阅读说明：本技术 封口体 (Sealing body ) 是由 莲沼贵司 山冈俊和 于 2014-02-18 设计创作，主要内容包括：提供容易制造并且能够进一步小型化的密闭型电池用的封口体。密闭型电池用的封口体(1)具有：第一正极盖,其具有敛缝部以及排气口；(2)导电性金属箔,其位于第一正极盖上；(3)保护元件,其位于导电性金属箔上,且具有熔断器功能；以及(4)第二正极盖,其位于保护元件上,且具有排气口,通过上述第一正极盖的敛缝部对上述导电性金属箔、上述保护元件以及上述第二正极盖进行敛缝。(Provided is a sealing body for a sealed battery, which is easy to manufacture and can be further miniaturized. A sealing body (1) for a sealed battery comprises: a first positive electrode cap having a caulking portion and an exhaust port; (2) a conductive metal foil on the first positive electrode cap; (3) a protection element which is located on the conductive metal foil and has a fuse function; and (4) a second positive electrode cap that is positioned on the protection element and has an exhaust port, and the conductive metal foil, the protection element, and the second positive electrode cap are caulked by a caulking portion of the first positive electrode cap.)

1. A sealing body for a sealed battery, the sealing body comprising:

a first positive electrode cap having a caulking portion and an exhaust port;

a conductive metal foil directly on a surface of the first positive electrode cap;

a protection element which is located on the conductive metal foil and has a fuse function; and

a second positive electrode cap which is provided on the protective member and has an exhaust port, an

An insulating gasket provided around the conductive metal foil, the protective element, and the second positive electrode cap and on the flange portion of the second positive electrode cap, and not provided between the conductive metal foil and the first positive electrode cap,

wherein the conductive metal foil, the protection element, and the second positive electrode cap are fixed by the caulking portion of the first positive electrode cap and the insulating gasket, and a contact portion between the first positive electrode cap and the conductive metal foil is sufficiently large so that the electrical connection between the first positive electrode cap and the conductive metal foil does not require welding.

2. The closure body of claim 1,

the protection element having a fuse function has:

(i) a layered member formed of an insulating resin and having at least one through opening;

(ii) a conductive metal thin-layer electrode located on each main surface of the layered member; and

(iii) and a fuse layer located on a side surface defining at least one of the through openings and electrically connected to the conductive metal thin-layer electrode.

3. The closure body of claim 2,

the conductive metal thin-layer electrode on the conductive metal foil side among the conductive metal thin-layer electrodes is omitted, and the other conductive metal thin-layer electrode and the conductive metal foil are directly connected through the fuse layer.

4. The sealing body of claim 2 or 3,

the fuse layer includes a plurality of metal layers having different melting points.

5. The sealing body as claimed in one of claims 2 to 3,

the fuse layer includes a metal layer formed of Ni, and a metal layer formed of Sn, a Sn-Cu alloy, or a Sn-Bi alloy.

6. The sealing body as claimed in one of claims 1 to 3,

the conductive metal foil is an aluminum foil.

7. The sealing body as claimed in one of claims 1 to 3,

the sealing body is a sealing body for a cylindrical battery.

8. The sealing body as claimed in one of claims 1 to 3,

the sealing body is used for a lithium ion rechargeable battery.

9. The closure body of claim 1,

the conductive metal foil is an explosion-proof valve.

10. The closure body of claim 9,

the explosion-proof valve is configured to release gas pressure within the cell at a pressure of 10-15 kgf.

11. The closure body of claim 1,

the conductive metal foil is configured to prevent the electrolyte from leaking to the outside of the battery via the vent.

12. The closure body of claim 1,

the protection element is a current interrupting mechanism.

13. The closure body of claim 4,

an excessive current is configured to flow through the fuse layer to generate heat to melt a first metal layer having a lower melting point than a second metal layer, wherein the excessive current is configured to flow through the second metal layer, wherein the excessive current is configured to be cut off in response to flowing through the second metal layer.

