Method for manufacturing electrode layer

Abstract

This method for manufacturing an electrode layer comprises: a step A for measuring the surface shape of a transport member; a step B for placing a current collection foil on the transport member after measuring the surface shape, and transporting the current collection foil by moving the transport member; a step C for supplying an electrode material containing an electrode active material, a conductive assistant, and an electrolyte on the current collection foil being transported; and a step D for forming an electrode material film by passing the electrode material supplied on the current collection foil through a gap formed between the transport member and the tip of a film forming member disposed at a position apart from the transport member surface, and regulating the thickness of the electrode material, and in step D, controls the placement position of the film forming member on the basis of the measurement information of the surface shape of the transport member obtained in step A.

Description

Manufacturing method of electrode layer

[0001] The present disclosure relates to a method for manufacturing an electrode layer.

[0002] In recent years, the development of semi-solid batteries has been under consideration. Electrodes used in semi-solid batteries are manufactured using, for example, an electrode material containing at least an electrode active material in the form of a powder and an electrolyte solution.

[0003] JP 2021-530826 A discloses a method for producing a semi-solid electrode, the method comprising continuously placing a mask material on a current collector material, continuously distributing a semi-solid electrode slurry on the current collector material, removing the mask material to at least partially define separate portions of the semi-solid electrode slurry on the current collector, and cutting the current collector to form a semi-solid electrode. Patent Document 1 also discloses spreading the semi-solid electrode slurry with a blade and vibrating the blade in this method.

[0004] JP 2017-533548 A discloses a method for manufacturing an electrochemical cell, which includes the steps of placing a frame defining an opening on a surface of a current collector, placing a semi-solid anode material in the opening of the frame, and removing excess semi-solid anode material from the opening. JP 2017-533548 A also discloses that the excess semi-solid anode material is removed with a doctor blade, and that the doctor blade is vibrated during the removing step.

[0005] As described in the above-mentioned Japanese Patent Publication Nos. 2021-530826 and 2017-533548, there is a method in which an electrode material is supplied onto a current collecting foil and then the electrode material supplied onto the current collecting foil is leveled using a film forming member to form an electrode material film on the current collecting foil. From the viewpoint of productivity, the above method may be replaced by a method in which an electrode material film is continuously formed on the current collecting foil being transported by a transport member. However, the transport member that transports the current collecting foil is often uneven due to undulations or the like. Therefore, depending on the surface shape of the transport member, thickness differences (also referred to as thickness distribution) may occur within the surface of the electrode material film formed on the current collecting foil.

[0006] The present disclosure has been made in view of the above circumstances. An object of one embodiment of the present disclosure is to provide a method for manufacturing an electrode layer that can manufacture an electrode layer having an electrode material film with excellent in-plane thickness uniformity. Here, the term "electrode layer" refers to a laminate of a current collecting foil and an electrode material film.

[0007] The present disclosure includes the following aspects: <1> A method for manufacturing an electrode layer, comprising: step A of measuring the surface shape of a conveying member; step B of placing a current collecting foil on the conveying member after measuring the surface shape and conveying the current collecting foil by moving the conveying member; step C of supplying an electrode material including an electrode active material, a conductive additive, and an electrolyte onto the conveyed current collecting foil; and step D of passing the electrode material supplied onto the current collecting foil through a gap formed between the conveying member and the tip of a film-forming member positioned at a distance from the surface of the conveying member, thereby regulating the thickness of the electrode material to form an electrode material film, wherein in step D, the position of the film-forming member is controlled based on measurement information about the surface shape of the conveying member obtained in step A.

[0008] <2> The method for producing an electrode layer according to <1>, wherein in step D, the tip position of the film-forming member is adjusted according to the force exerted by the electrode material on the film-forming member. <3> The method for producing an electrode layer according to <1> or <2>, wherein a vibrating film-forming member is used as the film-forming material, and in step D, at least one of the frequency and amplitude of vibration of the film-forming member is changed according to the force exerted by the electrode material on the film-forming member. <4> The method for producing an electrode layer according to any one of <1> to <3>, wherein the solid component concentration of the electrode material is 30% by volume to 90% by volume. <5> The method for producing an electrode layer according to any one of <1> to <4>, wherein when X is the maximum height of the electrode material supplied in step C and Y is the width of a gap formed between the transport member and the tip of the film-forming member arranged at a position spaced apart from the surface of the transport member, the relationship X>Y is satisfied.

[0009] According to one embodiment of the present disclosure, it is possible to provide a method for manufacturing an electrode layer that can manufacture an electrode layer having an electrode material film with excellent in-plane thickness uniformity.

[0010] FIG. 1 is a schematic cross-sectional view illustrating an example of steps A to E in the manufacturing method of an electrode layer according to the present disclosure. FIG. 2 is a schematic cross-sectional view illustrating a blade serving as a film-forming member, as viewed from the conveying direction of a pallet. FIG. 3 is a schematic cross-sectional view illustrating a blade serving as a film-forming member, as viewed from the conveying direction of a pallet. FIG. 4 is a schematic cross-sectional view illustrating a blade serving as a film-forming member and a pallet, as viewed from the side. FIG. 5 is a schematic cross-sectional view illustrating a method for adjusting the tip position of a film-forming member in accordance with the force exerted by an electrode material on the film-forming member. FIG. 6 is a schematic cross-sectional view illustrating an example of a conveying member used in the manufacturing method of an electrode layer according to the present disclosure.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the object of the present disclosure. Components indicated by the same reference numerals in the drawings are the same components. Descriptions of duplicated components and reference numerals in the drawings may be omitted. The dimensional ratios in the drawings do not necessarily represent the actual dimensional ratios.

[0012] In this disclosure, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the upper and lower limits. In the numerical ranges described in this disclosure in stages, the upper or lower limit described in a certain numerical range may be replaced with the upper or lower limit of another staged numerical range. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit described in a certain numerical range may be replaced with a value shown in the Examples. In this disclosure, the term "step" includes not only independent steps, but also steps that cannot be clearly distinguished from other steps, as long as the intended purpose of the step is achieved. In this disclosure, when multiple substances corresponding to each component are present in the composition, the amount of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified. In this disclosure, a combination of two or more preferred embodiments or forms is a more preferred embodiment or form. In this disclosure, a "solid component" means a component that is solid at 25°C and 1 atmosphere, and a "liquid component" means a component that is liquid at 25°C and 1 atmosphere.

[0013] <Method for manufacturing electrode layer> The method for manufacturing an electrode layer according to the present disclosure includes: step A of measuring the surface shape of a conveying member; step B of placing a current collecting foil on the conveying member after measuring the surface shape and conveying the current collecting foil by moving the conveying member; step C of supplying an electrode material containing an electrode active material, a conductive additive, and an electrolyte solution onto the conveyed current collecting foil; and step D of passing the electrode material supplied onto the current collecting foil through a gap formed between the conveying member and the tip of a film-forming member positioned at a distance from the surface of the conveying member, thereby regulating the thickness of the electrode material to form an electrode material film, wherein in step D, the position of the film-forming member is controlled based on the measurement information of the surface shape of the conveying member obtained in step A.

