Battery module

Abstract

To provide a battery module capable of quickly detecting the occurrence of fluid leakage. [Solution] The battery module includes a plurality of battery cells, a holder capable of housing the plurality of battery cells, a conductor disposed between the plurality of battery cells housed in the holder, and a leak detection device electrically connected to the conductor.

Description

Technical Field

[0001] The technology of the present disclosure relates to a battery module.

Background Art

[0002] Battery modules are used in various devices. For example, the batteries used in vehicles are utilized for supplying power to electrical components mounted on the vehicle such as lamps and audio devices, and for supplying power to the motors for driving in electric vehicles (EVs) and the like. Lithium-ion batteries and the like are adopted for the battery cells included in such battery modules. However, among the battery cells including lithium-ion batteries, there are those filled with an electrolytic solution inside. In such battery cells filled with an electrolytic solution, the electrolytic solution may leak outside the battery cell due to an external impact or a temperature rise exceeding the allowable temperature of the battery cell.

[0003] Patent Document 1 below describes a method for detecting leakage of an electrolytic solution from a battery module, which comprises a battery module, a battery case for housing the battery module, a tray constituting the lower part of the battery case, a recess provided at a position facing the lower surface of the battery module of the tray, a pH sensor provided in the recess, and a water holding part capable of holding water so as to contact the pH sensor, and detecting a change in the pH value based on the reaction between the electrolytic solution included in the battery module and the water held in the water holding part by the pH sensor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] To promptly detect leakage from battery modules, it is necessary to consider the structure of the battery module and the arrangement of the battery cells. Therefore, there is room for further improvement in technology for promptly detecting leakage from battery modules.

[0006] In view of the above-mentioned problems, this disclosure aims to provide a battery module capable of promptly detecting the occurrence of liquid leakage. [Means for solving the problem]

[0007] To achieve the above objective, the battery module of claim 1 of this disclosure includes a plurality of battery cells, a holder capable of housing the plurality of battery cells, a conductor disposed between the plurality of battery cells housed in the holder, and a leak detection device electrically connected to the conductor.

[0008] In the battery module according to claim 1, the occurrence of leakage can be quickly detected by detecting when the electrolyte comes into contact with a conductive material disposed between battery cells using a leakage detection device.

[0009] The battery module according to claim 2 of the present disclosure is the battery module according to claim 1 of the present disclosure, wherein the plurality of battery cells comprises an electrode body, a housing having an opening and housing the electrode body, and a closing member that closes the opening of the housing, and the conductor is disposed adjacent to the opening of the housing.

[0010] In the battery module according to claim 2, the conductive material is positioned adjacent to an opening in the battery cell where leakage is relatively likely to occur, thereby enabling detection of leakage in a shorter time.

[0011] The battery module according to claim 3 of this disclosure is the battery module according to claim 2 of this disclosure, wherein the conductor is disposed on the outer circumferential surface of the housing adjacent to the opening.

[0012] In the battery module according to claim 3, by arranging a conductive material on the outer circumferential surface of the housing, it becomes possible to detect the occurrence of electrolyte leakage before it reaches the holder.

[0013] The battery module according to claim 4 of the present disclosure is the battery module according to claim 1 of the present disclosure, wherein the holder includes a plurality of cylindrical housing holes having openings and housing the plurality of battery cells inside, and the conductor is disposed of the holder at a position adjacent to the openings.

[0014] In the battery module according to claim 4, the installation of the conductive material is easy.

[0015] The battery module according to claim 5 of the present disclosure is the battery module according to claim 4 of the present disclosure, wherein the holder is installed such that at least a portion of the openings of the housing holes are in different positions in the vertical direction, and the conductor is disposed between the openings of the housing holes of the holder that are adjacent in the vertical direction.

