JPH07326548A - Power storage - Google Patents

Abstract

PURPOSE:To provide a power storage having a large electric double layer capacitor in which the effect of an internal short circuit can be minimized. CONSTITUTION:An inner electrode of an electric double layer capacitor of more than hundreds of farads is split into two or more, and each inner electrode C1 to C4 is connected in parallel. Then, current limiting means (e.g. fuse) F1 to F4 are inserted in each current path to the inner electrode C1 to C4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power storage device for electric power,
More specifically, the present invention relates to a power storage device for electric power, which has an electric double layer capacitor having a large capacitance and is used as a power source for an electric vehicle or the like.

[0002]

2. Description of the Related Art Electric double layer capacitors are outstanding in that they have a large capacitance compared to other types of capacitors. Even if there was a short circuit, no serious accident occurred.

[0003]

However, for example, one electric double layer capacitor having an electrostatic capacity of several thousand F is made for an electric vehicle, or a plurality of electric double layer capacitors are connected in parallel to each other. In order to obtain the electrostatic capacity of 1), measures must be taken when a short circuit occurs in the internal electrode.

That is, as the electrostatic capacity increases, the area of the internal electrode also increases, so the probability of a short circuit also increases, and if any part of the internal electrode is short-circuited, the charged electrical Energy is discharged in that area and converted into heat, which results in an increase in internal temperature.

For example, withstand voltage 3V, electrostatic capacity 1000F
The energy P of the electric double layer capacitor of is: P = 0.5 × 1000 × 3 ² = 4500 (joule
s). This heat energy raises the electrolyte solution 100 cc having a specific heat of 0.5 by 22 ° C., for example. Therefore, assuming a case where, for example, 10 electric double layer capacitors having the above ratings are connected in parallel, if a short circuit occurs even in a part of the internal electrodes, the temperature may rise to a dangerous temperature. .

To prevent this, a small electrostatic capacity
For example, a plurality of electric double layer capacitors of about several F may be connected in parallel, and for example, a fuse as a current limiting means may be inserted in each of the capacitors, but to obtain a capacitance of several thousand F as a whole. However, a considerable number of electric double layer capacitors are required, and if a fuse is attached to each of them, it is not preferable in terms of cost and space and is not practical.

The present invention has been made to solve the above problems, and its purpose is to ensure safety even if a short circuit occurs in an internal electrode of an electric double layer capacitor having a large capacitance, and An object is to provide a power storage device for electric power that can be practically used in terms of configuration.

[0008]

In order to achieve the above object, the present invention provides an electric power provided with an electric double layer capacitor having an electrostatic capacity of several hundred F or more or a battery having a capacitor type characteristic of a capacity corresponding to the electric double layer capacitor. In the power storage device for a vehicle, an internal electrode provided therein is divided into two or more, each of which is connected in parallel, and a current limiting means is inserted in an individual current path to each internal electrode. It is characterized by that.

In this case, when the internal electrode is divided into two or more, the capacitance per internal electrode is C (F) and the withstand voltage is V (V), and the electrolytic solution used for the capacitor is The specific heat of the electrolyte solution is d, and the mass of the electrolyte solution is W
(G), the following equation that holds when the rising temperature of the electrolytic solution heated by the energy generated when the internal electrodes are short-circuited is T (° C.), and the rising temperature of the electrolytic solution that is allowed for use in C = 2dWT / V ² . It is rational and preferable to set T to determine the number of divisions of the internal electrodes.

Further, as the current limiting means, it is preferable to use a fusing fuse in terms of simplicity and cost, but in addition, a heat sensitive switch, a heat sensitive relay, or a semiconductor switch having a current detecting function can be self-reset. A switch or the like can be used.

[0011]

As described above, by dividing the internal electrodes and providing the current limiting means for each of them, even if a short circuit occurs in one of the internal electrodes, the current limiting means allows the other internal electrodes to be disconnected from the other internal electrode. Concentration of electrical energy on the internal electrode where the short circuit occurs is prevented.

