Manufacturing method of power storage device

Abstract

To provide a manufacturing method of a power storage device, capable of reducing a manufacturing processing time.SOLUTION: A manufacturing method of a power storage device, according to the present invention, is a manufacturing method of a power storage device, having one or a plurality of power storage modules 1 having an electrode lamination body 11 to which a plurality of electrodes is laminated, that comprises: a preparation compression step (a step S102) of compressing the power storage modules 1 via an elastic body 2 by a preparation compression; a main compression step (a step S103) of compressing the power storage modules 1 via the elastic body 2 by a main compression that is lower than the preparation compression after the preparation compression step S102; and a measurement step (a step S104) of measuring a distance to a lamination direction in a lamination structure containing at least the power storage modules 1 and the elastic body 2 after the main compression step (the step S103).SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a power storage device.

Background Art

[0002] As a type of power storage device, there is a power storage device including one or more power storage modules each including a laminate in which a plurality of electrodes are laminated. The power storage module includes, for example, a laminate in which a plurality of bipolar electrodes are laminated via a separator. In some of the plurality of steps for manufacturing such a power storage device, it is necessary to perform various operations while maintaining contact between the bipolar electrodes. For example, Patent Document 1 discloses a method of performing a predetermined manufacturing process while maintaining a restraint pressure applied to a power storage module. In this document, a restraint pressure is applied to the power storage module via an elastic body and a restraint body. Then, a predetermined manufacturing process is executed while maintaining the applied restraint pressure by a restraint jig.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Regarding the method for manufacturing a power storage device disclosed in Patent Document 1, the inventors have found the following problems. In order to maintain a state in which a desired restraint pressure is applied to the power storage module by a restraint jig, for example, in a state where a desired restraint pressure is applied by a pressurizing device, it is necessary to measure the thickness of the elastic body sandwiched between the restraint bodies and the power storage module and fix it with the restraint jig in order to maintain the thickness. The inventors have found through experiments that in the measurement process, as the restraint pressure is applied, the thickness of the elastic body gradually decreases, and the thicknesses of the elastic body and the power storage module change. Thus, in a state where the thickness of the elastic body is gradually changing, the thicknesses of the elastic body and the power storage module for generating a desired restraint pressure cannot be accurately measured. Therefore, it is necessary to wait until the change in the thickness of the elastic body with time disappears. As a result, the time for the measurement process becomes long, and the manufacturing process time of the power storage device also becomes long.

[0005] The present invention has been made to solve such problems, and an object thereof is to provide a method for manufacturing a power storage device capable of shortening the manufacturing process time.

Means for Solving the Problems

[0006] A method for manufacturing a power storage device according to the present invention is a method for manufacturing a power storage device including one or more power storage modules each including an electrode laminate in which a plurality of electrodes are laminated, the method including a preliminary pressurization step of pressurizing the power storage module via an elastic body by preliminary pressurization, a main pressurization step of pressurizing the power storage module via the elastic body by main pressurization lower than the preliminary pressurization after the preliminary pressurization step, and a measurement step of measuring at least a distance in a lamination direction in a laminated structure including the power storage module and the elastic body after the main pressurization step.

[0007] Here, it is preferable that the elastic body contains a foamed material. In the method for manufacturing a power storage device according to the present invention, in such a configuration, it is possible to particularly suppress a change in the thickness of the elastic body over time.

[0008] Also, it is preferable that the elastic body is a pair of members sandwiching the power storage module. With such a configuration, pressure can be applied to the power storage module more uniformly.

[0009] Furthermore, it is preferable to include a restraining step of fixing the position of a restraining member that restrains the laminated structure with a restraining jig after the measuring step. With such a configuration, a predetermined manufacturing process can be executed while maintaining the restraining pressure applied to the power storage module.