[0014] Hereinafter, the method for manufacturing an electrode layer according to the present disclosure will be described using, as an example, a conveying member in which a plurality of pallets are connected in one direction. When a conveying member in which a plurality of pallets are connected in one direction is used, after the electrode material film is formed on the current collecting foil being conveyed through step D, the method may further include step E in which the connected pallets are separated from each other to divide the laminate of the current collecting foil and the electrode material film into individual pallets. Note that the conveying member is not limited to a conveying member in which a plurality of pallets are connected in one direction.

[0015] In the present disclosure, the electrode material film preferably contains an electrode active material, a conductive additive, and an electrolyte solution, has a thickness of 50 μm to 500 μm, and has a solid component concentration of 30% to 90% by volume. In other words, the method for producing an electrode layer according to the present disclosure preferably forms, on a current collector foil, an electrode material film having a thickness of 70 μm to 230 μm and a solid component concentration of 30% to 90% by volume.

[0016] Here, the thickness of the electrode material film is the arithmetic mean value of the thicknesses measured at three locations by cross-sectional observation. A known microscope (e.g., a scanning electron microscope) can be used for the cross-sectional observation. The solid component concentration of the electrode material film is calculated from the composition ratio of each component contained in the electrode material film and the specific gravity of those components.

[0017] As described above, there is a method for continuously forming an electrode material film on a current collecting foil by supplying the electrode material onto the current collecting foil as it is conveyed and then smoothing the electrode material supplied onto the current collecting foil using a film-forming member. However, depending on the surface shape of the conveying member that conveys the current collecting foil, thickness variations (also referred to as thickness distribution) may occur within the surface of the electrode material film formed on the current collecting foil. Therefore, the present inventors have discovered a method for forming an electrode material film with excellent thickness uniformity by measuring the surface shape of the conveying member in advance and controlling the positioning position of the tip of the film-forming member based on this measurement information, and have thus achieved the above-mentioned method for manufacturing an electrode layer according to the present disclosure.

[0018] JP 2021-530826 A does not pay any attention to the surface shape of the member that transports the current collecting foil, nor does it describe controlling the placement position of the film forming member. JP 2017-533548 A also does not mention transporting the current collecting foil.

[0019] Each step of the manufacturing method of an electrode layer according to the present disclosure will be described below. An example of steps A to D will be described with reference to FIG. 1 . As shown in FIG. 1 , in step A, a surface profile measuring device 20 is used to measure the surface profile of a pallet 10 constituting a conveying member 12. Here, the surface profile of a current collector foil 30 placed on the surface of the pallet 10 is measured. Next, in step B, the current collector foil 30 is placed on a conveying member 12 formed by connecting pallets 10 in one direction after the surface profile measurement, and the conveying member 12 is moved to convey the current collector foil 30 along the Z direction (also referred to as the MD direction). The Z direction also corresponds to the direction in which the pallets are connected. Next, in step C, an electrode material 40 containing an electrode active material, a conductive additive, and an electrolyte solution is supplied from a supply device 50 onto the current collector foil 30 being conveyed. Next, the electrode material 40 supplied onto the current collector foil 30 is passed through a gap formed between the conveying member 12 and the tip of a blade 60, which is a film-forming member positioned at a distance from the surface of the conveying member 12, thereby regulating the thickness of the electrode material 40 and forming an electrode material film 42. Through the above steps, a laminate 70 of the current collector foil 30 and the electrode material film 42 is formed on the pallet 10 of the conveying member 12. The Z direction in FIG. 1 also corresponds to the conveying direction of the current collector foil 30, the pallet 10, and the conveying member 12 formed by connecting them. In step D, the position of the tip of the blade 60 (also referred to as the tip position of the blade 60) is controlled based on the measurement information of the surface shape of the conveying member 12 obtained in step A. This allows the gap distance to be adjusted to match the surface shape of the conveying member 12, resulting in the formation of an electrode material film 42 with excellent in-plane thickness uniformity on the current collector foil 30. Each of steps A to D is described below.

[0020] [Step A] In step A, the surface shape of the conveying member is measured. Hereinafter, a conveying member in which a plurality of pallets are connected in one direction will be described.

[0021] (Surface Shape Measurement) The surface shape of the conveying member (e.g., pallet) measured in step A includes the waviness of the surface on which the current collector foil is placed, the inclination of the pallet (in the width direction and length direction), etc. From the viewpoint of improving the uniformity of the thickness of the electrode material film, it is preferable to measure the surface shape of the pallet with the current collector foil placed thereon. For measuring such surface shape, it is preferable to use a non-contact device such as a laser displacement meter, a confocal laser optical system, a multicolor laser coaxial displacement meter, or a white light interferometer. Note that the surface shape may be measured by online inspection, offline inspection, or a combination of these. In this way, the surface shape is obtained as height information of the pallet.

[0022] The measurement target positions are the entire area on the surface of the pallet where the current collector foil is placed. Furthermore, two or more measurement points are preferably measured in the width direction of the pallet (a direction perpendicular to the conveying direction), and three or more measurement points may be used for more detailed measurements. Specific measurement positions include, for example, three points in the width direction of the pallet: the center and both ends of the area where the current collector foil contacts. Measurement at these three points measures the tilt of the pallet in the width direction. Two measurement points in the width direction of the pallet may also be used. In this case, the two measurement points are preferably coaxial with two connection points between the film-forming member and the piezoelectric actuator, as shown in FIG. 2 (described later). In other words, the measurement positions in the width direction of the pallet may be determined according to the number of connection points between the film-forming member and the piezoelectric actuator. In this case, the number m of connection points between the film-forming member and the piezoelectric actuator and the number n of measurement positions in the width direction of the pallet may be the same (m = n), or may be m - 1 = n. Furthermore, it is preferable that the measurement positions in the pallet transport direction (i.e., the connecting direction) be measured at intervals of 0.1 mm to 10 mm, specifically at 1 mm intervals. By measuring the surface shape at the above-mentioned measurement positions, it is possible to measure pallet position information and pallet height information in a synchronized manner. This measurement is controlled using, for example, a PLC (programmable logic controller).

[0023] (Pallet and conveying member) The pallet and conveying member used in step A will be described. The pallet is required to have the mechanical strength required for a conveying member, the ability to attract the current collecting foil, and the mechanical strength required for forming the electrode material film. A pallet having the above properties is preferably, for example, a laminate of a porous layer, one surface of which comes into contact with the current collecting foil, and a base layer that ensures mechanical strength.

