Method for manufacturing electrode layer

Abstract

Provided is a method for manufacturing an electrode layer, comprising: a step (A) in which an electrode material film is formed on a current collector foil conveyed in the direction in which a plurality of trays are connected in one direction using a conveyance member formed by connecting a plurality of trays in one direction; a step B in which the connected trays are separated from each other, and a laminate of the current collector foil and the electrode material film is divided for each tray; and a step C in which the tray on which the layered body of the divided current collector foil and the electrode material film is placed is conveyed along the connection direction of the tray, and the density and thickness of the electrode material film are measured using an X-ray inspection device.

Description

Technical Field

[0001] The invention relates to a method for manufacturing an electrode layer. Background Art

[0002] In recent years, the development of semi-solid-state batteries has been explored.

[0003] An electrode used in a semi-solid battery is produced using, for example, an electrode material including at least a powdered electrode active material and an electrolyte solution.

[0004] As a method for a manufacturing process applied to semi-solid batteries, for example, a method is disclosed in Japanese Patent Publication No. 2021-530829, which includes the following steps: continuously distributing a semi-solid electrode slurry onto a current collector; separating the semi-solid electrode slurry into separate parts; and cutting the current collector to form a finished electrode.

[0005] In addition, Japanese Patent Gazette No. 2019-212461 discloses an electrode manufacturing method, which manufactures an electrode having an active material layer on at least one surface of a collector, the electrode manufacturing method comprising: a cutting step of forming a single sheet of the electrode by cutting a sheet member; a stamping step of stamping the single sheet of the electrode using a pressing roller; and a distance measuring step of determining the intersection points of multiple edges of the single sheet of the electrode stamped and conveyed in the stamping step, and measuring the distance between the intersection points. Summary of the invention

[0006] Technical issues to be solved by the invention

[0007] As described in the above-mentioned Japanese Patent Publication No. 2021-530829 and Japanese Patent Publication No. 2019-212461, there is a method of cutting and rectangularizing the electrode layer together with the collector. As an example of this method, specifically, for example, the following method can be cited: forming an electrode material film on a collector foil placed on a conveying member formed by connecting a plurality of trays, and then separating the trays, thereby rectangularizing the electrode material film together with the collector foil.

[0008] In this method, the thickness and density of the electrode material film may be distributed depending on the film forming method and conditions. Also, depending on the conditions when the tray is separated, the thickness or density may vary at the end of the electrode material film.

[0009] Therefore, the present invention has been completed in view of the above circumstances.

[0010] An object of one embodiment of the present invention is to provide a method for producing an electrode layer having an electrode material film, the method being capable of grasping the in-plane uniformity of the density and thickness of the electrode material film.

[0011] Here, the "electrode layer" refers to a laminate of a current collector foil and an electrode material film.

[0012] Means for solving technical problems

[0013] The present invention includes the following aspects.

[0014] <1> A method for manufacturing an electrode layer, comprising:

[0015] Step A, using a conveying member formed by connecting a plurality of trays in one direction, to form an electrode material film on a collector foil conveyed along a connecting direction of the trays;

[0016] Step B, separating the connected trays and dividing the stack of collector foil and electrode material film for each tray; and

[0017] In step C, the tray on which the stacked body of the divided collector foil and the electrode material film is placed is conveyed in the connecting direction behind the tray, and the density and thickness of the electrode material film are measured using an X-ray inspection device.

[0018] <2> The method for producing an electrode layer according to <1>, wherein:

[0019] The tray is a laminate of a porous carbon layer and a carbon fiber composite material layer, and one surface of the porous carbon layer is a contact surface with the current collector foil.

[0020] <3> The method for producing an electrode layer according to <1> or <2>, wherein:

[0021] The total thickness of the pallet is 5mm to 50mm.

[0022] <4> The method for producing an electrode layer according to any one of <1> to <3>, wherein:

[0023] The information on the thickness and density of the electrode material film obtained by the X-ray inspection device is fed back to at least one of step A and step B.

[0024] <5> The method for producing an electrode layer according to <4>, wherein:

[0025] At least one of the film forming conditions of the electrode material film in step A and the separation conditions between the trays in step B is controlled based on the fed-back information.

[0026] <6> The method for producing an electrode layer according to any one of <1> to <5>, wherein

[0027] The electrode material film includes an electrode active material, a conductive auxiliary agent, and an electrolyte solution, has a thickness of 50 μm to 500 μm, and has a solid content concentration of 30 volume % to 90 volume %.

[0028] Effects of the Invention

[0029] According to one embodiment of the present invention, it is possible to provide a method for manufacturing an electrode layer having an electrode material film, the method for manufacturing an electrode layer being capable of grasping the in-plane uniformity of the density and thickness of the electrode material film. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic cross-sectional view for explaining an example of steps A to C in the method for producing an electrode layer according to the present invention.

[0031] Figure 2 This is a schematic cross-sectional view for explaining an example of a tray used in the method for producing an electrode layer according to the present invention.

[0032] Figure 3 It is a schematic cross-sectional view for explaining an example of a transport member used in the method for producing an electrode layer according to the present invention. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the purpose of the present invention. Constituent elements represented by the same symbols in the drawings refer to the same constituent elements. Regarding constituent elements and symbols repeated in the drawings, descriptions may be omitted. The ratios of dimensions in the drawings do not necessarily represent the ratios of actual dimensions.

[0034] In the present invention, the numerical range represented by "~" refers to the range including the numerical values ​​recorded before and after "~" as the lower limit and the upper limit. In the numerical range recorded in stages in the present invention, the upper limit or lower limit recorded in a certain numerical range can be replaced by the upper limit or lower limit of the numerical range recorded in other stages. Moreover, in the numerical range recorded in the present invention, the upper limit or lower limit recorded in a certain numerical range can also be replaced by the value shown in the embodiment.

[0035] In the present invention, 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 can be achieved.

[0036] In the present invention, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition refers to the total amount of the plurality of substances present in the composition unless otherwise specified.

[0037] In the present invention, a combination of two or more preferred aspects or modes becomes a more preferred aspect or mode.

[0038] In the present invention, the "solid content" refers to a component that is solid at 25°C and 1 atmosphere, and the "liquid content" refers to a component that is liquid at 25°C and 1 atmosphere.

[0039] <Method for producing electrode layer>

[0040] The manufacturing method of the electrode layer involved in the present invention includes: step A, using a conveying component composed of multiple trays connected in one direction to form an electrode material film on a collector foil conveyed along the connection direction of the trays; step B, separating the connected trays and dividing the stack of the collector foil and the electrode material film for each tray; and step C, conveying the tray carrying the divided stack of the collector foil and the electrode material film along the connection direction of the trays, and using an X-ray inspection device to measure the density and thickness of the electrode material film.

[0041] In the present invention, the electrode material film preferably comprises an electrode active material, a conductive aid and an electrolyte, has a thickness of 50 μm to 500 μm, and a solid content concentration of 30 volume % to 90 volume %. That is, the method for manufacturing an electrode layer according to the present invention preferably forms an electrode material film having a thickness of 50 μm to 500 μm and a solid content concentration of 30 volume % to 90 volume % on a collector foil.

[0042] Here, the thickness of the electrode material film is measured by the X-ray inspection device in step C. In addition, the thickness of the electrode material film is set as the arithmetic mean of the measured values ​​measured by the X-ray inspection device.

[0043] The solid content concentration of the electrode material film is calculated based on the density measured by the X-ray inspection device in step C and the composition ratio of each component contained in the electrode material film.

