Method for manufacturing laminate of material layers, method for manufacturing electrode of solid battery, material layer, and method for manufacturing material layer

Abstract

Provided is a method for manufacturing a laminate with which the ratio of a base material to the total volume of the laminate is reduced. This method for manufacturing a laminate of material layers comprises: a step for arranging a plurality of particles on an adhesion surface of a first base material having the adhesion surface; a step for filling a binder, which is peelable from the adhesion surface, between the plurality of particles arranged on the adhesion surface so as to obtain a material layer which is an integrated object of the particles and the binder; and a step for peeling the material layer from the adhesion surface and laminating a plurality of the material layers so as to obtain a laminate of the material layers.

Description

Method for manufacturing laminate of material layers and method for manufacturing electrode of solid-state battery, material layer, and method for manufacturing material layer

[0001] The present disclosure relates to a method for manufacturing a material layer and an electrode for a solid-state battery, and a material layer.

[0002] While various new manufacturing methods using additive manufacturing have been developed in recent years, the difficulty of designing and arranging multiple material particles to create functional structures has remained limited. For example, while the technique of arranging toner particles using electrophotography is widespread, toner particles are composed of composite materials that already contain binders in amounts many times greater than the amount of pigment used as the functional material to achieve electrostatic charging. Furthermore, due to the properties of static electricity, positioning individual particles is fundamentally difficult—a phenomenon that also applies to electrostatic screen printing, which allows for binderless particle patterning. By placing functional particles in the right places, unnecessary particles can be avoided, resulting in greater benefits, especially for expensive materials such as battery materials.

[0003] Conventionally, Patent Document 1 discloses a technology for manufacturing a solid-state battery in which particles arranged on a substrate are stacked together with the substrate in multiple layers to obtain a laminate, thereby manufacturing a solid-state battery with a larger capacity.

[0004] Japanese Patent Application Laid-Open No. 2019-137060

[0005] The substrate in the laminate produced by the method of Patent Document 1 is removed because it contributes little to the characteristics of the solid-state battery. Therefore, it is desirable that the ratio of the substrate to the total volume of the laminate be small. However, because the substrate also serves as a support for the particles, it has been difficult to make the substrate thinner than a certain level.

[0006] The present disclosure provides a method for manufacturing a laminate in which the proportion of the substrate in the total volume of the laminate is smaller. The present disclosure also provides a method for manufacturing an electrode for a solid-state battery using the laminate. The present disclosure also provides a material layer in which the proportion of the substrate is smaller. The present disclosure also provides a method for manufacturing a material layer in which the proportion of the substrate is smaller.

[0007] The present disclosure relates to a method for manufacturing a laminate of material layers, the method comprising the steps of: arranging a plurality of particles on an attachment surface of a first substrate having the attachment surface; filling a binder that can be peeled off from the attachment surface between the plurality of particles arranged on the attachment surface to obtain a material layer that is an integral body of the particles and the binder; and peeling the material layer from the attachment surface and stacking the plurality of material layers to obtain a laminate of the material layers.

[0008] The present disclosure also relates to a method for manufacturing an electrode for a solid-state battery, the method including a step of heating and degreasing the laminate obtained by the method for manufacturing a laminate of material layers to remove the binder, thereby obtaining the electrode.

[0009] The present disclosure also relates to a material layer that is an integral body of a plurality of particles and a binder, wherein the binder is filled between the plurality of particles, and at least a portion of the plurality of particles is exposed from the binder on at least one surface of the material layer, and when the material layer is observed from the side where at least a portion of the plurality of particles is exposed, the ratio of the total area of ​​the exposed portions of the particles to the area of ​​a particle arrangement area where the plurality of particles are present is 1 to 70 area %.

[0010] The present disclosure also relates to a method for manufacturing a material layer, the method comprising the steps of: arranging a plurality of particles on an attachment surface of a first substrate having the attachment surface; filling a binder that is peelable from the attachment surface between the plurality of particles arranged on the attachment surface to obtain a material layer that is an integral body of the particles and the binder; and peeling the material layer from the attachment surface.

[0011] According to the present disclosure, there is provided a method for manufacturing a laminate in which the proportion of the substrate in the total volume of the laminate is smaller. Also according to the present disclosure, there is provided a method for manufacturing an electrode for a solid-state battery using the laminate. Also according to the present disclosure, there is provided a material layer in which the proportion of the substrate is smaller. Also according to the present disclosure, there is provided a method for manufacturing a material layer in which the proportion of the substrate is smaller.

[0012] FIG. 1 is an image diagram showing a method for manufacturing a material layer. FIGS. 2A, 2B, 2C, 2D, 2E, 2F, and 2G are explanatory diagrams illustrating a manufacturing process of a stack of material layers. FIG. 3 is a schematic diagram of an apparatus for manufacturing a stack of material layers. FIG. 4 is an explanatory diagram of an air knife coater. FIGS. 5A, 5B, 5C, and 5D are explanatory diagrams of a stack. FIGS. 6A and 6B are schematic diagrams of material layers. FIG. 7 is an explanatory diagram of a secondary electron image of a material layer.

[0013] In the present disclosure, expressions such as "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints, unless otherwise specified. Furthermore, when a numerical range is described in stages, the upper and lower limits of each numerical range can be combined in any way. Furthermore, in the present disclosure, expressions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ. Note that when XX is a group, multiple XXs may be selected, and the same applies to YY and ZZ.

[0014] In the present disclosure, a layer of material particles is formed on a first substrate as an intermediate transfer member, and then a binder that will become the final substrate is infiltrated between the particles to obtain a material layer that is an integrated particle-binder structure. The material layers are then stacked to obtain a laminate, thereby reducing the amount of binder (substrate amount), which is an unnecessary component in the target laminate. Therefore, when removing the substrate, removal is facilitated. For example, when removing the substrate by heating, the heating temperature can be lowered and the heating time can be shortened.

[0015] It is also possible to form a pattern using material particles, in which case the accuracy of the pattern can be maintained by holding the particles on an intermediate transfer body until a unit of the particles containing the pattern and the binder is obtained.

[0016] Specifically, for example, particles are temporarily fixed as a pattern on a weakly adhesive surface with elastic deformation, such as silicone rubber, without using a fixing material. Then, a treatment liquid containing a binder is allowed to penetrate into the gaps in the particle pattern, and after removing the solvent, the particles are transferred to the transfer target and laminated. This method allows the particles to be fixed with a small amount of binder depending on the particle size used, and also allows the use of a binder material that is easy to remove.

[0017] An embodiment of the present disclosure will be illustrated below step by step. Fig. 1 is a flowchart of a method for manufacturing a particle-containing material layer. Fig. 2 shows a specific example of a manufacturing process for a stack of material layers in the order of steps.

[0018] A method for manufacturing a laminate of material layers includes the steps of: arranging a plurality of particles on an attachment surface of a first substrate having the attachment surface; filling a binder that can be peeled off from the attachment surface between the plurality of particles arranged on the attachment surface to obtain a material layer that is an integral body of the particles and the binder; and peeling the material layer from the attachment surface and stacking the plurality of material layers to obtain a laminate of the material layers.

[0019] The particles are preferably patterned. There are no limitations on the method for forming a particle pattern on the attachment surface. Since the particles are held together by the adhesive force at the interface between the attachment surface serving as an intermediate transfer member and the particles, the particles are basically held together at a thickness equivalent to a single layer of particles regardless of the patterning method used. The method can be suitably selected depending on the particles used, whether it is a plate-based method such as relief printing or intaglio printing, or a plateless method such as electrophotography. Among these, a patterning method using a mask is preferred.

[0020] Below, an example of arranging first particles and second particles using a mask will be described, but the multiple particles are not limited to this form. The multiple particles may be of one type of particle. Here, the type may be, for example, a type of compound. For example, the multiple particles may include multiple particles of the same compound. Furthermore, the multiple particles may include a first particle, a second particle, a third particle, ..., an nth particle. For example, multiple particles can be arranged by using multiple masks.

[0021] The process of arranging a plurality of particles on the adhesion surface preferably includes a first process of forming a mask on the adhesion surface, a second process of arranging first particles in the non-masked areas of the adhesion surface, a third process of removing the mask from the adhesion surface, and a fourth process of arranging second particles in the non-arranged areas of the first particles remaining on the adhesion surface.

[0022] Alternatively, the plurality of particles may be arranged without using a mask. For example, the step of arranging the plurality of particles on the attachment surface may be a step of arranging the first particles on the attachment surface.

[0023] 2A to 2G show a specific example of the process of the present disclosure in the order of steps. First, a first substrate 20 (intermediate transfer member) having a particle-carrying layer 29 that forms an attachment surface 21 on the surface of a support 101 is prepared ( FIG. 2A ). A mask 22 having openings 23 is formed on the attachment surface 21 of the first substrate 20 ( FIG. 2B ). There are no particular restrictions on the formation of the mask 22, and known means can be used. For example, a mask layer may be formed separately on a support member, patterned to obtain the desired openings 23, and then the mask 22 may be transferred from the support member to the attachment surface 21.

