JPH1140203A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance safety of a battery of providing a safety device, in which a temperature switch or a pressure switch and a varistor element are connected in parallel between each of battery terminals, to prevent over charge and to bypass only a battery with an abnormal temperature rise. SOLUTION: A temperature switch 22 has a contact 22 a on both ends of a bimetal and is curved upward and separated from a positive electrode terminal contact 6a and a negative terminal contact 7a under a normal temperature to turn into an off condition. When a temperature of the temperature switch 22 rises higher than a preset temperature, 80 deg.C for an example, its curve is reversed abruptly and the contact 22a of the temperature switch 22 makes a contact with the negative terminal contacts 6a, 7a to make an on position. That is, when the temperature of a power generating element rises to an abnormal temperature, a short circuited occurs between the positive electrode terminal 6 and the negative electrode 7. A varistor element 26 is to protect the overcharge of a battery by setting a varistor temperature to a level not less than a charging end voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary device used as a power source for products such as mobile devices such as electric vehicles and electric carts, portable devices such as video cameras and personal computers, backup devices in the event of a power failure, and security devices. The present invention relates to the safety of a battery used to prevent abnormal heat generation such as overcharging of a battery or internal short-circuit or ignition or explosion due to pressure increase, and to disconnect and bypass an abnormal battery.

[0002]

2. Description of the Related Art As a conventional battery safety protection device which is used by separating and bypassing a power generation element of a battery at an abnormal temperature, as disclosed in Japanese Patent Application Laid-Open No. 6-290767, a battery reaction portion is provided. Or in a chemical battery having a negative electrode terminal and a battery container also serving as another electrode terminal, a driving member driven by gas pressure or reaction heat generated at the time of abnormal reaction of the battery, connected to the electrode via an insulating material There is known a method of interrupting conduction between a partition plate sealing a battery container and an electrode terminal, and short-circuiting the electrode terminal and the battery container.

[0003] As for overcharge protection, Japanese Patent Application Laid-Open No. 5-234 has been disclosed.
As shown in Japanese Patent Publication No. 614, in a secondary battery in which a positive electrode, a negative electrode, and an electrolyte are sealed, a temperature switch or a temperature fuse is provided in series with the battery in a void portion in the container.
In a secondary battery in which a Zener diode is electrically connected in parallel and a positive electrode, a negative electrode and an electrolyte are sealed as shown in JP-A-5-325943,
In some cases, two series thermal fuses are connected in series to the positive terminal of the battery in a gap portion in the container, and a Zener diode is connected between the connection point of the two thermal fuses and the negative terminal of the battery.

[0004]

However, as disclosed in Japanese Patent Laid-Open No. 6-290767, a method of electrically disconnecting an electrode having an abnormal temperature from an external terminal and short-circuiting between a positive electrode terminal and a negative electrode terminal to bypass the electrode. Has the following problems. The method of simply shutting off the power generating element in the battery case at an abnormal temperature in an electric circuit is effective when there is an external cause such as an external short circuit, overcharging, or overdischarging. With respect to a short circuit caused inside the power generating element itself due to falling off, dendrite deposition, etc., there is no effect even if it is cut off from the external electric circuit. In addition, as for external factors, there is a variety of protection means since it is sufficient to shut off the battery and the external circuit, but for a short circuit in the battery, energy stored between the positive electrode and the negative electrode in the power generation element itself is discharged into the battery. Therefore, there is no means for protection at present.

When the temperature inside the battery case becomes abnormal as disclosed in Japanese Patent Application Laid-Open Nos. 5-234614 and 5-325943, the power generating element is electrically cut off by a temperature switch or a thermal fuse. However, it is clear that there is no protection function against an internal short circuit in the power generating element. Also, the Zener diode and the temperature switch, which are overcharge protection circuits, are installed in the battery container filled with the electrolytic solution, and need to be protected from corrosion by the electrolytic solution and corrosion by the electrochemical action during the operation of the battery. That is, the Zener diode and the temperature switch must be sealed with an electrolyte-resistant material.

However, components such as a Zener diode and a temperature switch can be sealed with an electrolyte-resistant resin or the like, but it is difficult to seal the connection between each electrical component and an electrode. In addition, the lead wires of electrical elements such as zener diodes and thermal fuses are generally made of copper-based metal, and the positive electrode current collector is made of aluminum foil due to the electrochemical reaction of the battery. There are problems that it is difficult to weld the wire and the aluminum foil, and that when a dissimilar metal is connected in the electrolytic solution, the wire rapidly breaks due to corrosion.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to prevent overcharging and increase an abnormal temperature among a plurality of secondary batteries connected in series. Short-circuiting the positive and negative terminals of the battery releases the stored energy out of the battery, and further bypasses only the abnormal battery.
An object of the present invention is to improve the safety of a battery and to provide a secondary battery that is easy to use.