14. A sealed battery having the sealing body according to any one of claims 1 to 13.

15. The sealed battery according to claim 14, wherein,

the sealed battery is a cylindrical battery.

16. The sealed battery according to claim 14 or 15, wherein,

the sealed battery is a lithium-ion rechargeable battery.

Technical Field

The present invention relates to a sealing body for a sealed battery.

Background

Lithium ion batteries have the advantages of high energy density, high operating voltage, excellent voltage stability during discharge, little self-discharge, no memory effect, and the like, and are therefore suitable for use as power sources for, for example, mobile phones, personal computers, video cameras, and the like. However, in a rechargeable battery such as a lithium ion battery containing an organic solvent as an electrolyte, there is a problem that the electrolyte is decomposed due to abnormality such as overcharge or internal short circuit, or misuse, and gas is generated in the battery, and the internal pressure of the battery rises.

In order to solve such a problem, for example, patent document 1 discloses a sealed battery having a sealing body 100, and as shown in fig. 1, the sealing body 100 includes: a valve cap 102 having a vent hole, an explosion-proof valve 106 positioned over the valve cap 102 via an internal gasket 104, a PTC element 108 positioned over the explosion-proof valve 106, and a positive terminal 110 having a vent hole positioned over the PTC element 108. When the internal pressure of the sealed battery having the sealing member exceeds a set value, the explosion-proof valve 106 is operated to discharge gas to the outside of the battery, thereby preventing the internal pressure of the battery from increasing.

Prior art documents

Patent document

Patent document 1: japanese laid-open patent publication No. 11-283588

However, in the sealing body as described above, since the explosion-proof valve serves as a current path in a normal state, it is necessary to weld the explosion-proof valve 106 and the bonnet 102 at the connection position 112 thereof in order to reliably electrically connect them. Therefore, a welding step is required for manufacturing the sealing body, which causes a problem that the manufacturing process becomes complicated.

The PTC element operates (trips) at an abnormal time to have a high resistance, and can cut off a current flowing through the PTC element, but a minute current (leakage current) flows after the operation. However, depending on the kind of abnormality, the circuit is required to be completely disconnected. Therefore, in the conventional sealing body, a function as a Current Interrupt Device (CID) is added to the explosion-proof valve in order to Interrupt the minute Current. Therefore, in the sealing body 100 described above, an insulating inner gasket 104 is provided between the bonnet 102 and the flange portion of the explosion-proof valve 106 so that the bonnet 102 and the explosion-proof valve 106 can be electrically disconnected after the explosion-proof valve is operated. Therefore, there is a problem that the thickness of the entire sealing body is increased by the thickness of the gasket. Further, since the number of components is increased, the influence of variations in the dimensions (thicknesses) inherent to the respective components is increased, and there is also a problem that the load pressure applied to the PTC element by caulking is unstable, and the withstand voltage characteristics of the PTC element are degraded.

Further, since the explosion-proof valve has both a function as an explosion-proof valve and a function as a current interrupting mechanism, there is a problem that the shape and structure of the explosion-proof valve are complicated, and the processing of the explosion-proof valve itself is complicated.

Disclosure of Invention

Problems to be solved by the invention

Therefore, an object of the present invention is to provide a sealing body for a sealed battery that is easy to manufacture and can be further miniaturized.

Means for solving the problems

In a first aspect, the present invention provides a sealing body for a sealed battery, the sealing body including:

(1) a first positive electrode cap having a caulking portion and an exhaust port;

(2) a conductive metal foil on the first positive electrode cap;

(3) a protection element which is located on the conductive metal foil and has a fuse function; and

(4) a second positive electrode cap which is provided on the protective member and has an exhaust port,

the conductive metal foil, the protection element, and the second positive electrode cap are fixed by a caulking portion of the first positive electrode cap.

