Electrode base material, electrode base material laminate, electrode, secondary battery, and method for manufacturing same

Abstract

Provided are an electrode base material, an electrode base material laminate, an electrode, a secondary battery, and a method for manufacturing the same, which have excellent ion conductivity while relaxing volume fluctuation of active material particles, and make it possible to suppress a decrease in output. The electrode base material is used for manufacturing an electrode and comprises a resin base material, active material particles, and solid electrolyte particles, wherein: when the average equivalent circle diameter of the active material particles is ra and the average equivalent circle diameter of the solid electrolyte particles is re, re / ra is in a specific range; when particles having a particle size that exceeds a specific particle diameter among the solid electrolyte particles are first solid electrolyte particles and particles that are equal to or less than the specific particle size are second solid electrolyte particles, and the active material particles and the first solid electrolyte particles are arranged adjacent to each other, 80% or more of the second solid electrolyte particles are arranged so as to be unevenly distributed on the side of contact with the resin base material or on the opposite side with respect to a reference line at a specific position in cross-sectional observation of the particle layer.

Description

Electrode substrate, electrode substrate laminate, electrode and secondary battery, and method for manufacturing the same

[0001] The present disclosure relates to an electrode substrate, an electrode substrate laminate, an electrode and a secondary battery, and a method for manufacturing the same.

[0002] Generally, secondary batteries are composed of electrodes (positive and negative electrodes) and an electrolyte, and charge and discharge occur through the movement of ions between the electrodes via the electrolyte. Such secondary batteries are used in a wide range of applications, from small devices such as mobile phones to large devices such as electric vehicles. Therefore, further improvement in the performance of secondary batteries is required.

[0003] In recent years, research and development of so-called all-solid-state batteries, which use inorganic solid electrolytes, has progressed. By replacing conventional organic electrolytes with solid electrolytes, all-solid-state batteries are expected to improve the safety and capacity and output of secondary batteries. However, in all-solid-state batteries, the volume fluctuations of active material particles during the ion intercalation and deintercalation process in the electrodes can easily disrupt the conduction paths within the electrodes, particularly between the electrode and the current collector, and between the electrode and the electrolyte. As a result, deterioration during repeated charging and discharging can easily occur, leading to a decrease in so-called cycle characteristics. Therefore, a technology has been developed to provide a buffering section within the electrode to mitigate the effects of this volume fluctuation.

[0004] Patent Document 1 discloses an electrode having a plurality of ceramic crystal grains of an electrode active material or solid electrolyte material, with aggregates of carbon particles having voids at the grain boundaries between the crystals.

[0005] Japanese Patent Application Laid-Open No. 2021-002482

[0006] However, according to the inventors' research, while voided carbon particle aggregates tend to form at the interface between large ceramic crystal particles, they tend not to form at the interface between small ceramic crystal particles, which tend to aggregate. In other words, at the interface between ceramic crystal particles, there are sparse areas where voided carbon particle aggregates form and areas where no aggregates form, making it difficult to create a uniform buffer zone within the electrode, and thus the impact of volume fluctuations is not sufficiently mitigated. On the other hand, it has been found that increasing the ratio of the aggregates to the ceramic crystal particles for this purpose tends to hinder ionic conduction and reduce output power.

[0007] Therefore, at least one aspect of the present disclosure is directed to providing an electrode substrate, an electrode substrate laminate, an electrode, and a secondary battery that have excellent ion conductivity while mitigating the effects of volume fluctuations of active material particles and that can suppress a decrease in output. Another aspect of the present disclosure is directed to providing methods for manufacturing an electrode substrate, an electrode substrate laminate, an electrode, and a secondary battery.

