Manufacturing method of power storage module

Abstract

To provide a manufacturing method of a power storage module that can obtain a power storage module with excellent sealing performance.SOLUTION: A manufacturing method includes: a step of preparing a laminate 10 that comprises multiple electrode sheets which are stacked in a thickness direction and each of which includes one or the other of electrodes having a current collector 1 and one or the other of active material layers, and also includes resin frame bodies 5 arranged along an outer edge of the current collector 1; a restraining step of arranging a pair of restraint members 20 at positions overlapping the frame bodies 5 in the laminate 10 when viewed from the thickness direction, and restraining the frame bodies 5 in the thickness direction by the pair of restraint members 20; and a heating step of radiation-heating, using radiant heaters 30, side surfaces of the frame bodies 5 extending in the thickness direction, in the restrained frame bodies 5, to weld the frame bodies 5 adjacent to each other in the thickness direction, so as to form a welded part. Therein, the heating step includes inspecting, by an external inspection device 40, occurrence of smoke or scorching on the side surfaces of the frame bodies 5 while performing radiation-heating, and then, terminating radiation-heating on the basis of detection, by the external inspection device 40, of the occurrence of smoke or scorching.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing an energy storage module. [Background technology]

[0002] In a method for manufacturing a storage module such as a secondary battery, a seal member is provided on the outer edge of a plurality of stacked electrodes to seal the plurality of stacked electrodes. For example, Patent Document 1 discloses a storage module including an electrode stack and a seal member surrounding the electrode stack, the seal member having a primary seal provided on the periphery of a current collector and a secondary seal covering the primary seal. Patent Document 1 further discloses that the primary seals adjacent to each other in the stacking direction are welded to each other. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-22534 Summary of the Invention [Problem to be solved by the invention]

[0004] Sealing members such as a primary seal and a secondary seal are required to have good sealing properties. In Patent Document 1, primary seals (resin frame bodies) stacked along a first direction (thickness direction) are welded together. To obtain good sealing properties, the welded portion where the resin frame bodies are welded together needs to have a sufficient welding depth, but it is difficult to actually observe the welding depth. Therefore, if there are any places where the welding depth is insufficient, the sealing properties of the energy storage module may be reduced.

[0005] The present disclosure has been made in consideration of the above-described circumstances, and has as its main object to provide a manufacturing method for an electricity storage module, which is capable of obtaining an electricity storage module with excellent sealing properties. [Means for solving the problem]

[0006] [1] a preparation step of preparing a laminate including an electrode sheet having an electrode including a current collector and an active material layer, and a resin frame disposed along an outer edge of the current collector, the laminate being formed by stacking a plurality of the electrode sheets in a thickness direction; a restraining step of arranging a pair of restraining members at positions of the laminate overlapping with the frame body when viewed from the thickness direction, and restraining the frame body in the thickness direction with the pair of restraining members; a heating step of radiating heating a side surface of the restrained frame body extending in the thickness direction by a radiant heater to weld adjacent frames in the thickness direction to form a welded portion; having In the heating step, while performing the radiative heating, a visual inspection device is used to check for smoke or scorching on the side surface of the frame; The method for manufacturing an electricity storage module further comprises terminating the radiant heating based on detection of the occurrence of the smoke generation or the scorching by the appearance inspection device.

[0007] [2] The manufacturing method of an energy storage module described in [1], wherein the radiant heater is an infrared heater having a rated output of 2.8 kW or more and 5.6 kW or less, the distance between the side of the frame body and the radiant heater is 40 mm or more and 60 mm or less, and the restraining pressure applied to the frame body by the restraining member is 3 MPa or more and 32 MPa or less.

[0008] [3] The method for manufacturing an electricity storage module according to [1] or [2], wherein the resin constituting the frame is polyethylene.

[0009] [4] The method for manufacturing a storage module according to any one of [1] to [4], wherein the electrode sheet has a bipolar electrode as the electrode.