[0024] Then, first particles 24 are placed in the openings 23 on the attachment surface 21, which are the portions where the mask 22 is not formed (FIG. 2C). This allows the first particles 24 to adhere to the attachment surface 21. Next, the mask 22 is removed from the attachment surface 21 (FIG. 2D). By removing the mask, new portions where the first particles are not placed are exposed on the attachment surface. Second particles 25 are placed in the exposed portions where the first particles are not placed (FIG. 2E). This allows the second particles 25 to adhere to the attachment surface 21, completing the pattern of the first particles and the second particles.

[0025] A binder 27 that can be peeled from the attachment surface is filled between the particles in this pattern of first and second particles to obtain a material layer that is an integral combination of the particles and the binder. For example, a binder solution containing the binder is infiltrated between the particles, and then dried to obtain a material layer that is an integral combination of the particles and the binder (FIG. 2F). The obtained material layer can then be peeled from the attachment surface 21 (FIG. 2G). The obtained material layers can be stacked to obtain a laminate (FIG. 5A).

[0026] 3 shows an example of an apparatus 100 for producing a material layer and a material layer stack according to one embodiment of the present disclosure. The apparatus is, for example, an apparatus for producing a positive electrode material layer and further a positive electrode material layer stack.

[0027] Using the apparatus shown in FIG. 3 , for example, a PET film mask with openings formed by a UV laser 6 is attached to an intermediate transfer body 1 having a silicone rubber surface. Then, particles of a battery cathode material are supplied by a first particle supply unit 7, and after the mask is peeled off, particles of a battery solid electrolyte are supplied by a second particle supply unit 11. Furthermore, a treatment liquid containing an acrylic binder is supplied to gaps between the particle layers on the intermediate transfer body 1 by an air knife coater 13, allowed to penetrate, and then the solvent is removed to produce a cathode material layer. These material layers are then laminated in a lamination device 15 to produce a laminate of cathode material layers. The production apparatus 100 will now be described.

[0028] The manufacturing apparatus 100 is equipped with a belt-like intermediate transfer body 1, a transport device that transports the intermediate transfer body 1 between processes, and processing means for performing the processes shown in Fig. 2. The intermediate transfer body 1 is the first substrate 20 having the above-mentioned attachment surface 21.

[0029] The manufacturing apparatus 100 is centered around a transport device 2 that drives an intermediate transfer body 1, and includes a mask layer attachment unit including a mask layer supply section 30 that supplies a mask layer 3 and a pressure roller 4, a mask manufacturing unit 6 (UV laser 6), a cleaning roller 5, a first particle supply unit 7, and an air blower 8. The manufacturing apparatus 100 also includes a mask removal unit that is composed of a peeling roller 9 and a winding device 10. The manufacturing apparatus 100 also includes a second particle supply unit 11 and an air blower 12.

[0030] The manufacturing apparatus 100 also includes an air knife coater 13 as a means for applying a treatment liquid containing a binder to fill the particles with the binder, and a solvent removal promoting means 14 for removing the solvent after the treatment liquid has been applied. The manufacturing apparatus 100 also includes a lamination device 15 for laminating material layers, in which the binder is heated by a heater 16 to laminate the material layers, and the binder is cooled by a cooling fan 17 to make it easier to peel the material layers from the intermediate transfer body.

[0031] A material layer is manufactured by sequentially performing processing in these units. Although the apparatus shown in Figure 3 is configured to perform each step in a series, the present invention is not limited to this configuration and each step may be divided as appropriate. The following explanation will be given using the apparatus shown in Figure 3 as an example.

[0032] First, the intermediate transfer body needs to have the property of being able to transfer target particles to the final substrate while retaining them on its surface. To achieve this, the intermediate transfer body 1 has an attachment surface 21. The outer surface of the intermediate transfer body 1 serves as the attachment surface 21. For example, the intermediate transfer body 1 has a particle-carrying layer 29 having the attachment surface 21. That is, it is preferable that the first substrate has a support 101 and a particle-carrying layer 29 laminated on the support 101 to form the attachment surface 21.

[0033] The intermediate transfer body 1, which is the first substrate, temporarily holds the particles and ultimately releases them (i.e., transfers them to the desired transfer target), so the particle-carrying layer needs to have the property of being able to release the particles. A suitable property is, for example, that the particle-carrying layer 29 is an elastically deformable layer. If the particle-carrying layer 29 is rigid, the contact points with the particles tend to be small-area point contacts, which requires a strong adhesive force, which can result in incomplete particle release or damage to the particles or parts of the surface of the intermediate transfer body.

[0034] In this regard, if the particle-carrying layer 29 is elastically deformable, some of the particle contact points will sink into the transfer body, increasing the contact area and allowing the particles to be reliably held with weak adhesive force, allowing the material layer to be stably peeled off. If the adhesive layer is made of a plastically deformable material, the particles will be held in a buried state, making peeling difficult. The amount of particle sinking can be controlled by the rubber hardness of the surface of the intermediate transfer body.

[0035] Furthermore, as another characteristic that stabilizes peeling (transferability) from the intermediate transfer body, it is desirable that the adhesion surface 21 have low compatibility (adhesion and solubility) with the treatment liquid containing a binder. Therefore, the particle support layer 29 having the adhesion surface 21 should be selected based on its compatibility with the treatment liquid, particularly the solvent of the treatment liquid. As a specific material for the particle support layer 29 that satisfies these requirements, urethane rubber is preferred for aqueous treatment liquids. Furthermore, fluororubber and silicone rubber can be used with a wide range of materials, regardless of whether they are aqueous or solvent-based. Silicone rubber is particularly suitable because it has a wide range of adjustable adhesiveness and rubber hardness. The particle support layer 29 does not need to be made of a single rubber; multiple types can be used in combination depending on the properties.

[0036] For example, the adhesive force of the attachment surface 21 measured using a peel analysis device is preferably 0.2 to 10 mN / 20 mm, more preferably 0.4 to 5 mN / 20 mm, even more preferably 0.5 to 5 mN / 20 mm, and even more preferably 0.5 to 2 mN / 20 mm. The adhesive force was measured using a VPA-3 manufactured by Kyowa Interface Science Co., Ltd. under the following measurement conditions. In the examples described below, the sample size was 20 mm wide and 150 mm long. Measurement conditions: peel angle 90°, measurement temperature 25°C, peel rate 300 mm / min, target substrate: PET film. From the viewpoint of adequately retaining the particles, the adhesive force is preferably 0.2 mN / 20 mm or more. Furthermore, from the viewpoint of better transferability, the adhesive force is preferably 10 mN / 20 mm or less.

[0037] As for elastic properties, the rubber hardness of the adhesion surface 21 measured in accordance with JIS K6253-3:2012 is preferably 10° to 80° (JIS Type A), more preferably 15° to 40°, even more preferably 18° to 40°, and even more preferably 18° to 30°. Note that the rubber hardness in this disclosure refers to the durometer hardness that can be measured in accordance with JIS K6253-3:2012. The thickness of the particle support layer 29 is preferably, for example, 10 to 200 μm, or 40 to 120 μm.

[0038] Specifically, the material of the particle support layer 29 forming the adhesion surface 21 preferably includes silicone rubber, urethane rubber, or fluororubber. It may also be a mixture of any of these with other materials. The particle support layer 29, for example, includes at least one selected from the group consisting of silicone rubber, urethane rubber, and fluororubber, more preferably silicone rubber, and even more preferably silicone rubber. The particle support layer 29 preferably includes 10 to 100% by mass, more preferably 50 to 100% by mass, and even more preferably 80 to 100% by mass of at least one selected from the group consisting of silicone rubber, urethane rubber, and fluororubber. The particle support layer 29 preferably includes 10 to 100% by mass, more preferably 50 to 100% by mass, and even more preferably 80 to 100% by mass of silicone rubber.

[0039] The solubility of the particle-carrying layer that forms the adhesive surface with the binder liquid preferably satisfies the following: When the particle-carrying layer is immersed in the binder liquid for 1 hour in an environment of 25°C, the reduction rate of the particle-carrying layer is preferably 0 to 5% by mass, and more preferably 0 to 1% by mass. The above temperature simulates the process temperature. Satisfying the above mass reduction rate indicates that the binder liquid and the adhesive surface have low compatibility, which tends to result in better transferability.

[0040] In the device 100 of FIG. 3 , the intermediate transfer body 1 is in the form of a belt, but is not limited to this. For example, the intermediate transfer body 1 may be in the form of a roller or a flat plate. The support of the intermediate transfer body 1 is not limited, and commercially available materials can be used depending on the application. Examples include plastics such as polyamide resin, polyimide resin, polyacetal resin, and polyester resin; metals such as aluminum, stainless steel (SUS), and Invar alloy; and, if the support is in the form of a roll or a flat plate, glass, ceramics, and the like.

