WO2012118153A1

WO2012118153A1 - Protective element

Info

Publication number: WO2012118153A1
Application number: PCT/JP2012/055252
Authority: WO
Inventors: 久薄井; 新田中
Original assignee: タイコエレクトロニクスジャパン合同会社
Priority date: 2011-03-03
Filing date: 2012-03-01
Publication date: 2012-09-07
Also published as: TW201241858A; KR20170116202A; JPWO2012118153A1; KR20140021593A; CN103503109A; TWI549154B

Abstract

In order to provide a protective element that is capable of providing protection against excess currents while also allowing larger currents to flow, this protective element comprises: a layered element, which is formed by an insulating resin, and has at least one pass-through opening; thin conductive metal layers positioned on each main surface of the layered element; and a fuse layer, which is positioned on the sides that define the at least one pass-through opening, and electrically connects the thin conductive metal layers.

Description

Protective element

The present invention relates to a protective element for protecting an electric device, and more particularly to a protective element for protecting an electric element or circuit included in the electric device. For example, the present invention relates to a protection element that cuts off a current flow when an excessive current flows in an electric device such as a secondary battery, that is, an overcurrent protection element.

A thermal fuse element, a current fuse element, a polymer PTC element, or the like is used as a protective element that cuts off the flow of excess current when a cylindrical lithium ion secondary battery is charged or discharged. Among these, since the polymer PTC element can be arranged by being incorporated in a sealing plate of a secondary battery, it is particularly useful in that a battery pack constituted by a large number of secondary batteries becomes compact.

However, a commercially available PTC element cannot pass a large current (for example, a current of 20 A). Further, the PTC element has a recoverability that becomes low resistance when the abnormality is removed and the temperature is lowered. However, such a recoverability may cause a problem depending on the application. For example, when a PTC element is used in a cylindrical lithium ion secondary battery cell that is used in parallel, the cell continues to generate heat unless the short-circuited cell using the PTC element is removed, resulting in a battery cell. May burst.

Considering such problems, it has been proposed to use a spacer instead of the PTC element inside the sealing plate, for example, in the cylindrical lithium ion secondary battery cell (see Non-Patent Document 1 below). . However, when a spacer is used, there is a problem that protection against excess current cannot be secured.

Therefore, a problem to be solved by the present invention is to provide a protective element that can provide protection against excess current while allowing a larger current to flow.

In the first aspect, the present invention provides:
A layered element formed of insulating resin and having at least one through opening;
A conductive metal thin layer located on each main surface of the layered element, and a fuse layer located on a side surface defining at least one of the through openings and electrically connecting the conductive metal thin layer A protective element is provided.

In a second aspect, the present invention provides an electric device, for example, a secondary battery, comprising the protective element of the present invention as described above and below. More specifically, the present invention provides a secondary battery cell, a secondary battery cell assembly or a secondary battery pack that is a combination thereof.

The protective element of the present invention comprises a layered element formed of an insulating resin, and this layered element has at least one through opening. The opening extends along the thickness direction of the layered element and penetrates the layered element, and the cross-sectional shape in the direction perpendicular to the thickness direction is not particularly limited, but is circular, for example. Is preferred. In this case, the through opening is a cylindrical space. However, other shapes, such as squares, rhombuses, rectangles, and ellipses may be used. The number of through openings is at least one. That is, it may be one, two or more, and may be two, three, four, five, for example, but can be appropriately selected according to the degree of protection required for the protection element. In the case of having one through opening, the through opening is preferably located at the center of the layered element, more specifically at the center of the cross-sectional shape in the direction perpendicular to the thickness direction.

The insulating resin constituting the layered element is not particularly limited as long as it is an electrically insulating resin. For example, resins such as polyethylene, polypropylene, polycarbonate, and fluorine resin can be exemplified. In particular, it is preferable to use a resin such as polyethylene or polyvinylidene fluoride. Such a resin has the same flexibility as the polymer used for the polymer PTC element, and the protective element of the present invention is used instead of the polymer PTC element. Can be incorporated into the sealing plate of the secondary battery cell, and is generally advantageous in that it can be used reliably in electric devices. In another aspect, the protective element of the present invention can be used in place of the spacer used inside the sealing plate of the secondary battery cell described above, in which case the protective element is used as a washer. be able to.