[0010] A method for manufacturing a power storage device according to the present invention is a method for manufacturing a power storage device including one or more power storage modules each including a laminate in which a plurality of electrodes are laminated, and includes a preliminary pressurization step of pressurizing the power storage module via an elastic body by preliminary pressurization, a main pressurization step of pressurizing the power storage module via the elastic body by main pressurization that is lower than the preliminary pressurization after the preliminary pressurization step, and a restraining step of fixing the power storage module and the elastic body at a stage where the volume change of the elastic body converges in a state pressurized by the main pressurization in the main pressurization step. With such a configuration, the restraining step can be executed without executing the measuring step after the main pressurization step. Also in this case, it is possible to maintain a state in which a desired restraining pressure is continuously applied to the power storage module in a restrained state by a restraining jig.

Advantages of the Invention

[0011] According to the present invention, it is possible to provide a method for manufacturing a power storage device capable of shortening the manufacturing process time.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0013] Embodiment 1 Hereinafter, with reference to the drawings, a method for manufacturing a power storage device according to Embodiment 1 will be described.

[0014] A power storage device including one or more power storage modules is manufactured through a plurality of steps. Among the plurality of steps, for example, in the liquid injection step, the initial charging step, and the high-temperature aging step, various operations may be performed with the power storage modules incorporated in the power storage device being restrained in the stacking direction. In steps other than these liquid injection step, initial charging step, and high-temperature aging step, operations may also be performed with the power storage modules restrained as necessary. Here, with reference to FIG. 1, the restraint state of the power storage module will be described. FIG. 1 is a schematic diagram showing the configuration in a state where the power storage module 1 is restrained. In the state where the power storage module is restrained, as shown in FIG. 1, a pair of elastic bodies 2 and a restraint body 3 are arranged so as to sandwich the power storage module 1, and further, from the side surface side, the positions of the power storage module 1, the elastic body 2, and the restraint body 3 in the stacking direction are fixed by the restraint jig 4.

[0015] The power storage module 1 is a plate-shaped non-aqueous battery, for example, a bipolar battery including a bipolar electrode 14 described later. The power storage module 1 to be constrained is not limited to one, and there may be a plurality of them. When constraining a plurality of power storage modules 1, the power storage modules 1 are laminated so that their main surfaces are in contact with each other. The internal configuration of the power storage module 1 will be described in detail later.

[0016] The elastic body 2 has elasticity. By having elasticity, the elastic body 2 can apply a desired constraint pressure to the power storage module 1 in a state where the positions of the power storage module 1, the elastic body 2, and the constraining body 3 in the lamination direction are fixed. In the first embodiment, a pair of elastic bodies 2 are arranged so as to sandwich the power storage module 1 from both sides. However, the elastic body 2 may be arranged only on one side of the power storage module 1. The elastic body 2 further has electrical insulation properties and insulates between the power storage module 1 and the constraining body 3. The elastic body 2 includes, for example, a foam using a foaming material such as urethane or EPDM (ethylene propylene diene rubber). However, the entire elastic body 2 does not have to be a foam, and a part of the elastic body 2 may be a foam. The foam is a structure containing gas inside, and the contained gas is discharged to the outside when pressure is applied from the outside. The foam is, for example, a porous body composed of a synthetic resin having elasticity. In the present embodiment, a suitable elastic body 2 is such that when a pressure exceeding the constraint pressure is applied, the internal gas is discharged to the outside and the volume decreases, and then in a state where the constraint pressure is applied, the volume basically does not decrease any further and increases by restoring. When using a foam as the elastic body 2, the foaming rate can be changed depending on the location, and a hardness distribution may be provided in the in-plane direction of the elastic body 2. When the power storage module 1 is constrained by the constraining jig 4, there may be a difference in the distribution of the constraint pressure applied to the power storage module 1 due to the difference in the distance from the constraining jig 4. Therefore, by providing a hardness distribution in the in-plane direction of the elastic body 2, the difference in the constraint pressure distribution due to the difference in the distance from the constraining jig 4 can be alleviated. Therefore, a uniform distribution of the constraint pressure can be applied to the power storage module 1, and the separation between the bipolar electrodes can be preferably suppressed.

