Method for manufacturing electrode layer

Abstract

A method for manufacturing an electrode layer includes: a step A in which the surface shape of a conveyance member is measured; a step B in which the current collector foil is placed on the conveyance member after the surface shape has been measured, and the current collector foil is conveyed by the movement of the conveyance member; a step C in which an electrode material containing an electrode active material, a conductive auxiliary agent, and an electrolyte solution is supplied onto the conveyed current collector foil; and a step D for forming an electrode material film by passing the electrode material supplied onto the current collector foil through a gap formed by the conveyance member and the tip of a film formation member disposed at a position separated from the surface of the conveyance member to regulate the thickness of the electrode material. The arrangement position of the film forming member is controlled on the basis of the measurement information of the surface shape of the conveying member obtained in step A.

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] Japanese Patent Publication No. 2021-530826 discloses a method for manufacturing a semi-solid electrode, which includes the following steps: continuously disposing a mask material on a collector material; continuously distributing a semi-solid electrode slurry on the collector material; removing the mask material to at least partially define a separate portion of the semi-solid electrode slurry on the collector; and cutting the collector to form a semi-solid electrode. In addition, Patent Document 1 discloses the following: In this method, a scraper is used to spread the semi-solid electrode slurry and the scraper is vibrated.

[0005] Japanese Patent Application No. 2017-533548 discloses the following: As a method for manufacturing an electrochemical cell, the method includes the following steps: a step of arranging a frame defining an opening on the surface of a current collector; a step of arranging a semi-solid anode material in the opening of the frame; and a step of removing excess semi-solid anode material from the opening. In addition, Patent Document 2 discloses the following: removing excess semi-solid anode material with a scraper, and during the removal step, the scraper vibrates. Summary of the invention

[0006] Technical issues to be solved by the invention

[0007] As described in the above-mentioned Japanese Patent Application Publication No. 2021-530826 and Japanese Patent Application Publication No. 2017-533548, there is a method of supplying an electrode material onto a collector foil and flattening the electrode material supplied onto the collector foil using a film forming member to form an electrode material film on the collector foil.

[0008] From the viewpoint of productivity, the above method may employ a method of continuously forming an electrode material film on a current collector foil conveyed by a conveying member.

[0009] However, the conveying member for conveying the collector foil often has corrugations and is not flat. Therefore, depending on the surface shape of the conveying member, the electrode material film formed on the collector foil may have a thickness difference (also called thickness distribution) in the plane.

[0010] Therefore, the present invention has been completed in view of the above circumstances.

[0011] An object of one embodiment of the present invention is to provide a method for producing an electrode layer, which can produce an electrode layer having an electrode material film having excellent in-plane uniformity of thickness.

[0012] Here, the "electrode layer" refers to a laminate of a current collector foil and an electrode material film.

[0013] Means for solving technical problems

[0014] The present invention includes the following aspects.

[0015] <1> A method for manufacturing an electrode layer, comprising:

[0016] Step A, measuring the surface shape of the conveying component;

[0017] Step B, placing a collector foil on the conveying member after measuring the surface shape, and conveying the collector foil by moving the conveying member;

[0018] Step C, supplying an electrode material including an electrode active material, a conductive aid and an electrolyte onto the conveyed collector foil; and

[0019] Step D, forming an electrode material film by allowing the electrode material supplied to the collector foil to pass through a gap formed by a conveying member and a tip of a film forming member disposed at a position separated from a surface of the conveying member to limit the thickness of the electrode material,

[0020] In step D, the arrangement position of the film forming member is controlled based on the measurement information of the surface shape of the transport member obtained in step A.

[0021] <2> The method for producing an electrode layer according to <1>, wherein:

[0022] In step D, the position of the tip of the film forming member is adjusted according to the force applied by the electrode material to the film forming member.

[0023] <3> The method for producing an electrode layer according to <1> or <2>, wherein:

[0024] Using a vibrating film-forming component as the film-forming material,

[0025] In step D, at least one of the frequency and amplitude of the vibration of the film forming member is changed according to the force applied to the film forming member by the electrode material.

[0026] <4> The method for producing an electrode layer according to any one of <1> to <3>, wherein:

[0027] The solid content concentration of the electrode material is 30 volume % to 90 volume %.

[0028] <5> The method for producing an electrode layer according to any one of <1> to <4>, wherein

[0029] When the maximum height of the electrode material supplied in step C is X and the width of the gap formed by the conveying member and the tip of the film forming member disposed at a position separated from the surface of the conveying member is Y, the relationship X>Y is satisfied.

[0030] Effects of the Invention

[0031] According to one embodiment of the present invention, there is provided a method for producing an electrode layer capable of producing an electrode layer having an electrode material film having excellent in-plane uniformity of thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic cross-sectional view for explaining an example of steps A to E in the method for producing an electrode layer according to the present invention.

[0033] Figure 2 This is a schematic cross-sectional view of a scraper as a film-forming member as viewed from the conveying direction of the tray.

[0034] Figure 3 This is a schematic cross-sectional view of a scraper as a film-forming member as viewed from the conveying direction of the tray.

[0035] Figure 4 This is a schematic cross-sectional view of a scraper and a tray as film-forming components as viewed from the side.

[0036] Figure 5 This is a schematic cross-sectional view for explaining a method of adjusting the position of the tip of the film forming member according to the force applied to the film forming member by the electrode material.

