WO2012014398A1

WO2012014398A1 - Battery module and battery pack using same

Info

Publication number: WO2012014398A1
Application number: PCT/JP2011/004005
Authority: WO
Inventors: 安井　俊介; 中嶋　琢也; 裕史高崎; 下司　真也; 永山　雅敏
Original assignee: パナソニック株式会社
Priority date: 2010-07-30
Filing date: 2011-07-13
Publication date: 2012-02-02
Also published as: JP2013214354A

Abstract

Disclosed is a battery module in which a plurality of batteries are arranged and stored inside a housing. Each battery, in an electrode part thereof, has an open part through which a gas generated inside said battery is discharged outside the battery. A separating plate provided in contact with the cases of the batteries, around the electrode parts of the batteries, partitions the housing into: a storage section which stores the plurality of batteries and a cooling fluid or cooling agent which fills the gaps between the plurality of batteries; and a discharge chamber through which the gas discharged from the open parts in the electrode parts is discharged outside the housing. The open parts in the electrode parts connect to the discharge chamber via through-holes formed in the separating plate. This configuration allows a parallel connection and, while keeping the temperatures of the plurality of batteries uniform, allows efficient temperature regulation with respect to heat generation due to factors such as the batteries being short-circuited.

Description

Battery module and battery pack using the same

The present invention relates to a battery module including a plurality of batteries that does not affect other batteries even if a problem such as heat generation occurs in the battery, and a battery pack using the same.

In recent years, demand for rechargeable secondary batteries such as nickel metal hydride, nickel cadmium, and lithium ion is increasing from the viewpoint of resource saving and energy saving. Among these, lithium ion secondary batteries are characterized by high electromotive force and high energy density while being lightweight. For this reason, there is an increasing demand for power sources for driving various types of portable electronic devices such as mobile phones, digital cameras, video cameras, laptop computers, and mobile communication devices.

On the other hand, in order to reduce the amount of fossil fuel used and the amount of CO ₂ emission, there is an increasing expectation for a battery pack as a power source for driving a motor of an automobile or the like. This battery pack is configured by mounting a plurality of battery modules including one or more batteries in order to obtain a desired voltage and capacity.

In the development of the above battery module, a battery module that stores a predetermined power in a limited space such as an automobile is housed, so that downsizing of the battery module has become a big issue.

Therefore, in an assembled battery (battery module) composed of a plurality of batteries, a configuration is disclosed in which wiring for detecting connection between each battery and voltage or temperature is connected by a pattern wiring formed on a printed circuit board (for example, a patent). Reference 1). Similarly, a power supply device (battery pack) in which a plurality of power supply modules are housed in a holder case and connected via an end plate is disclosed (for example, see Patent Document 2). By providing sensor leads and power leads for connecting the power supply modules to the end plate, it is possible to reduce connection defects and reduce the size.

Also, as the capacity of the battery stored in the battery module increases, the battery itself may generate heat and become high temperature depending on the form of use. Therefore, not only the safety of the battery itself but also the safety of the battery module in which they are assembled is more important. In other words, the battery causes an increase in internal pressure due to gas generated by overcharge, overdischarge, internal short circuit or external short circuit, and in some cases, the battery outer case may burst. Therefore, in general, the battery is provided with a vent mechanism for venting gas, a safety valve, and the like to release the internal gas. At this time, smoke may be generated due to ignition of the exhausted gas, and there are problems in reliability and safety.

Therefore, by storing a plurality of batteries in the battery chamber in the case and providing an opening in the partition wall facing the safety valve of each battery, the gas injected from the battery in an abnormal state is discharged from the discharge port through the exhaust chamber. A power supply device (battery module) configured to be discharged is disclosed (for example, see Patent Document 3).

JP 2000-208118 A JP 2000-223166 A JP 2007-27011 A

However, in the battery modules shown in Patent Document 1 and Patent Document 2, if one battery abnormally generates heat and the safety valve is activated, the amount of heat of the generated battery or the influence on surrounding batteries due to ignition of the gas to be ejected is affected. There is a problem that each battery deteriorates in a chained manner. That is, in a battery module equipped with a plurality of batteries, there is a problem of how to suppress the influence of an abnormal battery to the minimum by suppressing expansion to surrounding batteries.

In addition, the battery module shown in Patent Document 3 is provided with an opening on the partition wall of the case so as to face the safety valve of the battery, and the ejected gas is discharged outside without filling the battery chamber. However, although a circuit board built in a resin is disclosed, there is no disclosure or suggestion of a connection method with a battery or the like. Therefore, when the surface of the battery on the side of the safety valve is connected with the connection terminal, it is unclear how to maintain the airtightness with the partition wall. In addition, it is difficult to align the safety valve of the battery and the open portion of the partition wall, and there is a problem that if the positioning is performed by the recess, a space is generated between the batteries and the size cannot be reduced. Further, since the battery and the circuit board are fixed and built in with resin, there is a problem in miniaturization of the battery module.

In order to solve such a problem, the applicant of the present application has disclosed a configuration of a battery module capable of minimizing the influence on the surrounding battery due to abnormal heat generation of the defective battery, as disclosed in Japanese Patent Application No. 2010-550963 (PCT). / JP2010 / 004485).

22 (a) and 22 (b) are diagrams showing the configuration of the battery module 1000 disclosed in the above application specification. The battery 1040 has the gas generated inside the battery at the electrode portion 1016 of the battery 1040 outside the battery. The housing 1050 has a discharge portion 1017 for discharging, and a housing portion 1054 that houses a plurality of batteries 1040 by a wiring substrate 1030 disposed in contact with a battery case 1005 around the electrode portion of the battery 1040, and an electrode And an exhaust chamber 1024 for exhausting the gas exhausted from the open portion 1017 to the outside of the housing 1050. The electrode portion 1016 of the battery 1040 is connected to the connection body 1032 formed on the wiring substrate 1030, and the open portion 1017 of the electrode portion 1016 is connected to the exhaust chamber 1024 through the through hole 1036 formed in the wiring substrate 1030. Communicate.

