JP6209585B2 - Sealing body - Google Patents

Description

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

  Lithium ion batteries have advantages such as high energy density, high operating voltage, excellent voltage flatness during discharge, low self-discharge, and no memory effect. Suitable as a power source. However, a secondary battery containing an organic solvent such as a lithium ion battery as an electrolyte solution is decomposed due to abnormalities such as overcharge, internal short circuit, or misuse, and gas is generated inside the battery. There was a problem such as an increase in internal pressure.

  For example, as shown in FIG. 1, Patent Document 1 discloses a valve cap 102 having a vent hole, an explosion-proof valve 106 positioned thereon via an internal gasket 104, and the like. A sealed battery having a sealing body 100 composed of a PTC element 108 positioned above and a positive electrode terminal 110 having a vent hole positioned above is disclosed. In a sealed battery having such a sealing body, when the battery internal pressure exceeds a set value, the explosion-proof valve 106 is operated to discharge the gas to the outside of the battery, thereby preventing the battery internal pressure from increasing.

JP-A-11-283588

  However, since the above-described sealing body normally serves as a current path for the explosion-proof valve, in order to ensure the electrical connection between the explosion-proof valve 106 and the valve cap 102, Welding is required. Therefore, there is a problem that a welding process is required at the time of manufacturing the sealing body, and the manufacturing process becomes complicated.

  In addition, the PTC element operates (trips) in an abnormal state to become a high resistance and can interrupt a current flowing therethrough, but a small current (leakage current) can flow even after the operation. However, depending on the type of abnormality, it is required that the circuit opens completely. Therefore, in the conventional sealing body, in order to cut off this minute current, a function as a current cut-off mechanism (CID: Current Interrupt Device) is added to the explosion-proof valve. Therefore, in the sealing body 100 described above, in order to allow the electrical connection between the valve cap 102 and the explosion-proof valve 106 to be interrupted after the operation of the explosion-proof valve, an insulation is provided between the valve cap 102 and the flange portion of the explosion-proof valve 106. An internal gasket 104 is installed. Therefore, there exists a problem that the thickness as the whole sealing body becomes thick by the gasket. In addition, since the number of parts increases, the influence of dimensional (thickness) variation unique to each part increases, and the load pressure applied to the PTC element is not stabilized by caulking, and the withstand voltage characteristic of the PTC element is deteriorated. is there.

  Further, since the explosion-proof valve has both a function as an explosion-proof valve and a function as a current interruption 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.

  Therefore, the problem to be solved by the present invention is to provide a sealing body for a sealed battery that is easy to manufacture and can be further reduced in size.

In the first aspect, the present invention provides a sealing body for a sealed battery,
(1) a first positive electrode cap having a caulking portion and a vent hole;
(2) a conductive metal foil located on the first positive electrode cap;
(3) a protective element located on the conductive metal foil and having a fuse function;
(4) a second positive electrode cap that is located on the protective element and has a vent hole, and the conductive metal foil, the protective element, and the second positive electrode cap are formed by caulking portions of the first positive electrode cap. A sealing body characterized by being fixed is provided.

  In the sealing body of the present invention, since the protective element having the fuse function (3) functions as a current interrupt mechanism, the conductive metal foil may function as an explosion-proof valve. Therefore, the conductive metal foil does not require a complicated shape and structure. Further, 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 arrange an insulating gasket between the conductive metal foil and the first positive electrode cap. Furthermore, since the electrical connection between the conductive metal foil and the first positive electrode cap is ensured by pressing by the caulking portion of the first positive electrode cap in addition to the fact that both are in contact with each other, the conductive metal foil There is no need to weld the foil and the first positive electrode cap.

  In a second aspect, the present invention provides a sealed battery having the sealing body of the present invention.

