Method of manufacturing electrode, method of manufacturing power storage device and electrode

Abstract

To provide a method of manufacturing an electrode, with which an active material layer is prevented from being cracked after electromagnetic wave irradiation, the electrode and a method of manufacturing a power storage device.SOLUTION: A method of manufacturing an electrode includes steps of: forming, on a current collector, a composition layer comprising a composition containing an active material, a binder and a liquid medium; and irradiating the composition layer with electromagnetic waves to obtain an active material layer containing the active material and the binder. When the active material layer is divided into two regions in a thickness direction, a region X in contact with the current collector and a region Y not in contact with the current collector satisfy at least one of the following conditions (1) or (2). (1) The tap density of the active material contained in the region Y is smaller than the tap density of the active material contained in the region X. (2) The amount of the binder contained in the region Y is smaller than the amount of the binder contained in the region X.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an electrode, a method for manufacturing an electricity storage device, and an electrode. [Background technology]

[0002] Electricity storage devices such as lithium-ion secondary batteries use electrodes in which an active material layer containing an active material is formed on the surface of a current collector such as a metal foil. A known method for manufacturing such electrodes involves coating the surface of the current collector with a composition prepared by mixing an active material and a binder, which are components of the active material layer, with a liquid medium to form a coating film, and then removing the liquid medium from the coating film. As a method for removing the liquid medium contained in the coating film, a method has been proposed in which the coating film is irradiated with far infrared rays, which are electromagnetic waves with a wavelength that is highly absorbent by the liquid medium, to evaporate the liquid medium (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 06-063495 Summary of the Invention [Problem to be solved by the invention]

[0004] While the method of removing the liquid medium by irradiating the coating with electromagnetic waves can shorten the time required to dry the active material layer, it is prone to cracking the surface of the active material layer after drying. This is thought to be because the gas generated by the rapid evaporation of the liquid solvent applies force to the inside of the active material layer. Furthermore, cracks in the active material layer are likely to occur at the periphery of the electrode. This is thought to be because the temperature of the area of ​​the periphery of the current collector where the active material layer is not formed is likely to rise due to the irradiation of electromagnetic waves, which is likely to promote evaporation of the liquid medium contained in the coating. An object of one embodiment of the present disclosure is to provide a method for manufacturing an electrode, an electrode, and a power storage device, in which cracking of an active material layer after irradiation with electromagnetic waves is suppressed. [Means for solving the problem]

[0005] The means for solving the above problems include the following embodiments. <1> forming a composition layer on a current collector, the composition layer comprising a composition including an active material, a binder, and a liquid medium; and a step of irradiating the composition layer with electromagnetic waves to obtain an active material layer containing an active material and a binder, A method for manufacturing an electrode, wherein when the active material layer is divided into two regions in the thickness direction, a region X in contact with the current collector and a region Y not in contact with the current collector satisfy at least one of the following conditions (1) or (2): (1) The tap density of the active material in region Y is smaller than the tap density of the active material in region X. (2) The amount of binder contained in region Y is less than the amount of binder contained in region X. <2> The active material layer has a pore diameter of 1.1 μm or more, or a pore volume of 0.20 ml / g or more. <1> A method for producing the electrode described in <3> a current collector; and an active material layer containing an active material disposed on the current collector; An electrode, wherein when the active material layer is divided into two regions in the thickness direction, a region X in contact with the current collector and a region Y not in contact with the current collector satisfy at least one of the following conditions (1) or (2): (1) The tap density of the active material in region Y is smaller than the tap density of the active material in region X. (2) The amount of binder contained in region Y is less than the amount of binder contained in region X. <4> a negative electrode active material layer including a negative electrode active material and a positive electrode active material layer including a positive electrode active material, which are disposed on respective surfaces of the current collector; At least one of the negative electrode active material layer and the positive electrode active material layer satisfies at least one of the above conditions (1) and (2). <3> The electrode according to claim 1. <5> <1> or <2> a step of producing an electrode by the electrode production method described in a step of arranging a frame containing a resin on an edge of a current collector of the electrode to obtain an electrode sheet; a step of stacking a plurality of the electrode sheets to obtain a laminate; and heating an edge portion of the stack to weld the frame body. [Effects of the Invention]

