JP3111276B2 - Secondary battery explosion prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents an internal short-circuit in a secondary battery or a burst or an ignition due to an abnormal temperature rise in the battery due to overcharging or the like, and also prevents overload and external short-circuit. The present invention relates to a highly safe secondary battery explosion prevention device capable of protecting a battery from overcurrent.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller and more widely used, demand for secondary batteries such as lithium-ion batteries has been steadily increasing. It is well known that in addition to the demands on performance, high reliability is required from the viewpoint of safety, and further improvements are being made to meet such demands. is there. It is no exaggeration to say that depending on the results, the fate of the future of the rechargeable battery is hindered. In particular, at present, in particular, the emission of CO ₂ has been greatly highlighted as a global environmental pollution problem. It is important to provide a secondary battery with extremely high safety in use and to promote the use thereof, because it also helps to solve environmental pollution.

[0003] Conventional safety measures will be described by taking a particularly dangerous lithium ion secondary battery as an example among secondary batteries. A lithium ion secondary battery is safer than a secondary battery using metallic lithium. Although it is said to be highly susceptible, it has a flammable organic electrolyte inside and is a high energy density battery, so overcharging, overdischarging, external shorting, internal shorting,
It is known that when severe conditions such as excessive current and abnormally high temperature are encountered, there is a possibility of rupture or ignition. Conventionally, in order to prevent such an abnormality from progressing, a shutdown separator, PTC (positive t
Safety measures such as an element (protective element), a protection circuit and a current cutoff mechanism, and a safety valve are taken.

[0004] Among the various abnormal conditions described above, the problem of explosion or ignition due to overcharging or internal short circuit during charging is an abnormal phenomenon inside the battery, and the positive electrode, the negative electrode, the separator, etc. in the battery. When an abnormal chemical reaction occurs and an excessive chemical reaction starts, and it repeats in a short time, the internal temperature rises, and the chemical reaction increases, and the internal current value also increases, and as a result, Internal temperature is 100
When the temperature exceeds ℃, it is no longer possible to stop the chemical reaction, resulting in an explosion and an accident such as the ejection of an electrolyte.

[0005]

Conventionally, however, the conduction between the battery and the external circuit is interrupted only by a current fuse and a thermal fuse in the event of an abnormality, which does not provide any protection against internal chemical reaction enhancement. Therefore, the emergence of a safety device that can provide an effective protection function against an explosion, which is not a necessary and thorough security measure, is strongly involved in the art.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made in order to solve the above-mentioned problems. It is an object of the present invention to provide a temperature control device in which a temperature rise phenomenon inside a secondary battery causes an explosion. It is an object of the present invention to provide a secondary battery explosion prevention device which ensures the safety of a battery with high reliability by stopping the chemical reaction, which is the cause of the reaction, quickly and surely until the battery reaches the threshold.

[0007]

The present invention has the following configuration to achieve the above object. That is, the invention of claim 1 of the present invention relates to the inside of the secondary battery.
Conductive resistance wire with low resistance of about 1/10 compared to resistance
The current is converted into Joule heat by being spirally wound around the core
Back electromotive force to suppress inrush current.
Electric-to-heat converter (electric curre)
nt-radiation device)
Is a discharging means, the secondary battery and the temperature detecting means for detecting the temperature inside, the positive and negative electrodes a power supply and an external circuit before Symbol temperature detection means conducts operation in response to outputs a normal temperature signal rechargeable battery Each of the operation switching means for forming a closed loop circuit between the power supply between the positive and negative electrodes of the secondary battery and the discharging means in response to outputting the abnormal temperature signal, and forming a closed loop circuit with the discharging means , The core layer of the insulator and the core layer from both sides
It has three layers, a top thin layer and a bottom thin layer of the conductor to be sandwiched,
A hole as a vent hole is provided in the central part,
Body formed into a thin disk that can be housed in the battery case
The main body is stored in
Connect the back side thin layer to the positive terminal and the
A secondary battery explosion prevention device, which is interposed between a top cover of a secondary battery and a safety valve . here,
The closed-loop circuit means a circuit that forms a closed current path.For example, a closed-loop circuit including a power supply between the positive and negative electrodes of a secondary battery and a discharging unit includes a power supply between the positive and negative electrodes and a discharging unit connected in parallel. Circuit.

[0008] The invention of claim 2 of the present invention provides:
The invention according to the first aspect is characterized in that a current fuse that cuts off by the flow of overcurrent and disconnects conduction between the positive electrode and the positive electrode side terminal of the secondary battery is attached to the element member.