[0044] As described above, in the method of forming an electrode material film on a collector foil placed on a conveying member formed by connecting a plurality of trays and then separating the trays to rectangularize the electrode material film together with the collector foil, the thickness and density of the electrode material film may be distributed.

[0045] Therefore, the use of an X-ray inspection device to inspect the thickness and density of the electrode material film is being studied. However, when the electrode material film is moved from the tray during inspection using the X-ray inspection device, the electrode material film may collapse due to vibration or the like, which may cause changes in the thickness and density of the electrode material film. Therefore, a method for inspecting the formed electrode material film without changing its thickness and density is desired.

[0046] Therefore, the present inventors have found a method of applying the laminate of the current collector foil and the electrode material film to an X-ray inspection apparatus in a state where the laminate is placed on a tray, as in the method for producing an electrode layer according to the present invention.

[0047] In the method for manufacturing an electrode layer according to the present invention, as shown in the above-mentioned step C, when applied to inspection by an X-ray inspection device, collapse of the electrode material film can be suppressed, and by measuring the thickness and density of the electrode material film by the X-ray inspection device, the in-plane uniformity of the density and thickness of the electrode material film can be grasped. In addition, in the method for manufacturing an electrode layer according to the present invention, since information on the density and thickness of the electrode material film can be obtained, the information can be fed back to at least one of the steps A and B, and at least one of the film forming conditions of the electrode material film in the step A and the separation conditions between the trays in the step B can be controlled based on the fed-back information, so that an electrode material film with excellent in-plane uniformity of density and thickness can be formed.

[0048] Japanese Patent Publication No. 2021-530829 discloses a method for measuring the thickness of an electrode material film using a non-contact measurement technique, but does not describe an X-ray inspection device. In addition, Japanese Patent Publication No. 2019-212461 discloses a technique for measuring the thickness of an electrode layer by a thickness measuring unit after forming an electrode material film on a collector foil and rectangularizing it, but it is necessary to move the rectangularized electrode layer back to a conveying mechanism for conveying it to the thickness measuring unit.

[0049] Hereinafter, each step of the method for producing an electrode layer according to the present invention will be described.

[0050] refer to Figure 1 An example of step A to step C will be described.

[0051] like Figure 1 As shown, in step A, a conveying member 20 is used in which a plurality of pallets 10 are connected in one direction, and the conveying member 20 is connected in the direction of connection of the pallets 10 (in the direction of connection of the pallets 10). Figure 1 The electrode material film 42 is formed on the collector foil 30 being transported (Z direction in FIG. 1 ). Thus, a stacked body 60 of the collector foil 30 and the electrode material film 42 is formed on the tray 10 of the transport member 20.

[0052] in addition, Figure 1 The Z direction in FIG. 1 also corresponds to the conveyance direction of the collector foil 30 , the tray 10 , and the conveyance member 20 connecting them.

[0053] Next, in step B, the coupled trays 10 are separated in the Z direction, and the stacked body 60 of the collector foil 30 and the electrode material film 42 is divided for each tray 10. Thus, trays 10 on which the divided stacked body 62 of the collector foil 32 and the electrode material film 44 is placed are obtained.

[0054] Next, in step C, the tray 10 carrying the stack 62 of the divided collector foils 32 and the electrode material films 44 is transported along the tray connection direction (ie, Z direction), and the density and thickness of the electrode material films 44 are measured using an X-ray inspection device 70 .

[0055] Hereinafter, step A to step C will be described respectively.

[0056] [Process A]

[0057] In step A, a conveying member including a plurality of trays connected in one direction is used to form an electrode material film on the current collector foil conveyed along the connecting direction of the trays.

[0058] (Pallets and conveyor components)

[0059] The tray and conveying member used in step A will be described.

[0060] It is desirable that the tray has mechanical strength as a conveying member and adsorptivity for the collector foil, mechanical strength required for forming an electrode material film, and X-ray transmittance required in step C described later.

[0061] As a tray having the above-mentioned characteristics, for example, a laminate of a porous carbon layer and a carbon fiber composite material layer, one surface of which is in contact with the current collector foil, is preferable.

[0062] use Figure 2 A pallet which is a laminate of a porous carbon layer and a carbon fiber composite material layer will be described.

[0063] Figure 2 The tray 10 shown is a laminated body of a porous carbon layer 12 and a carbon fiber composite material layer 14 , and further includes a void portion 16 adjacent to the porous carbon layer 12 .

[0064] In addition, Figure 2 In the tray 10 shown, the exposed surface of the porous carbon layer 12 (that is, the surface opposite to the surface on the carbon fiber composite material layer 14 side) is the contact surface with the current collector foil.

[0065] In the following, the description is given with reference numerals omitted.

[0066] The porous carbon layer of the tray is also called porous carbon, which is a layer having continuous (connected) pores in the carbon material. Therefore, by depressurizing the pores in the porous carbon layer, the collector foil placed on the porous carbon layer can be adsorbed. Therefore, as described above, the exposed surface of the porous carbon layer becomes the contact surface with the collector foil.

[0067] Furthermore, since the porous carbon layer is made of a carbon material, it is lightweight, has high mechanical strength, and has X-ray transparency.

[0068] The pore diameter in the porous carbon layer is preferably 100 nm to 5000 nm, and more preferably 300 nm to 500 nm, from the viewpoint of the adsorptivity of the current collector foil, and from the viewpoint of mechanical strength and X-ray transmittance.

[0069] Furthermore, the porosity of the porous carbon layer is preferably 10% to 40%, and more preferably 15% to 35%, from the viewpoint of the adsorptivity of the current collector foil, and from the viewpoint of mechanical strength and X-ray transmittance.

[0070] The thickness of the porous carbon layer is preferably 3 mm to 15 mm, more preferably 5 mm to 10 mm, from the viewpoint of mechanical strength and X-ray transmittance.

[0071] The carbon fiber composite material layer of the pallet is a layer formed of a composite material (ie, carbon fiber composite material) including a base material (ie, a matrix) and carbon fibers. The carbon fiber composite material layer is provided adjacent to the porous carbon layer.

[0072] Examples of the carbon fiber composite material constituting the carbon fiber composite material layer include carbon fiber reinforced plastics (CFRP), carbon fiber reinforced carbon composite materials (C / C composite materials), and the like.

[0073] Examples of the base material include thermosetting resins (eg, epoxy resins) and resins obtained by carbonizing the resins.

[0074] From the viewpoint of mechanical strength, the thickness of the carbon fiber composite material layer is preferably 10 mm to 25 mm. In addition, the carbon fiber composite material layer can also be thinned only in the area where X-rays are transmitted. In this case, from the viewpoint of X-ray transmittance, it is preferably set to 10 mm or less, and more preferably 5 mm to 10 mm.

[0075] The gap provided in the tray is connected to a vacuum pump (not shown) or the like via a suction hole (not shown), for example, so that the gap and the pores in the porous carbon layer can be decompressed.

[0076] From the viewpoint of mechanical strength and X-ray transmittance, the total thickness of the tray is preferably 5 mm to 50 mm, more preferably 20 mm to 50 mm, and even more preferably 25 mm to 35 mm.

[0077] The total thickness of the tray referred to herein refers to the distance from the contact surface with the collector foil (ie, the suction surface of the collector foil) to the opposite surface (ie, the back surface).

[0078] The total thickness of the pallet is measured using, for example, a vernier caliper.

[0079] In process A, a conveying member is used in which a plurality of pallets are connected in one direction. Figure 3 The connection of the tray will be described.