[0008] According to at least one aspect of the present disclosure, there is provided an electrode substrate used in manufacturing an electrode, the electrode substrate comprising: a resin substrate; and active material particles and solid electrolyte particles on the resin substrate; and a particle layer comprising the active material particles and the solid electrolyte particles is formed on the resin substrate; when an average equivalent circular diameter ra of the active material particles is a number-based cumulative 50% particle diameter calculated from a distribution of equivalent circular diameters of primary particles of the active material particles, and when an average equivalent circular diameter re of the solid electrolyte particles is a number-based cumulative 50% particle diameter calculated from the distribution of equivalent circular diameters of primary particles of the solid electrolyte particles, the ratio of the average equivalent circular diameter re to the average equivalent circular diameter ra (re / ra) is 0.01 or more and 2.0 or less; and when, among the solid electrolyte particles, particles having a particle diameter exceeding a cumulative 10% particle diameter on a number basis from the smaller particle diameter side in the distribution of equivalent circular diameters of primary particles of the solid electrolyte particles are referred to as first solid electrolyte particles, and particles having a particle diameter equal to or less than the cumulative 10% particle diameter are referred to as second solid electrolyte particles, in the particle layer, the active material particles and the first solid electrolyte particles are disposed adjacent to each other; in a cross-sectional observation of the particle layer, 80% or more by number of the second solid electrolyte particles are unevenly distributed on the side of the particle layer that contacts the resin substrate or on the side opposite to the resin substrate, with respect to a reference line; and the reference line indicates a peak position of the distribution of the active material particles in the particle layer in the stacking direction of the resin substrate and the particle layer.

[0009] According to at least one embodiment of the present disclosure, there is provided an electrode substrate laminate in which a plurality of the electrode substrates are laminated.

[0010] According to at least one aspect of the present disclosure, there is provided an electrode for a secondary battery, the electrode being a sintered body of the above-described electrode base material, or an electrode being a sintered body of an electrode base material laminate in which a plurality of the above-described electrode base materials are laminated.

[0011] According to at least one embodiment of the present disclosure, there is provided a secondary battery comprising an electrode that is a sintered body of the electrode substrate, and an electrolyte layer adjacent to the electrode.

[0012] According to at least one aspect of the present disclosure, there is provided a method for manufacturing an electrode base material used in manufacturing an electrode, the method comprising: a step of preparing the resin base material having an adhesive portion; a step of arranging the active material particles and the first solid electrolyte particles on surfaces of the adhesive portion; a particle settling step of settling the first solid electrolyte particles and the active material particles arranged on the surfaces of the adhesive portion into the adhesive portion; and a step of arranging second solid electrolyte particles in the adhesive portion between the settled first electrolyte particles and the active material particles.

[0013] a method for producing an electrode base material used in producing an electrode, the electrode base material comprising: active material particles and solid electrolyte particles on a resin base material; a particle layer comprising the active material particles and the solid electrolyte particles formed on the resin base material; an average equivalent circular diameter ra of the active material particles being a number-based cumulative 50% particle diameter calculated from a distribution of equivalent circular diameters of primary particles of the active material particles; and an average equivalent circular diameter re of the solid electrolyte particles being a number-based cumulative 50% particle diameter calculated from the distribution of equivalent circular diameters of primary particles of the solid electrolyte particles; a ratio (re / ra) of the average equivalent circular diameter re to the average equivalent circular diameter ra being 0.01 or more and 2.0 or less; the solid electrolyte particles comprising solid electrolyte particles P2 and solid electrolyte particles P3; and a cumulative 50% particle diameter (r50) in a volume-based particle size distribution of the primary particles of the solid electrolyte particles P2 being larger than a cumulative 50% particle diameter (r50) in a volume-based particle size distribution of the primary particles of the solid electrolyte particles P3; The manufacturing method for an electrode base material includes the steps of: preparing the resin substrate having an adhesive portion on its surface; arranging the active material particles and the solid electrolyte particles P2 adjacent to each other on the surface of the adhesive portion; a particle settling step of settling the solid electrolyte particles P2 and the active material particles arranged on the surface of the adhesive portion into the adhesive portion; and arranging the solid electrolyte particles P3 in the adhesive portion between the settled solid electrolyte particles P2 and the active material particles.

[0014] According to at least one aspect of the present disclosure, there is provided a method for manufacturing an electrode, comprising the steps of: stacking a plurality of the electrode base materials described above to form a laminate; removing the resin base material from the laminate to obtain a three-dimensional object; and pressurizing the three-dimensional object to obtain an electrode. Furthermore, according to at least one aspect of the present disclosure, there is provided a method for manufacturing a secondary battery, comprising the steps of preparing an electrode by the above-described electrode manufacturing method; and stacking the electrode, a current collector, and an electrolyte.