[0008]

According to the present invention, in order to achieve the above object, a power generating element comprising an electrode group having a positive electrode, a negative electrode and a separator and an electrolyte is accommodated in a battery case.
Each electrode is connected with a lead terminal to each pole terminal penetrated through the sealing member, and a temperature switch or pressure is applied between each pole terminal of the battery at the outer part of the sealed container having the electrolyte sealed by the sealing member. A safety device in which a switch and a varistor element are connected in parallel is installed.

The safety device normally turns off the positive terminal and the negative terminal and turns on the positive and negative terminals when the temperature or the pressure rises. The stored energy of the power generating element is consumed outside the battery, and only the abnormal battery is used by bypass. Further, by setting the varistor voltage of the varistor element to be equal to or higher than the charge end voltage of the battery, overcharge protection of the battery can be performed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a secondary battery according to the present invention will be described below with reference to the drawings, taking a lithium ion secondary battery as an example. FIG. 1 is a structural vertical sectional view showing an embodiment of the secondary battery of the present invention, and FIG.
FIG. 3 is a cross-sectional view of FIG. In the figure, reference numeral 1 denotes a positive electrode, and a positive electrode current collector 1a made of aluminum foil
A positive electrode mixture 1b using an inorganic lithium intercalation material as a positive electrode active material (for example, LiM
_{n 2 O 4, LiCoO 2,} LiNiO 2 or the like, carbon as a conductive agent, a mixture adjusted polyvinylidene fluoride as a binder) is obtained by holding the. Reference numeral 2 denotes a negative electrode, and a negative electrode mixture 2b (for example, a mixture of graphite as an active material and polyvinylidene fluoride as a binder) on both surfaces of a negative electrode current collector 2a formed of a copper foil and having a lithium intercalation carbon material as a negative electrode active material. Adjusted). Reference numeral 3 denotes a separator made of a microporous polyethylene film or polypropylene film. When the temperature of the polyethylene film rises,
The shutdown start temperature at which the microporous closes due to the melting of the film itself is about 130 ° C, and the shutdown start temperature of the polypropylene film is about 150 ° C. The positive electrode 1 and the negative electrode 2 are spirally wound in a state where they face each other with the separator 3 interposed therebetween, thereby forming an electrode group 15. In this case, the separator 3 is wound slightly wider than the positive electrode 1 and the negative electrode 2, and is further wound several times alone at the core portion and the end portion of the winding, so that the separator 3 can be wound between the positive electrode and the negative electrode and around the electrode group. Has insulation properties.
The electrode group 15 is immersed in an electrolytic solution (not shown) to become a power generating element. The electrolyte is LiPF ₆ , LiBF ₄ ,
A solution in which a lithium salt such as LiClO ₄ or LiAsF ₆ is dissolved as an electrolyte in an organic solvent (single or a mixture of propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, etc.) is used.
10 is a battery case made of stainless steel, nickel-plated iron,
Nickel-plated copper or aluminum is used, and the power generating element composed of the electrode group 15 and the electrolytic solution is housed in a cylindrical container having a bottom. Is sealed by caulking in the opening of the first embodiment. That is, the electrode group 15 and the electrolyte are sealed by the sealing member 11, and each component of the safety device is completely isolated from the electrolyte.

The sealing member 11 is made of a metal material having good heat conductivity, such as stainless steel, nickel-plated iron, nickel-plated copper, and aluminum. In addition, an insulating plate 12 is provided on the side of the sealing member 11 in the battery case 10 and the container bottom 10a in order to maintain electrical insulation between the battery charging section and the battery case 10.
a and 12b are installed. Reference numeral 4 denotes an aluminum material positive electrode lead, which is connected to the positive electrode current collector 1a of the positive electrode 1 and the aluminum material positive electrode terminal 6 by welding or the like. Reference numeral 5 denotes a nickel or copper negative electrode lead, which is connected to the negative electrode current collector 2a of the negative electrode 2 and a nickel or copper negative electrode terminal 7 by welding or the like. Numeral 13 denotes an insulating destant which secures a space between the electrode group 15 and the sealing member 11 for accommodating and storing the positive electrode lead 4 and the negative electrode lead 5 together.
The electrode group 15 is pressed so as not to move in the battery case 10.

