Method for manufacturing battery module and method for detecting impregnation state of electrolytic solution

Abstract

To provide a manufacturing method of a battery module capable of determining an impregnation state of an electrolyte to an electrode, and a detection method of the impregnation state of the electrolyte in the battery module.SOLUTION: A method of manufacturing a battery module according to the present disclosure is a method of manufacturing a battery module in which an electrode stack is accommodated in an internal space, the method including a step of starting injection of an electrolyte solution into the internal space, and a step of determining an impregnation state of the electrolyte solution with respect to the electrode stack based on a relative relationship of loads at a plurality of positions separated from each other in the battery module. With this configuration, it is possible to provide a method for manufacturing a battery module capable of determining the impregnation state of the electrolyte solution with respect to the electrode.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a battery module and a method for detecting the impregnation state of an electrolyte. [Background technology]

[0002] Patent Document 1 discloses a method for manufacturing a bipolar electricity storage device in which the pressure in the internal space in which the electrolyte is stored is reduced to promote impregnation of the electrolyte into the electrodes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-188536 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the manufacturing method of the bipolar type electricity storage device disclosed in Patent Document 1 cannot detect whether the electrodes have been sufficiently impregnated with the electrolyte. Therefore, activating the battery module (bipolar type electricity storage device) when the electrodes are not sufficiently impregnated with the electrolyte may cause battery failure.

[0005] The present disclosure has been made in view of the above circumstances, and provides a method for manufacturing a battery module that can determine the impregnation state of an electrolyte in electrodes, and a method for detecting the impregnation state of an electrolyte in the battery module. [Means for solving the problem]

[0006] A method for manufacturing a battery module according to one embodiment of the present disclosure includes: A manufacturing method of a battery module that houses an electrode stack in an internal space, comprising: starting to inject an electrolyte into the internal space; and determining a state of impregnation of the electrode stack with the electrolyte based on a relative relationship between loads at a plurality of positions spaced apart from one another in the battery module.

[0007] A method for detecting an impregnation state of an electrolyte according to one embodiment of the present disclosure includes: A method for detecting an impregnation state of an electrolyte solution in an electrode stack in a battery module that houses the electrode stack in an internal space, comprising: In the battery module, the state of impregnation of the electrode stack with the electrolyte is detected based on the relative relationship of the loads at a plurality of positions spaced apart from one another. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a method for manufacturing a battery module that can determine the impregnation state of an electrolyte in an electrode, and a method for detecting the impregnation state of an electrolyte in the battery module. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic perspective view of a battery module according to an embodiment of the present disclosure. [Figure 2] FIG. 1 is a cross-sectional view of a battery module according to an embodiment of the present disclosure. [Figure 3] FIG. 1 is a block diagram of a detector according to an embodiment of the present disclosure. [Figure 4] 10 is a graph showing the time transition of a load in a battery module according to an embodiment of the present disclosure. [Figure 5] 1 is a flowchart illustrating a method for manufacturing a battery module according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, specific embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present disclosure is not limited to the following embodiments. In addition, the following description and drawings have been simplified appropriately for clarity of explanation.

[0011] <Battery module configuration> Fig. 1 is a schematic perspective view of a battery module according to an embodiment of the present disclosure, and Fig. 2 is a cross-sectional view of the battery module according to an embodiment of the present disclosure. The right-handed xyz Cartesian coordinate system shown in Figures 1 and 2 is for the sake of convenience in showing the positional relationships of the components. In Figures 1 and 2, the positive z-axis direction is vertically upward, and the xy plane is the horizontal plane, which is common to all the figures.

[0012] The battery module 1 includes a positive electrode active material layer 11, a negative electrode active material layer 12, a current collector 13, a separator 14, and a battery container 15. In the battery module 1 shown in FIG. 1, the positive electrode active material layer 11, the negative electrode active material layer 12, the current collector 13, and the separator 14 are stacked to form an electrode stack as a whole. The battery container 15 has an internal space V therein and is equipped with a liquid injection port 16 that connects the internal space V to the outside. Additionally, an electrolyte (not shown) is accommodated in the internal space V.