[0041] Since the particle-carrying layer 29 is easily stretched and contracted when used alone, and dimensional accuracy may be unstable, it is preferable to use a rigid body for the support. In the device 100 shown in Figure 3, the lamination device 15 uses a heat and pressure method, and therefore uses an Invar material with high thermal conductivity and dimensional stability. When the first substrate as the intermediate transfer body 1 is in the form of a belt, the thickness of the support may be, for example, 0.01 to 1.0 mm, or 0.05 to 0.5 mm.

[0042] There are no limitations on the method for forming a particle pattern on the intermediate transfer body. Common patterning techniques can be applied. In the apparatus shown in Figure 3, a 1.5 μm thick polyester film is placed on a glass pressure roller, and a mask with openings made by a UV laser is attached to the intermediate transfer body by the pressure roller. The surface of the intermediate transfer body, the attachment surface 21, has adhesive strength in a peelable state, which can be used to hold the mask in place.

[0043] Battery cathode material particles are applied as first particles to the non-formation areas of the mask, and when the mask film is peeled off, the particles adhere only to the mask openings, creating a pattern. Next, solid electrolyte particles are applied as second particles to the non-arrangement areas of the first particles remaining on the attachment surface 21, and the second particles selectively adhere to the areas where the first particles are not attached, i.e., the exposed areas of the attachment surface, completing a pattern using two particle materials.

[0044] Therefore, the method for manufacturing a stack of material layers includes a first step of forming a mask on the attachment surface 21. The means for forming the mask is not particularly limited, and may include, for example, a step of providing a mask layer 3 on the attachment surface 21 and a step of forming an opening 23 in the mask layer 3 to form a mask 22.

[0045] The apparatus shown in FIG. 3 includes, for example, a supply means for supplying the mask layer 3, a UV laser 6 as a means for forming openings 23 in the mask layer 3, and a pressure roller 4 as a means for attaching the mask 22 onto the attachment surface.

[0046] There are no limitations on the material of the mask layer 3, but a material that is uniform in thickness and easy to process is suitable. For example, plastics such as polyimide resin, polyacetal resin, and polyester resin, and metal foils such as aluminum, stainless steel (SUS), and invar alloy are available in the market as high-quality products, and these are suitable for use. Plastics are preferred.

[0047] The thickness of the mask is preferably selected to be equal to or less than the diameter of the particle material used. The arrangement of the first particles is not limited to a thin film equivalent to a particle monolayer, but is particularly suitable for forming a thin film equivalent to a particle monolayer. That is, the thickness of the arranged first particles may be, for example, 0.80 to 1.20 times, or 0.90 to 1.10 times the volume-based median diameter D50 of the first particles. The arranged first particles are preferably approximately a monolayer. This is because, in principle, a laminate made by stacking two-dimensionally patterned sheets with a thickness equivalent to a particle monolayer offers the greatest degree of freedom in particle pattern arrangement.

[0048] Within this range, the thicker the mask, the greater its durability, making it easier to handle and increasing the number of repeated uses. This is suitable for cases where there are few pattern changes or when producing large quantities. On the other hand, the thinner the mask, the less material is required, making it suitable for cases where there are many pattern changes or when producing small quantities. The thickness of the mask is preferably 0.05 to 1.10 times, more preferably 0.20 to 1.00 times, and even more preferably 0.20 to 0.50 times the volume-based median diameter D50 of the first particles. Examples of the thickness of the mask layer include 0.5 to 100 μm, 1 to 50 μm, and 1 to 5 μm.

[0049] The thickness of the mask is also preferably in a range of not less than the cumulative 10% particle size (D10) in the volumetric particle size distribution of the first particles and not more than the cumulative 90% particle size (D90) in the volumetric particle size distribution of the first particles. The volumetric median diameter D50 of the particles is the cumulative 50% particle size (median diameter: D50) in the volumetric particle size distribution. The particle size was measured using a laser diffraction / scattering particle size distribution analyzer (LA-960, manufactured by Horiba, Ltd.).

[0050] There are no limitations on the formation of the openings, and it is desirable to select an appropriate method depending on the material of the mask layer and the resolution of the design pattern. If few pattern changes and high resolution are desired, etching metal foil using photolithography is suitable, while if relatively low resolution is sufficient, creating openings in a resin film using a thermal head is suitable. The material layer production apparatus 100 in Figure 3 is equipped with a UV laser 6.

[0051] The shape of the mask portion is not particularly limited, but can be, for example, a stripe shape or a honeycomb shape. In the case of a stripe shape, the width of the opening is not particularly limited, but can be 1 to 200 μm or 2 to 100 μm. The width of the mask portion can be 1 to 200 μm or 2 to 100 μm.

[0052] The mask openings 23 may be formed with the mask attached to the intermediate transfer body 1, but from the viewpoint of protecting the surface of the particle-carrying layer from contamination and damage, it is preferable to form a mask layer 3 separately on a support member, form the openings, and then transfer it to the intermediate transfer body.

[0053] For example, a material with a lower absorption rate for the laser used than the mask layer is suitable for the support member used to form the opening. Specifically, glass is preferable to a thin plastic mask. Plastic has a higher absorption rate for CO2 lasers and UV lasers than glass. Glass is also suitable because it is a material that can easily be made into a highly smooth surface.

[0054] The manufacturing apparatus 100 shown in FIG. 3 uses a pressure roller 4 as a support member. The pressure roller 4 can be, for example, a glass cylinder. The support member can be flat, or it can be rolled if flexible materials such as polyimide film or SUS foil are used. The technology for processing glass cylinders with high precision is commonplace and is currently produced and utilized in a wide range of industries, making it easy to obtain. In the case of laser processing, the focal length significantly affects accuracy, so a high-precision glass cylinder is also preferred. The mask layer 3 transported on the pressure roller can be drilled to form openings 23.

[0055] 3, a polyester film, which is the material of the mask layer 3, wound in a roll, is fed by a pressure roller 4 while being irradiated with a laser 6 according to a design pattern, thereby performing perforation processing. Then, the mask is continuously attached to the intermediate transfer body 1, and the subsequent particle supply process and the mask peeling process are performed in an integrated manner, but the present invention is not limited to this.

[0056] For example, a configuration for batch processing of sheet-like films is also possible. The advantage of using a roller-shaped substrate for forming openings is that it can utilize the curvature, making it easier to handle the mask transfer. If the pressure roller is a rigid body such as glass, it may seem unsuitable for attaching a thin film mask to the surface of the intermediate transfer body 1, but if the particle-carrying layer on the surface of the intermediate transfer body 1 is elastic, attachment pressure can be applied without any problems.

[0057] In the apparatus of FIG. 3, two material particles are patterned using one mask, but if multiple masks are used, patterns of three or more types of materials can be produced.

[0058] Following the first step, a second step is carried out in which first particles are disposed in the non-mask-forming areas of the attachment surface 21. That is, a mask with openings is disposed on the intermediate transfer body 1, and then the first particles are disposed. There are no particular limitations on the particles used and the method for supplying the particles, and a wide range of known methods can be applied. Specifically, the particles can be sprinkled by gravity and spread by vibration, attached by spraying, or supplied using a roller, brush, or blade. If it is desired to densely fill the mask openings with particles, it is preferable to apply a rubbing force.

[0059] Among these, rubbing using magnetic particles is preferred when a mask is used. That is, the first particles are preferably arranged by using magnetic particles as a carrier material to support the first particles and then rubbing the first particles against the attachment surface 21. The first particles can be supported by forming a magnetic brush using magnetic particles as a carrier material. The rubbing force can be easily changed depending on the particles by controlling the magnetic force. Large magnetic particles are a good match because they can be filled while pressing the mask against the transfer body. The first particles may be a single material or a premix of multiple particles. Of course, the particle surfaces may be subjected to surface treatment or coating.

[0060] The apparatus 100 in Figure 3 has a cleaning roller 5 as a means for cleaning the surface of the mask layer 3 and ensuring close contact with the attachment surface 21. This acts to remove static electricity and ablation residues that may adhere during laser processing. This may not be necessary if the pattern is rough, but is effective for fine patterns.

[0061] In the apparatus 100 shown in Figure 3, the first particle supply unit 7 uses magnetic particles carrying material particles on their surface to rub against the patterning area by operating a backside magnet, thereby increasing particle density. Furthermore, an excess particle removal step for removing excess particles may be performed after the second step of disposing the first particles in the non-forming areas of the mask. The apparatus 100 shown in Figure 3 also includes an air blower 8 as an excess particle removal means for facilitating the removal of particles that have formed in two layers on the single-layer particle after the pattern is completed.

[0062] The particles are held to the intermediate transfer body by adhesive force at the interface, so that in principle they are held at a thickness equivalent to a single layer of particles, regardless of the patterning method used.

