Electricity storage module manufacturing method and electricity storage module

Abstract

To provide a method for manufacturing a power storage module having good sealing property.SOLUTION: A method for manufacturing a power storage module includes: a preparation step of preparing a laminate in which a plurality of electrode sheets having electrodes having current collectors and active substance layers, and resin-made frame bodies arranged on the outer edges of the electrodes are laminated in a first direction; an arrangement step of arranging a pair of restraining members having thermal conductivity of 1 W / m k or less at positions overlapping the frame bodies in the laminate when viewed from the first direction; and a heating step of heating the frame bodies in the laminate and the pair of restraining members while applying a restraining pressure to the laminate by the pair of restraining members, welding the adjacent frame bodies in the first direction, and forming a seal part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In a method for manufacturing an electric storage module such as a secondary battery, a technique is known in which the side surfaces of a stack of multiple stacked electrode sheets are heated to seal the stack. For example, Patent Document 1 discloses a method for manufacturing an electric storage module, which includes a stacking step of stacking multiple bipolar electrode units, each having a frame joined to the peripheral edge of each electrode plate of multiple bipolar electrodes, via separators, and a heat welding step of heat welding sealing end faces formed by the peripheral end faces of the frame bodies adjacent in the stacking direction of the stack. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-174079 Summary of the Invention [Problem to be solved by the invention]

[0004] When heating the side surfaces of a stack of multiple electrode sheets, it is assumed that a pair of restraining members is used to apply a restraining pressure to the stack in order to make the thickness of the stack as small as possible from the viewpoint of volumetric energy density. For example, if the restraining members are made of a metal material, since metal materials have high thermal conductivity, when the side surfaces of the stack are heated, part of the heat applied to the side surfaces of the stack is conducted to the restraining members, which tends to result in insufficient sealing.

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

[0006] [1] a preparation step of preparing a laminate in which a plurality of electrode sheets are stacked in a first direction, the electrode sheets including electrodes each having a current collector and an active material layer, and a resin frame disposed along an outer edge of the electrode; a placement step of placing a pair of restraint members having a thermal conductivity of 1 W / m K or less at positions on the stack that overlap with the frame when viewed from the first direction; a heating step of heating the frame bodies of the stack and the pair of restraint members while applying a restraining pressure to the stack body with the pair of restraint members, thereby welding the frame bodies adjacent to each other in the first direction and forming a seal portion; A method for manufacturing an electricity storage module having the above structure.

[0007] [2] The method for manufacturing an electricity storage module according to [1], wherein the restraining member has a heat resistance temperature of 200°C or higher.

[0008] [3] The method for manufacturing an electricity storage module according to [1] or [2], wherein the thermal conductivity of the restraining member is 0.1 W / m·K or less.

[0009] [4] The method for manufacturing an electricity storage module according to any one of [1] to [3], wherein the material of the restraining member is an inorganic material.

[0010] [5] The method for manufacturing an electricity storage module according to any one of [1] to [3], wherein the material of the restraining member is resin.

[0011] [6] The method for manufacturing an electric storage module according to any one of [1] to [5], wherein in the heating step, the sealing portion of the laminate and the pair of restraint members are heated by a radiant heater.

[0012] [7] The method for producing an electricity storage module according to [6], wherein the radiant heater is an infrared lamp heater.

[0013] [8] A method for manufacturing a storage module described in any one of [1] to [7], wherein the shape of the stack when viewed from the first direction is rectangular, and the length of each side constituting the rectangle is 30 cm or more.