  The sealing body of the present invention can simplify the shape and structure of the conductive metal foil as an explosion-proof valve by using a protective element having a fuse function as a current interruption mechanism, and the conductive metal foil. There is no need to weld the first positive electrode cap. Thereby, manufacture of a sealing body can be simplified. Furthermore, a more compact sealing body can be provided.

FIG. 1 schematically shows a conventional sealing body for a sealed battery in a sectional view. FIG. 2 schematically shows one embodiment of a sealing body for a sealed battery according to the present invention in a sectional view. FIG. 3 schematically shows the sealing body of FIG. 2 in a plan view.

  Below, the sealing body of this invention is demonstrated in detail with reference to drawings. However, it should be noted that the sealing body of the present invention is not limited to the illustrated embodiment.

  One embodiment of the sealing body of the present invention is schematically shown in FIG. 2 in a sectional view along the thickness direction and in FIG. 3 in a plan view.

  The illustrated sealing body 10 is a sealing body for a cylindrical battery, and a conductive metal foil 14, a protective element 16 having a fuse function, and a second positive electrode cap 18 are sequentially laminated on a first positive electrode cap 12. And an insulating gasket 22 located on the periphery and on the flange portion (outer edge portion) 20 of the second positive electrode cap 18, and these are fixed by a caulking portion 24 located on the edge portion of the first positive electrode cap 12. Yes.

  In the illustrated embodiment, the first positive electrode cap 12 has a gas vent 26 at the center thereof. The gas vent 26 discharges gas to the outside of the battery when gas is generated inside the battery due to an abnormal reaction of the electrolytic solution and / or active material, etc., and the explosion-proof valve is activated due to an increase in battery internal pressure. Provided. Therefore, it is preferable that a protective element having a fuse function does not exist immediately above the gas vent 26. Further, the first positive electrode cap 12 has a caulking portion 24, and another member constituting the sealing body is placed on the first positive electrode cap 12 at a predetermined position, and then the caulking portion 24 is bent inwardly. The member is fixed.

  In the present invention, the first positive electrode cap is formed of a conductive metal. The conductive metal is not particularly limited. For example, when the sealing body is for a lithium ion battery, it is preferably aluminum or an aluminum alloy.

  In the illustrated embodiment, the conductive metal foil 14 is a disk-shaped metal foil and functions as an explosion-proof valve. Moreover, at the normal time, the conductive metal foil 14 prevents the electrolyte from leaking out of the battery through the gas vent.

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

  The thickness of the conductive metal foil is not particularly limited as long as it can function as an explosion-proof valve. A person skilled in the art depends on the structure of the sealing body, particularly the inner diameter of the protective element, so that the explosion-proof valve operates (explodes) when a desired pressure (generally 10 to 15 kgf) is applied. The thickness of the conductive metal foil can be determined as appropriate.

  The conductive metal foil can be easily manufactured by a general metal foil manufacturing method, for example, rolling.

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

In the illustrated embodiment, the protection element 16 is annular.
(I) a layered element 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 element; and (iii) a conductive metal thin layer electrode electrically located on a side surface defining at least one of the through openings. A protective element (disk type protective element) having a fuse layer to be connected. In the illustrated embodiment, for the sake of simplicity, illustration of the conductive metal thin layer electrode located on each main surface of the fuse layer and the layered element is omitted, and the protection element 16 as a whole is illustrated. The disk-type protective element is disclosed in, for example, International Publication No. 2012/118153 (the entire disclosure including the protective element illustrated in the drawings and the manufacturing method thereof is incorporated herein by reference).

  The layered element formed of the insulating resin has at least one through opening. This through-opening extends along the thickness direction of the layered element and penetrates the layered element. When gas is generated inside the battery and the explosion-proof valve is activated, the gas generated inside the battery is transferred to the outside of the battery. The gas vent 26 of the first positive electrode cap and the gas vent 28 of the second positive electrode cap are in gas communication so that the gas can be discharged. The position and number of the through-openings are not particularly limited, but may be one at the center of the layered element, or a plurality of, for example, a circumferential portion of the annular layered element having the center through-opening, for example, Two, three, or four may be provided.