The layered element comprises a thin conductive metal layer disposed on each main surface thereof, that is, on the main surfaces on both sides thereof. The thin metal layer is not particularly limited as long as it is a thin layer of conductive metal (for example, a layer having a thickness of about 0.1 μm to 100 μm). For example, copper, nickel, aluminum, gold, etc. It can be made of metal.

The layered element in which the conductive metal thin layer is located on each main surface is obtained by, for example, extruding an 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 (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. Such an extrudate (or pressure-bonded product) is a state in which a large number of layered elements of insulating resin having conductive metal thin layers on both main surfaces are gathered adjacent to each other. A single layered element having a conductive thin layer on each main surface can be obtained by cutting into a predetermined shape and size.

Furthermore, in another aspect, a conductive metal thin layer may be formed on the main surfaces on both sides by plating a conductive metal on the insulating resin layered element. In this case as well, it is preferable to obtain the aggregated state as described above and then divide it into individual layered elements.

Thus, in the case of plating, the layered element is preliminarily separated from the layered element by extruding or thermocompressing another metal layer, particularly preferably a metal foil, on its main surface, for example as described above. It is particularly preferable to keep it in close contact. In this case, it is preferable to form a thin conductive metal layer by plating on the other metal layer. When the conductive metal thin layer is formed by plating in this way, it is advantageous in that the plating layer as the conductive metal thin layer can be in close contact with another metal layer that is already in close contact with the layered element. For example, the protection element of the present invention has a nickel foil as another metal layer on both principal surfaces of the layered element, and has a thin conductive metal layer and a fuse layer formed by nickel plating. That is, it is advantageous in that the conductive metal thin layer and the fuse layer can be formed simultaneously.

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, or preferably considerably small (for example, a sheet-like form). The planar shape of the layered element (the figure when the layered element is viewed from directly above, for example, the contour shape of the protective element shown in FIG. 2, and thus the shape of the main surface) or the sectional shape in the direction perpendicular to the thickness direction of the layered element Are preferably geometrically line-symmetrical and / or point-symmetrical shapes, for example, circular, square, rectangular, rhombus, annular (especially annular, so-called donut-shaped), and the like.

Among them, the layered element is preferably annular, particularly annular. In the case of an annular shape, the central opening, for example, the central circular opening in the case of an annular shape, may be the through opening of the present invention. Further, the layered element has one or more additional through openings, for example, through holes having a circular cross section, at a portion between the inner circumference and the outer circumference defining the ring shape (for example, an intermediate portion thereof). It's okay. Thus, the layered element has at least one through opening.

The protective element of the present invention has a fuse layer located on a side surface that defines at least one of such through openings. The fuse layer electrically connects the thin conductive metal layers located on the main surfaces on both sides of the layered element, and the thin conductive metal layer on one main surface to the thin conductive metal layer on the other main surface. When excess current is about to flow towards the fuse layer, the excess current flows through the fuse layer intensively, and as a result, it melts and opens the circuit, thereby blocking such current flow (so-called fuse Function). Such a fuse layer is formed on a side surface defining at least one through opening. More specifically, as long as the thin conductive metal layers on both sides can be electrically connected, a fuse layer may be formed on at least a part of such a side surface. Is preferred. The formation method is not particularly limited, but it is particularly preferable to form the conductive metal by plating (for example, electrolytic plating or electroless plating), for example, by nickel plating. The thickness of the fuse layer can be controlled by plating conditions, but is preferably 0.001 to 0.02 mm, for example.

When a single through opening having a fuse layer on the side is provided, the layered element is circular or other suitable flat plate shape without holes, and its central portion (planar shape is circular (ie, disk shape) It is preferable to provide a through opening (also referred to as “center through opening”) in such a layered element where such a central portion exists). As a result, the layered element has a strictly annular shape. The current flowing through the thin conductive metal layer on one main surface of the layered element having such an annular shape flows toward one end of the through opening, and then passes through the fuse layer to form the through opening. Flows radially from the other end of the part over the thin conductive metal layer on the other main surface of the layered element.

Thus, in the aspect in which one through opening is provided in the layered element, a larger through opening is formed in the central part of the annular element as compared with an aspect in which a plurality of through openings to be described in detail later is provided. The opening is preferably provided, and a fuse layer is provided on the side surface of the through opening. Since such a protective element can reduce the resistance value, it can be suitably used when a large-capacity current (preferably a current larger than 20 A, for example, a current of 30 to 40 A or larger, such as 50 A) is passed. Moreover, since only one through opening is provided, the manufacture of the protective element is simplified.