With such a configuration, the wiring substrate 1030 is brought into contact with the battery case 1005 around the electrode portion 1016 of the battery 1040, and the open portion 1017 of the electrode portion 1016 is exhausted through the through hole 1036 formed in the wiring substrate 1030. By communicating with the chamber 1024, the discharge space of the gas ejected by opening the vent mechanism of the battery 1040 can be limited within the through hole 1036. Therefore, the gas discharged from the open portion 1017 of the electrode portion 1016 is discharged to the exhaust chamber 1024 through the through-hole 1036 and further to the outside of the housing 1050, so that the gas to the adjacent battery 1040 is discharged. Can be prevented from entering. Further, the wiring board 1030 can significantly reduce the space required for routing power supply wiring and control wiring. As a result, a battery module 1000 that is as thin and small as the battery 1040 and that is highly safe and highly reliable can be realized.

By the way, in the battery module using a large number of batteries, it is necessary to minimize the influence on the surrounding battery due to abnormal heat generation of the defective battery, and in addition to the high capacity and high output of the battery module. As a result, the heat generated by charging / discharging increases, and it is necessary to cool each battery efficiently in order to drive the battery module safely.

The present invention has been made in view of such a problem, and the main object of the present invention is to minimize the influence on the surrounding batteries due to abnormal heat generation of the defective battery, and to efficiently remove a plurality of batteries. It is an object of the present invention to provide a small and thin battery module that can be cooled.

The battery module of the present invention is a battery module in which a plurality of batteries are arranged and housed in a housing, and the battery has an open portion that discharges gas generated in the battery to the outside of the battery at the electrode portion of the battery. The housing has a housing part that accommodates a plurality of batteries and a gas that is discharged from the open part of the electrode part by a separation plate disposed in contact with the battery case around the electrode part of the battery. And an exhaust chamber that exhausts the air to the outside of the housing. The storage portion stores a coolant filled in the gaps of the plurality of batteries, and the open portion of the electrode portion is formed on the separation plate. The structure which is connected to the exhaust chamber through the through-hole.

In a preferred embodiment, the separation plate is made of a wiring board, and the electrode portion of the battery is connected to a connection body formed on the wiring board.

In the battery pack of the present invention, a plurality of the battery modules are connected in series and / or in parallel. Thereby, according to a use, the battery pack provided with arbitrary voltages and capacity | capacitance is realizable.

In the battery module of the present invention, it is possible to minimize the influence on the surrounding batteries due to abnormal heat generation of the defective battery, and it is possible to efficiently cool a plurality of batteries. As a result, a small and thin battery module that is safe and stable can be realized.

It is sectional drawing of the battery which comprises the battery module in the 1st Embodiment of this invention. (A) is a perspective view of the battery module according to the first embodiment of the present invention, (b) is a cross-sectional view taken along line 2B-2B of (a), and (c) is an enlarged cross section of 2C part of (b). FIG. It is a disassembled perspective view of the battery module in the 1st Embodiment of this invention. (A) is sectional drawing of the battery module in 1st Embodiment, (b) is an expanded sectional view of the 4B section of (a). It is the disassembled perspective view which showed the other structure of the battery module in 1st Embodiment. It is the perspective view which showed the other structure of the cover body in 1st Embodiment. It is the disassembled perspective view which showed the other structure of the housing | casing in 1st Embodiment. It is the disassembled perspective view which showed the other structure of the housing | casing in 1st Embodiment. It is the elements on larger scale which showed other composition of the wiring board in a 1st embodiment. It is sectional drawing of the battery which comprises the battery module in the modification of 1st Embodiment. (A) is a perspective view of a battery module in a modification of the first embodiment, (b) is a cross-sectional view taken along the line 11B-11B in (a), and (c) is an enlarged cross section of a portion 11C in (b). FIG. It is a disassembled perspective view of the battery module in the modification of 1st Embodiment. (A) is sectional drawing of the battery module in the modification of 1st Embodiment, (b) is an expanded sectional view of the 13B section of (a). (A) is a perspective view of a battery module according to another modification of the first embodiment, (b) is a cross-sectional view taken along line 14B-14B of (a), and (c) is a section of 14C portion of (b). It is an expanded sectional view. (A), (b) is an assembly perspective view of the battery pack in the 2nd Embodiment of this invention. It is the disassembled perspective view which showed the structure of the battery module in other embodiment of this invention. It is sectional drawing of the battery which comprises the battery module in other embodiment of this invention. (A) is sectional drawing of the battery module comprised using the battery shown in FIG. 17, (b) is an expanded sectional view of the 18B part of (a). It is sectional drawing which showed the structure of the battery module in the 3rd Embodiment of this invention. It is the disassembled perspective view which showed the structure of the battery module in the 3rd Embodiment of this invention. It is sectional drawing which showed the structure of the battery pack in the 3rd Embodiment of this invention. (A) is a cross-sectional view of the battery module disclosed in the application specification of Japanese Patent Application No. 2010-550963 (PCT / JP2010 / 004485), and (b) is an enlarged cross-sectional view of part 22B of (a).

The inventors of the present application paid attention to the fact that in the battery module 1000 shown in FIGS. 22A and 22B, the storage portion 1054 partitioned from the exhaust chamber 1024 is sealed by the wiring substrate 1030. That is, since the storage unit 1054 is in a sealed state, the gas discharged from the storage unit 1054 to the exhaust chamber 1024 does not enter the storage unit 1054 again. If the coolant is stored in advance, the coolant can be confined in the storage portion 1054. Therefore, when a plurality of battery modules 1000 are connected to form a battery pack, no coolant leaks out from the battery module 1000 no matter which direction the battery module 1000 is arranged. In addition, since the gaps of the plurality of batteries housed in the housing portion 1054 are replaced with a highly heat conductive coolant from an air layer with low heat conductivity, a significant improvement in battery cooling effect can be expected. .

DETAILED DESCRIPTION OF THE INVENTION The present invention has been made on the basis of such knowledge. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment. Moreover, it can change suitably in the range which does not deviate from the range which has the effect of this invention. Furthermore, combinations with other embodiments are possible.

(First embodiment)
FIG. 1 is a cross-sectional view schematically showing a configuration of a battery 40 used in the battery module according to the first embodiment of the present invention. The battery 40 used in the battery module of the present invention may be a battery that can be used alone as a power source for portable electronic devices such as notebook computers. In this case, since a high-performance general-purpose battery can be used as a unit cell of the battery module, it is possible to easily improve the performance and cost of the battery module.

