 2p, the battery can 2 is corroded due to aging. For this reason, the coating layer M is formed on the plating layer 2p in the plastic deformation part of the battery can 2. The covering layer M is made of a resin having a larger ionization tendency than that of the material constituting the battery can 2, for example, containing metal particles such as zinc, aluminum, and magnesium.
The coating layer M can suppress the corrosion of the battery can 2 even when the plating layer 2p in the plastic deformation portion of the battery can 2 is cracked. Reliability can be improved.
Next, an embodiment of a method for manufacturing a power storage element of the present invention will be described.

[Method of manufacturing cylindrical secondary battery]
FIG. 5 is a flowchart showing a method of manufacturing the cylindrical secondary battery shown in FIG. 1, and FIGS. 6 to 13 are diagrams for explaining each process.
Hereinafter, with reference to these drawings, a method for manufacturing a cylindrical secondary battery of the present invention will be described.

(Production of electrode group)
First, the electrode group 10 is produced.
As a preparation process for producing the electrode group 10, the positive electrode 11 is produced in step S1-1, and the negative electrode 12 is produced in step S1-2.
In step S1-1, as described above, the positive electrode mixture coated portion 11b and the positive electrode mixture uncoated portion 11c are formed on both surfaces of the positive electrode metal foil 11a, and a large number of positive electrode tabs 16 are formed on the positive electrode metal foil 11a. The positive electrode 11 formed integrally with is manufactured.
Similarly, in step S1-2, the negative electrode mixture coated portion 12b and the negative electrode mixture uncoated portion 12c are formed on both surfaces of the negative electrode metal foil 12a, and a number of negative electrode tabs 17 are integrally formed on the negative electrode metal foil 12a. The negative electrode 12 was prepared.

In step S2, the positive electrode 11 and the negative electrode 12 are wound around the shaft core 15 as follows.
The innermost side edges of the first separator 13 and the second separator 14 are welded to the shaft core 15. Next, the first separator 13 and the second separator 14 are wound around the shaft 15 one to several times, the negative electrode 12 is sandwiched between the second separator 14 and the first separator 13, The positive electrode 11 is sandwiched between the first separator 13 and the second separator 14. In this state, the electrode group 10 is manufactured by winding a predetermined number of turns.

(Power generation unit production)
Next, the power generation unit 20 is produced.
In step S3, the positive electrode tab 16 is joined to the positive electrode current collector 27 as follows.
One end portion of the connection member 33 is welded to the base portion 27a of the positive electrode current collecting member 27 by, for example, ultrasonic welding. Next, the lower cylindrical portion 27 b of the positive electrode current collecting member 27 to which the connecting member 33 is welded is fitted to the upper end of the shaft core 15. The positive electrode tabs 16 are distributed almost uniformly around the entire circumference of the upper cylindrical portion 27 c of the positive electrode current collecting member 27, and the pressing member 28 is wound around the outer periphery of the positive electrode tab 16. Then, the positive electrode tab 16 and the pressing member 28 are welded to the positive electrode current collecting member 27 by ultrasonic welding or the like.

In step S4, the negative electrode tab 17 is joined to the negative electrode current collector 21 as follows.
The negative electrode current collecting member 21 is inserted into the lower portion of the shaft core 15 of the electrode group 10. Next, the negative electrode tabs 17 are distributed almost uniformly around the entire outer periphery of the outer peripheral cylindrical portion 21 c of the negative electrode current collecting member 21, and the pressing member 22 is wound around the outer periphery of the negative electrode tab 17. The negative electrode tab 17 and the holding member 22 are welded to the negative electrode current collecting member 21 by ultrasonic welding or the like. The negative electrode conducting lead 23 is welded to the negative electrode current collecting member 21 so as to straddle the lower end surface of the shaft core 15 and the negative electrode current collecting member 21.
In this way, the power generation unit 20 illustrated in FIG. 2 is produced.

(Battery can production)
In parallel with steps S1 to S4, the battery can 2 is manufactured as follows in step S5.
In order to manufacture the battery can 2, a metal plate having a uniform outer shape and a circular thickness is prepared. Examples of the metal plate include iron and stainless steel having a thickness of about 0.4 to 0.8 mm.
As shown in FIG. 6, the metal plate is drawn to form a cylindrical portion 200a having a flange 200b with a predetermined width around it.
By repeatedly performing the drawing process, as shown in FIG. 7, a cylindrical portion 200 a having a depth necessary for the battery can 2 is produced.
And the flange 200b is cut | disconnected and the bottomed cylindrical battery can 2 perpendicular | vertical from the can bottom 2c to the front-end | tip part 204 (refer FIG. 8) by the side of an opening is formed.
In step S6, a plated layer 2p (see FIG. 8) of nickel, tin, or the like is formed on the inner and outer surfaces of the battery can 2.