[0016] In the battery module according to claim 5, leakage can be detected before the electrolyte causes a short circuit between the battery cells. [Effects of the Invention]

[0017] According to the battery module of this disclosure, leakage can be detected promptly. [Brief explanation of the drawing]

[0018] [Figure 1] This is a front view showing an example of a battery module according to one embodiment. [Figure 2] Figure 1 is a schematic cross-sectional view showing an example of a battery cell. [Figure 3] Figure 1 shows a schematic cross-sectional view taken along line AA. [Figure 4] This is an enlarged cross-sectional view showing section B in Figure 3. [Figure 5]A figure showing a modified example of a conductor, which is an enlarged view showing an enlarged position corresponding to part C in FIG. 1. [Figure 6] A figure showing another modified example of a conductor, which is an enlarged view corresponding to FIG. 3.

Embodiments for Carrying out the Invention

[0019] Hereinafter, each embodiment for implementing the present disclosure will be described with reference to the drawings. In the following, the range necessary for the description to achieve the object of the present disclosure is schematically shown, and mainly the range necessary for the description of the corresponding part of the present disclosure will be described, and the parts where the description is omitted are assumed to be based on known techniques. Also, the same or corresponding members in the drawings are denoted by the same or similar reference numerals, and redundant descriptions are omitted. Further, when a plurality of the same or corresponding members in the drawings are included, in order to make the drawings easy to view, only some of them may be denoted by reference numerals.

[0020] FIG. 1 is a front view showing an example of a battery module according to an embodiment. The battery module 1 according to the present embodiment may be mounted on a vehicle such as an electric vehicle. In the following description, the X direction shown in FIG. 1 may be described as the left - right direction, the Y direction as the front - rear direction, and the Z direction as the up - down direction. Also, the battery module 1 shown in FIG. 1 shows a state installed at a predetermined position in the vehicle.

[0021] As shown in FIG. 1, the battery module 1 according to the present embodiment includes at least a plurality of battery cells 10, a holder 20 capable of accommodating the plurality of battery cells 10, a conductor 30 disposed between the plurality of battery cells 10, and a leakage detection device 40 electrically connected to the conductor 30.

[0022] Figure 2 is a cross-sectional view showing an example of the battery cell shown in Figure 1. As shown in Figure 1, the battery cell 10 can be composed of a secondary battery containing an electrolyte, such as a lithium-ion battery. In this embodiment, a cylindrical battery cell 10 is shown as an example. This battery cell 10 may include, for example, an electrode body 11, a housing 12 having an opening 12A and housing the electrode body 11, and a closing member 13 that closes the opening 12A of the housing 12. Note that the shape and type of the battery cell 10 described above are examples and are not limited to these.

[0023] The electrode body 11 can be constructed, for example, as a wound electrode body. This electrode body 11 may have a structure in which a strip-shaped positive electrode 14 and a negative electrode 15 are wound together with a strip-shaped separator 16 interposed between them. For the positive electrode 14, metals such as cobalt, nickel, manganese, or iron phosphate-based materials can be used, either alone or in combination. For the negative electrode 15, carbon-based materials or other alloys can be used. Furthermore, a porous sheet having ion permeability and insulating properties can be used for the separator 16, and materials such as polyethylene, polyolefin resins including polypropylene, or cellulose can be used.

[0024] Furthermore, the electrolyte E1 (see Figure 3) sealed inside the battery cell 10 can be an organic solvent such as ethylene carbonate, dimethyl carbonate, or diethyl carbonate in which lithium electrolyte salts are dissolved. The materials and shapes of each component constituting the electrode body 11, the type of electrolyte E1, etc., can be appropriately selected and adopted based on the intended use of the battery module 1.