[0010] [5] The shape of the laminate as viewed in the thickness direction is quadrangular, The method for manufacturing a storage module according to any one of [1] to [4], wherein the length of each side constituting the rectangle is 30 cm or more. Effect of the Invention

[0011] The method for manufacturing an electricity storage module according to the present disclosure has the effect of making it possible to obtain an electricity storage module with excellent sealing properties. [Brief description of the drawings]

[0012] [Figure 1] 1A and 1B are a schematic plan view and a schematic cross-sectional view illustrating a laminate according to the present disclosure. [Diagram 2] 3A to 3C are schematic cross-sectional views illustrating a restraining step and a heating step in the present disclosure. [Diagram 3] FIG. 2 is a schematic cross-sectional view illustrating a frame (after a heating step) in the present disclosure. [Figure 4] FIG. 2 is a schematic plan view illustrating a laminate in the present disclosure. [Diagram 5] 1A to 1C are schematic cross-sectional views illustrating a preparation step in the present disclosure. [Figure 6] 1A to 1C are schematic plan views illustrating a heating step in the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The manufacturing method of the energy storage module in the present disclosure will be described in detail below with reference to the drawings. Each of the drawings shown below is a schematic illustration, and the size and shape of each part are appropriately exaggerated to facilitate understanding. In addition, in this specification, when expressing an aspect in which another member is arranged relative to a certain member, the term "above" or "below" simply refers to both a case in which another member is arranged directly above or below a certain member so as to be in contact with the certain member, and a case in which another member is arranged above or below a certain member via another member, unless otherwise specified.

[0014] The manufacturing method of the electricity storage module in the present disclosure includes a preparation step of preparing a laminate including an electrode sheet having an electrode having a current collector and an active material layer, and a resin frame body arranged along the outer edge of the current collector, and in which a plurality of the electrode sheets are stacked in a thickness direction; a restraining step of arranging a pair of restraining members at a position in the laminate that overlaps with the frame body when viewed from the thickness direction, and restraining the frame body in the thickness direction with the pair of restraining members; and a heating step of radiantly heating a side surface of the frame body extending in the thickness direction of the restrained frame body with a radiant heater, welding the frame bodies adjacent to each other in the thickness direction, and forming a welded portion, wherein while the radiant heating is being performed in the heating step, the side surface of the frame body is inspected for smoke or scorching using an appearance inspection device, and the radiant heating is terminated based on detection of the smoke or scorching by the appearance inspection device.

[0015] The preparation step in the present disclosure is a step 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 AA in 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 a thickness direction D1. The electrode sheet ES includes a current collector 1 and an electrode E having 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) includes, as the electrode sheets ES, (i) an electrode sheet having a bipolar electrode BP, (ii) an electrode sheet having a positive electrode end electrode CA, and (iii) an electrode sheet having a negative electrode end electrode AN. In addition, as shown in FIGS. 1(a) and 1(b), the electrode sheet ES has a resin frame 5 disposed along the outer edge of the current collector 1.

[0016] The restraining step and the heating step in the present disclosure will be described with reference to FIG. 2. In FIG. 2, a pair of restraining members 20 (20a, 20b) are arranged at a position overlapping with the frame body 5 in the laminate 10 as viewed in the thickness direction D1, and the pair of restraining members 20 (20a, 20b) restrain the frame body 5 in the thickness direction D1. Next, in the restrained frame body 5, the side surface SS of the frame body 5 extending in the thickness direction D1 is radiatively heated by the radiant heater 30. As a result, as shown in FIG. 3, the frame bodies 5 adjacent to each other in the thickness direction D1 are welded to form a welded portion 51. The frame body 5 after the heating step has the welded portion 51 and an unwelded portion 52 located closer to the electrode E than the welded portion 51. In the present disclosure, as shown in FIG. 2, while performing radiative heating by the radiant heater 30, the occurrence of smoke or scorching on the side surface SS of the frame body 5 is inspected by the appearance inspection device 40. Based on the detection of the occurrence of smoke or scorching by the appearance inspection device 40, the radiant heating by the radiant heater 30 is terminated.

[0017] According to the present disclosure, after radiant heating has begun, radiant heating can be terminated based on detection of smoke or scorching by a visual inspection device, thereby forming a welded portion with sufficient welding depth and obtaining an energy storage module with good sealing properties.

[0018] As described above, in order to obtain good sealing, it is necessary that the welded portion where the resin frame bodies are welded together has a sufficient weld depth, but it is difficult to actually observe the weld depth. For example, it is assumed that the weld depth is observed based on the change in color (resin color) of the frame body due to welding. However, since a pair of restraining members is disposed at both ends of the frame body in the stacking direction, it is difficult to judge the weld depth by observing the change in color of the frame body in the stacking direction of the frame body while performing radiant heating.

[0019] Also, instead of observing the welding depth, a method is envisaged in which the surface temperature of the side of the frame is measured and the welding depth is estimated from the surface temperature. However, when radiant heating is being performed, the side of the frame is affected by the radiant heating, making it difficult to accurately measure the surface temperature of the side of the frame. Even if the surface temperature of the side of the frame is measured immediately after the end of radiant heating, it is easily affected by the atmosphere (especially the temperature) during the heating process, making it difficult to accurately measure the surface temperature of the side of the frame.