[0037] Figure 6 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

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] In the present invention, a combination of two or more preferred aspects or modes becomes a more preferred aspect or mode.

[0043] 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.

[0044] <Method for producing electrode layer>

[0045] The manufacturing method of the electrode layer involved in the present invention is the following manufacturing method of the electrode layer, which includes: step A, measuring the surface shape of the conveying component; step B, placing a collector foil on the conveying component after the surface shape is measured, and conveying the collector foil by moving the conveying component; step C, supplying an electrode material containing an electrode active substance, a conductive additive and an electrolyte to the conveyed collector foil; and step D, allowing the electrode material supplied to the collector foil to pass through a gap formed by the conveying component and the front end of a film-forming component arranged at a position separated from the surface of the conveying component to limit the thickness of the electrode material and form an electrode material film, in which the configuration position of the film-forming component is controlled according to the measurement information of the surface shape of the conveying component obtained in step A.

[0046] Hereinafter, the method for producing an electrode layer according to the present invention will be described by taking as an example a conveying member in which a plurality of trays are connected in one direction.

[0047] When a conveying member formed by connecting a plurality of trays in one direction is used, after forming an electrode material film on the collector foil being conveyed through step D, step E may be included for separating the connected trays and dividing the stack of the collector foil and the electrode material film for each tray.

[0048] In addition, the conveying member is not limited to a conveying member formed by connecting a plurality of trays in one direction.

[0049] 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 70 μm to 230 μm and a solid content concentration of 30 volume % to 90 volume % on a collector foil.

[0050] Here, the thickness of the electrode material film is defined as the arithmetic mean of thicknesses at three locations measured by cross-sectional observation. A known microscope (eg, a scanning electron microscope) can be used for cross-sectional observation.

[0051] 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.

[0052] As described above, there is a method of continuously forming an electrode material film on a collector foil by supplying an electrode material to a collector foil being transported and flattening the electrode material supplied to the collector foil using a film forming member. However, depending on the surface shape of the transport member that transports the collector foil, a thickness difference (also referred to as thickness distribution) may occur within the surface of the electrode material film formed on the collector foil.

[0053] Therefore, the present inventors discovered a method of forming an electrode material film with excellent thickness uniformity by measuring the surface shape of the conveying member in advance and controlling the configuration position of the front end of the film forming member based on the measurement information, thereby completing the above-mentioned method for manufacturing the electrode layer involved in the present invention.

[0054] Japanese Patent Publication No. 2021-530826 does not pay any attention to the surface shape of the member for conveying the collector foil, and does not describe the content of controlling the arrangement position of the film forming member. In addition, Japanese Patent Publication No. 2017-533548 does not mention the content of conveying the collector foil.

[0055] Hereinafter, each step of the method for producing an electrode layer according to the present invention will be described.

[0056] refer to Figure 1 An example of step A to step D will be described.

[0057] like Figure 1 As shown, in step A, the surface shape of the tray 10 constituting the conveying member 12 is measured using the surface shape measuring device 20. Here, the surface shape of the tray 10 with the collector foil 30 placed on the surface of the tray 10 is measured.

[0058] Next, in step B, the collector foil 30 is placed on the conveying member 12 formed by connecting the trays 10 whose surface shapes have been measured in one direction, and the conveying member 12 is moved to convey the collector foil 30 in the Z direction (also called the MD direction). The Z direction also corresponds to the connecting direction of the trays.

[0059] Next, in step C, the electrode material 40 including the electrode active material, the conductive auxiliary agent, and the electrolyte solution is supplied from the supply device 50 onto the conveyed collector foil 30 .

[0060] Then, the electrode material 40 supplied onto the collector foil 30 passes through a gap formed by the conveying member 12 and the tip of a scraper 60 as a film forming member disposed at a position separated from the surface of the conveying member 12 to limit the thickness of the electrode material 40 and form an electrode material film 42 .

[0061] Through the above steps, a laminate 70 of the collector foil 30 and the electrode material film 42 is formed on the tray 10 of the conveying member 12. Figure 1 The Z direction in FIG. 1 also corresponds to the conveying direction of the collector foil 30 , the tray 10 , and the conveying member 12 connecting the tray 10 and the like.

[0062] In step D, the configuration position of the front end of the scraper 60 (also referred to as the front end position of the scraper 60) is controlled based on the measurement information of the surface shape of the conveying member 12 obtained in step A. Thus, the distance of the gap can be adjusted according to the surface shape of the conveying member 12, and as a result, the electrode material film 42 having excellent in-plane uniformity of thickness is formed on the collector foil 30.

[0063] Hereinafter, step A to step D will be described respectively.

[0064] [Process A]

[0065] In step A, the surface shape of the conveying member is measured.

[0066] Hereinafter, a conveying member in which a plurality of trays are connected in one direction will be described.

[0067] (Measurement of surface shape)

[0068] The surface shape of the conveying member (e.g., tray) measured in step A is the corrugation of the surface on which the collector foil is placed, the inclination of the tray (in the width direction, in the length direction), etc. From the viewpoint of improving the uniformity of the thickness of the electrode material film, it is preferred to measure the surface shape of the tray with the collector foil placed thereon.

[0069] In the measurement of such a surface shape, for example, a non-contact type device such as a laser displacement meter, a confocal laser optical system, a multi-color laser coaxial displacement meter, or a white interferometer is preferably used.