The positive terminal 6 and the negative terminal 7 are connected to the sealing member 11.
A hermetic seal 8 which is electrically insulated with a glass or plastic layer interposed and has a sealing property.
, And the portion that penetrates through the switch case 21 and goes out of the switch case becomes an electrical connection with the outside. The explosion-proof hole 11a provided in the sealing member 11 is sealed with an explosion-proof valve 9 (FIG. 3) made of a metal plate or a thin-film metal plate having a weak point such as a cut, so that the pressure inside the battery case 10 rises abnormally. This causes the battery case 10 to break when it becomes high pressure, thereby preventing the battery case 10 from exploding. A gas vent hole 21b is also formed in the flange portion 21a of the switch case 21 located at the explosion-proof valve 9 so that gas can be directly discharged to the outside atmosphere.

The location of the explosion-proof valve is not limited to the sealing member, but may be any location as long as the blast gas is discharged to the outside of the enclosed switch housing of the switch case 21. The operating pressure of the explosion-proof valve 9 is determined based on the pressure rise limit in the battery case during actual use and the strength at which the battery case itself and the crimped portion do not break first, and is 10 kg / cm ² to 2 kg.
0 kg / cm ² is desirable. The safety device 20 is swaged so as to wrap the periphery of the cap member 11 in the form of a hat-shaped terminal case 21 made of an insulating material such as plastic and the periphery of the flange portion 21a to form an integral sealed space. A temperature switch 22 made of a thermally responsive bimetal, a shape memory alloy, a heat fusible metal, or the like is built therein.

The positive terminal 6 and the negative terminal 7 are bent in a crank shape on the surface of the sealing member 11 in the switch case 21, and have a positive terminal contact 6a and a negative terminal contact 7a in a horizontal portion thereof. Between the positive terminal contact 6a and the negative terminal contact 7a, a temperature switch 22 is screwed into the bottom of the switch case 21 by a support rod 23 via a spring 24, and then fixed by a nut 25. By adjusting the screwing amount of the support rod 23, the temperature switch 2
2 can be adjusted, and the contact pressure of the bimetal contact can be made appropriate.

The temperature switch 22 is a double-contact bimetal having contacts 22a at both ends of the bimetal. At a normal temperature, the temperature switch 22 is bent upward and separated from the positive terminal contact 6a and the negative terminal contact 7a to be in an off state. When it rises, the temperature switch contact 22a comes into contact with the positive terminal contact 6a and the negative terminal contact 7a and turns on. In other words, when the temperature of the power generating element becomes abnormal due to a rise in temperature, the positive electrode terminal and the negative electrode terminal are short-circuited by the temperature switch.

The spring 24 presses the temperature switch 22 against the end of the support rod 23 and absorbs the vibration of the bimetal plate when the temperature switch 22 performs the reversing operation to prevent chattering of the contacts. Reference numeral 26 denotes a varistor element. In the switch case 21, one terminal of the varistor element 26 is connected to the positive terminal 6 and the other terminal is connected to the negative terminal 7 by welding or the like. The varistor element 26 is a ceramic semiconductor containing zinc oxide as a main component and mixed and fired with several kinds of additives. When a positive or negative voltage is applied between both electrodes of the element, the voltage is gradually increased to reach the varistor voltage. It has the function of flowing a current maintaining this voltage.

FIG. 4 is a sectional view showing another embodiment of the safety device 20. As shown in FIG. In this figure, a pressure switch whose driving source is pressure is used instead of the temperature switch, and the other structure is the same as that of the embodiment shown in FIGS. Reference numeral 27 denotes a pressure movable body that expands and contracts due to pressure of a bellows, a diaphragm, or the like, and is attached to the switch case 21 by soldering, welding, or the like so as to close the opening hole 11b of the sealing member 11. Reference numeral 28 denotes a switch piece and a contact 28 at each end.
a, and each contact 6a, 7a of the positive terminal 6 and the negative terminal 7
Facing. The switch piece 28 is movably disposed between the pressure movable body 27 and the bottom of the switch case 21 sandwiched between an insulating push rod 29 and a braking spring 30.