[0014] [9] an electrode assembly in which a plurality of electrodes, each having a current collector and an active material layer, are stacked in a first direction; a resin seal portion disposed along the outer edge of the electrode body; A storage module having A storage module in which, when the length of the sealing portion extending from the side surface of the sealing portion toward the electrode in a second direction perpendicular to the first direction is A, the length of the sealing portion at one end of the sealing portion in the first direction is A1, the length of the sealing portion at the other end of the sealing portion in the first direction is A2, and the length of the sealing portion at the center of the sealing portion in the first direction is A3, A1 and A2 are larger than A3. [Effects of the Invention]

[0015] The method for manufacturing an electricity storage module according to the present disclosure has the effect of obtaining an electricity storage module with good sealing properties. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic cross-sectional view illustrating a laminate according to the present disclosure. [Figure 2] FIG. 2 is an exploded view of the laminate shown in FIG. [Figure 3] 10A to 10C are schematic cross-sectional views illustrating a placement step and a heating step in the present disclosure. [Figure 4] 1 is a schematic cross-sectional view illustrating the effects of the present disclosure. [Figure 5] 1 is a schematic plan view illustrating a laminate according to the present disclosure. [Figure 6] 10A to 10C are schematic cross-sectional views illustrating an arrangement step in the present disclosure. [Figure 7] FIG. 10 is a schematic plan view illustrating a heating step in the present disclosure. [Figure 8] 1 is a schematic cross-sectional view illustrating an example of an energy storage module according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present disclosure will be described in detail 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 for ease of understanding. Furthermore, in this specification, when expressing the manner in which another member is disposed relative to a certain member, the term "above" or "below" simply refers to both a case in which another member is disposed directly above or below the certain member so as to be in contact with the certain member, and a case in which another member is disposed above or below the certain member via another member, unless otherwise specified.

[0018] A. Energy storage module manufacturing method Fig. 1 is a schematic cross-sectional view illustrating a laminate in the present disclosure, and Fig. 2 is an exploded view of the laminate shown in Fig. 1. Also, Fig. 3 is a schematic cross-sectional view illustrating the arrangement step and the heating step in the present disclosure.

[0019] As shown in FIGS. 1 and 2, in this disclosure, a laminate L is first prepared (preparation step). As shown in FIG. 2, the laminate L has a structure in which multiple electrode sheets ES are stacked in a first direction D1. The electrode sheet ES includes a current collector 1 and an electrode E having active material layers (positive electrode active material layer 2, negative electrode active material layer 3) disposed on the current collector 1. The laminate L shown in FIG. 2 includes, as electrode sheets ES, (i) an electrode sheet having a bipolar electrode BP as the electrode E, (ii) an electrode sheet having a positive electrode end electrode CA as the electrode E, and (iii) an electrode sheet having a negative electrode end electrode AN as the electrode E. Furthermore, as shown in FIG. 2, the electrode sheet ES has a resin frame 5 disposed along the outer edge of the electrode E (current collector 1).

[0020] As shown in FIG. 3, a pair of restraining members 20 (20a, 20b) are placed in positions overlapping with the frame bodies 5 of the stacked body L when viewed from the first direction D1 (placement process). One feature of the present disclosure is that the thermal conductivity of the restraining members 20 is low. Next, while applying a restraining pressure to the stacked body L with the pair of restraining members 20, a radiant heater 30 is used to heat the frame bodies 5 of the stacked body L and the pair of restraining members 20, welding the frame bodies 5 adjacent to each other in the first direction D1 and forming a seal portion SP.

[0021] In the present disclosure, a restraining member with low thermal conductivity is used, and by heating the frame and the restraining member, a power storage module with good sealing properties is obtained. As described above, when heating the side surface of a stack in which multiple electrode sheets are stacked, it is assumed that a pair of restraining members is used to apply a restraining pressure to the stack in order to reduce the thickness of the stack as much as possible from the perspective of volumetric energy density. By applying the restraining pressure to the stack, adjacent frame bodies in the first direction are crushed, thereby reducing the thickness of the stack.

[0022] For example, if the restraining member is made of a metal material, the high thermal conductivity of the metal material will cause some of the heat applied to the side surface SS of the laminate L to be conducted toward the restraining member when the side surface of the laminate is heated, resulting in insufficient sealing. Here, as shown in FIG. 4(a), the length of the seal portion SP extending from the side surface SS of the seal portion SP toward the electrode E in a second direction D2 perpendicular to the first direction D1 is defined as A. Also, the length of the seal portion SP at one end t1 of the seal portion SP in the first direction D1 is defined as A1, the length of the seal portion SP at the other end t2 of the seal portion SP in the first direction D1 is defined as A2, and the length of the seal portion SP at the center c of the seal portion SP in the first direction D1 is defined as A3. As shown in FIG. 4(a), if the restraining member is made of a metal material, the high thermal conductivity of the metal material will cause some of the heat applied to the side surface SS of the laminate L to be conducted toward the restraining member. As a result, A1 and A2 become smaller than A3, resulting in insufficient sealing at the ends t1 and t2.