[0024] The porous layer in the pallet is preferably a layer having continuous (connected) pores in the matrix material. The presence of such pores allows the current collector foil placed on the porous carbon layer to be adsorbed by reducing the pressure inside the pores in the porous layer. Therefore, the exposed surface of the porous layer can be the contact surface with the current collector foil. For example, from the viewpoint of achieving high mechanical strength while being lightweight, it is preferable that the matrix material of the porous layer be composed of a carbon material. In other words, the porous layer is preferably a porous carbon layer, also known as porous carbon. From the viewpoint of mechanical strength, the thickness of the porous layer (preferably the porous carbon layer) is preferably 3 mm to 15 mm, and more preferably 5 mm to 10 mm.

[0025] The substrate layer of the pallet is a layer provided adjacent to the porous layer, and its material is not particularly limited. For example, from the viewpoint of lightweight yet high mechanical strength, a carbon fiber composite layer is preferable. The carbon fiber composite layer is a layer made of a composite material (i.e., carbon fiber composite material) containing a base material (i.e., matrix) and carbon fibers. Examples of carbon fiber composite materials that constitute the carbon fiber composite layer include carbon fiber reinforced plastic (CFRP) and carbon fiber reinforced carbon composite material (C / C composite). Examples of base materials include thermosetting resins (e.g., epoxy resins) and carbonized versions of these resins. From the viewpoint of mechanical strength, the thickness of the substrate layer (preferably the carbon fiber composite material layer) is preferably 5 mm to 30 mm, and more preferably 15 mm to 25 mm.

[0026] The pallet preferably has a gap adjacent to the porous layer. This gap is connected to a vacuum pump or the like via an air intake opening that leads to the outside of the pallet, allowing the pressure in the gap and the pores of the porous layer to be reduced. This reduced pressure allows the current collector foil to be adsorbed onto the exposed surface of the porous layer.

[0027] From the viewpoint of mechanical strength, the total thickness of the pallet is preferably 5 mm to 50 mm, and more preferably 25 mm to 35 mm.

[0028] In process A, as shown in FIG. 1 , the surface shape of the pallet is measured. The measured pallets are connected in one direction to form a conveying member for conveying current collector foil. Pallet connection will be described with reference to FIG. 6 . As shown in FIG. 6 , a table 80, rails 82 installed on the table 80, and fixing members 84 for fixing the pallets 10 are used to connect multiple pallets 10. The pallets 10 have guide grooves (not shown) on their back surfaces. Multiple pallets 10 are placed on the table 80 by fitting the guide grooves on their back surfaces onto the rails 82. Then, each pallet 10 is slid along the rails 82 in the direction of the arrow, pressing the pallets 10 together and bringing them into close contact. The closely-connected pallets 10 are then fixed together with fixing members 84, resulting in a conveying member in which multiple pallets 10 are connected in one direction.

[0029] [Step B] In step B, the current collecting foil is placed on the conveying member after the surface shape has been measured, and the current collecting foil is conveyed by moving the conveying member. As described above, the pallets whose surface shape has been measured in step A are connected in one direction to become the conveying member for conveying the current collecting foil. The current collecting foil is placed on the obtained conveying member, and as the conveying member that adsorbs the current collector moves, the current collecting foil is also conveyed.

[0030] (Transportation Speed) The transport speed of the current collector foil is not particularly limited, and may be set depending on the film formation speed in the step C described below. The transport speed of the current collector foil is selected to be, for example, 10 mm / sec to 500 mm / sec.

[0031] There are no particular limitations on the means for transporting and moving the transport member. For example, as shown in Fig. 6, a transport member to which a plurality of pallets 10 are connected is transported by moving the table 80 with the table 80 still mounted on it using a linear motion guide (LM) 90 or the like.

[0032] [Step C] In step C, an electrode material containing an electrode active material, a conductive additive, and an electrolyte solution is supplied onto the current collecting foil to be conveyed. As described above, a desired amount of electrode material is supplied onto the current collecting foil whose conveyance has started in step B.

[0033] (Supplying Device) The supplying device for the electrode material onto the current collecting foil may be, for example, a device that supplies the electrode material intermittently or continuously onto the current collecting foil. Examples of the supplying device include a hopper, a screw feeder, a disk feeder, and a vibrating feeder. When supplying the electrode material onto the current collecting foil, a regulating frame may be used to ensure uniform supply of the electrode material. The regulating frame is placed on a pallet and can prevent the electrode material from leaking outside the current collecting foil.

[0034] The amount of electrode material supplied onto the current collecting foil is not particularly limited and may be determined appropriately depending on the amount of electrode material film formed. However, from the viewpoint of efficiently forming an electrode material film from the electrode material supplied onto the current collecting foil using a film-forming member in step D described below, it is preferable to satisfy the relationship X>Y, where X is the maximum height of the electrode material supplied in this step and Y is the width of the gap formed in step D between the conveying member and the tip of the film-forming member arranged at a position spaced from the surface of the conveying member.

[0035] The electrode materials used in this step, including the electrode active material, the conductive additive, and the electrolyte, will be described later.

[0036] In step D, the electrode material supplied onto the current collector foil is passed through a gap formed between the conveying member and the tip of a film-forming member disposed at a position spaced apart from the surface of the conveying member, and the thickness of the electrode material is regulated to form an electrode material film. Note that in step D, the placement position of the film-forming member is controlled based on the measurement information of the surface shape of the conveying member obtained in step A.

[0037] 1 , a reservoir 46 is formed between the current collector foil 30 and the blade 60 by the electrode material 40 supplied on the current collector foil 30. In this state, by transporting the current collector foil 30 in the Z direction by the transport member 12, the electrode material 40 passes through the gap between the blade 60 and the surface of the transport member 12. As the electrode material 40 passes through this gap, the thickness of the electrode material 40 is restricted by this gap, and further, the electrode material 40 is applied to the surface of the current collector foil 30, and an electrode material film 42 made of the electrode material 40 is formed on the current collector foil 30.

[0038] (Control of the Position of the Film-Depositing Member and Its Tip) The control of the position of the film-depositing member and its tip used in this process will be described with reference to FIG. 2 . Here, FIG. 2 is a schematic cross-sectional view of a blade, which is a film-depositing member, viewed from the conveying direction of the pallet. As shown in FIG. 2 , for example, two piezo actuators 62 are connected to the blade 60, and two ball screws 64 are connected to the piezo actuators 62 via connectors 66. One end of the ball screw 64 is coupled to the drive shaft of a stepping motor (not shown), and the rotational drive force of the stepping motor is transmitted to the ball screw 64. Therefore, the ball screw 64 rotates upon receiving the rotational drive force transmitted from the stepping motor, and the position of the tip of the blade 60 can be adjusted in accordance with this rotation. The piezo actuator 62 is a so-called piezoelectric element that distorts and generates displacement when a voltage is applied, and expands and contracts on the order of μm with changes in the applied voltage. This expansion and contraction can be used to adjust the position of the tip of the blade 60.

[0039] 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 blade 60. The position of the tip of the blade 60 can be adjusted by using at least one of the piezoelectric actuator 62 and the ball screw 64. Note that if there is no significant difference in height on the surface shape of the pallet 10, or if there is a large tolerance for variation in the thickness of the electrode material film, one of the piezoelectric actuator 62 and the ball screw 64, which adjust the position of the tip of the blade 60, can be omitted.

