Manufacturing method for energy storage modules

Abstract

To provide a method of manufacturing a power storage module for obtaining the power storage module with excellent sealing performance.SOLUTION: A method of manufacturing a power storage module includes: a preparation step of preparing a laminated body formed by laminating a plurality of electrode sheets in a thickness direction, the electrode sheet having an electrode equipped with a collector and an active material layer and plastic frame bodies arranged along an outer edge of the collector; a heating step of heating the frame body in the laminated body and welding adjacent frame bodies in the thickness direction to form a welded portion; an inspection step of performing fluoroscopic examination on corner parts of the laminated body to inspect variability of weld depth in the welded portion; and a determination step of determining a non-defective product or a defective product on the basis of the variability of the weld depth.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a power storage module.

Background Art

[0002] In a method for manufacturing a power storage module such as a secondary battery, it is known to provide a seal member on the outer edge of a plurality of stacked electrodes and seal the plurality of stacked electrodes. For example, Patent Document 1 discloses a power storage module including an electrode laminate and a seal member surrounding the electrode laminate, wherein the seal member has a primary seal provided at the peripheral edge of the current collector and a secondary seal covering the primary seal. Further, Patent Document 1 discloses that the primary seals adjacent to each other along the stacking direction are welded together.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Seal members such as the primary seal and the secondary seal need to have good sealing performance. In Patent Document 1, the primary seals (resin frames) stacked along the first direction (thickness direction) are welded together. The welding depth at the welded portion where the resin frames are welded together usually has variations in the thickness direction. Therefore, due to portions where the welding depth is insufficient, the sealing performance of the power storage module may be reduced.

[0005] The present disclosure has been made in view of the above circumstances, and the main object thereof is to provide a method for manufacturing a power storage module capable of obtaining a power storage module with good sealing performance.

Means for Solving the Problems

[0006] [1] A preparation step of preparing a laminate comprising an electrode sheet having an electrode having a current collector and an active material layer, and a resin frame arranged along the outer edge of the current collector, wherein a plurality of the electrode sheets are stacked in the thickness direction, A heating step involves heating the frame in the laminate to weld adjacent frame members in the thickness direction and form a welded portion. An inspection process is performed to inspect the corners of the laminated material for transparency and to check for variations in the welding depth at the welded area. A determination process to determine whether a product is good or defective based on the above variation in welding depth, A method for manufacturing an energy storage module having [the specified feature].

[0007] [2] A method for manufacturing an energy storage module according to [1], wherein in the inspection step described above, the corners of the laminate are inspected using an X-ray inspection device.

[0008] [3] The method for manufacturing an energy storage module according to [2], wherein, viewed from the thickness direction, the angle between the X-ray irradiation direction and the extension direction of the side surface of the frame is 30° or more and 60° or less.

[0009] [4] A method for manufacturing an energy storage module according to any one of [1] to [3], wherein, in the above determination step, if the minimum value of the welding depth in the normal direction of the side surface of the frame is 1 mm or more, it is determined to be a good product.

[0010] [5] The above electrode sheet is a method for manufacturing an energy storage module according to any one of [1] to [4], wherein the electrode sheet has a bipolar electrode as the electrode. [Effects of the Invention]

[0011] The method for manufacturing an energy storage module described herein has the effect of being able to produce an energy storage module with good sealing properties.

Brief Description of the Drawings

[0012] [Figure 1] They are a schematic plan view and a schematic cross-sectional view illustrating the laminate in the present disclosure. [Figure 2] It is a schematic cross-sectional view illustrating the heating process in the present disclosure. [Figure 3] It is a schematic cross-sectional view illustrating the frame (after the heating process) in the present disclosure. [Figure 4] It is a schematic plan view illustrating the inspection process in the present disclosure. [Figure 5] It is a schematic plan view illustrating the laminate in the present disclosure. [Figure 6] It is a schematic cross-sectional view illustrating the preparation process in the present disclosure.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, the method for manufacturing a power storage module in the present disclosure will be described in detail with reference to the drawings. Each of the following figures is schematically shown, and the size and shape of each part are appropriately exaggerated for easy understanding. Also, in this specification, when expressing the manner of arranging one member relative to another member, when simply described as "above" or "below", unless otherwise specified, it includes both the case where another member is arranged directly above or directly below so as to contact a certain member, and the case where another member is arranged above or below a certain member through another member.

