Method for reducing pressure when sealing battery

Abstract

To provide a method for reducing pressure when sealing a battery that can suppress deformation of a liquid filling frame while being capable of thermally welding a liquid filling frame heated by a heating device to a resin member that closes a liquid filling hole.SOLUTION: A method for reducing pressure when sealing a battery includes a filling step of filling an electrolyte into an internal space and a liquid filling hole of a laminate through filling holes 27, 28 provided on an end face 25C of a resin filling frame 25 provided on the outer periphery of a laminate 15 having a plurality of electrodes, a covering step of covering the end face with a resin member 30 so as to cover the liquid filling hole, a cooling step of bringing a cooling member 56 into contact with at least one of the upper and lower faces of the liquid filling frame, a decompression step of sucking gas from at least one of the internal space and the liquid filling hole through the liquid filling hole, and a sealing step of heating the liquid filling frame through the resin member to weld the end face of the liquid filling frame to the resin member.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method for vacuum sealing a battery.

Background Art

[0002] As an example of a battery, an electrolytic solution is injected into the internal space of a laminate through a liquid injection hole provided at an end face of a resin liquid injection frame provided on the outer peripheral portion of a laminate having a negative terminal electrode, a bipolar electrode, a positive terminal electrode, and a separator. In this battery, further, gas is sucked from the internal space using the liquid injection hole, and the liquid injection frame heated by a heating device is heat-welded to a resin member, and the liquid injection hole can be closed by this resin member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When heating a resin member with a heating device, this heat may be transferred from the liquid injection frame to the electrolytic solution, and the electrolytic solution may generate gas. Further, this gas may exert pressure on the liquid injection frame, and there is a risk that the liquid injection frame may be deformed by this pressure.

[0005] In consideration of the above facts, an object of the present invention is to obtain a method for vacuum sealing a battery that can heat-weld a liquid injection frame heated by a heating device to a resin member that closes a liquid injection hole while suppressing deformation of the liquid injection frame.

Means for Solving the Problems

[0006] The pressure-reducing sealing method for a battery according to the first aspect includes a liquid injection step of injecting an electrolytic solution into the internal space of the laminate and the liquid injection hole through the liquid injection hole provided in the end face of a resin-made liquid injection frame provided on the outer peripheral portion of a laminate having a plurality of electrodes, a covering step of covering the end face with a resin member so as to cover the liquid injection hole, a cooling step of bringing a cooling member into contact with at least one of the upper surface and the lower surface of the liquid injection frame, a pressure-reducing step of sucking gas from at least one of the internal space and the liquid injection hole through the liquid injection hole, and a sealing step of heating the liquid injection frame through the resin member to weld the end face to the resin member.

[0007] The pressure-reducing sealing method for a battery according to the first aspect includes a cooling step of bringing a cooling member into contact with at least one of the upper surface and the lower surface of the liquid injection frame. Therefore, when welding the end face of the liquid injection frame heated through the resin member to the resin member, it is difficult for heat to be transferred to the electrolytic solution in the liquid injection hole. Therefore, it is possible to suppress the liquid injection frame from being deformed due to the electrolytic solution generating gas and the pressure of this gas increasing.

[0008] The pressure-reducing sealing method for a battery according to the second aspect is, in the first aspect, the cooling step is a step of bringing the cooling member into contact with a portion of the outer surface of the liquid injection frame that is aligned in the stacking direction of the liquid injection hole and the plurality of electrodes.

[0009] According to the pressure-reducing sealing method for a battery according to the second aspect, the cooling effect of the electrolytic solution in the liquid injection hole by the cooling member is increased. Therefore, it is possible to more effectively suppress the deformation of the liquid injection frame caused by the pressure of the gas generated by the electrolytic solution.