[0020] In contrast, in the present disclosure, while performing radiant heating, the side surface of the frame body is inspected for smoke generation or scorching by an appearance inspection device, and the radiant heating is terminated based on the detection of smoke generation or scorching by the appearance inspection device. For example, by controlling the radiant heating conditions and the restraining pressure applied to the frame body by the restraining member, the temperature in the welding depth direction at the timing of smoke generation or scorching occurrence (i.e., the timing when the surface temperature of the side surface of the frame body becomes equal to or higher than a threshold value) can be controlled. Therefore, by terminating the radiant heating based on the detection of smoke generation or scorching by the appearance inspection device, it is possible to determine that a welding part having a sufficient welding depth has been formed, and a storage module with good sealing properties can be obtained. In addition, since it is possible to determine that a welding part having a sufficient welding depth has been formed while performing radiant heating, rather than after the end of radiant heating, productivity is good.

[0021] 1. Preparation process The preparation process in the present disclosure is a process 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, and in which a plurality of the electrode sheets are stacked in the thickness direction.

[0022] (1) Electrode sheet The electrode sheet has 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 has 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 have an active material layer on each of both sides of the current collector.

[0023] 1(b), the electrode sheet ES may have, as an electrode E, a bipolar electrode having a current collector 1, a positive electrode active material layer disposed on one surface of the current collector 1, and a negative electrode active material layer disposed on one surface of the current collector 1. Although not particularly shown, the electrode sheet may have, as an electrode, an electrode in which a positive electrode active material layer is disposed on each of both surfaces of the current collector, or an electrode in which a negative electrode active material layer is disposed on each of both surfaces of the current collector.

[0024] 1(b), the electrode sheet ES may have, as the electrode E, a positive electrode end electrode CA having a current collector 1 and a positive electrode active material layer 2 disposed on one surface of the current collector 1. The electrode sheet ES may also have, as the electrode E, a negative electrode end electrode AN having a current collector 1 and a negative electrode active material layer 3 disposed on one surface of the current collector 1.

[0025] As shown in FIGS. 1(a) and 1(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 the thermoplastic resin include polyolefins such as polyethylene and polypropylene. Examples of the polyethylene include high density polyethylene (HDPE). The density of high density polyethylene is, for example, 0.94 g / cm. 3 More than 0.973g / cm 3 The melting point of the thermoplastic resin is, for example, 120° C. or higher and 140° C. or lower.

[0026] When the electrode sheet ES is viewed from the thickness direction, the frame 5 is usually disposed along the entire outer periphery of the current collector 1. The frame 5 is used to form a welded portion (seal portion) described later, and the welded portion prevents leakage of the electrolyte. For example, when the outer periphery of the current collector 1 is rectangular, the frame 5 is disposed along the entire outer periphery of the rectangle. Furthermore, as shown in FIG. 5 described later, the frame 5 preferably 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 constituting the outer periphery of the current collector 1.

[0027] (2) Laminate As shown in Figs. 1(a) and 1(b), the laminate 10 has a plurality of electrode sheets ES stacked in the thickness direction D1. Also, as shown in Fig. 1(b), the laminate 10 may have a plurality of power generation units U (U1, U2, U3) stacked in the thickness direction D1. The 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 the power generation unit. As shown in Fig. 1(b), the power generation units U (U1, U2, U3) may be connected in series with each other. Also, although not particularly shown, the power generation units may be connected in parallel with each other.

[0028] In FIG. 1(b), the generating 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 disposed therebetween. The generating 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 disposed therebetween. In this manner, one generating unit may be constituted by two adjacent bipolar electrodes. The generating 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 disposed therebetween.

[0029] The shape of the laminate viewed from the thickness direction (planar shape) is not particularly limited, and examples thereof include quadrangles such as squares and rectangles. For example, the planar shape of the laminate 10 shown in FIG. 1 is a quadrangle. The length of each side constituting the planar shape of the laminate is not particularly limited, and may be, for example, 30 cm or more, 50 cm or more, or 100 cm or more. Meanwhile, the length of each of the above sides is, for example, 200 cm or less. The larger the laminate, the more difficult it is to manage the sealing property. In the present disclosure, even if the laminate is large, a storage module with good sealing property can be obtained by performing a heating process described later.