In a preferred embodiment, the layered element has an annular shape defined by an inner periphery 30 and an outer periphery 34, as shown in FIG. The diameter of the circle defining the inner circumference of the layered element is preferably 6 to 10 mm, for example, and the diameter of the circle defining the outer circumference is preferably 13 to 17 mm, for example. As a protection element when a current of 30 to 40 A is passed, it is preferable that the diameter of the inner circumference circle is 6.5 mm, for example, and the thickness of the fuse layer is 0.01 mm, for example.

When providing a plurality of through openings, it is preferable to arrange the through openings so that the current passing through the layered element flows through the fuse layer of each through opening as evenly as possible. For example, in a circumferential portion of an annular layered element having a central through opening (ie, a body portion of a layered element defined by an inner circumference and an outer circumference), a through opening having the same cross-sectional shape and size (“ In this case, it is preferable to provide the through openings at an equal angle with respect to the center of the inner circumferential circle that defines the ring. For example, two through openings are provided every 180 °, three every 120 °, four every 90 °, and six every 60 °. However, depending on the conditions of use of the protective element, the layered element may have only one peripheral through opening. Therefore, the number of circumferential through openings may be 1 to 6, for example.

When the diameter of the inner circumferential circle defining the toroidal layered element, i.e. the cross-sectional circle of the central through opening, is equal to or smaller than the diameter of the other through openings, i.e. the peripheral through openings A fuse layer may also be provided on the side surface defining such a central through opening. Conversely, when the diameter of the cross-sectional circle of the central through opening is larger than the diameter of the cross-sectional circle of the peripheral through opening, it is preferable not to provide a fuse layer on the side surface that defines the central through opening.

Whether or not the fuse layer is provided in the central through opening as described above is determined by whether or not the current flowing through the fuse layer provided in each through opening of the protective element is substantially equal. Briefly, when the central through opening has a larger circular cross section than the peripheral through opening, if a fuse layer is provided in the central through opening, substantially the majority of the current flowing through the protective element is likely to flow through the fuse layer, Since it is difficult for current to flow through the fuse layer provided in another through opening having a smaller circular cross section, the meaning of providing the fuse layer in the other through opening is reduced.

In one preferred embodiment, the layered element is an annular element defined by an outer periphery and an inner periphery, the inner peripheral surface defines the through opening as a central through opening, and another through opening is layered It may exist as a peripheral through opening through the interior of the element, ie, between the inner and outer perimeters that define the layered element (ie, the portion of the insulating resin that defines the layered element). Accordingly, in this case, the layered element has a central through opening (one) defined by the inner circumference and at least one through opening (corresponding to the peripheral through opening described above) penetrating through the body part of the layered element. Exists.

In this embodiment, the fuse layer exists on the side surface (that is, the wall) that defines the peripheral through opening. When the diameter of the central through opening is not much different from the diameter of the peripheral through opening and a fuse layer exists in the central through opening, current flows in the fuse layer as well as the fuse layer in the peripheral through opening. If expected, a fuse layer may also be provided in the central through opening. When the diameter of the central through opening is larger than the diameter of the peripheral through opening and a fuse layer exists in the central through opening, a much larger amount of current flows through the fuse layer than the fuse layer of the peripheral through opening. In the case where it is expected, there is no point in providing a fuse layer in the peripheral through opening, and therefore no fuse is provided in the central through opening.

Therefore, in one aspect of a protective element having an annular layered element having a plurality of through openings, for example, an annular layered element, the central through opening does not have a fuse layer and is arranged circumferentially around it. And a plurality of peripheral through openings. The circumference in which the peripheral through-opening is provided is usually preferably single, but in some cases, it may be a multiple circumference, for example, a double circumference or a triple circumference. As described above, in the aspect in which the fuse layer is provided only in the peripheral through opening, the resistance value of the protection element can be controlled according to the number of peripheral through openings provided. Basically, when the number of peripheral through openings is increased, the resistance value is decreased. Conversely, when the number is decreased, the resistance value is increased. Accordingly, there is an advantage that the resistance value of the protection element can be easily and precisely changed by simply changing the number of through openings provided, as compared with the above-described embodiment in which the fuse layer is provided only in the central through opening.

