JP4501157B2 - Secondary battery pack - Google Patents

Description

  For example, the present invention relates to a secondary battery pack including a chargeable / dischargeable battery body such as a lithium ion battery.

Conventionally, lead-acid batteries are generally used as secondary batteries, but in recent years, lithium-ion batteries that have a very high power density and can be miniaturized have been widely used as power storage media. FIG. 5 shows a structure of a laminated lithium ion battery which is one form of the lithium ion battery. A lithium cell 1 as a laminated lithium ion battery is insulated between a positive electrode material 2 such as lithium cobaltate (LiCoO ₂ ) and lithium manganate (LiMnO ₂ ) and a negative electrode material 3 such as graphite (carbon). Therefore, after the separator 4 is inserted into a laminated structure 5 in which these layers are laminated, the laminated structure 5 is sealed with aluminum laminates 6 and 6 together with the electrolyte from above and below. The positive electrode material 2 and the negative electrode material 3 are formed with a positive electrode 2a and a negative electrode 3a, respectively, and project from the bonded portions of the aluminum laminates 6 and 6 to the outside. Incidentally, how extraction electrode, shape, Material and, like the size of the entire laminate battery is not particularly limited, there are various.

  Although the lithium cell 1 having such a structure has a very high power density as a power storage medium, it is vulnerable to overvoltage, and there is a risk of causing smoke and ignition when an excessive overvoltage is applied during charging.

  Hereinafter, the mechanism leading to smoke and ignition of the lithium cell 1 when overcharge is applied will be described with reference to FIG. 6 showing the state of the lithium cell 1 with respect to temperature.

First, when an overvoltage is applied, the decomposition of the electrolyte inside the battery is accelerated, heat is generated, and the battery temperature starts to rise. At the same time, an evaporation gas (diethyl carbonate, ethylene carbonate) of the electrolyte is generated inside the battery, causing the aluminum laminates 6 and 6 to expand. At this time, in the case where an explosion-proof valve is provided as an ejection part for specifying the ejection direction of the internal gas as disclosed in Patent Document 1, when the pressure in the battery rises above a predetermined value, this explosion-proof The gas inside the battery is discharged from the valve to the outside of the battery, and the explosion is prevented by venting. The separator 4 of this battery has a double structure, and is made of PE (polyethylene) and PP (polypropylene). When the internal temperature of the battery rises and reaches about 120 ° C., the internal separator 4 starts to contract. When the temperature further rises, the PE separator constituting the separator 4 melts at about 135 ° C. The other PP separator begins to melt at about 165 ° C. When the PP separator is melted, the internal dielectric breakdown of the lithium cell 1 proceeds. Also, broken sealing of aluminum laminate 6,6, internal gas starts to jet. When the temperature rises rapidly from there and thermal decomposition of the electrolyte occurs at about 250 ° C., gases such as CH ₄ , C ₂ H ₄ , C ₂ H ₆ are generated, and the insulating properties of the separator 4 are destroyed. Eventually, an internal short-circuit causes the spark phenomenon to become an ignition point, which eventually leads to ignition.

Thus, it has been known that the lithium cell 1 is weak against overvoltage because it is a lithium ion, and when the overvoltage is applied, it causes smoke and fire in the worst case. However, the detailed relationship between the amount of energy, including applied voltage and current, and the laminate-type lithium-ion battery until it smoked and ignited has not been elucidated, and there has been a situation where the fundamental measures cannot be taken. Therefore, as a provisional measure to solve this safety problem, a protection circuit (for example, Patent Document 2) for preventing battery smoke and ignition is usually installed in the charger or battery pack. . In Patent Document 1, when a combustible gas or the like is detected, the battery is prevented from being smoked and ignited by prohibiting charging of the secondary battery.
JP-A-11-283599 JP-A-8-222278

  However, if the protection circuit does not operate for some reason, the risk of smoke and fire is unavoidable, and the spread to the fields requiring high reliability such as power supply devices and uninterruptible power supply devices has been delayed.