Further, the invention of claim 3 of the present invention provides:
The invention according to claim 1 or 2, wherein the temperature detecting means comprises a temperature sensor such as a thermistor, and the operation switching means comprises a semiconductor contactless relay having a flip-flop circuit as a logic element.

[0010]

[0011]

Further, the invention of claim 4 in the present invention is as follows:
The invention according to claim 3 is characterized in that the temperature detecting means is provided along the peripheral wall of the hole.

[0013] The invention of claim 5 in the present invention provides:
According to the invention of the fourth aspect, the discharge means is connected to the negative electrode of the secondary battery by a conductor that extends through the hole and the gas vent hole in the battery and extends to the bottom of the battery. And

The present invention having such a configuration operates as follows. That is, referring to the conceptual diagram of FIG. 1 showing the basic configuration of the present invention, for example, when a chemical reaction in the secondary battery 19 starts due to overcharging during charging and the internal temperature rises rapidly, the thermistor The temperature detecting means 2 realized by such a temperature sensor detects this temperature and outputs an abnormal temperature signal when the temperature reaches a predetermined dangerous temperature (generally 100 to 120 ° C.). In response to this output, the operation switching means 3, which is realized by a semiconductor contactless relay, conducts, and the power supply E between the positive and negative electrodes of the secondary battery 19, which has formed a circuit because it has been in a normal state until now, is provided. And a closed loop circuit between the external circuit 6 such as a charging device, and a closed loop circuit between the discharging means 4 and the power supply E between the positive and negative electrodes of the secondary battery 19 realized by the electro-thermal converter device. .

Thus, the power supply E between the positive and negative electrodes of the secondary battery 19
Discharges all the electric energy held by the discharge means 4
Since it is converted into Joule heat and released, the voltage value inside the secondary battery 19 becomes 0 Volt almost instantaneously, and the chemical reaction that has started to increase rapidly stops with the disappearance of the electric energy which is the main cause. As a result, high-risk abnormal situations such as explosions are eliminated here.

On the other hand, there are a wide variety of factors that can be considered as accidents due to internal short circuits.
What appears as a result is the same phenomenon as in the case of overcharging described above. That is, an abnormal chemical reaction, an increase in temperature, and an increase in current value caused by the abnormal chemical reaction. In this case as well, the abnormal (dangerous) temperature of the temperature detecting means 2
The conducting operation of the operation switching means 3 is performed, and the electric energy is discharged to the discharging means 4, so that the current disappears to zero value and the chemical reaction is suppressed at the same time.

The temperature detecting means 2 includes various temperature sensors utilizing a change in pressure, a change in electric resistance (temperature measuring resistance element including a thermocouple and a thermistor), a thermoelectromotive force, and the like. It is possible to select an appropriate one from among detecting means capable of converting a change in temperature into an electric signal and outputting the electric signal.

In addition to the above-described abnormal phenomena on the inside of the battery, in addition to the rupture and ignition caused by an external short circuit or the like outside the battery, the present invention according to claim 2 employs the provision of the current fuse 5 in the element member. The current flowing in due to an external short circuit or the like is cut off by the blowing of the current fuse 5, and therefore does not affect the built-in secondary battery 19 at all. In addition, by selecting and using the current fuse 5 whose fusing current-fusing time characteristic satisfies a condition that can be adapted by comparison with the current capacity of the secondary battery 19, the secondary battery 19 is protected from external It is safeguarded against surging and the like, and the protection measures in a range that was insufficient with the conventional PTC element are thorough.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 2 is a partially cutaway structural view of the secondary battery explosion prevention device 1 according to the embodiment of the present invention.
(A) is a front view, (B) is a plan view. FIG. 3 is an exploded perspective view showing a state in which the first embodiment is incorporated in a secondary battery.

The secondary battery explosion prevention device 1 according to the above-described embodiment basically includes a main body 7, a temperature detecting means 2, an operation switching means 3, and a discharge device as each element stored in the main body 7. Means 4. Note that the implementation form of this further but current fuse 5 is attached as a single element members, such as the external circuit provided overcurrent protection means associated with the current fuse 5 is the secondary battery, the external circuit It may be omitted as necessary depending on the mode.