[0080] like Figure 3 As shown, a plurality of pallets 10 are connected using a carrier 80, a guide rail 82 disposed on the carrier 80, and a fixing component 84 for fixing the pallets 10. The pallet 10 has a guide groove (not shown) on its back. The plurality of pallets 10 are placed on the carrier 80 by fitting the guide groove on the back side onto the guide rail 82. Then, each pallet 10 is slid in the direction of the arrow along the guide rail 82, so that the pallets 10 are pressed and fitted together. Then, the fitted pallets 10 are fixed to each other using the fixing component 84, and a conveying component formed by connecting the plurality of pallets 10 in one direction is obtained.

[0081] (Formation of electrode material film)

[0082] Next, a method for forming an electrode material film on the current collector foil conveyed by the conveying member in step A will be described.

[0083] The method for forming the electrode material film on the collector foil is not limited as long as the electrode material film can be formed as a continuous layer with a desired thickness on the collector foil.

[0084] As a method for forming an electrode material film on a collector foil, for example, the following method is preferred: Figure 1 As shown, the electrode material 40 is applied to the current collector foil being transported in the Z direction, and the thickness of the electrode material 40 is limited by the molding member 50 to form an electrode material film 42 .

[0085] The following, Figure 1 The method for forming the electrode material film 42 shown will be described in more detail.

[0086] like Figure 1As shown, the molding member 50 is arranged to maintain a certain distance from the surface of the conveying member 20 or the surface of the collector foil 30 placed on the conveying member 20. The molding member 50 preferably maintains a certain distance even when it is in contact with the electrode material 40 and the collector foil 30 is conveyed and moved in the Z direction. That is, the molding member 50 applies pressure to resist the repulsive force (i.e., the force that pushes the molding member 50 away) from the contacted electrode material 40 in order to maintain a certain distance from the surface of the conveying member 20 or the surface of the collector foil 30 placed on the conveying member 20.

[0087] like Figure 1 As shown, a reservoir 46 is formed between the collector foil 30 and the forming member 50 by the electrode material 40 supplied to the collector foil 30 by the supply mechanism 48. In this state, the collector foil 30 is transported and moved in the Z direction by the conveying member 20, and the electrode material 40 passes through the gap between the forming member 50 and the surface of the conveying member 20 or the surface of the collector foil 30 placed on the conveying member 20. When the electrode material 40 passes through the gap, the thickness of the electrode material 40 is restricted by contact with the forming member 50, and then the electrode material 40 is applied to the surface of the collector foil 30, so that an electrode material film 42 is formed on the collector foil 30 by the electrode material 40.

[0088] In addition, the contact portion of the molded component 50 with the electrode material 40 is preferably vibrated. Since the contact portion of the molded component 50 with the electrode material 40 vibrates, the vibration is transmitted to the electrode material 40 and a shear force is applied, which may cause a decrease in viscosity and an increase in fluidity of the electrode material 40. As a result, as described above, at least the surface of the electrode material film 42 formed by applying on the collector foil 30 becomes flat, and it is easy to form an electrode material film 42 with less thickness deviation.

[0089] In the method for forming the electrode material film 42 , as described above, it is preferable to control the amount of electrode material 40 supplied onto the collector foil 30 and the amount of electrode material film 42 formed so as to form a reservoir 46 of the electrode material 40 between the collector foil 30 and the molding member 50 .

[0090] As a means for imparting electrode material to the collector foil (for example, Figure 1 The feeding mechanism 48 in the figure may be a mechanism for intermittently or continuously feeding the electrode material onto the collector foil (eg, a hopper, a screw feeder, a disc feeder, a vibrating feeder, etc.).

[0091] Furthermore, when applying the electrode material to the current collector foil, a limiting frame may be used from the viewpoint of uniformly applying the electrode material.

[0092] In addition, the conveying movement mechanism of the conveying member is not particularly limited. Figure 3As shown, the transport member formed by connecting a plurality of trays 10 is transported in a state of being placed on the stage 80 by moving the stage 80 using an LM guide (Linear Motion Guide) 90 or the like.

[0093] [Process B]

[0094] In step B, the connected trays are separated and the stacked body of the current collector foil and the electrode material film is divided for each tray.

[0095] In step B, the long strip of electrode material film formed in step A is cut together with the collector foil into the length of the tray (specifically, the length in the conveying direction of the tray (in the Figure 1 Length in Z direction).

[0096] In step B, the connected trays are separated from each other. The separation conditions may be appropriately determined according to the collapsibility of the electrode material film to be formed.

[0097] As the separation condition, for example, there can be mentioned the speed and acceleration when the trays are separated from each other.

[0098] It is preferred that the speed or acceleration for separating the trays be reduced as the electrode material film collapses more easily.

[0099] refer to Figure 3 An example of separating the trays will be described.

[0100] For example, Figure 3 As shown, after forming a stack of collector foil and electrode material film on a conveying member formed by connecting and fixing a plurality of trays 10 on a stage 80, first, the fixing by the fixing member 84 is released. Then, the trays 10 are slid one by one along the guide rails 82, and the trays 10 are separated from each other.

[0101] The separated trays are detached from the stage 80 one by one, and are moved so as to pass through the X-ray inspection device in the step C described later.

[0102] [Process C]

[0103] In step C, the tray on which the stacked body of the divided collector foil and the electrode material film is placed is conveyed along the connection direction of the trays, and the density and thickness of the electrode material film are measured using an X-ray inspection device.

[0104] In step C, the stacked body of the collector foil and the electrode material film is conveyed in a state where each tray divided in step B carries the stacked body, and in this state, the density and thickness of the electrode material film are measured using an X-ray inspection device on the conveying path. That is, in step C, an X-ray inspection is performed online by passing the tray carrying the stacked body of the collector foil and the electrode material film through the X-ray inspection device provided on the conveying path.

[0105] (X-ray inspection equipment)

[0106] The X-ray inspection device includes an X-ray source and a detection unit, and can determine the density and thickness of the electrode material film by irradiating the stacked body placed on the tray with X-rays and detecting the X-rays that have passed through the stacked body and the tray.

[0107] Specific examples of the X-ray inspection apparatus include an X-ray inspection apparatus equipped with a photon sensor in a coating amount measurement system manufactured by NORDSON ADVANCED TECHNOLOGY KK, and an X-ray inspection apparatus described in JP-A-2022-519242.

[0108] A region where a large dose of X-rays is detected indicates that the electrode material film has a low density or a small thickness, and a region where a small dose of X-rays is detected indicates that the electrode material film has a high density or a large thickness.

[0109] That is, it can be judged that the smaller the difference (variation) in the X-ray dose in the film surface direction of the electrode material film is, the better the in-plane uniformity of the density and thickness of the electrode material film is.

[0110] In addition, the X-ray transmission capability may be different depending on the type of collector foil and tray. Therefore, in the X-ray inspection device, it is preferred to change at least one of the X-ray irradiation intensity and the X-ray detection sensitivity in the light emitting unit according to the type of collector foil and tray. By doing so, the density and thickness of the electrode material film can be measured with good accuracy.

[0111] (feedback)

[0112] The information on the thickness and density of the electrode material film obtained by the X-ray inspection device is preferably fed back to at least one of step A and step B. By controlling one or more of the conditions in step A and the conditions in step B based on the fed-back information, the in-plane uniformity of the density and thickness of the electrode material film formed under the controlled conditions can be improved.