(Assembly process)
In step S7, the power generation unit 20 is accommodated in the battery can 2 and connected to the inner surface of the can bottom 2c as follows.
The negative electrode conducting lead 23 of the power generation unit 20 accommodated in the battery can 2 is welded to the battery can 2 by resistance welding or the like. As described above, an electrode rod (not shown) is inserted from the opening 27 e of the positive electrode current collector 27, inserted through the hollow portion of the shaft core 15, and the negative electrode energizing lead 23 is pressed against the bottom of the battery can 2 and welded.
FIG. 8 illustrates a state in which the power generation unit 20 is housed in the battery can 2.

In step S8, the battery can 2 is grooved as follows to form a groove 201 having a U-shaped cross section.
As shown in FIG. 9, the guide support 220 is mounted in the opening 202 of the battery can 2, and the grooving device 230 is disposed on the outer periphery of the battery can 2 at a predetermined distance from the front end portion 204 of the battery can 2. Deploy. The grooving device 230 is provided with a ring-shaped grooved roller 232 on the outer periphery of the shaft portion 231.
From the outer peripheral surface of the battery can 2, the grooving roller 232 is pushed inward of the battery can 2, and in this pushed state, the battery can 2 is rotated around its axis. Accordingly, a groove 201 having a U-shaped cross section is formed from the outer peripheral surface of the battery can 2 toward the inner peripheral surface above the power generation unit 20 in the battery can 2 and in the vicinity of the upper end portion of the positive electrode current collecting member 27. .

In step S9, as shown in FIG. 10, the battery lid unit 30 assembled in an assembly process different from the assembly process of the battery can 2 is accommodated in the battery can 2, and the accommodated battery lid unit 30; The electrode group 10 of the power generation unit 20 is electrically connected by the connection member 33.
As described above, the battery lid unit 30 includes the insulating plate 34, the connection plate 35 fitted into the opening 34 a of the insulating plate 34, the diaphragm 37 welded to the connection plate 35, and the battery lid 3 fixed to the diaphragm 37 by caulking. It is comprised by. The method for producing the battery lid unit 30 is as described above.

Prior to disposing the battery lid unit 30 on the power generation unit 20, the seal member 43 is placed on the groove 201 of the battery can 2. As shown in FIG. 2, the seal member 43 in this state has a structure having an outer peripheral wall 43b perpendicular to the base 43a above the ring-shaped base 43a.
Then, one end portion of the connecting member 33 is joined to the upper surface of the base portion 27a of the positive electrode current collecting member 27 accommodated in the battery can 2 by ultrasonic welding or the like.
Next, the other end of the connection member 33 is joined to the battery lid unit 30.
The other end portion side of the connection member 33 is folded back, and the connection plate 35 of the battery lid unit 30 is held in a state of being brought into contact with the other end portion folded back of the connection member 33 by a holder (not shown). And laser welding.

(Electrolyte injection)
In step S10, a predetermined amount of non-aqueous electrolyte is injected into the battery can 2 in which the power generation unit 20 is accommodated. As described above, for example, a solution in which a lithium salt is dissolved in a carbonate-based solvent is used as the nonaqueous electrolytic solution.

(Sealing)
In step S11, the battery lid unit 30 and the battery can 2 are sealed by caulking as follows.
As shown in FIG. 11, the front end portion 204 of the battery can 2 is bent at a substantially right angle with respect to the axis toward the inner peripheral side of the battery can 2.
A sizing mold 240 is brought into contact with the outer peripheral surface of the battery can 2 around the groove 201 to support the battery can 2. In this state, a sizing die 270 is disposed on the front end portion 204 side of the battery can 2 and the front end portion 204 side of the battery can 2 is pressed.

  As the sizing mold 270 is lowered, the front end portion 204 side of the battery can 2 is bent to form a bent portion 203. The seal member 43 is also bent together with the battery can 2. The seal member 43 is compressed by being sandwiched between the bent portion 37 c of the diaphragm 37 that is crimped to the peripheral edge portion 3 a of the battery lid 3 and the region between the U-shaped groove 201 and the tip end portion 204 in the battery can 2. Is done. Thereby, the battery lid unit 30 and the front end side of the battery can 2 are caulked with the seal member 43 interposed therebetween, and are sealed from the outside.