The main body 7 has the shape of a thin disk, and if the secondary battery 19 to be incorporated is a commonly used AA battery with an outer diameter of about 18.5 mm, the diameter is about It is formed into a disk of 17.0 mm and a thickness of about 2.0 mm. The main body 7 is formed into a laminated body having three layers of a core layer 8 made of an electric insulator such as ceramics, a front thin layer 9 made of a thin conductive sheet sandwiching the core layer 8 from both front and back surfaces, and a back thin layer 10. It is formed. The front thin layer 9 and the back thin layer 10 are usually made of an ultra-thin plate made of nickel-plated copper, and are made of insulating paperboard to maintain electrical insulation with respect to each of the element members in the core layer 8. An insulating film 12 made of an insulating film or the like is coated on the inner surface. Further, a hole 11 used as a gas vent hole is provided in the main body 7 so as to pass through the central portion.

When the main body 7 is assembled at a predetermined position in the secondary battery 19, the front thin layer 9 and the rear thin layer 10 are located on the outer side and the latter on the inner side, respectively. to the positive terminal T _H of the skin layer 9 is the secondary battery 19, in which the back surface thin layer 10 are respectively electrically connected to the positive electrode side electrode inside (see FIG. 1).

The temperature detecting means 2 is a member provided for measuring the internal temperature of the secondary battery 19. Referring to FIG. 1, a voltage divider type resistance circuit having a temperature sensor such as a thermistor as an element. Is used. As the thermistor, either a positive characteristic thermistor or a negative characteristic thermistor can be used. For example, a positive characteristic thermistor is disposed in the core layer 8 along the peripheral wall of the hole 11 as shown in FIG. Is done. That is, as the internal structure of the lithium ion secondary battery,
A gas hole must be provided to release the gas generated when a chemical reaction involving heat generation occurs.The gas hole reaches the bottom of the battery and the center of the battery is hollow. Arranging the body of the thermistor along the peripheral wall with respect to the hole 11 formed to communicate with the gas hole is just as capable of quickly and accurately detecting the temperature inside the battery. It's just the right place.

The temperature detecting means 2 comprising a temperature sensor such as a thermistor detects a temperature within a normal temperature range of a preset temperature, which usually reaches an abnormal temperature point of 100 to 120 ° C. in the case of a secondary battery. And outputs an abnormal temperature signal by detecting a temperature equal to or higher than the abnormal temperature point. The normal / abnormal temperature signal is transmitted to the operation switching means 3 by a control signal. Is to be transmitted as.

[0026] The actuating switching means 3, the secondary battery of the type and form of the object, reed structure, is suitably selected from among various relay contactless structure, the two according to the implementation form of this order In the case of the battery explosion prevention device 1, a semiconductor contactless relay is used in consideration of its suitability in terms of compactness and robustness. For example, a configuration in which a power transistor is used as an element and a flip-flop circuit is used as a logic element It is provided in the core layer 8 using the transistor circuit described above. As described above, an abnormal temperature signal or a normal temperature signal is input to the operation switching means 3 realized by the semiconductor non-contact relay from the temperature detecting means 2 composed of a positive temperature coefficient thermistor. The output part of the semiconductor non-contact relay simulated by the switching contact on the top 1 operates so that the normally closed circuit side is opened and the normally open circuit side is closed by inputting the abnormal temperature signal as a set signal, and the normal temperature signal is output. Is input as a reset signal, a reverse operation is performed so that the normally open circuit side is opened and the normally closed circuit side is closed, so-called switching operation is performed.

Next, the discharging means 4 includes a core 14 formed of a flat rectangular chip by an insulator such as ceramics.
A conductive resistance wire 13 as a resistor made of copper, nickel, stainless steel, or the like is spirally wound, and an outer cylinder 16 made of an insulator such as ceramic is surrounded therearound. A current-to-heat converter having a configuration in which an arc extinguishing agent 17 such as silicic acid / silica sand powder is filled therein is used.

The conductive resistance wire 13 has a sufficiently low resistance (for example, about 1/10 ) of the internal resistance (for example, 100 to 120 mΩ in the case of an AA battery) of the secondary battery 19 to be incorporated. The resistor has a resistance of 10 to 12 mΩ in the case of an AA battery, and has both ends fixed to connection terminal plates 15 provided on the end face of the core 13.

The conductive resistance wire 13 spirally wound as described above functions as an element for converting the inflowing current into heat by the Joule heating effect, and at the same time, reduces the inrush current generated instantaneously. On the other hand, it has the function of generating a back electromotive force for preventing this to some extent,
It is possible to suppress the increase in the inflow current and to convert it to heat and release it while performing an effective discharge action, and to promote arc extinguishing action and heat radiation of Joule heat in case of emergency. The operation is performed by the arc extinguishing agent 17.

The operation switching means 3 comprising a semiconductor non-contact relay and the discharging means 4 comprising a current-to-heat converter are:
By making full use of microfabrication technology such as etching and laser light irradiation, it is possible to manufacture low-cost, ultra-small and mass-produced products, and miniaturized enough to be built into AA batteries. The secondary battery explosion prevention device 1 can be provided.