[0006] According to one embodiment of the present disclosure, there are provided a method for manufacturing an electrode, an electrode, and a power storage device, in which cracking of an active material layer after irradiation with electromagnetic waves is suppressed. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram schematically illustrating an example of a configuration of an electrode according to an embodiment of the present disclosure. [Figure 2] 1A to 1C are diagrams illustrating an example of a method for manufacturing an electrode according to an embodiment of the present disclosure. [Figure 3] 1 is a diagram schematically illustrating an example of a configuration of a power storage device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0008] In the present disclosure, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In the numerical ranges described in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the value shown in the examples. In the present disclosure, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In the present disclosure, when there are multiple substances corresponding to each component, the amount of each component means the total amount of the multiple substances unless otherwise specified.

[0009] <Electrode manufacturing method> The method for producing an electrode film according to the present disclosure includes: forming a composition layer on a current collector, the composition layer comprising a composition including an active material, a binder, and a liquid medium; and a step of irradiating the composition layer with electromagnetic waves to obtain an active material layer containing an active material and a binder, When the active material layer is divided into two regions in the thickness direction, region X in contact with the current collector and region Y not in contact with the current collector satisfy at least one of the following conditions (1) or (2): (1) The tap density of the active material in region Y is smaller than the tap density of the active material in region X. (2) The amount of binder contained in region Y is less than the amount of binder contained in region X.

[0010] Hereinafter, the process of forming a composition layer made of a composition containing an active material, a binder, and a liquid medium on a current collector will also be referred to as a "composition layer forming process," and the process of irradiating the composition layer with electromagnetic waves to obtain an active material layer containing an active material and a binder will also be referred to as an "electromagnetic wave irradiation process."

[0011] In the present disclosure, the active material and binder contained in the composition layer are components of the active material layer obtained by irradiating the composition layer with electromagnetic waves. The liquid medium contained in the composition layer is a component that makes the composition in a state that allows it to be applied to a current collector. Therefore, the liquid medium is removed from the composition layer by irradiating it with electromagnetic waves.

[0012] According to the method of the present disclosure, even when a composition layer is irradiated with electromagnetic waves, cracking in the active material layer obtained after irradiation is effectively suppressed. The reason for this is thought to be, for example, as follows. 1, the electrode 20 produced by the method of the present disclosure has a current collector 30, a region X constituting the active material layer 40, and a region Y constituting the active material layer 40 laminated in this order. For this reason, the region Y constituting the active material layer 40 is more susceptible to the effects of electromagnetic wave irradiation than the region X, and is more likely to crack.

[0013] When region X and region Y of the active material layer satisfy condition (1) (i.e., when the tap density of the active material contained in region Y is smaller than the tap density of the active material contained in region X), region Y has relatively more voids than region X. Therefore, the pressure applied to region Y by the liquid medium vaporized by electromagnetic wave irradiation is alleviated, and cracking is suppressed. Increasing the porosity of the entire active material layer may reduce the density of the active material, resulting in a decrease in battery capacity. In the method of the present disclosure, the tap density of region X, which is less susceptible to the effects of electromagnetic wave irradiation and less susceptible to cracking, is relatively high (i.e., has a low porosity), thereby maintaining the density of the active material throughout the active material layer.

[0014] In this disclosure, the tap density (g / cm 3 ) are the mass (g) and volume (cm) of the active material after the container containing the active material is dropped from a specified height a specified number of times. 3 ) can be obtained from For example, a container with a capacity of 150 cm 3 cylinders may be used. The height from which the container is dropped may be, for example, 5 cm when the bottom surface of the container is used as the reference. The number of times the container is dropped may be, for example, 250 times.

[0015] When region X and region Y of the active material layer satisfy condition (2) (i.e., when the amount of binder contained in region Y is less than the amount of binder contained in region X), region Y has relatively more voids than region X. Therefore, the pressure applied to region Y by the liquid medium vaporized by electromagnetic wave irradiation is alleviated, and cracking is suppressed. However, reducing the amount of binder in the entire active material layer makes the active material layer brittle and prone to peeling from the current collector. In the method of the present disclosure, the amount of binder in region X, which is less susceptible to the effects of electromagnetic wave irradiation and less prone to cracking, is relatively large, thereby suppressing embrittlement of the active material layer and peeling from the current collector.