When the layered element is ring-shaped, for example annular, the peripheral through-opening is preferably located in contrast to the center of the layered element. When there are a plurality of peripheral through openings, for example, the center of the annular element, that is, the figure defining the inner circumference, for example, 2 to 12, preferably 4 to 10, more preferably the same angle around the center of the circle. 5-9, particularly preferably 6-8, eg 2 every 180 °, 3 every 120 °, 4 every 90 °, 6 every 60 °, 8 every 45 °, 40 It may be configured so that there are 9 pieces per degree and 10 pieces every 36 degrees.

In a specific embodiment, the diameter of the central through opening (without the fuse layer) is 6 to 10 mm, and the diameter of the cross-sectional circle around the peripheral through opening (with the fuse layer) is 0.2 to 1 mm. In such an embodiment, the outer diameter of the layered element is preferably 13 to 17 mm, for example. For example, four protective through elements having a diameter of 0.6 mm are provided as protective elements when a current of 20 to 30 A is passed, and the thickness of the fuse layer is preferably 0.01 mm, for example.

In any embodiment, the through-opening portion preferably has a circular cross-sectional shape (that is, a cross-sectional shape perpendicular to the thickness direction of the layered element), but may have any appropriate other cross-sectional shape. It may preferably have a generally circular cross section. In another aspect, a square, a rectangle, a rhombus, a triangle, etc. may be sufficient. In that case, the above-mentioned diameter corresponds to the equivalent diameter of another cross-sectional shape.

The fuse layer provided on the side surface (or peripheral surface) that defines the through opening electrically connects the main surfaces on both sides of the layered element, and excess current flows from one main surface to the other main surface. In such a case, as a result of excessive current flowing through the fuse layer in a concentrated manner, it melts, thereby having a function of interrupting such current flow. The material constituting such a fuse layer is a conductive material, in particular a conductive metal layer. For example, the fuse layer is preferably formed of a thin layer of metal such as copper, nickel, aluminum, or gold. The fuse layer is particularly preferably formed by plating a metal constituting the fuse layer.

Therefore, the cross-sectional shape of the through-opening, the size of the through-opening (usually the diameter), and the length of the through-opening along the thickness direction of the layered element so as to melt according to the assumed excess current amount Various factors such as the material of the fuse and the thickness of the layer, and the number and arrangement of the through openings are selected, and the numerical values are selected in a predetermined manner. This selection can be made by those skilled in the art with respect to these factors, for example by trial and error.

In one preferred embodiment, the conductive metal thin layer and the fuse layer are integrally formed by conductive metal plating, more preferably by nickel plating. In this case, it is advantageous that these layers can be formed simultaneously and integrally by plating a layered element having a through opening with such a metal. That is, the fuse layer and the conductive metal thin layer are formed of the same type of metal. As the plating method, electrolytic plating or electroless plating can be used.

In a particularly preferred embodiment, there is a metal foil, preferably a nickel foil, which is in close contact with the layered element, between the main surface of the layered element and the conductive metal thin layer. In this case, there is an advantage that the conductive metal thin layer formed as the plating layer can be in close contact with the metal foil, and as a result, the conductive metal thin layer is firmly bonded to the layered element via the metal foil.

The protection element of the present invention includes a first electric element (for example, a secondary battery) and a second electric element (for example, a charger) as another electric element in order to protect a circuit to be protected or an electric element constituting the circuit. Between the two, so that one of the thin conductive metal layers is in direct or indirect contact with the first electrical element and the other conductive The thin metal layer is in direct or indirect contact with the second electrical element. Accordingly, the present invention also provides an electrical device comprising the protection element of the present invention and the circuits and / or electrical elements electrically connected thereby.

The protection element of the present invention has a thin conductive metal layer on the main surfaces on both sides of the layered element, and allows a large current to flow by electrically connecting them with the fuse layer, but also an excess current. As a result, excessive current flows intensively in the fuse layer, so that the fuse layer is melted and the circuit is cut off, whereby the flow of excess current can be cut off.

FIG. 1 schematically shows a protection element of the present invention in a sectional view along the thickness direction. FIG. 2 schematically shows the protection element shown in FIG. 1 in a plan view. FIG. 3 schematically shows a protective element according to another aspect of the present invention in a cross-sectional view along the thickness direction. FIG. 4 schematically shows the protection element shown in FIG. 3 in a plan view.

The protection element of the present invention will be described in more detail with reference to the drawings. FIG. 1 schematically shows one embodiment of the protection element of the present invention in a cross-sectional view along the thickness direction (a portion appearing as a cut surface is indicated by A), and FIG. Is schematically shown in a plan view (that is, when the protective element is viewed from above as shown by an arrow B in FIG. 1).