[0023] In contrast, in the present disclosure, a restraining member with low thermal conductivity is used, and the frame and restraining member are heated. This prevents a portion of the heat applied to the side surface of the stack from being conducted to the restraining member, resulting in an energy storage module with excellent sealing properties. Furthermore, by adjusting the heating conditions (for example, by increasing the heating temperature or lengthening the heating time), a portion of the heat applied to the side surface of the restraining member can be conducted to the stack. This allows A1 and A2 to be larger than A3, as shown in FIG. 4(b), for example. Because end t1 and end t2 are positions that are prone to external stress, improving the sealing properties therein results in an energy storage module with excellent durability.

[0024] 1.Preparation process The preparation process in the present disclosure is a process of preparing a laminate in which a plurality of electrode sheets are stacked in a first direction, each electrode sheet having an electrode with a current collector and an active material layer, and a resin frame body arranged along the outer edge of the electrode.

[0025] (1) Electrode sheet The electrode sheet includes an electrode having a current collector and an active material layer, and a resin frame disposed along the outer edge of the electrode. The electrode includes 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 include an active material layer on each side of the current collector.

[0026] 2, the electrode sheet ES may have, as the 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 the 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.

[0027] 2, 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.

[0028] As shown in FIG. 2, the electrode sheet ES has a resin frame 5 arranged along the outer edge of the electrode E. The resin used for the frame 5 is, for example, a thermoplastic resin. Examples of thermoplastic resins include polyolefin resins such as polyethylene and polypropylene. When the electrode sheet ES is viewed from the first direction D1, the frame 5 is usually arranged along the entire outer edge of the electrode E (current collector 1). The frame 5 is used to form a sealing portion, which will be described later, and prevents leakage of the electrolyte. For example, if the outer edge of the electrode E (current collector 1) is rectangular, the frame 5 is arranged along the entire outer edge of the rectangle. Furthermore, as shown in FIG. 2, the frame 5 preferably covers a portion of one main surface p of the current collector 1, a portion 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.

[0029] (2) Laminate As shown in FIGS. 1 and 2, the laminate L has a plurality of electrode sheets ES stacked in a first direction D1. Furthermore, as shown in FIG. 1, the laminate L may have a plurality of power generation units U (U1, U2, U3) stacked in the first direction D1. A power generation unit typically includes a positive electrode active material layer, a separator, and a negative electrode active material layer. As will be described later, the power generation units function as a battery when an electrolyte is supplied to them. As shown in FIG. 1, the power generation units U (U1, U2, U3) may be connected in series with each other. Furthermore, although not specifically shown, the power generation units may be connected in parallel with each other.

[0030] In FIG. 1, power generation unit U1 has a positive electrode active material layer 2 in bipolar electrode BP1, a negative electrode active material layer 3 in negative electrode end electrode AN, and a separator 4 disposed therebetween. Power generation unit U2 has a positive electrode active material layer 2 in bipolar electrode BP2, a negative electrode active material layer 3 in bipolar electrode BP1, and a separator 4 disposed therebetween. Thus, two adjacent bipolar electrodes may form one power generation unit. Power generation unit U3 has a positive electrode active material layer 2 in positive electrode end electrode CA, a negative electrode active material layer 3 in bipolar electrode BP2, and a separator 4 disposed therebetween.

[0031] The shape of the stack when viewed from the first direction (shape in plan view) is not particularly limited, and examples thereof include quadrilaterals such as squares and rectangles. For example, the shape in plan view of the stack L shown in FIG. 5 is quadrilateral. The length of each side constituting the shape in plan view of the stack 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 sides is, for example, 200 cm or less. The larger the stack, the more difficult it is to control the sealing performance. In the present disclosure, even when the stack is large, a power storage module with good sealing performance can be obtained by using a restraining member with low thermal conductivity and heating the frame and the restraining member.

