JP4224730B2 - Secondary battery device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a secondary battery device provided with a sensor, and more specifically, a secondary battery device for obtaining a high voltage and a large current used for an electric vehicle, a stationary power supply device and the like is provided with a sensor. Thus, the safety and reliability of the secondary battery device can be improved.
[0002]
[Prior art]
As secondary battery devices used in electric vehicles and stationary power supply devices, lead storage batteries and alkaline storage batteries have been used as unit batteries. However, in recent years, lithium batteries that can be made smaller and lighter have a larger capacity. High-capacity lithium secondary batteries that can be charged and discharged have come to be used as unit batteries, and secondary battery devices in which a plurality of these large-capacity lithium secondary batteries are connected directly and in parallel have attracted attention. ing.
[0003]
In such a secondary battery device, characteristics may deteriorate due to heat generation during charging / discharging, or the life may be shortened early. Therefore, a temperature detection unit may be provided in each unit battery to stop charging / discharging when the temperature rises. , So that we can respond appropriately.
[0004]
That is, a thermocouple or a thermistor is used as the temperature detector, and when the temperature rises, the voltage change or resistance change is detected to stop charging / discharging.
[0005]
Further, in the secondary battery device described above, an increase in internal pressure may be recognized as the temperature rises during overcharge. Therefore, a safety valve is provided in each unit battery so that the safety valve can be opened when the internal pressure rises.
[0006]
That is, when the safety valve is opened due to an increase in internal pressure, charging is thereby stopped.
[0007]
[Problems to be solved by the invention]
However, in the secondary battery device described above, when the safety valve does not open due to an increase in internal pressure and the battery case swells, charging is continued, and an unfavorable problem arises in terms of safety such that the battery case ruptures. There was a possibility.
[0008]
In order to solve such a problem, it is possible to attach a pressure sensor to each unit battery and detect the increase in internal pressure of the unit battery to stop charging, but since the pressure sensor is expensive, each unit battery If the pressure sensor is attached to the battery, the cost of the secondary battery device is increased, which is not preferable.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a positive electrode, a separator, and a negative electrode laminated in a battery case are accommodated in a battery case, and a positive electrode terminal drawn from the positive electrode and a negative electrode terminal drawn from the negative electrode In the secondary battery device in which a plurality of unit batteries, in which the battery case is sealed by a lid inserted through the battery, are connected directly and in parallel, the unit battery has a temperature detection unit and a pressure detection unit, and each of the detections The part is provided with a sensor in which one side is provided on a film body having adhesiveness, and each detection unit is connected by a wiring applied to the film body, thereby increasing the temperature. Appropriate measures can be taken at times or when the internal pressure rises.
[0010]
Further, the invention according to claim 2 is the secondary battery device according to claim 1, wherein the temperature detection unit is disposed on at least one of the terminal or the side surface of the battery case, and the pressure detection unit is on the safety valve of the lid or the battery case. It is characterized in that it is arranged on at least one of the side surfaces, so that it is possible to reliably detect the temperature rise of the terminal or the side surface of the battery case, and the safety valve and the side surface of the battery case due to the increase in internal pressure. A change can be reliably detected.
[0011]
The invention of claim 3, wherein, in the secondary battery according to claim 2, wherein the temperature detection unit is formed by providing a thermocouple or thermistor film structure, voltage or resistance caused by a temperature rise The pressure detector is formed by providing a part with a reduced strength in a part of the film body, and the part with the reduced strength is the pressure when the safety valve is opened or the battery case. It is characterized in that the charging is stopped by being blown by the swelling of the battery, and thus charging can be surely stopped not only when the temperature rises but also when the internal pressure rises.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the embodiments.
[0015]
Prior to describing the embodiment of the present invention, a plan view of a sensor attached to a unit battery constituting the secondary battery device of the present invention shown in FIG. 1, and a perspective view of the unit battery shown in FIG. Will be described.
[0016]
In the sensor 20 shown in FIG. 1, the temperature detectors 11 </ b> A and 11 </ b> B and the pressure detectors 12 </ b> A and 12 </ b> B are provided on a film body 13 made of a polyimide sheet having adhesiveness on one side. The temperature detectors 11A and 11B and the pressure detectors 12A and 12B are connected by a wiring 14 provided on the surface.