[0014] The method for manufacturing a power storage module in the present disclosure includes a preparation step of preparing a laminate having an electrode sheet having a current collector and an active material layer, and a resin-made frame arranged along the outer edge of the current collector, and a plurality of the electrode sheets are laminated in the thickness direction; a heating step of heating the frame in the laminate, welding the adjacent frames in the thickness direction to form a welded portion; an inspection step of performing a fluoroscopy inspection on the corners of the laminate and inspecting the variation in the welding depth at the welded portion; and a determination step of determining a good product or a defective product based on the variation in the welding depth.

[0015] The preparation process in the present disclosure is a process of preparing a specific laminate. FIG. 1(a) is a schematic plan view illustrating the laminate in the present disclosure, and FIG. 1(b) is a cross-sectional view taken along the line A-A of FIG. 1(a). The laminate 10 shown in FIGS. 1(a) and 1(b) has a structure in which a plurality of electrode sheets ES are laminated in the thickness direction D1. The electrode sheet ES includes an electrode E having a current collector 1 and an active material layer (at least one of a positive electrode active material layer 2 and a negative electrode active material layer 3) disposed on the current collector 1. The laminate 10 shown in FIG. 1(b) has, as the electrode sheet ES, (i) an electrode sheet having a bipolar electrode BP, (ii) an electrode sheet having a positive electrode side end electrode CA, and (iii) an electrode sheet having a negative electrode side end electrode AN. Further, as shown in FIGS. 1(a) and 1(b), the electrode sheet ES has a resin-made frame body 5 disposed along the outer edge of the current collector 1.

[0016] The heating process in the present disclosure will be described with reference to FIG. 2. In FIG. 2, while applying a restraining pressure to the laminate 10 in the thickness direction D1 by a pair of restraining members 20 (20a, 20b), the side surface (end face) of the frame body 5 in the laminate 10 is heated using a radiant heater 30. As a result, as shown in FIG. 3, the adjacent frame bodies 5 in the thickness direction D1 are welded to form a welded portion 51. The frame body 5 after the heating process has a welded portion 51 and an unwelded portion 52 located on the electrode E side with respect to the welded portion 51. Further, as shown in FIG. 3, the welding depth in the welded portion 51 has variations in the thickness direction D1. Also, the inspection process in the present disclosure will be described with reference to FIG. 4(a). FIG. 4(a) is an enlarged view of the region X in FIG. 1(a). As shown in FIG. 4(a), a fluoroscopic inspection is performed on the corner portion of the laminate 10 using an X-ray inspection device 40. Thereby, as shown in FIG. 3, the variations in the welding depth in the welded portion 51 are inspected. Thereafter, based on the variations in the welding depth, a good product or a defective product is determined.

[0017] According to this disclosure, by performing a visual inspection on the corners of the laminate and checking for variations in welding depth at the welded portion, it is possible to easily determine whether or not the welding depth has reached a predetermined value. Furthermore, by using a laminate that has been judged as good quality, a storage module with good sealing performance can be obtained. As described above, sealing members such as primary seals and secondary seals need to have good sealing performance. In Patent Document 1, primary seals (resin frames) laminated along the first direction (thickness direction) are welded together. The welding depth at the welded portion where resin frames are welded together usually varies in the thickness direction. Therefore, the sealing performance of the storage module may be low due to areas with insufficient welding depth.

[0018] The welding depth in a welded area cannot be observed visually. One method for observing variations in welding depth in a welded area is non-destructive testing using an X-ray inspection device. However, even with an X-ray inspection device, depending on the inspection method, it may be difficult to accurately observe variations in welding depth in a welded area. For example, as shown in Figure 1(a), a beam is drawn in direction D, passing through the interior of the laminate 10. x When X-rays are irradiated along the thickness direction, halation occurs due to the current collector (typically metal foil), making it difficult to accurately observe variations in welding depth at the welded area. Also, although not specifically shown in the figures, even when X-rays are irradiated along the thickness direction, it is difficult to observe variations in welding depth at the welded area from the fluoroscopic image in the thickness direction. In contrast, in this disclosure, as shown in Figure 4(a), a fluoroscopic inspection is performed on the corners of the laminate 10 using an X-ray inspection device 40. This suppresses the occurrence of halation due to the current collector (typically metal foil), and allows for accurate observation of variations in welding depth at the welded area. Furthermore, by determining whether the welding depth has reached a predetermined value and using the laminate that has been judged as a good product, a storage module with good sealing performance can be obtained.

[0019] 1. Preparation process The preparation step in this disclosure is a step of preparing a laminate comprising an electrode sheet having an electrode having a current collector and an active material layer, and a resin frame arranged along the outer edge of the current collector, wherein a plurality of the electrode sheets are stacked in the thickness direction.