[0032] As shown in FIG. 5, the stack L may have a nest 6. One end of the nest 6 is present inside the stack L (the space between the power generation units), and the other end of the nest 6 is present outside the stack L. The nest 6 is arranged to extend in a second direction D2 perpendicular to the first direction D1. After the heating step described below, the nest 6 is removed to form a through-hole for supplying an electrolyte to each power generation unit. Although not particularly shown, the stack may have a voltage detection terminal extending in the second direction D2 for detecting the voltage of each power generation unit.

[0033] The method for producing the laminate is not particularly limited. As shown in FIG. 2, 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 arranged to face each other with a separator 4 interposed therebetween. At this time, another frame 5 (spacer 51) is disposed 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 arranged to face each other with a separator 4 interposed therebetween. At this time, another frame 5 (spacer 51) is disposed 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 arranged to face 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 way, the laminate L is obtained.

[0034] 2.Placement process The disposing step in the present disclosure is a step of disposing a pair of restraining members having a thermal conductivity of 1 W / m K or less at positions on the stack that overlap with the frame body in the first direction. Specifically, as shown in Fig. 6, a pair of restraining members 20 (20a, 20b) are disposed at positions on the stack L that overlap with the frame body 5 when viewed from the first direction D1.

[0035] The thermal conductivity of the restraint member is typically 1 W / m·K or less, and may be 0.5 W / m·K or less, 0.3 W / m·K or less, or 0.1 W / m·K or less. For example, if the restraint member is made of a metal, the thermal conductivity is greater than 1 W / m·K. For example, the thermal conductivity of stainless steel is 16 W / m·K, and the thermal conductivity of aluminum is 236 W / m·K.

[0036] The thermal conductivity of the restraint member may be lower than that of the resin frame. For example, if the frame is made of polyethylene, the thermal conductivity of the frame is, for example, 0.33 W / m K (low-density PE) to 0.52 W / m K (high-density PE).

[0037] The heat resistance temperature of the restraining member is usually higher than the melting point of the resin frame. Furthermore, the heat resistance temperature of the restraining member is higher than the heating temperature in the heating process described below. If the heat resistance temperature of the restraining member is lower than the melting point of the resin frame or the heating temperature in the heating process, sufficient heating cannot be performed. The heat resistance temperature of the restraining member refers to the temperature at which the restraining member will not be burned. In other words, it refers to the temperature at which the restraining member can maintain its restraining function. For example, if the material of the restraining member is an inorganic material, the melting point of the material may be considered the heat resistance temperature. Furthermore, for example, if the material of the restraining member is resin, the deflection temperature under load of the material may be considered the heat resistance temperature.

[0038] The heat resistance temperature of the restraining member is, for example, 200°C or higher, or alternatively, 250°C or higher, or 350°C or higher. The high heat resistance temperature of the restraining member allows the frame body to be heated sufficiently. Furthermore, there is no particular upper limit to the heat resistance temperature of the restraining member.

[0039] Examples of materials for the restraint member include inorganic materials and resins. Examples of inorganic materials include ceramics such as alumina and silica, glass, gypsum, brick, calcium silicate, and concrete. Examples of the resins include polyphenylene sulfide (PPS)-based resins, polyether ether ketone (PEEK)-based resins, polytetrafluoroethylene (PTFE)-based resins, polyamide-imide (PAI)-based resins, polyimide (PI)-based resins, polyethersulfone (PES)-based resins, polyethernitrile (PEN)-based resins, polybenzimidazole (PBI)-based resins, polyetherimide (PEI)-based resins, and polyarylate (PAR)-based resins.

[0040] 3.Heating process The heating process in the present disclosure is a process of heating the frame body in the stack and the pair of restraint members while applying a restraint pressure to the stack with the pair of restraint members, welding the frame bodies adjacent in the first direction and forming a seal portion.