[0015] According to at least one aspect of the present disclosure, there are provided an electrode substrate, an electrode, and a secondary battery that have excellent ion conductivity while mitigating volume fluctuations of active material particles and can suppress a decrease in output, as well as methods for manufacturing the electrode substrate, the electrode, and the secondary battery.

[0016] FIG. 1 is an image diagram showing a manufacturing method of an electrode substrate. FIG. 2 is a diagram schematically showing the configuration of a particle arrangement device 1. FIG. 3 is a diagram schematically showing the configuration of a filling device. FIGS. 4A to 4C are schematic diagrams showing the stages of the state of the filler being conveyed on a first substrate. FIG. 5 is an enlarged view of the vicinity of the surface of a first substrate. FIG. 6A is a diagram schematically showing the configuration of a filling device when brush fibers are used as the carrier material, and FIG. 6B is a diagram schematically showing the configuration of a filling device when an elastic material is used as the carrier material. FIG. 7 is a diagram schematically showing the configuration of a transfer unit. FIG. 8 is an enlarged view of the vicinity of the surface of a second substrate during a filling process using a second filling device. FIG. 9A is a diagram schematically showing the second substrate after the first particles P1 have been transferred, and FIG. 9B is a diagram schematically showing the second substrate after the second particles P2 have been filled. FIG. 10 is a diagram schematically showing the configuration of a particle arrangement device 2. FIG. 11 is a diagram schematically showing each device in the third and fourth steps in the manufacturing method of an electrode base material. FIG. 12A is a diagram schematically showing a cross section of a substrate before the third step in which first particles P1 and second particles P2 are precipitated on the substrate, and FIG. 12B is a diagram schematically showing a cross section of the substrate after the third step. FIG. 13 is a diagram schematically showing a substrate from above (particle layer side) after the third step in the manufacturing method of an electrode base material. FIG. 14 is a diagram schematically showing a substrate from above (particle layer side) after the fourth step in the manufacturing method of an electrode base material. FIG. 15 is a diagram schematically showing a third filling device that does not use a belt device. FIG. 16 is a diagram schematically explaining the operation of the filling device. FIG. 17 is an image diagram showing a manufacturing method of an electrode. FIG. 18 is a diagram schematically showing the configuration of a laminate forming device. FIG. 19 is a diagram schematically showing the configuration of a sintering treatment device. Fig. 20A is an SEM image of a cross section of a laminate after the first step of the electrode manufacturing method, Fig. 20B is an SEM image of a cross section of a three-dimensional object after the second step, and Fig. 20C is an SEM image of the top of the three-dimensional object. Fig. 21 is a diagram schematically showing the overall configuration of an additive manufacturing system. Fig. 22A is a diagram schematically showing the structure of the top surface of a first substrate having a concavo-convex pattern formed on its surface, and Fig. 22B is a cross-sectional view taken along the line A-A in Fig. 22A. Fig. 23A is an SEM image of the top of the electrode substrate of Example 1, Fig. 23B is an enlarged image of Fig. 23A, and Fig. 23C is an SEM image of the cross section of the electrode substrate of Example 1.FIG. 24A is an SEM image of the upper part of the electrode substrate of Comparative Example 2, and FIG. 24B is an SEM image of the cross section of the electrode substrate of Comparative Example 2. FIG. 25A is an SEM image of the upper part of the electrode substrate of Comparative Example 5, and FIG. 25B is an SEM image of the cross section of the electrode substrate of Comparative Example 5. FIG. 26 is a BIB-SEM image of the cross section of an electrode manufactured using the electrode substrate of Example 1. FIG. 27 is a schematic diagram of an electrode substrate manufactured using the electrode substrate of Example 1. FIG. 28 is a BIB-SEM image of the cross section of an electrode manufactured using the electrode substrate of Comparative Example 2. FIG. 29 is a BIB-SEM image of the cross section of an electrode manufactured using the electrode substrate of Comparative Example 5. FIG. 30 is a diagram showing an example of an SEM image of the upper surface (particle layer side) of the electrode substrate. FIG. 31 is a diagram showing an example of an image used to calculate the cover ratio. FIG. 32 is a diagram showing an example of a cross-sectional image of an electrode substrate photographed with an electron microscope. FIG. 33A is an example of an image cut out from an SEM image used to calculate ra to represent only the particle layer, FIG. 33B is an example of a binarized image, FIG. 33C is an example of an image with noise removed, and FIG. 33D is an example of an image after each particle has been detected. FIG. 34A is an example of an image binarized from an SEM image used to calculate re, FIG. 34B is an example of an image in which only solid electrolyte particles are represented by white pixels, FIG. 34C is an example of an image with noise removed, FIG. 34D is an example of an image in which white areas have been expanded, FIG. 34E is an example of an image showing a boundary region, and FIG. 34F is an example of an image after each particle has been detected. FIG. 35 is a diagram showing an example of a BIB-SEM image and a peak in the distribution of active material particles. FIG. 36 is a diagram showing an example of the center position and reference line of the second solid electrolyte particle.