[0040] The position of the tip of the film-forming member is controlled, for example, by a PLC. As described above, the PLC plots the position of the pallet on the X coordinate and the height of the pallet (corresponding to the surface position of the current collecting foil attracted to the pallet) on the Y coordinate based on the measurement results obtained by synchronizing the pallet position information and the pallet height information. The PLC also recognizes the tip position of the film-forming member as position information of the ball screw 64. The PLC synchronizes the relative fluctuation of the Y coordinate with the pallet position on the X coordinate and sends a control signal to raise or lower the tip position of the film-forming member, thereby creating a gap that follows the surface shape of the pallet.

[0041] An example of a method for adjusting the position of the blade tip will be described below with reference to FIG. 3 . Here, FIG. 3 is a schematic cross-sectional view of a blade, which is a film-forming member, viewed from the pallet transport direction. As shown in FIG. 3 , when the surface shape of the pallet 10 constituting the transport member has an upward slope to the right, the position of the tip of the blade 60 is adjusted to the surface shape of the pallet 10 by shortening the ball screw 64 on the right side and extending the ball screw 64 on the left side. This makes it possible to uniformize the gap formed between the pallet 10, which is the transport member, and the tip of the blade 60, which is positioned at a distance from its surface. As a result, an electrode material film with excellent thickness uniformity can be obtained regardless of the surface shape of the pallet 10.

[0042] Another example of a method for adjusting the blade position will be described with reference to FIG. 4 . Here, FIG. 4 is a schematic cross-sectional view of the blade and pallet, which are film-forming members, viewed from the side. As shown in FIG. 4 , when the surface shape of the pallet 10, which constitutes the conveying member, is inclined in an arc shape toward the conveying direction, the two ball screws 64 are extended and retracted while changing their installation positions along the surface shape of the pallet, thereby adjusting the shape to the surface shape of the pallet 10. In this way, the gap formed between the pallet 10, which is the conveying member, and the blade 60 positioned at a distance from its 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 pallet 10.

[0043] In the two examples above, we have mainly described a method of adjusting the position of the tip of the blade 60 using the ball screw 64. However, in addition to expanding and contracting the ball screw 64, the offset value of the piezoelectric actuator 62 may be changed to further uniformize the gap formed between the pallet 10 (the conveying member) and the tip of the blade 60 positioned at a distance from its surface. By using the expansion and contraction of the ball screw 64, the position of the tip of the blade 60 can be adjusted by approximately 20 μm to 100 μm. Furthermore, by adjusting the offset value of the piezoelectric actuator 62 (specifically, by changing the length of the piezoelectric element (i.e., by expanding and contracting the piezoelectric element)), the position of the tip of the blade 60 can be adjusted by approximately ±5 μm.

[0044] In step D, the tip position of the film-forming member can also be adjusted depending on the force exerted by the electrode material on the film-forming member. As described below, the electrode material contains a large amount of solid components and therefore has high viscosity. Therefore, the electrode material in contact with the blade, which is the film-forming member, exerts a force that tries to expand the gap. This force tends to be particularly strong when too much electrode material is supplied locally onto the current collector foil. Therefore, as described above, it is preferable to adjust the tip position of the film-forming member depending on the force exerted by the electrode material on the film-forming member. In this case, it is preferable to use a piezoelectric actuator to adjust the tip position of the film-forming member. This is because the piezoelectric actuator can quickly adjust the tip position of the film-forming member by changing the applied voltage.

[0045] 5, a method for adjusting the tip position of the film-forming member in accordance with the force exerted by the electrode material on the film-forming member will be described. As shown in FIG. 5, when a force is applied from the electrode material to the blade 60 in direction A, causing the gap to be expanded, the right-side piezo actuator 62 is quickly extended in direction B to adjust the tip position of the blade 60 back to the position before the expansion. This makes it possible to suppress changes in the thickness of the electrode material film caused by the expansion of the gap.

[0046] In step D, a vibrating film-forming member can be used. That is, a vibrating blade can be used as the blade film-forming member. For example, when the blade 60 is vibrating, the vibrations are transmitted to the electrode material 40, and a shear force is applied, which may result in a decrease in viscosity of the electrode material 40 and an increase in fluidity. As a result, at least the surface of the electrode material film 42 formed by spreading on the current collector foil 30 as described above has a uniform surface shape, making it easier to form an electrode material film 42 with little variation in thickness.

[0047] Furthermore, when the film-forming member (specifically, a blade) is vibrating, it is preferable to change at least one of the frequency and amplitude of the vibration of the film-forming member depending on the force exerted by the electrode material on the film-forming member. In this case, a piezoelectric actuator is preferably used to adjust the frequency and amplitude of the vibration of the film-forming member. As described above, vibrating the film-forming member can reduce the viscosity and improve the fluidity of the electrode material. Therefore, for example, if the blade, which is the film-forming member, is subjected to force from the electrode material in contact with it, causing the gap to expand, at least one of increasing the frequency and amplitude of the vibration of the film-forming member can reduce the viscosity and improve the fluidity of the electrode material, thereby quickly returning the tip of the film-forming material to its original position before the expansion. This can suppress changes in the thickness of the electrode material film caused by the expansion of the gap.

[0048] 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: A strain gauge is attached to the blade, which is the film-forming member, to detect the force from the electrode material (specifically, the normal stress from the electrode material). When it is detected that the gap has been expanded by the force 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 this information.

[0049] A more specific explanation will be given. The piezoelectric actuator is compressed and contracted by the force received from the electrode material. This causes the gap to be detected as being expanded. As the amount of 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, expanding the gap and resulting in an increase in the thickness of the electrode material film. Therefore, when a state in which the gap is being expanded is detected, it is desirable to apply strong energy to the electrode material in that region to suppress fluctuations in the thickness of the electrode material film. Specific means for this include: 1. increasing the overall length of the piezoelectric actuator to narrow the expanded gap; 2. increasing the number of times the film-forming material vibrates (i.e., increasing the frequency); and 3. increasing the vibration amplitude of the film-forming material. By using any of these means, fluctuations in the thickness of the electrode material film can be suppressed.

[0050] The force received from the electrode material, detected by a strain gauge attached to the deposition member, is converted into voltage by a dynamic strain gauge (amplifier). The converted voltage waveform is input into a computer such as a PC, which calculates the amplitude, frequency, and phase of the voltage waveform so that control is applied to the electrode material once per length of approximately 1 mm in the conveyance direction (i.e., MD). The calculated values ​​are transmitted to the PLC, which corrects the difference in vibration amplitude and frequency from the set values ​​to achieve the optimal value (set clearance) when contact is made with the electrode material.

[0051] In this manner, an electrode material film is formed on the current collecting foil placed on the conveying member.