[0025] The housing 12 houses the electrode body 11 together with the electrolyte E1 and can be constructed as an outer container made of a bottomed cylindrical metal container. An opening 12A is provided at the top of the housing 12, and this opening 12A is sealed by a closing member 13 after the electrode body 11 and the electrolyte E1 are inserted into the housing 12. The housing 12 can also function as a negative electrode terminal electrically connected to the negative electrode 15 by connecting a negative electrode lead (not shown) electrically connected to the end of the wound negative electrode 15 or to an appropriate location on the negative electrode 15. The housing 12 can be manufactured by forming a bottomed cylindrical shape from a metal plate by drawing or the like. In this embodiment, the center of the bottom of the housing 12 functions as a negative electrode contact 15A. Preferably, an insulator (not shown) is wound in a cylindrical shape around the outer circumference of the housing 12 to protect it.

[0026] The blocking member 13 can be composed of a plate-shaped member that at least partially closes the opening 12A of the housing 12. The blocking member 13 in this embodiment may include a terminal plate 17 electrically connected to the positive electrode 14 and a safety valve 18 positioned opposite the terminal plate 17.

[0027] The terminal plate 17 can be made of a roughly disc-shaped plate made of metal, such as aluminum or an aluminum alloy. This terminal plate 17 may be partially joined to the safety valve 18 by welding or adhesive. In addition, insulating material may be provided at appropriate locations between the terminal plate 17 and the safety valve 18.

[0028] The safety valve 18 can be made of a roughly disc-shaped plate body with a larger diameter than the terminal plate 17. This safety valve 18 can be manufactured by press-forming a metal plate, such as aluminum or an aluminum alloy. The safety valve 18 functions as a so-called explosion-proof valve, preventing damage to the housing 12 by being pressed and inverted by the pressure when the pressure inside the housing 12 rises due to abnormal heat generation of the electrode body 11 or the like. The central part of the safety valve 18 functions as a positive electrode contact 14A. Note that the above-described configuration of the blocking member 13 is merely an example, and the specific configuration and shape of the blocking member 13 can be changed as appropriate.

[0029] The opening 12A of the housing 12 is sealed by crimping and fixing the edge of the closing member 13, which includes the above-described configuration, at a crimped portion 12B adjacent to the opening 12A. In this embodiment, the crimped portion 12B crimps and fixes the edge of the closing member 13, more specifically the outer circumference of the safety valve 18, with a gasket 19 made of a relatively flexible insulating material or the like in between. This crimping and fixing is performed by applying pressure to the crimped portion 12B along the axial direction of the battery cell 10 using a pressurizing device (not shown). The cross-sectional shape of the crimped portion 12B after crimping and fixing is a roughly U-shape with an open inner side, as shown in Figure 2. The aforementioned gasket 19 functions as a sealing material to ensure the airtightness of the battery cell 10 and as an insulator to electrically insulate the housing 12 and the terminal board 17.

[0030] In the battery cell 10 having the configuration described above, due to the structure of the housing 12, the strength near the opening 12A of the housing 12, more specifically the crimped portion 12B, is lower than that of other parts. Also, when the safety valve 18 is activated, a gap may be formed through which the electrolyte E1 leaks out. Therefore, for example, when a pressure rise occurs inside the housing 12 due to abnormal heat generation of the electrode body 11, or when it is subjected to an external impact, there is a high possibility that the electrolyte E1 inside the housing 12 will leak out of the housing 12 through the crimped portion 12B or the safety valve 18. The battery module 1 of this embodiment employs a configuration to quickly detect the occurrence of electrolyte leakage in the battery cell 10 as described above.

[0031] As shown in Figure 1, the holder 20 is capable of housing multiple battery cells 10 having the configuration described above, and may be made of an insulating material such as resin. The holder 20 can be made of a block body that is substantially rectangular in front view, and its length in the front-to-back direction should be adjusted to match the axial length of the battery cells 10 to be housed. The holder 20 is also provided with a plurality of housing holes 21 extending along the front-to-back direction. The holder 20 may be configured such that the first opening 21A, which is an example of at least some of the openings of the housing holes 21, is positioned at different locations in the vertical direction. In this embodiment, the holder 20 has a total of nine housing holes 21 arranged in a predetermined spacing, with three rows in the vertical direction and three columns in the horizontal direction.