  The insulating resin constituting the layered element is not particularly limited as long as it is an electrically insulating resin. Examples thereof include resins such as polyethylene, polypropylene, polycarbonate, fluorine resin, ABS resin, polycarbonate-ABS alloy resin, PBT resin, and elastomer. In particular, it is preferable to use a resin such as polyethylene or polyvinylidene fluoride.

  The layered element comprises a thin conductive metal layer electrode disposed on the main surface on both sides thereof. The conductive metal thin layer electrode is not particularly limited as long as it is a thin layer of conductive metal (for example, a thickness of about 0.1 μm to 100 μm). For example, copper, nickel, aluminum, gold, etc. And may be formed of a plurality of thin metal layers.

  The layered element in which the conductive metal thin layer electrode is located on each main surface is obtained by co-extruding the insulating resin constituting the layered element together with the metal sheet (or metal foil) constituting the metal thin layer, It can be manufactured by obtaining an extrudate in which an insulating resin is sandwiched between metal sheets (or metal foils). In another embodiment, a layered product of an insulating resin is obtained by, for example, extrusion, the layered product is sandwiched between metal sheets (or metal foils), and these are thermocompression bonded together to obtain a pressed product. You can also Further, in another aspect, the conductive metal thin layer electrode may be formed on the main surfaces on both sides by plating the layered element of the insulating resin with conductive metal. The thus obtained layered elements having conductive metal (such as extrudates or pressure-bonded products) have a large number of insulating resin layered elements having conductive metal thin layer electrodes on both main surfaces. In this state, the layered element can be cut into a predetermined shape and size to obtain a layered element having a single conductive thin layer.

  The form of the layered element is not particularly limited as long as the dimension in the thickness direction is smaller than the other dimensions, preferably considerably small (for example, a sheet-like form). In the illustrated embodiment, the planar shape of the layered element is annular, but is not particularly limited, and is preferably a shape corresponding to the planar shape of the sealing body.

  The protective element has a fuse layer that is located on a side surface that defines at least one of the through-openings and that electrically connects thin conductive metal layer electrodes located on both main surfaces of the layered element.

  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, but preferably includes a plurality of metal layers having different melting points.

  The metal material for forming the metal layer is not particularly limited as long as it is conductive. For example, Ni, Cu, Ag, Au, Al, Zn, Rh, Ru, Ir, Pd, Pt, Ni— Au alloy, Ni-P alloy, Ni-B alloy, Sn, Sn-Ag alloy, Sn-Cu alloy, Sn-Ag-Cu alloy, Sn-Ag-Cu-Bi alloy, Sn-Ag-Cu-Bi-In Alloy, Sn-Ag-Bi-In alloy, Sn-Ag-Cu-Sb alloy, Sn-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, Sn-Zn alloy, Sn-In alloy, Sn-Cu-Sb alloy, Sn-Fe alloy, Zn-Ni alloy, Zn-Fe Alloy, Zn-Co alloy, Zn-Co-Fe alloy , Sn-Zn alloys, Pd-Ni alloy and Sn-Bi alloys.

  The fuse layer is preferably selected from Ni, Cu, Ag, Au, Al, Zn, Sn, Rh, Ru, Ir, Pd, Pt, Ni—Au alloy, Ni—P alloy and Ni—B alloy. One metal layer formed from a metal material, and Sn, Sn-Ag alloy, Sn-Cu alloy, Sn-Ag-Cu alloy, Sn-Ag-Cu-Bi alloy, Sn-Ag-Cu-Bi-In Alloy, Sn-Ag-Bi-In alloy, Sn-Ag-Cu-Sb alloy, Sn-Sb alloy, Sn-Cu-Ni-P-Ge alloy, Sn-Cu-Ni alloy, Sn-Ag-Ni-Co It includes another metal layer formed from a metal material selected from alloys, Sn-Ag-Cu-Co-Ni alloys, Su-Bi-Ag alloys, Sn-Zn alloys and Sn-Bi alloys. More preferably, the fuse layer includes a metal layer formed of Ni and a metal layer formed of Sn, Sn—Cu alloy, or Sn—Bi alloy.