[0063] The method for manufacturing the material layer includes a third step of removing the mask from the deposition surface. The means for removing the mask is not particularly limited, and any known means may be used. For example, the mask may be peeled off. As a mechanism for peeling the mask from the first substrate, the apparatus shown in FIG. 3 uses a system in which the mask is wound up in the form of a continuous film using a peeling roller 9 and a winding device 10.

[0064] Next, a fourth step is performed in which second particles are placed in the non-placed areas of the first particles remaining on the attachment surface. That is, the second particles are placed in the mask-removed areas. The particle-carrying layer of the intermediate transfer body that was protected by the mask is now exposed, so the second particles selectively adhere to this area. The second particles may be the same as or different from the first particles.

[0065] As with the arrangement of the first particles, the supply method is not limited and can be selected according to the particles used. In FIG. 3, the production apparatus 100 includes a second particle supply unit 11. The second particle supply unit 11 may be the same as the first particle supply unit 7. After the second particles are supplied, excess particles may be removed in the same manner as after the arrangement of the first particles. For example, in FIG. 3, the production apparatus 100 includes an air blower 12.

[0066] In the apparatus shown in FIG. 3, a pattern consisting of two types of particles was formed using one mask, but this is not limiting. For example, if two masks are used, offset from one another, a pattern consisting of three types of particles can be obtained by repeating the same process.

[0067] Next, a binder that can be peeled from the attachment surface 21 is filled between the multiple particles arranged on the attachment surface 21. For example, a treatment liquid containing a binder dissolved therein is filled into the particle pattern on the intermediate transfer body. This allows for a material layer that is an integrated mixture of particles and binder. There are no restrictions on the method for supplying the treatment liquid containing the binder, and any known method can be used. In the apparatus shown in Figure 3, an air knife coater 13 is used as a means for applying the treatment liquid. From the perspective of maintaining a particle layer with a smaller amount of binder, a "contour coater" application method that applies excess treatment liquid on the particle layer in accordance with the surface shape, like an air knife coater, is preferred. It is also preferable that the liquid can be drained without contact.

[0068] Since the particles on the intermediate transfer body are held in place by the adhesiveness of the surface of the intermediate transfer body, the particle pattern may be disrupted if a "flattening coater" that applies a strong shear, such as a blade or reverse roller, is used. When using these, it is preferable to control the properties of the treatment liquid (mainly viscosity) and the conditions for draining the liquid (relative speed, gap, etc.).

[0069] The binder is not particularly limited as long as it is a material that can hold the particles and be peeled off from the adhesive layer. The binder is preferably a resin material, and more preferably a thermoplastic resin. Examples of binders include at least one selected from the group consisting of acrylic resins, polyester resins, polyolefin resins, vinyl resins such as ethylene vinyl acetate, fluorine-based resins such as polyvinylidene fluoride, cellulose-based resins such as carboxymethyl cellulose, rubber-based resins such as styrene-butadiene copolymer rubber, and polyalkylene oxide resins. The binder may also be a material having ionic conductivity. Furthermore, it may be a thermosetting resin, a UV-curable resin, or a resin curable by a two-component reaction. Among these, the binder preferably includes at least one selected from the group consisting of acrylic resins and polyalkylene oxide resins, and more preferably includes an acrylic resin.

[0070] The solvent in the binder-containing treatment liquid is not particularly limited, and may be selected appropriately from a solvent that has low compatibility with the surface to be adhered to. The solvent may be at least one selected from the group consisting of: aqueous solvents such as water; alcoholic solvents such as methanol, ethanol, propanol, isopropyl alcohol, butanol, ethylene glycol, propylene glycol, and glycerin; and organic solvents such as N-methyl-2-pyrrolidone (NMP), methyl ethyl ketone (MEK), chloroform, and dimethyl sulfoxide (DMSO). The solvent is preferably at least one selected from the group consisting of N-methyl-2-pyrrolidone (NMP) and methyl ethyl ketone (MEK).

[0071] The concentration of the binder in the binder-containing treatment liquid is not particularly limited, as long as it is within a range that allows the binder to be filled into the particles and form an integrated product. The amount of binder in the binder-containing treatment liquid is preferably 1 to 50 mass%, 2 to 20 mass%, or 2 to 10 mass%. The amount of binder relative to the particles, expressed as a volume ratio of binder to particle volume, is, for example, 0.1 to 2.0, preferably 0.2 to 1.0, and more preferably 0.3 to 0.5.

[0072] The device shown in Figure 3 uses N-methyl-2-pyrrolidone (NMP) as the solvent for the treatment liquid, a combination that has poor compatibility with the silicone rubber of the particle-carrying layer of the intermediate transfer body 1. At first glance, it may seem that the treatment liquid would be repelled by a surface with poor compatibility and that it would be impossible to apply a thin layer, but this is not a problem because the treatment liquid can penetrate into the gaps between the particles on the surface to be attached by capillary action. Therefore, if it is difficult to apply the treatment liquid to the surface to be attached, it is sufficient to make the particle surfaces lyophilic, rather than the surface to be attached.

[0073] The air knife coater 13 used in the apparatus shown in Figure 3 will be described with reference to Figure 4. The air knife coater 13 is configured with an air knife 41 positioned at an angle to the transport direction of the intermediate transfer body 1 and a binder liquid supply unit 42 located upstream. Binder liquid is continuously supplied from the binder liquid supply unit 42 located at the tip of the air knife 41, and the tilted air knife blows air to spread the liquid across the width and supply it to the entire surface of the particles on the intermediate transfer body 1 (the liquid flow is conceptually indicated by arrows). The processing liquid that has traversed the intermediate transfer body can be collected by a binder liquid recovery unit 43 located at the rear end of the air knife 41. In this apparatus, the surface of the intermediate transfer body is made of silicone rubber, so binder liquid is repelled from areas where particles are not attached. Therefore, binder liquid is applied only to areas where particles are attached, allowing the binder to fill the spaces between the particles.

[0074] Generally, it is extremely difficult to form a thin film that is a peelable integrated body of particles and binder. For example, when the treatment liquid and the attachment surface are compatible, a thin film can be formed, but peelability from the attachment surface may be reduced, i.e., transferability may be reduced. Conversely, when the treatment liquid and the attachment surface are not compatible, transferability may be ensured, but the treatment liquid is repelled, making it difficult to form a thin layer. This is a fundamental phenomenon that generally occurs when applying a slurry liquid in which particles and a binder liquid are mixed in advance. To resolve this contradictory relationship, the present disclosure uses a process in which the particles are first temporarily fixed to the attachment surface as a solid, and then the binder liquid is applied later.

[0075] To reiterate, this method is particularly suited to forming thin layers with high particle density. In other words, with the general slurry coating method mentioned above, creating a film with high particle density requires increasing the particle concentration in the slurry, which results in a high viscosity of the slurry. The higher the viscosity, the more difficult it becomes to apply a thin layer, especially on surfaces that are difficult to adhere to and tend to repel.

[0076] Although it is a binder liquid, there are no limitations on its use. Resin materials are preferred because they dissolve easily in solvents and the lower the viscosity of the solution, the easier it is to apply. As mentioned above, unlike a slurry liquid in which particles and binder liquid are premixed, it can be applied without containing particles, so it can be applied at a low viscosity, and there is no need for dispersion stabilization with the particles, so a wide variety of materials can be used depending on the purpose. The device in Figure 3 uses a thermoplastic acrylic binder that is easy to degrease and remove.

[0077] After the binder liquid is supplied, the solvent of the treatment liquid is removed as necessary to complete a material layer that is an integrated body of particles and binder. The apparatus shown in Figure 3 is equipped with a mechanism for heating the backside of the intermediate transfer body 1 with a hot plate as solvent removal promoting means 14. The thickness of the obtained material layer is not particularly limited, but is preferably 0.2 to 200 μm, more preferably 1 to 100 μm, even more preferably 2 to 50 μm, and even more preferably 5 to 20 μm.

[0078] Next, the obtained material layer is peeled from the attachment surface, and multiple material layers are stacked to obtain a stack of material layers. After peeling multiple material layers, the desired total number of material layers may be stacked to obtain a stack, or the stack may be obtained by repeatedly peeling and stacking material layers. In the apparatus of Figure 3, the stack is obtained by repeatedly peeling and stacking material layers. Here, when obtaining a material layer, the obtained material layer can be peeled from the attachment surface to obtain the material layer.

[0079] That is, a method for manufacturing a material layer according to one aspect of the present disclosure is a method for manufacturing a material layer, the method comprising the steps of: arranging a plurality of particles on an attachment surface of a first substrate having the attachment surface; filling a binder that is peelable from the attachment surface between the plurality of particles arranged on the attachment surface to obtain a material layer that is an integral body of the particles and the binder; and peeling the material layer from the attachment surface.