[0016] In the present disclosure, the amount of binder contained in region X or region Y of the active material layer is the content (mass %) of the binder in the total amount of solids contained in region X or region Y.

[0017] There are no particular limitations on the thickness ratio between region X and region Y that make up the active material layer. For example, the ratio (x:y) of the thickness x of region X to the thickness y of region Y may be within a range of 1:0.2 to 1:5, 1:0.3 to 1:3, or 1:0.5 to 1:2. The thickness of the active material layer formed on the current collector (total thickness of region X and region Y) is not particularly limited and can be set depending on the application of the electrode, etc. For example, the thickness of the active material layer may be in the range of 10 μm to 200 μm.

[0018] The method of the present disclosure is preferably carried out so that the pore diameter of the active material layer is 1.1 μm or more. When the pore diameter of the active material layer is 1.1 μm or more, cracking of the active material layer due to irradiation with electromagnetic waves is more effectively suppressed. The pore size of the active material layer is measured by mercury intrusion porosimetry (using a mercury intrusion porosimeter). The pore size of the active material layer can be adjusted by the particle size of the active material contained in the active material layer, the amount of binder, and the like.

[0019] In the method of the present disclosure, the pore volume of the active material layer is preferably 0.20 ml / g or more. When the pore volume of the active material layer is 0.20 ml / g or more, cracking of the active material layer due to irradiation with electromagnetic waves is more effectively suppressed. The pore volume of the active material layer is measured by mercury intrusion porosimetry (using a mercury intrusion porosimeter). The pore volume of the active material layer can be adjusted by the particle size of the active material contained in the active material layer, the amount of binder, and the like.

[0020] It is preferable that the regions X and Y of the active material layer further satisfy the following condition (3). (3) The glass transition temperature (°C) of the binder in region Y is lower than the glass transition temperature (°C) of the binder in region X.

[0021] When region X and region Y of the active material layer satisfy condition (3), a sufficient amount of binder remains in region X. As a result, the adhesion between the active material layer and the current collector via region X is sufficiently ensured, and peeling of the active material layer from the current collector is suppressed.

[0022] (Composition layer formation process) In the composition layer forming step, a composition layer made of a composition containing an active material, a binder, and a liquid medium is formed on a current collector.

[0023] Examples of a method for forming a composition layer such that the active material layer obtained by removing the liquid medium from the composition layer has a region X and a region Y include a method in which a composition x for forming region X of the active material layer is applied onto a current collector to form a composition layer x, and then a composition y for forming region Y of the active material layer is applied onto composition layer x to form a composition layer y. The method for applying the composition is not particularly limited, and can be carried out using known devices.

[0024] The type of active material contained in the composition may be a negative electrode active material used in a negative electrode, or a positive electrode active material used in a positive electrode.

[0025] Specific examples of the negative electrode active material include carbon materials such as graphite, soft carbon, and hard carbon, and silicon.

[0026] Specific examples of the positive electrode active material include lithium transition metal composite oxides (hereinafter also referred to as composite oxides). Examples of the composite oxide include composite oxides having a layered crystal structure, composite oxides having a spinel crystal structure, and composite oxides having an olivine crystal structure. Specific examples of composite oxides with a layered crystal structure include compounds represented by LiMO2 (where M is at least one transition metal selected from the group consisting of Ni, Co, and Mn), and compounds in which a different element is added to this compound. Representative examples of composite oxides with a layered crystal structure include LCO (lithium cobalt oxide), NCM (lithium nickel-cobalt-manganese oxide), and NCA (lithium nickel oxide or lithium nickel-cobalt-aluminate). A specific example of the spinel-type lithium transition metal composite oxide is LiMn2O4. A specific example of the olivine-type lithium transition metal composite oxide is LiMPO4 (M is Fe, Co, Ni, or Mn). The active material contained in the composition may be one type or a combination of two or more types.