[0052] [Step E] The manufacturing method of an electrode layer according to the present disclosure may include step E of separating the connected pallets and dividing the laminate of the current collecting foil and the electrode material film into individual pallets after step D. In step E, the long electrode material film formed in step D is cut together with the current collecting foil to the length of the pallet (specifically, the length in the conveying direction of the pallet (Z direction in FIG. 1 )).

[0053] In step E, the connected pallets are separated from each other, and the separation conditions may be determined appropriately depending on the ease with which the formed electrode material film crumbles. Examples of the separation conditions include the speed or acceleration when separating the pallets. The more easily the electrode material film crumbles, the lower the speed or acceleration when separating the pallets.

[0054] In this manner, an electrode layer, which is a laminate of current collecting foils and electrode material films (divided laminate 72 in FIG. 1), is formed on the pallet.

[0055] [Other Steps] The method for manufacturing an electrode layer according to the present disclosure may include other steps, such as a step of pressurizing the electrode material film.

[0056] (Step of Pressurizing Electrode Material Film) The method for manufacturing an electrode layer according to the present disclosure may include a step of pressurizing the electrode material film. By including the pressurizing step in the method for manufacturing an electrode layer according to the present disclosure, it is possible to increase the density of the electrode material and achieve in-plane uniformity in the density and thickness of the solid component.

[0057] In this step, it is preferable to pressurize the electrode material film by, for example, using a pressure roller to pressurize the laminate placed on a pallet. At this time, it is preferable that a film is placed on the electrode material film, and the laminate is pressed by pressing the pressure roller against the film. Note that in this step, for example, a press may be used as the pressurizing means. Furthermore, a vibrating pressurizing means may be used as the pressurizing means.

[0058] 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.

[0059] In this step, the laminate may be pressurized in stages using a plurality of pressurizing means. By pressurizing the electrode material film in stages using a plurality of pressurizing means, the density and thickness of the electrode material can be made more uniform.

[0060] This step is preferably performed by moving the pressure applying means and the electrode material film (specifically, the current collecting foil on which the electrode material film is formed) relative to each other. In the present disclosure, "moving the pressure applying means and the electrode material film relative to each other" includes moving the pressure applying means in one direction relative to the electrode material film, moving the electrode material film in one direction relative to the pressure applying means, and moving both the pressure applying means and the electrode material film in one direction, but it is preferable to move the electrode material film in one direction relative to the pressure applying means.

[0061] In this step, from the viewpoint of improving formability, the electrode material film may be heated at, for example, 30° C. to 100° C. and then pressurized.

[0062] Hereinafter, the current collecting foil and the molded member used in the manufacturing method of the electrode layer according to the present disclosure will be described in detail, along with the electrode material (materials including an electrode active material, a conductive additive, an electrolyte solution, etc.).

[0063] [Current Collector Foil] The current collector foil is not particularly limited, and known current collector foils (positive electrode current collector foil and negative electrode current collector foil) can be used.

[0064] Examples of the positive electrode current collector foil include aluminum, aluminum alloy, 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 be aluminum having a coating layer on its surface containing one or more of carbon, nickel, titanium, silver, gold, platinum, and vanadium oxide.

[0065] Examples of negative electrode current collector foils include aluminum, copper, copper alloys, stainless steel, nickel, and titanium. The negative electrode current collector foil is preferably aluminum, copper, a copper alloy, or stainless steel, and more preferably copper or a copper alloy. The negative electrode current collector foil may be copper or stainless steel having a coating layer on its surface containing one or more of carbon, nickel, titanium, silver, and lithium.

[0066] The current collector foil is preferably an aluminum foil (including an aluminum foil having the above-described coating layer on its surface) or a copper foil (including a copper foil having the above-described coating layer on its surface). Aluminum foil is usually used as a current collector foil for a positive electrode. Copper foil is usually used as a current collector foil for a negative electrode.

[0067] The current collector foil may be a laminate of a metal layer exemplified as the positive electrode current collector foil or the negative electrode current collector foil described above and a resin film. Examples of the resin film used in the laminate include polyethylene terephthalate (PET) film, polypropylene (PP) film, polyethylene (PE) film, cyclic olefin polymer (COP, COC) film, triacetyl cellulose (TAC) polyimide (PI) film, and polyamide (PA) film.

[0068] When using the above-described laminate of a metal layer and a resin film, it is preferable that the surface of the metal layer on which the electrode material film is formed be separable in the plane direction. For example, a current collector foil can be used by arranging multiple metal layers (metal layers that will become current collector foils) of desired sizes spaced apart from one another on a resin film, folding the resin film portions between the metal layers toward the side opposite the metal layer, and then seamlessly contacting the previously separated metal layers. In such a current collector foil, the seamlessly contacting metal layers can be separated by the spacing between the pallets.

[0069] The thickness of the current 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, from the viewpoint of transportability, etc. 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, from the viewpoint of flexibility and lightness. The thickness of the current collector foil is determined in the same manner as the thickness of the electrode material film.

[0070] [Shaping Member] The shaping member may be a blade. As described above, the blade as the shaping member may be vibrating when it comes into contact with the electrode material.

[0071] (Blade) The blade is a plate-shaped member, and the shape, size, material, etc. of the contact portion that comes into contact with the electrode material may be determined appropriately depending on the physical properties of the electrode material (e.g., the type of electrode active material, the concentration of solid components, the composition of the electrolyte (viscosity, surface tension), etc.), the size and thickness of the electrode material film to be formed, etc. Furthermore, it is preferable that the electrode material does not easily adhere to the contact portion of the blade with the electrode material. For example, it is preferable that at least the surface of the blade exhibits mold-releasability. For example, the blade may be made of a fluororesin such as polytetrafluoroethylene (PTFE) or a resin such as polyether ether ketone (PEEK), or may be made of a metal such as stainless steel, aluminum, iron, or cemented carbide, or may be made of ceramic. Furthermore, to impart mold-releasability to the surface, the blade may have a surface layer that exhibits mold-releasability (e.g., a surface layer containing a fluororesin, a surface layer containing silicon-based particles and a resin). Furthermore, in order to enhance wear resistance, the blade may have a high-hardness coating such as titanium oxide, titanium nitride (TiN), or tungsten carbide on the metal or ceramic blade body.

[0072] [Electrode Material] The electrode material contains an electrode active material, a conductive additive, and an electrolyte solution, and may contain additives as necessary. The solid component concentration of the electrode material is preferably 30% by volume to 90% by volume, and more preferably 40% by volume to 80% by volume.

[0073] (Electrode active material) The electrode active material is a material capable of inserting and releasing ions of a metal element belonging to Group 1 or Group 2 of the periodic table. The electrode active material is contained in a solid component. Examples of the electrode active material include a positive electrode active material and a negative electrode active material.

[0074] -Positive Electrode Active Material- The positive electrode active material is not limited, and any known electrode active material used for positive electrodes can be used. The positive electrode active material is preferably a positive electrode active material that can reversibly insert and release lithium ions.