The contact 28a of the switch piece 28 is located at a position far from the positive terminal contact 6a and the negative terminal contact 7a because the force of the braking spring 30 is greater than the expansion force of the pressure movable body 27 at normal low pressure. When the pressure rises above the pressure, the expansion force of the pressure movable body 27 overcomes the force of the braking spring 30, and the switch piece 2
8, the contact 28a is pressed against the positive terminal contact 6a and the negative terminal contact 7a, and short-circuits between the two terminals. That is, in the above-described embodiment, the positive electrode terminal and the negative electrode terminal were short-circuited due to the direct temperature rise. However, in this embodiment, the pressure inside the battery increased secondary to the temperature rise or the pressure rise due to the generation of decomposition gas of the electrolyte. In addition, a short circuit occurs between the positive terminal and the negative terminal.

FIG. 5 is an electric circuit block diagram when a plurality of secondary batteries of the present invention are connected in series and used. The figure shows an assembled battery 41 in which n cells (40a to 40n) are connected in series, and the output terminal XY of the assembled battery 41 is a fuse 4
2, control circuit 44 and load 4 via main switch 43
5 is connected. Reference numeral 46 denotes a current sensor for detecting a current flowing through the battery pack 41, and reference numeral 47 denotes a temperature sensor for detecting a temperature of the battery pack, which is input to the control circuit 44, respectively. Reference numeral 48 denotes an output signal output from the control circuit 44 when the current sensor 46 or the temperature sensor 47 detects an abnormal current or abnormal temperature, and serves to turn off the main switch 43. Assuming that the voltage of the unit cell is E (V) in this circuit, the voltage between the output terminals X and Y of the assembled battery is n × E (V). a is a positive electrode terminal 6 connected to the positive electrode of the power generating element, b
Denotes a negative electrode terminal 7 connected to the negative electrode of the power generating element. Normally, the terminal ab is in the off state, and switches to the on state when the battery becomes abnormal due to a rise in temperature or pressure. VT represents a varistor element 26 connected between the positive and negative terminals of each cell.

Next, a method of assembling a secondary battery according to the present invention will be described. First, the positive electrode lead 4 and the negative electrode lead 5 are attached to the positive electrode 1 and the negative electrode 2, respectively, by spot welding or ultrasonic welding. At this time, the number of leads to be attached is increased or decreased depending on the size of the battery capacity. The positive electrode 1 and the negative electrode 2 are wound with the separator 3 interposed therebetween, and the end of the winding is stopped with a tape or the like to form an electrode group 15. From the bottom 10a side of the bottomed cylindrical container, an insulating plate 12b, an electrode group 15,
The positive electrode lead 4 and the negative electrode lead 5 are bundled and put together in the order of the insulating detent 13. On the other hand, safety device 2
Numeral 0 incorporates a varistor element 26 and a temperature switch mechanism or a pressure switch mechanism in a switch case 21 and is covered with a sealing member 11 to form a hermetically sealed structure.

Next, the insulating plate 12a is overlaid on the sealing member 11 side of the safety device 20, and the positive electrode lead 4, the negative electrode lead 5
Is welded to the positive terminal 6 and the negative terminal 7 of the sealing member 11.
Next, necking is formed near the opening of the battery case 10, and then an electrolytic solution is injected, and the safety device 20 is sealed by caulking via a gasket 19 to complete the safety device 20. As described above, the secondary battery provided with the safety device 20 can be assembled without changing the conventional assembly process, so that the workability is good.

Next, the operation of the secondary battery according to the present invention will be described. When a battery is overcharged to a voltage equal to or higher than a charge termination voltage due to a failure in a charging circuit, a chemical reaction other than the battery reaction as lithium intercalation is performed to decompose an electrolytic solution, thereby deteriorating the battery and increasing the pressure of the battery. Further, when overcharging proceeds or is rapidly charged, lithium metal precipitates on the negative electrode due to a dentite reaction, breaks through the separator 3, causes a short circuit between the positive electrode and the negative electrode, and causes a short-circuit current to flow to an abnormal temperature. Also, use at high temperature beyond the normal battery operating temperature range, external short circuit due to misuse, internal short circuit inside the battery for some reason,
The battery generates heat and reaches an abnormal temperature. When the temperature of the secondary battery rises, the film of the separator 3 between the positive electrode 1 and the negative electrode 2 melts at 130 ° C. to 150 ° C., and the micropores of the film close to shut down the movement of lithium ions between the positive and negative electrodes. There is a function to cut off the current by the effect.