[0030] As shown in FIG. 4, the laminate 10 may have a nest 6. One end t1 of the nest 6 is present inside the laminate 10, and the other end t2 of the nest 6 is present outside the laminate 10. The nest 6 is disposed so as to extend in a direction perpendicular to the thickness direction. After the heating step described later, the nest 6 is removed to form a through hole for supplying an electrolyte to each power generation unit. Although not particularly shown, the laminate may have a voltage detection terminal extending in a direction perpendicular to the thickness direction for detecting the voltage of each power generation unit.

[0031] The method of producing the laminate is not particularly limited. As shown in FIG. 5, the negative electrode active material layer 3 in the bipolar electrode BP1 and the positive electrode active material layer 2 in the bipolar electrode BP2 are opposed to each other with a separator 4 interposed therebetween. At this time, another frame 5 (spacer 51) is arranged between the frame 5 in the bipolar electrode BP1 and the frame 5 in the bipolar electrode BP2. Similarly, the positive electrode active material layer 2 in the bipolar electrode BP1 and the negative electrode active material layer 3 in the negative electrode end electrode AN are opposed to each other with a separator 4 interposed therebetween. At this time, another frame 5 (spacer 51) is arranged between the frame 5 in the bipolar electrode BP1 and the frame 5 in the negative electrode end electrode AN. Similarly, the negative electrode active material layer 3 in the bipolar electrode BP2 and the positive electrode active material layer 2 in the positive electrode end electrode CA are opposed to each other with a separator 4 interposed therebetween. At this time, another frame 5 (spacer 51) is placed between the frame 5 of the bipolar electrode BP2 and the frame 5 of the positive end electrode CA. In this manner, the laminate 10 is obtained.

[0032] 2.Restraint process The restraint process in the present disclosure is a process of placing a pair of restraint members at a position in the laminate that overlaps with the frame body when viewed from the thickness direction, and restraining the frame body in the thickness direction with the pair of restraint members.

[0033] 2, a pair of restraining members 20 (20a, 20b) are disposed at positions overlapping with the frame body 5 in the laminate 10 when viewed from the thickness direction D1, and the pair of restraining members 20 (20a, 20b) restrain the frame body 5 in the thickness direction D1. By restraining the frame body 5 with the pair of restraining members 20 (20a, 20b), adjacent frame bodies 5 can be welded with good sealing properties in a heating step described later. The restraining pressure applied to the frame bodies by the restraining members is not particularly limited, and may be, for example, 3 MPa or more and 32 MPa or less, and may be 5 MPa or more and 30 MPa or less.

[0034] 3.Heating process The heating process in the present disclosure is a process in which the side surface of the restrained frame body extending in the thickness direction is radiatively heated by a radiant heater to weld adjacent frame bodies in the thickness direction and form a welded portion.

[0035] Examples of the radiant heater include an infrared heater (IR heater). The surface temperature of the heating body in the radiant heater is not particularly limited, but is, for example, 1200°C or more and 2100°C or less. The maximum energy wavelength in the radiant heater is not particularly limited, but is, for example, 1.2 μm or more and 1.7 μm or less. The rated output of the infrared heater is preferably 2.8 kW or more and 5.6 kW or less. The operating voltage of the infrared heater may be 200 V. The infrared heater may be a single-phase heater or a three-phase heater. Examples of the connection method in the three-phase heater include delta connection, star connection, and V connection. The current value in the infrared heater varies depending on the type of heater (single-phase heater or three-phase heater) and the connection method in the three-phase heater, but is, for example, 8 A or more and 12 V or less.

[0036] As shown in Fig. 2, the radiant heater 30 is disposed with a space provided with respect to the side surface SS of the frame body 5. The distance between the side surface SS of the frame body 5 and the radiant heater 30 is not particularly limited, but is, for example, 40 mm or more and 60 mm or less. Also, as shown in Fig. 6, it is preferable that the multiple radiant heaters 30 are disposed along a direction D3 perpendicular to a normal direction D2 of the side surface SS of the frame body 5 when viewed from the thickness direction D1.

[0037] In the heating process, while performing radiation heating, the appearance inspection device inspects the side of the frame for smoke or scorching. When radiation heating is performed on the side of the frame, the surface temperature of the side of the frame gradually rises, and then, when the surface temperature of the side of the frame reaches the smoke temperature, smoke occurs from the surface of the side of the frame. When the surface temperature of the side of the frame further rises, scorching occurs on the surface of the side of the frame. For example, when the resin constituting the frame is high density polyethylene (HDPE), smoke occurs when the surface temperature of the side of the frame reaches 246°C. In the present disclosure, by controlling the restraint conditions and heating conditions, the temperature in the welding depth direction when the surface temperature reaches the temperature at which smoke occurs can be controlled. In addition, it can be confirmed by a preliminary experiment that the target welding depth has been achieved when welding is completed by smoke detection.