[0017] The restraining body 3 is arranged to sandwich the power storage module 1 and the elastic body 2 from both sides. The restraining body 3 is a plate-shaped rigid member. The restraining body 3 is made of a material such as metal or synthetic resin. By applying pressure to the restraining body 3 in the stacking direction of the electrodes using a pressing device such as a press, the power storage module 1 is pressurized. It is preferable that the restraining body 3 does not deform due to the pressurization of the power storage module 1.

[0018] Note that the contact area between the restraining body 3 and the elastic body 2 is preferably larger than the contact area between the power storage module 1 and the elastic body 2. Even if the position of the power storage module moves due to pressurization, a uniform restraining pressure can be applied to the power storage module 1. Also, typically, the elastic body 2 and the restraining body 3 are constituted by separate bodies, but they may be integrated.

[0019] The restraining jig 4 is used to maintain the restraining pressure on the power storage module 1 and to fix the distance in the stacking direction in the stacked structure including the power storage module 1 and the elastic body 2 after being pressurized by the restraining body 3. That is, the restraining jig 4 fixes the positions of the power storage module 1, the elastic body 2, and the restraining body 3 in the stacking direction. The restraining jig 4 can fix the distance in the stacking direction in the stacked structure including the power storage module 1 and the elastic body 2 to an arbitrary distance by a mechanical mechanism or an electrical mechanism. The restraining jig 4 may be constituted, for example, by including bolts and nuts. Thereby, for example, a bolt is inserted from an insertion hole provided in one restraining body 3 toward an insertion hole provided in the other restraining body 3, and a nut is screwed onto the tip portion of the bolt protruding from the insertion hole provided in the other restraining body 3.

[0020] The distance in the stacking direction in the stacked structure including the power storage module 1 and the elastic body 2 is a distance that generates a desired restraint pressure on the power storage module 1. Specifically, in a state where pressure is applied to the power storage module 1 using a pressure device such as a press, it is detected by a pressure sensor or the like that the applied pressure is a desired value or range, and the distance at that time is measured to determine it. The distance in the stacking direction in the stacked structure including the power storage module 1 and the elastic body 2 is measured by, for example, a distance sensor or a distance meter (not shown).

[0021] When the position in the stacking direction is fixed by the restraint jig 4, due to the elasticity of the elastic body 2, the restraint pressure on the power storage module 1 can be maintained without continuously operating a pressure device such as a press. Therefore, according to the first embodiment, in a state where a restraint pressure is applied to the power storage module 1, for example, manufacturing processes such as a liquid injection process, a first charge process, and a high-temperature aging process can be carried out.

[0022] Next, with reference to FIG. 2, the power storage module included in the power storage device according to the first embodiment will be described. FIG. 2 is a schematic cross-sectional view showing the internal configuration of the power storage module. The power storage module 1 includes an electrode laminate 11 including a plurality of electrodes and a sealing body 12 that seals the electrode laminate 11.

[0023] In the electrode laminate 11, a plurality of bipolar electrodes 14 are laminated via a separator 13. The bipolar electrode 14 is an electrode including an electrode plate 15, a positive electrode 16, and a negative electrode 17. A negative terminal electrode 18 is disposed at the first end of the electrode laminate 11, and a positive terminal electrode 19 is disposed at the second end opposite to the first end of the electrode laminate 11. The negative terminal electrode 18 is an electrode including the electrode plate 15 and the negative electrode 17. The positive terminal electrode 19 is an electrode including the electrode plate 15 and the positive electrode 16. The plurality of bipolar electrodes 14 are disposed between the negative terminal electrode 18 and the positive terminal electrode 19 in the stacking direction.

[0024] The sealing body 12 is provided so as to surround the side surface of the electrode laminate 11. Examples of the material used for the sealing body 12 include polypropylene, polyphenylene sulfide, or modified polyphenylene ether.

[0025] Subsequently, a method for manufacturing the power storage device according to Embodiment 1 will be described. FIG. 3 is a flowchart of the method for manufacturing the power storage device according to Embodiment 1.

