JP2023040697A - Manufacturing method of power storage module - Google Patents

Abstract

To improve the non-defective rate of a power storage module.SOLUTION: A manufacturing method of a power storage unit includes an arrangement step S1, a preheating step S4, a welding step S6, and a stacking step S10. In the preheating step S4, a pre-welding resin portion placed in the arrangement step S1 is pressed against the main surface of a current collector with preheating pressure, and the resin temperature which is the temperature of the resin portion is maintained at a softening point or higher and lower than a melting point to preheat the resin portion. In the welding step S6, the preheated resin portion is pressed against the current collector with the welding pressure and the temperature of the resin portion is kept the melting point or higher to weld the resin portion to the main surface to manufacture an electrode unit. In the stacking step S10, the power storage module is manufactured by stacking the electrode units that have undergone the welding step S6. The preheating pressure is less than the welding pressure.SELECTED DRAWING: Figure 5

Description

The present invention relates to a method for manufacturing an electric storage module.

The power storage module described in Patent Literature 1 includes a plurality of electrode units. The electrode unit includes a current collector that is a metal foil, an active material layer provided on the main surface of the current collector, and a resin portion that is welded to the main surface of the current collector so as to surround the active material layer. , provided. The resin portion is interposed between the adjacent electrode units to ensure insulation between the adjacent electrode units. The welding of the resin portion to the current collector is performed by disposing the resin portion on the main surface of the current collector and welding the disposed resin portion.

JP 2020-107486 A

By the way, the resin portion is deformed by thermal contraction due to cooling after welding. Thermal contraction of the resin portion causes deformation of the current collector to which the resin portion is welded. The degree of thermal shrinkage of the resin portion varies depending on the residual stress of the resin portion that exists before being welded to the current collector. Therefore, variations in the residual stress inherent in the resin portion cause unintended deformation of the resin portion, such as bending and waviness. A current collector used in the electrode unit is generally a thin metal foil. Therefore, such unintended deformation may damage the current collector, which is a metal foil. As a result, there is a risk that the percentage of non-defective power storage modules will decrease.

A method for manufacturing an electric storage module that solves the above problems includes: a current collector that is a metal foil; an active material layer provided on the main surface of the current collector; A method of manufacturing an electricity storage module including a plurality of electrode units each having a welded resin portion, the method comprising: placing the resin portion before welding on the main surface; A preheating step of preheating the resin portion by pressing the resin portion against the electric body with preheating pressure and maintaining the temperature of the resin portion at a softening point or more and less than the melting point of the resin portion; a welding step of manufacturing the electrode unit by welding the resin portion to the main surface by pressing the resin portion against the current collector with a welding pressure and maintaining the temperature of the resin portion at the melting point or higher; and a stacking step of manufacturing the electricity storage module by stacking the electrode units that have undergone the welding step, wherein the preheating pressure is lower than the welding pressure.

According to this, an electrode unit is manufactured through an arrangement process, a preheating process, and a welding process. A power storage module is manufactured by stacking a plurality of such electrode units through a stacking process.

Here, in this configuration, the preheating step is performed before the resin portion is welded to the main surface of the current collector in the welding step. In the preheating step, the temperature of the resin portion is kept above the softening point of the resin portion and below the melting point of the resin portion, thereby suppressing welding of the resin portion to the current collector and promoting softening of the resin portion. The softening of the resin portion relaxes the residual stress of the resin portion. As a result, variations in the residual stress of the resin portion are reduced in the stage prior to the welding process.

On the other hand, along with the relaxation of the residual stress, unintended deformation of the resin portion such as bending and waviness may occur. Therefore, in the preheating step, the resin portion is pressed against the main surface of the current collector with preheating pressure. Thereby, when the residual stress is relaxed in the preheating step, deformation of the resin portion in a direction perpendicular to the main surface of the current collector can be restricted. Furthermore, by making the preheating pressure smaller than the welding pressure, the relaxation of residual stress can be promoted. Therefore, unintended deformation of the resin portion due to variations in residual stress can be suppressed, and damage to the current collector, which is a metal foil, can be suppressed. Therefore, the non-defective product rate of the power storage module can be improved.

In the method for manufacturing an electricity storage module, the main surface includes a first main surface and a second main surface located opposite to the first main surface in the thickness direction of the current collector, and the resin portion includes a first resin portion welded to the first main surface and a second resin portion welded to the second main surface, and the disposing step includes the first resin portion before welding. on the first principal surface; and a second arranging step of arranging the second resin portion before welding on the second principal surface. The preheating is performed by sandwiching and pressing the first resin portion and the arranged second resin portion from the first main surface side and the second main surface side, and in the welding step, the preheating is performed. The first resin portion and the preheated second resin portion are sandwiched and pressed from the first main surface side and the second main surface side to perform the welding together, and the first main surface The first resin portion may be welded to the main surface and the second resin portion may be welded to the second main surface.

According to this, the resin portions are welded to both the first main surface and the second main surface through the preheating step and the welding step. As a result, compared to the case where the resin portions are welded one by one to one of the main surfaces, the force exerted on the current collector due to the heat shrinkage of the resin portion tends to be applied to the current collector evenly from both sides of the main surface. Therefore, unintended deformation of the resin portion can be suppressed, and damage to the current collector, which is a metal foil, can be suppressed. Therefore, the non-defective product rate of the power storage module can be further improved.

In the method for manufacturing an electric storage module, in the arranging step, the resin portion before welding is arranged on the main surface so that a part of the resin portion protrudes from the periphery of the main surface, and in the laminating step, the Of the resin portions of the stacked electrode units, portions protruding from the periphery of the main surface of the current collector may be integrated.