[0020] (1) Electrode sheet The electrode sheet comprises an electrode having a current collector and an active material layer, and a resin frame arranged along the outer edge of the current collector. The electrode comprises at least a current collector and an active material layer formed on one surface of the current collector. The active material layer may be a positive electrode active material layer or a negative electrode active material layer. The electrode may also have active material layers on both sides of the current collector.

[0021] As shown in Figure 1(b), the electrode sheet ES may have a bipolar electrode as the electrode E, comprising a current collector 1, a positive electrode active material layer disposed on one side of the current collector 1, and a negative electrode active material layer disposed on the other side of the current collector 1. Although not specifically shown, the electrode sheet may also have electrodes with positive electrode active material layers disposed on both sides of the current collector, or electrodes with negative electrode active material layers disposed on both sides of the current collector.

[0022] As shown in Figure 1(b), the electrode sheet ES may have a positive electrode end electrode CA as electrode E, which comprises a current collector 1 and a positive electrode active material layer 2 disposed on one side of the current collector 1. Alternatively, the electrode sheet ES may have a negative electrode end electrode AN as electrode E, which comprises a current collector 1 and a negative electrode active material layer 3 disposed on one side of the current collector 1.

[0023] As shown in Figures 1(a) and (b), the electrode sheet ES has a resin frame 5 arranged along the outer edge of the current collector 1. The resin used for the frame 5 is, for example, a thermoplastic resin. Examples of thermoplastic resins include polyolefins such as polyethylene and polypropylene. When the electrode sheet ES is viewed from the thickness direction, the frame 5 is usually arranged along the entire circumference of the outer edge of the current collector 1. The frame 5 is used to form a welded portion (seal portion), which will be described later, and the welded portion prevents leakage of the electrolyte. For example, if the outer edge shape of the electrode E (current collector 1) is rectangular, the frame 5 is arranged along the entire circumference of the outer edge of that rectangle. Furthermore, as shown in Figure 6, which will be described later, it is preferable that the frame 5 covers a part of one main surface p of the current collector 1, a part of the other main surface q of the current collector 1, and the entire side surface r that constitutes the outer edge of the current collector 1.

[0024] (2) Laminate As shown in Figures 1(a) and (b), the laminate 10 has a plurality of electrode sheets ES stacked in the thickness direction D1. Also, as shown in Figure 1(b), the laminate 10 may have a plurality of power generation units U (U1, U2, U3) stacked in the thickness direction D1. A power generation unit is usually a unit having a positive electrode active material layer, a separator, and a negative electrode active material layer. As will be described later, the power generation unit functions as a battery when an electrolyte is supplied to it. As shown in Figure 1(b), the plurality of power generation units U (U1, U2, U3) may be connected in series with each other. Also, although not specifically shown, the plurality of power generation units may be connected in parallel with each other.

[0025] In Figure 1(b), the power generation unit U1 has a positive electrode active material layer 2 in the bipolar electrode BP1, a negative electrode active material layer 3 in the negative electrode end electrode AN, and a separator 4 placed between them. The power generation unit U2 has a positive electrode active material layer 2 in the bipolar electrode BP2, a negative electrode active material layer 3 in the bipolar electrode BP1, and a separator 4 placed between them. Thus, a single power generation unit may be composed of two adjacent bipolar electrodes. The power generation unit U3 has a positive electrode active material layer 2 in the positive electrode end electrode CA, a negative electrode active material layer 3 in the bipolar electrode BP2, and a separator 4 placed between them.

[0026] The shape of the laminate when viewed from the thickness direction (plan view shape) is not particularly limited, but examples include quadrilaterals such as squares and rectangles. For example, the plan view shape of the laminate 10 shown in Figure 1 is a quadrilateral. The length of each side constituting the plan view shape of the laminate is not particularly limited, but each may be, for example, 30 cm or more, 50 cm or more, or 100 cm or more. On the other hand, each of the above side lengths may be, for example, 200 cm or less. As the size of the laminate increases, it becomes more difficult to control the airtightness. In this disclosure, even when the size of the laminate increases, a storage module with good airtightness can be obtained by performing the inspection and judgment processes described later.

[0027] As shown in Figure 5, the laminate 10 may have an insert 6. One end of the insert 6 is located inside the laminate 10 (in the space of the power generation unit), and the other end of the insert 6 is located outside the laminate 10. The insert 6 is also arranged to extend in a direction perpendicular to the thickness direction. After the heating process described later, the insert 6 is removed to form through holes for supplying electrolyte to each power generation unit. In addition, although not specifically shown, the laminate may have voltage detection terminals that extend in a direction perpendicular to the thickness direction for detecting the voltage of each power generation unit.