[0075] Specific examples of the positive electrode active material include transition metal oxides and elements that can be composited with lithium (e.g., sulfur). Among the above, the positive electrode active material is preferably a transition metal oxide.

[0076] 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).

[0077] 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.

[0078] The transition metal oxide may also 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 element Ma.

[0079] Examples of transition metal oxides 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 halide phosphate compounds, and lithium-containing transition metal silicate compounds.

[0080] 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 (nickel cobalt lithium 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 O ２ (lithium manganese nickel oxide).

[0081] 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 , and Li ２ NiMn ３ O ８ Examples include:

[0082] Examples of lithium-containing transition metal phosphate compounds include olivine-type iron phosphate salts (e.g., LiFePO ４ , and Li ３ Fe ２ (P.O. ４ ) ３ ), iron pyrophosphate (e.g., LiFeP ２ O ７ ), cobalt phosphate salts (e.g., LiCoPO ４ ), monoclinic Nasicon-type vanadium phosphate salts (e.g., Li ３ V ２ (P.O. ４ ) ３ (Lithium vanadium phosphate)).

[0083] Examples of lithium-containing transition metal halophosphate compounds include iron fluorophosphates (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).

[0084] Examples of lithium-containing transition metal silicate compounds include Li ２FeSiO ４ , Li ２ MnSiO ４ , and Li ２ CoSiO ４ Examples include:

[0085] The transition metal oxide is preferably a transition metal oxide having a layered rock salt structure, such as LiCoO ２ (Lithium cobalt oxide [LCO]), LiNi ０．８５ Co ０．１０ Al ０．０５ O ２ (nickel cobalt lithium aluminum oxide [NCA]), and LiNi １／３ Co １／３ Mn １／３ O ２ (nickel manganese cobalt oxide [NMC]) and more preferably at least one compound selected from the group consisting of:

[0086] The positive electrode active material may be a commercially available product or a synthetic product produced by a known method (e.g., a calcination method). For example, the positive electrode active material obtained by the calcination method may be washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent. The positive electrode active material may also have a carbon coating on its surface.

[0087] The shape of the positive electrode active material is not limited, but from the viewpoint of ease of handling, it is preferably in the form of particles.

[0088] 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. When the volume average particle size of the positive electrode active material is 0.3 μm or more, scattering of the positive electrode active material during handling can be suppressed. When the volume average particle size of the positive electrode active material is 40 μm or less, the thickness of the electrode layer can be easily adjusted and the occurrence of voids during the molding process can be suppressed.

[0089] The volume average particle size of the positive electrode active material is measured by the following method. A dispersion containing 0.1 mass % or less of the 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 is irradiated with 1 kHz ultrasound for 10 minutes and used as a measurement sample. Using a laser diffraction / scattering particle size distribution measurement device (e.g., LA-960 manufactured by Horiba, Ltd.), data is acquired 50 times at a temperature of 25°C, and the volume average particle size is determined from the volume frequency particle size distribution. A quartz cell is used as the measurement cell. The above measurement is performed using five samples, and the average of the measured values ​​is used as the volume average particle size of the positive electrode active material. For other detailed conditions, refer to "JIS Z 8828:2013" as necessary.

[0090] Examples of methods for adjusting the particle size of the positive electrode active material include methods using a pulverizer, a crusher, or a classifier. Alternatively, known milling methods may be used to adjust the particle size of the positive electrode active material.

[0091] The positive electrode active material may be used alone or in combination of two or more. Even when one type of positive electrode active material is used, positive electrode active materials having different particle sizes may be used in combination.

[0092] 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. In the method for producing an electrode layer according to the present disclosure, the amount of the positive electrode active material used is determined so that the content in the electrode material film falls within the above-mentioned range.

[0093] -Negative electrode active material- The negative electrode active material is not limited, and any known electrode active material used for negative electrodes can be used. The negative electrode active material is preferably a negative electrode active material that can reversibly insert and release lithium ions.

[0094] Examples of the negative electrode active material include carbonaceous materials, metal oxides (e.g., tin oxide), silicon oxide, metal composite oxides, lithium alone, lithium alloys (e.g., lithium-aluminum alloys), and metals capable of forming alloys with lithium (e.g., Sn, Si, and In). Among these, the negative electrode active material is preferably a carbonaceous material or a lithium composite oxide from the viewpoint of reliability.

[0095] Carbonaceous materials are materials consisting essentially of carbon. 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 tabular graphite. In this disclosure, "tabular" refers to a shape having two major planes facing in opposite directions.

[0096] The metal composite oxide is preferably a metal composite oxide capable of absorbing and desorbing lithium. From the viewpoint of high current density charge / discharge characteristics, the metal composite oxide capable of absorbing and desorbing lithium preferably contains at least one element selected from the group consisting of titanium and lithium.

[0097] The metal oxide and metal composite oxide are particularly preferably amorphous oxides.

[0098] The metal oxides and metal composite oxides are also preferably chalcogenides, which are reaction products of metal elements and elements of Group 16 of the periodic table.

[0099] Among the compound group consisting of amorphous oxides and chalcogenides, amorphous oxides and chalcogenides of metalloid elements are preferred, and oxides and chalcogenides containing at least one element selected from the group consisting of elements of Groups 13 to 15 in the periodic table, Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi are more preferred.

[0100] It is also preferable that the negative electrode active material further contains titanium. From the viewpoint that the volume change during the absorption and desorption of lithium ions is small, and thus rapid charge and discharge characteristics are excellent, and that deterioration of the electrode is suppressed, thereby enabling an improvement in the life of the lithium ion secondary battery, the negative electrode active material containing titanium is preferably Li ４ Ti ５ O １２ (lithium titanate [LTO]) is preferred.

[0101] The negative electrode active material may be a commercially available product or a synthetic product produced by a known method (e.g., a calcination method). For example, the negative electrode active material obtained by the calcination method may be washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

[0102] The negative electrode active material is available, for example, as CGB20 (Nippon Graphite Industries Co., Ltd.).

[0103] The composition of the negative electrode active material is measured using inductively coupled plasma (ICP) emission spectroscopy.

[0104] The shape of the negative electrode active material is not limited, but is preferably particulate from the viewpoints of ease of handling and ease of control of uniformity during mass production.

[0105] 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. The volume average particle size of the negative electrode active material is measured by a method similar to the method for measuring the volume average particle size of the positive electrode active material.

[0106] The particle size of the negative electrode active material can be adjusted, for example, by using a pulverizer or a classifier.

[0107] The negative electrode active material may be used alone or in combination of two or more. Even when one type of negative electrode active material is used, negative electrode active materials having different particle sizes may be used in combination.

[0108] 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. In the method for producing an electrode layer according to the present disclosure, the amount of the negative electrode active material used is determined so that the content in the electrode material film falls within the above-mentioned range.

