JP2002343325A - Safety valve and safety valve system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safety valve which turns into an open state the instant an inner short-circuit occurs in a secondary battery. SOLUTION: The safety valve 30 is structured with wire rods 32 for fusion wire arranged in a ring shape on a resin plate 31, and end parts 32a, 32b are exposed to the outside of the resin plate 31. This safety valve 30 is fitted to a vessel of a lithium secondary battery. When generation of short-circuiting trouble is detected by a detecting circuit, current is passed to the wire rods 32. Then, the wire rods and resin in the vicinity fuse, so that the safety valve 30 is opened, and pressure release can be made. Therefore, pressure release is made the instant short-circuit occurs, so that abnormal temperature rise or battery burst can be surely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety valve and a safety valve system, and is useful, for example, as a safety valve provided in a container of a lithium secondary battery.

[0002]

2. Description of the Related Art Lithium secondary batteries have been developed and spread as high energy density batteries. This lithium secondary battery is not limited to a small and small-capacity battery for electronic devices, but also a large-sized and large-capacity battery for emergency power supply facilities and power storage in factories and hospitals, or for powering electric vehicles. Is being developed.

FIG. 9 shows a large box-shaped lithium secondary battery 10.
It is shown. In FIG. 9, 1 is a container, 2 is a positive electrode, 3 is a negative electrode, 4 is a separator, 5 is a positive terminal, 6 is a negative terminal, and 7 is a safety valve. This lithium secondary battery 10
In this case, the container 1 is filled with an electrolytic solution of an organic material (not shown).

[0004] Such a lithium secondary battery 10 is shown in FIG.
As shown in FIG. 2, a plurality of (four in this example) lithium secondary batteries 10 are housed in a frame 20, and the plurality of lithium secondary batteries 10 are connected in series or in parallel to be used as a module battery. .

A charge / discharge control circuit for charging / discharging the lithium secondary battery 10 detects a short-circuit failure of the lithium secondary battery 10 and stops charging / discharging when a short-circuit failure occurs. I am trying to do it.

In such a lithium secondary battery 10, when a short circuit occurs, the short-circuited portion generates heat, and the heat decomposes and gasifies the electrolytic solution, causing the pressure inside the battery to rise rapidly. When the internal pressure is increased as described above, the battery may explode, or the electrolyte explodes due to the explosion of the battery, or the peripheral devices may be damaged. Then, the pressure in the container 1 for hermetically containing the electrode plate and the like rises, and when the pressure exceeds a predetermined value, the safety valve 7 breaks to open, releasing the gas to the outside and releasing the pressure. I have. This avoids the worst case of battery explosion.
Battery abnormalities that cause the electrolyte to heat and generate gas to increase the internal pressure of the battery include an internal short circuit, an external short circuit, an overcurrent input, and an excessive temperature rise.

[0007]

The conventional safety valve 7 is mechanically broken and opened when the pressure inside the battery exceeds a predetermined pressure and the difference between the internal pressure and the external pressure exceeds a predetermined value. It is in a state. For this reason, the safety valve 7 will not be opened unless a short circuit or the like occurs and the thermal runaway progresses and the internal pressure actually rises sharply.

However, from the viewpoint of battery protection, it is desirable to operate the safety valve as early as possible when thermal runaway of the battery material has started. However, since the safety valve is opened by mechanical rupture, the strength cannot be set so that the safety valve is opened even when the internal pressure is low. The reason is that if the operating pressure of the safety valve is excessively reduced, the safety valve is operated (opened) only by a change in the battery internal pressure due to normal charging and discharging, which is not practical.

In view of the above prior art, the present invention provides a safety valve that is opened immediately before an internal pressure actually rises abnormally when an abnormality that causes an increase in the internal pressure of the container occurs. Aim. This safety valve can be applied not only to a safety valve of a non-aqueous electrolyte secondary battery such as a lithium secondary battery, but also to a safety valve provided in various containers whose internal pressure increases when an abnormality occurs.