[0026] First, in a lamination step, one or a plurality of power storage modules 1 are sandwiched between a pair of elastic bodies 2, and further, the power storage module 1 and the elastic bodies 2 are sandwiched between a pair of restraining bodies 3 (step S101). At this time, the power storage module 1, the elastic bodies 2, and the restraining bodies 3 may be simultaneously overlapped, or may be stacked in order from the member located below.

[0027] Next, a preliminary pressurization step is performed (step S102). In the preliminary pressurization step, for example, a pressurizing device such as a press machine is used to apply a predetermined pressure to the restraining body 3 (hereinafter referred to as preliminary pressurization), and the power storage module 1 is pressurized. Here, the value of the pressure applied to the power storage module 1 by the preliminary pressurization (pre-press) is set higher than the pressure value of the restraining pressure applied in the next step S103. Therefore, the elastic body 2 in the state where the preliminary pressurization is applied is elastically deformed and has a reduced thickness compared to the state where the restraining pressure is applied. Here, when the elastic body 2 contains a foam, a part of the gas in the foam is discharged to the outside by the preliminary pressurization.

[0028] Next, the main pressing process is executed (step S103). In this main pressing process, the pressure is reduced to the confinement pressure to be applied to the power storage module 1, and the power storage module 1 is pressed by the confinement pressure. Specifically, the pressing device detects the pressure value applied to the confinement body 3 and controls the applied pressure so that the pressure value reaches a predetermined confinement pressure value or range. At this time, the elastic body 2 will recover from the state of being elastically deformed and having a reduced thickness due to the preliminary pressing, that is, a state of being crushed to some extent. Therefore, the outer shape of the elastic body 2 changes in the direction of increasing thickness, that is, the direction of expanding the confinement body 3, and the change amount converges to a value equal to or less than a predetermined value after a predetermined time has elapsed. At this time, after the preliminary pressing, by reducing the pressure to a confinement pressure lower than the preliminary pressing, the time until the change amount of the thickness of the elastic body 2 finally converges can be made shorter than when pressing from a state where no preliminary pressing is performed and no pressure is applied to the confinement pressure.

[0029] Next, the measurement process is executed (step S104). In the measurement process, with the power storage module 1 being pressed by the confinement pressure, the distance in the stacking direction in the stacked structure including the power storage module 1 and the elastic body 2 is measured by measuring means (not shown).

[0030] Finally, the confinement process is executed (step S105). In the confinement process, the confinement jig 4 is adjusted so as to maintain the measured distance in the stacking direction in the stacked structure including the power storage module 1 and the elastic body 2, and the power storage module 1 is confined. In the present embodiment, the confinement process is executed while the confinement pressure is applied. However, once the confinement pressure is released, it may be confined so as to be the distance measured by the measurement process.

[0031] By confining the power storage module 1 with the confinement jig 4, it can be easily transported to the next manufacturing process while maintaining the state where the power storage module 1 is pressed by the confinement pressure.

[0032] Thus, in this embodiment, the preliminary pressurization in the preliminary pressurization step (step S102) is at a higher pressure than the restraint pressure in the main pressurization step (step S103). By applying a pressure greater than the restraint pressure in the preliminary pressurization step, the elastic body 2 can be pre-compressed in advance, and the amount of change in the thickness of the elastic body 2 over time can be suppressed. Therefore, the measurement time of the distance in the stacking direction in the stacked structure including the power storage module 1 and the elastic body 2 in the measurement step (step S104) can be shortened.

[0033] Hereinafter, examples of the manufacturing method of the power storage device according to Embodiment 1 will be described. FIG. 4 is a graph showing the relationship between the pressure (surface pressure) applied to the restraint body 3 and the stroke amount of the pressurizing device in the examples and comparative examples. FIG. 5 is a graph showing the change in the stroke amount of the pressurizing device with respect to time change in the examples and comparative examples. In the example, after applying preliminary pressurization in the preliminary pressurization step (step S102), the pressure is reduced to the restraint pressure in the main pressurization step (step S103). On the other hand, in the comparative example, the main pressurization step (step S103) was carried out without carrying out the preliminary pressurization step (step S102), and the same restraint pressure as in the example was applied. This time, the preliminary pressurization was 200 KPa and the restraint pressure was 100 KPa. The stroke amount is the amount by which the pressurizing device pushes the restraint body 3 in the stacking direction of the electrodes in order to apply pressure to the power storage module 1.