[0113] Specifically, it is preferred to control at least one of the film forming conditions of the electrode material film in step A and the separation conditions between the trays in step B based on the fed-back information. By doing so, more electrode layers with excellent in-plane uniformity of the density and thickness of the electrode material film can be obtained on a production line to which the method for manufacturing an electrode layer according to the present invention is applied.

[0114] The film forming conditions of the electrode material film in process A which are controlled based on the feedback information include the amount of electrode material applied to the collector foil, the distribution of electrode material applied to the collector foil, the conveying speed of the collector foil, the distance between the surface of the forming component and the conveying component (the width of the gap), etc.

[0115] Furthermore, as the separation conditions of the trays in step B that are controlled based on the fed-back information, there can be cited the speed and acceleration when the trays are separated.

[0116] Specifically, when it is determined using information on the thickness and density of the electrode material film obtained by an X-ray inspection device that the density of the electrode material film in a certain area on the tray is low (or high) or the thickness is small (or large), it is preferably controlled by performing a two-stage process of adjusting the distribution of the electrode material on the collector foil and adjusting the distance between the surface of the forming component and the surface of the conveying component in the width direction.

[0117] Furthermore, when it is determined from the information on the thickness and density of the electrode material film obtained by the X-ray inspection device that the density of the electrode material film in an area at a certain end of the tray is low or the thickness is small, it is preferred to control it by performing a two-stage processing of increasing the amount of electrode material supplied to the area corresponding to the end of the electrode material film (the area on the collector foil) and supplying the electrode material again only to the end of the electrode material film.

[0118] Here, the above two-stage processing will be described.

[0119] The two-stage process refers to a process of applying the electrode material to the electrode material film as needed after the electrode material film is formed on the collector foil. The two-stage process is performed before the trays are separated, that is, before step B. In this case, a mechanism for applying the electrode material to the collector foil twice can be used to apply the electrode material to the electrode material film (for example, Figure 1 The electrode material imparting mechanism 48 in the embodiment may be another electrode material imparting mechanism different from the electrode material imparting mechanism on the collector foil. In the latter case, the electrode material imparting mechanism on the electrode material film can be arranged in series on the downstream side of the conveying direction closer to the conveying member than the electrode material imparting mechanism on the collector foil.

[0120] In the latter case, in a two-stage process, e.g. Figure 1 As shown, the following method can be cited: after the electrode material film 42 is formed by limiting the thickness of the electrode material 40 applied to the collector foil 30 using the forming member 50, the electrode material is applied to the electrode material film 42 using an electrode material applying mechanism (not shown) before performing step B. In this case, after the electrode material is applied to the electrode material film, the thickness of the electrode material can be limited by another forming member.

[0121] And, in the former case, in a two-stage process, e.g. Figure 1 As shown, the following method can be cited: after the electrode material film 42 is formed by limiting the thickness of the electrode material 40 applied to the collector foil 30 by the forming member 50, the collector foil 30 having the electrode material film 42 is transported and moved in the direction opposite to the Z direction before the step B is performed, and the electrode material is applied to the electrode material film 42 by the applying mechanism 48 again. In this case, after the electrode material is applied to the electrode material film, the thickness of the electrode material is limited again by the forming member 50.

[0122] The feedback can be performed manually or automatically based on the information of the thickness and density of the electrode material film obtained by the X-ray inspection device. In the latter case, it can be determined whether the density of the electrode material film in a certain area on the tray is low or the thickness is small based on the information of the thickness and density of the electrode material film obtained by the X-ray inspection device. Then, if it is determined that the density of the electrode material film in a certain area on the tray is low or the thickness is small, any of the above controls is performed.

[0123] Any of the above controls is preferably performed when the thickness or density of the electrode material film obtained by the X-ray inspection device exceeds ±5% relative to the set thickness (target thickness) or density. Furthermore, the thickness or density of the electrode material film after performing any of the above controls is preferably adjusted to be less than ±3% relative to the set thickness or density, and more preferably adjusted to be less than ±1%.

[0124] In the above-described manner, the electrode material film is formed on the current collector foil placed on the tray.

[0125] 〔Other processes〕

[0126] The method for producing an electrode layer according to the present invention may include other steps.

[0127] As another step, for example, there is a step of pressurizing the electrode material film.

[0128] (Step of Pressurizing Electrode Material Film)

[0129] The method for producing an electrode layer according to the present invention may include a step of pressurizing the electrode material film.

[0130] Since the method for producing an electrode layer according to the present invention includes a pressurizing step, the density of the electrode material can be increased and the density and thickness of the solid content can be made uniform within a plane.

[0131] In this step, for example, the electrode material film is preferably pressed by pressing the stack placed on the tray using a press roller. At this time, a thin film is preferably placed on the electrode material film, and the stack is pressed by pressing the press roller from the thin film.

[0132] In this step, for example, a press machine can be used as the pressurizing mechanism. Furthermore, a vibrating pressurizing mechanism can also be used as the pressurizing mechanism.

[0133] When the laminate is pressurized, the pressure is preferably 0.01 MPa to 100 MPa, more preferably 0.1 MPa to 50 MPa, and particularly preferably 0.2 MPa to 10 MPa.

[0134] In this step, a plurality of pressurizing mechanisms may be used to pressurize the stacked body in stages. By using a plurality of pressurizing mechanisms to pressurize the electrode material film in stages, the density and thickness of the electrode material can be made more uniform.

[0135] In this step, it is preferable to perform the step by relatively moving the pressurizing mechanism and the electrode material film (specifically, the collector foil on which the electrode material film is formed).

[0136] In the present invention, "moving the pressurizing mechanism and the electrode material film relative to each other" includes moving the pressurizing mechanism in one direction relative to the electrode material film, moving the electrode material film in one direction relative to the pressurizing mechanism, and moving the pressurizing mechanism and the electrode material film in one direction respectively, but it is preferred to move the electrode material film in one direction relative to the pressurizing mechanism.

[0137] In this step, from the viewpoint of improving moldability, the electrode material film heated at, for example, 30° C. to 100° C. may be pressed.

[0138] Hereinafter, the details of the collector foil and the molded component used in the method for producing the electrode layer according to the present invention will be described.

[0139] Furthermore, the details of the electrode materials (including materials such as an electrode active material, a conductive auxiliary agent, and an electrolyte solution) are also described.

[0140] [Current Collector Foil]

[0141] The current collector foil is not particularly limited, and a known current collector foil (positive electrode current collector foil and negative electrode current collector foil) can be used.

[0142] Examples of the positive electrode current collector foil include foils (i.e., metal layers) of aluminum, aluminum alloys, stainless steel, nickel, and titanium. The positive electrode current collector foil is preferably aluminum or an aluminum alloy. The positive electrode current collector foil may also be aluminum having a coating layer containing one or more of carbon, nickel, titanium, silver, gold, platinum, and vanadium oxide on the surface.

[0143] As the negative electrode current collector foil, for example, foil (i.e., metal layer) of aluminum, copper, copper alloy, stainless steel, nickel and titanium can be cited. The negative electrode current collector foil is preferably aluminum, copper, copper alloy or stainless steel, more preferably copper or copper alloy. The negative electrode current collector foil can also be copper or stainless steel having a coating layer containing one or more of carbon, nickel, titanium, silver and lithium on the surface.

[0144] As the current collector foil, aluminum foil (including aluminum foil having the above-mentioned coating layer on the surface) and copper foil (including copper foil having the above-mentioned coating layer on the surface) are preferred. Aluminum foil is generally used as the current collector foil in the positive electrode. Copper foil is generally used as the current collector foil in the negative electrode.