[0010] The pressure-reducing sealing method for a battery according to the third aspect is, in the first aspect or the second aspect, a step of temporarily fixing the resin member to the liquid injection frame using an adhesive temporary fixing tape, and the pressure-reducing step is a step of sucking gas from at least one of the internal space and the liquid injection hole through a gap between the resin member and the liquid injection frame in a state where the resin member is temporarily fixed to the liquid injection frame.

[0011] According to the method for vacuum sealing the battery of the third aspect, gas can be sucked from the internal space of the laminate while the resin member is temporarily fixed to the liquid injection frame.

Advantages of the Invention

[0012] As described above, the method for vacuum sealing the battery according to the present invention has an excellent effect that the liquid injection frame heated by the heating device can be heat-welded to the resin member that closes the liquid injection hole, while suppressing the deformation of the liquid injection frame.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0014] FIG. 1 shows a battery (bipolar battery) 10 manufactured by applying a method for depressurized sealing of a battery according to an embodiment (hereinafter referred to as the depressurized sealing method). The battery 10 can be mounted on various devices. For example, the battery 10 can be mounted on a battery electric vehicle (BEV) and supply power to an electric motor that is a drive source. Note that the arrows UP, FR, and LH shown in each drawing indicate the upper side in the vertical direction, the front side in the front-rear direction, and the left side in the left-right direction, respectively.

[0015] Before explaining the depressurized sealing method, the basic configuration of the battery 10 will be described with reference to FIGS. 1 and 2. The battery 10 of the present embodiment includes a laminate 15, a resin structure 20, and a cover member (resin member) 30.

[0016] The laminate 15 includes three battery cells 12. Since the configuration of the laminate 15 is well-known, the following description of the laminate 15 will be simplified. For example, the laminate 15 has the same configuration as the laminate disclosed in Japanese Unexamined Patent Application Publication No. 2023-110291. The laminate 15 includes one negative terminal electrode (electrode), one positive terminal electrode (electrode), two bipolar electrodes (electrodes) positioned between the negative terminal electrode and the positive terminal electrode, and three separators positioned between the adjacent positive terminal electrode, negative terminal electrode, and bipolar electrodes. The negative terminal electrode includes a current collector and a negative active material layer provided on one surface of the current collector. The positive terminal electrode includes a current collector and a positive active material layer provided on one surface of the current collector. Each bipolar electrode includes a current collector and negative and positive active material layers provided on both surfaces of the current collector, respectively. The laminate 15 is configured by laminating the negative terminal electrode, positive terminal electrode, two bipolar electrodes, and three separators in the lamination direction LD. In FIGS. 1 and 2, the lamination direction LD is parallel to the vertical direction. The planar shapes of the negative terminal electrode, positive terminal electrode, bipolar electrode, and separator of the present embodiment are rectangular. Therefore, as shown in FIG. 2, the planar shape of the laminate 15 is rectangular. Each separator, the negative active material layer and the positive active material layer positioned above and below the separator are components of the battery cell 12.

[0017] A frame-shaped resin component 22, which is part of the resin component 20, is provided on the outer peripheral portion of the laminate 15. The frame-shaped resin component 22 is integrated with the outer peripheral portion of the laminate 15 in an airtight and liquidtight state so as to cover the outer peripheral portion of the laminate 15. Further, three slits 23 are provided on the front end surface of the frame-shaped resin component 22. The rear end portions of the respective slits 23 communicate with the front end portions of the internal spaces of the three battery cells 12 in an airtight and liquidtight state, respectively.

[0018] A liquid injection frame 25, which is part of the resin component 20, is provided on the front end surface of the frame-shaped resin component 22 so as to cover the front side end portions of the respective slits 23. As shown in FIGS. 1 and 2, the liquid injection frame 25 has a rectangular parallelepiped shape. The upper surface 25A and the lower surface 25B of the liquid injection frame 25 are constituted by planes that are substantially parallel to each other. Further, as shown in FIGS. 3 to 6, three outer liquid injection holes (liquid injection holes) 27 extending rearward inside the liquid injection frame 25 and three inner liquid injection holes (liquid injection holes) 28 extending from the rear ends of the respective outer liquid injection holes 27 to the rear end of the liquid injection frame 25 are provided on the front end surface 25C on the front side of the liquid injection frame 25. The cross section of the outer liquid injection hole 27 perpendicular to the front-rear direction is larger than the cross section of the inner liquid injection hole 28 perpendicular to the front-rear direction. The rear end portions of the respective inner liquid injection holes 28 communicate with the front end portions of the respective slits 23 in an airtight and liquidtight state.

