JPH06124733A - Secondary battery device - Google Patents

Abstract

PURPOSE:To provide battery performance independent of outside humidity via the control of battery operation humidity, and avoid an ignition accident without exposing a battery directly to the atmosphere, even if a battery housing container is broken, by connecting a heat exchanger to a battery device and covering the outer wall of the device with an insulation material. CONSTITUTION:A cell 1 with the side and bottom covered with a nonaqueous cooling medium 7, is housed a battery housing container 8. While external positive and negative terminals 10 and 11 are being led out, the cell 1 is secured with a battery fastener 9, and the upper side of the cell 1 is concealed with a cover having a vent valve 12. The end of a humidity measurement instrument 13 is inserted in a cooling medium located along the periphery of the container 8, and the container 8 is provided with a heat exchanger 16 for supplying secondary feed water 17. Also, a pump controller 18 is operated, according to the temperature indicated with the instrument 13, and the feed water 17 is circulated through the medium 8 on the operation of a pump 15 connected to the heat exchanger 16. Furthermore, the outer wall of the container 8 is covered with an insulation material not shown herein. According to this construction, a high- output type nonaqueous electrolytic secondary battery can be efficiently cooled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to temperature control of a battery and measures against abnormalities.

[0002]

2. Description of the Related Art The need for temperature control including cooling of a secondary battery increases as the battery scale increases. If a coin type battery or a cylindrical type battery of about AA size is used at the same time, the battery is sufficiently cooled by heat conduction to the battery container and natural cooling, so that cooling equipment is not necessary. . However, an assembled battery that simultaneously operates a plurality of battery blocks, such as a power supply for automobiles and a power storage power supply, generates Joule heat that exceeds the amount of natural cooling heat during charging and discharging. Further, when the charging / discharging time is shortened, the heat generation amount per unit time further increases. For this reason, if the battery temperature exceeds the maximum allowable temperature even locally, the performance and safety of the constituent cells will be significantly reduced. Therefore, when operating a large battery, a cooling device that uniformly cools all the unit cells is essential. To make the battery operating temperature uniform,
It is also desirable for facilitating operation control of the battery.

There are two possible cooling methods for a general battery, a gas cooling method and a liquid cooling method, but in many cases the former is devised because of the ease of handling the refrigerant. Cooling method for stationary high temperature battery using dry inert gas as refrigerant (Japanese Patent Publication No. 4-51472)
Has been published. In addition, a forced air cooling method using a ventilation fan (Japanese Patent Publication No. 4-29186) or a blower (German Patent DE 4029-018-A) has already been proposed to cool the assembled battery.

A non-aqueous electrolyte secondary battery such as a lithium secondary battery is a battery having excellent energy density and output. However, a short circuit between the positive electrode and the negative electrode inside the battery, heat generation due to overcharge or overdischarge, or Due to the decomposition of the electrolytic solution, the internal pressure of the battery rises, which may eventually cause the battery container to burst. At this time, if the battery is directly exposed to the atmosphere, there is a high risk of ignition of the battery. Therefore, in order to cool such a battery, it is necessary to have a cooling method which has high cooling efficiency and at the same time can cope with an accident such as a rupture of the battery container. However, an effective means satisfying both conditions has not yet been found.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a non-aqueous electrolyte secondary battery that takes into consideration the situation where an abnormality occurs inside the battery and the battery container bursts.

[0006]

The present invention has devised a liquid cooling system for a non-aqueous electrolyte battery using a liquid as a refrigerant. However, since most of the battery active materials of the battery targeted by the present invention have extremely high reactivity with water, the liquid refrigerant used is a non-aqueous liquid. If the battery active material is stable to water, there is no problem in using water as a refrigerant in the present invention.

The reason why the liquid cooling method is suitable for cooling a non-aqueous electrolyte battery is as follows. Since liquid has a larger specific heat and thermal conductivity than gas, the battery can be cooled more efficiently. Also, when a battery abnormality such as a short circuit inside the battery occurs and the battery container is destroyed, or when the external battery storage container is opened to replace the defective battery, the atmosphere contacts the battery. There is an advantage that can be avoided.

A specific type of battery to which the present invention is applied is a lithium secondary battery. The sealed unit cell containing the electrode and the electrolytic solution is placed in a container, and the non-aqueous liquid refrigerant is filled up to the upper end of the battery container. The electrode terminal of the unit cell is pulled out to the outside of the container containing the battery and the refrigerant, and the container is sealed. The electrode terminal portion is covered with a coating (polymer or the like) that is not corroded by the refrigerant. Further, by setting the liquid level of the refrigerant below the upper end of the battery container, the refrigerant is prevented from being electrolyzed even if the coating is deteriorated and the terminals are exposed.