[0145] In addition, the collector foil may be a laminate of the metal layer and the resin film exemplified as the positive electrode collector foil or the negative electrode collector foil. The resin film used in the laminate may include a polyethylene terephthalate (PET) film, a polypropylene (PP) film, a polyethylene (PE) film, a cyclic olefin polymer (COP, COC) film, a triacetyl cellulose (TAC) film, a polyimide (PI) film, a polyamide (PA) film, and the like.

[0146] When the laminate of the metal layer and the resin film is used, it is preferred that the surface of the metal layer forming the electrode material film can be divided in the plane direction.

[0147] For example, a collector foil is used in which a plurality of metal layers (metal layers to be collector foils) of a desired size are separated from each other on a resin film, and the resin film portion between the metal layers is bent toward the side opposite to the metal layer side so that the separated metal layers are in contact with each other without a gap. In such a collector foil, the metal layers in contact with each other without a gap can be divided along with the separation of the trays.

[0148] From the viewpoint of transportability and the like, the thickness of the collector foil (including the case of a laminate) is preferably 3 μm or more, more preferably 5 μm or more, and particularly preferably 10 μm or more.

[0149] From the viewpoint of flexibility and lightness, the thickness of the current collector foil is preferably 100 μm or less, more preferably 70 μm or less, and particularly preferably 50 μm or less.

[0150] The thickness of the collector foil is the arithmetic mean of thicknesses at three locations measured by cross-sectional observation. A known microscope (for example, a scanning electron microscope) can be used for cross-sectional observation.

[0151] [Molding parts]

[0152] Preferred examples of the molding member include a blade and a roller.

[0153] As described above, by using a molding member that can vibrate or oscillate when in contact with the electrode material, the scraper and the roller as the molding member can vibrate the electrode material.

[0154] (Scraper)

[0155] The scraper is a plate-like component. The shape, size, material, etc. of the contact portion with the electrode material can be appropriately determined based on the various physical properties of the electrode material (type of electrode active substance, solid content concentration, composition of the electrolyte (viscosity, surface tension), etc.), the size and thickness of the electrode material film formed, etc.

[0156] Furthermore, it is preferred that the portion of the scraper that contacts the electrode material does not easily adhere to the electrode material. For example, it is preferred that at least the surface of the scraper exhibits releasability.

[0157] For example, the scraper may be made of a fluorine-based resin such as polytetrafluoroethylene (PTFE), a resin such as polyetheretherketone (PEEK), or a metal such as stainless steel, aluminum, iron, or cemented carbide, or may be made of ceramics.

[0158] Furthermore, in order to impart mold release properties to the surface, the blade may include a surface layer exhibiting mold release properties (for example, a surface layer containing a fluorine-based resin, a surface layer containing silicon-based particles and a resin).

[0159] Furthermore, from the viewpoint of improving wear resistance, the scraper may have a high-hardness coating of titanium oxide, titanium nitride (TiN), tungsten carbide, or the like on the scraper body made of metal or ceramic.

[0160] (Roller)

[0161] The roller is a component whose outer peripheral surface can rotate. Its size, material, etc. can be appropriately determined according to the physical properties of the electrode material (type of electrode active material, solid content concentration, composition of electrolyte (viscosity, surface tension), etc.), the size and thickness of the electrode material film formed, etc.

[0162] The material constituting the outer peripheral surface of the roller may be the same as that of the blade, and may have a surface layer exhibiting mold release properties.

[0163] The outer diameter of the roller is not particularly limited, and may be, for example, 20 mm to 30 mm.

[0164] Furthermore, since the roller rotates, the friction coefficient between its outer peripheral surface and the electrode material can be considered to be 0. However, as a result, the adhesion with the electrode material may be improved, so it is preferable to interpose a film between the electrode material and the outer peripheral surface of the roller.

[0165] [Electrode materials]

[0166] The electrode material includes an electrode active material, a conductive auxiliary agent, and an electrolyte solution, and may include additives as necessary.

[0167] (Electrode Active Material)

[0168] The electrode active material is a material that can absorb and release ions of a metal element belonging to Group 1 or Group 2 of the periodic table. The electrode active material is included in the solid component.

[0169] Examples of the electrode active material include a positive electrode active material and a negative electrode active material.

[0170] -Positive electrode active material-

[0171] The positive electrode active material is not limited, and a known electrode active material used in a positive electrode can be used. The positive electrode active material is preferably a positive electrode active material that can reversibly absorb and release lithium ions.

[0172] Specific examples of the positive electrode active material include transition metal oxides and elements that can form a complex with lithium (for example, sulfur). Among the above, the positive electrode active material is preferably a transition metal oxide.

[0173] The transition metal oxide is preferably a transition metal oxide containing at least one transition metal element (hereinafter referred to as “element Ma”) selected from the group consisting of Co (cobalt), Ni (nickel), Fe (iron), Mn (manganese), Cu (copper) and V (vanadium).

[0174] When the transition metal oxide contains Li and the element Ma, the molar ratio of Li to Ma (Li / Ma) is preferably 0.3 to 2.2.

[0175] Furthermore, the transition metal oxide may contain at least one transition metal element (hereinafter referred to as "element Mb") selected from the group consisting of Group 1 elements other than lithium, Group 2 elements, Al (aluminum), Ga (gallium), In (indium), Ge (germanium), Sn (tin), Pb (lead), Sb (antimony), Bi (bismuth), Si (silicon), P (phosphorus) and B (boron). The content of element Mb is preferably 0 mol% to 30 mol% relative to the amount of substance of element Ma.

[0176] Examples of the transition metal oxide include transition metal oxides having a layered rock salt structure, transition metal oxides having a spinel structure, lithium-containing transition metal phosphate compounds, lithium-containing transition metal halophosphate compounds, and lithium-containing transition metal silicate compounds.

[0177] Examples of transition metal oxides having a layered rock salt structure include LiCoO 2 (lithium cobalt oxide [LCO]), LiNi 2 O 2 (Lithium Nickel Oxide), LiNi 0.85 Co 0.10 Al 0.05 O 2 (lithium nickel cobalt aluminum oxide [NCA]), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (NMC) and LiNi 0.5 Mn 0.5 O 2 (lithium manganese nickel oxide).

[0178] Examples of transition metal oxides having a spinel structure include LiCoMnO 4 , Li 2 FeMn 3 O 8 , Li 2 CuMn 3 O 8 , Li 2 CrMn 3 O 8 Li 2 NiMn 3 O 8 .

[0179] Examples of lithium-containing transition metal phosphate compounds include olivine-type iron phosphates (e.g., LiFePO 4 Li 3 Fe 2 (PO 4 ) 3 ), ferric pyrophosphate (e.g., LiFeP 2 O 7 ), cobalt phosphates (e.g., LiCoPO 4 ), monoclinic NASICON-type vanadium phosphate salts (e.g., Li 3 V 2 (PO 4 ) 3 (lithium vanadium phosphate)).

[0180] Examples of lithium-containing transition metal halophosphate compounds include fluoroferric phosphates (e.g., Li 2 FePO 4 F), manganese fluorophosphate salts (e.g., Li 2 MnPO 4 F) and cobalt fluorophosphate salts (e.g., Li 2 CoPO 4 F).

[0181] Examples of lithium-containing transition metal silicate compounds include Li 2 FeSiO 4 , Li 2 MnSiO 4 Li 2 CoSiO 4 .