[0027] The volume average particle diameter of the active material is not particularly limited and can be selected, for example, from the range of 5 μm to 30 μm. In the present disclosure, the volume average particle diameter of particles is the value (D50) at which the cumulative percentage from the small diameter side reaches 50% in the volume-based particle size distribution measured by a laser diffraction / scattering method.

[0028] The type of binder contained in the composition is not particularly limited, and can be selected from known materials. Specific examples of binders include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene, polypropylene, polyethylene terephthalate, cellulose, nitrocellulose, carboxymethyl cellulose, polyethylene oxide, polyepichlorohydrin, polyacrylonitrile, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), polyacrylate, and polymethacrylate. The binder contained in the composition may be one type only or a combination of two or more types.

[0029] The type of liquid medium contained in the composition is not particularly limited, and may be an organic solvent or water. Specific examples of the organic solvent include amides such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide; ureas such as N,N-dimethylethyleneurea, N,N-dimethylpropyleneurea, and tetramethylurea; lactones such as γ-butyrolactone and γ-caprolactone; carbonates such as propylene carbonate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as methyl acetate, ethyl acetate, n-butyl acetate, butyl cellosolve acetate, butyl carbitol acetate, ethyl cellosolve acetate, and ethyl carbitol acetate; glymes such as diglyme, triglyme, and tetraglyme; hydrocarbons such as toluene, xylene, and cyclohexane; sulfoxides such as dimethyl sulfoxide; sulfones such as sulfolane; and alcohols such as methanol, isopropanol, and n-butanol. The liquid medium contained in the composition may be one type alone or a combination of two or more types.

[0030] The material of the current collector on which the composition layer is formed is not particularly limited and can be selected from known materials such as aluminum, copper, nickel, titanium, stainless steel, etc. For example, when the active material layer disposed on the current collector contains a positive electrode active material, the material of the current collector may be aluminum, and when the active material layer disposed on the current collector contains a negative electrode active material, the material of the current collector may be copper.

[0031] In the composition layer forming step, the composition layer may be formed on only one surface of the current collector or on both surfaces thereof. When the composition layer is formed on both surfaces of the current collector, the composition layer may be formed on one surface of the current collector and then irradiated with electromagnetic waves, or the composition layers may be formed on both surfaces of the current collector and then irradiated with electromagnetic waves.

[0032] (Electromagnetic wave irradiation process) In the electromagnetic wave irradiation step, the composition layer obtained in the composition formation step is irradiated with electromagnetic waves to obtain an active material layer containing an active material and a binder. The means for irradiating the composition layer with electromagnetic waves is not particularly limited as long as it can evaporate the liquid medium contained in the composition layer. For example, a laser irradiation device may be used. The type of electromagnetic waves used in the electromagnetic wave irradiation step is not particularly limited as long as it can evaporate the liquid medium contained in the composition layer. For example, the electromagnetic waves may be infrared rays selected from near infrared rays (wavelength: 0.7 μm to 2.5 μm), mid infrared rays (wavelength: 2.5 μm to 4 μm), and far infrared rays (wavelength: 4 μm to 1000 μm).

[0033] From the viewpoint of the work efficiency of the electromagnetic wave irradiation step, it is preferable to carry out the electromagnetic wave irradiation while moving at least one of the object to be irradiated with electromagnetic waves or the electromagnetic wave irradiation device. For example, as shown in Fig. 2, a laminate in which a composition layer (before irradiation with electromagnetic waves) or an active material layer (after irradiation with electromagnetic waves) 40 is formed on a current collector 30 may be conveyed in the direction indicated by the arrow and passed under an electromagnetic wave irradiation device 50.

[0034] The time for irradiating the composition layer with electromagnetic waves is not particularly limited, and can be selected depending on the thickness of the composition layer, the type of liquid medium contained in the composition layer, the type or intensity of the electromagnetic waves, and the like. The time for irradiating the composition layer with electromagnetic waves may be selected, for example, from between 5 seconds and 180 seconds.

[0035] In the electromagnetic wave irradiation step, the electromagnetic wave irradiation device may be used in combination with other drying means. For example, removal of the liquid medium contained in the composition layer may be promoted by using an electromagnetic wave irradiation device in combination with a device for blowing hot air onto the active material layer (hot air oven).

