JP2006260777A - Mounting structure of secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting structure of a secondary battery securing a protective function even in case contents blow out from it and preventing smoking and firing. <P>SOLUTION: The inside of a casing 20 is partitioned into a battery compartment 22 and a substrate compartment 23, of which, the former 22 contains a battery stack consisting of a plurality of lithium cells 1, and the later 23 contains a printed board 31 mounting a protective circuit 11. Even if overvoltage is impressed from a charger 12 on a battery pack 10, and inner gas inside the lithium cells blows through an explosion-proof valve 27, the inner gas will not flow into the substrate compartment 23 since the casing 20 is separated into the battery compartment 22 and the substrate compartment, so that flashing from the protective circuit 11 is prevented, and then, protection from overcharging, overvoltage or the like of the lithium cells by the protective circuit 11 is continued. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  For example, the present invention relates to a mounting structure for a secondary battery when a chargeable / dischargeable secondary battery such as a lithium ion battery is actually installed.

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. There are no particular restrictions on how to take out the electrode, the shape, the material, the size of the entire laminated battery, etc., and there are various types.

Although the lithium cell 1 having such a structure has a very high power density as a power storage medium, it uses a material that generates a flammable gas at a high temperature, and therefore emits smoke when some abnormality occurs in the battery. There is a risk of ignition. Examples of the flammable internal gas generated in the lithium cell 1 include electrolyte evaporation gas (diethyl carbonate, ethylene carbonate), CH ₄ , C ₂ H ₄ , and C ₂ H ₆ generated from the separator 4. In addition, when the lithium cell 1 is at a high temperature, these internal gases are 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 to a predetermined value or more, this explosion-proof The internal gas in the battery is released from the valve to the outside of the battery and vented to prevent explosion.

Thus, in the lithium cell 1, combustible internal gas is generated at a high temperature, and in the worst case, there is a risk of causing smoke and ignition. Therefore, as a measure for solving this safety problem, a protection circuit (for example, Patent Document 2) for preventing battery smoke and ignition is usually installed in the 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. Generally, when the lithium cell 1 is actually installed in a battery pack, the protection circuit is mounted on the top of a battery stack formed by stacking a plurality of lithium cells 1 up and down.
JP-A-11-283599 JP-A-8-222278

  However, even if the protective circuit is provided, if a flammable internal gas is generated inside the lithium cell 1 for some reason and is ejected to the outside, anxiety that the risk of smoke and ignition is inevitable is eliminated. It was not reached. If the internal gas is ejected from the lithium cell 1 and reaches the protection circuit mounted on the lithium cell 1, there is a possibility that the combustible internal gas may be ignited due to a spark phenomenon due to a short circuit of the protection circuit. Moreover, when the high-temperature internal gas adversely affects the protection circuit, the overvoltage / overcharge protection may not function, and the lithium cell 1 may be smoked or ignited.

  Accordingly, in view of the above problems, the present invention provides a secondary battery protection function that ensures a secondary battery protection function even when contents are ejected from the secondary battery, and prevents secondary battery smoke and fire. An object is to provide a mounting structure.

  In the secondary battery mounting structure according to claim 1 of the present invention, a chargeable / dischargeable secondary battery, a control unit for protecting the secondary battery, and an isolating means for isolating the secondary battery and the control unit. It has.

  If it does in this way, since a control part is isolated from a secondary battery by the isolation | separation means, the arrival to a control part can be prevented with respect to the content which ejected from the secondary battery. That is, since the mutual influence between the combustible contents and the control unit is cut off, it is possible to prevent ignition from the control unit and to continue protection of the secondary battery by the control unit even when the secondary battery is abnormal.

  In the secondary battery mounting structure according to the second aspect of the present invention, the isolation means is an outer member in which a battery chamber that houses the secondary battery and a control chamber that houses the control unit are formed.

  In this case, by providing the battery chamber and the control chamber in the outer member, the secondary battery and the control unit are accommodated in a completely isolated state, so that the contents from the secondary battery in the battery chamber Even if an object is ejected, the contents do not reach the control unit accommodated in the control room. That is, since the mutual influence between the flammable contents and the control unit is cut off, it is possible to prevent ignition from the control unit and to continue protection of the secondary battery by the control unit even when the secondary battery is abnormal.

  In the secondary battery mounting structure according to the third aspect of the present invention, there is provided a collection unit for collecting the contents ejected from the secondary battery.

  In this way, since the contents ejected from the secondary battery can be collected in the recovery unit, it is possible to prevent outflow to the periphery of the secondary battery.

  In the secondary battery mounting structure according to a fourth aspect of the present invention, the recovery part is provided in the vicinity of the ejection part that specifies the ejection direction of the contents.

  If it does in this way, using the momentum which a content spouts from a spout part, it will enter into a recovery part as it is, and the contents immediately after spout can be collected quickly.