[0080] The means for peeling is not particularly limited, and a peeling roller or the like may be used, as with the mask 22, or any known means may be employed. In the present disclosure, the process for obtaining a laminate preferably includes a process of heating the material layer to bring the material layer into contact with a transfer target (transfer-receiving body), and then cooling the material layer as necessary to peel the material layer from the adhesive surface, thereby transferring the material layer to the transfer target. A laminate can be obtained by repeating the process of transferring the material layer to the transfer target. That is, the transfer target is the desired transfer material (e.g., a current collector) when the material layer is transferred for the first time, and the transfer target for the second or subsequent transfers is the material layer transferred in the previous process.

[0081] Although the integrated particle and binder material layer according to the present disclosure is brittle and difficult to peel, the heating and cooling process described above allows for better peeling, transfer, and lamination even with a small amount of binder. The heating temperature of the material layer during transfer is not particularly limited, as long as it can provide adhesion between the material layer and the transfer target. Examples include 80 to 300°C and 130 to 200°C. The cooling temperature during peeling is also not particularly limited, as long as it can peel the material layer from the adhesive surface. Examples include 25 to 180°C, 25 to 80°C, and 25 to 40°C. If peeling is possible without cooling, cooling is not necessary.

[0082] The apparatus 100 in Figure 3 has a lamination device 15 for laminating material layers. In the apparatus in Figure 3, the mask pattern is changed on demand, so particle patterns can be created in the designed lamination order, allowing for continuous, sequential lamination. In addition, the lamination device 15 has a rotation mechanism, so the lamination angle of the pattern can be changed for lamination. Depending on the shape and material of the pattern, the ease of pattern creation may change depending on the transport direction, so the angle and position can be changed here to address this.

[0083] Since the binder can develop surface tackiness (plasticity) when heated, the device shown in Figure 3 has a heater 16 located below the intermediate transfer body, and the heater at a predetermined temperature can be moved up and down (contact and removal) to heat the material layer on the intermediate transfer body 1. Once the binder has been heated to a state where it can be laminated, the material layer is pressed into contact with the object to be transferred (for example, aluminum foil that will become the current collector of a battery).

[0084] On the other hand, it is preferable to cool the material layer after contacting the material layer with the transfer target. Cooling tends to reduce the adhesion between the intermediate transfer body and the material layer. It is preferable to cool from the adhesion surface side of the material layer. In the device of Figure 3, in order to ensure transfer, a mechanism is provided that lowers the heater after pressure contact and blows air with a cooling fan 17 to lower the temperature of the intermediate transfer body. As the temperature decreases, the adhesiveness of the thermoplastic resin in the material layer decreases, and then the lamination device is raised to complete the transfer. This is repeated a predetermined number of times to complete the laminate of material layers.

[0085] In the device shown in Figure 3, the lamination device 15 is repeatedly brought into contact (preferably under pressure) with and separated from the material layer conveyed by the intermediate transfer body 1 at predetermined intervals, thereby repeatedly transferring the material layer and obtaining a laminate. In the transfer process, it is preferable to repeatedly heat the material layer, bring the material layer into contact with the transfer target, cool the material layer, and then separate the material layer. If the binder resin is a curable resin such as a thermosetting resin, a UV-curable resin, or a two-component curable resin, lamination and curing may be performed simultaneously in the process of obtaining the laminate. For example, in the case of a thermosetting resin, the binder resin can be cured by heating the material layer.

[0086] The lamination process is not limited to this example, and for example, the same pattern may be created multiple times for a certain number of sheets, and then the sheets may be laminated one by one while selecting a pattern later.The configuration of the device is also not limited to the flat plate pressure welding type shown in Figure 3, and a belt type rotary type or roller type may also be used.

[0087] Here, the surface of the transferred material layer, i.e., the surface that was in contact with the intermediate transfer body, has a characteristic shape. In other words, at least a portion of the particles that were sunk and held in the intermediate transfer body are exposed without being covered by the binder. In the slurry method, a typical conventional coating production method, functional particles are premixed with binder and solvent, so almost the entire particle surface is covered by the binder at the time of slurry production. Even a partial exposure of the functional particle surface allows for direct contact with the surface to which it is to be transferred. For example, when creating a three-dimensional wiring pattern using metal particles, the contact can be secured, resulting in low resistance, and in heat dissipation devices, the thermal conductivity can be improved, making this a feature that can be widely applied to a variety of applications.

[0088] Therefore, a material layer according to one aspect of the present disclosure is a material layer that is an integral body of a plurality of particles and a binder, wherein the binder is filled between the plurality of particles, and at least a portion of the plurality of particles is exposed from the binder on at least one surface of the material layer, and when the material layer is observed from the side where at least a portion of the plurality of particles is exposed, the ratio of the total area of ​​the exposed portions of the particles (hereinafter also referred to as the area ratio of the exposed portions) to the area of ​​the particle arrangement area where the plurality of particles are present is 1 to 70 area %.

[0089] The area ratio of the exposed portions is preferably 5 to 70 area%, more preferably 10 to 70 area%, and even more preferably 20 to 60 area%. An area ratio of 1 to 70 area% of the exposed portions can be achieved by the above-described method for manufacturing the material layer. For example, in the case of a material layer obtained by mixing particles and a binder resin and applying the mixture, the exposed portions will not appear, and the area ratio of the exposed portions is considered to be 0 area%.

[0090] FIG. 6A is a schematic diagram of a material layer observed from the side where the particles are exposed. The particle arrangement area 200 to be observed is indicated by a square. Multiple particles 201 are embedded, and particle exposed portions 210 are formed where the particles 201 are exposed from the binder 27. The particle buried portions 220, where the particles are buried, are indicated by dotted lines. The area ratio of the exposed portions is the ratio of the total area of ​​the particle exposed portions 210 to the area of ​​the particle arrangement area 200. It is preferable that at least a portion of the multiple particles is exposed from the binder on one surface of the material layer. FIG. 6B is a cross-sectional view of the material layer in the thickness direction. As described above, the particles 201 are exposed from one surface of the material layer.

[0091] Furthermore, the arrangement pitch 230 of the particle exposed portions 210 is preferably an interval of 25 to 400% of the particle diameter, and more preferably an interval of 50 to 200%. The arrangement pitch 230 of the particle exposed portions 210 is measured as follows. In the particle arrangement area 200, a line passing through the geometric centers of multiple particle exposed portions 210 is drawn. In Figure 6A, this line is represented by a dashed dotted line. For example, an angle of view is set so that several tens of particles or more can be observed, and the distance between the geometric centers of adjacent particle exposed portions is the arrangement pitch 230 of the particle exposed portions. It is preferable that the average distance of the arrangement pitch falls within the above range.

[0092] Furthermore, the appearance probability (appearance rate), which is the proportion of particles that form particle exposed portions among the particles contained in the particle arrangement area 200, is preferably 40 to 100% by number, more preferably 70 to 100% by number, and even more preferably 90 to 100% by number.

[0093] Such an arrangement pitch and probability of appearance of exposed portions can be achieved by the above-described method for manufacturing the material layer. For example, it is considered difficult to achieve such an arrangement pitch and probability of appearance of exposed portions by a conventional method, such as a material layer obtained by mixing particles and a binder resin and applying the mixture.

[0094] The area ratio of exposed portions, the arrangement pitch of exposed particle portions, and the occurrence probability of exposed portions can be obtained from information obtained by mapping the surface composition using X-ray photoelectron spectroscopy (XPS). The specific procedure is as follows: Mapping is performed by specifying components specific to the binder or particle material. Specifically, when an acrylic binder is used as the binder resin for LCO particles, exposed LCO portions can be confirmed in a Co (cobalt) mapping image. In a typical secondary electron image, exposed LCO portions appear white and binder components appear black due to differences in the conductive properties of the material. The observation area is preferably approximately 5 to 10 times the average particle diameter of the particles used. The observed image is binarized using a threshold value of 80 and then subjected to image processing. The area ratio of exposed LCO portions can be calculated from the number of white pixels / total number of pixels, the arrangement pitch can be calculated from the coordinate values ​​of the geometric centers of the individual particle exposed portions, and the occurrence probability can be calculated from the rate at which striped areas are detected at a specified arrangement pitch. In FIG. 6, the particles are shown as spherical particles as a model, but in reality, the image often looks like that shown in FIG.

[0095] The material layer is as described in the above-mentioned manufacturing method, and the plurality of particles preferably includes first particles and second particles. The plurality of particles may be particles of a single material, for example, a plurality of first particles. The material layer according to one embodiment of the present disclosure may be a material layer obtained by a manufacturing method for a material layer laminate according to one embodiment of the present disclosure. At least a portion of the plurality of particles may be exposed from the binder on both surfaces of the material layer, or at least a portion of the plurality of particles may be exposed from the binder on one surface of the material layer. In other words, at least one surface of the material layer has a surface made of the binder and particles exposed from the binder.

[0096] Although the material layer is an integrated body of particles and a binder, the embodiment of the material layer is not limited thereto, and the material layer may include other layers. For example, the present disclosure provides a laminate in which the material layer is held on an intermediate transfer body. The laminate may also be a laminate in which multiple material layers are stacked on an intermediate transfer body. In these laminates, the particle-exposed portion may be in contact with the intermediate transfer body, or the particle-exposed portion may form the outer surface of the laminate. Such a laminate embodiment allows the material layer to be transferred to a desired transfer target to form a desired particle structure.