[0182] The transition metal oxide is preferably a transition metal oxide having a layered rock salt structure, more preferably selected from the group consisting of LiCoO 2 (lithium cobalt oxide [LCO]), LiNi 0.85 Co 0.10 Al 0.05 O 2 (nickel cobalt aluminum oxide [NCA]) and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 At least one compound of the group consisting of (lithium nickel manganese cobalt oxide [NMC]).

[0183] The positive electrode active material may be a commercially available product or a synthetic product produced by a known method (eg, calcination method). For example, the positive electrode active material obtained by calcination method may be washed with water, an acidic aqueous solution, an alkaline aqueous solution or an organic solvent.

[0184] Furthermore, the positive electrode active material may have a carbon coating on its surface.

[0185] The shape of the positive electrode active material is not limited, but is preferably in the form of particles from the viewpoint of handleability.

[0186] The volume average particle size of the positive electrode active material is not limited, and can be, for example, 0.1 μm to 50 μm. The volume average particle size of the positive electrode active material is preferably 0.3 μm to 40 μm, and more preferably 0.5 μm to 30 μm.

[0187] The positive electrode active material has a volume average particle size of 0.3 μm or more, which can suppress the splashing of the positive electrode active material during operation. The positive electrode active material has a volume average particle size of 40 μm or less, which can easily adjust the thickness of the electrode layer and suppress the generation of voids during the molding process.

[0188] The volume average particle size of the positive electrode active material is measured by the following method.

[0189] A dispersion containing less than 0.1% by mass of a positive electrode active material is prepared by mixing the positive electrode active material with a solvent (e.g., pure water, ethanol, heptane, octane, toluene or xylene). The dispersion irradiated with 1kHz ultrasonic waves for 10 minutes is used as a measurement sample. Using a laser diffraction / scattering particle size distribution measuring device (e.g., LA-960 manufactured by HORIBA, Ltd.), 50 data readings are performed at a temperature of 25°C, and the volume average particle size is calculated based on the volume frequency particle size distribution. A quartz colorimetric cell is used for the measurement. The above measurement is performed using 5 samples, and the average of the measured values ​​is taken as the volume average particle size of the positive electrode active material. For other detailed conditions, refer to "JIS Z 8828:2013" as needed.

[0190] As a method for adjusting the particle size of the positive electrode active material, for example, a method using a pulverizer, a disintegrator, or a classifier can be cited. Also, as a method for adjusting the particle size of the positive electrode active material, a known milling method can be applied.

[0191] The positive electrode active material may be used alone or in combination of two or more.

[0192] Furthermore, even when a single type of positive electrode active material is used, positive electrode active materials having different particle sizes may be used in combination.

[0193] The content of the positive electrode active material relative to the total volume of the electrode material is preferably 30% by volume to 60% by volume, more preferably 35% by volume to 55% by volume, and even more preferably 40% by volume to 50% by volume.

[0194] In the method for producing an electrode layer according to the present invention, the amount of the positive electrode active material used is determined so that the content in the electrode material film is within the above range.

[0195] -Negative electrode active material-

[0196] The negative electrode active material is not limited, and a known electrode active material used in a negative electrode can be used. The negative electrode active material is preferably a negative electrode active material that can reversibly absorb and release lithium ions.

[0197] As the negative electrode active material, for example, carbonaceous materials, metal oxides (for example, tin oxide), silicon oxide, metal composite oxides, lithium monomers, lithium alloys (for example, lithium aluminum alloys) and metals that can form alloys with lithium (for example, Sn, Si and In) can be cited. Among the above, from the viewpoint of reliability, the negative electrode active material is preferably a carbonaceous material or a lithium composite oxide.

[0198] The carbonaceous material is a material substantially composed of carbon.

[0199] Examples of carbonaceous materials include petroleum pitch, carbon black (e.g., acetylene black), graphite (e.g., natural graphite and artificial graphite (e.g., vapor-grown graphite)), hard carbon, and carbonaceous materials obtained by calcining synthetic resins (e.g., polyacrylonitrile (PAN) and furfuryl alcohol resin). Examples of carbonaceous materials include carbon fibers (e.g., polyacrylonitrile-based carbon fibers, cellulose-based carbon fibers, pitch-based carbon fibers, vapor-grown carbon fibers, dehydrated PVA (polyvinyl alcohol)-based carbon fibers, lignin carbon fibers, glassy carbon fibers, and activated carbon fibers). Examples of graphite include mesophase microspheres, graphite whiskers, and flat graphite.

[0200] In the present invention, "flat plate shape" means a shape having two main planes facing in opposite directions.

[0201] As the metal composite oxide, a metal composite oxide capable of occluding and releasing lithium is preferred.

[0202] From the viewpoint of high current density charge and discharge characteristics, the metal composite oxide capable of occluding and releasing lithium preferably contains at least one element selected from the group consisting of titanium and lithium.

[0203] The metal oxide and the metal composite oxide are particularly preferably amorphous oxides.

[0204] The metal oxide and the metal composite oxide are also preferably chalcogenides. Chalcogenides are reaction products of metal elements and elements of Group 16 in the periodic table.

[0205] Among the compound group including amorphous oxides and chalcogenides, amorphous oxides and chalcogenides of semimetallic elements are preferred, and oxides and chalcogenides containing at least one element selected from the group including elements of Groups 13 to 15 of the periodic table, Al, Ga, Si, Sn, Ge, Pb, Sb and Bi are more preferred.

[0206] It is also preferred that the negative electrode active material further comprises titanium. From the viewpoint that the volume change during the storage and release of lithium ions is small and the rapid charge and discharge characteristics are excellent, and the life of the lithium ion secondary battery can be improved by suppressing the degradation of the electrode, the negative electrode active material comprising titanium is preferably Li4 Ti 5 O 12 (lithium titanate [LTO]).

[0207] The negative electrode active material may be a commercial product or a synthetic product produced by a known method (eg, calcination method). For example, the negative electrode active material obtained by calcination method may be washed with water, an acidic aqueous solution, an alkaline aqueous solution or an organic solvent.

[0208] The negative electrode active material can be obtained as, for example, CGB20 (Nippon Graphite Industries Co., Ltd.).

[0209] The composition of the negative electrode active material was measured using inductively coupled plasma (ICP) emission spectrometry.

[0210] The shape of the negative electrode active material is not limited, but is preferably in the form of particles from the viewpoint of easy handling and easy control of uniformity during mass production.

[0211] The volume average particle size of the negative electrode active material is preferably 0.1 μm to 60 μm, more preferably 0.3 μm to 50 μm, and particularly preferably 0.5 μm to 40 μm.

[0212] The volume average particle size of the negative electrode active material is measured by a method corresponding to the method for measuring the volume average particle size of the positive electrode active material described above.

[0213] Examples of methods for adjusting the particle size of the negative electrode active material include a method using a pulverizer or a classifier.

[0214] The negative electrode active material may be used alone or in combination of two or more.

[0215] Furthermore, even when a single type of negative electrode active material is used, negative electrode active materials having different particle sizes may be used in combination.

[0216] The content of the negative electrode active material relative to the total volume of the electrode material is preferably 30% by volume to 60% by volume, more preferably 35% by volume to 57% by volume, and even more preferably 45% by volume to 55% by volume.

[0217] In the method for producing an electrode layer according to the present invention, the amount of the negative electrode active material used is determined so that the content in the electrode material film is within the above range.