  At present, in the mechanism leading to smoke and ignition as described above, it has not been elucidated how far the process proceeds with respect to injection energy (voltage / current stress) such as overvoltage and overcharge. Therefore, both battery manufacturers and device manufacturers that use batteries must rely on protection circuits against smoke and fire. However, the protection circuit that monitors and controls the battery has a fault when the monitoring unit (voltage monitor, current monitor, temperature monitor) is abnormal or the control unit (circuit unit) that receives and controls the signal from the monitoring unit is abnormal. In this case, or when a protection element (semiconductor switch such as a cut-off switch, a fuse, an FET, or a transistor) that operates in response to a signal from the control unit does not operate, it cannot function as a protection circuit. That is, in the worst case, there is a possibility of causing smoke and fire.

  In view of the above problems, an object of the present invention is to provide a secondary battery pack capable of preventing smoke and ignition of a secondary battery even when contents are ejected from the secondary battery.

In the secondary battery pack according to claim 1 of the present invention, a chargeable / dischargeable battery body, and a filter unit that is outside the battery body and adsorbs a combustible substance contained in the contents ejected from the battery body, An outer member provided with a discharge hole for covering the battery body and the filter part and discharging the content purified by passing through the filter part to the outside; and the battery body in pressure contact with the outer member And a heat radiating plate that transfers heat of the battery body to the outer member, and the filter part is a jet part that specifies the jet direction of the contents When the pressure in the battery body is increased, the contents immediately after being ejected are made to enter and pass through the filter part using the momentum that the contents are ejected from the ejection part. The That.

In this way, even if the contents are ejected from any part of the battery body due to an abnormality of the protection circuit, the contents are first retained in the outer member by the outer member covering the battery body, and leak to the outside of the secondary battery pack. I do not put out. And the combustible substance contained in the contents held in the outer member is surely adsorbed by the filter part, and only the contents not containing the combustible substance are discharged out of the outer member from the discharge hole provided in the outer member. Therefore, it is possible to prevent the flammable material from flowing out to the periphery of the secondary battery pack and to prevent smoke and ignition .

In addition, the heat sink radiates the heat of the battery body generated during charging and discharging, suppresses the temperature rise of the battery body, and the battery body tends to have a longer life if a certain amount of pressure is applied to its surface, By sandwiching the battery body with the heat radiating plate and press-contacting the heat radiating plate to the outer member, the battery body can be fixed in a state where an appropriate pressure is applied. Furthermore, by utilizing the momentum contents are ejected from the ejection unit, as it enters the filter unit and passed through quickly purify contents immediately after ejection, it can be made of non-flammable.

According to claim 1 of the present invention, electrostatic be content from which part ejection of Ikekarada, can be discharged from reliably the contents within the outer member to the outer member outside by removing combustible materials , with a simple configuration, it is possible to provide a secondary battery pack that can prevent fuming, ignition of the secondary battery.

Moreover, while suppressing the temperature rise of the battery body, it can be fixed in a state where an appropriate pressure is applied to the battery body. Further , the contents immediately after the ejection can be quickly purified to prevent smoke and ignition of the secondary battery. It is possible to provide a secondary battery pack that can be prevented.

  Hereinafter, preferred embodiments of the secondary battery pack according to the present invention will be described with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the same location as a prior art example, and since description of a common part overlaps, it abbreviate | omits as much as possible.

  FIG. 1 is a block diagram showing a schematic configuration when a lithium cell 1 as a chargeable / dischargeable battery body is installed in an electronic device or the like. In the figure, a lithium battery 1 and a protection circuit 11 are incorporated in a battery pack 10 as a secondary battery pack. The protection circuit 11 includes, for example, a current fuse, a temperature fuse, an overvoltage protection, and the like, and cuts off and protects the charging power supplied to the lithium cell 1 when overcurrent, overvoltage, or temperature is abnormal. A battery charger 12 for charging the lithium cell 1 by injecting charging power is connected to the front stage of the battery pack 10. The charger 12 includes a stabilized power source 13 that generates stabilized charging power, and a charging circuit 14 that charges the lithium cell 1 using the charging power. The charging circuit 14 includes a constant voltage / constant current circuit that linearly charges the lithium cell 1 with a constant charging voltage or charging current, a pulse charging circuit that pulse-charges the lithium cell 1 by supplying the charging current in pulses. These are appropriately determined depending on the performance and life of the battery.