As the refrigerant to be used, a substance having a high specific heat, high thermal conductivity and a high boiling point, which does not corrode the single cell container and the container accommodating the single cell, and is not easily subject to thermal decomposition, air oxidation, electrolysis, etc. is suitable. . Furthermore, an electrically insulating liquid is desirable in order to prevent a short circuit between the electrode terminals. For example,
Hydrocarbons such as alkanes, ketones, aprotic non-aqueous liquids such as silicone oils are suitable. In addition, there is a risk of ignition from the damaged battery when some of the stored batteries are ruptured and the batteries that cannot be used are replaced or the batteries are opened and the batteries are removed. Therefore, a liquid that slowly reacts with the negative electrode active material and is converted into a material having low reactivity is also suitable. For example, it is effective to use a lower alcohol such as methanol, ethanol, or ethylene glycol as a refrigerant to convert lithium contained in the negative electrode into lithium alcoholate to reduce the reactivity of the negative electrode active material in the damaged battery. Hydrogen gas generated in this process is collected from a pressure valve attached to the battery container.

A battery employing the liquid cooling system of the present invention is
If the place of installation is an outdoor cool and dark place, it can be sufficiently cooled by natural cooling and convection of the cooling medium even in a stationary state in which the refrigerant is not forced to flow. In order to further improve the cooling efficiency, an agitator, or a liquid circulation pump and a heat exchanger (or radiator) are attached to the secondary battery to circulate the liquid. In this way, the temperature rise of the battery is suppressed.
In addition, a temperature measuring device is installed in the liquid inside the battery container or near the liquid inlet of the heat exchanger, and the measured temperature is converted into an electric signal and transmitted to the heat exchanger to control the liquid temperature. Doing is also an effective means. It is also possible to detect an abnormality in the battery due to a short circuit, reverse charging, etc. from the rise in the liquid temperature. When there is a large change in outside temperature or when it is cold,
By covering a part or the whole of the outer wall of the battery device with a heat insulating material, the battery temperature can be maintained at a normal operating temperature.

[0011]

[Function] By installing a non-aqueous electrolyte secondary battery in a non-aqueous liquid and using a stirrer or a liquid circulation device and a heat exchanger, the amount of cooling heat is increased and a high output type or large capacity type secondary battery is provided. The secondary battery can be cooled efficiently. Further, since the specific heat of the refrigerant is large, the temperature uniformity of the refrigerant bath is good, the constant temperature operation of the battery is possible, and it is useful for stabilizing the battery performance and prolonging its life.

[0012]

Embodiments of the present invention will now be described with reference to the drawings.

[Embodiment 1] FIG. 2 is an external view of an entire unit cell 1 used in the present invention. The battery is hermetically sealed in a box-shaped container 3 made of stainless steel having an air gap 2 in the lower portion (outer dimension including the air gap 2: 200 × 200 × 50 mm), and the positive electrode terminal 4 and the negative electrode terminal 5 are insulated from each other. Is attached to the upper stainless steel top plate. Void 2 at the bottom of the battery
By ensuring that, the refrigerant can also absorb heat from the bottom surface of the battery. In order to connect and fix a plurality of batteries, electrically insulated protrusions 6 were provided at four positions on the top plate.
The electrodes used in this example are LiMn ₂ O ₄ positive electrode and Li-
It was a Pb alloy negative electrode and was collected by a stainless steel wire mesh.
Between the electrodes, a non-woven fabric made of polypropylene (thickness: 50 μm)
A separator impregnated with an iClO ₄ + propylene carbonate electrolytic solution was inserted, and 10 positive electrodes and 9 negative electrodes were alternately connected in parallel to one single cell.

Next, as shown in FIG. 1, a series connection was made in a box-shaped battery storage container 8 (300 × 300 × 250 mm) in which the container cavity was filled with decane (C ₁₀ H ₂₂ ) as a non-aqueous refrigerant. Three unit cells 1 were immersed. In each battery, the above-mentioned protrusion 6 is fitted into the ceramic plate 9 so that each secondary battery 1
Were connected and fixed. The external positive electrode terminal 10, the external negative electrode terminal 11, the gas vent valve 12, and the temperature measuring device 13 insulated from the battery container were attached to the stainless steel top plate of the battery storage container 8. The gas vent valve 12 was installed in order to reduce the increased pressure due to the temperature rise inside the battery container 8 or the gas generation from the unit cell 1.

The battery 1 shown in FIG. 1 was charged and discharged at room temperature for 8 hours, and the temperature of the refrigerant was measured by the temperature measuring device 13. At the end of discharge in each cycle, the temperature of decane increased by about 10 ° C. The increase in the internal pressure of the battery container 8 was extremely small. From this example, it was demonstrated that the decane used did not interfere with the natural cooling of the battery, and the battery was cooled by the outside air.