  Thus, by making the fuse layer into a plurality of metal layers having different melting points, an excess current is generated from the conductive metal thin layer electrode on one main surface to the conductive metal thin layer electrode on the other main surface. When an attempt is made to flow, excessive current flows intensively through the fuse layer and generates heat. As a result, first, a metal layer formed of a metal having a relatively low melting point is melted. As a result, the current flowing through the metal layer flows into the metal layer formed from the metal having a relatively high melting point, and the current flowing therethrough increases to form the metal from the metal having a relatively high melting point. As the metal layer melts quickly, excess current is quickly and reliably interrupted. With such a configuration, it is possible to provide reliable protection against an excess current that does not greatly exceed the rated current of the fuse layer, for example, an excess current that is about twice the rated capacity. The function as a blocking mechanism can be improved.

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

  In the illustrated embodiment, the second positive electrode cap 18 has a gas vent port 28. In the same way as the gas vent port 26 of the first positive electrode cap 12, the gas vent port 28 generates gas inside the battery due to an abnormal reaction of the electrolyte and / or the active material, and the internal pressure of the battery rises to increase the explosion-proof valve. It is provided to discharge gas when activated.

  In the present invention, the second positive electrode cap is formed of a conductive metal. Although this electroconductive metal is not specifically limited, For example, when a sealing body is for lithium ion batteries, it is preferable that it is nickel plating steel.

  In the illustrated embodiment, an insulating gasket 22 is installed 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. The conductive metal foil 14, the protective element 16, the second positive electrode cap 18, and the insulating gasket 22 are installed as shown in the figure, and then fixed by the caulking portion 24 of the first positive electrode cap 12.

  In the present invention, the insulating gasket is resistant to the electrolytic solution, and generally used gaskets can be used as long as they are insulating. For example, examples of the material for the insulating gasket include an insulating resin such as polypropylene and polyethylene.

  The insulating gasket includes a first positive electrode cap, a protective element (specifically, in the illustrated embodiment, a conductive metal thin layer electrode on the main surface of the protective element on the second positive electrode cap side), and a second positive electrode cap. Ensure insulation between. By insulating between the first positive electrode cap and the protective element and the second positive electrode cap, a current flows directly from the first positive electrode cap to the second positive electrode cap. In other words, a current flows without passing through the fuse layer. This can be prevented. By adopting such a configuration, it is possible to block the current flowing through the sealing body by operating the protection element and blocking the current flowing from the conductive metal foil to the second positive electrode cap via the protection element. become. The insulating gasket prevents electrolyte leakage.

  In the sealing body of the present invention, when an overcurrent occurs due to some abnormality, a protection element having a fuse function is activated to cut off the current. Also, if gas is generated inside the battery and the internal pressure of the battery exceeds the set value, the conductive metal foil as an explosion-proof valve is activated and the gas is discharged outside the battery, causing the internal pressure of the battery to become abnormal. Prevent it from rising.

  In one aspect, in the sealing body of the present invention, the protective element having a fuse function is activated and the current is interrupted before the conductive metal foil as the explosion-proof valve is activated.

The illustrated sealing body 10 can be manufactured as follows, for example.
First, the dish-shaped first positive electrode cap 12 in which the caulking portion 24 is extended is prepared. An insulating gasket 22 is installed inside the wall surface of the first positive electrode cap. At this time, no insulating gasket is provided on the bottom surface of the first positive electrode cap.
Next, the conductive metal foil 14, the protective element 16, and the second positive electrode cap 18 are sequentially laminated inside the first positive electrode cap. The conductive metal foil 14 and the protection element 16 may be bonded in advance to form one component.
Finally, the caulking portion of the first positive electrode cap is bent inward, and the conductive metal foil 14, the protective element 16, the second positive electrode cap 18, and the insulating gasket 22 are caulked and fixed.