  According to the first aspect of the present invention, the secondary battery is mounted so as to ensure the protection function of the secondary battery even when the contents are ejected from the secondary battery, and to prevent the secondary battery from being smoked or ignited. Structure can be provided.

  According to the second aspect of the present invention, the secondary battery and the control unit can be completely separated, and even when the contents are ejected from the secondary battery, the secondary battery is reliably protected and the secondary battery is protected. It is possible to provide a secondary battery mounting structure that can prevent the occurrence of smoke and ignition.

  According to the third aspect of the present invention, it is possible to prevent the contents ejected from the secondary battery from flowing out to the periphery of the secondary battery and to minimize the influence on the surroundings.

  According to claim 4 of the present invention, the contents immediately after the ejection can be quickly collected, the outflow to the periphery of the secondary battery can be prevented, and the influence on the surroundings can be minimized.

  Hereinafter, preferred embodiments of a secondary battery mounting structure 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 secondary battery 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 10 as viewed from the vertical and horizontal directions. The battery pack 10 is mainly a printed circuit board 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 circuit components of the protection circuit 11 are mounted. 31 is configured. 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 divided into a battery chamber 22 and a substrate chamber 23 by a partition plate 21 as a separating means formed substantially in the center. It is partitioned. 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 the battery chamber 22, a gas storage unit 25 as a recovery unit is provided near the explosion-proof valve 27 of the battery stack 26. The gas accumulating unit 25 is used for the internal gas as the contents ejected from the explosion-proof valve 27 when the lithium cell 1 is overcharged, that is, the internal gas such as smoke, the evaporation gas of the electrolyte solution directly connected to the ignition, or the volatile organic gas It is provided to collect combustible substances contained in one place. A gas vent hole 32 serving as a discharge hole is formed in the wall surface of the battery chamber 22 that becomes one wall surface of the gas storage unit 25 and faces the explosion-proof valve 27. In addition, L-shaped wall bodies 24 and 24 made of a member having good thermal conductivity such as aluminum are attached to the gas storage unit 25 on the partition plate 21 and the wall surface of the battery chamber 22 facing the partition plate 21, respectively. The wall bodies 24, 24 protrude inward from the both side walls of the battery chamber 22 and are positioned so as to overlap each other at a certain distance in the middle of the battery chamber 22, which is the position facing the explosion-proof valve 27. Yes. The two walls 24 and 24 form a flow path 29 that meanders from one end of the battery stack 26 provided with the explosion-proof valve 27 toward the wall surface of the battery chamber 22 in which the gas vent holes 32 are formed.

  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. When there is an abnormality such as the one without the explosion-proof valve 27 or the explosion-proof valve 27 being clogged, the sealing of the aluminum laminates 6 and 6 of the lithium cell 1 is broken, and 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, and therefore, from the battery chamber 22 in which the battery stack 26 is accommodated. 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 protection circuit 11 can be prevented. That is, since the mutual influence between the flammable internal gas and the protection circuit 11 is cut off, the ignition from the protection circuit 11 is prevented, and overcharge / overvoltage of the lithium cell 1 by the protection circuit 11 even when the lithium cell 1 is abnormal. Protection can continue. 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 is collected in one place by the gas accumulation part 25 provided in the vicinity of the explosion-proof valve 27. First, the internal gas ejected from the explosion-proof valve 27 collides with the wall body 24 of the gas accumulation unit 25 provided to face the explosion-proof valve 27. Since the wall body 24 is thermally connected to the casing 20 and is in a state where the temperature is significantly lower than that of the internal gas, the internal gas condenses on the surface of the wall body 24 and becomes liquid. In the present embodiment, the wall body 24 of the gas accumulating portion 25 is provided so as to face 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 ejected from the explosion-proof valve 27, the gas can enter the flow path 29 as it is, and the internal gas immediately after the ejection can be quickly recovered. Thereafter, the internal gas flows through the flow path 29, but the flow path 29 meanders so as to increase its surface area, so that the wall bodies 24 and 24 and the wall surfaces of the gas storage section 25 are flown through the flow path 29. The internal gas containing the combustible substance gradually condenses on the casing 20 that forms the gas, and the combustible gas concentration in the gas storage unit 25 decreases. Then, the internal gas flowing through the flow path 29 is finally discharged from the gas vent hole 32 to the outside of the casing 20. Since the exhaust gas has a sufficiently low combustible gas concentration, it does not affect the periphery of the battery pack 10 and the internal pressure of the casing 20 does not rise abnormally. The liquid internal gas accumulated in the gas accumulation unit 25 is taken out from the gas accumulation unit 25 later and subjected to appropriate processing. If the flow path 29 is formed to be inclined toward the gas vent hole 32, it can be easily collected near the gas vent hole 32 if the viscosity of the liquefied internal gas is low. In this case, the gas vent hole 32 may be provided below or on the bottom surface to drain the liquid from the gas vent hole 32.