[0028] The method for fabricating the laminate is not particularly limited. As shown in Figure 6, the negative electrode active material layer 3 of the bipolar electrode BP1 and the positive electrode active material layer 2 of the bipolar electrode BP2 are placed opposite each other via a separator 4. In this case, another frame 5 (spacer 51) is placed between the frame 5 of the bipolar electrode BP1 and the frame 5 of the bipolar electrode BP2. Similarly, the positive electrode active material layer 2 of the bipolar electrode BP1 and the negative electrode active material layer 3 of the negative electrode end electrode AN are placed opposite each other via a separator 4. In this case, another frame 5 (spacer 51) is placed between the frame 5 of the bipolar electrode BP1 and the frame 5 of the negative electrode end electrode AN. Similarly, the negative electrode active material layer 3 of the bipolar electrode BP2 and the positive electrode active material layer 2 of the positive electrode end electrode CA are placed opposite each other via a separator 4. In this process, another frame 5 (spacer 51) is placed between the frame 5 of the bipolar electrode BP2 and the frame 5 of the positive electrode end electrode CA. In this way, the laminate 10 is obtained.

[0029] 2.Heating process The heating step in this disclosure is a step of heating the frame in the laminate, welding adjacent frame in the thickness direction, and forming a welded portion.

[0030] As shown in Figure 2, it is preferable to place a pair of restraining members 20 (20a, 20b) at a position that overlaps with the frame 5 in the laminate 10 when viewed from the thickness direction D1, and to heat the frame 5 in the laminate 10 while applying restraining pressure to the laminate 10 with the pair of restraining members 20 (20a, 20b). This is because adjacent frame members can be welded together with good sealing performance. The restraining pressure applied to the laminate by the restraining members is not particularly limited, but for example it can be 1 kPa or more and 30 MPa or less, or 0.1 MPa or more and 10 MPa or less. The restraining pressure can also be adjusted, for example, by clamps connected to the pair of restraining members.

[0031] In the heating process, the frame members in the laminate are heated to weld adjacent frame members in the thickness direction. In this disclosure, the side surfaces (surfaces extending in the thickness direction) of the frame members are usually heated to weld adjacent frame members in the thickness direction and form a welded portion (seal portion). The heating temperature is appropriately selected depending on the material of the frame members, but for example, it may be between 120°C and 300°C, or between 150°C and 250°C. Heating is performed using a radiant heater, such as an infrared lamp heater. For example, as shown in Figure 2, the side surface SS of the frame member 5 is heated using a radiant heater 30. The output of the infrared lamp is, for example, 100W or more per lamp, but may be 150W or more, or 300W or more.

[0032] The heating process is typically performed around the entire outer edge of the laminate. For example, if the outer edge shape of the laminate is rectangular when viewed from the thickness direction, the heating process is usually performed on all four sides.

[0033] 3. Inspection Process The inspection process in this disclosure is a process of performing a transparent inspection on the corners of the laminate and inspecting for variations in the welding depth at the welded portion. The corners of the laminate refer to the region that includes the vertices (corners) connecting the two sides that constitute the outer edge of the laminate 10, as shown in Figure 4(a), when viewing the laminate 10 from the thickness direction.

[0034] Fluoroscopy is preferably performed based on radiographic testing (RT). Examples of inspection equipment used for fluoroscopy include X-ray inspection equipment. X-ray inspection equipment includes a light emitter and a light receiver. Examples of light emitters include a microfocus X-ray source (Hamamatsu Photonics L9631). Examples of light receivers include an X-ray sensor (Hamamatsu Photonics C16401SK-51).

[0035] As shown in Figure 4(a), the X-ray emitter 41 and the photodetector 42 are arranged so that the X-rays pass through the corners of the laminate 10. Preferably, the emitter 41 and the photodetector 42 are arranged so that the X-rays emitted from the emitter 41 do not pass through the current collector in the laminate 10. On the other hand, if it is possible to inspect for variations in welding depth at the welded portion, some of the X-rays emitted from the emitter 41 may pass through the current collector in the laminate 10.

[0036] As shown in Figure 4(b), the X-ray irradiation direction D is as viewed from the thickness direction. A And the extension direction D of the side surface SS of frame 5 B Let θ be the angle between the X-ray beam and the side surface SS of the frame 5. The angle θ corresponds to the angle of incidence of the X-ray beam to the side surface SS of the frame 5. The angle θ is, for example, 30° or more and 60° or less, and may also be 40° or more and 50° or less. By having the angle θ within the above range, variations in the welding depth at the welded area can be accurately observed.