According to this, in the electrode units that are adjacent to each other by stacking, the portions of the resin portions protruding from the peripheral edge of the main surface are integrated with each other. Here, the portion of the resin portion protruding from the periphery of the main surface is not welded to the main surface of the current collector. Therefore, the resin portions are integrated with each other at a portion different from the portion where the resin portion is welded to the main surface in the welding step. As a result, it is possible to reduce the influence of the integration on the portion of the resin portion that is welded to the main surface. Therefore, it is possible to suppress unintended deformation of the resin portion at the time of integration, and further suppress damage to the current collector, which is a metal foil. Therefore, the non-defective product rate of the power storage module can be further improved.

ADVANTAGE OF THE INVENTION According to this invention, the non-defective product rate of an electrical storage module can be improved.

FIG. 3 is a plan view of an electrode unit included in the power storage module; FIG. 4 is a side view of an electrode unit included in the power storage module; It is a figure for demonstrating the structure of an electrical storage module manufacturing apparatus. 4 is a sectional view taken along line 4-4 of FIG. 3; FIG. It is a figure for demonstrating the manufacturing method of an electrical storage module. (a) It is a figure for explaining the change of the resin temperature in each process, (b) It is a figure for explaining the change of the resin pressure in each process.

<Configuration>
An embodiment of a method for manufacturing an electric storage module will be described below. A power storage module includes a plurality of electrode units.

As shown in FIGS. 1 and 2, the electrode unit 10 includes an electrode plate 11, a first resin portion 20 as a resin portion, and a second resin portion 30 as a resin portion.
The electrode plate 11 is a bipolar electrode. The electrode plate 11 includes a current collector 12 , a first active material layer 16 and a second active material layer 17 .

The current collector 12 is made of metal foil. The current collector 12 is, for example, copper foil, aluminum foil, titanium foil, or nickel foil. From the viewpoint of ensuring mechanical strength, the current collector 12 may be a stainless steel foil (for example, SUS304, SUS316, SUS301, etc. defined in JIS G 4305:2015). The current collector 12 may be an alloy foil of any of the metals described above, or a combination of a plurality of metal foils described above. The surface of the current collector 12 may be subjected to known plating or surface treatment. The thickness of the current collector 12 is, for example, 1 μm or more and 100 μm or less, more specifically, 5 μm or more and 70 μm or less. The current collector 12 has a rectangular sheet shape, more specifically, a rectangular sheet shape. The electrode plate 11 is not limited to the form described above, and may be formed by simply stacking two metal foils.

Current collector 12 has a major surface 13 . The main surface 13 is a surface perpendicular to the thickness direction of the current collector 12 . Principal surface 13 includes a first principal surface 14 and a second principal surface 15 . The second main surface 15 is located opposite to the first main surface 14 in the thickness direction of the current collector 12 .

The first active material layer 16 as an active material layer contains a positive electrode active material. The positive electrode active material is capable of intercalating and deintercalating charge carriers such as lithium ions. Examples of positive electrode active materials include, for example, composite oxides, metallic lithium, sulfur, and the like. The first active material layer 16 may contain a conductive aid, a binder, and other components as necessary. The first active material layer 16 is integrally adhered to the first major surface 14 . The thickness of the first active material layer 16 is, for example, 2 to 150 μm. Examples of a method for adhering the first active material layer 16 to the first major surface 14 include known methods such as roll coating.

In addition, the 1st main surface 14 contains the 1st uncoated surface 14a. The first uncoated surface 14a is a region where the first active material layer 16 is not adhered. The first uncoated surface 14 a includes a first peripheral edge 14 b that is the peripheral edge of the first major surface 14 .

The second active material layer 17 as an active material layer contains a negative electrode active material. The negative electrode active material is capable of intercalating and deintercalating charge carriers such as lithium ions. Examples of negative electrode active materials include, for example, graphite, carbon, metal compounds, elements that can be alloyed with lithium or compounds thereof, boron-added carbon, and the like. The second active material layer 17 may contain a conductive aid, a binder, and other components as necessary. The thickness of the second active material layer 17 is, for example, 2 to 150 μm. The second active material layer 17 is integrally adhered to the second main surface 15 . The thickness of the second active material layer 17 is, for example, 2 to 150 μm. Examples of a method for adhering the second active material layer 17 to the second main surface 15 include a known method such as a roll coating method.

In addition, the 2nd main surface 15 contains the 2nd uncoated surface 15a. The second uncoated surface 15a is a region where the second active material layer 17 is not adhered. The second uncoated surface 15 a includes a second peripheral edge 15 b that is the peripheral edge of the second major surface 15 .

The first resin portion 20 is formed in a frame shape. Also, the first resin portion 20 is formed in a rectangular shape. The first resin portion 20 has four first side portions 21 . Each first side portion 21 is formed in a quadrangular prism shape. The ends of the first side portions 21 are connected to each other. Each first side 21 faces one of the other first sides 21 .

The first resin portion 20 is welded to the first main surface 14 . Specifically, the first resin portion 20 is welded to the first uncoated surface 14a. The first resin portion 20 is welded along the first peripheral edge 14b. It can also be said that the first resin portion 20 is welded to the first main surface 14 so as to surround the first active material layer 16 . Part of the first resin portion 20 protrudes from the first peripheral edge 14b over the entire circumference of the first peripheral edge 14b in a direction away from the region where the first active material layer 16 is adhered.