[0013] The battery module 1 is a secondary battery such as a lithium-ion secondary battery or a nickel-metal hydride battery. In this embodiment, the battery module 1 is exemplified as a lithium-ion secondary battery, but the type of battery is not limited thereto. Furthermore, the number of stacked positive electrode active material layers 11, negative electrode active material layers 12, current collectors 13, and separators 14 in the battery module 1 is not particularly limited and is determined appropriately depending on the application.

[0014] The positive electrode active material layer 11 is formed on the surface of a current collector 13. The positive electrode active material layer 11 faces the negative electrode active material layer 12 with a separator 14 sandwiched therebetween. The positive electrode active material layer 11 contains a positive electrode active material and may further contain an electrolyte, a conductive additive, and a binder, as desired. Examples of the positive electrode active material include lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide.

[0015] The negative electrode active material layer 12 is formed on the surface of a current collector 13. The negative electrode active material layer 12 faces the positive electrode active material layer 11 with a separator 14 sandwiched therebetween. The negative electrode active material layer 12 contains a negative electrode active material and may further contain an electrolyte, a conductive additive, and a binder, as desired. Examples of the negative electrode active material include carbon, graphite, and lithium titanate.

[0016] The current collector 13 has one or more of a positive electrode active material layer 11 and a negative electrode active material layer 12 formed on its surface. The current collector 13 faces the separator 14 with the positive electrode active material layer 11 or the negative electrode active material layer 12 sandwiched therebetween. Examples of materials for the current collector 13 include aluminum and copper. Note that a portion of the current collector 13 may be extended to the outside of the battery container 15 to enable connection to an external terminal.

[0017] The separator 14 prevents a short circuit between the positive electrode active material layer 11 and the negative electrode active material layer 12. The separator 14 is disposed between the positive electrode active material layer 11 and the negative electrode active material layer 12. The separator 14 is a porous film made of, for example, polyethylene or polypropylene.

[0018] The battery container 15 holds therein the positive electrode active material layer 11, the negative electrode active material layer 12, the current collector 13, the separator 14, and the electrolyte. The battery container 15 is made of, for example, a metal can or a laminate film made by bonding a metal foil and a resin such as polypropylene. Although FIG. 1 shows the battery container 15 in a flat plate shape, the shape of the battery container 15 is not particularly limited.

[0019] The liquid filling port 16 is formed in the wall surface of the battery container 15 for filling the electrolyte into the internal space V. The liquid filling port 16 connects the internal space V with the outside. Here, the plurality of liquid filling ports 16 are preferably formed on one side surface of the battery module 1 as shown in Fig. 1. With this configuration, it is possible to determine the impregnation state of the electrolyte in the battery module 1 even when the electrolyte is poured from the vicinity of the end of the battery module 1 through the plurality of liquid filling ports 16. Note that, although the plurality of liquid filling ports 16 are formed on a surface parallel to the yz plane in Fig. 1, they may also be formed on a surface parallel to the xz plane.

[0020] The internal space V is formed as a space surrounded by the current collector 13 and the battery container 15. The internal space V is connected to the outside via a liquid inlet 16, and an electrolyte solution is poured into the internal space V. Examples of the electrolyte solution to be poured include those obtained by dissolving lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, or the like in a solvent such as ethylene carbonate, dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate.

[0021] 1, the electrode laminate composed of the positive electrode active material layer 11, the negative electrode active material layer 12, the current collector 13, and the separator 14 is stacked in the z-axis direction, but the stacking direction of the electrode laminate may be the x-axis direction or the y-axis direction and is not particularly limited. For example, when the stacking direction is the x-axis direction, multiple internal spaces V are formed side by side in the x-axis direction, and therefore multiple liquid injection ports 16 are formed in a plane parallel to the xz plane or a plane parallel to the xy plane in accordance with the positions of the internal spaces V.

[0022] <Detector configuration> Fig. 3 is a block diagram of a detector according to an embodiment of the present disclosure. The detector 2 shown in Fig. 3 measures loads at multiple positions spaced apart from one another in the xy plane on the battery module 1. In addition, the detector 2 determines the impregnation state of the electrolyte in the battery module 1 based on the measured load. The detector 2 includes a measurement unit 21, a control unit 22, and a determination unit 23. Note that while Fig. 3 depicts only one detector 2, multiple detectors 2 may be used to measure the load on the battery module 1 and determine the impregnation state of the electrolyte.