  FIG. 2 is a perspective view showing the internal configuration of the battery pack 10, and FIGS. 3 and 4 are cross-sectional views of the main part of the configuration of the battery pack 20 as viewed from the vertical and horizontal directions. The battery pack 10 is mainly a print in which a battery stack 26 in which a plurality of lithium cells 1 are stacked and connected in a casing 20 as an outer member forming the outer shell, and a circuit component of the protection circuit 11 are mounted. A substrate 31 is accommodated. The casing 20 is formed of a member having excellent heat dissipation, such as an aluminum material, in a box shape, and its internal space is partitioned into a battery chamber 22 and a substrate chamber 23 by a partition plate 21 formed substantially at the center. . A battery stack 26 is accommodated in the battery chamber 22, and a printed circuit board 31 is separately accommodated in the substrate chamber 23.

  The battery stack 26 has a configuration in which a plurality of lithium cells 1 are stacked one above the other, and an interlayer member 28 such as an aluminum plate that is excellent in heat dissipation is inserted between the lithium cells 1. The battery stack 26 tends to generate heat at the center thereof, and the lithium cell 1 located at the center tends to be hotter than the others. By providing the interlayer member 28 having excellent heat dissipation between the lithium cells 1, the heat of each lithium cell 1 is quickly dissipated, so that the heat does not flow in the center of the battery stack 26, and the temperature of the lithium cell 1 The rise can be suppressed. Since the lithium cell 1 constituting the battery stack 26 has a tendency that the contact between the electrode and the electrolyte solution becomes better and the life is extended when a certain amount of pressure is applied to the surface thereof. When the heat sinks 30 and 30 are pressed against the casing 20 by being sandwiched by 30, the battery stack 26 is fixed in an appropriate pressure state and is accommodated in the battery chamber 22. Further, the heat sinks 30, 30 transmit the heat of the battery stack 26 generated during charging / discharging to the casing 20 to dissipate the heat, and suppress the temperature rise of each lithium cell 1. The lithium cell 1 of this embodiment is provided with an explosion-proof valve 27 at the opposite end where the positive electrode 2a and the negative electrode 3a are provided. The positive electrode 2 a and the negative electrode 3 a of the lithium cell 1 and the battery stack 26 are electrically connected to the protection circuit 11 mounted on the printed circuit board 31 by a connection cable 33 that penetrates the partition plate 21.

  In addition to the battery stack 26, the battery chamber 22 accommodates a filter unit 25 in the vicinity of the explosion-proof valve 27 of the lithium cell 1. The filter unit 25 is made of, for example, activated carbon and an adsorbing member corresponding thereto, a nanofiber filter fiber material capable of adsorbing a volatile organic solvent, etc. Inflammable materials such as fumes, volatile organic gases, and the like are absorbed. A gas vent hole 32 as an exhaust hole is formed in the wall surface of the battery chamber 22 facing the filter portion 25.

  The printed circuit board 31 accommodated in the substrate chamber 23 is fixed to the casing 20 by, for example, screwing. The printed circuit board 31 is mounted with a heat generating component 35 such as a MOSFET constituting the protection circuit 11, and the heat generating component 35 is thermally applied to the heat sink 36 that forms the side wall of the substrate chamber 23 in the longitudinal direction of the casing 20. It is connected to the. Although the heat sink 36 is formed of a thick flat plate member in the drawing, a plurality of fins and the like may be arranged in parallel to increase the heat dissipation capability. When the battery stack 26 is charged and discharged, the heat generating component 35 generates heat, so that the heat is radiated by the heat sink 36. An opening for exposing the main connector 41 and the alarm connector 40 is formed in the wall surface of the substrate chamber 23 which is orthogonal to the heat sink 36 and is in the short direction of the casing 20. The main connector 41 is electrically connected to the protection circuit 11 by being mounted on the printed circuit board 31 by, for example, soldering, and the battery stack 26 is connected to the main connector 41 by connecting the charger 12 (not shown). Charging power for charging can be supplied to the battery pack 10. The alarm connector 40 is provided for taking out an alarm signal output from the protection circuit 11 to the outside, for example, when charging power is interrupted by overvoltage / overcharge protection.

  Next, the operation of the battery pack 10 during overvoltage / overcharge will be described.