In the sealing body of the present invention, since the protective element having the fuse function of the above (3) functions as a current interrupting mechanism, the conductive metal foil only needs to function as an explosion-proof valve. Therefore, the conductive metal foil does not need to take a complicated shape and structure. In addition, it is not necessary to ensure insulation between the flange portion of the conductive metal foil and the first positive electrode cap. Therefore, it is not necessary to dispose an insulating gasket between the conductive metal foil and the first positive electrode cap. Further, the conductive metal foil is in surface contact with the first positive electrode cap, and the conductive metal foil is reliably electrically connected to the first positive electrode cap by pressing the caulking portion of the first positive electrode cap, so that it is not necessary to weld the conductive metal foil and the first positive electrode cap.

A second object of the present invention is to provide a sealed battery including the sealing member of the present invention.

Effects of the invention

The sealing body of the present invention uses a protective element having a fuse function as a current interrupting mechanism, and can simplify the shape and structure of a conductive metal foil as an explosion-proof valve, and it is not necessary to weld the conductive metal foil and a first positive electrode cap. This simplifies the production of the sealing body. Further, a more compact sealing body can be provided.

Drawings

Fig. 1 schematically shows a sealing body for a conventional sealed battery in a cross-sectional view.

Fig. 2 schematically shows an embodiment of the sealing body for a sealed battery according to the present invention in a cross-sectional view.

Fig. 3 schematically shows the closure of fig. 2 in a top view.

Detailed Description

Hereinafter, the sealing member of the present invention will be described in detail with reference to the accompanying drawings. However, the sealing member of the present invention is not limited to the illustrated embodiment.

Fig. 2 schematically shows an embodiment of the sealing member of the present invention in a cross-sectional view taken along the thickness direction thereof, and fig. 3 schematically shows an embodiment of the sealing member of the present invention in a plan view.

The illustrated sealing member 10 is a sealing member for a cylindrical battery, and includes a conductive metal foil 14, a protective element 16 having a fuse function, and a second positive electrode cap 18 laminated in this order on a first positive electrode cap 12, and the sealing member 10 includes an insulating gasket 22 positioned around the above members and on a flange portion (outer edge portion) 20 of the second positive electrode cap 18, and these members are fixed by a caulking portion 24 positioned at an edge portion of the first positive electrode cap 12.

In the illustrated embodiment, first positive electrode cap 12 has an exhaust port 26 in the center thereof. The gas discharge port 26 is provided to discharge gas to the outside of the battery when the internal pressure of the battery rises due to gas generated inside the battery by an abnormal reaction of the electrolyte and/or the active material, etc., and the explosion-proof valve is operated. Therefore, it is preferable that a protective element having a fuse function is not present directly above the exhaust port 26. First positive electrode cap 12 has a caulking portion 24, and after other members constituting the sealing body are provided at predetermined positions on first positive electrode cap 12, the caulking portion 24 is bent inward to fix the other members.

In the present invention, the first positive electrode cover is formed of a conductive metal. The conductive metal is not particularly limited, and for example, when the sealing member is a sealing member for a lithium ion battery, aluminum or an aluminum alloy is preferable.

In the illustrated embodiment, the conductive metal foil 14 is a disk-shaped metal foil, and functions as an explosion-proof valve. In addition, the conductive metal foil 14 prevents the electrolyte from leaking to the outside of the battery through the vent port in a normal state.

In the present invention, the metal material forming the conductive metal foil 14 is not particularly limited as long as it is a material having corrosion resistance to the electrolytic solution, and for example, when the sealing body is a sealing body for a lithium ion battery, aluminum or an aluminum alloy is preferable.

The thickness of the conductive metal foil is not particularly limited as long as it can function as an explosion-proof valve. The thickness of the conductive metal foil is appropriately determined by those skilled in the art depending on the structure of the sealing body, particularly the inner diameter of the protection element, so that the explosion-proof valve operates (breaks) when a desired pressure (generally 10 to 15kgf) is applied.

The conductive metal foil can be easily produced by a general metal foil production method such as rolling.

In the present invention, the protection element having a fuse function is a protection element having a non-recovery fuse function that can be fused when an excessive current flows through the sealing body, and can cut off the excessive current.