[0032] Each of the multiple housing holes 21 provided in the holder 20 accommodates one battery cell 10. Therefore, the number of battery cells 10 housed in the holder 20 is the same as the number of housing holes 21. In this embodiment, the housing holes 21 extend in the front-rear direction, and both ends in the extending direction open to the front and back of the holder 20 as a first opening 21A and a second opening 21B. In other words, the housing holes 21 in this embodiment can be configured as through holes that penetrate the holder 20 in the front-rear direction. The multiple battery cells 10, at least a portion of which are housed in the multiple housing holes 21, are inserted into the housing holes 21 with their positive electrode contacts 14A facing the front side of the holder 20. However, the orientation of the battery cells 10 housed in the housing holes 21 is not limited to the above. For example, the multiple battery cells 10 may be housed in each housing hole 21 such that the contacts of the battery cells 10 when viewed from the front of the battery module 1 are different from those of adjacent battery cells 10. In this case, the arrangement and connection method of the busbars, as described later, may also be changed as appropriate. The first opening 21A and the second opening 21B can also function as insertion points for the battery cell 10.

[0033] Figure 3 is a schematic cross-sectional view taken along line AA shown in Figure 1. In Figure 3, for the purpose of making the diagram easier to see, only the battery cell 10 among the components of the battery module 1 is shown in a side view. As shown in Figure 3, a first cover 22 and a second cover 23 are attached to the front and back of the holder 20 of this embodiment.

[0034] The first cover 22 can be made of a plate-shaped member that covers the front of the holder 20. A positive electrode busbar 24 is installed on the surface of the first cover 22 that faces the front of the holder 20. When the first cover 22 is attached to the front of the holder 20, the positive electrode busbar 24 is positioned to face the positive electrode contact 14A of each battery cell 10 and is electrically connected to all positive electrode contacts 14A via lead terminals or the like (not shown).

[0035] The second cover 23 can be made of a plate-shaped member that covers the back of the holder 20. A negative electrode busbar 25 is installed on the surface of this second cover 23 that faces the back of the holder 20. When the second cover 23 is attached to the back of the holder 20, the negative electrode busbar 25 is positioned to face the negative electrode contact 15A of each battery cell 10 and is electrically connected to all negative electrode contacts 15A. The negative electrode busbar 25 and the positive electrode busbar 24 mentioned above may be connected to a control device (not shown) that controls the charging and discharging of the battery module 1. The first and second covers 22 and 23 may be omitted.

[0036] The conductor 30 is disposed between multiple battery cells 10 housed in the housing hole 21 of the holder 20. More preferably, the conductor 30 is disposed adjacent to the opening 12A of the housing 12 of the battery cell 10. The reason for arranging the conductor 30 adjacent to the opening 12A of the housing 12 is that, as described above, electrolyte E1 is prone to leaking from the opening 12A, and therefore, compared to when it is disposed at a location far from the opening 12A, leakage of electrolyte from the battery cell 10 can be detected more quickly. As shown in Figure 1, the conductor 30 in this embodiment is composed of multiple metal plates that are elongated in the left-right direction and are disposed adjacent to the first opening 21A of the housing hole 21 where the aforementioned opening 12A is located. When the conductor 30 is placed on the surface of the holder 20 in this way, the installation work of the conductor 30 is easy and therefore preferable.

[0037] Furthermore, it is preferable that the conductor 30 is positioned around the battery cell 10, particularly between other battery cells 10 adjacent to each other in the vertical direction when the battery module 1 is installed in the usage position. In the structure of this embodiment, it is preferable that the conductor 30 is positioned at least below the battery cell 10. This is because positioning the conductor 30 below one battery cell 10 allows the conductor 30 and the electrolyte E1 leaking and flowing down from the battery cell 10 to come into contact quickly, specifically before contacting other battery cells 10 located below that battery cell 10. In addition, although the conductor 30 in this embodiment is shown as being attached to the front surface of the holder 20 with an adhesive or the like, it may also be installed so as to be at least partially embedded in the front surface of the holder 20.