[0036] The composition layer to be irradiated with electromagnetic waves in the electromagnetic wave irradiation step may be in a state where it has been subjected to a preliminary drying treatment for removing a part of the liquid medium. The composition layer to be irradiated with electromagnetic waves in the electromagnetic wave irradiation step may be in a state where it has been subjected to a press treatment in order to increase the electrode density.

[0037] <Electrode> The electrode of the present disclosure comprises: a current collector; and an active material layer containing an active material disposed on the current collector; When the active material layer is divided into two regions in the thickness direction, region X in contact with the current collector and region Y not in contact with the current collector satisfy at least one of the following conditions (1) or (2): (1) The tap density of the active material in region Y is smaller than the tap density of the active material in region X. (2) The amount of binder contained in region Y is less than the amount of binder contained in region X.

[0038] The electrode of the present disclosure has little cracking in the active material layer even when produced by a method involving irradiation with electromagnetic waves.

[0039] The electrode of the present disclosure is manufactured, for example, by the above-described method for manufacturing an electrode of the present disclosure. The details and preferred aspects of the current collector and active material layer contained in the electrode of the present disclosure are the same as the details and preferred aspects of the current collector and active material layer contained in the electrode manufactured by the above-described method for manufacturing an electrode of the present disclosure.

[0040] In the electrode of the present disclosure, the active material layer may be disposed on only one surface of the current collector, or may be disposed on both surfaces of the current collector. An electrode in which active material layers are disposed on both sides of a current collector may be a monopolar electrode in which either a negative electrode active material layer or a positive electrode active material layer is disposed on both sides of a current collector, or a bipolar electrode in which a negative electrode active material layer and a positive electrode active material layer are disposed, respectively. When active material layers are disposed on both sides of the current collector, either one of the active material layers disposed on both sides may satisfy at least one of conditions (1) or (2), or both may satisfy at least one of conditions (1) or (2).

[0041] The electrode of the present disclosure is used as an electrode for an electricity storage device such as a lithium ion secondary battery. That is, one embodiment of the present disclosure is an electricity storage device including the electrode of the present disclosure. Examples of power storage devices including the electrodes of the present disclosure include secondary batteries such as lithium ion secondary batteries, and electric double layer capacitors. Examples of applications of the power storage device including the electrode of the present disclosure include power sources for mobile vehicles such as automobiles, trains, ships, and aircraft, and power sources for various electronic devices. Among these, power sources for automobiles are preferred. The type of automobile is not particularly limited, and examples include electric vehicles (BEVs), hybrid vehicles (HEVs), plug-in hybrid vehicles (PHEVs), gasoline automobiles, and diesel automobiles.

[0042] <Method of manufacturing an electricity storage device> The method for manufacturing an electricity storage device according to the present disclosure includes: a step of manufacturing an electrode by the above-described electrode manufacturing method; a step of arranging a frame containing a resin on an edge of a current collector of the electrode to obtain an electrode sheet; a step of stacking a plurality of the electrode sheets to obtain a laminate; and heating the edge of the laminate to weld the frame.

[0043] In an energy storage device manufactured by the method of the present disclosure, all of the electrodes included in the laminate may be manufactured by the electrode manufacturing method of the present disclosure, or only some of the electrodes included in the laminate may be manufactured by the electrode manufacturing method of the present disclosure.

[0044] The electricity storage device manufactured by the method of the present disclosure has excellent sealing properties. That is, the energy storage device manufactured by the method of the present disclosure has a welded portion formed by welding a resin frame to the edge of a laminate including a plurality of electrode sheets. The welded portion functions as a sealing member that shields the inside of the energy storage device from the outside. Therefore, for example, leakage of the electrolyte sealed inside the energy storage device can be effectively prevented.

[0045] An example of the configuration of a laminate included in an electricity storage device manufactured by the method of the present disclosure is shown schematically in Fig. 3. Fig. 3 shows the configuration of a laminate used in a bipolar battery, but the electricity storage device of the present disclosure is not limited to this.