In the illustrated embodiment, the protection element 16 is an annular protection element (disk-shaped protection element) including:

(i) a layered member formed of an insulating resin and having at least one through opening;

(ii) a conductive metal thin-layer electrode located on each main surface of the layered member; and

(iii) and a fuse layer located on a side surface defining at least one of the through openings and electrically connected to the conductive metal thin-layer electrode.

In the illustrated embodiment, the fuse layer and the conductive metal thin-layer electrode on each main surface of the layered member are omitted for simplicity, and the protective element 16 as a whole is illustrated. This disc-type protective element is disclosed, for example, by international publication No. 2012/118153 (the entire disclosure including the protective element illustrated in the drawings and the manufacturing method thereof is incorporated in the present specification by reference).

The layered member formed of the insulating resin has at least one through opening. The through opening portion extends in the thickness direction of the layered member and penetrates the layered member, and when gas is generated inside the battery and the explosion-proof valve is operated, the through opening portion is in gas communication with the gas outlet 26 of the first positive electrode cap and the gas outlet 28 of the second positive electrode cap so that the gas generated inside the battery can be discharged to the outside of the battery. The positions and the number of the through openings are not particularly limited, and one through opening may be provided at the center of the layer member, or a plurality of, for example, two, three, or four through openings may be provided at the peripheral portion of the annular layer member having the center through opening.

The insulating resin constituting the layered member is not particularly limited as long as it is a resin having insulating properties. For example, resins such as polyethylene, polypropylene, polycarbonate, fluororesin, ABS resin, polycarbonate-ABS alloy resin, PBT resin, and elastomer can be exemplified. In particular, resins such as polyethylene and polyvinylidene fluoride are preferably used.

The layered member has conductive metal thin-layer electrodes disposed on both main surfaces thereof. The conductive metal thin-layer electrode is not particularly limited as long as it is a thin layer of a conductive metal (for example, having a thickness of about 0.1 μm to 100 μ n), and may be made of a metal such as copper, nickel, aluminum, or gold, or may be formed of a plurality of thin metal layers.

A layered member having a conductive metal thin-layer electrode on each main surface can be manufactured by simultaneously pressing an insulating resin constituting the layered member and a metal sheet (or metal foil) constituting a metal thin layer, thereby obtaining an extrudate in a state where the insulating resin is sandwiched between the metal sheets (or metal foils). In another embodiment, the pressure-bonded product may be produced by, for example, obtaining a laminate of insulating resin by pressing, sandwiching the laminate between metal sheets (or metal foils), and thermally pressing the metal sheets (or metal foils) together to obtain a pressure-bonded product. In another embodiment, the conductive metal thin-layer electrode may be formed on both main surfaces by plating a conductive metal on the insulating resin layer member. The layered member having a conductive metal (such as an extrudate or a pressure-bonded product) obtained in this way is in a state in which a plurality of layered members of insulating resin having conductive metal thin-layer electrodes on both main surfaces are adjacent to each other and are assembled, and by cutting the layered members in a predetermined shape and size, a single layered member having a conductive thin layer can be obtained.

The form of the layered member is not particularly limited as long as the dimension in the thickness direction is smaller than the dimensions in the other directions, and is preferably very small (for example, a sheet form). In the illustrated embodiment, the planar shape of the layer member is circular, but is not particularly limited, and is preferably a shape corresponding to the planar shape of the sealing member.

The protective element has a fuse layer located on a side surface defining at least one through opening and electrically connected to conductive metal thin-layer electrodes located on both main surfaces of the layered member.

In the present invention, the fuse layer may be a single metal layer or may include a plurality of metal layers having different melting points.