[0070] The surface shape may be measured by online inspection or offline inspection, or a combination of these.

[0071] In this way, the surface shape can be obtained as the height information of the tray.

[0072] The measurement target position is the entire region on the surface of the tray where the collector foil is placed.

[0073] Furthermore, if the measurement position is in the width direction of the tray (a direction perpendicular to the conveying direction), it is preferably set to two or more points. In the case of a more detailed measurement, it can be set to three or more points. As specific measurement positions, for example, in the width direction of the tray, three points can be cited, namely, the center and both ends of the area contacted by the collector foil. By measuring these three points, the inclination in the width direction of the tray is measured. Furthermore, two points in the width direction of the tray can also be set as measurement positions. In this case, as the two-point measurement position, it is preferably set as described later. Figure 2 The two points of connection between the film forming part and the piezoelectric actuator shown in the figure are coaxial. That is, the measurement position in the width direction of the tray can be determined according to the number of connection points between the film forming part and the piezoelectric actuator. In this case, the number m of connection points between the film forming part and the piezoelectric actuator and the number n of measurement positions in the width direction of the tray can be the same number (m=n) or m-1=n.

[0074] Furthermore, it is preferable to perform measurement at, for example, 0.1 mm to 10 mm intervals (specifically, 1 mm intervals) at the measurement positions in the conveyance direction (ie, the connection direction) of the trays.

[0075] By measuring the surface shape at the above-mentioned measurement position, the position information of the pallet and the height information of the pallet can be measured in synchronization. For the control of this measurement, for example, a PLC (Programmable Logic Controller) is used.

[0076] (Pallets and conveyor components)

[0077] The tray and conveying member used in step A will be described.

[0078] It is desirable that the tray has mechanical strength as a transport member and adsorptivity of the collector foil and mechanical strength required for forming an electrode material film.

[0079] As a tray having the above-mentioned characteristics, for example, a laminate of a porous layer having one surface as a contact surface with a collector foil and a base layer ensuring mechanical strength is preferable.

[0080] The porous layer in the tray is preferably a layer having continuous (connected) pores in the base material. With the presence of such pores, the collector foil placed on the porous carbon layer can be adsorbed by reducing the pressure in the pores in the porous layer. Therefore, the exposed surface of the porous layer can be set as the contact surface with the collector foil.

[0081] For example, from the viewpoint of being lightweight and having high mechanical strength, the base material of the porous layer is preferably composed of a carbon material. That is, the porous layer is preferably a porous carbon layer called porous carbon.

[0082] The thickness of the porous layer (preferably a porous carbon layer) is preferably 3 mm to 15 mm, more preferably 5 mm to 10 mm, from the viewpoint of mechanical strength.

[0083] The base material layer in the tray is a layer provided adjacent to the porous layer, and its material is not particularly limited. For example, from the viewpoint of being lightweight and having high mechanical strength, a carbon fiber composite material layer is preferred.

[0084] The carbon fiber composite material layer is a layer formed of a composite material (i.e., a carbon fiber composite material) including a parent material (i.e., a matrix) and carbon fibers. 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. Examples of the parent material include thermosetting resins (e.g., epoxy resins) and resins obtained by carbonizing the resins.

[0085] From the viewpoint of mechanical strength, the thickness of the base material layer (preferably the carbon fiber composite material layer) is preferably 5 mm to 30 mm, more preferably 15 mm to 25 mm.

[0086] Preferably, the tray is provided with a gap portion adjacent to the porous layer. The gap portion is connected to a vacuum pump or the like via an air intake hole leading to the outside of the tray, so that the gap portion and the pores of the porous layer can be decompressed. By decompressing the pressure, the collector foil can be adsorbed on the exposed surface of the porous layer.

[0087] From the viewpoint of mechanical strength, the total thickness of the tray is preferably 5 mm to 50 mm, more preferably 25 mm to 35 mm.

[0088] In process A, if Figure 1The surface shape of the tray is measured as shown in FIG. The measured trays are connected in one direction to form a conveying member for conveying the collector foil.

[0089] refer to Figure 6 The connection of the tray will be described.

[0090] like Figure 6 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.

[0091] [Process B]

[0092] In step B, the collector foil is placed on the conveying member after the surface shape has been measured, and the collector foil is conveyed by the movement of the conveying member.

[0093] As described above, the trays whose surface shapes were measured in step A are connected in one direction to form a conveying member for conveying the collector foil. The collector foil is placed on the obtained conveying member, and the collector foil is conveyed as the conveying member with the collector attracted thereto moves.

[0094] (Conveying speed)

[0095] The conveyance speed of the collector foil is not particularly limited, and the conveyance speed may be set according to the film formation speed in step C described later.

[0096] As the conveying speed of the collector foil, for example, 10 mm / sec to 500 mm / sec is selected.

[0097] The conveying movement mechanism of the conveying member is not particularly limited. Figure 6 As 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.

[0098] [Process C]

[0099] In step C, an electrode material including an electrode active material, a conductive auxiliary agent, and an electrolyte solution is supplied onto the conveyed current collector foil.

[0100] As described above, a desired amount of electrode material is supplied to the collector foil whose conveyance has started in step B.

[0101] (Supply device)

[0102] As the device for supplying the electrode material onto the collector foil, for example, any device that supplies the electrode material onto the collector foil intermittently or continuously may be used.