The second resin portion 30 is formed in a frame shape. Also, the second resin portion 30 is formed in a rectangular shape. The second resin portion 30 has four second side portions 31 . Each second side portion 31 is formed in a quadrangular prism shape. The ends of the second side portions 31 are connected to each other. Each second side portion 31 faces one of the other second side portions 31 .

The second resin portion 30 is welded to the second main surface 15 . Specifically, the second resin portion 30 is welded to the second uncoated surface 15a. The second resin portion 30 is welded along the second peripheral edge 15b. It can also be said that the second resin portion 30 is welded to the second main surface 15 so as to surround the second active material layer 17 . Part of the second resin portion 30 protrudes from the second peripheral edge 15b over the entire circumference of the second peripheral edge 15b in the direction away from the region where the second active material layer 17 is adhered.

The first resin portion 20 and the second resin portion 30 are made of insulating resin. Examples of materials for the first resin portion 20 and the second resin portion 30 include various resin materials such as polyethylene (PE), polystyrene (PS), polypropylene (PP), ABS resin, and AS resin, and these resin materials. can be used.

The electric storage module B is configured by stacking the electrode units 10 configured in this manner with the resin portions 20 and 30 interposed therebetween. Of the resin portions 20 and 30 of the stacked electrode units 10, the portions protruding from the peripheral edges 14b and 15b are integrated with each other by, for example, an adhesive member. As the adhesive member, for example, the resin materials exemplified for the resin portions 20 and 30 are used. The power storage module B of this embodiment is a bipolar lithium ion storage battery. The power storage module B is used, for example, as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles.

<Energy storage module manufacturing equipment>
Next, an example of a power storage module manufacturing apparatus for manufacturing the power storage module B will be described.

As shown in FIGS. 3 and 4, the power storage module manufacturing apparatus 40 manufactures the electrode unit 10 by welding the first resin portion 20 and the second resin portion 30 to the current collector 12, and This is an apparatus for manufacturing an electric storage module B by stacking a plurality of units 10 . The storage module manufacturing apparatus 40 includes two pressing units 41 , a heating section 42 , a pressure sensor 43 , a temperature sensor 44 and a control circuit 45 .

The two pressing units 41 press the resin portions 20 and 30 toward the current collector 12, respectively. Hereinafter, for convenience of explanation, the direction in which the pressing unit 41 presses the resin portions 20 and 30 toward the current collector 12 will be referred to as the pressing direction. The pressing direction coincides with the stacking direction. In addition, the pressing direction also coincides with the thickness direction of the current collector 12 .

In this embodiment, the two pressing units 41 press the first side portion 21 and the second side portion 31 of the resin portions 20 and 30 toward the current collector 12, respectively. The two pressing units 41 are arranged apart from each other in a direction perpendicular to the pressing direction. As a result, the first side portion 21 and the second side portion 31 pressed by one of the pressing units 41 and the first side portion 21 and the second side portion 31 pressed by the other pressing unit 41 are perpendicular to the stacking direction. facing away from each other. The two pressing units 41 each include a first pressing portion 41a and a second pressing portion 41b.

The first pressing portion 41 a presses the first side portion 21 toward the current collector 12 .
The second pressing portion 41 b presses the second side portion 31 toward the current collector 12 . The second pressing portion 41b is separated from the first pressing portion 41a in the pressing direction. The second pressing portion 41b overlaps the first pressing portion 41a in plan view from the pressing direction. As a result, the first pressing portion 41a and the second pressing portion 41b forming the same pressing unit 41 form a pair with each other. Hereinafter, the first pressing portion 41a and the second pressing portion 41b forming a pair may be collectively referred to as a pair of pressing portions 41a and 41b. A current collector 12 and resin portions 20 and 30 are arranged between the pair of pressing portions 41a and 41b. A heater wire (not shown) is arranged in each of the pressing portions 41a and 41b.

When the current collector 12 and the resin parts 20 and 30 are arranged between a pair of pressing parts 41a and 41b, at least part of the first pressing part 41a is connected to the current collector through the first resin part 20. 12 faces the first main surface 14 . At this time, at least part of the second pressing portion 41 b faces the second main surface 15 of the current collector 12 with the second resin portion 30 interposed therebetween. That is, the pair of pressing portions 41a and 41b are arranged facing each other so as to press the current collector 12, the first resin portion 20, and the second resin portion 30. As shown in FIG. The pair of pressing portions 41a and 41b are configured to be relatively movable in the pressing direction. The pair of pressing portions 41 a and 41 b come into contact with the resin portions 20 and 30 by relatively approaching each other through the current collector 12 and the resin portions 20 and 30 . After contacting the resin portions 20 and 30, the pair of pressing portions 41a and 41b move relatively closer to each other in the pressing direction, so that the first resin portion 20 moves toward the first peripheral edge 14b and the second resin portion 30 moves toward the second peripheral edge. 15b, respectively. As a result, the pair of pressing portions 41a and 41b sandwich and press the first resin portion 20 and the second resin portion 30 toward the current collector 12 from the first main surface 14 side and the second main surface 15 side. In addition, the pressing portions 41a and 41b may be provided with a welding suppressing portion TF. The welding suppressing portion TF can be provided on the contact surfaces between the pressing portions 41 a and 41 b and the resin portions 20 and 30 . Thereby, it is possible to prevent the resin portions 20 and 30 from being welded to the pressing portions 41a and 41b. The welding suppressing portion TF is a sheet-like member containing, for example, fluororesin. Note that the welding suppressing portion TF may be formed by subjecting the pressing portions 41a and 41b to surface treatment such as fluororesin coating.