[0041] The restraining pressure applied to the laminate by the restraining members is not particularly limited, but may be, for example, 1 kPa to 30 MPa, or 0.1 MPa to 10 MPa, and can be adjusted, for example, by clamps connected to the pair of restraining members.

[0042] In the heating process, the frame body and the pair of restraining members in the laminate are heated to weld adjacent frame bodies in the first direction. That is, not only the frame body but also the restraining members are heated. Conventionally, the frame body has been heated while avoiding the restraining members to prevent burnout of the restraining members. In contrast, in the present disclosure, by using restraining members with a high heat resistance temperature, not only the frame body but also the restraining members are heated. When viewed from a second direction perpendicular to the first direction, the heat amount applied per unit area of ​​the frame body is Q1 and the heat amount applied per unit area of ​​the restraining members is Q2, the ratio of Q2 to Q1 (Q2 / Q1) is, for example, 0.3 or more, or alternatively 0.5 or more, 0.7 or more, or 0.9 or more.

[0043] In the present disclosure, the side surfaces (surfaces extending in the first direction) of the frame bodies are typically heated to weld adjacent frame bodies in the first direction and form a seal. The heating temperature is appropriately selected depending on the material of the frame bodies, but may be, for example, 120°C or higher and 300°C or lower, or 150°C or higher and 250°C or lower. Heating is performed using a radiant heater such as an infrared lamp heater. For example, as shown in FIG. 3, a radiant heater 30 is used to heat the side surfaces SS of the frame body 5 and the pair of restraining members 20 (20a, 20b). The output of each infrared lamp is, for example, 100 W or higher, and may be 150 W or higher, or 300 W or higher.

[0044] 7, air may be blown toward the laminate L using an air blower 40 arranged on the opposite side of the laminate L from the radiant heater 30. By blowing air, for example, even if multiple nesting pieces protrude from the side of the frame, it is possible to prevent air from stagnating between the multiple nesting pieces, thereby suppressing the occurrence of uneven heating. The temperature of the air blown out from the air blower 40 may be room temperature, 50°C or higher, 100°C or higher, or 150°C or higher.

[0045] As shown in FIG. 4(b), the length of the seal portion SP extending from the side surface SS of the seal portion SP toward the electrode E in a second direction D2 perpendicular to the first direction D1 is defined as A. The length A of the seal portion SP can be determined, for example, by observing a cross section of the seal portion SP. Furthermore, the length of the seal portion SP at one end t1 of the seal portion SP in the first direction D1 is defined as A1, the length of the seal portion SP at the other end t2 of the seal portion SP in the first direction D1 is defined as A2, and the length of the seal portion SP at the center c of the seal portion SP in the first direction D1 is defined as A3. As shown in FIG. 4(b), A1 and A2 are preferably greater than A3.

[0046] The ratio of A1 to A3 (A1 / A3) is, for example, 1.05 or more, or may be 1.2 or more, or may be 1.5 or more. Similarly, the ratio of A2 to A3 (A2 / A3) is, for example, 1.05 or more, or may be 1.2 or more, or may be 1.5 or more. Furthermore, as shown in FIG. 4(b), the side surface α of the seal portion SP on the electrode E side may be curved so that the outer side of the electrode E (the side opposite the center of the electrode E) is convex.

[0047] 4. Other processes As shown in FIG. 5, when the laminate L has a nest 6, the method for manufacturing an energy storage module in the present disclosure may include a through-hole forming step of forming a through-hole by removing the nest 6 from the laminate L after the heating step described above.

[0048] The method for manufacturing an electricity storage module according to the present disclosure may include, after the through-hole forming step, an electrolyte solution supplying step of supplying an electrolyte solution into the laminate through the through-holes. The method for supplying the electrolyte solution is not particularly limited, and a known method may be used.

[0049] The method for manufacturing an electricity storage module according to the present disclosure may include a sealing step of sealing the through-holes after the electrolyte solution supplying step. The method for sealing the through-holes is not particularly limited, and examples thereof include a method of sealing the through-holes using a film.