As the battery 40 used in the battery module of the present invention, for example, a cylindrical lithium ion secondary battery as shown in FIG. 1 can be adopted. This lithium ion secondary battery has a normal configuration and includes a safety mechanism that releases gas to the outside of the battery 40 when the pressure in the battery 40 increases due to the occurrence of an internal short circuit or the like. In addition, the battery used for the battery module of this invention is not limited to this. Hereinafter, a specific configuration of the battery 40 will be described with reference to FIG.

As shown in FIG. 1, an electrode group 4 in which a positive electrode 1 and a negative electrode 2 are wound via a separator 3 is housed in a battery case 5 together with a non-aqueous electrolyte (not shown). One end of a positive electrode lead 8 is connected to the positive electrode 1, and the other end of the positive electrode lead 8 is welded to a sealing plate. One end of a negative electrode lead 9 is connected to the negative electrode 2, and the other end of the negative electrode lead 9 is welded to the bottom of the battery case 5. Insulating

plates

10a and 10b are mounted on the upper and lower sides of the electrode group 4. The open end of the battery case 5 is connected to a positive electrode cap (electrode part) 16, a current blocking member 18 such as a PTC element, a safety valve via a gasket 7. 19 and the sealing plate 6 are integrally sealed. The positive electrode 1 includes a positive electrode current collector 1a and a positive electrode mixture layer 1b containing a positive electrode active material.

The positive electrode cap 16 is provided so as to protrude from the upper surface 5A of the open end portion of the battery case 5, and an open portion 17 for releasing gas by opening the safety valve 19 is provided on the side surface of the positive electrode cap 16. Note that the amount of protrusion of the positive electrode cap 16 from the upper surface 5A is, for example, about the thickness of the separation plate described later. Further, the positive electrode cap 16 may be provided on substantially the same surface as the upper surface 5 A of the battery case 5.

The positive electrode mixture layer 1b includes, for example, lithium-containing composite oxide such as LiCoO ₂ , LiNiO ₂ , Li ₂ MnO ₄ , or a mixture or composite compound thereof as a positive electrode active material. The positive electrode mixture layer 1b further includes a conductive agent and a binder. Examples of the conductive agent include natural graphite and artificial graphite graphite, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and other carbon blacks, and examples of the binder include PVDF. , Polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide and the like.

Also, as the positive electrode current collector 1a used for the positive electrode 1, aluminum (Al), carbon (C), conductive resin, or the like can be used.

As the non-aqueous electrolyte, an electrolyte solution in which a solute is dissolved in an organic solvent, or a so-called polymer electrolyte layer containing these and non-fluidized with a polymer can be applied. As the solute of the non-aqueous electrolyte, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAlCl ₄ , LiSbF ₆ , LiSCN, LiCF ₃ SO ₃ , LiN (CF ₃ CO ₂ ), LiN (CF ₃ SO ₂ ) _2, etc. should be used. Can do. Furthermore, as an organic solvent, ethylene carbonate (EC), propylene carbonate, butylene carbonate, vinylene carbonate, dimethyl carbonate (DMC), diethyl carbonate, ethyl methyl carbonate (EMC), etc. can be used, for example.

The negative electrode current collector 11 of the negative electrode 2 is made of a metal foil such as stainless steel, nickel, copper, or titanium, or a thin film of carbon or conductive resin.

As the negative electrode mixture layer 15 of the negative electrode 2, a carbon material such as graphite, or a negative electrode active material that reversibly occludes and releases lithium ions such as silicon (Si) or tin (Sn) can be used.

Next, the configuration of the battery module 100 in the present embodiment will be described with reference to FIGS. 2 and 3.

2A is a perspective view of the battery module 100 in the present embodiment, FIG. 2B is a cross-sectional view taken along line 2B-2B of FIG. 2A, and FIG. 2C is FIG. 2C is an enlarged cross-sectional view of a portion 2C. FIG. 3 is an exploded perspective view of the battery module 100 in the present embodiment.

As shown in FIG. 2B, the battery module 100 includes a plurality of batteries 40 arranged in a housing 50. In addition, the battery 40 has the open part 17 which discharges | emits the gas generated in the battery 40 out of the battery 40 in the positive electrode cap 16 of the battery 40, as shown in FIG.2 (c).

As shown in FIG. 2B, the housing 50 accommodates a plurality of batteries 40 by the separation plate 30 disposed in contact with the upper surface 5 A of the battery case 5 around the positive electrode cap 16 of the batteries 40. And an exhaust chamber 24 for exhausting the gas discharged from the open portion 17 of the positive electrode cap 16 to the outside of the housing 50. The storage portion 54 stores a coolant (not shown) filled in the gaps between the plurality of batteries 40.

Further, as shown in FIG. 2C, the open portion 17 of the positive electrode cap 16 communicates with the exhaust chamber 24 through a through hole 36 formed in the separation plate 30. That is, the positive electrode cap 16 protruding from the battery case 5 is inserted into a through hole 36 provided corresponding to each battery 40 of the separation plate 30. At this time, the separation plate 30 is in close contact with the battery case 5, and the through hole 36 has a gap 36 A so as not to block the open portion 17 provided on the side surface of the positive electrode cap 16. Due to this gap 36 A, a defect occurs in the battery, and a space is formed in which the gas ejected from the open portion 17 of the positive electrode cap 16 is discharged. The ejected gas is discharged into the exhaust chamber 24 through the gap 36A with the through hole 36 of the separation plate 30 and further formed in the housing 50 as shown in FIGS. It is discharged from the opening 26 to the outside.

With such a configuration, the discharge space of the gas ejected from the open portion 17 of the positive electrode cap 16 can be limited in the through hole 36, so that the gas discharged into the exhaust chamber 24 through the through hole 36 is adjacent to the battery. The battery 40 in the storage unit 54 can be efficiently cooled by the coolant stored in the storage unit 54 while preventing the battery 40 from entering again. This realizes a small and thin battery module 100 that can suppress the influence on the surrounding battery 40 due to abnormal heat generation of the defective battery 40 and can cool the plurality of batteries 40 efficiently. can do. Since the storage portion 54 is hermetically sealed by the separation plate 30, the battery module 100 is arranged in any direction when the battery module 100 is arranged when the battery pack 100 is configured by connecting the plurality of battery modules 100. No coolant leaks out.