On the other hand, the current fuse 5 is a general-purpose product that has a condition that the fusing current-fusing time characteristic can be adapted in comparison with the current capacity of the target secondary battery 19 and that can be downsized. It is selected from among and arranged in the heart layer 8,
For example, an AA battery having a fusing current of 15 A is provided.

[0032] In the secondary battery暴爆prevention device 1 according to the implementation embodiments Do that in this configuration, actuating the switching means 3 comprising a semiconductor contactless relay, as simulated by the switching contact, the common side terminal corresponding portion It is connected to the back thin layer 10, the part corresponding to the normally closed terminal is connected to one terminal of the current fuse 5, and the part corresponding to the normally open terminal is connected to the current-heat converter 4.
To one of the connection terminal boards 15. The current-to-heat converter 4 connects the other connecting terminal plate 15 to the negative terminal _TL of the secondary battery 19 via a conductor 18 as described later, for example, the bottom of a battery case 20 (see FIG. 3). Connect to The current fuse 5 has the other terminal connected to the surface thin layer 9.
Connect to Such a connection process to be performed between the respective element members can be easily performed in parallel with assembling the respective element members in the core layer 8.

As described above, each of the element members 2, 3,
As shown in FIG. 3, the secondary battery explosion preventive device 1 formed in a thin disk body in which the battery 4 and 5 are incorporated in the main body 7 has a thin surface layer 9 on the upper side, that is, on the outer side of the battery. (External circuit side) so that the top cover 2 of the secondary battery 19
3 and is stored in the battery case 20 between the safety valve 22. In this case, the thin surface layer 9 is
Of the positive terminal T _H, respectively electrically connected to the positive electrode side electrode backside thinned layer 10 is not internal illustrated, also current -
A conductor 18 formed in, for example, a thin plate piece connected to the other connection terminal plate 15 of the heat conversion device 4 hangs down through the center of the hole 11, and the center of the safety valve 22 and the battery case The battery case 20 passes through a gas vent hole provided at the center of the battery case 20 and reaches the inner bottom portion of the battery case 20. Here, the battery case 20 is electrically connected to the battery case 20 as a negative electrode side terminal _TL by crimping. You. In FIG. 3, reference numeral 21 denotes a gasket in which the safety valve 22 is stored.

The secondary battery 19 in which the secondary battery explosion prevention device 1 is housed as described above is connected to the external circuit 6 and is used as a DC power supply. Since the temperature is in the temperature range and the operation switching means 3 is in the normal operation state, the closed loop circuit formed between the power supply E between the positive and negative electrodes of the secondary battery 19 and the external circuit 6 such as a charging device is held. Normal charging or discharging.

In this state, when an abnormal chemical reaction starts in the secondary battery 19 due to overcharging during charging, an internal short circuit, or the like, and the internal temperature rises rapidly and reaches the above-mentioned abnormal temperature, the temperature is raised. The detection means 2 detects and outputs an abnormal temperature signal, and in response to this output, the operation switching means 3 switches to the abnormal side and operates. As a result, a closed loop circuit between the positive / negative power supply E and the external circuit 6 is cut off, and a closed loop circuit is formed between the positive / negative power supply E and the discharging means 4.

As a result, the stored energy held by the power supply E between the positive electrode and the negative electrode flows through the conductive resistance line 13 and is discharged instantaneously in its entirety, converted into Joule heat and released. Instantaneously drops to 0 Volt, thus the increasing chemical reaction stops rapidly due to the disappearance of the stored energy. Therefore, an extremely dangerous abnormal situation such as a bomb explosion is prevented here and safety is established.

On the other hand, when an overcurrent exceeding the rated current flows to the secondary battery 19 due to an external short circuit outside the battery, the current fuse 5 is blown to disconnect the power supply between the positive / negative power source E and the external circuit 6. To shut off the closed loop circuit formed in Therefore, the overcurrent flowing through the battery disappears, and the secondary battery 19 can be protected from the overcurrent.

[0038] In the secondary battery暴爆prevention device 1 according to the implementation embodiments of the present invention described above, and the resistor circuit of the voltage divider type for the temperature detection means 2 composed of a temperature sensor such as a thermistor as elements, flip Needless to say, it is necessary to supply power to the operation switching means 3 comprising a semiconductor contactless relay having a logic circuit as a logic element in order to operate them. Although not shown in FIGS. 1 and 2, a DC voltage from a power supply E between the positive and negative electrodes, which is the only power supply existing in the secondary battery 19, is applied to the resistance circuit and the operation switching means 3. It has such a circuit configuration.