The illustrated protection element 10 is formed of an insulating resin, and includes at least one through opening, in the illustrated embodiment, two through openings, a central through opening 12 having a circular cross section and a peripheral through opening 14 having a circular cross section. And having an annular layered element 16. It has thin conductive metal layers 22 and 24 located on the

major surfaces

18 and 20 on both sides of the layered element 16. In the illustrated embodiment, there are

other metal layers

26 and 28 between the layered element 16 and the thin conductive metal layers 22 and 24.

In the illustrated embodiment, there is no fuse layer on the inner circumference 30 of the ring, that is, on the inner side surface of the ring, which defines the central through opening 12. In the illustrated embodiment, a fuse layer 40 is present on a circumferential side 38 that defines a peripheral through opening 14 located in the body portion 36 of the layered element between the inner periphery 30 and the outer periphery 34 of the annulus.

In the illustrated embodiment, only one peripheral through opening 14 having a fuse layer 40 is provided in the middle of the body portion 36 along a diameter (shown in broken lines in FIG. 2) that passes through the center O of the layered element. However, such a peripheral through opening may be provided on the opposite side along the diametrical direction. In that case, two peripheral through openings are provided around the center O every 180 °. In yet another aspect, the peripheral through-openings having preferably 3 to 12, more preferably 4 to 10, and particularly preferably 6 to 8 fuse layers are equiangular with respect to the center O of the circle. For example, peripheral through openings having three fuse layers every 120 °, four every 90 °, six every 60 °, or eight fuse layers every 45 ° may be provided at an equal angle.

In the illustrated embodiment, since the diameter of the central through opening 12 is much larger than the diameter of the peripheral through opening 14, there is no fuse layer on the side surface of the inner periphery 30 of the ring, but the central through opening When the diameter of the part is equal to or smaller than the diameter of the peripheral through opening, a fuse layer may be provided on the side surface of the inner periphery 30 of the ring as necessary. In addition, in a certain aspect, when a convex portion corresponding to the central through opening is provided in the electrical device in which the protection element is to be disposed, such a convex portion is fitted into a large diameter portion of the central through opening. In some cases, the protective element can be positioned on the electric device. For example, the protective element can be positioned on the sealing plate by providing such a convex portion on the sealing plate of the secondary battery cell and fitting the convex portion into the central through opening.

In another aspect, the layered element 16 does not have a central through-opening 12 (and thus the layered element is disk-shaped) and has only at least one peripheral through-opening 14 that has a fuse layer 40. You can do it.

Protective element 10 'according to still another embodiment of the present invention is shown in FIGS. 3 and 4 in the same manner as FIGS. In addition, the same code | symbol is used about the same element as FIG. 1 and FIG. In the illustrated embodiment, the layered element 16 does not have the peripheral through-opening 14 that the protection element 10 of FIG. 1 has, but has only the central through-opening 12, which has the fuse layer 32.

The protective element of the present invention shown in FIGS. 1 and 2 was manufactured. Therefore, the protection element 10 having only the fuse layer 40 and not including the fuse layer 32 included in the protection element 10 ′ of FIG. 3 was manufactured. However, four peripheral through openings 14 were formed at equal angles around the center O in a circumferential shape.

First, a sheet of insulating resin (made of polyethylene, thickness 0.3 mm, corresponding to the layered element 16) is prepared, and nickel foil (thickness: 22 μm, corresponding to the other metal layers 26 and 28) is provided on both sides thereof. These were placed and pressed together under heating to obtain a pressure-bonded product in which nickel foil was attached to both main surfaces of the sheet of insulating resin.

A through-hole having a diameter of 0.6 mm (corresponding to the peripheral through-opening 14) was formed at a predetermined location of the pressure-bonded product, and then the pressure-bonded material was subjected to nickel plating by an electrolytic method. The thickness of the nickel layer (corresponding to the thin conductive metal layers 22 and 24) formed by plating was about 0.01 mm. Next, the annular element was punched out from the pressure-bonded article, and the protection element 10 of the present invention was obtained in which the four through holes were positioned at predetermined positions around the center of the annular element at every 90 °.

The diameter of the outer circumferential circle 34 of the obtained annular element was 15 mm, and the diameter of the inner circumferential circle 30 (that is, the diameter of the central through opening) was 6.4 mm. This annular element has nickel foil functioning as another

metal layer

26 and 28 on both main surfaces of the insulating resin layer 16 as a layered element, and four peripheral penetrations in the middle part of the body part 36 of the annular part. An opening 14 was provided. Further, the annular element had a plating layer as the conductive

thin metal layers

22 and 24 on the nickel foil, and a plating layer functioning as the fuse layer 40 on the inner peripheral surface defining the peripheral through opening. .