[0103] Examples of the supply device include a hopper, a screw feeder, a pan feeder, and a vibrating feeder.

[0104] When supplying the electrode material onto the collector foil, a limiting frame may be used from the viewpoint of uniformly supplying the electrode material. The limiting frame is placed on the tray and can prevent the electrode material from overflowing outside the collector foil.

[0105] The amount of the electrode material supplied onto the current collector foil is not particularly limited and may be appropriately determined according to the amount of the electrode material film to be formed.

[0106] However, from the viewpoint of effectively forming an electrode material film from the electrode material supplied to the collector foil using a film-forming component in the later-described step D, when the maximum height of the electrode material supplied in this step is set to X, and the width of the gap formed by the conveying component and the front end of the film-forming component arranged at a position separated from the surface of the conveying component in step D is set to Y, it is preferred to satisfy the relationship X>Y.

[0107] The electrode material including the electrode active material, the conductive auxiliary agent and the electrolyte solution used in this step will be described later.

[0108] [Process D]

[0109] In step D, the electrode material supplied onto the collector foil is passed through a gap formed by a conveying member and a tip of a film forming member disposed at a position separated from the surface of the conveying member to limit the thickness of the electrode material and form an electrode material film.

[0110] In addition, in step D, the arrangement position of the film forming member is controlled based on the measurement information of the surface shape of the transport member obtained in step A.

[0111] like Figure 1 As shown, a reservoir 46 formed of the electrode material 40 supplied to the collector foil 30 is formed between the collector foil 30 and the scraper 60. In this state, the collector foil 30 is transported and moved in the Z direction by the transport member 12, and the electrode material 40 passes through the gap between the scraper 60 and the surface of the transport member 12. As the electrode material 40 passes through the gap, the thickness of the electrode material 40 is limited by the gap, and 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.

[0112] (Control of the arrangement position of the film forming component and its front end)

[0113] use Figure 2 The film forming member used in this process and the control of the configuration position of the front end thereof are described below. Figure 2 This is a schematic cross-sectional view of a scraper as a film-forming member as viewed from the conveying direction of the tray.

[0114] like Figure 2 As shown, for example, two piezoelectric actuators 62 are connected to the scraper 60 , and two ball screws 64 are connected to the piezoelectric actuators 62 via connecting portions 66 .

[0115] One end of the ball screw 64 is connected to the drive shaft of the stepping motor (not shown), and the rotational driving force of the stepping motor is transmitted to the ball screw 64. Therefore, the ball screw 64 receives the rotational driving force transmitted from the stepping motor and rotates, and the configuration position of the front end of the scraper 60 can be adjusted according to the rotation.

[0116] The piezoelectric actuator 62 is a so-called piezoelectric element that deforms and displaces when a voltage is applied, and expands and contracts on the order of μm by a change in the applied voltage. By utilizing this expansion and contraction, the position of the tip of the scraper 60 can be adjusted.

[0117] As described above, the piezoelectric actuator 62 and the ball screw 64 (and the stepping motor connected thereto) are components capable of adjusting the position of the tip of the scraper 60. By using at least one of the piezoelectric actuator 62 and the ball screw 64, the position of the tip of the scraper 60 can be adjusted.

[0118] In addition, when the surface shape of the tray 10 does not have a large height difference or the allowable thickness deviation of the electrode material film is large, one of the piezoelectric actuator 62 and the ball screw 64 for adjusting the configuration position of the front end of the scraper 60 can be omitted.

[0119] The arrangement position of the front end of the film forming member is controlled by, for example, a PLC.

[0120] As described above, the PLC plots the position of the tray on the X coordinate and the height of the tray on the Y coordinate (equivalent to the surface position of the collector foil adsorbed to the tray) based on the measurement results obtained by synchronizing the position information of the tray with the height information of the tray. In addition, the PLC recognizes the front end position of the film forming component as the position information of the ball screw 64.

[0121] The PLC sends a control signal to synchronize the relative change of the Y coordinate with the position of the tray in the X coordinate to move the tip position of the film forming member up and down, thereby forming a gap along the surface shape of the tray.

[0122] Below, use Figure 3 An example of a method for adjusting the configuration position of the front end of the scraper is described. Figure 3 This is a schematic cross-sectional view of a scraper as a film-forming member as viewed from the conveying direction of the tray.

[0123] like Figure 3 As shown, when the surface shape of the pallet 10 constituting the conveying component has an upward right inclination, the configuration position of the front end of the scraper 60 is matched with the surface shape of the pallet 10 by shortening the right ball screw 64 and extending the left ball screw 64.

[0124] By doing so, it is possible to make uniform the gap formed by the tray 10 as the conveying member and the tip of the scraper 60 disposed at a position separated from the surface thereof.

[0125] As a result, regardless of the surface shape of the tray 10 , an electrode material film having excellent thickness uniformity can be obtained.

[0126] And, use Figure 4 Another example of a method for adjusting the configuration position of the scraper is described. Figure 4 This is a schematic cross-sectional view of a scraper and a tray as film-forming components as viewed from the side.

[0127] like Figure 4 As shown, when the surface shape of the pallet 10 constituting the conveying member is inclined in an arc shape toward the conveying direction, the two ball screws 64 are extended and retracted while changing the setting position along the surface shape of the pallet to match the surface shape of the pallet 10.