[0019] The frame-shaped resin component 22 and the liquid injection frame 25 are constituted by a resin material having insulating properties. The constituent materials of the frame-shaped resin component 22 and the liquid injection frame 25 are, for example, polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, or acrylonitrile styrene resin.

[0020] The frame-shaped resin component 22 and the liquid injection frame 25 may be manufactured in different manufacturing processes, or may be manufactured in a single manufacturing process. For example, a manufacturing process of providing the frame-shaped resin component 22 on the outer peripheral portion of the laminate 15 by insert molding, and a manufacturing process of providing the liquid injection frame 25 at the front end portion of the frame-shaped resin component 22 integrated with the laminate 15 by insert molding may be executed to manufacture an integrated body of the laminate 15 and the resin component 20. Further, a resin component 20 having the frame-shaped resin component 22 and the liquid injection frame 25 may be provided on the outer peripheral portion of the laminate 15 by insert molding.

[0021] An electrolytic solution (not shown) is injected into the internal space of each battery cell 12, each slit 23, each outer liquid injection hole 27, and each inner liquid injection hole 28 from the front end portion of each outer liquid injection hole 27.

[0022] After the injection of the electrolytic solution, a pressure reduction process described later is executed, and the battery 10 is completed by thermally welding the end face 25C of the liquid injection frame 25 to the cover member 30. As shown in FIG. 2, the cover member 30 is a substantially rectangular film-shaped member. The cover member 30 is made of a resin material having insulating properties. The resin material constituting the cover member 30 is, for example, polypropylene, polyethylene, or polyamide.

[0023] Subsequently, the pressure reduction sealing method of the present embodiment will be described with reference to FIGS. 3 to 7. As shown in FIG. 7, the pressure reduction sealing method of the present embodiment includes a loading process, a liquid injection process, a coating process, a cooling process, a pressure reduction process, a sealing process, a sealing end process, a pressure reduction end process, and a cooling end process. By repeatedly executing these processes, a plurality of batteries 10 are manufactured.

[0024] The pressure reduction sealing method of the present embodiment is executed while using a pressure reduction sealing device 40. The pressure reduction sealing device 40 includes a chamber 41, a support base 45, a pipe 47, a suction device 48, a heating device 50, and a cooling device 55.

[0025] The chamber 41 is a rectangular parallelepiped box-shaped member. A through hole (not shown) is formed in the upper part of the chamber 41. Further, the chamber 41 is provided with a lid member (not shown) that detachably closes the through hole in an airtight state. A first hole 43 and a second hole 44 are provided side by side vertically on the front wall 42 of the chamber 41. Further, a support base 45 is fixed to the bottom surface of the internal space of the chamber 41. The support surface 46, which is the upper surface of the support base 45, is inclined with respect to the horizontal plane.

[0026] A pipe 47 is inserted into the first hole 43 of the front wall 42. An airtight state is maintained between the inner peripheral surface of the first hole 43 and the outer peripheral surface of the pipe 47. A suction device 48 is connected to the front end portion of the pipe 47.

