JP2008004270A - Generated gas collecting method of secondary battery, and secondary battery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To exhaust generated gas in an inside of a secondary battery cell to suppress an increase of an inner pressure of the cell caused by accumulation of the generated gas in the inside of the secondary battery cell. <P>SOLUTION: Substituted gas is distributed in the inside of the secondary battery cell, and the gas generated in the inside of the secondary battery cell is exhausted and is collected. Thereby, the increase of the inner pressure of the cell caused by the accumulation of the generated gas in the inside of the secondary battery cell can be suppressed. The substituted gas preferably has a molecular weight greater than that of the gas to be collected in the generated gas. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a secondary battery generated gas collecting method and a secondary battery device for collecting and discharging gas generated in a secondary battery from the inside of the secondary battery.

  Secondary batteries that can be charged and discharged are used, for example, as power sources for automobiles, power supplies for various cordless devices, and the like. A lithium ion secondary battery, which is a typical secondary battery, includes carbon as a negative electrode, an electrolyte as a lithium ion conductor composed of an aprotic organic solvent and a lithium salt, and reversibly and electrically And a positive electrode active material that can be taken in and out.

  In secondary batteries such as lithium ion batteries, during normal use or overcharge or overdischarge, the electrolyte is consumed and various gases are generated by electrolysis. When this generated gas accumulates in the secondary battery cell, the internal pressure of the battery cell may increase.

  For example, in Patent Document 1, each cell constituting a battery is provided with a gas release valve that discharges a gas having a predetermined pressure or higher generated during overcharge / discharge in the battery, and is connected to an ion exchange resin device through a conduit. To capture a gaseous or mist-like electrolyte accompanying the above. The generated gas is discharged into the atmosphere through an explosion-proof filter after the electrolytic solution is captured in the ion exchange resin apparatus.

  In Patent Document 2, a temporary gas discharge valve is provided in the secondary battery case to remove the gas generated inside the case during the battery manufacturing stage, and the temporary gas is formed as soon as the battery is completely formed. Removing the discharge valve and sealing the case, and enclosing the secondary battery case in a housing that is an inert gas environment in the battery manufacturing stage, sucking the inside of the housing with a pump, and sealing the housing after the battery manufacturing is completed Describes the removal of gas generated in the battery manufacturing stage.

  Patent Document 3 discloses a battery cell having a gas discharge valve on its upper surface, a battery box for storing a plurality of battery cells arranged in a row, and a gas inflow portion provided below the battery box. And a gas discharge part provided on the upper side of the battery box, and the gas supply means forcibly supplies the gas from the gas inflow part to the gas introduction passage between the battery cells, and the gas discharge means The electric vehicle that can forcibly exhaust the gas discharged from the gas discharge valve into the battery box together with the gas that has passed through the gas introduction passage. A battery is described.

  Patent Document 4 discloses a gas venting structure for releasing gas that accompanies repeated charging / discharging of a secondary battery, which is lower than the operating pressure of a safety valve of the secondary battery, and of the secondary battery by repeated charging / discharging. A gas venting structure is described in which an on-off valve that opens at a predetermined pressure higher than the internal pressure is provided. In this gas venting structure, by setting the inside of the exhaust system to an inert gas atmosphere, the backflow of the outside air when the on-off valve is opened can be reduced, and deterioration of the electrolyte can be prevented.

JP 11-339747 A JP 2002-289162 A JP-A-7-320794 JP 2004-39337 A

  However, in the methods of Patent Documents 1 to 4, it is difficult to completely discharge the generated gas inside the cell of the secondary battery, and the generated gas is accumulated inside the secondary battery cell and the internal pressure of the cell increases. May end up.

  The present invention collects the generated gas of the secondary battery that discharges the generated gas inside the cell of the secondary battery and can suppress the increase in the internal pressure of the cell due to the accumulated gas inside the secondary battery cell. A method and a secondary battery device.