[0023] The measuring unit 21 is connected to the control unit 22 and the determination unit 23. The measuring unit 21 measures the load of the battery module 1 at a certain position. Here, the means for measuring the load by the measuring unit 21 includes, for example, a method of measuring by placing the battery module 1 on a table on which the measuring unit 21 is placed, a method of suspending the battery module 1 by a plurality of measuring units 21, and the like, but is not particularly limited thereto.

[0024] 1, one or more measuring units 21 are preferably disposed on each of the side of the liquid inlet 16 and the opposite side of the liquid inlet 16. By disposing measuring units 21 at multiple positions at different distances from the liquid inlet 16, the accuracy of determining the impregnation state of the electrolyte in the battery module 1 is improved.

[0025] 3 includes two measuring units 21, the detector 2 may include three or more measuring units 21, or may include only one measuring unit 21. For example, if the detector 2 includes four measuring units 21, arranging the measuring units 21 at the four corners of the plane of the battery module 1 will further improve the accuracy of determining the impregnation state of the electrolyte in the battery module 1 compared to when only two measuring units 21 are arranged. Furthermore, even if the detector 2 includes only one measuring unit 21, it is possible to determine the impregnation state of the electrolyte in the battery module 1 by measuring the load at multiple positions using multiple detectors 2.

[0026] The control unit 22 is connected to the measurement unit 21 and the determination unit 23. The control unit 22 executes various functions of the detector 2 based on the load of the battery module 1 measured by the measurement unit 21 and the impregnation state of the electrolyte in the battery module 1 determined by the determination unit 23. The control unit 22 is configured by, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a working memory, and a non-volatile storage device storing a control program. The control unit 22 can also be configured to include an IC (Integrated Circuit).

[0027] The determination unit 23 is connected to the measurement unit 21 and the control unit 22. Furthermore, the determination unit 23 determines the impregnation state of the electrolyte in the battery module 1 based on the load of the battery module 1 measured by the measurement unit 21. Note that the determination unit 23 may convert the load measured by the measurement unit 21 into other parameters such as weight, pressure, and a change in electrical resistance associated with displacement or strain due to the weight, and use the converted value as load information to determine the impregnation state of the electrolyte.

[0028] 4 is a graph showing the change over time in the load within the battery module according to the embodiment of the present disclosure. The solid line shows the change over time in the load of the battery module 1 on the side of the liquid inlet 16, and the dashed line shows the change over time in the load of the battery module 1 on the opposite side of the liquid inlet 16.

[0029] The determination unit 23 determines the state of impregnation of the electrode stack with the electrolyte based on the relative relationship of the loads at multiple positions spaced apart from each other. Specifically, as shown in FIG. 4 , the determination unit 23 calculates the difference between the load measured by the measurement unit 21 located on the side of the liquid inlet 16 and the load measured by the measurement unit 21 located on the opposite side of the liquid inlet 16. If the difference is below a threshold, the determination unit 23 determines that impregnation of the battery module 1 with the electrolyte is complete. However, the impregnation completion determination method is not limited to this. For example, a determination method may be used in which more than two measurement units 21 measure the load of the battery module 1 and the difference between the maximum and minimum values ​​of the measured loads is below a threshold. Furthermore, the completion of impregnation of the electrolyte may be determined using other parameters, such as weight, pressure, or a change in electrical resistance due to displacement or strain caused by weight, instead of load. The completion of impregnation of the electrolyte may also be determined using a combination of multiple parameters.

[0030] As described above, the detector according to the embodiment of the present disclosure measures the load of the battery module at multiple positions spaced apart from one another, thereby determining the state of electrolyte impregnation in the battery module and being able to determine when electrolyte impregnation is complete.

[0031] <Battery module manufacturing method> Next, a method for manufacturing a battery module according to an embodiment of the present disclosure and a method for detecting the impregnation state of the electrolyte in the battery module will be described with reference to Fig. 5. Fig. 5 is a flowchart showing the method for manufacturing a battery module according to an embodiment of the present disclosure.