[0128] By doing so, the gap formed by the tray 10 as a conveying member and the tip of the scraper 60 disposed at a position away from the surface can be made uniform. As a result, an electrode material film with excellent thickness uniformity can be obtained regardless of the surface shape of the tray 10.

[0129] In the above two examples, the method of using the ball screw 64 to adjust the configuration position of the front end of the scraper 60 is mainly described, but it is also possible to further improve the uniformity of the gap formed by the tray 10 as a conveying part and the front end of the scraper 60 configured at a position separated from its surface by changing the offset value of the piezoelectric actuator 62 in addition to the extension and contraction of the ball screw 64.

[0130] By utilizing the extension and contraction of the ball screw 64 , the arrangement position of the tip of the scraper 60 can be adjusted by approximately 20 μm to 100 μm.

[0131] Furthermore, by adjusting the offset value of the piezoelectric actuator 62 (specifically, adjustment based on a change in the length of the piezoelectric element (ie, expansion and contraction of the piezoelectric element)), the arrangement position of the tip of the scraper 60 can be adjusted by approximately ±5 μm.

[0132] In step D, the front end position of the film forming member can also be adjusted according to the force applied by the electrode material to the film forming member. As described later, the electrode material is a material containing a large amount of solid components, so the viscosity is high. Therefore, the force to squeeze and expand the gap is applied from the electrode material in contact to the scraper as the film forming member. In particular, in the case where a large amount of electrode material is locally supplied to the collector foil, there is a tendency for the force to squeeze and expand the gap to become larger.

[0133] Therefore, as described above, it is preferable to adjust the front end position of the film forming member according to the force applied to the film forming member by the electrode material.

[0134] In order to adjust the tip position of the film forming member at this time, it is preferable to use a piezoelectric actuator because the piezoelectric actuator can quickly adjust the tip position of the film forming member by changing the applied voltage.

[0135] use Figure 5 A method of adjusting the position of the tip of the film forming member according to the force applied to the film forming member by the electrode material will be described.

[0136] like Figure 5 As shown, when force is applied to the scraper 60 from the electrode material in direction A, causing the gap to be squeezed and expanded, the piezoelectric actuator 62 on the right is quickly extended in direction B to adjust the front end position of the scraper 60 to the position before being squeezed and expanded.

[0137] This can suppress the change in thickness of the electrode material film caused by the expansion of the voids due to compression.

[0138] A vibrating film-forming member can be used in step D. That is, a vibrating film-forming member such as a scraper can be used.

[0139] For example, the vibration of the scraper 60 is transmitted to the electrode material 40, and the shear force is applied, which may reduce the viscosity of the electrode material 40, improve the fluidity, etc. As a result, as described above, at least the surface of the electrode material film 42 formed by applying it on the collector foil 30 becomes flat, and it is easy to form an electrode material film 42 with less thickness deviation.

[0140] Furthermore, when the film forming member (specifically, the scraper) vibrates, it is preferable to change at least one of the frequency and amplitude of the vibration of the film forming member according to the force applied to the film forming member by the electrode material.

[0141] In order to adjust the frequency and amplitude of the vibration of the film-forming member at this time, it is preferable to use a piezoelectric actuator.

[0142] As described above, by vibrating the film forming member, the viscosity of the electrode material can be reduced and the fluidity can be improved. Therefore, for example, as described above, when a force is applied from the electrode material in contact to the scraper as the film forming member, causing the gap to be squeezed and expanded, the viscosity of the electrode material can be reduced and the fluidity can be further improved by increasing at least one of the vibration frequency and amplitude of the film forming member, so that the front end position of the film forming material can be quickly returned to the position before being squeezed and expanded.

[0143] This can suppress the change in thickness of the electrode material film caused by the expansion of the voids due to compression.

[0144] The adjustment of the tip position of the film forming material by the piezoelectric actuator and the adjustment of the frequency and amplitude of the vibrating film forming material are performed as follows.

[0145] A strain gauge is installed on the scraper as the film forming member to detect the force received from the electrode material (specifically, the vertical stress received from the electrode material). Thus, if it is detected that the gap is squeezed and expanded due to the force received from the electrode material, the offset value of the piezoelectric actuator and at least one of the frequency and amplitude of the vibrating film forming material are adjusted based on the information.

[0146] To explain more specifically, the piezoelectric actuator is compressed and contracted by the force received from the electrode material, thereby detecting a state in which the gap is squeezed and expanded.

[0147] If the electrode material in contact with the film-forming material increases and the force received from the electrode material becomes stronger, the amount of contraction of the piezoelectric actuator increases, the gap is expanded, and as a result, the thickness of the electrode material film increases. Therefore, when it is detected that the gap is squeezed and expanded, it is preferred to apply stronger energy to the electrode material in the area to suppress the thickness variation of the electrode material film. As specific schemes, 1. lengthening the overall length of the piezoelectric actuator to reduce the expanded gap, 2. increasing the number of vibrations of the film-forming material (i.e., increasing the frequency), and 3. increasing the vibration amplitude of the film-forming material. By carrying out any of these schemes, the thickness variation of the electrode material film can be suppressed.