Further, when dividing the internal electrodes, it is advisable to set the number of divisions reasonably in consideration of the temperature rise that is considered safe as described above. Here, an example will be described according to the above equation. For example, when the specific heat of the electrolytic solution is 0.5, the mass thereof is 300 g, the withstand voltage is 3 V, and the allowable limit of temperature rise at the time of short circuit is set to 40 ° C., the electrostatic capacitance C of the electric double layer capacitor at that time is C = 2 × 0.5 × 300 × 40/9 = 1333 (F). Therefore, if this electric double layer capacitor is regarded as one internal electrode of the power storage device for electric power, and the device as a whole has a capacitance of 5000 F, for example, the internal electrode is divided into four and By inserting the current limiting means into each of them, even if any of the internal electrodes is short-circuited, the temperature rise due to the short circuit can be suppressed within the allowable limit of 40 ° C. However, although the constant of the above formula changes depending on the electrode material, the electrolytic solution, and the value of the allowable temperature rise, it is approximately 500 to
It is preferable to divide in the range of about 5000F.

[0013]

Embodiments of the present invention will be described below with reference to FIG. The electric power storage device according to this embodiment has an electric double layer capacitor P having a withstand voltage of 3 V, an electrostatic capacity of 4000 F, a maximum charge / discharge current of 20 A, and a DC internal resistance of 5 mΩ.
It has S.

In this case, the internal electrode of the electric double layer capacitor PS is divided into four internal electrodes C1 to C4 of 1000 F each, the internal electrodes C1 to C4 are connected in parallel, and each of the current paths thereof is divided. The fusing fuses F1 to F4 are inserted into the respective fuses. In addition, Ta, T
b is a terminal used during charging and discharging.

Since the maximum current during charging / discharging of this electric double layer capacitor PS is 20 A, it is sufficient that each of the divided internal electrodes C1 to C4 can safely bear 5 A each. Therefore, each of the fuses F1 to F
No. 4 does not blow at 5 A, and 400% of the rated current, that is, at 20 A, it is possible to use a normal fusing fuse or a metal foil or the like which is fast blown on the order of several seconds. The fusing fuse may be formed by cutting a part of a metal foil such as an aluminum foil or stainless steel or copper used as a collector electrode inside the capacitor so as to be partially thin, and the part may function as a fuse. .

If the fuses F1 to F4 are not provided, for example, if a short circuit occurs in the internal electrode C1, 18000 joules of the total stored electric energy stored in the electric double layer capacitor PS is concentrated in the internal electrode C1. In the present invention, the fuse F
The electrical energy lost as thermal energy due to the melting of No. 1 is limited to the amount stored in the internal electrode C1, and is 4500 Joules, which is ¼ of the entire electrical energy. Excessive temperature rise is prevented.

To be exact, the energy required to blow the fuse and the energy spent for blowing the fuse are added, but this value is the value for which the fuse is normally designed. If so, the above 4
It is a value that is almost negligible compared to 500 joules.

In the above embodiment, the electric double layer capacitor P
Although S is divided into four internal electrodes C1 to C4, it may be divided into smaller parts depending on safety. For example, if it is divided into eight, the electric energy that is lost as heat energy due to the short circuit of one of the internal electrodes will be half that in the above-mentioned embodiment, and the fusing capacity of the fuse will be half, but on the other hand, Is doubled, and the number of assembling steps in manufacturing is also increased. Therefore, it is not preferable to divide it indiscriminately.

Although one electric double layer capacitor PS is used in the above embodiment, this electric double layer capacitor PS is used.
According to the present invention, since the fuses are inserted in the respective internal electrodes, even if a plurality of themselves are connected in parallel, the electric energy as a whole is not concentrated in the short-circuited internal electrodes, and the thermal energy is reduced. The electrical energy lost as is suppressed to the amount of electricity stored in the short-circuited internal electrode.

The fuse used in the present invention is required not only to have a reliable fusing characteristic but also to have a small internal resistance in a normal state. In the case of this embodiment, since the series internal resistance of the electric double layer capacitor PS is as extremely low as 5 mΩ, it is desirable that the internal resistance of the fuse is negligibly smaller than this.

Further, although the fusing fuse is used as the current limiting means in the above embodiment, a heat sensitive switch, a heat sensitive relay, and a semiconductor switch having a current detecting function can also be used. Is self-recoverable, which is advantageous when, for example, a capacitor having no abnormality is short-circuited by a user's erroneous operation. Even when such a switch is used, it is desirable that the internal resistance thereof be negligibly smaller than the internal resistance of the electric double layer capacitor PS as described above.

The capacity of the fuse F inserted into each of the internal electrodes C divided as described above is determined by the following condition (a).
By determining from (b), it is possible to prevent the fuse from being blown out due to an external short circuit caused by a user's erroneous operation, although the internal electrode is blown out when the short circuit occurs. That is, (a) Even if the terminals Ta and Tb are short-circuited, the internal electrode C does not melt at the current Iy and the amount of electricity with which the internal electrode C is fully charged.