[0027] A heating device 50 is connected to the second hole 44 of the front wall 42. The heating device 50 includes a slider 51, a heating portion 52, and a first actuator (not shown). The slider 51 is slidably inserted into the second hole 44. An airtight state is maintained between the inner peripheral surface of the second hole 44 and the outer peripheral surface of the slider 51. In a side view, the slider 51 is inclined with respect to the horizontal direction. The slider 51 is slidable with respect to the front wall 42 in the extension direction of the slider 51 (the direction of arrow DR in FIGS. 3 to 6). A first actuator is connected to the slider 51. By the driving force generated by the first actuator, the slider 51 is slidable between the initial position shown in FIGS. 3 and 6 and the maximum pushing position shown in FIG. 5. A heating portion 52 is fixed to the rear end portion of the slider 51. The heating surface 53, which is the rear surface of the heating portion 52, is constituted by a flat surface. Further, a heat generating portion (not shown) for heating the heating portion 52 (heating surface 53) is provided inside the heating portion 52. The heat generating portion is, for example, a heating wire that generates heat when an electric current flows.

[0028] A cooling device 55 is provided in the internal space of the chamber 41. The cooling device 55 has a pair of upper and lower cooling members 56 and a second actuator (not shown). The opposing surfaces of the upper and lower cooling members 56 are constituted by contact surfaces 57 which are flat. Inside the cooling member 56, a cooling source (not shown) for cooling the cooling member 56 (contact surface 57) is provided. The cooling source is, for example, a liquid refrigerant that is supplied from a supply source (not shown) provided outside the chamber 41 through a liquid supply pipe that extends and penetrates the wall of the chamber 41 into an internal flow path formed inside the cooling member 56. Due to the driving force generated by the second actuator, the upper and lower cooling members 56 can reciprocate in directions approaching each other and separating from each other. That is, each cooling member 56 can slide between the contact positions shown in FIGS. 3 to 5 and the initial position shown in FIG. 6.

[0029] When executing a vacuum sealing method using the vacuum sealing device 40, first, as shown in FIG. 7, a liquid injection step is carried out. That is, an electrolytic solution is injected into the internal space of each battery cell 12, each slit 23, each inner liquid injection hole 28, and each outer liquid injection hole 27 through the front end portions of each outer liquid injection hole 27.

[0030] Subsequently, a loading step is carried out. That is, an integrated object having the laminate 15 and the resin structure 20 is inserted into the internal space of the chamber 41 through the through hole of the chamber 41 in a state where the lid member is removed, and as shown in FIG. 3, the lower surface of the integrated object is placed on the support surface 46 of the support base 45 in a manner such that the liquid injection frame 25 faces the heating portion 52 in the front-rear direction, and the integrated object and the support base 45 are fixed. Thereby, the front end portion of the integrated object is positioned above the rear end portion. At this time, the heating portion 52 and the cooling member 56 are located at their respective initial positions.

[0031] Subsequently, a covering step is carried out. That is, a cover member 30 is placed on the end surface 25C of the liquid injection frame 25 so as to cover each outer liquid injection hole 27. Further, a plurality of locations of the cover member 30 are temporarily fixed to the liquid injection frame 25 using an adhesive temporary fixing tape 60 (see FIG. 2). This temporary fixing tape 60 is made of a material with high heat resistance.

[0032] Subsequently, a cooling process is performed. That is, a pair of cooling members 56 located at the initial position and cooled to a predetermined temperature are moved to the contact position as shown in FIG. 3 using the second actuator. As a result, the contact surface 57 of the upper cooling member 56 comes into surface contact with the upper surface 25A of the liquid injection frame 25, and the contact surface 57 of the lower cooling member 56 comes into surface contact with the lower surface 25B of the liquid injection frame 25. More specifically, the upper and lower cooling members 56 are brought into contact with a portion of the outer surface of the liquid injection frame 25 that is aligned in a direction parallel to the lamination direction LD with respect to the outer liquid injection holes 27 and the inner liquid injection holes 28. Thereby, for example, the temperature of the electrolytic solution inside the liquid injection frame 25 decreases by about 5°C.

