JP3754793B2 - Temperature fuse and temperature fuse mounting structure for secondary battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a temperature fuse, and more particularly to a temperature fuse used by being attached to a sealed secondary battery.
[0002]
[Prior art]
Recently, a large-capacity battery such as a lithium ion battery or a nickel metal hydride battery is being used as a power source for portable electronic devices.
FIG. 6 shows an example of these secondary batteries, in which a spiral wound body E of a positive electrode p and a negative electrode n via a separator s is accommodated in a negative electrode can 51 ′, and the bottom surfaces of the negative electrode n and the negative electrode can 51 ′. Are electrically connected to each other, a positive electrode collector electrode 53 ′ is disposed in the upper end of the negative electrode can 51 ′, the positive electrode 53 ′ is electrically connected to the collector electrode 52 ′, and a safety valve is connected to the upper end of the negative electrode can 51 ′. A positive electrode lid 54 ′ with a gas discharge hole 541 ′ is sealed with a gasket 55 ′, and the central recess 521 of the safety valve 52 is electrically connected to the positive electrode collecting electrode 53.
Thus, when the internal pressure rises abnormally, the safety valve 52 ′ is opened, gas is released from the gas discharge hole 541 ′ of the positive electrode lid 54 ′, and electrical conduction between the safety valve 52 ′ and the positive electrode collector electrode 52 ′ is interrupted. Is done.
[0003]
The above lithium ion battery, nickel metal hydride battery, etc. have a large capacity, a considerably large current flows at the time of charging or discharging, and an overcurrent flows at the time of failure of the charger or main device, causing abnormal heat generation. There is.
Conventionally, in response to such abnormal heat generation, a temperature fuse is attached to the secondary battery, and when the abnormal heat generation occurs, the temperature fuse is blown to stop charging or discharging without waiting for the operation of the safety valve. It is known. In this case, there is an advantage that the discharge and scattering of the electrolyte solution of the secondary battery can be prevented, and the surrounding electrolyte solution can be avoided.
[0004]
[Problems to be solved by the invention]
However, conventionally, the temperature fuse is attached to the outer surface of the cathode can of the secondary battery, and the storage space for the secondary battery has to be increased, which is disadvantageous for miniaturization of portable electronic devices.
[0005]
An object of the present invention is to provide a thin temperature fuse that can be attached to a secondary battery without increasing the accommodation space of the secondary battery, and a structure for attaching the temperature fuse in the secondary battery.
[0006]
[Means for Solving the Problems]
The temperature fuse according to the present invention accommodates a low melting point soluble alloy grain and a flux in the hole of the insulating plate through which the hole is formed, and fixes the electrode to both surfaces of the insulating plate. The structure is characterized in that the molten alloy grains are brought into contact with each other, and the holes of the insulating plate are formed into small and large diameter multistage holes for holding the low melting point soluble alloy grains .
A temperature fuse mounting structure in a secondary battery according to the present invention is characterized in that the temperature fuse is held between a safety valve peripheral end and a positive electrode cover peripheral end of the secondary battery. It is.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view showing an example of a temperature fuse according to the first aspect.
In FIG. 1, reference numeral 1 denotes an insulating plate, for example, a plastic plate, a ceramic plate, and the like, and an intermediate plate 11 having a small-diameter hole 111 and upper and lower plates 12 and 12 having a large-diameter hole 121 are laminated by an adhesive or fusion. As a result, the multistage hole 13 is provided. Reference numeral 2 denotes a low melting point soluble alloy grain accommodated in the hole 13 of the insulating plate 1 and is held in the small diameter portion 111 of the hole. 3 is a flux filled in the holes 13. Reference numerals 4 and 4 denote electrodes fixed by adhesive or fusion, covering the upper and lower sides of the holes 13 of the insulating plate 1, and are in contact with the low melting point soluble alloy particles 2.
[0008]
In the above temperature fuse, the low melting point soluble alloy grain 2 is melted by heating, and this molten alloy faces the large diameter hole 121 as shown in FIG. The electrode 4 wets and spreads and is divided between the electrodes 4 and 4. As the low-melting-point soluble alloy particles, usually a low-melting-point soluble alloy ball is appropriate, and one to a plurality of balls can be used. As long as a sufficient flux filling gap can be secured at a large diameter portion, use other than the ball is possible.
[0009]
3A is a plan view showing a temperature fuse according to claim 3, FIG. 3B is a cross-sectional view of FIG. 3A, and an annular insulating plate (ceramic plate). In the same manner as described above, a multi-stage hole 13 is provided in the same manner as above (in FIG. 3, (b), 11 is a central plate, 12 and 12 are upper and lower plates), The melting point soluble alloy grain 2 and the flux 3 are accommodated, and the metal foil electrodes 4 are fixed to both surfaces of the insulating plate 1.
In the above, the multistage hole 13 of the insulating plate 1 can also have a two-stage multistage hole structure having a small diameter and a large diameter, as shown in FIG. FIG. 4B shows the operating state of the temperature fuse under this multistage hole structure.
As the insulating plate 1, it is desirable to use a material that is easily repelled by molten alloy so that the electrodes are easily separated.