[0218] The surfaces of the positive electrode active material and the negative electrode active material may be coated with a surface coating agent, respectively. As the surface coating agent, for example, a metal oxide containing Ti, Nb, Ta, W, Zr, Si or Li may be cited. As the above-mentioned metal oxide, for example, titanate spinel, tantalum oxide, niobium oxide and lithium niobate compound may be cited.

[0219] (Conductive additive)

[0220] The electrode material film contains a conductive auxiliary agent from the viewpoint of improving the electron conductivity of the electrode active material. The conductive auxiliary agent is not limited, and a known conductive auxiliary agent can be used.

[0221] The conductive auxiliary agent is included in the solid component.

[0222] As conductive aids, for example, graphite (for example, natural graphite and artificial graphite), carbon black (for example, acetylene black, Ketjen black and furnace black), amorphous carbon (for example, needle coke), carbon fiber (for example, vapor-grown carbon fiber and carbon nanotube), other carbonaceous materials (for example, graphene and fullerene), metal powder (for example, copper powder and nickel powder), metal fiber (for example, copper fiber and nickel fiber) and conductive polymers (for example, polyaniline, polypyrrole, polythiophene, polyacetylene and polyphenylene derivatives) can be cited.

[0223] The conductive auxiliary agent may be used alone or in combination of two or more.

[0224] The content of the conductive aid relative to the total volume of the electrode material is preferably 0.05 to 5% by volume, more preferably 0.1 to 4% by volume, and even more preferably 0.5 to 3% by volume.

[0225] In the method for producing an electrode layer according to the present invention, the amount of the conductive additive used is determined so that the content in the electrode material film is within the above range.

[0226] (Electrolyte)

[0227] The electrolyte is not particularly limited, and a known electrolyte can be used. For example, an electrolyte containing an electrolyte and a solvent can be cited. As a specific electrolyte, for example, an electrolyte containing a lithium salt compound as an electrolyte and a carbonate compound as a solvent can be cited.

[0228] As the lithium salt compound, for example, lithium hexafluorophosphate can be mentioned. The electrolyte solution may contain a single lithium salt compound, or may contain two or more lithium salt compounds.

[0229] As carbonate compounds, for example, chain carbonate compounds such as ethyl methyl carbonate (also referred to as EMC), dimethyl carbonate (also referred to as DMC), diethyl carbonate (DEC), cyclic carbonate compounds such as ethylene carbonate (also referred to as EC), and propylene carbonate (also referred to as PC) can be cited. The electrolyte may contain a single carbonate compound, may contain two or more carbonate compounds, and may also use one or more chain carbonate compounds and one or more cyclic carbonate compounds in combination.

[0230] As the electrolyte contained in the electrolytic solution, for example, a well-known inorganic solid electrolyte can be used.

[0231] As a component of the electrolytic solution, for example, an ionic liquid can be used. The ionic liquid can be used as an electrolyte or as a solvent.

[0232] The content of the electrolyte relative to the total volume of the electrode material is preferably 70% by volume or less, and may be 50% by volume or less, and may be 40% by volume or less. The lower limit of the content of the electrolyte relative to the total volume of the electrode material is not limited, and may be 10% by volume or more, and may be 30% by volume or more.

[0233] The content of the electrolyte solution relative to the total volume of the electrode material is preferably, for example, 30% by volume to 50% by volume.

[0234] (Solvent)

[0235] The electrode material film may contain, as a liquid component, a solvent other than the solvent contained as a component of the electrolytic solution (hereinafter, also simply referred to as a “solvent”).

[0236] Examples of the solvent include alcohol compound solvents, ether compound solvents, amide compound solvents, amino compound solvents, ketone compound solvents, aromatic compound solvents, aliphatic compound solvents, and nitrile compound solvents.

[0237] The boiling point of the solvent is preferably 50° C. or higher, more preferably 70° C. or higher at normal pressure (ie, one atmosphere). The upper limit of the boiling point of the solvent is preferably 250° C. or lower, more preferably 220° C. or lower at normal pressure (ie, one atmosphere).

[0238] The solvent may be used alone or in combination of two or more.

[0239] The content of the liquid component (i.e., electrolyte and solvent) relative to the total volume of the electrode material is preferably 70% by volume or less, and may be 50% by volume or less, and may be 40% by volume or less. The lower limit of the content of the liquid component relative to the total volume of the electrode material is not limited, and may be 10% by volume or more, and may be 30% by volume or more.

[0240] The content of the liquid component relative to the total volume of the electrode material is preferably 30% by volume to 50% by volume.

[0241] In addition, the liquid component contained in the electrode material film, that is, the component in the electrode material film that is liquid at 25° C. is preferably liquid even at -10° C., and preferably liquid even at -20° C. That is, the component in the electrode material film that is liquid at 25° C. is preferably a component that does not solidify at -10° C., and preferably a component that does not solidify even at -20° C.

[0242] (Other ingredients)

[0243] The electrode material film may contain a binder, a dispersant, other additives, etc. in addition to the above components. However, from the viewpoint of improving energy density, the electrode material film preferably has a low binder content, and more preferably contains no binder.

[0244] Examples of the binder include fluorine-containing resins, hydrocarbon-based thermoplastic resins, acrylic resins, and urethane resins.

[0245] Furthermore, the dispersant may be any known dispersant as long as it can disperse the dispersion object.

[0246] Furthermore, as other additives, known additives added to electrodes can be used.

[0247] <<Electrode layer>>

[0248] The electrode layer obtained by the method for producing an electrode layer according to the present invention can be used as various electrodes. In addition, the sheet-like electrode layer can be used as an electrode as it is, or the electrode layer can be used as an electrode after further processing.

[0249] The sheet-shaped electrode layer is preferably an electrode layer of a semi-solid secondary battery.

[0250] From the viewpoint of improving battery performance (eg, discharge capacity and output characteristics), the electrode layer preferably has a thickness of 50 μm to 500 μm and a solid content of 30 vol % to 90 vol %, similarly to the electrode material film.

[0251] The thickness of the electrode layer can be measured by the same method as the thickness of the electrode material film, or can be measured by the same method as the thickness of the collector foil.

[0252] The solid content concentration of the electrode material film is calculated based on the composition ratio of each component contained in the electrode material film and the specific gravity of these components.

[0253] When a positive electrode layer and a negative electrode layer are produced by the method for producing an electrode layer according to the present invention, a battery is obtained by bonding the obtained positive electrode layer and negative electrode layer together with a separator interposed therebetween.

[0254] Example

[0255] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

[0256] In addition, each process in each example mentioned later was performed in the drying room (low dew point room) of 22 degreeC.

[0257] [Preparation of positive electrode material (P1)]

[0258] (1) LiPF was mixed into a mixture of 45 g of ethylene carbonate (EC), 10 g of propylene carbonate (PC) and 45 g of diethyl carbonate (DEC). 6 (Electrolyte) 13.4 g, and 2.3 g of vinylene carbonate (VC) were further mixed. 64 g of the obtained 115.7 g mixed solution was taken out and this was made into electrolyte solution X1.

[0259] (2) 2 g of a conductive aid (Ketjen black: "Carbon ECP600JD" manufactured by Lion Specialty Chemicals Co., Ltd.) and 174 g of a positive electrode active material (iron phosphate: "LFP NCO M121" manufactured by Alees) were stirred at 1500 rpm (revolutions per minute) for 30 seconds using Awatori Rentaro (manufactured by THINKY CORPORATION) to prepare a kneaded product Y1 (176 g).

[0260] (3) Electrolyte X1 (64 g) was added to kneaded product Y1 (176 g), and the mixture was stirred at 1500 rpm for 120 seconds using Awatori Rentaro (manufactured by THINKY CORPORATION) to obtain a positive electrode material (P1).