However, a polyethylene film or a polypropylene film, which is a material of the separator, may melt and shrink due to a further rise in temperature, and may not be able to secure insulation between the positive and negative electrodes, resulting in a short circuit between the electrodes. When the temperature inside the battery exceeds 150 ° C., the positive electrode active material used for the electrode causes a thermal runaway, which is a dangerous temperature range where smoke, ignition, and explosion occur. In other words, LiM which is a positive electrode active material
A thermal runaway state occurs with rapid heat generation due to an oxygen elimination reaction from a crystal lattice of n ₂ O ₄ , LiCoO ₂ , LiNiO ₂ or the like.
The oxygen desorption starting temperature varies depending on the type of active material, the composition ratio of each element, and the state of charge, but is in the range of 150 ° C to 400 ° C.

Here, the battery abnormally rises in temperature for some reason, the electrolytic solution in the battery decomposes and gas is generated, and the electrolytic solution and the active material of the positive electrode and the negative electrode generate a gas to generate gas. Consider the case where the pressure inside rises. The abnormal temperature rise of the battery raises the temperature of the temperature switch 22 of the safety device 20 through the sealing member 11 having good heat conduction, inverts the bimetal, and the positive electrode terminal 6 and the negative electrode terminal 7 are short-circuited while the power generating element is connected. Alternatively, when the electrolyte gasifies due to the abnormal temperature of the battery and the pressure in the battery case 10 increases, the pressure movable body 27 expands and the switch piece 2
8, the positive electrode terminal 6 and the negative electrode terminal 7 are short-circuited while the power generating element is connected. That is, a of the abnormal unit cell in FIG.
-B is short-circuited.

Accordingly, the electrodes of the abnormal unit cell are short-circuited, and the abnormal unit cell is cut off to form a bypassed series circuit, and the output voltage is continued at (n-1) × E (V). I do. At this time, when the temperature of the battery rises due to an internal short circuit, the stored energy of the sealed power generation element is discharged between the positive electrode and the negative electrode inside the battery and simultaneously discharged outside the battery case 10 through the temperature switch or the pressure switch. This has the effect of suppressing the temperature rise in the battery.

That is, in the case of an internal short circuit, the stored energy completes the supply and consumption in the battery. However, according to the present invention, a part of the stored energy is consumed outside the battery, so The temperature rise is reduced, and it is possible to reduce the danger of a dangerous explosive temperature condition. It is safe to explode when discharging the charging energy,
It has also been confirmed in the results of burner combustion tests on batteries with different amounts of charge. In other words, when the battery was heated, the battery with a small charge did not explode at all, but when the charge was increased, an explosion occurred, and the explosive power increased as the charge increased and the explosion temperature decreased. became. When the temperature of the battery rises due to an external short circuit, the output signal 48 is sensed by the current sensor 46 and the temperature sensor 47 of the control circuit.
Is issued, the main switch 43 is turned off, and the battery pack 41 is turned off.
And the load 45 is protected.

Further, when the control circuit 44 fails and an overcurrent flows, the fuse 42 is blown and double protected.
In addition, the pressure inside the battery rises to 10 kg / cm ^{2 to} 20 kg /
When the pressure reaches cm ² , the explosion-proof valve 9 ruptures and discharges gas out of the battery case to reduce the explosive power of the battery. At this time, the high-temperature gas is released from the gas vent hole 21b outside the closed space having the temperature switch or the pressure switch, so that the switch does not corrode or the high-temperature gas of the electrolyte does not ignite. The operation temperature of the temperature switch 22 is set to 80 ° C.
130 ° C., and the return temperature is preferably −20 ° C. or less.

By doing so, once the device is operated, it will not recover unless it is forcibly cooled in a practical temperature range, and safety will be improved. In addition, the temperature switch 22 when an external short circuit occurs
Need to be set higher than the operation temperature of the control circuit 44. That is, when the temperature switch 22 is operated earlier than the control circuit 44 due to the abnormal temperature rise due to the external short circuit, the load is protected because power is not supplied to the load because the positive and negative terminals are short-circuited. However, this is because the external short-circuit state is continued until the battery itself discharges the stored energy, and the temperature rise of the battery itself is continued as it is.

On the other hand, the operation value of the pressure switch is set lower than the operation value of the explosion-proof valve. When the internal pressure of the battery is 3 kg / cm ² or more, the pressure switch is operated first to reduce the stored energy in the battery, 10 kg / cm ^{2 to} 20 kg / cm ² after exerting the effect of reducing the temperature rise and pressure rise
It is desirable to safely guide the explosion-proof valve rupture in ² .