  In the above press work, if it is difficult to bend the tip portion 204 in a state where the cylindrical portion of the battery can 2 is vertical, first, a press die having a slope is used, and the slope of the press die is used. You may press-process so that the front-end | tip part 204 of the battery can 2 may incline at a predetermined angle. Thereafter, the sizing mold 270 illustrated in FIG. 11 may be used to perform a pressing process in which the tip end 204 side of the battery can 2 is bent substantially perpendicularly to the axis.

[Cover of battery can plating layer]
In the grooving process in step S8 and the caulking and sealing process in step S11, the battery can 2 is plastically deformed in the regions of the groove 201 and the bent portion 203. In the region of the groove 201 and the bent portion 203 which are plastic deformation portions in this grooving step, cracks k as shown in FIGS. 12A and 12B are likely to enter the plating layer 2p formed on the surface. . FIG. 12B is an enlarged view of a region XIIb in FIG.
If the crack k occurs, the battery can 2 may be corroded by moisture due to aging.

Cracks k may occur in the plating process 2b in the plating layer 2p formed in the groove 201 or the bent portion 203, which is a plastic deformation region in the battery can 2. The crack k is formed so shallow that it almost terminates in the plating layer 2 p and does not reach the surface of the battery can 2.
In the state where the crack k is exposed, the inorganic salt or organic matter ionized into the air or moisture may permeate the plating layer 2p thinned by the crack k, and thereby the surface of the battery can 2 may be corroded.

  Therefore, in step S12, as shown in FIG. 13, a coating layer M containing a metal material having a higher ionization tendency than the battery can 2 is formed on the plating layer 2p in the plastic deformation portion. For example, as shown in FIG. 13, a resin containing metal particles is applied by a spray 290. The coating layer M applied on the plating layer 2p in the plastic deformation portion can make the content of metal particles after drying 95% or more. As the coating layer M, for example, a resin such as a butyl rubber-based adhesive that contains metal particles made of zinc, aluminum, magnesium, or the like, which has a higher ionization tendency than iron or stainless steel that is a material of the battery can 2 is used. Can be used.

FIG. 14 is an enlarged view showing the configuration of the coating layer M formed on the plating layer 2p of the battery can.
In one embodiment of the present invention, the coating layer M is provided on the plating layer 2p. Coating layer M is present in the resin M _b, the metal particles M _a large ionization tendency is contained numerous than the material of the battery can 2. Since the metal particles Ma have _a higher ionization tendency than the battery can 2, oxidation of the battery can 2 can be prevented.

--Embodiment 2-
15 is a perspective view showing a battery can in which a safety valve is formed on the bottom of the can according to Embodiment 2 of the present invention, and FIG. 16 is a perspective view of the battery can in a state where a coating layer is formed on the safety valve. It is.
As shown in FIG. 15, a safety valve 100 is formed on the can bottom 2 c of the battery can 2. The safety valve 100 can be formed, for example, by pressing after the battery can 2 illustrated in FIG. 7 is formed in the first embodiment.
The safety valve 100 has a cleavage portion 100a. The cleaving part 100a is formed by pressing the outer surface side of the can bottom 2c of the battery can 2 into a U-shape by pressing, and is formed by the crushed remaining part. In the example illustrated in FIG. 15, the cleavage portion 100 a has a circular arc shape portion and a plurality of short straight portions extending outward from the circular arc shape portion. However, the shape of the cleavage part 100a can be set arbitrarily.

When the internal pressure of the cylindrical secondary battery 1 rises, the safety valve 100 has a function of cleaving at the cleaving portion 100a and releasing the internal gas.
Since the cleavage part 100a is plastically deformed and thinned, cracks k are likely to enter the plating layer 2p originally formed on the safety valve 100.
Therefore, as shown in FIG. 16, a coating layer M is formed on the plating layer 2p formed in the safety valve 100 region. The configuration of the coating layer M is the same as that in the first embodiment.

As described above, in the embodiment of the present invention, the metal particles Ma having _a higher ionization tendency than the material of the battery can 2 are contained on the plating layer 2p formed on the outer surface of the plastic deformation portion in the battery can 2. A coating layer M made of a resin was provided. For this reason, there exists an effect which suppresses corrosion of the battery can 2 and improves the reliability of a cylindrical secondary battery.