[0109] The surfaces of the positive electrode active material and the negative electrode active material may each be coated with a surface coating agent. Examples of the surface coating agent include metal oxides containing Ti, Nb, Ta, W, Zr, Si, or Li. Examples of the metal oxide include titanate spinel, tantalum-based oxides, niobium-based oxides, and lithium niobate-based compounds.

[0110] (Conductive additive) The electrode material film contains a conductive additive from the viewpoint of improving the electronic conductivity of the electrode active material. There are no limitations on the conductive additive, and known conductive additives can be used. The conductive additive is contained in the solid component.

[0111] Examples of conductive additives include graphite (e.g., natural graphite and artificial graphite), carbon black (e.g., acetylene black, ketjen black, and furnace black), amorphous carbon (e.g., needle coke), carbon fibers (e.g., vapor-grown carbon fibers and carbon nanotubes), other carbonaceous materials (e.g., graphene and fullerene), metal powders (e.g., copper powder and nickel powder), metal fibers (e.g., copper fibers and nickel fibers), and conductive polymers (e.g., polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives).

[0112] The conductive additive may be used alone or in combination of two or more kinds.

[0113] The content of the conductive additive relative to the total volume of the electrode material is preferably 0.05% by volume to 5% by volume, more preferably 0.1% by volume to 4% by volume, and even more preferably 0.5% by volume to 3% by volume. In the method for producing an electrode layer according to the present disclosure, the amount of the conductive additive used is determined so that the content in the electrode material film falls within the above-mentioned range.

[0114] (Electrolyte) The electrolyte is not particularly limited, and a known electrolyte can be used. For example, the electrolyte contains an electrolyte and a solvent. For example, a specific electrolyte contains a lithium salt compound as the electrolyte and a carbonate compound as the solvent.

[0115] An example of the lithium salt compound is lithium hexafluorophosphate. The electrolyte solution may contain one kind of lithium salt compound alone, or may contain two or more kinds of lithium salt compounds.

[0116] Examples of carbonate compounds include linear carbonate compounds such as ethyl methyl carbonate (also referred to as EMC), dimethyl carbonate (also referred to as DMC), and diethyl carbonate (DEC), and cyclic carbonate compounds such as ethylene carbonate (also referred to as EC) and propylene carbonate (also referred to as PC). The electrolyte may contain one type of carbonate compound alone, or may contain two or more types of carbonate compounds, or may use one or more linear carbonate compounds and one or more cyclic carbonate compounds in combination.

[0117] As the electrolyte contained in the electrolytic solution, for example, a known inorganic solid electrolyte can be used.

[0118] An ionic liquid may be used as a component of the electrolytic solution, for example. The ionic liquid may be used as either an electrolyte or a solvent.

[0119] The content of the electrolyte solution relative to the total volume of the electrode material is preferably 70% by volume or less, and may be 50% by volume or less, or 40% by volume or less. The lower limit of the content of the electrolyte solution relative to the total volume of the electrode material is not limited, and may be 10% by volume or more, or 30% by volume or more. 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.

[0120] (Solvent) The electrode material film may contain, as a liquid component, a solvent (hereinafter simply referred to as "solvent") other than the solvent contained as a component of the electrolyte solution. 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.

[0121] The boiling point of the solvent at normal pressure (i.e., 1 atmosphere) is preferably 50° C. or higher, and more preferably 70° C. or higher. The upper limit of the boiling point of the solvent at normal pressure (i.e., 1 atmosphere) is preferably 250° C. or lower, and more preferably 220° C. or lower.

[0122] The solvents may be used alone or in combination of two or more.

[0123] The content of the liquid components (i.e., the 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, or 40% by volume or less. The lower limit of the content of the liquid components relative to the total volume of the electrode material is not limited, and may be 10% by volume or more, or 30% by volume or more. The content of the liquid components relative to the total volume of the electrode material is preferably 30% by volume to 50% by volume.

[0124] Note that the liquid components contained in the electrode material film, i.e., the components in the electrode material film that are liquid at 25° C., are preferably liquid even at −10° C., and are preferably liquid even at −20° C. In other words, the components in the electrode material film that are liquid at 25° C. are preferably components that do not solidify even at −10° C., and are preferably components that do not solidify even at −20° C.

[0125] (Other Components) In addition to the above-mentioned components, the electrode material film may contain binders, dispersants, other additives, etc. However, from the viewpoint of improving the energy density, it is preferable that the electrode material film has a low binder content, and it is more preferable that the electrode material film does not contain any binder. Examples of binders include fluorine-containing resins, hydrocarbon-based thermoplastic resins, acrylic resins, and urethane resins. Furthermore, the dispersant may be any known dispersant that can disperse the substance to be dispersed. Furthermore, known additives that are added to electrodes can be used as other additives.

[0126] <<Electrode Layer>> The electrode layer obtained by the electrode layer manufacturing method according to the present disclosure can be used as various electrodes. The sheet electrode layer may be used as an electrode as is, or may be further processed to form an electrode. The sheet electrode layer is preferably an electrode layer for a semi-solid secondary battery.

[0127] From the viewpoint of improving battery performance (e.g., discharge capacity and output characteristics), the electrode layer preferably has a thickness of 50 μm to 500 μm and a solid component concentration of 30% by volume to 90% by volume, similar to the above-mentioned electrode material film. The thickness and solid component concentration of the electrode layer are determined by the same method as the thickness and solid component concentration of the electrode material film.

[0128] Furthermore, when a positive electrode layer and a negative electrode layer are manufactured by the electrode layer manufacturing method according to the present disclosure, a battery can be obtained by bonding the obtained positive electrode layer and negative electrode layer together via a separator.

[0129] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited thereto. Note that each step in each example described below was carried out in a dry room (low dew point room) at 22°C.

[0130] [Preparation of Positive Electrode Material (P1)] (1) 45 g of ethylene carbonate (EC), 10 g of propylene carbonate (PC), and 45 g of diethyl carbonate (DEC) were mixed, and LiPF ６After mixing 13.4 g of the electrolyte, 2.3 g of vinylene carbonate (VC) was further mixed. Of the resulting 115.7 g of mixed solution, 64 g was removed and designated as electrolyte solution X1. (2) 2 g of a conductive additive (Ketjen Black: "Carbon ECP600JD" manufactured by Lion Specialty Chemicals) and 174 g of a positive electrode active material (iron phosphate: "LFP NCO M121" manufactured by Aleees) were stirred in a mixer (manufactured by Thinky Corporation) at 1500 rpm (revolutions per minute) for 30 seconds to prepare kneaded material Y1 (176 g). (3) Electrolyte solution X1 (64 g) was added to kneaded material Y1 (176 g), and the mixture was stirred at 1,500 rpm for 120 seconds using a mixer (Thinky Corporation) to obtain a positive electrode material (P1). The obtained positive electrode material (P1) was a Bingham fluid with a yield value of 45 kPa and a volume ratio of solid component to liquid component of 48:52.