[0033] Subsequently, a depressurization process is performed. That is, the lid member is hermetically placed on the through hole of the chamber 41, and after placing it, the suction device 48 is operated. For example, the suction device 48 is operated until the pressure inside the chamber 41 reaches -90 KPa. As a result, a part of the gas inside the integrated object (for example, at least one of the internal space of the battery cell 12, the inner liquid injection hole 28, and the outer liquid injection hole 27) is sucked by the suction device 48 through the gap between the portion where the temporary fixing tape 60 of the cover member 30 is not provided and the liquid injection frame 25 and each outer liquid injection hole 27. That is, the depressurization process of the inside of the integrated object is executed.

[0034] Subsequently, a sealing process is performed. That is, as shown in FIG. 4, the heating part 52 of the heating device 50 heated to a predetermined temperature (for example, 140° C.) is moved from the initial position to the pushing position using the first actuator, and the heating surface 53 is brought into contact with the cover member 30. Further, using the first actuator, the heating part 52 is moved from the pushing position to the maximum pushing position behind the pushing position (see FIG. 5). The distance between the pushing position and the maximum pushing position is, for example, several millimeters. When the heating part 52 has moved to the maximum pushing position, the operation of the first actuator is stopped, and the heating part 52 is stopped at the maximum pushing position for a predetermined time. This predetermined time is, for example, several tens of seconds. As a result, a part (for example, the front part) of the liquid injection frame 25 is deformed by the heat transmitted from the heating part 52 to the liquid injection frame 25 via the cover member 30, and the end face 25C is heat-welded to the cover member 30. Thereby, the front end openings of the respective outer liquid injection holes 27 are sealed in an airtight state by the cover member 30.

[0035] Subsequently, a sealing completion process is performed. That is, when this predetermined time has elapsed, as shown in FIG. 6, the heating part 52 located at the maximum pushing position is returned to the initial position using the first actuator.

[0036] Subsequently, a decompression completion process is performed. That is, after the temperature of the heating part 52 (the temperature of the liquid injection frame 25) drops below the melting temperature of the liquid injection frame 25, the suction device 48 is stopped. As a result, the internal space of the chamber 41 communicates with the outer space of the chamber 41 via the pipe 47 and the suction device 48. That is, the air pressure in the internal space of the chamber 41 becomes equal to the air pressure in the outer space of the chamber 41.

[0037] Subsequently, a cooling completion process is performed. That is, the upper and lower cooling devices 55 located at the contact position are returned to the initial position using the second actuator. Thereby, the operation based on the vacuum sealing method using the vacuum sealing device 40 is completed. In other words, the battery 10 having three battery cells 12 is completed.

[0038] After that, after the operator removes the lid member from the chamber 41, the completed battery 10 can be taken out of the chamber 41 by using the opening of the chamber 41. Since the temporary fixing tape 60 is made of a material with high heat resistance, the temporary fixing tape 60 can be removed from the liquid injection frame 25 and the cover member 30.

[0039] As described above, the vacuum sealing method of this embodiment includes a step of bringing a pair of cooling members 56 into contact with the liquid injection frame 25. Therefore, when the liquid injection frame 25 is heated through the cover member 30 by the heating device 50 and the end face 25C of the liquid injection frame 25 is heat-sealed to the cover member 30, heat is hardly transferred to the electrolytic solution in the outer liquid injection holes 27 and the inner liquid injection holes 28 of the liquid injection frame 25. Therefore, the electrolytic solution generates gas, and deformation of the liquid injection frame 25 caused by an increase in the pressure due to this gas is suppressed.

[0040] Furthermore, in the vacuum sealing method of this embodiment, the upper and lower cooling members 56 are in contact with portions of the outer surface (upper surface 25A and lower surface 25B) of the liquid injection frame 25 that are arranged in a direction parallel to the lamination direction LD with respect to the outer liquid injection holes 27 and the inner liquid injection holes 28. Therefore, compared with the case where the upper and lower cooling members 56 are in contact with portions of the outer surface of the liquid injection frame 25 that are not arranged in a direction parallel to the lamination direction LD with respect to the outer liquid injection holes 27 and the inner liquid injection holes 28, the electrolytic solution in the outer liquid injection holes 27 and the inner liquid injection holes 28 is effectively cooled by the cooling members 56. That is, compared with the case where the upper and lower cooling members 56 are in contact with portions of the outer surface of the liquid injection frame 25 that are not arranged in a direction parallel to the lamination direction LD with respect to the outer liquid injection holes 27 and the inner liquid injection holes 28, the vacuum sealing method of this embodiment can more effectively suppress deformation of the liquid injection frame 25.