The metal material forming the metal layer is not particularly limited as long as it has conductivity, and examples thereof include Ni, Cu, Ag, Au, Al, Zn, Rh, Ru, Ir, Pd, Pt, Ni-Au alloy, Ni-P alloy, Ni-B alloy, Sn-Ag alloy, Sn-Cu alloy, Sn-Ag-Cu-Bi-In alloy, Sn-Ag-Cu-Sb alloy, Sn-Cu-Ni-P-Ge alloy, Sn-Cu-Ni alloy, Sn-Ag-Ni-Co alloy, Sn-Ag-Cu-Co-Ni alloy, Sn-Ag-Co-Ni alloy, Sn-Cu-Co-Ni alloy, and the like, Su-Bi-Ag alloy, Sn-Zn alloy, Sn-In alloy, Sn-Cu-Sb alloy, Sn-Fe alloy, Zn-Ni alloy, Zn-Fe alloy, Zn-Co-Fe alloy, Sn-Zn alloy, Pd-Ni alloy, and Sn-Bi alloy.

Preferably, the fuse layer includes: a metal layer formed of a metallic material selected from the group consisting of Ni, Cu, Ag, Au, Al, Zn, Sn, Rh, Ru, Ir, Pd, Pt, Ni-Au alloy, Ni-P alloy and Ni-B alloy, and a metallic material selected from the group consisting of Sn, Sn-Ag alloy, Sn-Cu alloy, Sn-Ag-Cu-Bi-In alloy, Sn-Ag-Cu-Sb alloy, Sn-Cu-Ni-P-Ge alloy, Sn-Cu-Ni alloy, Sn-Ag-Ni-Co alloy, Sn-Ag-Cu-Co-Ni alloy, Su-Bi-Ag alloy, A metal material selected from Sn-Zn alloy and Sn-Bi alloy. More preferably, the fuse layer includes a metal layer made of Ni and a metal layer made of Sn, a Sn — Cu alloy, or a Sn — Bi alloy.

When an excessive current is intended to flow from the conductive metal thin-layer electrode on one main surface toward the conductive metal thin-layer electrode on the other main surface by forming the fuse layer as a plurality of metal layers having different melting points as described above, the excessive current flows intensively through the fuse layer to generate heat, and as a result, first, the metal layer formed of a metal having a relatively low melting point melts. As a result, the current flowing through the metal layer flows to the metal layer formed of the metal having the relatively high melting point, the current flowing through the metal layer increases, and the metal layer formed of the metal having the relatively high melting point is rapidly melted, thereby rapidly and reliably cutting off the excessive current. With such a configuration, even an excessive current that does not greatly exceed the rated current of the fuse layer, for example, an excessive current that is about twice the rated capacity, can be reliably protected, and the function of the protection element as a current interrupting mechanism can be improved.

In one embodiment, the conductive metal thin-layer electrode on the conductive metal foil side of the (ii) conductive metal thin-layer electrode of the protection element may be omitted. In this case, the conductive metal foil also functions as one electrode of the disk-shaped protective element. That is, the conductive metal foil is in contact with the main surface of the layered member, and is directly connected to the conductive metal thin-layer electrode on the second positive electrode cap side through the fuse layer of the disk-shaped protection element. With this configuration, one of the conductive metal thin-layer electrodes can be omitted, and thus the number of components can be reduced and the thickness can be reduced.

In the illustrated embodiment, the second positive electrode cover 18 has an exhaust port 28. This exhaust port 28 is provided, similarly to the exhaust port 26 of the first positive electrode cap 12, for exhausting gas when the gas is generated inside the battery due to an abnormal reaction of the electrolyte solution, the active material, or the like, and the internal pressure of the battery rises to operate the explosion-proof valve.

In the present invention, the second positive electrode cap is formed of a conductive metal. The conductive metal is not particularly limited, but when the sealing member is a sealing member for a lithium ion battery, for example, nickel plated steel is preferable.

In the illustrated embodiment, insulating gaskets 22 are provided around the conductive metal foil 14, the protective element 16, and the second positive electrode cap 18, and on the flange portion 20 of the second positive electrode cap 18. Conductive metal foil 14, protection element 16, second positive electrode cap 18, and insulating gasket 22 are provided as shown in the drawing, and then fixed by caulking portion 24 of first positive electrode cap 12.