[0097] The present disclosure also provides a laminate in which a material layer is supported on a current collector or a solid electrolyte. The laminate may also be a laminate in which multiple material layers are stacked on a current collector or a solid electrolyte. The particle-exposed portion may be in contact with the current collector or the solid electrolyte, or the particle-exposed portion may form the outer surface of the laminate. In such an embodiment, the desired electrode material can be formed by degreasing the binder of the material layer. The material layer may be a single-layer material layer, or a laminate in which multiple material layers are stacked.

[0098] The fabrication apparatus shown in FIG. 3 can fabricate a substantially single-layer particle pattern. Furthermore, this substantially single-layer particle pattern can be stacked to form a laminate. FIG. 5A shows an example of a laminate. Then, the binder 27 can be removed from the laminate 401 to obtain a particle laminate 402 (three-dimensional object 402) (FIG. 5B). Meanwhile, FIG. 5C shows a conventional laminate 501 in which particles arranged on a substrate are stacked as in the conventional method. Because the conventional laminate 501 has a large number of substrates, removing the substrates from the laminate 501 to obtain the particle laminate 502 (FIG. 5D) requires a great deal of effort. For example, removing the substrates by heating requires a large amount of heat.

[0099] Compared to the conventional laminate 501, the laminate 401 according to the present disclosure has less substrate and can obtain a particle laminate with less energy. The number of layers of the laminate is not particularly limited and can be changed depending on the purpose of the laminate.

[0100] In the present disclosure, the three-dimensional object 402 may be manufactured by removing the binder 27 from the laminate 401 and molding a three-dimensional object containing particles. The method for removing the binder is not particularly limited, but for example, a patterned laminate made of particles can be obtained by degreasing the laminate at high temperature. Therefore, the manufacturing method of the laminate preferably includes a step of heating the laminate to remove the binder.

[0101] When finally removing the binder, a highly removable binder should be selected depending on the removal method. The removal method should be selected depending on the characteristics of the particles used. For example, one method is to dissolve and remove the binder using a solvent, but the conditions should be selected so that the fluidity of the liquid does not disrupt the pattern. Another method is to use a photodegradable photosensitive material, but the conditions must be selected as the particles may block the light depending on the particle material. If the particle material is resistant to high temperatures, removal by heating can be selected. This method can be reproduced relatively easily by selecting the binder material. As mentioned above, one example is to use an acrylic resin as the binder.

[0102] The conditions for high-temperature degreasing are not particularly limited, but it is preferable to heat at a temperature equal to or higher than the thermal decomposition temperature of the binder, and it is preferable to heat at a temperature lower than the thermal decomposition temperature of each particle layer in the laminate. In the present disclosure, a lower temperature and shorter time can be set compared to high-temperature degreasing of conventional laminates. The temperature at which the laminate is heated is preferably 200°C or higher and 1000°C or lower, more preferably 300°C or higher and 600°C or lower, particularly preferably 300°C or higher and 500°C or lower, and even more preferably 300°C or higher and 400°C or lower.

[0103] The sintering temperature is preferably maintained for 10 minutes or more, more preferably 20 minutes or more. The upper limit is not particularly limited, but may be, for example, 3 hours or less, 1 hour or less, or 40 minutes or less. For example, the sintering temperature is preferably maintained for 10 minutes to 3 hours, 20 minutes to 1 hour, or 20 to 40 minutes.

[0104] The thermal decomposition temperature is the temperature at which the weight of a material begins to decrease when the temperature is gradually increased in a heating atmosphere in a sintering treatment device. Therefore, by heating the laminate at a temperature equal to or higher than the thermal decomposition temperature of the binder, the binder in the laminate can be decomposed, reducing its weight and removing the binder from the laminate.

[0105] In the present disclosure, the time required for the debinding process can be shortened by selecting a specific resin material as the binder. Shortening the debinding process not only improves production efficiency but also reduces the thermal load on the material particles, thereby suppressing, for example, degradation of the material particles. Setting a high heating rate during heating, for example, 10°C / min, in an attempt to shorten the debinding time can sometimes result in a decrease in properties and yield. This is believed to be due to the rapid decomposition within a narrow temperature range of the thermal decomposition temperature range, which generates a large amount of decomposition gas in a short period of time, disrupting the particle arrangement arranged during film formation. In response, selecting a resin that begins to decompose at a low temperature as the binder allows for rapid temperature increases. As a criterion for selecting a resin, a resin with a large weight loss ratio at 300°C or less is suitable. For example, when a resin material is subjected to thermogravimetry (TG) under a temperature increase condition of 10°C / min, the weight loss ratio at 100°C to 300°C calculated by the following formula is 40.0% by weight or more, preferably 50.0% by weight or more, more preferably 60.0% by weight or more, and particularly preferably 70.0% by weight or more. Weight loss ratio at 100 to 300°C = ((remaining weight at 100°C - remaining weight at 300°C) / (remaining weight at the start of measurement - remaining weight at 1000°C)) x 100

[0106] The upper limit of the weight loss rate at 100 to 300°C is not particularly limited, but the weight loss rate at 100 to 300°C may be 40.0 to 99.0 wt%, 50.0 to 99.0 wt%, 60.0 to 99.0 wt%, or 70 to 99.0 wt%. By selecting a resin that satisfies the above conditions as a binder, degreasing can be performed without rapid decomposition. The reason for not including temperatures below 100°C as an index is to eliminate the influence of water evaporation. The thermogravimetric measuring instrument used should conform to JIS K0129. Furthermore, it is preferable to match the measurement atmosphere to the actual degreasing atmosphere. The weight loss rate at 100 to 300°C can be controlled by the resin used.

[0107] This disclosure can be widely applied to functional materials, but one area in which it is particularly suitable is battery modules. Battery materials are expected to achieve higher performance by functionally arranging the materials in the electrode layers and efficiently arranging paths for ions and electrons. In particular, because all-solid-state batteries do not use electrolytes, this disclosure allows for the functional arrangement of positive and negative electrode materials and solid electrolyte materials according to optimized patterns.

[0108] The first particles are not particularly limited, and any desired resin particles, inorganic particles, etc. can be used. Examples of resin particles include (meth)acrylic resin particles, urethane resin particles, and ester resin particles. Metal particles such as copper particles may also be used. When the method for producing a material layer according to the present disclosure is used as a method for producing a precursor for a solid-state battery, it is preferable that the first particles contain at least one of active material particles and solid electrolyte particles.

[0109] The active material particles are not particularly limited, and known active material particles can be used. For example, a composite oxide containing lithium can be used. Specifically, for example, LiCoO ２ Li-Co oxide active material particles such as (lithium cobalt oxide), LiMO ２ (M is an element selected from the group consisting of Ni, Mn, and Co), ４ Oxide-based active material particles, lithium vanadium compounds (Li ３ V ２ (P.O. ４ ) ３, LiVOPO ４ ), olivine-type phosphate compounds (LiMPO ４ (M is one or more elements selected from the group consisting of Co, Ni, Mn, Fe, Mg, V, Nb, Ti, Al, and Zr). Active material particles that do not contain lithium may also be used. Specifically, for example, metal oxides (MnO ２ , V ２ O ５ etc.) and fluorides (FeF ３ , V.F. ３ Among them, Li-Co oxide-based active material particles, Li-PO ４ It is preferable that the negative electrode active material contains oxide-based particles. Alternatively, negative electrode active material particles such as graphite, Si, and lithium titanate (LTO) can also be used.

[0110] The solid electrolyte is not particularly limited, and known solid electrolytes can be used. For example, Li-B oxide-based solid electrolyte particles such as lithium borate, Li-Yb oxide-based solid electrolyte particles, and Nasicon-type solid electrolyte particles (LiAlTi(PO ４ ) ３ , LiAlGe (PO ４ ) ３ etc.), Li-P-O solid electrolyte particles (Li ３ P.O. ４ , LiPON (Li ３ P.O. ４ and the like) in which part of O is substituted with N. Among the above solid electrolyte particles, Li—B oxide-based solid electrolyte particles and Li—Yb oxide-based solid electrolyte particles are preferred.

[0111] The second particles are not particularly limited, and as with the first particles, desired resin particles, inorganic particles, etc. can be used. When the method for manufacturing a material layer of the present disclosure is used as a method for manufacturing a precursor for a solid-state battery, the second particles preferably include, for example, at least one of active material particles and solid electrolyte particles. Specifically, the active material particles and solid electrolyte particles described above as the first particles can be used.

[0112] The first particles and the second particles may each be of one type, or a combination of multiple types. When multiple types are combined, multiple types of particles may be premixed in advance. The particle surfaces may be subjected to a surface treatment or coating.