A predetermined current (20 A) is passed through the protective element of the present invention from one conductive metal thin layer 22 to the other conductive metal thin layer 24, and the conductive metal thin layer 22 of the protective element 10 minutes later. The surface temperature rise was measured. Moreover, the current interruption time (that is, the time until the fuse layer was blown when a current of 100 A was passed) as a fuse of the protective element was measured.

As a result, the surface temperature increase was 10 ° C. or less at any location, and the current interruption time was 0.1 second or less.

The protective element of the present invention shown in FIGS. 3 and 4 was manufactured. Therefore, the protective element 10 ′ having only the fuse layer 32 around the central through opening without having the peripheral through opening was manufactured. In addition, in the manufacturing method, after forming the opening corresponding to the center through-opening in the press-bonded product, a fuse layer is formed by plating, and then the protective element 10 ′ is obtained by punching out the annular element. Was carried out in the same manner as in Example 1. The diameter of the central through opening was 6.5 mm, and the thickness of the fuse layer was 0.1 mm.

A predetermined current (30 to 40 A) is passed from one conductive metal thin layer 22 to the other conductive metal thin layer 24 through the obtained protective element of the present invention, and the conductive metal thin layer of the protective element after 10 minutes. 22 surface temperature rises were measured. Moreover, the current interruption time (that is, the time until the fuse layer was blown when a current of 100 A was passed) as a fuse of the protective element was measured.

As a result, the increase in surface temperature was 10 ° C. or less at any location, and the current interruption time was about 0.1 seconds.

From these results, it can be seen that the protection element of the present invention can provide protection against excess current while allowing a larger current to flow. Therefore, in the protection element of the present invention, when the current value that can be steadily passed is extremely increased, for example, in a cylindrical lithium ion secondary battery cell, a nickel washer incorporated in a sealing plate, nickel plating on a stainless material It can also be used as an alternative to washers that have been subjected to. In this case, since the protective element has a layered element formed of an insulating resin, the function as a washer is improved by the elasticity of the resin. Accordingly, the present invention also provides a washer having the features of the protective element of the present invention described above.

10, 10 '... protective element, 12 ... central through opening, 14 ... peripheral through opening,
16 ... layered element, 18, 20 ... main surface, 22, 24 ... thin conductive metal layer,
26, 28 ... another metal layer, 30 ... inner circumference, 32 ... fuse layer, 34 ... outer circumference,
36 ... main body part, 38 ... side surface, 40 ... fuse layer.

Claims

A layered element formed of insulating resin and having at least one through opening;
A conductive metal thin layer located on each main surface of the layered element, and a fuse layer located on a side surface defining at least one of the through openings and electrically connecting the conductive metal thin layer A protective element.
2. The protective element according to claim 1, wherein the thin conductive metal layer and the fuse layer are integrally formed by plating a metal.
The protective element according to claim 2, wherein the metal to be plated is nickel.
The protective element according to claim 2, further comprising a metal foil positioned between the layered element and the conductive metal thin layer.
The protective element according to claim 4, wherein the metal foil is a nickel foil.
The layered element is an annular element defined by an inner peripheral surface and an outer peripheral surface, and has one through opening defined by the inner peripheral surface. Protection element.
The laminar element is an annular element defined by an inner peripheral surface and an outer peripheral surface and having at least two through openings, the through openings comprising a central through opening and an inner periphery defined by the inner peripheral surface. 6. The protection element according to claim 1, wherein the protective element is at least one peripheral through opening located between the surface and the outer peripheral surface, and the peripheral through opening has a fuse layer.
The protective element according to claim 7, wherein in the layered element, 6 to 8 peripheral through openings are provided at an equal angle around the central through opening.
The protective element according to any one of claims 1 to 8, wherein the layered element has an annular shape.
An electric device comprising the protective element according to any one of claims 1 to 9.
A secondary battery cell comprising the protective element according to any one of claims 1 to 9.
A layered element formed of insulating resin and having at least one through opening;
A conductive metal thin layer located on each main surface of the layered element, and a fuse layer located on a side surface defining at least one of the through openings and electrically connecting the conductive metal thin layer A washer.