In the present invention, as long as the insulating gasket has corrosion resistance against the electrolytic solution and has insulation properties, a commonly used gasket can be used. Examples of the material of the insulating gasket include insulating resins such as polypropylene and polyethylene.

The insulating gasket ensures insulation between the first positive electrode cover, the protection element (specifically, the conductive metal thin-layer electrode on the main surface of the protection element on the second positive electrode cover side in the illustrated embodiment), and the second positive electrode cover. By insulating the first positive electrode cover from the protection element and the second positive electrode cover, it is possible to prevent current from flowing directly from the first positive electrode cover to the second positive electrode cover, in other words, to prevent current from flowing without passing through the fuse layer. With this configuration, the protection element operates to cut off the current flowing from the conductive metal foil to the second positive electrode cap via the protection element, thereby cutting off the current flowing through the sealing body. In addition, the insulating gasket prevents leakage of the electrolyte.

In the sealing body of the present invention, when an excessive current is generated due to some abnormality, the protection element having a fuse function operates to cut off the current. When gas is generated inside the battery and the internal pressure of the battery exceeds a set value, the conductive metal foil serving as an explosion-proof valve operates to discharge the gas to the outside of the battery, thereby preventing an abnormal increase in the internal pressure of the battery.

In one embodiment, in the sealing body of the present invention, the protective element having a fuse function is operated to cut off the current before the conductive metal foil serving as the explosion-proof valve is operated.

The sealing body 10 shown in the figure can be manufactured, for example, in the following manner.

First, disc-shaped first positive electrode cap 12 with caulking portion 24 extended is prepared. An insulating gasket 22 is provided on the inner side of the wall surface of the first positive electrode cover. At this time, the insulating gasket is not provided on the bottom surface of the first positive electrode cap.

Next, the conductive metal foil 14, the protection element 16, and the second positive electrode cap 18 are stacked in this order inside the first positive electrode cap. The conductive metal foil 14 and the protection element 16 may be bonded in advance to form a single member.

Finally, the crimped portion of the first positive electrode cap is bent inward, and the conductive metal foil 14, the protection element 16, the second positive electrode cap 18, and the insulating gasket 22 are crimped and fixed.

In the sealing body of the present invention, first positive electrode cap 12 is in surface contact with conductive metal foil 14, the contact area is large, and the contact portion is pressed by the crimped portion, so that welding for reliably achieving electrical connection between both is not necessary. Therefore, the sealing body of the present invention can be easily manufactured. In the sealing body of the present invention, the conductive metal foil only needs to function as an explosion-proof valve, and therefore, the shape and structure can be simplified as compared with an explosion-proof valve that also functions as a current interrupting mechanism in a conventional sealing body.

In addition, in the sealing body of the present invention, since insulation between the bottom surface portion of the first positive electrode cap and the flange portion of the conductive metal foil is not required, the thickness can be reduced as compared with a conventional sealing body requiring an insulating layer here. Further, since the number of members in the stacking direction of the members of the sealing body can be reduced, variation in thickness can be suppressed, and the load pressure applied to the members can be further stabilized.

The sealing body of the present invention can be suitably applied as a sealing body for a sealed battery, particularly a cylindrical battery, more specifically a cylindrical lithium ion secondary battery. Accordingly, the present invention also provides a sealed battery, particularly a cylindrical battery, specifically a cylindrical lithium ion secondary battery, having the sealing body of the present invention.

Industrial applicability of the invention

The sealing body of the present invention can be used as a sealing body for a sealed battery, for example, a cylindrical sealed battery, specifically, a cylindrical lithium ion secondary battery.

Description of the reference numerals

10 … sealing body

12 … first positive cover

14 … conductive metal foil

16 … protection element

18 … second positive cover

20 … flange part of second positive electrode cover

22 … insulating gasket

24 … caulking portion

26 … air outlet

28 … air vent

100 … sealing body

102 … valve cover

104 … internal gasket

106 … explosion-proof valve

108 … PTC element

110 … positive terminal

112 … connection location