The coolant used in the present invention is not particularly limited, but it is preferable to use a material having high thermal conductivity or a material having a large heat capacity. Further, the form of the coolant is preferably a liquid, powder, gel or the like with good filling properties. As the coolant, for example, liquid, powder containing water, PP / Mg (OH) ₂ , NaHCO ₃ , Al (OH) ₃ , Mg (OH) ₂ , Na ₂ O · mSiO ₂ · nH ₂ O, etc. And gel-like.

In the present embodiment, the storage portion 54 that houses the battery 40 and the exhaust chamber 24 that exhausts the gas discharged from the open portion 17 of the battery 40 are partitioned by the separation plate 30. The board 30 may be composed of a wiring board, and a function of electrically connecting the electrodes of the plurality of batteries 40 may be added.

In this case, as shown in FIG. 3, the wiring board 30 has a connection body 32 connected to the positive electrode cap 16 of each battery 40 inserted in the through hole 36 and a connection body connecting the other electrode (negative electrode) in parallel. 34. The connection body 34 is connected to a connection plate 33 connected to the bottom of each battery 40 via an extending portion 33A. The connecting body 32 is provided across the through hole 36 so as not to completely block the through hole 36. In addition, the connection body 32 and the connection board 33 are comprised, for example with a nickel plate, Cu board, Al plate, etc., and the connection body 34 is comprised with copper foil etc., for example. Moreover, the positive electrode cap 16 and the connection body 32, and the negative electrode and the connection plate 33 are connected by, for example, electric welding or spot welding.

With such a configuration, each battery 40 constituting the battery module 100 can be connected via the wiring board 30, so that the space required for routing power supply wiring, control wiring, etc. can be greatly reduced.

Further, as shown in FIG. 2C, the wiring substrate 30 has a laminated structure of a heat-resistant member 30a made of, for example, a glass-epoxy substrate or polyimide, and a rubber elastic elastic member 30b having, for example, waterproof performance. Have Since the elastic member 30b is elastically deformed and brought into close contact with the upper surface 5A of the battery case 5, high airtightness can be ensured. Thereby, it is possible to more reliably prevent the coolant from leaking from the through hole 36 to the exhaust chamber 24 side.

Here, as shown in FIG. 3, the housing 50 has an opening end on the side to be fitted with the lid 20, and has a storage portion 54 for storing a plurality of batteries 40 from the opening end side. At this time, when the battery 40 has, for example, an outer diameter of 18 mm and a height of 65 mm, the height of the storage portion 54 is about 65 mm plus the thickness of the connection plate 33. Moreover, the cover body 20 is provided with the opening part 26 provided in a part of outer peripheral wall 22, as shown to Fig.2 (a), b).

Next, the operation and effect of the battery module 100 when abnormal heat generation or the like occurs in one battery in the battery modules connected in parallel in the battery module 100 of the present embodiment will be described with reference to FIG.

FIG. 4A is a cross-sectional view of the battery module 100 in the present embodiment, and FIG. 4B is an enlarged cross-sectional view of a portion 4B of FIG. 4A.

As shown in FIG. 4B, when one battery 40 in the battery module 100 abnormally generates heat and gas is generated in the battery case, the safety valve is activated and the gas 45 is ejected from the battery case. The ejected gas 45 is ejected from the opening portion 17 of the positive electrode cap 16 into the gap 36A of the through hole 36 in which the positive electrode cap 16 is inserted.

Next, as shown in FIG. 4A, the gas 45 is exhausted into the exhaust chamber 24 from between the through holes 36 formed in the separation plate 30 without filling the gap 36A. Then, it is finally discharged from the opening 26 provided in the lid 20 to the outside of the battery module 100. At this time, when the gas 45 suddenly ejects from the defective battery of the battery module 100, smoke or the like may be generated due to ignition or the like.

However, according to the battery module 100 of the present invention, the amount of oxygen in the gap 36A in the through hole 36 is limited, and further, oxygen is not supplied from the outside, so the possibility of igniting the gas becomes extremely low. As a result, the gas 45 is exhausted from the through hole 36 of the separation plate 30. Therefore, explosive expansion due to gas ignition does not occur, so that the battery module can be prevented from bursting.

In addition, the amount of heat of the battery 40 causing abnormal heat generation is efficiently cooled by the coolant stored in the storage portion 54.

In the present embodiment, an insulating material such as a polycarbonate resin is used for the lid 20, but the present invention is not limited to this. For example, a metal material such as aluminum or a structure in which it is coated with an insulating resin may be used. As a result, the mechanical strength can be improved, the lid can be made thinner, and the battery module can be further miniaturized. In addition, due to the high thermal conductivity of the metal material, the cooling property of the gas to be ejected is improved, and a highly reliable battery module that is unlikely to cause ignition is obtained. Furthermore, it is possible to prevent the generation of holes due to the melting of the lid 20 by the high-temperature gas that is ejected, and to prevent ignition due to the supply of oxygen from the holes.

In this embodiment, an insulating resin material such as polycarbonate resin is used for the housing 50. However, the present invention is not limited to this. For example, a conductive metal material such as nickel or copper may be used. Thereby, not only the amount of heat from the battery 40 that has abnormally heated can be made uniform, but also the heat can be radiated from the metal casing 50.

Further, the metal casing 50 may be connected to a heat radiating part 56 such as a heat sink via a heat conducting part such as a graphite sheet. Thereby, the calorie | heat amount of the battery 40 which heated abnormally can be discharged | emitted immediately.

Also, a heating part may be connected to a heat conduction part such as a graphite sheet. Thereby, when the battery module 100 is cooled, heat from the heating unit is conducted to the metal casing 50, and the plurality of batteries 40 in the battery module 100 are uniformly heated through the coolant. can do.

Further, in the present embodiment, in the casing 50 made of an insulating resin material such as polycarbonate resin, the bottom part on the negative electrode side is connected in parallel by the connection plate 33, but the casing made of a conductive metal material such as nickel or copper is used. You may connect with the connection body 34 provided in the wiring board 30 through the extending | stretching part extended in parallel with the body 50 and extended from some housing | casing 50. FIG.