[0010]

A safety valve according to the present invention which solves the above-mentioned problems is provided with a safety valve which is opened when the pressure in the container becomes higher than a predetermined pressure. The present invention is characterized in that a wire made of a fusible metal which melts when a current is applied is exposed to the outside, and another portion of the wire is sealed inside a resin plate.

Further, the safety valve of the present invention is a safety valve provided in a container of a secondary battery, the valve being opened when the pressure in the container becomes higher than a predetermined pressure. It is characterized in that the other end of the wire is sealed in a resin plate while exposing both ends of the wire made of a fusible metal that melts when flowing.

Further, in the configuration of the safety valve according to the present invention, the wire sealed inside the resin plate is wired in an annular, spiral or meandering shape.

The safety valve according to the present invention is characterized in that a slit groove is formed in the resin plate so that the resin plate is easily broken by an internal pressure of the container.

Further, the safety valve system of the present invention is provided in a container of a secondary battery, and exposes both ends of a wire made of fusing metal which is blown off when an electric current is applied to the outside while simultaneously exposing the other end of the wire. A safety valve having a portion sealed in a resin plate, abnormality detection means for detecting an abnormality that causes an increase in the internal pressure of the container, and, when an abnormality is detected by the abnormality detection means, from both ends of the wire. And a current supply means for supplying a current to the wire.

In the safety valve system according to the present invention, the abnormality detecting means may detect an abnormality based on a voltage between terminals of the secondary battery, a container internal pressure, a container temperature, a generated magnetic field, or a container distortion. Features.

The safety valve system according to the present invention is characterized in that the secondary battery is a non-aqueous electrolyte secondary battery.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a plan view showing a safety valve 30 according to a first embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II of FIG.
FIG. 3 is a sectional view taken along line III-III of FIG. As shown in these figures, the safety valve 30 is configured by enclosing a wire 32 made of a fusible metal in a resin plate 31. The wire rod 32 is arranged in an annular shape and has both ends 32.
a and 32b are exposed outside the resin plate 31.

As a material of the resin plate 31, for example, polyolefins such as polyethylene and polypropylene can be adopted. Further, a wire 32 made of a fusing metal is used.
For example, a fuse material, a low melting point metal such as pure tin or pure lead, a relatively thin copper wire, an aluminum wire, or the like can be used. Since such a material is used, the wire 3
2, the wire 32 is blown, and a portion of the resin plate 31 near the wire 32 is blown.
Is broken, and the safety valve 30 is opened.

As shown in FIG. 4, such a safety valve 30 is disposed inside the upper lid 1a of the container 1 when applied to, for example, a lithium secondary battery. In this case, safety valve 3
An electric wire 40 is connected to the wire 32 of No. 0. When an internal short circuit or the like occurs, a current is supplied to the wire 32 via the electric wire 40 and the safety valve 30 is opened.

FIG. 5 shows a safety valve 30A according to a second embodiment of the present invention. In this safety valve 30 </ b> A, an annular slit groove 33 is formed on the surface side of the resin plate 31. Therefore, in the safety valve 30A, even when no current flows through the wire 32, when the internal pressure of the container increases, the slit groove 33 is mechanically broken, and the safety valve 30A is opened. Can be The configuration of other parts is the same as that of the first embodiment shown in FIG.

FIG. 6 shows a safety valve 30B according to a third embodiment of the present invention. In this safety valve 30 </ b> B, a wire 32 to be sealed in a resin plate 31 is spirally arranged. FIG. 7 shows a safety valve 30C according to a fourth embodiment of the present invention. In the safety valve 30C, the wires 32 sealed in the resin plate 31 are arranged in a meandering manner.
The configuration of other parts is the same as that of the first embodiment shown in FIG.

Next, a safety valve system according to a fifth embodiment of the present invention will be described with reference to FIG. As shown in the figure, the upper lid 1 of the container 1 of the lithium secondary battery 10
a is provided with a safety valve 30. The positive electrode terminal 5 and the negative electrode terminal 7 of the lithium secondary battery 10 are connected to a charge / discharge control circuit 50 via an electric wire 51, and the lithium secondary battery 10 is charged or discharged by the charge / discharge control circuit 50. Is made. The voltage detection circuit 52 detects the voltage between the positive and negative terminals 5 and 7 and sends the detected voltage signal α to the charge / discharge control circuit 50.