  In the sealing body of the present invention, the first positive electrode cap 12 and the conductive metal foil 14 are in contact with each other, the contact area is large, and the contact portion is pressed by the caulking portion. No welding is required to ensure Therefore, the sealing body of the present invention can be easily produced. In the sealing body of the present invention, the conductive metal foil only needs to have a function as an explosion-proof valve. Therefore, compared with the explosion-proof valve that also functions as a current interrupting mechanism in the conventional sealing body, the shape and structure are the same. It becomes possible to simplify.

  Moreover, since the sealing body of the present invention does not require insulation between the bottom surface portion of the first positive electrode cap and the flange portion of the conductive metal foil, it is compared with the conventional sealing body that requires an insulating layer there. Thus, the thickness can be reduced. In addition, since the number of parts in the stacking direction of the parts of the sealing body can be reduced, variations in thickness can be suppressed, and the load pressure applied to the parts can be further stabilized.

  The sealing body of the present invention can be suitably used as a sealing body of a sealed battery, particularly a cylindrical battery, specifically, a cylindrical lithium ion secondary battery. Therefore, the present invention also provides a sealed battery having the sealing member of the present invention, particularly a cylindrical battery, specifically, a cylindrical lithium ion secondary battery.

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

DESCRIPTION OF SYMBOLS 10 ... Sealing body 12 ... 1st positive electrode cap 14 ... Conductive metal foil 16 ... Protection element 18 ... 2nd positive electrode cap 20 ... Flange part of 2nd positive electrode cap 22 ... Insulating gasket 24 ... Caulking part 26 ... Gas vent 28 ... Gas vent 100 ... Sealing body 102 ... Valve cap 104 ... Internal gasket 106 ... Explosion-proof valve 108 ... PTC element 110 ... Positive electrode terminal 112 ... Connection location

Claims (11)

A sealing body for a sealed battery,
(1) a first positive electrode cap having a caulking portion and a vent hole;
(2) a conductive metal foil located on the first positive electrode cap;
(3) a protective element located on the conductive metal foil and having a fuse function;
(4) a second positive electrode cap that is located on the protective element and has a vent hole, and the conductive metal foil, the protective element, and the second positive electrode cap are formed by caulking portions of the first positive electrode cap. Sealing body characterized by being fixed. A protective element having a fuse function
(I) a layered element 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 element; and (iii) a conductive metal thin layer electrode electrically located on a side surface defining at least one of the through openings. The sealing body according to claim 1, which is a protection element having a fuse layer to be connected.   Of the above (ii) conductive metal thin layer electrode, the conductive metal thin layer electrode on the above (2) conductive metal foil side is omitted, and the other conductive metal thin layer electrode and conductive metal foil are the above ( The sealing body according to claim 2, wherein the sealing body is directly connected by a fuse layer.   The sealing body according to claim 2 or 3, wherein the fuse layer includes a plurality of metal layers having different melting points.   The sealing body according to any one of claims 2 to 4, wherein the fuse layer includes a metal layer formed of Ni and a metal layer formed of Sn, Sn-Cu alloy, or Sn-Bi alloy.   The sealing body in any one of Claims 1-5 whose electroconductive metal foil is aluminum foil.   The sealing body in any one of Claims 1-6 which is an object for cylindrical batteries.   The sealing body in any one of Claims 1-7 which is an object for lithium ion secondary batteries.   A sealed battery comprising the sealing body according to claim 1.   The sealed battery according to claim 9, which is a cylindrical battery.   The sealed battery according to claim 9 or 10, which is a lithium ion secondary battery.

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