[0148] The force received by the electrode material detected by the strain gauge installed on the film forming part is converted into voltage by the dynamic strain gauge (amplifier). The converted voltage waveform is input into a computer such as a PC, and the amplitude, frequency, and phase of the voltage waveform are calculated by the computer in a manner that a control is applied once to a length of about 1 mm in the conveying direction (i.e., MD direction) for the electrode material. The calculated value is transmitted to the PLC, and the difference in the amplitude or frequency of the vibration relative to the set value is corrected by the PLC to become the optimal value (the set gap) when in contact with the electrode material.

[0149] In the above-described manner, the electrode material film is formed on the current collector foil placed on the transport member.

[0150] [Process E]

[0151] The method for producing an electrode layer according to the present invention may include, after step D, step E of separating the connected trays and dividing the stack of the collector foil and the electrode material film for each tray.

[0152] In step E, the long strip of electrode material film formed in step D 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).

[0153] In step E, 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.

[0154] As the separation condition, for example, there can be mentioned the speed or acceleration when the trays are separated.

[0155] It is preferred that the speed or acceleration for separating the trays be reduced as the electrode material film collapses more easily.

[0156] In the above manner, a laminated body ( Figure 1 The electrode layer of the divided stack 72).

[0157] 〔Other processes〕

[0158] The method for producing an electrode layer according to the present invention may include other steps.

[0159] As another step, for example, there is a step of pressurizing the electrode material film.

[0160] (Step of Pressurizing Electrode Material Film)

[0161] The method for producing an electrode layer according to the present invention may include a step of pressurizing the electrode material film.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] 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).

[0168] 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.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] [Current Collector Foil]

[0173] 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.

[0174] Examples of the positive electrode current collector foil include 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.

[0175] As the negative electrode current collector foil, for example, 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.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] The thickness of the collector foil is determined by the same method as the thickness of the electrode material film.

[0183] [Molding parts]

[0184] As the molded component, a scraper can be mentioned.

[0185] As described above, the scraper as a shaped member may vibrate when in contact with the electrode material.

[0186] (Scraper)

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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).

[0191] 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.

[0192] [Electrode materials]

[0193] The electrode material includes an electrode active material, a conductive auxiliary agent, and an electrolyte solution, and may include additives as necessary.

[0194] The solid content concentration of the electrode material is preferably 30% by volume to 90% by volume, and more preferably 40% by volume to 80% by volume.

[0195] (Electrode Active Material)

[0196] 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.

[0197] Examples of the electrode active material include a positive electrode active material and a negative electrode active material.

[0198] -Positive electrode active material-

[0199] 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.

[0200] 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.

[0201] 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).

[0202] 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.

[0203] 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.

[0204] 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.

[0205] Examples of transition metal oxides having a layered rock salt structure include LiCoO2 (lithium cobalt oxide [LCO]), LiNi2O2 (lithium nickel oxide), LiNi 0.85 Co 0.10 Al 0.05 O2 (nickel cobalt aluminum oxide [NCA]), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (lithium nickel manganese cobalt oxide [NMC]) and LiNi 0.5 Mn 0.5 O2 (lithium manganese nickel oxide).

[0206] Examples of transition metal oxides having a spinel structure include LiCoMnO4, Li2FeMn3O8, Li2CuMn3O8, Li2CrMn3O8, and Li2NiMn3O8.

[0207] As lithium-containing transition metal phosphate compounds, for example, olivine-type iron phosphates (for example, LiFePO4 and Li3Fe2(PO4)3), pyrophosphate iron salts (for example, LiFeP2O7), cobalt phosphate salts (for example, LiCoPO4), and monoclinic NASICON-type vanadium phosphate salts (for example, Li3V2(PO4)3 (lithium vanadium phosphate)) can be cited.

[0208] Examples of lithium-containing transition metal halophosphate compounds include iron fluorophosphates (eg, Li2FePO4F), manganese fluorophosphates (eg, Li2MnPO4F), and cobalt fluorophosphates (eg, Li2CoPO4F).

[0209] Examples of lithium-containing transition metal silicate compounds include Li2FeSiO4, Li2MnSiO4, and Li2CoSiO4.

[0210] The transition metal oxide is preferably a transition metal oxide having a layered rock salt structure, more preferably selected from the group consisting of LiCoO2 (lithium cobalt oxide [LCO]), LiNi 0.85 Co 0.10 Al 0.05 O2 (nickel cobalt aluminum oxide [NCA]) and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 At least one compound of the group consisting of O2 (lithium nickel manganese cobalt oxide [NMC]).

[0211] 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.

[0212] Furthermore, the positive electrode active material may have a carbon coating on its surface.

[0213] The shape of the positive electrode active material is not limited, but is preferably in the form of particles from the viewpoint of handleability.

[0214] 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.

[0215] 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.

[0216] The volume average particle size of the positive electrode active material is measured by the following method.

[0217] 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.

[0218] 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.

[0219] The positive electrode active material may be used alone or in combination of two or more.

[0220] 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.

[0221] 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.

[0222] 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.

[0223] -Negative electrode active material-

[0224] 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.

[0225] 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.

[0226] The carbonaceous material is a material substantially composed of carbon.

[0227] 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.

[0228] In the present invention, "flat plate shape" means a shape having two main planes facing in opposite directions.

[0229] As the metal composite oxide, a metal composite oxide capable of occluding and releasing lithium is preferred.

[0230] 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.

[0231] The metal oxide and the metal composite oxide are particularly preferably amorphous oxides.

[0232] 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.

[0233] 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.