The heating part 42 is configured to be able to heat the first resin part 20 and the second resin part 30 . The heating part 42 of the present embodiment is of a pulse heater type that heats the first resin part 20 and the second resin part 30 by Joule heat generated when an electric current is applied to the heater wires provided in the pressing parts 41a and 41b. is. The heating portion 42 is configured integrally with the pressing portions 41a and 41b. The specific mode and heating means of the heating unit 42 are not limited to this, and heating by an external heater, ultrasonic heating, laser heating, and the like are optional.

The pressure sensor 43 is a sensor that can detect the resin pressure P that the pressing unit 41 applies to the resin portions 20 and 30 . Any specific aspect of the pressure sensor 43 can be adopted, such as an oil pressure sensor, a gauge sensor, or the like.

The temperature sensor 44 is a sensor that can detect the resin temperature T, which is the temperature of the resin portions 20 and 30 . Any specific mode of the temperature sensor 44 can be adopted, such as a thermistor, a thermocouple, a resistance thermometer, or a radiation thermometer.

The control circuit 45 includes a processor and a storage section. As the processor, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or a DSP (Digital Signal Processor) is used. The storage unit includes RAM (Random Access Memory) and ROM (Read Only Memory). The memory stores program code or instructions configured to cause the processor to perform processes. Storage or computer-readable media includes any available media that can be accessed by a general purpose or special purpose computer. The control circuit 45 may be configured by a hardware circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The control circuit 45, which is a processing circuit, may include one or more processors operating according to a computer program, one or more hardware circuits such as ASICs and FPGAs, or a combination thereof.

The control circuit 45 is configured to be able to acquire the resin pressure P from the pressure sensor 43 . Also, the control circuit 45 is configured to be able to acquire the resin temperature T from the temperature sensor 44 . The control circuit 45 controls the pressing unit 41 and the heating section 42 so that the obtained resin pressure P and resin temperature T become the respective target values.

<Method for manufacturing power storage module>
Next, each step of the method for manufacturing the storage module B using the storage module manufacturing apparatus 40 will be described.

As shown in FIGS. 5 and 6, the method for manufacturing the power storage module B includes an arrangement step S1, a contact step S2, a first transition step S3, a preheating step S4, a second transition step S5, and a welding step S6. , a cooling step S7, a determination step S8, a changing step S9, and a stacking step S10. Each step S1 to S10 is performed, for example, on a work table (not shown). In FIGS. 6A and 6B, H1 indicates the resin temperature T and the resin pressure P in steps S1 to S7, respectively.

In the placement step S<b>1 , the resin parts 20 and 30 before welding are placed on the main surface 13 of the current collector 12 . Specifically, the first resin portion 20 is arranged on the first main surface 14 (more specifically, the first uncoated surface 14a). Also, the second resin portion 30 is arranged on the second main surface 15 (more specifically, the second uncoated surface 15a). Therefore, it can be said that the arranging step S<b>1 includes a first arranging step of arranging the first resin portion 20 on the first main surface 14 . Further, it can be said that the arranging step S1 includes a second arranging step of arranging the second resin portion 30 on the second main surface 15 .

In the arrangement step S1, the resin portions 20 and 30 are arranged on the main surfaces 13 and 14 so that parts of the resin portions 20 and 30 protrude from the peripheral edges 14b and 15b of the main surfaces 14 and 15, respectively. Specifically, the first resin portion 20 is arranged such that a portion of the first resin portion 20 protrudes from the first peripheral edge 14b. Further, the second resin portion 30 is arranged such that a portion of the second resin portion 30 protrudes from the second peripheral edge 15b. At this time, the thickness direction of the current collector 12 is parallel to the pressing direction. It is assumed that the electrode plate 11 is prepared in advance by a known method. Moreover, the specific arrangement method is arbitrary.

Next, the control circuit 45 proceeds to the contact step S2, and brings the two pressing units 41 into contact with the first resin portion 20 and the second resin portion 30, respectively. Specifically, the control circuit 45 brings the first pressing portions 41a into contact with the first resin portion 20 from the first main surface 14 side. Further, the control circuit 45 brings the second pressing portions 41b into contact with the second resin portion 30 from the second main surface 15 side. As a result, the two pressing units 41 sandwich the first resin portion 20 and the second resin portion 30 arranged in the arrangement step S1 on the first main surface 14 side and the second main surface 15 side. At this time, the pressing portions 41a and 41b are in direct contact with the resin portions 20 and 30, respectively. In other words, no member other than the resin portions 20 and 30 and the current collector 12 to which the resin portions 20 and 30 are to be welded is interposed between the pair of pressing portions 41a and 41b.

The control circuit 45 brings the pressing portions 41 a and 41 b closer to the side portions 21 and 31 of the resin portions 20 and 30 . When the resin pressure P becomes equal to or higher than the contact pressure Pc, the control circuit 45 determines that the pressing portions 41a and 41b are in contact with the side portions 21 and 31 of the resin portions 20 and 30, respectively. The contact pressure Pc can be arbitrarily set according to the materials of the current collector 12 and the resin portions 20 and 30, for example. If the resin pressure P does not reach or exceed the contact pressure Pc for a predetermined confirmation period, the control circuit 45 determines that contact failure between the pressing portions 41a and 41b and the resin portions 20 and 30 has occurred. If it is determined that the contact failure has occurred, the control circuit 45 may perform processing such as notifying the surroundings of the contact failure using a notification lamp or the like. Possible causes of such poor contact include, for example, deformation of the resin portions 20 and 30 and misalignment of the resin portions 20 and 30 with respect to the current collector 12 .