  The present invention relates to a method for collecting generated gas of a secondary battery that collects gas generated in the secondary battery, and from the inside of the secondary battery by circulating a replacement gas inside the secondary battery. The generated gas is discharged and collected.

  Moreover, in the generated gas collection method of the said secondary battery, it is preferable that the said replacement gas has a molecular weight larger than the collection object gas in the said generated gas.

  In the method for collecting generated gas of the secondary battery, the replacement gas is preferably at least one selected from nitrogen gas or rare gas.

  In the method for collecting generated gas of the secondary battery, the gas to be collected is preferably at least one of hydrogen gas and carbon monoxide.

  Moreover, in the method for collecting generated gas of the secondary battery, the secondary battery is preferably a lithium ion battery.

  The present invention is also a secondary battery device for collecting a gas generated in a secondary battery, wherein a replacement gas is circulated in the secondary battery and the generated gas is discharged from the secondary battery. Replacement gas flow means for generating gas, and generated gas collecting means for collecting the generated gas.

  Moreover, in the secondary battery device, it is preferable that the generated gas collecting means is installed above an installation position of the replacement gas circulation means and the secondary battery.

  In the secondary battery device, it is preferable that the generated gas collecting means is detachable.

  In the secondary battery device, it is preferable that the replacement gas has a molecular weight larger than that of the gas to be collected in the generated gas.

  In the secondary battery device, it is preferable that the replacement gas is at least one selected from nitrogen gas or rare gas.

  In the secondary battery device, it is preferable that the collection target gas is at least one of hydrogen gas and carbon monoxide.

  In the secondary battery device, the secondary battery is preferably a lithium ion battery.

  In the present invention, the generated gas is accumulated inside the secondary battery cell by circulating the replacement gas inside the secondary battery cell and discharging and collecting the gas generated inside the secondary battery cell. The increase in the internal pressure of the cell due to this can be suppressed.

  Embodiments of the present invention will be described below.

  An outline of an example of a secondary battery device according to an embodiment of the present invention is shown in FIG. The secondary battery device 1 includes a secondary battery cell 10, a replacement gas supply cylinder 12 and a replacement gas circulation pipe 14 that are replacement gas circulation means, and a generated gas collector 16 that is a generation gas collection means. In FIG. 1, the secondary battery cell 10 is configured by four secondary battery cells 10 </ b> A to 10 </ b> D, but the number of cells can be arbitrarily set according to the required electric energy.

  In the secondary battery device 1 of FIG. 1, the replacement gas flow pipe 14 includes a replacement gas discharge port 22D of the secondary battery cell 10D, a replacement gas inlet 20A of the secondary battery cell 10A, and a replacement gas discharge of the secondary battery cell 10A. The outlet 22A and the replacement gas inlet 20B of the secondary battery cell 10B, the replacement gas outlet 22B of the secondary battery cell 10B, the replacement gas inlet 20C of the secondary battery cell 10C, and the replacement gas outlet 22C of the secondary battery cell 10C And the replacement gas inlet 20D of the secondary battery cell 10D are connected to each other. The replacement gas circulation pipe 14 between the secondary battery cell 10D and the secondary battery cell 10A is provided with a pump 24 that also functions as a replacement gas circulation means for circulating the replacement gas, so that the replacement of the secondary battery cell 10D is performed. The gas discharge port 22D is connected to the suction side of the pump 24 via a valve 32, and the discharge side of the pump 24 is connected to the replacement gas inlet 20A of the secondary battery cell 10A. The replacement gas supply cylinder 12 is connected to the replacement gas flow pipe 14 between the secondary battery cell 10 </ b> D and the pump 24 by a pipe 26 through a valve 18. The generated gas collector 16 is connected to the replacement gas flow pipe 14 between the secondary battery cell 10 </ b> D and the connection portion of the replacement gas supply cylinder 12 by a pipe 30 through a valve 28. The arrangement position of the pump 24, the connection position of the replacement gas supply cylinder 12 and the generated gas collector 16, and the like are not limited thereto.