[0034] From FIG. 4, in the comparative example, the stroke amount changes while the restraint pressure is being applied in the main pressurization step (step S103). Also, from FIG. 5, the stroke amount increases as time elapses. In other words, the distance in the stacking direction in the stacked structure including the power storage module 1 and the elastic body 2 decreases as time passes. This is presumably because the elastic body 2 is compressed over time and its thickness decreases.

[0035] On the other hand, regarding the examples, as shown in FIG. 4, the change in the stroke amount while applying the restraint pressure in this pressurization step (step S103) is smaller than that of the comparative example. Also, as shown in FIG. 5, the increase amount of the stroke amount with respect to the passage of time is also smaller in the example than in the comparative example. Therefore, in the example, it is possible to suppress the decrease in the distance in the stacking direction in the stacked structure including the power storage module 1 and the elastic body 2 while applying the restraint pressure. This is presumably because the elastic body 2 was sufficiently compressed in advance by applying a pre-pressurization higher than the restraint pressure in the pre-pressurization step (step S102). From this result, it can be confirmed that by applying a pressure higher than the restraint pressure before applying the restraint pressure, the time change in the thickness of the elastic body while applying the restraint pressure can be suppressed.

[0036] Note that the present invention is not limited to the above-described embodiments, and can be appropriately modified without departing from the gist. For example, in the above-described embodiment, the measurement step (step S104) is executed after the main pressurization step (step S103), but not limited thereto, after the main pressurization step (step S103), the restraint step (step S105) may be executed without executing the measurement step (step S104). In this case, in the restraint step (step S105), when the volume change of the elastic body 2 has converged in the state pressurized by the main pressurization in the main pressurization step, the position of the restraint body 3 with respect to the power storage module 1 and the elastic body 2 is fixed. By such a method as well, it is possible to maintain the state in which the desired restraint pressure is continuously applied to the power storage module 1 in the restrained state by the restraint jig 4.

Explanation of Reference Numerals

[0037] 1 Power storage module 2 Elastic body 3 Restraint body 4 Restraint jig 11 Electrode laminate

Claims

1. A method for manufacturing an energy storage device including one or more energy storage modules each including an electrode laminate in which a plurality of electrodes are laminated, the method comprising: a pre-pressurization step of pressurizing the energy storage module via an elastic body by pre-pressurization; a main pressurization step of pressurizing the energy storage module via the elastic body by main pressurization that is lower than the pre-pressurization, after the pre-pressurization step; a measurement step of measuring a distance in a lamination direction in a laminated structure including at least the energy storage module and the elastic body, after the main pressurization step; A method for manufacturing an energy storage device comprising the above steps.

2. The elastic body includes a foamed material. A method for manufacturing an energy storage device according to Claim 1.

3. The elastic body is a pair of members sandwiching the energy storage module. A method for manufacturing an energy storage device according to Claim 1 or 2.

4. After the measurement step, the method further comprises a restraint step of fixing the position of a restraint body that restrains the laminated structure with a restraint jig. A method for manufacturing an energy storage device according to Claim 1 or 2.

5. A method for manufacturing an energy storage device including one or more energy storage modules each including a laminate in which a plurality of electrodes are laminated, the method comprising: a pre-pressurization step of pressurizing the energy storage module via an elastic body by pre-pressurization; a main pressurization step of pressurizing the energy storage module via the elastic body by main pressurization that is lower than the pre-pressurization, after the pre-pressurization step; a restraint step of fixing the energy storage module and the elastic body at a stage where a volume change of the elastic body converges in a state pressurized by the main pressurization in the main pressurization step; A method for manufacturing an energy storage device comprising the above steps.

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