When an overvoltage is applied from the charger 12 to the battery pack 10, decomposition of the electrolyte in the lithium cell 1 is accelerated, heat is generated, and the temperature of the lithium cell 1 starts to rise. At the same time, an evaporation gas of the electrolytic solution is generated inside the lithium cell 1 to cause the aluminum laminates 6 and 6 to expand. When the temperature rises further and thermal decomposition of the electrolyte occurs, volatile organic gases such as CH ₄ , C ₂ H ₄ , and C ₂ H ₆ are generated. At this time, when the pressure in the lithium cell 1 rises to a predetermined value or more, an internal gas such as an evaporation gas or a volatile organic gas of the electrolyte in the lithium cell 1 is ejected from the explosion-proof valve 27. That there is no explosion-proof valve 27 or, if there is an abnormality such as explosion-proof valve 27 is clogged, the broken sealing of aluminum laminate 6,6 lithium cell 1, the internal gas is ejected therefrom. The internal space of the casing 20 that covers the battery stack 26 is partitioned into a battery chamber 22 and a substrate chamber 23 by a partition plate 21, and both are isolated in an airtight state. Internal gas does not flow into the substrate chamber 23, and ignition from the protection circuit 11 mounted on the printed circuit board 31 and adverse effects on the components mounted on the printed circuit board 31 can be prevented. In this way, by accommodating the battery stack 26 in the battery chamber 22 formed in the casing 20, no matter what part of the lithium cell 1 is blown out due to an abnormality of the protection circuit 11, the lithium cell 1 is first extracted. The covering casing 20 keeps the internal gas in the battery chamber 22 and thus in the casing 20, and does not leak out of the substrate chamber 23 or the battery pack 10.

  The internal gas ejected from the lithium cell 1 enters the filter unit 25 provided in the vicinity of the explosion-proof valve 27, where it is purified by adsorbing the combustible substance contained in the internal gas, and the combustible gas concentration Decreases and becomes nonflammable gas by the time it exits the filter unit 25. In the present embodiment, the filter unit 25 is provided facing and close to the explosion-proof valve 27 so as to be positioned in the direction in which the internal gas is ejected. Therefore, using the momentum of the internal gas expelled from the explosion-proof valve 27, it is allowed to enter and pass through the filter unit 25 as it is, to quickly purify the internal gas immediately after the ejection, and to make a noncombustible gas containing no flammable substances. be able to. The internal gas purified by passing through the filter unit 25 is finally discharged from the gas vent hole 32 to the outside of the casing 20, so that the internal pressure of the casing 20 does not rise abnormally. When the purified object that has passed through the filter unit 25 is a liquid, the gas vent hole 32 may be provided below or on the bottom surface and drained from the gas vent hole 32. Thus, by providing the filter part 25 in the battery pack 10, the combustible substance contained in the internal gas ejected from the lithium cell 1 is absorbed, so that the combustible substance is prevented from leaking outside the casing 20. can do.

  As described above, in the battery pack 10 of this embodiment, the lithium cell 1 as a chargeable / dischargeable battery body and the internal gas as the contents ejected from the lithium cell 1 outside the lithium cell 1 are included. And a filter unit 25 that adsorbs the combustible material.

  In this way, even if the internal gas is ejected from the lithium cell 1 due to an abnormality of the protection circuit 11, the flammable substance contained in the internal gas is adsorbed by the filter unit 25, Prevents flammable substances from flowing out and prevents smoke and ignition. Therefore, it is possible to provide a battery pack 10 that can prevent smoke and fire of the lithium cell 1 and thus the battery stack 26 with a simple configuration even when internal gas is ejected from the lithium cell 1.

Further, in the battery pack 10 of the present embodiment, a chargeable / dischargeable lithium cell 1 and a filter unit 25 that is outside the lithium cell 1 and adsorbs a combustible substance contained in an internal gas ejected from the lithium cell 1; A casing 20 as an outer member, which covers the lithium cell 1 and the filter portion 25 and is provided with a gas vent hole 32 as a discharge hole for discharging the internal gas purified by passing through the filter portion 25 to the outside ; The lithium cell 1 is sandwiched in pressure contact with 20 and fixed in a state where pressure is applied to the lithium cell 1, and the heat sinks 30 and 30 for transferring the heat of the lithium cell 1 to the casing 20 are provided . When the pressure in the lithium cell 1 rises, the internal gas is provided in the vicinity of the explosion-proof valve 27 as a jetting part for specifying the jetting direction of the internal gas jetted from the lithium cell 1. Using the momentum ejected from the explosion-proof valve 27, enters the interior gas immediately after ejection to the filter unit 25 has a configuration to pass.