  The generated gas collection method of the secondary battery and the operation of the secondary battery device 1 according to the present embodiment will be described with reference to FIG.

  When the secondary battery cell 10 is stopped, the replacement gas supplied from the replacement gas supply cylinder 12 is introduced into the replacement gas flow pipe 14 with the valve 18 opened and the valve 32 closed. 20A is introduced into the secondary battery cell 10A. The replacement gas introduced into the secondary battery cell 10A is discharged from the replacement gas discharge port 22A along with the generated gas generated inside the secondary battery cell 10A. Similarly, the replacement gas discharged from the replacement gas discharge port 22A passes through the inside of the secondary battery cells 10B to 10D together with the generated gas generated inside the secondary battery cells 10B to 10D, and then the replacement gas is discharged. The gas is discharged from the outlet 22D and collected in the generated gas collector 16 with the valve 28 open. At this time, in order to efficiently discharge the generated gas, a predetermined amount of replacement gas is introduced into the replacement gas flow pipe 14, and then the valve 32 is opened and the valves 18 and 28 are closed, so that the replacement gas flows. It is preferable to circulate in the tube 14 and the secondary battery cell 10 for a predetermined time, and then collect in the generated gas collector 16.

  The mixed gas of the collected replacement gas and generated gas is generated in the generated gas collector 16 or in another gas separation device (not shown) connected to the generated gas collector 16 (not shown). The generated gas thus separated is discharged to the outside of the secondary battery device 1. On the other hand, the separated replacement gas may be supplied to the replacement gas supply cylinder 12 and used again as the replacement gas. In this way, by using the replacement gas to discharge the generated gas inside the secondary battery cell to the outside of the cell, the generated gas can be discharged almost without accumulating inside the cell.

  As described above, the mixed gas of the replacement gas and the generated gas is collected by the generated gas collector 16, and the other gas separation device connected to the generated gas collector 16 or to the generated gas collector 16. Etc., the gas is separated into a replacement gas and a generated gas. The method for separating the replacement gas and the generated gas is not particularly limited, and examples thereof include a method of separating using a mass difference between the replacement gas and the generated gas, a method using a separation membrane, and a method using chromatographic separation. . Among these, the method of separating using a mass difference is preferable in that it is not necessary to use a special apparatus.

  In the present embodiment, the replacement gas preferably has a molecular weight larger than that of the gas to be collected in the generated gas. Thereby, the generated gas inside the secondary battery cell, in particular, the generated gas accumulated in the lower part of the cell can be replaced with the replacement gas and easily discharged to the outside of the cell. When the replacement gas has a molecular weight smaller than the gas to be collected in the generated gas, the generated gas tends to accumulate in the lower part inside the cell, and it may be difficult to discharge the generated gas to the outside of the cell. Further, when the generated gas collector 16 separates by using the mass difference between the replacement gas and the generated gas, the gas to be collected in the generated gas is collected upward.

When the secondary battery cell is, for example, a lithium ion battery, the generated gas generated inside the secondary battery cells 10A to 10D during normal use or overcharge / discharge is usually hydrogen (H ₂ , molecular weight 2.0158), one Carbon oxide (CO, molecular weight 28.0104), carbon dioxide (CO ₂ , molecular weight 44.0098), methane (CH ₄ , molecular weight 16.0426), ethane (C ₂ H ₆ , molecular weight 30.0694), propane ( C ₃ H ₈ , molecular weight 44.0962), low molecular hydrocarbon gas such as butane (C ₄ H ₁₀ , molecular weight 58.123) and the like are the main components. Among these, for example, when the gas to be collected is carbon monoxide (CO), the replacement gas to be used may be one having a molecular weight larger than that of carbon monoxide (CO).