In the present embodiment, the separation plate 30 is held by the outer peripheral wall 22 of the lid 20, the casing 50, and the upper surface 5 A of each battery case 5 by fitting the casing 50 and the lid 20. For example, as shown in FIG. 5, a support member 65 that supports the separation plate 30 may be interposed between the lid 20 and the separation plate 30. At this time, the support member 65 includes an outer peripheral frame 66 that supports the outer peripheral portion of the separation plate 30, and a support portion 68 that is provided at a position facing the contact position between the housing 50 and the upper surface 5 A of each battery case 5. Composed. When the space of the exhaust chamber is narrowed by the support portion 68 of the support member 65, a recess or a hole may be provided in a part of the support portion 68 so as to communicate with the opening of the lid body 20. Thereby, the separation plate 30 can be reliably fixed by the housing 50, the upper surface 5 A of each battery case 5, and the support portion 68 of the support member 65. As a result, it is possible to suppress the deformation of the separation plate 30 due to the pressure of the ejected gas, and further suppress the heat and gas intrusion into the adjacent battery.

Further, instead of providing the support member 65, as shown in FIG. 6, a rib having an opening hole 28 A in the exhaust chamber 24 of the lid 20 at a position facing the housing 50 and the upper surface 5 A of each battery case 5. A portion 28 may be provided. Thereby, while being able to fix the separation plate 30 with the housing | casing, the upper surface 5A of each battery case 5, and the rib part 28 of the cover body 20, a battery module can be made smaller or thin.

In the present embodiment, when the separation plate 30 is formed of a wiring board, for example, a voltage for detecting the voltage of each battery 40 in addition to the connection bodies (power wirings) 32 and 34 that connect the electrodes of each battery 40. You may further provide a detection wiring and the temperature detection wiring which detects temperature. At this time, for example, a temperature detection element such as a thermistor is connected to the temperature detection wiring, and the temperature can be detected by bringing the temperature detection element into contact with each battery 40. Thereby, the voltage and temperature of the plurality of batteries 40 can be individually detected and controlled. As a result, the battery 40 can be controlled in consideration of variations in characteristics, changes with time, and the like, so that reliability and safety can be further improved.

Note that the pattern width of the voltage detection wiring and temperature detection wiring on the wiring board can be significantly narrower than the pattern width of the power supply wiring. This is because a large current flows through the power supply wiring, so that it is necessary to reduce the power loss due to the wiring resistance, but the voltage detection wiring and the temperature detection wiring can be detected with a very small current. Therefore, the power supply wiring, the plurality of pairs of voltage detection wiring, and the temperature detection wiring can be efficiently arranged and formed on the wiring board, so that the space required for wiring can be greatly reduced.

In the present embodiment, the casing 50 having an open end on one side is used. However, as shown in FIG. 7, for example, a frame 50A having open ends on both ends, and a closing member that closes one open end. You may use the housing | casing 50 which has 50B. Thereby, the assemblability and workability such as the connection between each battery 40 and the wiring board or the connection plate can be improved, and a battery module excellent in productivity can be realized. Furthermore, the frame body 50A is made of an insulating resin material such as polycarbonate resin, and the closing member 50B is made of a conductive metal material such as nickel or copper. Heat can be released and input by the unit.

Further, instead of the frame body 50A, as shown in FIG. 8, a frame body 50C having partition walls 52 for individually storing the batteries 40 may be used. Thereby, since heat transfer and heat dissipation to the battery 40 adjacent to the battery 40 that has abnormally generated heat can be suppressed by the partition wall portion 52, a battery module with higher reliability and safety can be realized.

In the present embodiment, the size of the through hole 36 formed in the separation plate 30 is the same in the thickness direction. For example, as illustrated in FIG. 9, the through hole 36 in close contact with the upper surface 5 A of the battery case. The size may be smaller than the size of the through hole 36 on the connection body 32 side. Thereby, the discharge efficiency of the gas ejected from the open portion 17 of the positive electrode cap 16 into the exhaust chamber 24 can be increased (discharge resistance can be reduced). Furthermore, the contact area with the upper surface 5 A of the battery case can be expanded to further improve the sealing performance of the storage portion 54.

In the present embodiment, as shown in FIG. 3, the

connection bodies

32 and 34 are arranged on the upper surface of the wiring board 30 and the extending portion 33 A is connected to the connection body 34. The connecting body 34 may be disposed on the side surface, and the extending portion 33 A may be connected to the connecting body 34. Thereby, since it is not necessary to arrange | position extending part 33A above the wiring board 30, the sealing performance of the accommodating part 54 by the wiring board 30 can be improved more.

(Modification of the first embodiment)
FIG. 10 is a cross-sectional view of a battery constituting the battery module according to the modification of the first embodiment.

As shown in FIG. 10, the battery is configured by providing an open portion 77 on the upper surface of the positive electrode cap 16 of the battery, which is different from the battery of the first embodiment. In addition, since components other than the battery are the same as those in the first embodiment, description thereof is omitted.

A battery module 200 configured using the battery of this modification will be described with reference to FIGS. In addition, in this modification, it demonstrates using the example which comprised the separating plate 30 with the wiring board.

FIG. 11A is a perspective view of the battery module 200 in this modification, FIG. 11B is a cross-sectional view taken along the line 11B-11B in FIG. 11A, and FIG. 11C is a cross-sectional view of FIG. It is an expanded sectional view of the 11C section. FIG. 12 is an exploded perspective view of the battery module 200 in the present modification.

As shown in FIGS. 11A and 12, the battery module 200 includes a casing 50 made of an insulating resin material or a metal material whose surface is covered with a resin and subjected to an insulation process, and a lid body fitted to the casing 50. 20.

As shown in FIGS. 11B and 12, a battery unit in which the positive electrode caps 16 of the plurality of batteries 40 are arranged in the same direction is stored in the storage portion 54 of the housing 50, and the plurality of batteries 40 are connected to the wiring board. Thirty

connection bodies

32 and 34 are electrically connected in parallel. Here, the connection body 34 is connected to the connection plate 33 in which the bottom part which is one electrode part (negative electrode) of the battery 40 is connected in parallel via the extending part 33A. The housing 50 is partitioned into a storage portion 54 and an exhaust chamber 24 by the wiring board 30, and the storage portion 54 stores a coolant filled in a gap between the plurality of batteries 40.

As shown in FIG. 11C, the positive electrode cap 16 protruding from the battery case 5 is inserted into a through hole 36 provided in the wiring board 30 and connected to the connection body 32 of the wiring board 30. The wiring board 30 is in close contact with the battery case 5, and the through hole 36 has a gap 36 A between the positive electrode cap 16 and the through hole 36. At this time, the connection body 32 has a through hole 32 a at a position corresponding to the opening portion 77 so as not to block the opening portion 77 formed on the upper surface of the positive electrode cap 16. The gas ejected from the open portion 77 of the positive electrode cap 16 is discharged from the through hole 32 a to the exhaust chamber 24, and is further discharged to the outside from the opening 26 provided in the lid body 20.