[Embodiment 2] In order to circulate the refrigerant, an agitator 14 was attached to the battery container 8 of FIG. 1 to assemble a battery device as shown in FIG. The refrigerant was changed to ethanol, and charge / discharge was performed at room temperature for 8 hours while operating the stirrer 14. Refrigerant ethanol has a maximum temperature of 7 ° C
Rose. Forcibly stirring the coolant as in this embodiment improves the cooling efficiency of the battery.

[Embodiment 3] Further, in order to increase the cooling efficiency, a liquid circulation pump 15 and a heat exchanger 16 were installed outside the FIG. 1, and a battery device as shown in FIG. 4 was assembled. The refrigerant 7 was cooled by the secondary supply water 17 at 15 ° C. The temperature of the refrigerant 7 is measured by the temperature measuring device 13, the temperature is converted into an electric signal, and the electric signal is input to the pump controller 18. The flow rate of the refrigerant sent by the pump 15 is controlled according to the measured temperature. Using this apparatus, a silicone oil was used as a refrigerant, and the charge / discharge cycle of 8 hours described in [Example 1] was performed. First, the flow rate of the refrigerant was 2 dm ³ min ^-1 , and all the refrigerant was replaced in about 6 minutes. The temperature rise of the refrigerant in the final stage of discharge of the single cell was suppressed to 1 to 2 ° C., and the cooling efficiency of the cell was significantly improved as compared with [Example 1]. Next, the battery storage container 8 of FIG. 4 was installed in a constant temperature bath kept at 30 ° C., and the same charge / discharge cycle test was performed by changing the rotation speed of the pump 15. The temperature of the refrigerant was dependent on the flow rate of the pumped refrigerant and could be adjusted in the range 15-30 ° C. Even if the heat exchanger used in this example was replaced with a radiator type radiator, the same cooling efficiency was obtained. [Example 4] In order to raise the operating temperature of the battery, the entire surface of the storage container 8 for the unit cells and the refrigerant was covered with a heat insulating material, and the container was set at a place where the outside temperature was 5 ° C. When the secondary supply water at 20 ° C was run,
The temperature of the liquid circulating in the battery container is 18 at the end of charging.
It was 20 ° C at the end of discharge. This example shows that the liquid cooling system of the present invention is effective not only for cooling the battery but also for constant temperature operation of the battery.

[0018]

According to the liquid cooling system of the present invention, a high-power type non-aqueous electrolyte secondary battery can be efficiently cooled. Also,
By installing a heat exchanger in the battery device and covering the outer wall of the device with a heat insulating material, the operating temperature of the battery can be controlled and battery performance independent of the outside air temperature can be obtained. Further, the container containing the electrode and the electrolytic solution is destroyed, so that a battery ignition accident due to the battery being in direct contact with the atmosphere can be avoided, and the safety in the event of a battery abnormality is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a secondary battery device according to an embodiment of the present invention.

FIG. 2 is an external view of a secondary battery device according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a secondary battery device according to an embodiment of the present invention in which a stirrer is installed.

FIG. 4 is a configuration diagram of a secondary battery device according to an embodiment of the present invention in which a liquid circulation pump and a heat exchanger are connected.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Single battery, 2 ... Void part of battery container, 3 ... Single battery container, 4 ... Positive electrode terminal, 5 ... Negative electrode terminal, 6 ... Battery fixing protrusion, 7 ... Non-aqueous refrigerant, 8 ... Battery storage container, 9 ... Battery fixture, 10 ... External positive electrode terminal, 11 ... External negative electrode terminal, 12 ...
Gas vent valve, 13 ... Temperature measuring device, 14 ... Liquid agitator, 15
… Pump, 16… Heat exchanger, 17… Secondary supply water, 18…
Pump controller.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mamoru Mizumoto 4026 Kuji Town, Hitachi City, Hitachi, Ibaraki Prefecture Hitachi Research Laboratory Ltd. (72) Inventor Tatsuo Horiba 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Inside Hitachi Research Laboratory

Claims (6)

[Claims] 1. A secondary battery device comprising one or more battery block groups, wherein at least a part of the battery block group is immersed in a liquid. 2. A secondary battery device, wherein the liquid according to claim 1 is a non-aqueous liquid that does not corrode a battery container. 3. A secondary battery device, wherein the liquid according to claim 1 is a non-aqueous liquid that reacts with an electrode active material. 4. The secondary battery device according to claim 1, wherein the container containing the battery and the liquid is provided with an agitator. 5. The secondary battery device according to claim 1, wherein the liquid is circulated by a pump through a heat exchanger or a radiator installed outside the container containing the battery and the liquid. 6. The secondary battery device according to claim 1, wherein the entire outer wall of the container containing the battery and the liquid, or at least a part of the container is covered with a heat insulating material.