[0131] [Preparation of Current Collector Foil (S1)] Current collector foil (S1): A positive electrode current collector foil (aluminum foil, average thickness 20 μm, Ra 0.5 μm, EAA-218D, carbon-coated product manufactured by JCC Korea) to which a heat-sealing layer of a PET film having a heat-sealing layer containing ethylene-vinyl acetate copolymer (EVA) was attached by heat fusion to the back surface. Note that the Ra of the current collector refers to the arithmetic mean roughness Ra of the surface on which the electrode material film is formed.

[0132] [Preparation of Blade (B1)] Blade (B1): Stainless steel blade

[0133] [Preparation of Pallet (P1)] Pallet (P1): A pallet made of 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 measuring 500 mm (width direction) x 150 mm (transport direction). There are grooves in some parts for air supply.

[0134] Example 1 An electrode material film was formed on a current collector foil using an apparatus such as that shown in FIG. 1 . In Example 1, a current collector foil (S1) and a positive electrode material (P1) were used. Pallet (P1) and blade (B1) were used as the pallet 10 and blade 60, respectively. First, the surface shape of each of the multiple pallets 10 to which the current collector foils were fixed was measured using a non-contact laser interferometer. After measuring the surface shape, blade 60 was positioned so as to maintain a fixed distance of 200 μm from the surface of current collector foil 30 placed on conveying member 12 to which pallets 10 were connected. Based on this set position, the position of the tip of blade 60 was set relative to the measured surface shape of pallet 10. Here, the position of the tip of blade 60 was adjusted using only the expansion and contraction of ball screw 64. In other words, the position of the tip of blade 60 was adjusted to follow the surface shape of pallet 10 using the expansion and contraction of ball screw 64. The electrode material 40 was supplied onto the current collector foil 30 using an electrode material supply device 50, forming a reservoir 46 of the electrode material 40 between the current collector foil 30 and the blade 60. The conveying member 12 was then moved in the Z direction (i.e., the MD direction) to regulate the thickness of the electrode material 40 with the shaping member, forming an electrode material film 42 on the current collector foil 30. The movement speed of the conveying member 12, i.e., the conveying speed of the current collector foil, was 10 mm / sec. The blade, which served as the shaping member, was vibrated by a piezoelectric actuator. The amplitude of the vibrating blade was ±3 μm and the frequency was 600 Hz. Next, the pallets 10 were separated at a speed of 10 mm / sec, and the laminate 70 of the current collector foil 30 and the electrode material film 42 was divided into individual pallets. The solids concentration of the resulting electrode material film was 47% by volume. In this manner, an electrode layer was obtained.

[0135] Example 2 An electrode layer was obtained in the same manner as in Example 1, except that the position of the tip of the blade 60 was set as follows. That is, the position of the tip of the blade 60 was adjusted using 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, the position of the tip of the blade 60 was adjusted so as to follow the surface shape of the pallet 10 using the expansion and contraction of the ball screw 64 as well as the expansion and contraction of the piezoelectric element in the piezoelectric actuator 62. The solids concentration of the electrode material film obtained in this example was 47% by volume.

[0136] Example 3 An electrode layer was obtained in the same manner as in Example 2, except that the moving speed of the conveying member 12 when forming the electrode material film 42, i.e., the conveying speed of the current collecting foil, was changed to 200 mm / sec. The solid content concentration of the electrode material film obtained in this example was 47% by volume.

[0137] Example 4 An electrode layer was obtained in the same manner as in Example 2, except that the movement speed of the conveying member 12 during the formation of the electrode material film 42, i.e., the conveying speed of the current collector foil, was changed to 200 mm / sec, and the position of the tip of the blade 60 was set as follows. The setting of the position of the tip of the blade 60 is described in detail below. The length of the pallet in the conveying direction was defined as a reference length L, and the numerical values ​​of the surface shape of one pallet were Fourier transformed to calculate the amplitudes for each of the reference lengths L, L / 2, L / 3, L / 4, .... Based on the calculated values, the amplitude amount of the L period (first-order component) for the position of the tip of the blade 60 was adjusted by expanding and contracting the ball screw 64, and further, the amplitude amount of the L / 4 period (fourth-order component) was adjusted by expanding and contracting the piezoelectric element. The solids concentration of the electrode material film obtained in this example was 47% by volume.

[0138] <Evaluation of in-plane thickness uniformity> After forming the electrode material film, the surface shape of the electrode material film was measured in the same manner as the surface shape of the current collector foil surface. The obtained measured values ​​of the surface shape of the electrode material film and the measured values ​​of the surface shape of the current collector foil surface could be correlated with the position information of the pallet, and the difference at each position was taken as the thickness of the electrode material film. The thickness was extracted at 100 points every 1 mm along the conveyance direction. The measurement positions were one line at the center of the electrode material film in the width direction and two lines spaced 90 mm to the left and right from the center, for a total of three lines. Based on the thickness values ​​for 300 points x 3 lines, the average value and standard deviation (average value ± standard deviation) were calculated. The results are shown below. Example 1: 210 μm ± 13 μm Example 2: 203 μm ± 3 μm Example 3: 201 μm ± 6 μm Example 4: 202 μm ± 4 μm

[0139] (Explanation of symbols) 10: Pallet 12: Conveying member 20: Surface shape inspection device 30: Current collecting foil 32: Divided current collecting foil 40: Electrode material 42: Electrode material film 44: Divided electrode material film 46: Electrode material reservoir 50: Electrode material supply device 60: Film forming member (blade) 62: Piezoelectric actuator 64: Ball screw 66: Connection portion 70: Laminated body 72: Divided laminated body 80: Table 82: Rail 80: Table 82: Rail 84: Fixing member 90: LM guide Z: Conveying direction of conveying member A: Direction of force applied from electrode material to blade B: Direction in which piezoelectric actuator is extended

[0140] The disclosure of Japanese Patent Application No. 2022-159830, filed on October 3, 2022, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A method for manufacturing an electrode layer, comprising: step A of measuring the surface shape of a conveying member; step B of placing a current collecting foil on the conveying member after measuring the surface shape and conveying the current collecting foil by moving the conveying member; step C of supplying an electrode material containing an electrode active material, a conductive additive, and an electrolyte onto the conveyed current collecting foil; and step D of passing the electrode material supplied onto the current collecting foil through a gap formed between the conveying member and the tip of a film forming member positioned at a distance from the surface of the conveying member, thereby regulating the thickness of the electrode material to form an electrode material film, wherein in step D, the position of the film forming member is controlled based on the measurement information of the surface shape of the conveying 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 exerted by the electrode material on the film-forming member.

3. A method for manufacturing an electrode layer according to claim 1 or claim 2, wherein a vibrating film-forming member is used as the film-forming material, and 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 exerted by the electrode material on the film-forming member.

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

5. A method for manufacturing an electrode layer according to claim 1 or claim 2, wherein when X is the maximum height of the electrode material supplied in step C and Y is the width of the gap formed between the conveying member and the tip of a film-forming member arranged at a position spaced apart from the surface of the conveying member, the relationship X>Y is satisfied.