As shown in FIG. 11C and FIG. 12, the wiring board 30 has a laminated structure of a heat-resistant member 30a made of, for example, a glass-epoxy substrate or polyimide, and a rubber elastic elastic member 30b having, for example, waterproof performance. Have The elastic member 30b elastically deforms and comes into close contact with the upper surface 5A of the battery case 5 to ensure high airtightness. Thereby, the coolant does not leak from the through hole 36 into the exhaust chamber 24.

The wiring board 30 is formed by extending a connection body 32 connected to the positive electrode cap 16 of each battery of the battery module inserted into the through hole 36 and a connection plate 33 connecting the other electrode (for example, negative electrode) of each battery in parallel. A connecting body 34 connected to the portion 33A is provided, and the connecting body 32 is provided with a through hole 32a so as not to block the opening 77 of the positive electrode cap 16.

Since each battery 40 constituting the battery module can be connected via the wiring board 30, it is possible to greatly reduce the space required for routing power supply wiring and control wiring. Further, since the open portion 77 of the positive electrode cap 16 of each battery 40 communicates with the exhaust chamber 24 through the through hole 32 a of the connection body 32, the gas ejected from the battery 40 does not directly eject to the wiring board 30. Therefore, deformation of the wiring board 30 can be prevented. Therefore, even if the gas emits smoke due to ignition, it is possible to prevent intrusion of gas or smoke into the adjacent battery case.

13 (a) and 13 (b), in the battery module 200 of the present modification, the operational effect of the battery module 200 when abnormal heat generation or the like occurs in one battery in the battery modules connected in parallel. explain. Here, FIG. 13A is a cross-sectional view of the battery module 200, and FIG. 13B is an enlarged cross-sectional view of a portion 13B of FIG. 13A.

As shown in FIG. 13B, one battery of the battery module 200 generates heat abnormally, and the gas generated in the battery case is activated by the safety valve and the gas 45 is ejected from the battery case 5.

As shown in FIG. 13 (a), the jetted gas 45 is jetted from the opening 77 of the positive electrode cap 16 into the exhaust chamber 24 through the through hole 32 a of the connection body 32. Then, it is finally discharged from the opening 26 provided in the lid 20 to the outside of the battery module 200.

According to the battery module 200 of the present modified example, the gas 45 is exhausted from the through hole 32a of the connection body 32 of the wiring board 30. Therefore, explosive expansion due to gas ignition does not occur, and the battery module can be prevented from bursting.

Further, the amount of heat of the battery that has caused abnormal heat generation is cooled by the coolant in the storage unit 54 so as to be averaged.

In this modification, the configuration in which the gap 36A is provided between the through hole 36 of the wiring substrate 30 into which the positive electrode cap 16 is inserted and the positive electrode cap 16 has been described as an example. For example, as illustrated in FIG. A through hole 36 having substantially the same shape as the cap 16 may be used. Thereby, positioning with the open part 77 of each battery 40 and the through-hole 32a of the connection body 32 is easy, and the dispersion | variation in the opening area of the through-hole 32a by position shift can be suppressed. As a result, it is possible to realize a battery module that is further excellent in reliability and safety.

(Second Embodiment)
A plurality of battery modules in the present invention can be arranged and connected in series and / or in parallel to form a battery pack.

FIGS. 15A and 15B are assembled perspective views of the battery pack according to the second embodiment of the present invention.

FIG. 15A shows a battery pack 400 in which four battery modules of the above embodiment are arranged side by side and connected by a connecting member 450. FIG. 15B shows a battery pack 500 in which two battery modules of the above-described embodiment are juxtaposed and connected vertically by two connecting members 550. At this time, the battery packs are configured by connecting the battery modules in parallel connection or series connection, or a combination of series connection and parallel connection.

According to the present embodiment, it can be easily realized by arbitrarily combining battery packs with high versatility having necessary voltages and electric capacities in consideration of the arrangement space according to applications.

In addition, according to the present embodiment, even if a failure occurs in any of the battery modules, the gas to be ejected can be exhausted to the outside without being ignited. As a result, since explosive expansion due to gas ignition does not occur, the battery module can be prevented from rupture, and a safe and highly reliable battery pack can be realized.

Further, in the battery module according to the present embodiment, the housing portion that houses a plurality of batteries is hermetically sealed by the wiring board. Therefore, the battery module need not be arranged so that the open surface of the housing 50 is the upper surface. The coolant stored in the storage section does not leak out. Therefore, the battery pack can be configured while combining the battery modules in a vertical position and / or a horizontal position in accordance with restrictions on the space in which the battery pack is accommodated.

(Other embodiment of a battery module)
Below, the structure of the battery module in other embodiment of this invention is demonstrated.

FIG. 16 is an exploded perspective view illustrating a battery module 600 according to another embodiment of the present invention.

In the battery module 600 according to this embodiment, a plurality of battery units 640 in which a plurality of batteries are connected in parallel are arranged in parallel, and an assembled battery unit 645 in which these battery units 640 are connected in series is housed in a housing 660. This is different from the above embodiment.

FIG. 16 shows an example of a battery module 600 in which seven battery units 640 each having one battery connected in parallel are arranged in parallel and connected in series. For example, when the battery is composed of a lithium ion battery having a capacity of 2500 mAh and an average voltage of 3.6 V, a battery module 600 having a capacity of 27.5 Ah (2.5 Ah × 11) at 25.2 V (3.6 V × 7). Is obtained.

As shown in FIG. 16, the battery module 600 according to the present embodiment includes an assembled battery unit 645 housed in a housing 660, and the housing 660 is assembled by a wiring substrate 630 (11 × 7 = 77 pieces). Of the battery) and an exhaust chamber for exhausting the gas discharged from the open part of the electrode part of the battery. Further, the storage portion stores a coolant filled in the gaps of the plurality of batteries.

The wiring board 630 has through holes 636 at positions corresponding to the positive caps of the batteries of the assembled battery unit 645, and the positive caps of the battery units 640 are connected in parallel so as not to completely block the through holes 636. A connection body 632 is provided. In addition, the wiring board 630 is disposed in close contact with the upper surface of the battery case.