  As described above, in the secondary battery mounting structure of the present embodiment, the lithium cell 1 (battery stack 26) as a chargeable / dischargeable secondary battery, and the protection circuit 11 as a control unit for protecting the lithium cell 1, A partition plate 21 is provided as an isolation means for isolating the lithium cell 1 and the protection circuit 11.

  In this way, since the protection circuit 11 is isolated from the lithium cell 1 by the partition plate 21, it is possible to prevent the internal gas as the contents ejected from the lithium cell 1 from reaching the protection circuit 11. That is, the mutual influence between the combustible internal gas and the protection circuit 11 is cut off, so that the ignition from the protection circuit 11 is prevented and the protection of the lithium cell 1 by the protection circuit 11 is continued even when the lithium cell 1 is abnormal. Can do. As described above, it is possible to provide a secondary battery mounting structure that can secure the protection function of the lithium cell 1 even when internal gas is ejected from the lithium cell 1 and can prevent the smoke and ignition of the lithium cell 1 in advance. it can.

  Further, in the secondary battery mounting structure of the present embodiment, the isolation means is an outer member in which a battery chamber 22 that houses the lithium cell 1 and a substrate chamber 23 that serves as a control chamber that houses the protection circuit 11 are formed. Casing 20.

  In this case, by providing the battery chamber 22 and the substrate chamber 23 in the casing 20, the lithium cell 1 and the protection circuit 11 are accommodated in separate rooms in a completely isolated state. Even if the internal gas is ejected from the lithium cell 1, the internal gas does not reach the protection circuit 11 accommodated in the substrate chamber 23. That is, the mutual influence between the combustible internal gas and the protection circuit 11 is cut off, so that the ignition from the protection circuit 11 is prevented and the protection of the lithium cell 1 by the protection circuit 11 is continued even when the lithium cell 1 is abnormal. Can do. As described above, the lithium cell 1 and the protection circuit 11 can be completely isolated, and even when the internal gas is ejected from the lithium cell 1, the protection function of the lithium cell 1 is ensured, and the smoke and ignition of the lithium cell 1 are ensured. It is possible to provide a secondary battery mounting structure that can be prevented in advance.

  Furthermore, in the secondary battery mounting structure of the present embodiment, a gas storage unit 25 is provided as a recovery unit for collecting the internal gas ejected from the lithium cell 1.

  In this way, since the internal gas ejected from the lithium cell 1 can be collected in the gas storage unit 25, the outflow to the periphery of the lithium cell 1 can be prevented. Accordingly, it is possible to prevent the internal gas ejected from the lithium cell 1 from flowing out to the periphery of the lithium cell 1 and to minimize the influence on the surroundings.

  Further, in the secondary battery mounting structure of the present embodiment, the gas accumulating portion 25 is provided in the vicinity of the explosion-proof valve 27 as an ejection portion for specifying the ejection direction of the internal gas.

  In this way, the internal gas immediately after the jetting can be quickly collected by using the momentum of the jetting of the internal gas from the explosion-proof valve 27 and entering the gas accumulating unit 25 as it is. Therefore, the internal gas immediately after ejection can be quickly recovered, the outflow to the periphery of the lithium cell 1 can be prevented, and the influence on the environment can be minimized.

  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. Further, the protection circuit 11 may not be accommodated in the casing 20 as long as it can be isolated from the lithium cell 1. Further, in order to increase the amount of condensation in the gas storage unit 25, a plurality of fins may be arranged in parallel in the flow path 29 to improve the cooling performance, and various things such as air cooling and water cooling by a cooling fan may be used. Can be considered.

It is a block diagram which shows the structure of the mounting structure of the secondary battery in 1st Example of this invention. It is a perspective view which shows the structure of the mounting structure of a secondary battery same as the above. It is a principal part cross-sectional view which shows the structure of the mounting structure of a secondary battery same as the above. It is a principal part horizontal longitudinal view which shows the structure of the mounting structure of a secondary battery same as the above. It is a disassembled perspective view which shows the internal structure of a laminate type lithium ion battery.

Explanation of symbols

1 Lithium cell (secondary battery)
11 Protection circuit (control unit)
20 Casing (outer member)
21 Partition plate (isolation means)
22 Battery compartment
23 Board room (control room)
25 Gas storage unit (recovery unit)
27 Explosion-proof valve (spout part)

Claims (4)

A secondary battery mounting structure comprising: a chargeable / dischargeable secondary battery; a control unit that protects the secondary battery; and an isolation unit that isolates the secondary battery and the control unit. 2. The mounting structure for a secondary battery according to claim 1, wherein the isolation means is an outer member in which a battery chamber that houses the secondary battery and a control chamber that houses the control unit are formed. The mounting structure for a secondary battery according to claim 1, further comprising a collection unit that collects contents ejected from the secondary battery. The mounting structure for a secondary battery according to claim 3, wherein the recovery unit is provided in the vicinity of a jetting part that specifies a jetting direction of the contents.

Images