[0017]
In the unit battery 10 shown in FIG. 2, a pole group 1 in which a positive electrode, a negative electrode, and a separator are stacked is housed in a battery case 2 and sealed by a lid 3. That is, the positive electrode is a mixture of lithium cobaltate as a positive electrode active material, acetylene black as a conductive agent, binder and polyethylene oxide as a gel electrolyte, and a propylene carbonate solution of lithium hexafluorophosphate as an electrolyte. The negative electrode is made of carbon powder as the negative electrode active material and polyethylene oxide as the gel electrolyte. A mixture obtained by kneading a propylene carbonate solution of lithium hexafluorophosphate as an electrolyte solution was applied to both sides of a current collector made of a copper foil having a size of 363 mm × 169 mm. Polyethylene oxide is layered and the negative electrode is located on the outermost side In this way, 31 positive electrodes and 32 negative electrodes are laminated. A positive electrode terminal 4 is drawn from the positive electrode of the pole group 1, and a negative electrode terminal 5 is drawn from the negative electrode.
[0018]
The pole group 1 has a width of 388 mm, a height of 175 mm, a depth of 14.5 mm, and is accommodated in a rectangular battery case 2 made of aluminum having a thickness of 1 mm, and the lid 3 is laser welded. While being sealed, the insertion part of each terminal is sealed by arranging a packing made of polyethylene in the insertion part of the positive electrode terminal 4 and the negative electrode terminal 5 of the lid 3. In addition, 6 is a safety valve provided on the lid 3, and 7 is a protrusion formed on the surface of the battery case 2 and the lid 3.
[0019]
The temperature detectors 11A and 11B of the sensor 20 shown in FIG. 1 are formed by providing a thermocouple or thermistor on the film body 13, and the pressure detectors 12A and 12B are cut to reduce the strength. The temperature detector 11A is disposed on one of the positive electrode terminal 4 and the negative electrode terminal 5, the temperature detector 11B is disposed on the side surface of the battery case 2, and the pressure detector 12A is covered with a lid. 3 is disposed on the safety valve 6, and the pressure detector 12 </ b> B is disposed on the side surface of the battery case 2. Then, a change in the temperature of the thermocouple or a change in the resistance of the thermistor due to a temperature rise is detected to stop charging and discharging, and the above-described strength is obtained by the pressure when the safety valve 6 is opened or the swelling of the battery case 2. The reduced portion is cut and the wiring 14 is cut to stop charging. In addition, the part which reduced this intensity | strength is made into the intensity | strength which breaks with the tensile force of 1 kgf or less, and if the elongation of the wiring 14 at the time of a fracture | rupture shall be 1 mm or less, it will stop charge at the initial stage of a deformation | transformation of the battery case 2. Therefore, it is preferable in terms of safety.
[0020]
Next, when the test battery in which the sensor 20 is attached to the unit battery 10 described above is put into a thermostat and the temperature is increased to 20 ° C., 40 ° C., 60 ° C., the battery temperature detected by the sensor 20 is increased. It was found that there is a certain correlation between the change and the temperature change in the thermostat.
[0021]
Based on this, when the test battery is continuously charged at 0.1 C without forced cooling, the sensor 20 detects that the temperature change is 2 ° C./min or more and stops charging. It was found that the test battery can be almost fully charged. Also, if this test battery is overdischarged at 0.05 C, the sensor 20 detects that the temperature change is 2 ° C./min or more and is set to stop the discharge, the test battery is It was found that it was not adversely affected by overdischarge. In addition, when the battery for test was not forcibly cooled and the temperature detectors 11A and 11B of the sensor 20 were not operated, and continuously charged at 0.1 C, the internal pressure increased at the end of charging, and the safety valve 6 It was found that the wiring 14 of the sensor 20 was disconnected at the same time as the valve was opened, and charging could be stopped. Further, the test battery is subjected to a charge / discharge cycle of 0.1 C charge and 1 C discharge, and the sensor 20 detects that the temperature change has become 2 ° C./min or more and stops charging. It was found that the charge / discharge cycle life was 100 cycles or more.