The replacement gas used in the present embodiment is not particularly limited as long as it is a chemically inert gas. For example, nitrogen gas (N ₂ , molecular weight 28.0134) or helium gas (He, molecular weight 4) .0026), neon gas (Ne, molecular weight 20.179), argon gas (Ar, molecular weight 39.948), krypton gas (Kr, molecular weight 83.80), xenon gas (Xe, molecular weight 131.29), radon gas (Rn) And at least one selected from a group 0 rare gas such as a molecular weight 222), and the like may be selected according to the molecular weight of the gas to be collected. Among these, from the viewpoint of cost and the like, at least one of nitrogen gas and argon gas is preferable.

  When the gas to be collected is hydrogen, the replacement gas to be used may be an inert gas having a molecular weight greater than hydrogen, such as helium gas, argon gas, nitrogen gas, etc., and the gas to be collected is carbon monoxide. When the replacement gas is used, an inert gas having a molecular weight larger than that of carbon monoxide, such as argon gas or nitrogen gas, may be used. In addition, when a plurality of gases to be collected are hydrogen, carbon monoxide, carbon dioxide, methane, ethane, propane, and butane, the replacement gas to be used has a molecular weight larger than that of butane having the highest molecular weight among the gases. An active gas such as krypton gas, xenon gas, or radon gas may be used.

  In order to facilitate separation due to a mass difference between the replacement gas and the generated gas, it is preferable that the difference in molecular weight between the replacement gas and the generated gas is large. However, when the difference in molecular weight between the replacement gas and the generated gas is small, for example, in the case of nitrogen gas and carbon monoxide, separation by mass difference is possible by leaving the mixed gas for a long time.

  Moreover, in this embodiment, it is preferable to install the generated gas collector 16 at a position higher than the installation position of the secondary battery cell 10 and the installation position of the replacement gas circulation pipe 14 as the replacement gas circulation means. After supplying a predetermined amount of replacement gas into the replacement gas flow pipe 14, the valve 18 is closed, the valves 28 and 32 are opened, and the replacement gas is supplied in the replacement gas flow pipe 14 and the secondary battery cell 10 by the pump 24. By circulating the generated gas, the generated gas having a molecular weight smaller than that of the replacement gas is accumulated upward in the generated gas collector 16, so that the generated gas can be easily recovered. Further, since the generated gas having a molecular weight smaller than that of the replacement gas is accumulated and collected in the generated gas collector 16, the generated gas can be safely recovered without being released to the outside.

  Furthermore, the generated gas collector 16 is preferably detachable from the secondary battery device 1. As a result, when the generated gas collected in the generated gas collector 16 becomes close to the capacity of the generated gas collector 16, the generated gas collector 16 may be removed and replaced with the generated gas collector 16. . The generated gas collector 16 may be replaced periodically, and when a detector such as a gas sensor is installed in the generated gas collector 16 and it is detected that the amount of the generated gas collected exceeds a certain amount. A warning or the like may be issued and replaced. When the secondary battery device 1 is mounted on a vehicle or the like, the operation of the secondary battery device 1 can be controlled by a control device such as an ECU.

  Moreover, in this embodiment, as shown in FIG. 2, you may install generated gas collector 16A-16D in each secondary battery cell 10A-10D. In this case, a predetermined amount of replacement gas is supplied into the replacement gas flow pipe 14 and is circulated through the system as necessary, and then collected in the generated gas collectors 16A to 16D. Small generated gas can be easily recovered.

  Although there is no restriction | limiting in particular as a secondary battery in this embodiment, The lithium ion battery which uses lithium as electrolyte ion, a lithium polymer battery, a nickel hydride battery, a nickel cadmium battery, etc. are mentioned. Since the lithium ion battery may generate carbon monoxide gas or the like, it is preferable to use the generated gas collection method according to the present embodiment for the secondary battery constituted by the lithium ion battery.

  Examples of lithium ion batteries include carbon for the negative electrode, lithium transition metal oxide such as lithium cobaltate for the positive electrode, and an organic solvent such as ethylene carbonate and diethyl carbonate for the electrolyte and a lithium salt such as lithium hexafluorophosphate. There are no particular restrictions.