[0032] First, the electrolyte is injected into the battery module 1 through the injection port 16 (step S1). For example, the injection method involves reducing the pressure inside the battery module 1 in advance, and then connecting a pipe through which the electrolyte flows and a container for holding the electrolyte to the injection port 16. This generates a pressure difference between the inside and outside of the battery module 1, and this pressure difference causes the electrolyte to be sucked into the battery module 1 and injected. However, the injection method is not particularly limited, and other methods may be used, such as a method of directly injecting the electrolyte through a pipe using a pump or the like. Furthermore, the amount and speed of the electrolyte to be injected are not particularly limited.

[0033] Subsequently, in step S1, a predetermined amount of electrolyte is injected into the battery module 1, and then the injection is stopped (step S2).

[0034] Next, the detector 2 measures the load at a plurality of positions spaced apart from each other on the battery module 1 (step S3). In step S3, for example, the detector 2 measures the load of the battery module 1 at two positions, one on the side of the battery module 1 facing the liquid injection port 16 and the other on the opposite side of the liquid injection port 16. Note that in FIG. 5, step S3 in which the detector 2 measures the load of the battery module 1 is provided downstream of step S2 in which the liquid injection is stopped, but step S3 may also be provided upstream of step S2. In other words, the detector 2 may measure the load of the battery module 1 during the liquid injection.

[0035] Next, using the load measured in step S3, the detector 2 determines the state of electrolyte impregnation in the battery module 1 (step S4). In step S4, for example, the detector 2 calculates the difference between the loads measured at two positions on the battery module 1, one on the side of the liquid inlet 16 and the other on the opposite side of the liquid inlet 16, and determines whether the difference is below a threshold value. However, as described above, the method for determining completion of electrolyte impregnation is not limited to this.

[0036] If the difference in load measured in step S3 is below the threshold value (YES in step S4), it is determined that impregnation of the electrolyte in the battery module 1 is complete, and the process ends. On the other hand, if the difference in load is not below the threshold value (NO in step S4), the process returns to step S3, and after a predetermined time, the load values ​​of the battery module 1 are measured again on the side of the battery module 1 opposite to the liquid inlet 16. However, there is no particular limitation on the time interval between measuring the load of the battery module 1 and measuring the load of the battery module 1 again.

[0037] As described above, the manufacturing method of a battery module according to an embodiment of the present disclosure detects the state of electrolyte impregnation in the battery module by measuring the load of the battery module at multiple positions and determines whether the impregnation of the electrolyte has been completed. This provides a manufacturing method of a battery module that can determine the state of electrolyte impregnation of the electrodes. [Explanation of symbols]

[0038] 1 Battery Module 11 Cathode active material layer 12 Negative electrode active material layer 13 Current collector 14 Separator 15 Battery container 16 Filling port 2 Detectors 21 Measurement section 22 Control Unit 23 Judgment section V interior space

Claims

1. A manufacturing method of a battery module that houses an electrode stack in an internal space, comprising: starting to inject an electrolyte into the internal space; and determining an impregnation state of the electrolyte solution in the electrode stack based on a relative relationship between loads at a plurality of positions spaced apart from one another in the battery module. A method for manufacturing a battery module.

2. the battery module has a flat plate shape, In the step of measuring the load, the load is measured at a plurality of positions spaced apart from each other on a plane of the battery module. The method for manufacturing the battery module according to claim 1 .

3. In the step of starting the injection of the electrolyte, the electrolyte is injected from a vicinity of an end of the battery module. The method for manufacturing the battery module according to claim 2 .

4. When it is determined that the impregnation state of the electrolyte has reached a predetermined impregnation state, the injection is stopped. The method for manufacturing the battery module according to any one of claims 1 to 3.

5. A method for detecting an impregnation state of an electrolyte solution in an electrode stack in a battery module that houses the electrode stack in an internal space, comprising: In the battery module, the impregnation state of the electrolyte solution in the electrode stack is detected based on a relative relationship between loads at a plurality of positions spaced apart from each other. A method for detecting the state of impregnation of the electrode stack with an electrolyte.

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