[0113] The method for manufacturing a stack of material layers according to the present disclosure can be used as a method for manufacturing a precursor for a solid-state battery, that is, the stack of material layers is preferably a precursor for a solid-state battery.

[0114] When the method for manufacturing a laminate of material layers according to the present disclosure is used as a method for manufacturing a precursor for a solid-state battery, it is preferable that the first particles include at least one of active material particles and solid electrolyte particles, and the second particles include at least one of active material particles and solid electrolyte particles. More preferably, the first particles include at least one of active material particles and solid electrolyte particles, and the second particles include the other of active material particles and solid electrolyte particles. Even more preferably, the first particles include active material particles, and the second particles include solid electrolyte particles.

[0115] Furthermore, an anisotropic conductive material layer can be obtained by using at least one of metal particles and resin particles as the first particles and the other of metal particles and resin particles as the second particles.

[0116] The precursor of the solid-state battery may be, for example, a material layer of the solid-state battery. The precursor of the solid-state battery is preferably a material layer of an electrode of the solid-state battery. Therefore, the method for manufacturing an electrode of the solid-state battery includes a step of heating and degreasing the laminate obtained by the above-mentioned manufacturing method to remove the binder and obtain an electrode.

[0117] That is, an electrode for a solid-state battery can be obtained by removing the binder from the laminate and forming a three-dimensional object containing particles. The above-mentioned processes can be used for the process of obtaining the laminate and the process of forming the three-dimensional object. The electrode may be a positive electrode or a negative electrode. The number of layers of the laminate is not particularly limited and can be changed depending on the purpose of the electrode to be manufactured. For example, three or more layers can be used.

[0118] The present disclosure will be specifically described below with reference to examples, but these examples are not intended to limit the present disclosure in any way. In the following formulations, parts are by mass unless otherwise specified.

[0119] Example 1 This example shows the fabrication of a positive electrode layer (single-material particles) for an all-solid-state battery using the fabrication apparatus shown in Figure 3. The particles used were cobalt lithium (Nippon Chemical Industry Co., Ltd.: volume-based median diameter D50: 5 μm) as the positive electrode material. Furthermore, a belt was used as the intermediate transfer member, consisting of a 0.1 mm thick polyamide film support and a 45 μm thick silicone rubber (KE44 manufactured by Shin-Etsu Chemical Co., Ltd.) coated on the support as a particle-carrying layer with an adhesive surface. The adhesive surface had a rubber hardness of 30° and a surface adhesion force of 0.25 mN / 20 mm. Magnetic particles (P02 manufactured by the Japanese Society of Imaging Science) were used for particle supply units 7 and 11. Furthermore, an acrylic resin (Orikox KC-1300 manufactured by Kyoeisha Chemical Co., Ltd.: 5% by mass NMP solution) was used as the binder liquid. Using the fabrication apparatus shown in Figure 3, the above-described steps were carried out to fabricate a positive electrode layer (film thickness 5.5 μm) for an all-solid-state battery. The obtained positive electrode material layer was observed with an electron microscope (Hitachi High-Technologies Corporation: S-4800) at an acceleration voltage of 15 kV and a magnification of 3000x (field of view approximately 400 μm x 300 μm), obtaining a secondary electron image of 200 x 256 pixels. Elemental mapping of Co (cobalt) was performed in the same observation field using an EDX analyzer (EDAX: Genesis 2000), and exposed LCO particles were confirmed by detecting a large amount of Co in the white islands in the image. The obtained secondary electron image was binarized with a threshold value of 80 and the ratio of white pixels was calculated. The area ratio of exposed LCO particles was 56.6 area%, the arrangement pitch of exposed particles was 65 to 122% of the particle diameter, and the occurrence probability of exposed particles was 91 number %.

[0120] Example 2: This example shows the fabrication of a positive electrode material layer for an all-solid-state battery using the fabrication apparatus shown in Figure 3. The first particles were a positive electrode material: lithium cobalt oxide (Nippon Chemical Industry Co., Ltd.: volume-based median diameter D50: 5 μm), and the second particles were a solid electrolyte: lithium borate (Toshima Manufacturing Co., Ltd.: volume-based median diameter D50: 5 μm). The intermediate transfer belt used was a 0.1 mm thick Invar support, coated with an 80 μm thick silicone rubber (Dow Toray Industries: SE9186) as a particle-carrying layer with an adhesive surface. The adhesive surface had a rubber hardness of 20° and a surface adhesion force of 0.5 mN / 20 mm. A polyester film (1.5 μm thick, Mitsubishi Chemical: K917) was used as the mask layer, and a UV laser processing machine (Kokyo: Fine UV Laser Marker) was used to create the mask openings. Magnetic particles (Japan Imaging Society: P02) were used for particle supply units 7 and 11. An acrylic resin (Kyoeisha Chemical: Oricox KC-1700: 5 mass% NMP solution) was used as the binder solution. The above-described steps were carried out using the production apparatus shown in FIG. 3 to produce a positive electrode material layer (film thickness 5.5 μm) for an all-solid-state battery. The mask openings were in a 10 μm stripe pattern with lines and spaces, i.e., the openings were in a stripe pattern with a width of 10 μm. Observation of the resulting positive electrode material layer revealed that the area ratio of the exposed portions was 17 area %, the arrangement pitch of the exposed particle portions was 60 to 131% of the particle diameter, and the occurrence probability of the exposed portions was 94% by number.

[0121] Then, following the preparation of the positive electrode material layer, the positive electrode material layer was peeled off and laminated using the lamination device 15 in the apparatus of FIG. 3. Specifically, three layers were laminated on an aluminum foil (20 μm thick) while shifting the lamination angle by 90 degrees (pressure welding temperature: 190°C, peeling temperature: 140°C) to obtain a laminate. The obtained laminate was heated and degreased at 350°C for 0.5 hours in an electric furnace (MMF-1 manufactured by AS ONE Corporation) to remove the binder, thereby producing a positive electrode material layer laminate (thickness: 15 μm) for an all-solid-state battery.

[0122] This cathode material laminate was used to prepare a prototype battery under the following conditions. A sintered body was obtained by processing and molding a solid electrolyte LAGP (Toshima Manufacturing Co., Ltd.) to a thickness of 250 μm and then sintering it at 850°C. The prepared cathode material laminate and a 50 μm thick indium metal foil as a negative electrode material were layered on both sides of the sintered body, and each was connected to an extraction electrode. The battery was vacuum-packed with an aluminum laminate sheet and finally pressurized at 200 MPa in a CIP device to obtain a prototype battery. The prototype battery was able to charge and discharge normally, and the charge capacity when charged and discharged at a charge / discharge rate of 0.1 C was 86% of the theoretical value. (Measured using an electrochemical device (Solartron Model 1255WB))

[0123] Comparative Example 1: As in Example 2, a pattern consisting of first particles and second particles was formed on an intermediate transfer member (as shown in Figure 2E). This pattern was transferred to a double-sided tape (Nitto Denko: No. 5600) as a substrate without using a binder solution to create a positive electrode material layer (film thickness 9.2 μm) for an all-solid-state battery. Three of the prepared positive electrode material layers were laminated (pressing temperature: room temperature) on aluminum foil (20 μm thick) while shifting the lamination angle by 90 degrees. The resulting laminate was degreased by heating at 350°C for 0.5 hours in an electric furnace (AS ONE: MMF-1), and the double-sided tape substrate was removed to create a positive electrode material layer laminate (thickness: 15 μm) for an all-solid-state battery. Battery characteristics were measured in the same manner as in Example 2, but the prototype battery had high resistance and did not function as a battery. The measurement was discontinued shortly after the start of the measurement because it exceeded the cutoff setting (3.6 V).

[0124] (Example 3) The positive electrode material layer (single layer) produced in Example 2 was degreased at 350°C for 0.5 hours, and the remaining amount of binder was evaluated from the mass ratio before and after degreasing. (The mass raw material ratio of particles only under the same degreasing conditions was measured separately, and the value was corrected for the weight loss due to the particles.) As a result, the remaining amount of binder after degreasing was 0.80 mass%, indicating a good degreasing state.

[0125] The positive electrode material layer (single layer) prepared in Comparative Example 1 was degreased at 350° C. for 0.5 hours, and the amount of remaining binder was evaluated from the mass ratio before and after degreasing. As a result, the amount of remaining binder was 96.04 mass %, meaning that almost no binder had been removed.

[0126] The positive electrode material layer (single layer) prepared in Comparative Example 1 was degreased at 450° C. for 0.5 hours, and the binder amount was evaluated from the weight ratio before and after degreasing. As a result, the remaining binder amount was 16.92 mass %, indicating insufficient removal.

[0127] The positive electrode material layer (single layer) prepared in Comparative Example 1 was degreased at 500° C. for 0.5 hours, and the remaining amount of binder was evaluated from the weight ratio before and after degreasing. As a result, the remaining amount of binder was 12.88 mass %, indicating that removal was still insufficient.