[0046] The laminate 10 shown in FIG. 3 is in a state where a plurality of electrode sheets ES are stacked in the thickness direction D1 with separators 4 sandwiched between them. Each electrode sheet ES comprises a current collector 1, an electrode E having a positive electrode active material layer 2 and / or a negative electrode active material layer 3 arranged on the current collector 1, and a resin frame 5 arranged on the edge of the current collector 1. The electrode sheets ES included in the laminate 10 include an electrode sheet having bipolar electrodes BP1 and BP2, an electrode sheet having a positive end electrode CA, and an electrode sheet having a negative end electrode AN. The bipolar electrode BP has a positive electrode active material layer 2 and a negative electrode active material layer 3 disposed on both sides of the current collector 1, the positive electrode end electrode CA has a positive electrode active material layer 2 disposed on one side of the current collector 1, and the negative electrode end electrode AN has a negative electrode active material layer 3 disposed on one side of the current collector 1. In FIG. 3, the number of bipolar electrodes BP arranged between the positive end electrode CA and the negative end electrode AN is two, but the number of bipolar electrodes BP arranged between the positive end electrode CA and the negative end electrode AN is not particularly limited.

[0047] The frame 5 disposed on the edge of the current collector 1 of the electrode sheet ES included in the laminate 10 is integrated by welding with heat. The frame body 5 is welded by heating the frame body 5 to a temperature at which the resin contained in the frame body 5 can melt. In order to reliably weld the frame body 5, heating may be performed while applying pressure to the frame body 5 in the thickness direction D1. The type of resin contained in the frame 5 is not particularly limited as long as it can be welded by heating, and can be selected from thermoplastic resins such as polyolefin, polyamide, polyester, poly(meth)acrylate, and polyimide.

[0048] The dimensions of the storage battery manufactured by the method of the present disclosure are not particularly limited and can be set depending on the application of the power storage device, etc. For example, the area of ​​the main surface (the surface with the largest area) of a storage battery is 100 cm 2 ~40,000cm 2 may be in the range of The electricity storage device manufactured by the method of the present disclosure is surrounded by a resin welded body, and therefore exhibits excellent sealing properties even when the device is large in area. [Explanation of symbols]

[0049] 20 electrodes 30 Current collector 40 Active material layer or composition layer 50 Electromagnetic wave irradiation device

Claims

1. forming a composition layer on a current collector, the composition layer comprising a composition including an active material, a binder, and a liquid medium; and a step of irradiating the composition layer with electromagnetic waves to obtain an active material layer containing an active material and a binder, a region X in contact with the current collector and a region Y not in contact with the current collector when the active material layer is divided into two regions in a thickness direction, the region X being in contact with the current collector and the region Y being not in contact with the current collector satisfy at least one of the following conditions (1) or (2): (1) The tap density of the active material contained in region Y is smaller than the tap density of the active material contained in region X. (2) The amount of binder contained in region Y is less than the amount of binder contained in region X.

2. The method for producing an electrode according to claim 1 , wherein the active material layer has a pore diameter of 1.1 μm or more or a pore volume of 0.20 ml / g or more.

3. a current collector; and an active material layer containing an active material disposed on the current collector; an electrode, wherein when the active material layer is divided into two regions in a thickness direction, a region X in contact with the current collector and a region Y not in contact with the current collector satisfy at least one of the following conditions (1) or (2): (1) The tap density of the active material contained in region Y is smaller than the tap density of the active material contained in region X. (2) The amount of binder contained in region Y is less than the amount of binder contained in region X.

4. a negative electrode active material layer including a negative electrode active material and a positive electrode active material layer including a positive electrode active material, which are disposed on respective surfaces of the current collector; The electrode according to claim 3 , wherein at least one of the negative electrode active material layer and the positive electrode active material layer satisfies at least one of the above conditions (1) and (2).

5. a step of producing an electrode by the electrode production method according to claim 1 or 2; a step of arranging a frame containing a resin on an edge of a current collector of the electrode to obtain an electrode sheet; a step of stacking a plurality of the electrode sheets to obtain a laminate; and heating an edge portion of the stack to weld the frame body.

Images