[0039]

[0040]

[0041]

[0042]

The present invention is embodied in the form described above and has the following effects. That is,
Since the temperature detecting means provided inside the battery detects the rise in the internal temperature of the battery and switches and operates the operation switching means, the secondary battery is discharged to the discharging means 4 as soon as possible before firing or rupture. The root cause of the temperature rise is quickly eliminated and the battery can be reliably protected from explosion.

Further, in this case, further heat generation of the battery is suppressed by discharging the battery, and the internal short-circuit current is also eliminated, so that the safety can be further improved.

Further, according to the present invention, since the communication between the battery and the external circuit is cut off simultaneously with the discharge of the battery, the battery is not affected by the external circuit, and the fault is transmitted to the external circuit. It has none and has the advantage of high reliability.
Further, by providing a current fuse, it is possible to reliably protect the battery from being damaged due to an external short circuit or overload.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a basic configuration of the present invention.

FIG. 2 is a partially cutaway structural view of the secondary battery explosion prevention device according to the embodiment of the present invention, (a) is a front view,
(B) is a front view.

FIG. 3 is an exploded perspective view showing a state in which the secondary battery explosion prevention device shown in FIG. 1 is incorporated in the secondary battery.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Secondary battery explosion prevention device 2 ... Temperature detection means 3 ... Operation switching means 4 ... Discharge means 5 ... Current fuse 6 ... External circuit 7 ... Main body 8 ... Core layer 9 ... Surface thin layer 10 ... Backside thin layer 11 ... Void 12 ... Insulating coating 13 ... Conductive resistance wire 14 ... Core 15 ... Connection terminal plate 16 ... Outer cylinder 17 ... Arc extinguishing agent 18 ... Conductor 19 ... Secondary battery 20 ... Battery case 21 ... Gasket 22 ... Safety valve 23 ... Top cover E: Power supply between positive and negative electrodes

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-10-136581 (JP, A) JP-A-10-255757 (JP, A) JP-A-10-261400 (JP, A) JP-A-10- 302762 (JP, A) JP-A-10-326610 (JP, A) JP-A-8-153536 (JP, A) JP-A-7-99049 (JP, A) JP-A-9-139235 (JP, A) JK 50-6244 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 2/34 H01M 10/02 H01M 10/40 H01M 10/48 301 H02J 7/00

Claims (5)

(57) [Claims] (1) about 1/10 of the internal resistance of a secondary battery
Conductive resistance wire with low resistance is spirally wound around the core.
To convert current to Joule heat and suppress inrush current
Into a current-to-heat converter that generates back electromotive force
And discharge means to be made, the secondary battery and the temperature detecting means for detecting the temperature inside, the positive and negative electrodes a power supply of the previous SL temperature detection means conducts operation in response to outputs a normal temperature signal rechargeable battery Means for forming a closed loop circuit with an external circuit, conducting in response to outputting an abnormal temperature signal, conducting and operating and switching operation means for forming a closed loop circuit between the power supply between the positive and negative electrodes of the secondary battery and the discharging means Is the insulating core layer and the core layer
Three layers, a front thin layer and a back thin layer of the conductor sandwiched between
And a hole as a gas vent hole is provided in the central portion.
To form a thin disk that can be housed in the secondary battery case
This thin disk is stored in the heart layer of the
The main body formed on the body has a thin front layer on the positive terminal and a thin back layer
Are connected to the positive electrode respectively, and
An explosion prevention device for a secondary battery, which is interposed between a safety valve . 2. The explosion preventive device for a secondary battery according to claim 1, wherein a current fuse that cuts off by the flow of the overcurrent and disconnects the conduction between the positive electrode and the positive terminal of the secondary battery is attached to the element member. . 3. The explosion of a secondary battery according to claim 1, wherein said temperature detecting means comprises a temperature sensor such as a thermistor, and said operation switching means comprises a semiconductor non-contact relay having a flip-flop circuit as a logic element. Prevention device. 4. The method according to claim 1, wherein said temperature detecting means is provided on a peripheral wall of said hole.
The secondary battery explosion prevention device according to claim 3, which is provided alongside. 5. The battery according to claim 5 , wherein said discharging means is provided in said hole and in said battery.
Conductivity that extends through the vent hole to the bottom of the battery
The apparatus for preventing explosion of a secondary battery according to claim 4 , wherein the apparatus is connected to a negative electrode of the secondary battery by a body .