In this way, even if the internal gas is ejected from any part of the lithium cell 1 due to an abnormality of the protection circuit 11 or the like, the internal gas is first retained in the casing 20 by the casing 20 covering the lithium cell 1, and the battery pack 10 outside. There is no leakage. Then, the combustible material contained in the internal gas retained in the casing 20 is reliably adsorbed by the filter unit 25, and the non-combustible material is an internal gas that does not contain the combustible material from the vent hole 32 provided in the casing 20. Since only the characteristic gas is discharged to the outside of the casing 20, the outflow of the combustible substance around the battery pack 10 can be prevented, and smoke and ignition can be prevented. As described above, any part of the lithium cell 1 from which the internal gas is ejected can surely remove the combustible material from the internal gas in the casing 20 and discharge it to the outside of the casing 20. It is possible to provide the battery pack 10 capable of preventing smoke and ignition of the lithium cell 1 and the battery stack 26 .

Further, the heat sinks 30 and 30 dissipate the heat of the lithium cell 1 generated during charging and discharging to suppress the temperature rise of the lithium cell 1, and the life of the lithium cell 1 when a certain amount of pressure is applied to the surface thereof. Since there is a tendency to extend, the lithium cell 1 is sandwiched between the heat radiating plates 30 and 30, and the heat radiating plates 30 and 30 are pressed against the casing 20, so that the lithium cell 1 can be fixed in an appropriate pressure state. Furthermore, by using the momentum at which the internal gas is ejected from the explosion-proof valve 27, it is allowed to enter and pass through the filter unit 25 as it is, and the internal gas immediately after the ejection can be quickly purified to become nonflammable gas. Therefore, it is possible to provide a battery pack 10 that can quickly purify the internal gas immediately after jetting and prevent smoke and ignition of the lithium cell 1 and thus the battery stack 26 in advance.

  In addition, this invention is not limited to the said Example, It can change in the range which does not deviate from the meaning of this invention. The secondary battery to which the present invention can be applied is not limited to a lithium ion battery, and may be any battery as long as the contents such as internal gas are ejected at the time of overvoltage / overcharge. If the liquid content is ejected at a high temperature of the secondary battery, the filter portion may be configured as a sponge-like liquid absorbing member, for example, so as to suck out the liquid content and prevent outflow. Further, the filter unit 25 may be arranged so as to surround the lithium cell 1 and thus the battery stack 26, or the filter unit 25 may be directly attached to the lithium cell 1.

It is a block diagram which shows the structure of the secondary battery pack in 1st Example of this invention. It is a perspective view which shows the structure of a secondary battery pack same as the above. It is a principal part cross-sectional view which shows the structure of a secondary battery pack same as the above. It is a principal part horizontal longitudinal view which shows the structure of a secondary battery pack same as the above. It is a disassembled perspective view which shows the internal structure of a laminate type lithium ion battery. It is explanatory drawing which shows the mechanism leading to the smoke generation and ignition of a laminate type lithium ion battery.

1 Lithium cell (battery body)
10 Battery pack (secondary battery pack)
20 Casing (outer member)
25 Filter section
27 Explosion-proof valve (spout part)
30 Heat sink
32 Gas vent hole (exhaust hole)

Claims (1)

A chargeable / dischargeable battery body; a filter section outside the battery body for adsorbing a combustible substance contained in the contents ejected from the battery body; and covering the battery body and the filter section; An outer member provided with a discharge hole for discharging the contents purified by passing through the section to the outside, and sandwiching the battery body in pressure contact with the outer member, in a state where pressure is applied to the battery body A heat radiating plate for fixing and transmitting heat of the battery body to the outer member, the filter portion being provided in the vicinity of a jetting portion for specifying a jetting direction of the contents, and pressure in the battery body The secondary battery pack is configured to allow the content immediately after being ejected to enter and pass through the filter portion by utilizing the momentum that the content is ejected from the ejecting portion when the temperature rises .

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