Next, proceeding to the first transition step S3, the control circuit 45 uses the pressing unit 41 to change the first side portion 21 of the first resin portion 20 so that the resin pressure P changes from the contact pressure Pc to the preheating pressure P1. And the second side portion 31 of the second resin portion 30 is pressed toward the main surfaces 14 and 15 . The preheating pressure P1 is arbitrary as long as the deformation in the thickness direction due to softening of the resin portions 20 and 30 can be regulated. The preheating pressure P1 may be obtained from a test or the like, or may be obtained from a simulation or the like.

When the control circuit 45 determines that the resin pressure P has been increased to the preheating pressure P1, the heating unit 42 is used to increase the resin temperature T to the first temperature T1. The side portion 21 and the second side portion 31 of the second resin portion 30 are heated. The first temperature T1 is equal to or higher than the softening point Tr of the resin portions 20 and 30 and lower than the melting point Tm of the resin portions 20 and 30 . Hereinafter, for convenience of explanation, the softening point Tr of the resin portions 20 and 30 is simply referred to as the softening point Tr, and the melting point Tm of the resin portions 20 and 30 is simply referred to as the melting point Tm. The softening point Tr is the lowest temperature at which the resin portions 20 and 30 soften. The softening point Tr in this embodiment is the glass transition point of the resin portions 20 and 30 . Depending on the properties of the materials used for the resin portions 20 and 30, the deflection temperature under load, the Vicat softening temperature, or the like may be employed as the softening point Tr. Further, when the resin portions 20 and 30 are formed of an amorphous resin, the softening point Tr may be a temperature lower than the glass transition point by a predetermined temperature. Although the predetermined temperature depends on the materials of the resin parts 20 and 30, it is, for example, 10°C to 40°C, more preferably 20°C to 30°C. Hereinafter, for convenience of explanation, a state in which the resin portions 20 and 30 are softened may be referred to as a softened state.

Next, the control circuit 45 proceeds to the preheating step S4, and the control circuit 45 heats the side portions 21, 21 of the resin portions 20, 30 using the heating portion 42 so that the resin temperature T is maintained at the softening point Tr or more and below the melting point Tm. 31 is heated. In this embodiment, during the preheating step S4, the resin temperature T is the first temperature T1 and is kept constant within the allowable error range. The allowable error can be set arbitrarily.

The preheating period tr, which is the period during which the preheating step S4 continues, is, for example, the temperature of the interface of the first resin portion 20 in contact with the first peripheral edge 14b and the temperature of the interface of the second resin portion 30 in contact with the second peripheral edge 15b. is longer than the period required for both to reach the softening point Tr. Note that the preheating period tr is not limited to this and can be set arbitrarily.

When the resin portions 20 and 30 are provided with an acid-modified group such as acid-modified polyethylene, the first temperature T1 and the preheating period tr are preferably the temperature and period necessary for activating the acid-modified group. Such a first temperature T1 depends on the material of the resin parts 20 and 30, but is in the range of 80°C to 120°C or 90°C to 110°C, for example. Note that the first temperature T1 and the preheating period tr may be determined by testing or the like according to the material and size of the resin portions 20 and 30 .

Next, proceeding to the second transition step S5, the control circuit 45 uses the pressing unit 41 to adjust the first side portion 21 of the first resin portion 20 so that the resin pressure P changes from the preheating pressure P1 to the welding pressure P2. And the second side portion 31 of the second resin portion 30 is pressed toward the main surfaces 14 and 15 . The welding pressure P2 is higher than the preheating pressure P1. The welding pressure P2 is arbitrary as long as the pressure allows the resin portions 20 and 30 to be welded. The welding pressure P2 may be obtained from a test or the like, or may be obtained from a simulation or the like.

When the control circuit 45 determines that the resin pressure P has increased to the welding pressure P2, the heating unit 42 is used to increase the resin temperature T from the first temperature T1 to the second temperature T2. The first side portion 21 of the portion 20 and the second side portion 31 of the second resin portion 30 are heated. The second temperature T2 is equal to or higher than the melting point Tm. The second temperature T2 may be, for example, the temperature at which the resin portions 20 and 30 deteriorate or lower. The temperature at which the resin portions 20 and 30 deteriorate is, for example, the temperature at which the resin portions 20 and 30 undergo thermal decomposition.

Next, proceeding to the welding step S6, the control circuit 45 heats the side portions 21, 31 of the resin portions 20, 30 using the heating portion 42 so as to keep the temperature above the melting point Tm. In this embodiment, during the welding step S6, the resin temperature T is the second temperature T2 and is kept constant within the allowable error range. The allowable error can be set arbitrarily.

The welding period tm, which is the period during which the welding step S6 continues, is, for example, the temperature of the interface of the first resin portion 20 in contact with the first peripheral edge 14b and the temperature of the interface of the second resin portion 30 in contact with the second peripheral edge 15b. is longer than the period required for both to reach the melting point Tm. Specifically, the preheating period tr is at least 2 seconds, preferably at least 4 seconds, more preferably at least 5 seconds. Note that the melting point Tm is not limited to this and can be arbitrarily set. The total of the preheating period tr and the welding period tm is preferably at least 5 seconds, more preferably at least 7 seconds, and even more preferably at least 10 seconds.