[0017] In the present disclosure, the expressions "XX to YY" and "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints, unless otherwise specified. When a numerical range is described in stages, any combination of the upper and lower limits of each numerical range is also disclosed.

[0018] When an inorganic solid electrolyte is used as the electrolyte, the active material and the electrolyte come into contact in a solid-state state, making it difficult to obtain a sufficient contact area and form an interface. In particular, if the active material aggregates, the aggregated active material has even less contact with the solid electrolyte, making it more likely to reduce ionic conductivity. Furthermore, as mentioned above, the active material particles undergo volume fluctuations during the ion insertion / extraction process. This volume fluctuation easily disrupts the conduction paths within the electrode, particularly between the electrode and the current collector and between the electrode and the electrolyte, leading to a deterioration in cycle performance.

[0019] To solve the above-mentioned problems, the inventors investigated a structure that can form a good interface between the active material and the electrolyte while providing a layer inside the electrode that mitigates the effects of volumetric fluctuations of the active material. As a result of this investigation, they found that it is important to provide uniform voids inside the electrode to mitigate the effects of volumetric fluctuations of the active material, while providing uniform dense portions in the vicinity of the voids to ensure sufficient contact between the active material and the electrolyte and maintain ionic conductivity. Specifically, it is believed to be important to control the arrangement of each particle in the electrode substrate so that specific electrolyte particles are unevenly distributed within the electrode. By unevenly distributing specific electrolyte particles in the electrode substrate, a structure can be achieved in which uniform dense portions of the electrolyte particles are provided on the substrate side or the opposite side of the substrate of the electrode substrate, and uniform voids are provided on the opposite side of the dense portions. By manufacturing an electrode using an electrode substrate with such a configuration, ions can be easily conducted from the active material particles to the electrolyte while mitigating the effects of volumetric fluctuations of the active material particles inside the electrode. Furthermore, secondary batteries using such electrodes can suppress a decrease in output even when repeatedly charged and discharged.

[0020] In the present disclosure, the above-described configuration is achieved by using an electrode substrate in which active material particles and solid electrolyte particles are arranged on a resin substrate with the characteristics of the present disclosure. A plurality of electrode substrates can be stacked to form an electrode substrate laminate. The electrode substrate and electrode substrate laminate can also be used as electrode materials. In the present disclosure, the mitigation of volume fluctuation is conveniently evaluated using an index known as the "cycle characteristics" of a prototype battery, and the ionic conductivity is conveniently evaluated using an index known as the "rate characteristics" of a prototype battery. The electrode substrate, electrode substrate laminate, electrode, and secondary battery using them, as well as a method for manufacturing the same, are described in detail below.

[0021] The electrode substrate of the present disclosure can be used in the manufacture of electrodes for secondary batteries. Hereinafter, a positive electrode substrate using positive electrode active material particles will be described as an example, but the electrode substrate of the present disclosure can be used for both positive and negative electrodes. The electrode substrate includes a resin substrate, active material particles on the resin substrate, and solid electrolyte particles. A particle layer including the active material particles and the solid electrolyte particles is formed on the resin substrate.