[0022]
Next, a plan view of the sensor according to the embodiment of the present invention shown in FIG. 3 and a perspective view of the secondary battery device according to the embodiment of the present invention shown in FIG. 4 will be described.
[0023]
The sensor 200 shown in FIG. 3 includes a plurality of wirings 14 provided on the film body 13, cuts out the wirings by the number of unit cells, and has a temperature detection unit 11A, a pressure detection unit 12A, and a temperature detection unit at one end. 11B and the pressure detection unit 12B are cut halfway, and the temperature detection unit 11A, the pressure detection unit 12A, the temperature detection unit 11B, and the pressure detection unit 12B are bent at substantially right angles.
[0024]
The secondary battery device 100 shown in FIG. 4 has eight unit cells 10 connected in series, and the projections 7 on the side surfaces of the battery case 2 are in contact with each other between adjacent unit cells 10 to increase the cooling effect by ventilation. The temperature detection unit 11A of the sensor 200 is disposed on the positive terminal 4 of each unit battery 10 and the pressure detection unit 12A is disposed on the safety valve 6 so that the temperature is The detection unit 11 </ b> B and the pressure detection unit 12 </ b> B are arranged on the side surface of the battery case 2 of each unit battery 10.
[0025]
In the above-described embodiment, the case where the sensor including both the temperature detection unit and the pressure detection unit is used in a secondary battery device in which the unit battery is a large-capacity lithium secondary battery has been described. Depending on the situation, a sensor having one of the temperature detection unit and the pressure detection unit may be used, the temperature detection unit may be disposed only on one of the terminals or the side surface of the battery case, and the pressure detection unit may be mounted on the safety valve or on the battery. You may arrange | position only to one of the side surfaces of a tank.
[0026]
As described above, in the inventions according to claims 1 to 3, since the temperature detection unit and the pressure detection unit are provided on the film body as a sensor, it contributes to the cost reduction of the secondary battery device including the sensor. In addition, it is possible to contribute to obtaining a secondary battery device capable of appropriately responding to both cases of temperature rise and internal pressure rise.
[Brief description of the drawings]
FIG. 1 is a plan view of a sensor attached to a unit battery constituting a secondary battery device of the present invention.
FIG. 2 is a perspective view of the unit cell shown in FIG.
FIG. 3 is a plan view of a sensor according to an embodiment of the present invention.
FIG. 4 is a perspective view of a secondary battery device according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electrode group 2 Battery case 3 Lid 6 Safety valve 10 Unit battery 11A, 11B Temperature detection part 12A, 12B Pressure detection part 13 Film body 14 Wiring 20 Sensor 100 Secondary battery apparatus 200 Sensor

Claims (3)

  A unit battery comprising a battery case in which a pole group in which a positive electrode, a separator, and a negative electrode are stacked is housed, and the battery case is hermetically sealed by a lid through which a positive electrode terminal drawn from the positive electrode and a negative electrode terminal drawn from the negative electrode are inserted. In the secondary battery device in which a plurality of units are connected in series and in parallel, the unit battery has a temperature detection unit and a pressure detection unit, and each detection unit is provided on a film body having one surface having adhesiveness, And the secondary battery apparatus characterized by having the sensor by which each detection part is connected by the wiring given to the said film body. 2. The secondary battery device according to claim 1, wherein the temperature detection unit is disposed on at least one of the terminal or the side surface of the battery case, and the pressure detection unit is disposed on the safety valve of the lid or at least one of the side surface of the battery case. A secondary battery device. 3. The secondary battery device according to claim 2, wherein the temperature detection unit is formed by providing a thermocouple or a thermistor on the film body, and is configured to detect a change in voltage or resistance due to a temperature rise and stop charging / discharging. At the same time, the pressure detection part is formed by providing a part with a reduced strength in a part of the film body, and the part with the reduced strength is cut by the pressure at the time of opening the safety valve or the swelling of the battery case to stop charging. A secondary battery device characterized by being configured as described above.

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