[0038] The leak detection device 40 may be electrically connected to the conductor 30 via a first conductive wire 41. This leak detection device 40 may detect leaks by detecting when the electrolyte E1 comes into contact with the conductor 30. In this embodiment, the leak detection device 40 is electrically connected to the battery cell 10, or a busbar connected to the battery cell 10, via a second conductive wire 42. The leak detection device 40 in this embodiment detects when the electrolyte E1 comes into contact with the conductor 30 by detecting a change in electrical resistance between the conductor 30 and the battery cell 10. Adopting such a detection method is preferable because it allows for the detection of leaks without connecting to the vehicle's body ground wire, etc. Note that the specific detection method of the leak detection device 40 is not limited to the above, and other methods capable of electrically detecting contact between the conductor 30 and the electrolyte E1 can be employed.

[0039] Figure 4 is an enlarged cross-sectional view showing an enlarged view of section B in Figure 3. In the battery module 1 of this embodiment having the above-described configuration, for example, as shown in Figures 3 and 4, if electrolyte E1 leaks from one of the upper battery cells 10, the leaked electrolyte E1 flows downward along the front surface of the holder 20. If the battery module 1 does not include the conductor 30 described above, as shown in Figure 4, the electrolyte E0 leaked from one of the battery cells 10 will flow down the front surface of the holder 20 and then come into contact with another battery cell 10 located below the first battery cell 10, causing a short circuit between the two battery cells 10, 10. Such a short circuit is a cause of deterioration of the battery cell 10 and is desirable to avoid. In the battery module 1 of this embodiment, the conductor 30 and the leak detection device 40 described above are employed to prevent the occurrence of the aforementioned short circuit.

[0040] To explain in more detail, the electrolyte E1 leaking from the upper battery cell 10 generally has a certain viscosity. As shown in Figure 3, after flowing out of the battery cell 10, it flows along the front surface of the holder 20, and before contacting the other battery cells 10 located in the lower row, it contacts the conductor 30 installed below the battery cell 10. When the electrolyte E1 contacts the conductor 30, an electric current flows between the battery cell 10 and the conductor 30, causing a change in the electrical resistance between the battery cell 10 and the conductor 30. The leak detection device 40 can detect that a leak has occurred in any of the battery cells 10 by detecting the aforementioned change in electrical resistance. The occurrence of a leak should be notified to the user, for example, the occupants of the vehicle, via a user interface (not shown) such as a display monitor or speaker.

[0041] It is important to note that the conductor 30 in this embodiment is positioned between the battery cells 10. By positioning the conductor 30 as described above, electrolyte E1 leaking from one battery cell 10 can come into contact with the conductor 30 before it comes into contact with an adjacent battery cell 10 and causes a short circuit between the battery cells 10, thus preventing a short circuit between them. Furthermore, while a short circuit between battery cells 10 accelerates the deterioration of the battery cells 10, the aforementioned arrangement of the conductor 30 can prevent this rapid deterioration. If leakage can be detected quickly, the leaking battery cell 10 can be repaired promptly, allowing the battery cells 10 to be used for a longer period.

[0042] Hereinafter, with reference to Figures 5 and 6, several modifications of the conductor of the battery module 1 according to the above-described embodiment will be explained. Figure 5 is a diagram showing a modified conductor, and is an enlarged view showing the position corresponding to part C in Figure 1. Figure 6 is a diagram showing another modified conductor, and is an enlarged view corresponding to Figure 3.