In the charge / discharge control circuit 50, the detection voltage signal α
, The voltage of the lithium secondary battery 10 and the rate of change in voltage are monitored. On the other hand, when an internal short circuit occurs in the lithium secondary battery 10, the battery internal voltage sharply decreases. For this reason, the charge / discharge control circuit 50 monitoring the voltage and the voltage change rate of the lithium secondary battery 10 can detect that an internal short circuit has occurred. As described above, when the occurrence of the internal short circuit is detected, the charge / discharge control circuit 50 stops the charge / discharge operation.

The above-described charge / discharge control circuit 50 and voltage detection circuit 52 are conventional ones.
52 also functions as abnormality detection means for monitoring a short circuit or the like of the lithium secondary battery 10.

Further, in the present embodiment, the current supply circuit 55
It also has. The current supply circuit 55 is connected to the wire 32 of the safety valve 30 via the electric wire 40. When the charge / discharge control circuit 50 detects an internal short circuit, the current supply circuit 55 immediately supplies a current to the wire 32 of the safety valve 30. Therefore, as soon as an internal short circuit occurs, the wire 32 is melted and the safety valve 30 is opened.

Therefore, even if an internal short circuit occurs, before the internal pressure of the lithium secondary battery 10 becomes extremely large and immediately before the explosion, that is, before the pressure at which the conventional mechanical safety valve is opened, The safety valve 30 is opened, and the internal gas and electrolyte can be discharged to the outside. Therefore, even if an internal short circuit occurs, an abnormal temperature rise of the lithium secondary battery 10 can be suppressed. This not only enhances the safety of the unit cell, but also reduces the influence of heat on other healthy cells, thereby contributing to the improvement of the safety of the entire power storage system. In particular, a plurality of lithium secondary batteries 10
It is an effective safety system in a power storage system using

In FIG. 8, the safety valves 30A, 30B and 30C shown in FIGS. 5 to 7 can be used instead of the safety valve 30.

In the embodiment shown in FIG. 8, the voltage detection circuit 52
Abnormality is detected by detecting the voltage of the container 1, the internal pressure of the container 1, the temperature of the container 1, the magnetic field resulting from the short-circuit current, the distortion of the container 1, and the supply current are detected by the sensor. Thus, an abnormality may be detected. When detecting various abnormalities that cause the internal pressure of the container 1 to rise (internal short-circuit, external short-circuit, excessive current, excessive temperature rise), the voltage detection circuit 52 stops charging and discharging, and also detects the current supply circuit 55 Accordingly, a current can flow through the wire 32 of the safety valve 30 to open the safety valve 30.

The above-described safety valves 30, 30A, 30
B and 30C are applicable as safety valves provided in containers for aqueous electrolyte batteries such as electrolytic capacitors, lead batteries, and nickel-hydrogen batteries in addition to containers for non-aqueous electrolyte secondary batteries such as lithium secondary batteries. Can be.

[0031]

As described above in detail with the embodiments, the safety valve according to the present invention is provided in a container such as a secondary battery, and when the pressure in the container becomes higher than a preset pressure. A safety valve that is opened by being broken, wherein both ends of a wire made of a fusible metal that melts when an electric current flows are exposed to the outside, and another portion of the wire is sealed inside a resin plate. And In this case, the wire material sealed inside the resin plate may be wired in an annular, spiral, or meandering shape, or a slit groove may be formed in the resin plate to easily break the resin plate due to the internal pressure of the container. Configuration.

[0032] With this configuration, the safety valve can be opened by applying an electric current to the wire, and the pressure can be released before the internal pressure of the container becomes a dangerous pressure. Increase.

Further, in the safety valve system according to the present invention, both ends of the wire made of a fusible metal, which is provided in the container of the secondary battery and melts when an electric current is applied, are exposed to the outside, and the other part of the wire is removed. A safety valve sealed inside the resin plate, abnormality detection means for detecting an abnormality that causes an increase in the internal pressure of the container, and, if an abnormality is detected by the abnormality detection means, a wire is applied from both ends of the wire. And a current supply means for supplying a current. In this case, the abnormality detection means is based on a voltage between terminals of the secondary battery, a container internal pressure, a container temperature, a generated magnetic field, or a container distortion.
Detect abnormalities. Further, the secondary battery was configured to be a non-aqueous electrolyte secondary battery.