[0128] (Comparative Example 5) The positive electrode material layer (single layer) produced in Comparative Example 1 was degreased at 500°C for 1 hour, and the binder amount was evaluated from the weight ratio before and after degreasing. As a result, the remaining binder amount was 0.77 mass%, and the degreasing conditions for obtaining a value similar to that of Example 3 were identified, and heating at a high temperature for a long time was required.

[0129] Comparison of degreasing conditions and residual binder amounts in Example 3 and Comparative Examples 2 to 5

[0130] Example 4 A positive electrode material layer (film thickness 5.5 μm) for an all-solid-state battery was produced in the same manner as in Example 2, except that an acrylic resin (Kyoeisha Chemical: Oricox KC-1700 5 mass% MEK solution) was used as the binder liquid. The mask openings were in a 10 μm stripe pattern with lines and spaces. When the obtained positive electrode material layer was observed, the area ratio of the exposed portions was 46.6 area %, the arrangement pitch of the exposed particle portions was 57 to 137% of the particle diameter, and the occurrence probability of the exposed portions was 84 number %.

[0131] Then, following the preparation of the positive electrode material layer, the positive electrode material layer was peeled and laminated using the lamination device 15 in the apparatus of FIG. 3. Specifically, three layers were laminated on aluminum foil (20 μm thick) while shifting the lamination angle by 90 degrees (pressure welding temperature 190°C, peeling temperature 140°C) to obtain a laminate. After peeling and transfer of the laminate was completed, the transfer rate of the material layer was measured. Transfer rate = ((mass of intermediate transfer member with material layer attached - mass of intermediate transfer member after material layer transfer) / (mass of intermediate transfer member with material layer attached - initial mass of intermediate transfer member)) × 100. As a result, the average transfer rate of the three layers was a favorable value of 99.4% by mass. Furthermore, no problems occurred during transfer.

[0132] Example 5: This example shows the fabrication of an anisotropic conductive rubber laminate using the apparatus shown in Figure 3. The first particles were copper particles (in-house prototype: granulated by disk atomization and then sieved, volume-based median diameter D50: 30 μm), and the second particles were elastic particles: cross-linked polyacrylic ester (Sekisui Chemical Co., Ltd.: ARX-30, volume-based median diameter D50: 30 μm). The intermediate transfer belt used consisted of a 0.1 mm thick Invar support and an 80 μm thick silicone rubber (Dow Toray Industries, Inc.: SE9186) coating as a particle-carrying layer with an adhesive surface. The adhesive surface had a rubber hardness of 20° and a surface adhesion of 0.5 mN / 20 mm. The mask layer was made of SUS430 (30 μm thick), and a UV laser processing machine (Kokyo: Fine UV Laser Marker) was used to create the mask openings. The particle supply unit used a forward-rotating roller unit with a urethane rubber roller (rubber hardness 70 degrees). The binder liquid was an acrylic resin (Kyoeisha Chemical Co., Ltd.: Oricox KC-7000F 10% by mass NMP solution). The anisotropic conductive rubber laminate was then fabricated using the apparatus shown in Figure 3, carrying out the above-described steps. The mask openings were in a 100 μm stripe pattern with lines and spaces. Observation of the resulting material layer revealed that the area ratio of exposed portions was 34.1 area%, the arrangement pitch of the particle exposed portions was 43 to 167% of the particle diameter, and the occurrence probability of exposed portions was 71% by number.

[0133] Furthermore, from the mask application step to the mask peeling step, a magnet was placed on the back surface of the intermediate transfer body, and the mask was held in place by magnetic force. An anisotropically conductive rubber material laminate obtained by laminating 20 of the anisotropically conductive rubber material layers in the same lamination direction was able to be manufactured with stable quality as an anisotropically conductive rubber laminate with low resistance in the stripe direction.

[0134] (Examples 6 to 10, Reference Examples 6 to 8) Batteries were fabricated under the same conditions as in Example 2, except that the degreasing conditions were 500°C for 1 hour, the temperature increase rate was 20°C / min, and the binder resin was changed to one listed in Table 2. The results are shown in Table 2. The yield was calculated by determining that no 0.1C charge / discharge was observed as a failure. Examples using resins with a weight loss rate of more than 60.0% by weight between 100 and 300°C had a high yield. The weight loss rate between 100 and 300°C was calculated by measuring the weight loss of each resin up to 1000°C at a temperature increase rate of 10°C / min using a simultaneous differential thermal and thermogravimetric analyzer (STA200RV, manufactured by Hitachi High-Tech Corporation). The weight at the start of the measurement (100°C) was set to 100, and the weight remaining at 1000°C was set to 0. The weight remaining at 100°C and 300°C was then substituted into the following formula: Weight loss rate from 100 to 300°C = ((remaining weight at 100°C - remaining weight at 300°C) / (remaining weight at the start of measurement - remaining weight at 1000°C)) x 100

[0135] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the present disclosure. Therefore, the following claims are appended to clarify the scope of the present disclosure. This application claims priority based on Japanese Patent Application No. 2024-020975 filed on February 15, 2024, and Japanese Patent Application No. 2025-012080 filed on January 28, 2025, the entire contents of which are incorporated herein by reference.

Claims

1. A method for manufacturing a laminate of material layers, comprising the steps of: arranging a plurality of particles on an attachment surface of a first substrate having the attachment surface; filling a binder that can be peeled from the attachment surface between the plurality of particles arranged on the attachment surface to obtain a material layer that is an integral body of the particles and the binder; and peeling the material layer from the attachment surface and stacking a plurality of the material layers to obtain a laminate of material layers.

2. A method for manufacturing a stack of material layers as described in claim 1, wherein the step of arranging a plurality of particles on the attachment surface comprises: a first step of forming a mask on the attachment surface; a second step of arranging first particles in areas of the attachment surface where the mask is not formed; a third step of removing the mask from the attachment surface; and a fourth step of arranging second particles in areas where the first particles remaining on the attachment surface are not arranged.

3. The method for manufacturing a stack of material layers according to claim 2, wherein the first particles include at least one of active material particles and solid electrolyte particles, and the second particles include at least one of active material particles and solid electrolyte particles.

4. A method for manufacturing a laminate of material layers according to any one of claims 1 to 3, wherein the adhesive strength of the adhesive surface measured by a peeling analysis device is 0.2 to 10 mN / 20 mm.

5. A method for producing a laminate of material layers according to any one of claims 1 to 4, wherein the first base material has a support and a particle-carrying layer laminated on the support to form the attachment surface, and the particle-carrying layer contains at least one selected from the group consisting of silicone rubber, urethane rubber, and fluororubber.

6. The method for producing a laminate of material layers according to claim 5, wherein the particle-carrying layer contains 10 to 100% by mass of the silicone rubber.

7. A method for manufacturing a laminate of material layers according to any one of claims 1 to 6, wherein the rubber hardness of the adhesion surface measured in accordance with JIS K6253-3:2012 is 10° to 80°.

8. A method for producing a laminate of material layers according to any one of claims 1 to 7, wherein the step of obtaining the laminate includes the steps of heating the material layer to bring the material layer into contact with a transfer target, cooling the material layer to separate the material layer from the adhesive surface, and transferring the material layer to the transfer target.

9. A method for producing a laminate of material layers according to any one of claims 1 to 8, further comprising the step of heating the laminate to remove the binder.

10. The method for manufacturing a stack of material layers according to claim 3, wherein the stack of material layers is a precursor to a solid-state battery.

11. A method for manufacturing an electrode for a solid-state battery, the method comprising the step of heating and degreasing the laminate obtained by the method for manufacturing a laminate of material layers described in claim 3 to remove the binder, thereby obtaining the electrode.

12. A material layer which is an integral body of a plurality of particles and a binder, wherein the binder is filled between the plurality of particles, and at least a portion of the plurality of particles is exposed from the binder on at least one surface of the material layer, and when the material layer is observed from the side where at least a portion of the plurality of particles is exposed, the ratio of the total area of ​​the exposed portions of the particles to the area of ​​the particle arrangement area where the plurality of particles are present is 1 to 70 area %.

13. The material layer according to claim 12, wherein the plurality of particles include first particles and second particles, the first particles include at least one of active material particles and solid electrolyte particles, and the second particles include at least one of active material particles and solid electrolyte particles.

14. The material layer according to claim 12 or 13, wherein the binder is a resin material, and when the resin material is subjected to thermogravimetry at a temperature increase rate of 10°C / min, the weight loss rate at 100 to 300°C calculated by the following formula is 40.0% by weight or more: Weight loss rate at 100 to 300°C = ((remaining weight at 100°C - remaining weight at 300°C) / (remaining weight at the start of measurement - remaining weight at 1000°C)) x 100 15. A method for manufacturing a material layer, comprising the steps of: arranging a plurality of particles on an attachment surface of a first substrate having the attachment surface; filling a binder that is peelable from the attachment surface between the plurality of particles arranged on the attachment surface to obtain a material layer that is an integral body of the particles and the binder; and peeling the material layer from the attachment surface.

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