[0038] The appearance inspection device includes, for example, a camera that photographs the side surface of the frame body, and an image sensor that processes the image photographed by the camera. The image sensor is configured to determine whether or not smoke has been generated or whether or not scorching has occurred on the side surface of the frame body. As shown in FIG. 2, the appearance inspection device 40 is disposed at a position that does not interfere with radiant heating by the radiant heater 30, and photographs the side surface SS of the frame body 5. As shown in FIG. 6, it is preferable that a plurality of appearance inspection devices 40 are disposed along a direction D3 perpendicular to a normal direction D2 of the side surface SS of the frame body 5 as viewed from the thickness direction D1.

[0039] In the heating step, the radiation heating is terminated based on the detection of smoke generation or scorching by the appearance inspection device. In particular, it is preferable to terminate the radiation heating after the detection of smoke generation and before the detection of scorching, because this can prevent appearance defects caused by scorching. In addition, when the radiation heating is terminated based on the detection of scorching, the scorching may be removed after the heating step, for example, by polishing.

[0040] The heating step is usually performed on the entire periphery of the laminate. For example, when the laminate has a rectangular outer edge as viewed in the thickness direction, the heating step is usually performed on all four sides. As shown in FIG. 3, the welding depth in the normal direction D2 of the side surface SS of the frame 5 is W. In the present disclosure, it is preferable that the welding depth W is 1 mm or more.

[0041] 4.Other processes As shown in FIG. 4, when the laminate 10 has a nest 6, the manufacturing method of the energy storage module in the present disclosure may include a through hole forming process in which, after the above-mentioned heating process, the nest 6 is removed from the laminate 10 to form a through hole penetrating the interior and exterior of the laminate 10.

[0042] The method for producing a storage module in the present disclosure may include, after the through-hole forming step described above, an electrolyte supplying step of supplying an electrolyte solution to the inside of the laminate through the through-hole. The method for supplying the electrolyte solution is not particularly limited, and a known method is used. In addition, the method for producing a storage module in the present disclosure may include, after the electrolyte supplying step described above, a sealing step of sealing the through-hole. The method for sealing the through-hole is not particularly limited, and an example of the method includes a method of sealing the through-hole using a film.

[0043] 5. Energy storage module Specific examples of the power storage module in the present disclosure include secondary batteries (e.g., lithium ion secondary batteries) and electric double layer capacitors. In addition, applications of the power storage device include, for example, power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline automobiles, and diesel automobiles. In particular, it is preferable to use the power storage device in the present disclosure as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). In addition, the power storage device in the present disclosure may be used as a power source for moving bodies other than vehicles (e.g., railways, ships, and aircraft), and may be used as a power source for electrical products such as information processing devices.

[0044] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits similar effects is included in the technical scope of the present 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...Appearance inspection device

Claims

1. a preparation step of preparing a laminate including an electrode sheet having an electrode including a current collector and an active material layer, and a resin frame disposed along an outer edge of the current collector, the laminate being formed by stacking a plurality of the electrode sheets in a thickness direction; a restraining step of arranging a pair of restraining members at positions of the laminate overlapping with the frame body when viewed from the thickness direction, and restraining the frame body in the thickness direction with the pair of restraining members; a heating step of radiating heating a side surface of the restrained frame body extending in the thickness direction by a radiant heater to weld adjacent frame bodies in the thickness direction and form a welded portion; having In the heating step, while performing the radiative heating, a visual inspection device is used to check for smoke or scorching on the side surface of the frame; The method for manufacturing an energy storage module further comprises terminating the radiant heating based on detection of the occurrence of smoke or scorching by the appearance inspection device.

2. 2. The method for manufacturing an energy storage module according to claim 1, wherein the radiant heater is an infrared heater having a rated output of 2.8 kW or more and 5.6 kW or less, a distance between a side surface of the frame body and the radiant heater is 40 mm or more and 60 mm or less, and a restraining pressure applied to the frame body by the restraining member is 3 MPa or more and 32 MPa or less.

3. The method for producing an electricity storage module according to claim 1 or 2, wherein the resin constituting the frame is polyethylene.

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

5. The shape of the laminate as viewed in the thickness direction is quadrangular, The method for manufacturing an electric storage module according to claim 1 or 2, wherein each of the sides constituting the rectangle has a length of 30 cm or more.

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