[0050] 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. Furthermore, 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-powered vehicles, and diesel-powered vehicles. It is particularly preferred that the power storage device be used as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). Furthermore, the power storage device in the present disclosure may be used as a power source for mobile objects other than vehicles (e.g., trains, ships, and aircraft), or as a power source for electrical appliances such as information processing devices.

[0051] B. Energy storage module FIG. 8 is a schematic cross-sectional view illustrating an example of an energy storage module according to the present disclosure. The energy storage module 100 shown in FIG. 8 includes an electrode assembly 10 in which multiple electrodes E are stacked in a first direction D1, and a resin seal portion SP arranged along the outer edge of the electrode assembly 10. The interior of the electrode assembly 10, sealed by the seal portion SP, is filled with an electrolyte solution 7. As shown in FIG. 4(b), the length of the seal portion SP extending from the side surface SS of the seal portion SP toward the electrode E in a second direction D2 perpendicular to the first direction D1 is defined as A. The length of the seal portion SP at one end t1 of the seal portion SP in the first direction D1 is defined as A1, the length of the seal portion SP at the other end t1 of the seal portion SP in the first direction D1 is defined as A2, and the length of the seal portion SP at the center c of the seal portion SP in the first direction D1 is defined as A3. As shown in FIG. 4(b), A1 and A2 are greater than A3.

[0052] According to the present disclosure, A1 and A2 are larger than A3, resulting in an energy storage module with good sealing properties and durability. The energy storage module according to the present disclosure is similar to the content described above in "A. Method for manufacturing an energy storage module," and therefore will not be described here.

[0053] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure. [Explanation of symbols]

[0054] 1...Current collector 2...Cathode active material layer 3...Negative electrode active material layer 4...Separator 5…Frame body 10...Electrode body 20...Restraining member 30…Radiant heater 100... Energy storage module

Claims

1. a preparation step of preparing a laminate in which a plurality of electrode sheets are stacked in a first direction, the electrode sheets including electrodes each having a current collector and an active material layer, and a resin frame disposed along an outer edge of the electrode; a placement step of placing a pair of restraint members having a thermal conductivity of 1 W / m K or less at positions in the stack that overlap with the frame body when viewed from the first direction; a heating step of heating the frame bodies of the stack and the pair of restraining members while applying a restraining pressure to the stack by the pair of restraining members, thereby welding the frame bodies adjacent to each other in the first direction and forming a seal portion; and In the heating step, the confining pressure is applied only to the frame portion of the stack.

2. The method for manufacturing an electric storage module according to claim 1 , wherein the restraining member has a heat-resistant temperature of 200° C. or higher.

3. The method for manufacturing an electric storage module according to claim 1 , wherein the thermal conductivity of the restraining member is 0.1 W / m·K or less.

4. The method for manufacturing an electric storage module according to claim 1 , wherein the material of the restraining member is an inorganic material.

5. The method for manufacturing an electric storage module according to claim 1 , wherein the material of the restraining member is resin.

6. The method for manufacturing an electric storage module according to claim 1 , wherein in the heating step, the seal portion of the stack and the pair of restraint members are heated by a radiant heater.

7. The method for manufacturing an electric storage module according to claim 6 , wherein the radiant heater is an infrared lamp heater.

8. The method for manufacturing an energy storage module according to claim 1 , wherein the shape of the stack when viewed from the first direction is a rectangle, and each side of the rectangle has a length of 30 cm or more.

9. an electrode assembly in which a plurality of electrodes, each having a current collector and an active material layer, are stacked in a first direction; a resin seal portion disposed along the outer edge of the electrode body; A storage module having When the energy storage module is viewed from a side, a plurality of welded portions are observed in the seal portion in the first direction, an energy storage module in which, when a length of the sealing portion extending from a side surface of the sealing portion toward the electrode in a second direction perpendicular to the first direction is defined as A, a length of the sealing portion at one end of the sealing portion in the first direction is defined as A1, a length of the sealing portion at the other end of the sealing portion in the first direction is defined as A2, and a length of the sealing portion at a center of the sealing portion in the first direction is defined as A3, A1 and A2 are greater than A3.

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