Next, proceeding to the cooling step S7, the control circuit 45 cools the resin portions 20 and 30 by controlling the heating portion 42 so that the resin temperature T is less than the softening point Tr. When the control circuit 45 determines that the resin temperature T is lower than the softening point Tr, the control circuit 45 reduces the resin pressure P to separate the pressing unit 41 from the side portions 21 and 31 of the resin portions 20 and 30 . In this embodiment, the control circuit 45 performs the pressure reduction when determining that the resin temperature T is lower than the softening point Tr by a predetermined buffer temperature. Although the buffer temperature can be set arbitrarily, it may be set based on the difference between the softening point Tr of the resin portions 20 and 30 and the supercooling temperature of the resin portions 20 and 30, for example. The supercooling temperature of the resin portions 20 and 30 is the temperature at which the resin portions 20 and 30 are kept in a softened state even when the resin temperature T becomes lower than the softening point Tr during the cooling process of the resin portions 20 and 30 . As a result, the side portions 21 and 31 of the melted resin portions 20 and 30 are welded to the main surfaces 14 and 15 of the current collector 12 .

Next, proceeding to determination step S8, the control circuit 45 determines whether or not all the first side portions 21 and the second side portions 31 are welded. The determination method is arbitrary, and may be determined from the number of times each step S2 to S7 is performed after the placement step S1, or by image identification using the images of the resin portions 20 and 30 captured by the imaging device. may

If the determination result in the determination step S8 is negative, the process proceeds to a change step S9 to change the side portions 21 and 31 to be welded, and returns to the contact step S2. The change method is arbitrary, and the pressing portions 41a and 41b may be moved onto the non-welded side portions 21 and 31, or the current collector 12 and the resin portions 20 and 30 that have undergone the cooling step S7 may be moved in the pressing direction. may be rotated 90° in a plane perpendicular to . The rotation method is also arbitrary, and the current collector 12 and the resin portions 20 and 30 that have undergone the cooling step S7 may be rotated together with the workbench, or may be rotated by picking with a robot arm or the like.

On the other hand, when the determination result in the determination step S8 is affirmative, the control circuit 45 determines that the manufacturing of the electrode unit 10 is completed, and proceeds to the stacking step S10.
In the stacking step S10, when the number of electrode units 10 manufactured through the steps S1 to S9 reaches a predetermined number, the electricity storage module manufacturing apparatus 40 stacks the electrode units 10 of that number. In this embodiment, the first active material layer 16 of a certain electrode unit 10 is laminated so as to face the second active material layer 17 of another electrode unit 10 via a separator (not shown). As a result, in the stacking step S10, the storage module manufacturing apparatus 40 manufactures the storage module B including the plurality of electrode units 10 that have undergone the welding step S6. In addition, arbitrary well-known methods are used for the lamination method.

In the stacking step S10, the power storage module manufacturing apparatus 40 of the present embodiment further integrates protruding portions of the resin portions 20 and 30 of the stacked electrode units 10 . Although any method can be used to integrate the resin parts 20 and 30, the power storage module manufacturing apparatus 40 heats and melts protruding portions of the resin parts 20 and 30 in a state in which a plurality of electrode units 10 are stacked, for example. , the resin portions 20 and 30 adjacent to each other in the stacking direction may be integrated.

<Action>
Next, the operation of this embodiment will be described. First, a comparative example will be described with reference to FIG. In FIG. 6, H2 shows an outline of the resin temperature T and the resin pressure P in each step in the manufacturing method of the comparative example.

In the method of manufacturing the power storage module B as a comparative example, the preheating step S4 is not performed, and the contact step S2 goes through a predetermined step of increasing the temperature and increasing the temperature, and then proceeds to the welding step S6. In this case, the resin parts 20 and 30 are welded while the residual stress variations in the resin parts 20 and 30 remain unrelieved. Therefore, the deformation of the resin parts 20 and 30 at the time of melting also varies due to variations in residual stress. Therefore, unintended deformation of the resin portions 20 and 30 may damage the current collector 12 .

On the other hand, in this embodiment, the preheating step S4 is performed before the welding step S6. In the preheating step S4, the resin temperature T, which is the temperature of the resin portions 20 and 30, is kept below the melting point Tm. Therefore, in the preheating step S4, welding of the resin portions 20 and 30 is suppressed. On the other hand, in the preheating step S4, the first temperature T1 is kept at or above the softening point Tr. When the resin temperature T becomes equal to or higher than the softening point Tr, the resin portions 20 and 30 undergo a phase transition from a solid state to a glass state. The mobility of the molecules (especially polymer chains) that constitute the resin portions 20 and 30 in the glass state is higher than that in the solid state. Therefore, in the glass state, the time required to relax the residual stress of the resin portions 20 and 30 is shorter than in the solid state. Therefore, in the preheating step S4, the softening of the resin portions 20 and 30 and the relaxation of the residual stress of the resin portions 20 and 30 are promoted. As a result, in the subsequent welding step S6, the resin portions 20 and 30 in which variations in residual stress are suppressed are welded to the main surface 13 of the current collector 12. Damage to the current collector 12 is suppressed.

Furthermore, in the preheating step S4 of the present embodiment, the resin portions 20 and 30 are pressed so that the resin pressure P becomes the preheating pressure P1 during heating. At this time, deformation in the thickness direction (in other words, pressing direction) of the resin portions 20 and 30 due to softening is restricted. Such deformation includes, for example, warping and bending of the resin portions 20 and 30 .