[0234] It is also preferred that the negative electrode active material further contains titanium. From the viewpoint of having excellent rapid charge and discharge characteristics due to small volume change during lithium ion storage and release, and being able to increase the life of the lithium ion secondary battery by suppressing electrode degradation, the negative electrode active material containing titanium is preferably Li4Ti5O 12 (lithium titanate [LTO]).

[0235] 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.

[0236] The negative electrode active material can be obtained as, for example, CGB20 (Nippon Graphite Industries Co., Ltd.).

[0237] The composition of the negative electrode active material was measured using inductively coupled plasma (ICP) emission spectrometry.

[0238] 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.

[0239] 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.

[0240] 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.

[0241] Examples of methods for adjusting the particle size of the negative electrode active material include a method using a pulverizer or a classifier.

[0242] The negative electrode active material may be used alone or in combination of two or more.

[0243] 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.

[0244] 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.

[0245] 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.

[0246] 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.

[0247] (Conductive additive)

[0248] 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.

[0249] The conductive auxiliary agent is included in the solid component.

[0250] 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.

[0251] The conductive auxiliary agent may be used alone or in combination of two or more.

[0252] 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.

[0253] 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.

[0254] (Electrolyte)

[0255] 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.

[0256] 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.

[0257] 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.

[0258] As the electrolyte contained in the electrolytic solution, for example, a well-known inorganic solid electrolyte can be used.

[0259] 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.

[0260] 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.

[0261] 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.

[0262] (Solvent)

[0263] 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”).

[0264] 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.

[0265] 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).

[0266] The solvent may be used alone or in combination of two or more.

[0267] 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.

[0268] The content of the liquid component relative to the total volume of the electrode material is preferably 30% by volume to 50% by volume.

[0269] 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.

[0270] (Other ingredients)

[0271] 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.

[0272] Examples of the binder include fluorine-containing resins, hydrocarbon-based thermoplastic resins, acrylic resins, and urethane resins.

[0273] Furthermore, the dispersant may be any known dispersant as long as it can disperse the dispersion object.

[0274] Furthermore, as other additives, known additives added to electrodes can be used.

[0275] <<Electrode layer>>

[0276] 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.

[0277] The sheet-shaped electrode layer is preferably an electrode layer of a semi-solid secondary battery.

[0278] 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.

[0279] The thickness and solid content concentration of the electrode layer are determined by the same method as the thickness and solid content concentration of the electrode material film.

[0280] 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.

[0281] Example

[0282] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

[0283] In addition, each process in each example mentioned later was performed in the drying room (low dew point room) of 22 degreeC.

[0284] [Preparation of positive electrode material (P1)]

[0285] (1) After mixing 13.4 g of LiPF6 (electrolyte) into a mixed solution of 45 g of ethylene carbonate (EC), 10 g of propylene carbonate (PC) and 45 g of diethyl carbonate (DEC), 2.3 g of vinylene carbonate (VC) was also mixed. 64 g of the obtained 115.7 g mixed solution was taken out and used as electrolyte X1.

[0286] (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).

[0287] (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).

[0288] 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.

[0289] [Preparation of current collector foil (S1)]

[0290] 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).

[0291] 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.

[0292] [Preparation of scraper (B1)]

[0293] Scraper (B1): Stainless steel scraper

[0294] [Preparation of tray (P1)]

[0295] Tray (P1): A tray that is a laminate of a 5 mm thick porous carbon layer and a 25 mm thick carbon fiber composite material layer. The surface is a rectangle of 500 mm (width direction) x 150 mm (conveying direction). A portion of the air supply groove is present.

[0296] <Example 1>

[0297] Use as Figure 1 In the device shown, an electrode material film is formed on a current collector foil. In Example 1, a current collector foil (S1) and a positive electrode material (P1) are used, a tray (P1) is used as the tray 10, and a scraper (B1) is used as the scraper 60.

[0298] First, the surface shape of each of the plurality of trays 10 to which the collector foils were fixed was measured using a non-contact laser interferometer.

[0299] The scraper 60 is arranged so as to maintain a certain distance of 200 μm relative to the surface of the collector foil 30 placed on the conveying member 12 connected by the tray 10 after the surface shape is measured. Based on the set position, the arrangement position of the front end of the scraper 60 is set to a position relative to the measured surface shape of the tray 10. Here, the arrangement position of the front end of the scraper 60 is adjusted only by the extension and contraction of the ball screw 64. That is, the arrangement position of the front end of the scraper 60 is adjusted to follow the surface shape of the tray 10 by the extension and contraction of the ball screw 64.

[0300] The electrode material 40 is supplied onto the collector foil 30 using the electrode material supply device 50 to form a reservoir 46 of the electrode material 40 between the collector foil 30 and the scraper 60, and then the conveying member 12 is moved in the Z direction (i.e., MD direction), thereby limiting the thickness of the electrode material 40 by the forming member and forming an electrode material film 42 on the collector foil 30. At this time, the moving speed of the conveying member 12, i.e., the conveying speed of the collector foil, is 10 mm / sec.

[0301] In addition, the scraper as the molding member was vibrated by a piezoelectric actuator. The amplitude of the vibrating scraper was ±3 μm and the period was 600 Hz.

[0302] Next, the trays 10 were separated at a speed of 10 mm / sec, and the stacked body 70 of the collector foil 30 and the electrode material film 42 was divided for each tray.