Further, at the bottom of each battery of each battery unit 640, a connection plate 650 that connects the negative electrode portions in parallel is provided, and an extending portion 650A provided in a part of the connection plate 650 is connected to the connection body 632 of the adjacent battery unit 640. Each battery unit 640 is connected in series by connecting to the connected connection portion 635.

The lid 620 is provided with an opening (not shown) for discharging the gas to be ejected to the outside through an exhaust chamber (not shown). At this time, the opening may be provided individually corresponding to each battery unit 640 or may be provided integrally.

According to the present embodiment, a battery module further reduced in size can be realized by integrating the housing 660.

In this embodiment, an insulating resin material such as a polycarbonate resin is used for the housing 660. However, the present invention is not limited to this. For example, a conductive metal material such as nickel or copper may be used. In this case, instead of the connection plate 650, the negative electrode part of each battery of the battery unit 640 can be connected in parallel using the conductive case 660, and the extended part extended from a part of the conductive case 660 Each battery unit 640 can be connected in series by connecting 650A with the connection body 632 of the adjacent battery unit 640. Thereby, the number of connection bodies 632 and extending portions 650A can be reduced, and the number of parts can be reduced.

FIG. 17 is a cross-sectional view of a battery constituting a battery module according to another embodiment of the present invention. FIG. 18A is a cross-sectional view of a battery module 700 configured using the battery shown in FIG. FIG. 18B is an enlarged cross-sectional view of a portion 18B in FIG.

As shown in FIG. 17, the battery is configured by providing the battery positive cap 16 on substantially the same surface as the upper surface 5 A of the battery case 5, which is different from the battery of the first embodiment.

In addition, as shown in FIG. 18, in the through hole 36 provided in the wiring board 30, a part of the connection body 32 formed on the wiring board 30 has a convex portion 32 C protruding toward the positive electrode cap 16 side. The convex portion 32 C is connected to the positive electrode cap 16. Thereby, irrespective of the position of the positive electrode cap 16, the thin and small battery module 700 is realizable.

(Third embodiment)
In the battery module 100 according to the first embodiment, the casing 50 accommodates the plurality of batteries 40 by the separation plate 30 disposed in contact with the battery case around the positive electrode cap (electrode part) 16 of the battery 40. The storage section 54 and the exhaust chamber 24 for exhausting the gas exhausted from the open section 17 of the positive electrode cap 16 to the outside of the housing 50 are characterized in that it is partitioned. That is, the storage portion 54 that houses the plurality of batteries 40 is hermetically sealed by the separation plate 30.

Therefore, from the viewpoint of preventing the gas discharged from the open portion 17 of the positive electrode cap 16 from entering the adjacent battery 40 again, the exhaust chamber 24 is not necessarily provided in the housing 50.

FIG. 19 is a cross-sectional view showing a configuration of a battery module 800 according to the third embodiment of the present invention, and FIG. 20 is an exploded perspective view thereof, which is characterized by a structure having no exhaust chamber in the housing.

As shown in FIGS. 19 and 20, in the battery module 800 in the present embodiment, a plurality of batteries 40 are arranged and accommodated in a case 80, and the battery 40 is placed in the positive electrode cap 16 within the battery 40. An open portion (not shown) for discharging the generated gas to the outside of the battery 40 is provided.

The case 80 is formed of a cylindrical case whose upper and lower surfaces are open (in this embodiment, a cylindrical case having a rectangular cross section), and the first flat plate 81 is in contact with the upper end of the side wall of the case 80. A second flat plate 82 is disposed in contact with the lower end of the side wall of the case 80.

The plurality of batteries 40 are accommodated in the case 80 with the battery case around the positive electrode cap 16 of the battery 40 in contact with the first flat plate 81, and the accommodating portion 84 that accommodates the plurality of batteries 40 includes a case. 80 side walls, a first flat plate 81, and a second flat plate 82 are hermetically sealed. The open portion 17 of the positive electrode cap 16 communicates with the outside through a through hole 83 formed in the first flat plate 81.

With such a configuration, the housing portion 84 in which the plurality of batteries 40 are housed is sealed by the side wall portion of the case 80, the first flat plate 81, and the second flat plate 82, and thus the open portion of the positive electrode cap 16. It is possible to prevent the gas discharged from the gas 17 from entering the adjacent battery 40 again.

As shown in FIG. 20, a pair of screw holes 86 and 88 are provided at the upper and lower ends of the side wall of the case 80, respectively, and at both ends of the first flat plate 81 and the second flat plate 82, respectively. By providing a pair of screw holes 85 and 87, the first flat plate 81 and the second flat plate 82 are brought into contact with the upper and lower ends of the side wall portion of the case 80, respectively, and the screw holes are joined with screws. By doing so, the battery module 800 can be easily assembled.

Here, a coolant (not shown) filled in the gaps of the plurality of batteries 40 may be stored in the sealed storage portion 84. Thereby, since the clearance gap between the some battery 40 is replaced with the coolant with high heat conductivity from the air layer with low heat conductivity, the cooling effect of the battery 40 can be improved significantly.

If the case 80 is made of an insulating material, the first flat plate 81 can be made of a conductive first bus bar. In this case, the plurality of batteries 40 can be connected in parallel by connecting the positive electrode caps 16 of the plurality of batteries 40 to the first bus bar. Further, the second flat plate 82 can be formed of a conductive second bus bar. In this case, the plurality of batteries 40 can be connected in parallel by connecting the other electrode portions (negative electrode portions) of the plurality of batteries 40 to the second bus bar. Thereby, the thin and small battery module 800 is realizable.

A plurality of battery modules 800 in the present embodiment can be arranged and connected in series and / or in parallel to form a battery pack.

FIG. 21 is a cross-sectional view showing the configuration of the battery pack in the present embodiment.

As shown in FIG. 21, a plurality of battery modules 800 are accommodated in a housing 90, and an exhaust chamber 91 that is partitioned from a storage portion 84 of each battery module 800 is provided in the housing 90. And the gas discharged | emitted from the open part of the positive electrode cap 16 of each battery 40 accommodated in each battery module 800 is discharged | emitted by the exhaust hole 91 through the through-hole 83, and also the opening provided in the housing 90 It is discharged from the portion 92 to the outside.