Since the preheating pressure P1 is lower than the welding pressure P2, excessive pressure is suppressed from being applied to the resin portions 20 and 30 during preheating in the preheating step S4. This promotes relaxation of residual stress in the resin portions 20 and 30 . Moreover, if the hardness of the resin portions 20 and 30 temporarily varies during the softening process, the resin pressure P may be concentrated in a region where the residual stress is slow to relax. Therefore, by suppressing excessive pressure from being applied to the resin portions 20 and 30, concentration of the pressure to be applied to the main surfaces 14 and 15 is suppressed. As a result, the load on the current collector 12 due to the pressing of the resin portions 20 and 30 in the preheating step S4 can be reduced.

<effect>
(1) The method for manufacturing the power storage module B of the present embodiment includes an arrangement step S1, a preheating step S4, a welding step S6, and a stacking step S10. In the preheating step S4, the pre-welding resin portions 20 and 30 arranged in the arrangement step S1 are pressed against the main surface 13 of the current collector 12 with a preheating pressure P1, and the resin temperature T, which is the temperature of the resin portions 20 and 30, is increased. is maintained above the softening point Tr and below the melting point Tm, the resin portions 20 and 30 are preheated. The preheating pressure P1 is lower than the welding pressure P2, which is the resin pressure P in the welding step S6.

According to this, the preheating step S4 is performed before the resin portions 20 and 30 are welded to the main surface 13 of the current collector 12 in the welding step S6. In the preheating step S4, the resin temperature T is kept at the softening point Tr or more and below the melting point Tm, so that the welding of the resin parts 20 and 30 to the current collector 12 is suppressed and the softening of the resin parts 20 and 30 is promoted. be done. The softening of the resin portions 20 and 30 relaxes the residual stress of the resin portions 20 and 30 . As a result, variations in the residual stress of the resin portions 20 and 30 are reduced before the welding step S6.

On the other hand, along with the relaxation of the residual stress, unintended deformation of the resin portions 20 and 30 such as bending and waviness may occur. Therefore, in the preheating step S4, the resin portions 20 and 30 are pressed against the main surface 13 of the current collector 12 with a preheating pressure P1. As a result, when the residual stress is relaxed in the preheating step S4, the resin portions 20 and 30 are deformed in a direction perpendicular to the main surface 13 of the current collector 12 (in other words, in the thickness direction of the current collector 12). can be regulated. Therefore, unintended deformation of the resin portions 20 and 30 due to variations in residual stress can be suppressed, and damage to the current collector 12, which is a metal foil, can be suppressed.

(2) The arranging step S1 includes a first arranging step of arranging the first resin portion 20 on the first main surface 14 and a second arranging step of arranging the second resin portion 30 on the second main surface 15. . In the preheating step S4, the preheating is performed by sandwiching and pressing the first resin portion 20 and the second resin portion 30 from the first main surface 14 side and the second main surface 15 side. In the welding step S6, the welding is performed by sandwiching and pressing the first resin portion 20 and the second resin portion 30 from the first main surface 14 side and the second main surface 15 side.

According to this, the resin portions 20 and 30 are welded to both surfaces of the first main surface 14 and the second main surface 15 through the preheating step S4 and the welding step S6. As a result, compared to the case where the resin portions 20 and 30 are welded to one of the main surfaces 14 and 15 one by one, the force exerted on the current collector 12 due to thermal contraction of the resin portions 20 and 30 is evenly applied from both surfaces of the main surface 13. It tends to act on the current collector 12 at the same time. Therefore, unintended deformation of the resin portions 20 and 30 can be suppressed, and damage to the current collector 12, which is a metal foil, can be suppressed.

(3) In the arranging step S1, the resin parts 20 and 30 before welding are arranged on the main surfaces 14 and 15 so that parts of the resin parts 20 and 30 protrude from the peripheral edges 14b and 15b of the main surfaces 14 and 15. do. In the stacking step S10, portions of the resin portions 20 and 30 of the stacked electrode units 10 that protrude from the peripheral edges 14b and 15b of the main surfaces 14 and 15 of the current collector 12 are integrated.

According to this, in the stacked electrode units 10, the portions of the resin portions 20 and 30 protruding from the peripheral edges 14b and 15b of the main surfaces 14 and 15 are integrated. Here, portions of the resin portions 20 and 30 protruding from the main surfaces 14 and 15 are not welded to the main surfaces 14 and 15 of the current collector 12 . Therefore, portions of the resin portions 20 and 30 that are different from the portions welded to the main surfaces 14 and 15 in the welding step S6 are integrated in the lamination step S10. As a result, when the resin portions 20 and 30 are integrated, the influence on the portions of the resin portions 20 and 30 that are welded to the main surfaces 14 and 15 can be reduced. Therefore, unintended deformation of the resin portions 20 and 30 during integration can be suppressed, and damage to the current collector 12, which is a metal foil, can be further suppressed.

(4) In the first transition step S3 and the second transition step S5, the control circuit 45 raises the resin temperature T after raising the resin pressure P.
According to this, deformation such as warping of the resin portions 20 and 30 due to the rise in the resin temperature T is restricted by pressing. Therefore, it is possible to suppress deterioration in the contactability of the resin portions 20 and 30 with the main surface 13 due to deformation of the resin portions 20 and 30 due to temperature rise.

<Modification>
Embodiments can be implemented with the following modifications. The embodiments and the following modified examples can be implemented in combination with each other within a technically consistent range.

○ The order of increasing the pressure and increasing the temperature in each step S1 to S8 can be arbitrarily changed. Moreover, the pressure increase and the temperature increase may not be performed separately, and may be performed in parallel.
○ If the placement step S1, the preheating step S4, and the welding step S6 are realized, each step can be omitted as appropriate. For example, the contacting step S2 may be omitted. In this case, for example, contact determination between the pressing portions 41a and 41b and the resin portions 20 and 30 may be performed from transition of the resin pressure P detected by the pressure sensor 43 in the first transition step S3.