[0303] The solid content concentration of the obtained electrode material film was 47% by volume.

[0304] In the above-described manner, an electrode layer is obtained.

[0305] <Example 2>

[0306] An electrode layer was obtained in the same manner as in Example 1 except that the arrangement position of the tip of the squeegee 60 was set as follows.

[0307] That is, the configuration position of the front end of the scraper 60 is adjusted by utilizing the expansion and contraction of the ball screw 64 and the expansion and contraction of the piezoelectric element in the piezoelectric actuator 62. That is, in addition to the expansion and contraction of the ball screw 64, the configuration position of the front end of the scraper 60 is adjusted so that it follows the surface shape of the tray 10 by utilizing the expansion and contraction of the piezoelectric element in the piezoelectric actuator 62.

[0308] The solid content concentration of the electrode material film obtained in this example was 47% by volume.

[0309] <Example 3>

[0310] An electrode layer was obtained in the same manner as in Example 2 except that the moving speed of the conveying member 12 during the formation of the electrode material film 42 , that is, the conveying speed of the collector foil was changed to 200 mm / sec.

[0311] The solid content concentration of the electrode material film obtained in this example was 47% by volume.

[0312] <Example 4>

[0313] An electrode layer was obtained in the same manner as in Example 2 except that the moving speed of the conveying member 12 during formation of the electrode material film 42, that is, the conveying speed of the collector foil was changed to 200 mm / sec and the position of the tip of the squeegee 60 was set as follows.

[0314] Hereinafter, setting of the arrangement position of the front end of the scraper 60 will be described in detail.

[0315] The length of the pallet in the conveying direction is set as the reference length L, and the numerical value of the surface shape of one pallet is Fourier transformed to calculate the amplitudes relative to the reference length L, L / 2, L / 3, L / 4, etc. Based on the calculated values, the amplitude of the L cycle (first order component) is adjusted by the expansion and contraction of the ball screw 64, and the amplitude of the L / 4 cycle (fourth order component) is adjusted by the expansion and contraction of the piezoelectric element.

[0316] The solid content concentration of the electrode material film obtained in this example was 47% by volume.

[0317] <Evaluation of thickness uniformity in the plane>

[0318] After the electrode material film was formed, the surface shape of the electrode material film was measured in the same manner as the surface shape of the collector foil.

[0319] The obtained measured values ​​of the surface shape of the electrode material film and the measured values ​​of the surface shape of the collector foil can be associated with the position information of the tray, and the difference at each position is used as the film thickness of the electrode material film. Along the conveying direction, the film thickness of 100 points is extracted every 1mm. The measurement position is set to a line in the center of the width direction of the electrode material film and two lines separated 90mm from the center to the left and right, totaling three lines. Based on the 300 film thickness values ​​of 100 points × three lines, the average value and standard deviation (average value ± standard deviation) are calculated.

[0320] The results are shown below.

[0321] Example 1: 210 μm ± 13 μm

[0322] Example 2: 203 μm ± 3 μm

[0323] Example 3: 201 μm ± 6 μm

[0324] Example 4: 202 μm ± 4 μm

[0325] (Explanation of symbols)

[0326] 10-tray, 12-conveying component, 20-surface shape inspection device, 30-collector foil, 32-divided collector foil, 40-electrode material, 42-electrode material film, 44-divided electrode material film, 46-storage part of electrode material, 50-electrode material supply device, 60-film forming component (scraper), 62-piezoelectric actuator, 64-ball screw, 66-connecting part, 70-stack, 72-divided stack, 80-carrier, 82-guide rail, 84-fixing component, 90-LM guide, Z-conveying direction of conveying component, A-direction of force applied to the scraper from the electrode material, B-direction of stretching the piezoelectric actuator.

[0327] The entire contents of the invention of Japanese Patent Application No. 2022-159830 filed on October 3, 2022 are incorporated into this specification by reference.

[0328] 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, measuring the surface shape of the conveying component; Step B, placing a collector foil on the conveying member after measuring the surface shape, and conveying the collector foil by moving the conveying member; Step C, supplying an electrode material including an electrode active material, a conductive aid and an electrolyte onto the conveyed collector foil; and Step D, allowing the electrode material supplied to the collector foil to pass through a gap to limit the thickness of the electrode material and form an electrode material film, the gap being a gap formed by a conveying member and a tip of a film forming member disposed at a position separated from a surface of the conveying member, In step D, the arrangement position of the film forming member is controlled based on the measurement information of the surface shape of the transport member obtained in step A.

2. The method for manufacturing an electrode layer according to claim 1, wherein: In step D, the position of the tip of the film forming member is adjusted according to the force applied by the electrode material to the film forming member.

3. The method for manufacturing an electrode layer according to claim 1 or 2, wherein: Using a vibrating film-forming component as the film-forming material, In step D, at least one of the frequency and amplitude of the vibration of the film forming member is changed according to the force applied to the film forming member by the electrode material.

4. The method for manufacturing an electrode layer according to claim 1 or 2, wherein: The solid content concentration of the electrode material is 30 volume % to 90 volume %.

5. The method for manufacturing an electrode layer according to claim 1 or 2, wherein: When the maximum height of the electrode material supplied in step C is X and the width of the gap formed by the conveying member and the tip of the film forming member disposed at a position separated from the surface of the conveying member is Y, the relationship X>Y is satisfied.

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