[0043] In the embodiment described above, an example was given in which multiple metal plates extending in the left-right direction across the lower part of multiple battery cells 10 were used as the conductor 30, but the shape and arrangement of the conductor 30 are not limited to this. Specifically, for example, as shown in the modified example in Figure 5(A), an independent conductor 30A can also be arranged at the lower part of one battery cell 10. In this way, by arranging a conductor 30A for each battery cell 10 and monitoring the insulation resistance between each conductor 30A and the battery cell 10 in the leak detection device 40, the battery cell 10 in which leakage has occurred can be immediately identified.

[0044] Furthermore, as shown in the modified example in Figure 5(B), the ring-shaped conductive material 30B can be arranged to surround the entire circumference of each battery cell 10. Adopting such a conductive material 30B increases the flexibility of the installation orientation of the battery module 1.

[0045] Furthermore, in the above-described embodiment and its various modifications, the example illustrates the case where the conductors 30, 30A, and 30B are arranged in the holder 20, but the conductors may also be arranged in the battery cell 10. Specifically, for example, as shown in Figure 6, a conductor 30C, which is made of a ring-shaped metal plate, may be arranged on the outer circumferential surface of the housing 12 adjacent to the opening 12A, via an insulating material (not shown). When leakage occurs in the battery cell 10 on which the conductor 30C is arranged, at least a portion of the electrolyte E2 leaking from the battery cell 10 can enter the area defined by the outer circumferential surface of the housing 12, the inner circumferential surface of the housing hole 21, and the conductor 30C, thereby bringing it into contact with the conductor 30C.

[0046] The same effects as those shown in the above embodiments can be achieved in the various modifications described above. It should be noted that the arrangement and shape of the conductors shown in the above embodiments and some of the modifications are merely examples, and the conductors of this disclosure are not intended to be limited to these structures.

[0047] Furthermore, in the embodiment described above, a structure is adopted in which the second cover 23 is attached to the back of the holder 20, but the second cover 23 can also be integrally formed as part of the holder 20. Also, in the embodiment described above, the accommodation holes 21 provided in the holder 20 are shown as being arranged in a straight line along the vertical direction, but the left-right positions of adjacent accommodation holes 21 in the vertical direction may be offset. In addition, the number and arrangement of the accommodation holes 21 can be changed as appropriate.

[0048] Furthermore, while the embodiments and some modifications described above illustrate a configuration in which a conductor is placed around all of the battery cells housed in the holder, it is also possible to place a conductor around only some of the battery cells 10 housed in the holder 20.

[0049] This disclosure is not limited to the embodiments described above, and can be implemented with various modifications without departing from the spirit of this disclosure. All such modifications are included in the technical concept of this disclosure. Furthermore, unless otherwise specified in the specification, each component of this disclosure is not limited to one, but may exist in multiple forms. [Explanation of Symbols]

[0050] 1 Battery Module 10 battery cells 11 Electrode body 12 cabinets 12A aperture 12B Crimping section 13. Closure member 20 holders 21 housing holes 30 Conductors 40 Leak detection device E0~E2 Electrolyte

Claims

1. Multiple battery cells, A holder capable of housing the aforementioned plurality of battery cells, A conductor is disposed between the plurality of battery cells housed in the holder, The device comprises a leak detection device electrically connected to the conductor, Battery module.

2. Each of the aforementioned plurality of battery cells comprises an electrode body, a housing having an opening and housing the electrode body, and a closing member that closes the opening. The conductor is disposed at a position adjacent to the opening. The battery module according to claim 1.

3. The conductor is disposed on the outer circumferential surface of the housing adjacent to the opening. The battery module according to claim 2.

4. The holder has an opening and comprises a plurality of cylindrical housing holes that house the plurality of battery cells inside, The conductor is disposed in the holder at a position adjacent to the opening. The battery module according to claim 1.

5. The holder is installed such that at least a portion of the openings of the housing hole are in different positions in the vertical direction. The conductor is disposed between the openings of the housing holes that are adjacent to each other in the vertical direction of the holder. The battery module according to claim 4.

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