Next, let us consider a case where charging does not stop even if the charging circuit breaks down and the voltage between the electrodes of the unit cell becomes, for example, 4.2 V, which is the charging end voltage. If the varistor voltage of the varistor element 26 is set to 4.3 V which is higher than the charging end voltage and slightly higher than this, when the cell voltage is overcharged to 4.3 V, the varistor element will have a varistor voltage of 4.3 V.
Current is supplied while the voltage is maintained, and the charging of the cell to 4.3 V or more can be prevented. In general, in the case of a lithium ion secondary battery, if the battery is overcharged at a charge end voltage or higher, an abnormal temperature rise of the battery or a pressure rise due to gas generation occurs.

[0031]

As described above, according to the present invention, a power generating element comprising a positive electrode, a negative electrode and an electrolyte is housed in a battery case, and a heat-responsive temperature switch capable of short-circuiting between electrode terminals or a pressure-driven pressure switch. The opening of the battery case is sealed by a safety device in which a switch and a varistor element are connected in parallel between the positive and negative terminals, and the safety device is usually in an open state between the positive and negative terminals, when the temperature of the battery rises and At the time of pressure rise, the connection between the positive and negative terminals was made conductive through a temperature switch and a pressure switch. Therefore, in the case of an assembled battery in which a plurality of cells are used in series, when a certain cell rises in abnormal temperature, the positive and negative terminals of the abnormal battery are short-circuited and bypassed, and the remaining normal cells can be continuously used. So easy to use.

In addition, even when an abnormal temperature rise occurs due to an internal short circuit, the stored energy of the power generating element is short-circuited through the switch of the safety device, and the energy is released to the outside of the battery case. improves.
In addition, since the sealing member serving as the heat receiving plate of the safety device is a single metal plate having good heat conductivity, it has good thermal response to a change in heat inside the battery, and the sealing reliability of the battery case sealing portion is high.

Further, since the contact switching circuit by the switch in the safety device is closed by the switch case 21 and the sealing member 11 and the explosion-proof valve is outside the closed space where the bimetal switch is provided, dust and gas are removed. There is no danger of contact, there is little contact failure of the contacts, and there is no danger of igniting the high-temperature gas of the flammable electrolyte ejected by the arc of the contacts. Further, it is possible to provide a secondary battery capable of preventing overcharge of a single battery by the voltage-current characteristics of a varistor element incorporated in the safety device.

[Brief description of the drawings]

FIG. 1 is a structural sectional view showing one embodiment of a secondary battery of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 2;

FIG. 4 is a structural sectional view showing another embodiment of the safety device for a secondary battery of the present invention.

FIG. 5 is an electric circuit block diagram using the secondary batteries of the present invention connected in series.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Positive electrode, 1a ... Positive electrode collector, 1b ... Positive electrode mixture, 2 ... Negative electrode, 2a ... Negative electrode collector, 2b ... Negative electrode mixture, 3 ... Separator, 4 ... Positive electrode lead, 5 ... Negative electrode lead, 6 ... Positive terminal,
6a: contact of positive terminal, 7: negative terminal, 7a: contact of negative terminal, 8: hermetic seal, 9: explosion-proof valve, 10 ...
Battery case, 10a: bottom of container, 11: sealing member, 11
a: Explosion-proof hole, 11b: Opening hole, 12a, 12b: Insulating plate, 13: Insulated distant, 15: Electrode group, 19: Gasket, 20: Safety device, 21: Switch case, 21
a: flange, 21b: vent hole, 22: temperature switch,
22a: temperature switch contact, 23: support rod, 24: spring, 25: nut, 26: varistor element, 27: pressure movable body, 28: switch piece, 28a: switch piece contact, 29: push rod, 30: braking Spring, 40a, 40b, 4
0n: single cell, 41: assembled battery, 42: fuse, 43 ...
Main switch, 44: control circuit, 45: load, 46:
Current sensor, 47: temperature sensor, 48: output signal.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Michiko Sakairi 800, Tomita, Ohira-cho, Shimotsuga-gun, Tochigi Pref.Hitachi, Ltd.

Claims (1)

[Claims] 1. A switch for short-circuiting between a positive electrode terminal and a negative electrode terminal of a battery when the temperature of the battery is 80 ° C. or more or the internal pressure of the battery is 3 kg / cm ² or more, and the internal pressure of the battery is 10 kg / cm ² or more.
An explosion-proof valve that opens at 20 kg / cm ² is provided outside the switch case.