In addition, when the 1st flat plate 81 and the 2nd flat plate 82 are respectively comprised by the 1st bus-bar (positive electrode terminal) and the 2nd bus-bar (negative electrode terminal), as shown in FIG. An extended portion 81 a extending toward the second bus bar 82 along the side wall portion of the housing 90 is provided at the end of the second bus bar 82, and the end of the second bus bar 82 is opposite to the first bus bar 81. If the extending portion 82a extending to the first battery module 800 is provided, the adjacent battery modules 800 are connected to the extended portion 81a provided on one battery module 800 and the other battery module 800 as shown in FIG. It is possible to easily connect in series by joining the provided extending portion 82a.

As mentioned above, although this invention has been demonstrated by suitable embodiment, such description is not a limitation matter and of course various modifications are possible. For example, in the above embodiment, the battery 40 is a lithium ion secondary battery, but other secondary batteries (for example, nickel metal hydride batteries) may be used. Moreover, in the said embodiment, although the cylindrical battery was demonstrated to the example, it is not restricted to this, For example, a square battery may be sufficient.

The present invention is useful as a power source for driving automobiles, electric motorcycles, electric playground equipment and the like.

1 Positive electrode
1a Positive electrode current collector
1b Positive electrode mixture layer
2 Negative electrode
3 Separator
4 Electrode group
5 Battery case
6 Sealing plate
7 Gasket
8 Positive lead
9 Negative lead
10a, 10b Insulating plate
11 Negative electrode current collector
15 Negative electrode mixture layer
16 Electrode (positive electrode cap)
17, 77 Opening part
18 Current interrupting member
19 Safety valve
20 Lid
22 outer wall
24 Exhaust chamber
26 opening
28 Ribs
30 Separator (wiring board)
30a Heat resistant member
30b Elastic member
32, 34 connector
33 Connection board
33A Stretched part
36 Through hole
36A clearance
40 batteries
45 gas
50 cases
54 compartment
65 Support member
80 cases
81 Through hole
81 First flat plate (first bus bar)
81a Extension part
82 Second flat plate (second bus bar)
82a extension
83 Through hole
84 compartment
85, 86, 87, 88 Screw holes
90 housing
91 Exhaust chamber
92 opening
100, 200, 600, 700, 800 Battery module
400, 500 battery pack
450, 550 Connecting member
620 lid
630 Wiring board
632 connection body
635 connection
636 Through hole
640 battery unit
645 Collective battery unit
650 connection board
650A Stretched part
660 housing

Claims

A battery module in which a plurality of batteries are arranged and stored in a housing,
The battery has an open part that discharges gas generated in the battery to the outside of the battery at the electrode part of the battery,
The housing includes a storage part that accommodates the plurality of batteries and a gas discharged from an open part of the electrode part by a separation plate disposed in contact with a battery case around the electrode part of the battery. It is divided into an exhaust chamber that exhausts outside the housing,
The storage unit stores a coolant filled in the gaps between the plurality of batteries,
An open part of the electrode part is a battery module which communicates with the exhaust chamber through a through hole formed in the separation plate.
The separation plate comprises a wiring board,
The battery module according to claim 1, wherein the electrode portion of the battery is connected to a connection body formed on the wiring board.
The battery module according to claim 1, wherein the electrode portion of the battery is inserted into a through hole of the separation plate.
The battery module according to claim 2, wherein the separation plate has a laminated structure of a heat-resistant member and an elastic member, and a lower surface of the elastic member is in contact with the battery case.
The battery module according to claim 2, wherein the plurality of batteries are connected in parallel by the connection body connected to an electrode portion of each battery.
The battery module according to claim 1, wherein the storage portion is hermetically sealed by the separation plate.
2. The battery module according to claim 1, wherein a heat conduction part that transmits heat generated by the battery module to a heat radiation part is connected to the housing.
The battery module according to claim 7, wherein the heat conducting portion is made of a graphite sheet.
The battery module according to claim 7, wherein a heating unit is connected to the heat conducting unit, and heat generated by the heating unit is transmitted to the casing through the heat conducting unit.
A battery pack in which a plurality of battery modules according to any one of claims 1 to 9 are arranged, wherein each battery module is connected in series and / or in parallel.
The battery pack according to claim 10, wherein a heat pipe that transmits heat generated by the battery module to a heat sink is connected to a housing of each battery module.
A battery module in which a plurality of batteries are arranged and stored in a case,
The battery has an open part that discharges gas generated in the battery to the outside of the battery at the electrode part of the battery,
The case is composed of a cylindrical case whose upper and lower surfaces are open,
A first flat plate is disposed in contact with the upper end of the side wall of the case,
A second flat plate is disposed in contact with the lower end of the side wall of the case,
In the plurality of batteries, a battery case around an electrode portion of the battery is in contact with the first flat plate, and is accommodated in the case.
The storage portion for storing the plurality of batteries is sealed by the side wall portion of the case, the first flat plate, and the second flat plate,
The open part of the electrode part communicates with the outside through a through hole formed in the first flat plate,
The battery module, wherein the sealed storage portion contains a coolant filled in a gap between the plurality of batteries.
The case is made of an insulating material,
The first flat plate is composed of a conductive first bus bar,
The battery module according to claim 12, wherein electrode portions of the plurality of batteries are connected to the first bus bar.
The second flat plate is composed of a conductive second bus bar,
14. The battery module according to claim 13, wherein other electrode portions of the plurality of batteries are connected to the second bus bar.
A battery pack in which a plurality of battery modules according to any one of claims 12 to 14 are arranged,
The plurality of battery modules are housed in a housing,
In the housing, an exhaust chamber partitioned from a storage portion of each battery module is provided,
A battery pack in which gas discharged from an open portion of an electrode portion of each battery housed in each battery module is discharged to the exhaust chamber through the through hole.
A battery module in which a plurality of batteries are arranged and stored in a case,
The battery has an open part that discharges gas generated in the battery to the outside of the battery at the electrode part of the battery,
The case is composed of a cylindrical case whose upper and lower surfaces are open,
A first flat plate is disposed in contact with the upper end of the side wall of the case,
A second flat plate is disposed in contact with the lower end of the side wall of the case,
In the plurality of batteries, a battery case around an electrode portion of the battery is in contact with the first flat plate, and is accommodated in the case.
The storage portion for storing the plurality of batteries is sealed by the side wall portion of the case, the first flat plate, and the second flat plate,
The open part of the said electrode part is a battery module connected to the exterior through the through-hole formed in the said 1st flat plate.