Also, the side portions 21 and 31 may be individually welded by combining a plurality of power storage module manufacturing apparatuses 40 . In this case, the determination step S8 and the change step S9 may be omitted.

○ The resin temperature T during the preheating step S4 is not limited to the first temperature T1, which is a constant temperature, and any temperature history can be adopted as long as it is equal to or higher than the softening point Tr and lower than the melting point Tm. In other words, during the preheating step S4, heating and cooling of the resin portions 20 and 30 may be arbitrarily performed as long as the resin temperature T is equal to or higher than the softening point Tr and lower than the melting point Tm. For example, during the preheating step S4, the resin temperature T may be raised from the softening point Tr to the melting point Tm at a constant heating rate. In this case, the temperature increase rate in the preheating step S4 is slower than the temperature increase rate in the first transition step S3. Similarly, in the welding step S6, any temperature history can be adopted as long as the resin temperature T during the welding step S6 is equal to or higher than the melting point Tm.

(circle) the 1st resin part 20 protrudes from the 1st peripheral edge 14b over the perimeter of the 1st peripheral edge 14b, and does not need to be welded. For example, the first resin portion 20 may be welded such that only a portion of the entire circumference of the first peripheral edge 14b protrudes from the first peripheral edge 14b. Similarly to the first resin portion 20, the second resin portion 30 does not need to be welded so as to protrude from the second peripheral edge 15b over the entire circumference of the second peripheral edge 15b.

(circle) the 1st resin part 20 protrudes from the 1st peripheral edge 14b, and does not need to be welded. Along with this, the first resin portion 20 does not need to be arranged to protrude from the first peripheral edge 14b. The first resin portion 20 may be welded to any location on the first main surface 14 . As with the first resin portion 20 , the second resin portion 30 may be welded to any location on the second main surface 15 .

○ Both the first resin portion 20 and the second resin portion 30 may not be welded to the current collector 12, and only one of the first resin portion 20 and the second resin portion 30 may be welded. may have been

○ The speed at which the resin temperature T is changed and the speed at which the resin pressure P is changed in each step are arbitrary.
(circle) the structure of the electrical storage module manufacturing apparatus 40 is an example to the last, and is not restricted to this. For example, the pressing unit 41 and the heating section 42 may be realized by heater rollers.

O The pressing unit 41 may not be configured to be able to press only the first side portion 21 and the second side portion 31 which are a part of the resin portions 20 and 30 . For example, the pressing unit 41 may be configured to be able to press the entire resin portions 20 and 30 .

Further, the heating portion 42 may not be provided on the pressing portions 41a and 41b. For example, the heating section 42 may be a heater unit provided separately from the pressing sections 41a and 41b. The specific mode of the heater unit is arbitrary, and it may be an electric furnace or an induction heating device.

DESCRIPTION OF SYMBOLS 10... Electrode unit, 12... Current collector, 13... Main surface, 14... First main surface, 14b... First peripheral edge, 15... Second main surface, 15b... Second peripheral edge, 16... First active material layer, 17... Second active material layer 20... First resin part 30... Second resin part B... Power storage module S1... Placement step S4... Preheating step S6... Welding step S10... Lamination step P... Resin Pressure, P1... Preheating pressure, P2... Welding pressure, T... Resin temperature, Tm... Melting point, Tr... Softening point.

Claims (3)

An electrode unit comprising: a current collector that is a metal foil; an active material layer provided on a main surface of the current collector; and a resin portion that is welded to the main surface so as to surround the active material layer. A method for manufacturing an electricity storage module including a plurality of
an arrangement step of arranging the resin portion before welding on the main surface;
Preheating to preheat the resin portion by pressing the arranged resin portion against the current collector with a preheating pressure and maintaining the temperature of the resin portion at a softening point or higher and a melting point of the resin portion or lower. process and
By pressing the preheated resin portion against the current collector with a welding pressure and maintaining the temperature of the resin portion at or above the melting point, the resin portion is welded to the main surface, thereby forming the electrode unit. a welding process to manufacture the
a stacking step of manufacturing the electricity storage module by stacking the electrode units that have undergone the welding step,
The method of manufacturing an electricity storage module, wherein the preheating pressure is lower than the welding pressure. the main surface includes a first main surface and a second main surface located opposite to the first main surface in the thickness direction of the current collector;
The resin portion includes a first resin portion welded to the first main surface and a second resin portion welded to the second main surface,
The arranging step includes a first arranging step of arranging the first resin portion before welding on the first main surface and a second arranging step of arranging the second resin portion before welding on the second main surface. , including
In the preheating step, the arranged first resin portion and the arranged second resin portion are sandwiched and pressed from the first main surface side and the second main surface side to perform the preheating,
In the welding step, the preheated first resin portion and the preheated second resin portion are sandwiched from the first main surface side and the second main surface side and pressed together. 2. The method of manufacturing an electric storage module according to claim 1, wherein the welding is performed, and the first resin portion is welded to the first main surface and the second resin portion is welded to the second main surface. In the arranging step, the resin portion before welding is arranged on the main surface so that a part of the resin portion protrudes from the peripheral edge of the main surface;
3. The power storage module according to claim 1, wherein, in said stacking step, of said resin portions of said stacked electrode units, portions protruding from peripheral edges of said main surface of said current collector are integrated. Production method.

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