In the above embodiment, exemplified coating layer M formed on the plating layer 2p of the battery can 2, zinc, aluminum, as a material constituted by a resin M _b metal particles M _a is contained in such magnesium. However, the metal particles M _a contained in the resin M _b are not limited to zinc, aluminum, and magnesium, and may be those having a higher ionization tendency than the material of the battery can 2, and are not limited to one type. The metal particles Ma of _a plurality of types of materials may be contained.

In the above embodiment, the coating layer M of metal particles M _a is made of a resin M _b that are contained is exemplified as applied structure. However, the metal foil may be transferred onto the plating layer 2p by hot pressing. The metal foil should just have a larger ionization tendency than the material of the battery can 2.

  In the above embodiment, the plating layer 2p is illustrated as being formed of nickel or tin having a smaller ionization tendency than the material constituting the battery can 2. However, the plating layer 2p may be formed of a material having a greater ionization tendency than the material constituting the battery can 2.

  The second embodiment may be applied to the first embodiment, and the coating layer M may be provided on the concave portion 201 having a U-shaped cross section in the battery can 2, the bent portion 203, and the can bottom 2 c of the battery can 2.

  In the above embodiment, the lithium ion cylindrical secondary battery has been described as an example. However, the present invention is not limited to the lithium battery, and may be applied to other cylindrical secondary batteries such as a nickel hydride battery and a nickel cadmium battery. You can make an application.

The present invention can also be applied to a prismatic secondary battery.
A prismatic secondary battery has a structure in which a safety valve is formed on a battery lid that seals a battery can. For such secondary batteries, a coating layer can be provided on a safety valve formed on the battery lid.
Furthermore, the present invention can also be applied to lithium ion capacitors, electric double layer electrolytic capacitors, and the like.
In short, the coating layer of the present invention can be provided on plastically deformed portions of various metal members that constitute a battery or a capacitor.

  In addition, the power storage device of the present invention can be variously modified and configured within the scope of the gist of the invention. In short, the present invention can be applied to the outer surface of the plastically deformed portion of a metal member such as a container. Any coating layer containing a corrosion-inhibiting metal material having a greater ionization tendency than that of a metal member may be provided on the formed plating layer.

1 Cylindrical secondary battery 2 Battery can (container)
2c Can bottom 2p Plating layer 3 Battery lid 4 Battery container 10 Electrode group 20 Power generation unit 30 Battery lid unit 100 Safety valve 100a Cleavage part (plastic deformation part)
200 Metal plate 201 Groove (plastic deformation part)
203 Bent part (plastic deformation part)
M coating layer M _a metal particle M _b resin

Claims (9)

A power storage element including a metal member having a plating layer formed on the outer surface, a power generation unit accommodated therein, and a container filled with an electrolyte solution,
The container has a plastic deformation portion formed by processing, and a corrosion-inhibiting metal material having a higher ionization tendency than the metal member is included on the plating layer formed on the outer surface of the plastic deformation portion. A power storage element provided with a coating layer. The electricity storage device according to claim 1,
The power storage element, wherein the coating layer is a resin layer containing metal particles. The electricity storage device according to claim 2,
The said coating layer is an electrical storage element whose said metal particle content rate is 95% or more. The electricity storage device according to claim 1,
The electrical storage element, wherein the metal member is iron or stainless steel. The electricity storage device according to claim 4,
The electrical storage element, wherein the corrosion-inhibiting metal material includes any of zinc, aluminum, and magnesium. The electricity storage device according to claim 5,
The power storage element, wherein the plating layer is nickel or tin. In the electrical storage element of any one of Claims 1 thru | or 6,
The container is a battery can having a cylindrical shape, and the plastic deformation portion is a groove-shaped deformation portion in which the battery can is constricted from an outer peripheral side toward an inner peripheral side. In the electrical storage element of any one of Claims 1 thru | or 6,
The container is a battery can having a cylindrical shape, and the plastic deformation portion is configured to fix a peripheral portion of a battery lid disposed inside the battery can at an axial end portion of the battery can. A power storage element, which is a bent portion that bends the tip of the container to the inner peripheral side. In the electrical storage element of any one of Claims 1 thru | or 6,
The plastic deformation portion is a power storage element, which is a cleavage portion of a safety valve formed by thinning the container.

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