With this configuration, when an abnormality such as an internal short circuit, an external short circuit, or an overcurrent input occurs, the battery can be opened more quickly than the conventional safety valve, and the electrolyte is quickly discharged out of the battery. It is possible to suppress abnormal temperature rise, and to enhance the safety of the secondary battery.

[Brief description of the drawings]

FIG. 1 is a plan view showing a safety valve according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG. 1;

FIG. 4 shows a safety valve according to the first embodiment of the present invention.
FIG. 4 is a cross-sectional view illustrating a state where the lithium secondary battery is provided.

FIG. 5 is a sectional view showing a safety valve according to a second embodiment of the present invention.

FIG. 6 is a plan view showing a safety valve according to a third embodiment of the present invention.

FIG. 7 is a plan view showing a safety valve according to a fourth embodiment of the present invention.

FIG. 8 is a configuration diagram showing a safety valve system according to a fifth embodiment of the present invention.

FIG. 9 is a cutaway perspective view showing a lithium secondary battery.

FIG. 10 is a perspective view showing a module battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 7 Safety valve 10 Lithium secondary battery 30, 30A, 30B, 30C Safety valve 31 Resin plate 32 Wire 32a, 32b End 33 Slit groove 40 Electric wire 50 Charge / discharge control circuit 51 Electric wire 52 Voltage detection circuit 55 Current supply circuit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomoo Akiyama 5-717-1, Fukabori-cho, Nagasaki-shi, Nagasaki Sanishi Heavy Industries, Ltd. Nagasaki Research Institute (72) Inventor Hidehiko Tajima 1-1-1, Akunoura-cho, Nagasaki-shi, Nagasaki No. Mitsubishi Heavy Industries, Ltd. Nagasaki Shipyard (72) Inventor Takayoshi Tanaka 5-717-1, Fukahori-cho, Nagasaki-shi, Nagasaki F-term (reference) 5H012 AA07 BB02 DD01 DD05 DD06 DD11 EE01 EE04 FF01 FF03 JJ01 JJ08 JJ10 5H029 AJ12 AM01 BJ02 BJ27 DJ02 EJ01 EJ12 HJ14 HJ15

Claims (7)

[Claims] 1. A safety valve provided in a container, which is opened when the pressure in the container becomes higher than a preset pressure, and which is opened when an electric current is applied. A safety valve characterized in that the other end of the wire is sealed inside a resin plate while both ends are exposed to the outside. 2. A safety valve provided in a container of a secondary battery, wherein the safety valve breaks and opens when a pressure in the container becomes higher than a preset pressure, and is blown when an electric current is applied. A safety valve characterized in that the other end of the wire is sealed inside a resin plate while both ends of the wire are exposed to the outside. 3. The safety valve according to claim 1, wherein the wire material sealed inside the resin plate is wired in an annular, spiral, or meandering shape. 4. The method according to claim 1, 2 or 3.
3. The safety valve according to claim 1, wherein the resin plate is provided with a slit groove for easily breaking the resin plate by an internal pressure of a container. 5. A wire provided in a container of a secondary battery, wherein both ends of a wire made of a fusible metal that melts when an electric current flows are exposed to the outside, and another portion of the wire is sealed in a resin plate. A safety valve comprising: an abnormality detection unit that detects an abnormality that causes an increase in the internal pressure of the container; and a current supply unit that, when an abnormality is detected by the abnormality detection unit, causes a current to flow from both ends of the wire to the wire. And a safety valve system comprising: 6. The apparatus according to claim 5, wherein the abnormality detecting means detects an abnormality based on a voltage between terminals of the secondary battery, a container internal pressure, a container temperature, a generated magnetic field, or a container distortion. Safety valve system. 7. The safety valve system according to claim 5, wherein the secondary battery is a non-aqueous electrolyte secondary battery.