[0261] The obtained positive electrode material (P1) was a Bingham fluid having a yield value of 45 kPa, and the volume ratio of the solid component to the liquid component was 48:52.

[0262] [Preparation of current collector foil (S1)]

[0263] Collector foil (S1): A collector foil obtained by thermally bonding a PET film having a thermal bonding layer containing ethylene-vinyl acetate copolymer (EVA) to the back of a positive electrode collector foil (aluminum foil, average thickness 20 μm, Ra 0.5 μm, EAA-218D, carbon-coated product manufactured by Korea JCC).

[0264] The Ra of the current collector mentioned above refers to the arithmetic mean roughness Ra of the surface on which the electrode material film is formed.

[0265] [Preparation of scraper (B1)]

[0266] Scraper (B1): Stainless steel scraper

[0267] [Preparation of tray (P1)]

[0268] Pallet (P1): Figure 2 The tray shown is a laminate of a porous carbon layer with a thickness of 5 mm and a carbon fiber composite material layer with a thickness of 25 mm. The surface is a rectangle of 500 mm (width direction) × 150 mm (length direction). Figure 2 As shown, there is a portion of the air supply slot.

[0269] <Example 1>

[0270] Use as Figure 1 The device shown forms an electrode material film on a collector foil. The collector foil used in Example 1 is a collector foil (S1), and the electrode material is a positive electrode material (P1). In addition, a tray (P1) is used as a tray 10, and a scraper (B1) is used as a molding component 50.

[0271] Specifically, a scraper as the forming member 50 was provided so as to maintain a constant distance of 300 μm from the surface of the collector foil 30 placed on the conveying member 20 formed by connecting the trays 10 .

[0272] The electrode material 40 is supplied onto the collector foil 30, and a reservoir 46 of the electrode material 40 is formed between the collector foil 30 and the forming member 50. Then, the transport member 20 is moved in the Z direction, and the thickness of the electrode material 40 is restricted by the forming member, so that an electrode material film 42 is formed on the collector foil 30.

[0273] In addition, the scraper as the molding member was vibrated by a vibrator. The amplitude of the vibrated scraper was 7 μm and the period was 300 Hz.

[0274] Next, the trays 10 were separated at a speed of 10 mm / sec, and the stacked body 60 of the collector foil 30 and the electrode material film 42 was divided for each tray.

[0275] Next, the tray 10 on which the stacked body 62 of the divided collector foils 32 and the electrode material films 44 were placed was transported in the Z direction, which is the tray connection direction, and the density and thickness of the electrode material films were measured using an X-ray inspection device.

[0276] The density of the electrode material film obtained by X-ray inspection equipment is 2.76 g / cm 3 The thickness (average value) was 310 μm. The solid content concentration of the obtained electrode material film was 47% by volume, and no collapse was observed at the end thereof.

[0277] In the above manner, an electrode layer having a width of 204 mm and a length of 146 mm was obtained.

[0278] In addition, from the information on the density and thickness of the electrode material film obtained using an X-ray inspection device, it was found that the center portion of the electrode material film was 325 μm and was approximately 17 μm thicker than the end portions.

[0279] Therefore, based on this information, the film forming conditions of the electrode material film were changed to reduce the amount of electrode material applied to the central portion of the collector foil by 5%. As a result, an electrode material film with a thickness (average value) of 310 μm and a difference of less than 8 μm between the central thickness and the end thickness in the width direction was formed.

[0280] <Example 2>

[0281] In the same manner as in Example 1, an electrode material film was formed, and the density and thickness of the electrode material film were measured using an X-ray inspection device.

[0282] The density of the electrode material film obtained by X-ray inspection equipment is 2.76 g / cm 3 The thickness (average value) was 310 μm. The solid content concentration of the obtained electrode material film was 47% by volume, and no collapse was observed at the end thereof.

[0283] In addition, from the information on the density and thickness of the electrode material film obtained using an X-ray inspection device, it was found that the end portion of the electrode material film was 295 μm, which was approximately 15 μm thinner than the central portion.

[0284] Therefore, based on this information, the film forming conditions of the electrode material film were changed to increase the amount of electrode material applied to the end of the collector foil by 5%. As a result, an electrode material film with a thickness (average value) of 310 μm and a difference of less than 6 μm between the center thickness and the end thickness in the width direction was formed.

[0285] <Evaluation of thickness uniformity>

[0286] The following information was obtained by measuring the thickness of the electrode material film (width 204 mm, length 146 mm) in each of the above examples using an X-ray measuring device.

[0287] That is, excluding the end portions, the thickness was sampled every 0.5 mm on a line in the width direction, and a total of 400 points were obtained, and the average value A was calculated. In addition, excluding the end portions, the thickness was sampled every 1 mm on a line in the length direction, and a total of 100 points were obtained, and the average value B was calculated.

[0288] By determining whether the two obtained average values ​​A and B are within ±5% of the set target thickness, for example, it is possible to understand the in-plane uniformity of the thickness of the electrode material film.

[0289] Furthermore, if the measurement information of the density using an X-ray measuring device is used, the in-plane uniformity of the density of the electrode material film can be grasped in the same manner as when the measurement information of the thickness is used.

[0290] (Explanation of symbols)

[0291] 10-tray, 12-porous carbon layer, 14-carbon fiber composite material layer, 16-gap portion, 20-conveying component, 30-collector foil, 32-divided collector foil, 40-electrode material, 42-electrode material film, 44-divided electrode material film, 46-storage portion for electrode material, 48-electrode material imparting mechanism, 50-molding component, 60-laminated body, 62-divided laminated body, 70-X-ray inspection device, 80-carrier, 82-guide rail, 84-fixing component, 90-LM guide, X-conveying direction of support body.

[0292] The entire contents of the invention of Japanese Patent Application No. 2022-159831 filed on October 3, 2022 are incorporated into this specification by reference.

[0293] All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each document, patent application, and technical standard was specifically and individually described by reference.

Claims

1. A method for manufacturing an electrode layer, comprising: Step A, using a conveying member formed by connecting a plurality of trays in one direction, to form an electrode material film on a collector foil conveyed along a connecting direction of the trays; Step B, separating the connected trays and dividing the stack of collector foil and electrode material film for each tray; and In step C, the tray on which the stack of the divided collector foil and the electrode material film is placed is conveyed along the connection direction of the trays, and the density and thickness of the electrode material film are measured using an X-ray inspection device.

2. The method for manufacturing an electrode layer according to claim 1, wherein: The tray is a laminate of a porous carbon layer and a carbon fiber composite material layer, and one surface of the porous carbon layer is a contact surface with the current collector foil.

3. The method for manufacturing an electrode layer according to claim 1 or 2, wherein: The total thickness of the pallet is 5mm to 50mm.

4. The method for manufacturing an electrode layer according to claim 1, wherein: The information on the thickness and density of the electrode material film obtained by the X-ray inspection device is fed back to at least one of step A and step B.

5. The method for manufacturing an electrode layer according to claim 4, wherein: At least one of the film forming conditions of the electrode material film in step A and the separation conditions between the trays in step B is controlled based on the fed-back information.

6. The method for manufacturing an electrode layer according to claim 1 or 2, wherein: The electrode material film includes an electrode active material, a conductive auxiliary agent, and an electrolyte solution, has a thickness of 50 μm to 500 μm, and a solid content concentration of 30 volume % to 90 volume %.

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