[0037] As shown in Figure 3, the frame 5 after the heating process has a welded portion 51 and an unwelded portion 52 located on the electrode E side of the welded portion 51. Preferably, the welded portion 51 extends from the side surface SS of the frame 5 toward the interior of the frame 5. The welded portion 51 and the unwelded portion 52 are determined by observing a translucent image.

[0038] 4. Judgment process The determination step in this disclosure is a step of determining whether a product is good or defective based on the variation in welding depth.

[0039] As shown in Figure 3, the welding depth in the welded portion 51 varies in the thickness direction D1. In Figure 3, the welding depth is greatest at height h1 and smallest at height h2. In this disclosure, it is preferable to determine that a product is good if the minimum welding depth is greater than or equal to a threshold, and that a product is defective if the minimum welding depth is less than the threshold. Furthermore, the minimum welding depth in the direction D2 normal to the side surface SS of the frame 5 is W min Let's assume that. W min It is preferable to determine that a product is good if the diameter is 1 mm or more.

[0040] As shown in Figure 4(b), let a be the welding depth on the fluoroscopic image. The welding depth a is determined by the X-ray irradiation direction D A Direction D perpendicular to the direction C This corresponds to the welding depth in the specified direction. On the other hand, let b be the welding depth in the direction D2 normal to the side surface SS of the frame 5. Furthermore, as described above, if the angle of incidence of X-rays on the side surface SS of the frame 5 is θ, then the welding depths a and b have the relationship b = a × cosθ. Based on this relationship, welding depth a may be converted to welding depth b.

[0041] 5. Other processes As shown in Figure 5, if the laminate 10 has an insert 6, the method for manufacturing the energy storage module in this disclosure may include a through-hole forming step after the determination step described above, by removing the insert 6 from the laminate 10 to form through-holes that penetrate the inside and outside of the laminate 10.

[0042] The method for manufacturing an energy storage module in this disclosure may include an electrolyte supply step, after the through-hole formation step described above, in which an electrolyte is supplied to the interior of the laminate through the through-holes. The method for supplying the electrolyte is not particularly limited, and known methods can be used. Furthermore, the method for manufacturing an energy storage module in this disclosure may include a sealing step, after the electrolyte supply step described above, in which the through-holes are sealed. The method for sealing the through-holes is not particularly limited, but for example, a method of sealing the through-holes using a film can be used.

[0043] 6. Energy storage module Specific examples of energy storage modules in this disclosure include secondary batteries (e.g., lithium-ion secondary batteries) and electric double-layer capacitors. Applications of energy storage devices include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), gasoline cars, and diesel cars. In particular, they are preferably used as power sources for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or battery electric vehicles (BEVs). Furthermore, energy storage devices in this disclosure may be used as power sources for mobile devices other than vehicles (e.g., railways, ships, aircraft), or as power sources for electrical products such as information processing devices.

[0044] This disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of this disclosure and achieves similar effects is included within the technical scope of this disclosure. [Explanation of Symbols]

[0045] 1... Current collector 2...Cathode active material layer 3...Negative electrode active material layer 4... Separator 5…Frame body 10…Laminate 20…Restraining member 30…Radiant heater 40...X-ray inspection equipment

Claims

1. A preparation step of preparing a laminate comprising an electrode sheet having an electrode having a current collector and an active material layer, and a resin frame arranged along the outer edge of the current collector, wherein a plurality of the electrode sheets are stacked in the thickness direction, A heating step of heating the frame in the laminate and welding adjacent frame in the thickness direction to form a welded portion, An inspection step in which a transparent inspection is performed on the corner of the laminate to check for variations in the welding depth at the welded portion, A determination step to determine whether a product is good or defective based on the variation in welding depth, It has, In the determination step, if the minimum value of the welding depth in the normal direction of the side surface of the frame is 1 mm or more, the product is determined to be a good product. A method for manufacturing energy storage modules.

2. The method for manufacturing an energy storage module according to claim 1, wherein in the inspection step, an X-ray inspection device is used to perform a translucent inspection of the corners of the laminate.

3. The method for manufacturing an energy storage module according to claim 2, wherein, when viewed from the thickness direction, the angle between the X-ray irradiation direction and the extension direction of the side surface of the frame is 30° or more and 60° or less.

4. The method for manufacturing an energy storage module according to claim 1, wherein the electrode sheet has a bipolar electrode as the electrode.

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