(B) A current Ix that is as small as possible
・ Blows by the amount of electricity.

The internal electrode C1 and its fuse F1 will be described as an example. First, when the terminals Ta and Tb are short-circuited by the user's carelessness, the fuse F1 is charged with the charging voltage of the internal electrode C1 at that time. Although the current Iy determined by the internal resistance R1 structurally included in the wiring and the like flows as long as the amount of electricity of the internal electrode C1 continues, the current capacity and heat capacity of the fuse F1 are designed to withstand this. In this way, even if the terminals Ta and Tb are erroneously short-circuited, there is no possibility that the built-in fuse F1 will blow and the electric double layer capacitor PS will become unusable.

Next, if the internal electrode C1 is short-circuited for some reason, the other internal electrode C2 is connected via the fuse F1.
The current Ix flows from C4. The power in this case is much higher than that in the case of only the internal electrode C1. For example, if it is assumed that the internal electrode C1 has a capacity 10 times or more that of the other internal electrodes, the electrical and thermal capacity of the fuse F1 will be blown out at a rate several times that of the internal electrode C1 alone. By such selection, an electric double layer capacitor PS having a fuse that melts against an internal short circuit of the internal electrode C1 and does not melt due to a short circuit between the terminals Ta and Tb can be obtained.

Although the electric double layer capacitor having a large electrostatic capacity is used in the above embodiment, a battery having a capacitor type characteristic of a capacity corresponding to the electric double layer capacitor may be used.

[0027]

As described above, according to the present invention,
The following effects are achieved. That is, the capacitance is a few
In an electric power storage device comprising an electric double layer capacitor of 00F or more or a battery having a capacitor-type characteristic of a capacity corresponding to the electric double layer capacitor, an internal electrode provided therein is divided into two or more and each of them is connected in parallel. According to the invention as set forth in claim 1, wherein the current limiting means is inserted into each individual current path to each internal electrode.
Even if a short circuit occurs in one of the internal electrodes, the current limiting means prevents the concentration of electric energy from the other internal electrodes to the internal electrode in which the short circuit has occurred, thus ensuring safety.

According to the second aspect of the present invention, the number of divisions of the internal electrodes is rationally determined based on the temperature rise of the electrolytic solution that is allowed for use.

According to the invention as defined in claim 3, wherein the current limiting means is a fusing fuse, it is inexpensive and easily available, which is advantageous in terms of cost.

According to the invention as set forth in claim 4, the current limiting means is a switch capable of self-restoration such as a heat sensitive switch, a heat sensitive relay or a semiconductor switch having a current detecting function. This is advantageous when a short circuit occurs due to an erroneous operation.

[Brief description of drawings]

FIG. 1 is a circuit diagram schematically showing an embodiment of a power storage device according to the present invention.

[Explanation of symbols]

 PS electric double layer capacitor C1 to C4 divided internal electrodes F1 to F4 current limiting means (fuse)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01G 9/12 // H02H 7/16 A 9375-5E H01G 9/00 301 Z 9/12 C

Claims (4)

[Claims] 1. An electric power storage device comprising an electric double layer capacitor having an electrostatic capacity of several hundreds of F or more or a battery having a capacitor-type characteristic of a capacity corresponding to the electric double layer capacitor, wherein two internal electrodes are provided inside the electric power storage device. A power storage device for electric power, characterized in that it is divided into the above parts, each of which is connected in parallel, and a current limiting means is inserted in each individual current path to each internal electrode. 2. When the internal electrode is divided into two or more, the capacitance per internal electrode is C (F).
And its withstand voltage V (V), the specific heat of the electrolytic solution used for the capacitor is d, the mass of the electrolytic solution is W (g), and the rising temperature of the electrolytic solution heated by the energy generated when the internal electrodes are short-circuited. ^{2. The} number of divisions of the internal electrode is determined by setting the rising temperature T of the electrolytic solution that is allowed for use in the following equation, which is satisfied with T (° C.), C = ² dWT / V ² .
The electric power storage device according to. 3. The electric power storage device according to claim 1, wherein the current limiting means is a blow fuse. 4. The switch according to claim 1, wherein the current limiting means comprises a heat-sensitive switch, a heat-sensitive relay, or a switch capable of self-restoration such as a semiconductor switch having a current detection function.
The electric power storage device according to.