In the above, it is also possible to use a metal that is difficult to wet with the molten alloy, for example, Ni for one electrode, and a metal that easily wets the molten alloy, for example, Cu for the other electrode. In this case, the area of the electrode facing the hole is It is desirable to enlarge the metal side that is easily wetted by the molten alloy.
[0010]
FIG. 5 shows a mounting structure of the temperature fuse secondary battery according to the third aspect.
In FIG. 5, 51 is a negative electrode can. Reference numeral 52 denotes a metal safety valve (including a pressure relief plate with a cut in the middle of the plate thickness), and the central recess 521 is in electrical contact with the positive electrode collecting electrode 53. Reference numeral 54 denotes a metal positive electrode lid having a gas discharge hole 541 formed therein.
A is the temperature fuse shown in the above figure, and is sandwiched between the peripheral end of the safety valve 52 and the peripheral end of the positive electrode lid 53, and the peripheral end of the safety valve 52, the temperature fuse A, and the positive electrode lid 541. The upper end opening of the negative electrode can 51 is processed through the gasket 55 through the gasket 55 to electrically connect the electrodes 4 and 4 of the temperature fuse A to the safety valve 52 and the positive electrode lid 53.
In the above, the outline shape of the annular insulating plate 1 for the temperature fuse is made to be a quadrangle, a hexagon, an octagon, etc., in addition to a circle, according to the inner shape of the negative electrode can 51.
[0011]
The secondary battery to which the temperature fuse according to the present invention is attached is a secondary battery having a large capacity, such as a lithium ion battery or a nickel metal hydride battery, and a considerably large current flows during charging or discharging. When a device fails, overcurrent may flow and generate heat. Due to this heat generation, the low melting point soluble alloy grain 2 having the temperature fuse A is melted, and the molten alloy is subjected to the active force of the already melted flux as shown in FIG. The electrode 4 is wet and spreads to interrupt conduction.
In this case, by increasing the diameter of the large-diameter side of the multistage hole of the insulating plate, the molten alloy can be spread widely on the electrode surface, that is, it can be spread with a small thickness. Even if the depth is made shallower, and therefore the insulating plate is made thinner, the energization can be cut off. Accordingly, it is possible to reduce the temperature fuse, reduce the isolation dimension between the safety valve and the positive electrode cover, and minimize the increase in the storage space of the secondary battery.
Moreover, since the pressure release mechanism by the safety valve of the secondary battery and the positive electrode lid with the gas discharge hole can be maintained by making the insulating plate of the temperature fuse annular, the internal pressure of the secondary battery rises unexpectedly. However, the secondary battery can be prevented from exploding by releasing the gas from the gas discharge hole of the positive electrode lid by operating the safety valve.
[0012]
【The invention's effect】
In the temperature fuse according to the present invention, the secondary battery can be accommodated by attaching to the secondary battery by sandwiching it between the peripheral part of the safety valve and the peripheral part of the positive electrode lid. There is almost no increase in space. Therefore, the small size of the portable electronic device can be maintained well.
Further, in such mounting, since the temperature fuse is annular and the secondary battery pressure release mechanism is maintained, the safety valve can be reliably operated against an unexpected increase in internal pressure of the secondary battery.
[Brief description of the drawings]
FIG. 1 is a view showing an embodiment of a temperature fuse according to claim 1;
FIG. 2 is a view showing an operating state of the temperature fuse of FIG. 1;
FIG. 3 is a view showing an embodiment of a temperature fuse according to claim 3;
FIG. 4 is a view showing an embodiment of a temperature fuse according to claim 2;
5 is a view showing an embodiment of a temperature fuse mounting structure in a secondary battery according to claim 4. FIG.
FIG. 6 is a view showing a secondary battery.
[Explanation of symbols]
1 Insulating plate 13 Multistage hole 2 Low melting point soluble alloy grain 3 Flux 4 Electrode A Temperature fuse 52 Safety valve 54 Positive electrode lid 55 Gasket

Claims (4)

The insulating plate having holes penetrated therein contains the low melting point soluble alloy particles and the flux, the electrodes are fixed to both surfaces of the insulating plate, the electrodes are brought into contact with the low melting point soluble alloy particles, and the insulation A temperature fuse, wherein the holes of the plate are small and large multistage holes for sealing low melting point soluble alloy grains . The temperature fuse according to claim 1, wherein the insulating plate is annular. A hole different from the central hole is provided in the annular insulating plate, the low melting point soluble alloy particles and the flux are accommodated in the other hole, and the annular electrode is fixed to both surfaces of the annular insulating plate. A temperature fuse in a secondary battery, characterized in that a temperature fuse brought into contact with a melting point soluble alloy grain is sandwiched between a safety valve peripheral end and a positive electrode cover peripheral end of the secondary battery. Mounting structure. 4. A thermal fuse used in a temperature fuse mounting structure in a secondary battery according to claim 3, wherein a hole different from the central hole is formed in the annular insulating plate, and the low melting point soluble alloy is provided in the other hole. A temperature fuse characterized by containing grains and a flux, fixing annular electrodes on both sides of an annular insulating plate, and bringing each electrode into contact with a low melting point soluble alloy grain.

Images