  By using the secondary battery generated gas collection method and the secondary battery device according to the present embodiment as described above, the generated gas inside the cell of the secondary battery during normal use or overdischarge is discharged. An increase in the internal pressure of the cell due to accumulation of the generated gas inside the cell can be suppressed. In particular, by using a replacement gas having a molecular weight larger than the gas to be collected in the generated gas, it is possible to prevent the generated gas from accumulating in the lower part inside the cell. The flow of the replacement gas into the system and the circulation of the replacement gas as necessary may be performed every time the secondary battery cell is stopped or periodically, and are not particularly limited. Further, the flow of the replacement gas into the system may be performed automatically, or may be performed as desired by the user.

  The secondary battery device according to the present embodiment can be used as, for example, a small power source for mobile devices such as a mobile phone and a portable personal computer, a power source for automobiles, a household power source, and the like. Further, the method for collecting generated gas of the secondary battery according to the present embodiment is applied to, for example, a secondary battery used as a small power source for mobile devices such as a mobile phone and a portable personal computer, a power source for automobiles, and a household power source can do.

It is the schematic which shows an example of the secondary battery apparatus which concerns on embodiment of this invention. It is the schematic which shows the other example of the secondary battery apparatus which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Secondary battery apparatus 10,10A, 10B, 10C, 10D Secondary battery cell, 12 Replacement gas supply cylinder, 14 Replacement gas distribution pipe, 16, 16A, 16B, 16C, 16D Generated gas collector, 18, 28 , 32 Valve, 20A, 20B, 20C, 20D Replacement gas inlet, 22A, 22B, 22C, 22D Replacement gas outlet, 24 pump, 26, 30 piping.

Claims (12)

A method of collecting generated gas of a secondary battery for collecting gas generated in a secondary battery,
A method for collecting a generated gas of a secondary battery, wherein the generated gas is discharged and collected from the inside of the secondary battery by circulating a replacement gas inside the secondary battery. A method for collecting generated gas of a secondary battery according to claim 1,
The method for collecting generated gas of a secondary battery, wherein the replacement gas has a molecular weight larger than that of the target gas in the generated gas. A method for collecting generated gas of a secondary battery according to claim 1 or 2,
The method for collecting generated gas of a secondary battery, wherein the replacement gas is at least one selected from nitrogen gas and rare gas. A method for collecting generated gas of a secondary battery according to any one of claims 1 to 3,
The method for collecting generated gas of a secondary battery, wherein the gas to be collected is at least one of hydrogen gas and carbon monoxide. A method for collecting generated gas of a secondary battery according to any one of claims 1 to 4,
The secondary battery is a lithium ion battery, and the method for collecting generated gas of the secondary battery. A secondary battery device for collecting gas generated in a secondary battery,
A replacement gas flow means for flowing a replacement gas inside the secondary battery and discharging the generated gas from the inside of the secondary battery;
Generated gas collecting means for collecting the generated gas;
A secondary battery device comprising: The secondary battery device according to claim 6,
The secondary battery device, wherein the generated gas collecting means is installed above an installation position of the replacement gas circulation means and the secondary battery. The secondary battery device according to claim 6 or 7,
The secondary battery device, wherein the generated gas collecting means is detachable. The secondary battery device according to any one of claims 6 to 8,
The secondary battery device, wherein the replacement gas has a molecular weight greater than that of the gas to be collected in the generated gas. The secondary battery device according to any one of claims 6 to 9,
The secondary battery device, wherein the replacement gas is at least one selected from nitrogen gas and rare gas. The secondary battery device according to any one of claims 6 to 10, wherein
The secondary battery device, wherein the gas to be collected is at least one of hydrogen gas and carbon monoxide. The secondary battery device according to any one of claims 6 to 11,
A secondary battery device, wherein the secondary battery is a lithium ion battery.

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