[0041] Furthermore, in the vacuum sealing method of this embodiment, gas can be sucked from the outer liquid injection holes 27, the inner liquid injection holes 28, etc. with the cover member 30 temporarily fixed to the liquid injection frame 25.

[0042] As described above, the vacuum sealing method of the battery according to the embodiment has been described, but these can be appropriately designed and changed within a range not departing from the gist of the present invention.

[0043] For example, the number of battery cells 12 that make up the battery 10 may be a plurality other than three or one cell.

[0044] The cross-sectional shape of the liquid injection hole provided in the liquid injection frame 25 may be constant throughout the front-rear direction (the longitudinal direction of the liquid injection hole).

[0045] The cooling device 55 may include one or three or more cooling members 56. When the cooling device 55 has one cooling member 56, the contact surface 57 of the cooling member 56 is brought into contact with the upper surface 25A or the lower surface 25B of the liquid injection frame 25. Also, even when the cooling device 55 has a plurality of cooling members 56, all the cooling members 56 may be brought into contact with the upper surface 25A or the lower surface 25B.

[0046] The cooling member 56 may be a Peltier element or an aluminum block.

[0047] The shape of the resin structure 20 may be different from the above shape.

[0048] The temporary fixing tape 60 may be made of a material with low heat resistance. In this case, in the sealing process, the temporary fixing tape 60 may be heat-welded to the liquid injection frame 25 and the cover member 30.

[0049] The battery cell 12 may include a plurality of electrodes and separators that do not include bipolar electrodes. That is, the battery 10 may be a battery of a type different from a bipolar type battery.

Description of Reference Numerals

[0050] 10 Battery (Bipolar Type Battery) 12 Battery Cell 15 Laminate 20 Resin Structure 25 Liquid Injection Frame 25A Upper Surface 25B Lower Surface 25C End Face 27 Outer Liquid Injection Hole (Liquid Injection Hole) 28 Inner Liquid Injection Hole (Liquid Injection Hole) 30 Cover Member (Resin Member) 56 Cooling member 60 Temporary fixing tape LD Laminating direction

Claims

1. A liquid injection step of injecting an electrolytic solution into the internal space of the laminate and the liquid injection hole through a liquid injection hole provided on an end surface of a resin-made liquid injection frame provided on an outer peripheral portion of a laminate having a plurality of electrodes; A covering step of covering the end surface with a resin member so as to cover the liquid injection hole; A cooling step of bringing a cooling member into contact with at least one of an upper surface and a lower surface of the liquid injection frame; A depressurization step of sucking gas from at least one of the internal space and the liquid injection hole through the liquid injection hole; and A sealing step of heating the liquid injection frame through the resin member to weld the end surface to the resin member. A method for depressurization and sealing of a battery having the above steps.

2. The cooling step is The method for depressurization and sealing of a battery according to claim 1, which is a step of bringing the cooling member into contact with a portion of the outer surface of the liquid injection frame that is aligned in the stacking direction of the liquid injection hole and the plurality of electrodes.

3. The method includes a step of temporarily fixing the resin member to the liquid injection frame using an adhesive temporary fixing tape, The depressurization step is a step of sucking gas from at least one of the internal space and the liquid injection hole through a gap between the resin member and the liquid injection frame in a state where the resin member is temporarily fixed to the liquid injection frame. The method for depressurization and sealing of a battery according to claim 1 or claim 2.

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