[0022] The resin substrate is a substrate formed from a material containing resin. Using a substrate formed from an organic material such as resin as the substrate can facilitate removal of the substrate by heating in the manufacturing process of the electrode substrate, which will be described later. The resin contained in the material of the resin substrate is not particularly limited, but examples thereof include polyesters such as polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), as well as polyamides such as nylon. Among these, PET is preferably used from the viewpoints of its decomposition temperature and the low toxicity of gases generated during thermal decomposition.

[0023] The active material particles are not particularly limited and may be any known material. For example, a composite oxide containing lithium may be used. Specifically, for example, LiCoO ２ Li-Co oxide active material particles such as 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 V２ (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). A lithium-free positive electrode active material may also be used. Specifically, for example, a metal oxide (MnO ２ , V ２ O ５ etc.) and fluorides (FeF ３ , V.F. ３ When using a positive electrode active material that does not contain lithium, it can be used by discharging the negative electrode active material first, using metallic lithium containing lithium or a negative electrode active material doped with lithium ions.

[0024] The present inventors have revealed that, among the above-mentioned positive electrode active material particles, the use of Li-Co oxide-based active material particles increases the surface area of ​​the positive electrode active material particles and improves the output characteristics of secondary batteries (JP 2020-198301 A). Furthermore, Li-PO4 oxide-based active material particles are very stable due to the strong covalent bond between P—O and the suppression of oxygen release. Therefore, among the above-mentioned positive electrode active material particles, it is preferable to include Li-Co oxide-based active material particles and Li-PO4 oxide-based active material particles.

[0025] The active material particles may be commercially available products or may be prepared separately. Examples of the Li-Co oxide active material particles include Cellseed C-5H (trade name, manufactured by Nippon Chemical Industry Co., Ltd.) (LiCoO ２ ) can be used. ２ (M is an element selected from the group consisting of Ni, Mn, and Co) Cellseed NMC (trade name, manufactured by Nippon Chemical Industry Co., Ltd.) (LiNi （１－ｘ－ｙ） Mn ｘ Co ｙ O ２ ) and the like can be used. ４ The oxide-based active material particles include LiFePO ４(manufactured by Toshima Manufacturing Co., Ltd.) or the like can be used. ４ When using active material particles having low electronic conductivity such as those described above, the particle surfaces may be coated with carbon by a general method before use. The active material particles may be used alone or in combination of two or more.

[0026] The solid electrolyte particles are not particularly limited, and ion-conductive solids that are commonly used in all-solid-state batteries can be used. For example, Li-B oxide-based solid electrolyte particles, Li-Yb oxide-based solid electrolyte particles, 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 Examples of the solid electrolyte particles include Li-B oxide-based solid electrolyte particles and Li-Yb oxide-based solid electrolyte particles, which can be sintered at relatively low temperatures (700°C or lower), thereby suppressing reaction with the positive electrode active material particles during sintering and maintaining ionic conductivity. For this reason, among the solid electrolyte particles, it is preferable to include Li-B oxide-based solid electrolyte particles and Li-Yb oxide-based solid electrolyte particles.

[0027] The solid electrolyte particles may be commercially available products or may be prepared separately as materials. Examples of the Li-B oxide solid electrolyte particles include Li ３ BO ３ (Toshima Manufacturing Co., Ltd.) and Li ３ BO ３ Particles in which part of O is replaced with C can be used. In addition, as the Li-Yb oxide-based solid electrolyte particles, for example, Li ５．９ Yb ０．８１ La ０．０９ Zr ０．１ (BO ３ ) ３ etc. can be used.

[0028] The cumulative 50% particle size (number basis) calculated from the distribution of equivalent circle diameters of primary particles of the active material particles is defined as the average equivalent circle diameter ra of the active material particles. The cumulative 50% particle size (number basis) calculated from the distribution of equivalent circle diameters of primary particles of the solid electrolyte particles is defined as the average equivalent circle diameter re of the solid electrolyte particles. The equivalent circle diameter refers to the diameter of a sphere (circle) having a volume (area) equal to the volume (area) of the particle. Note that ra and re are determined by processing a cross section with a broad ion beam (BIB) using Ar, and then obtaining a two-dimensional image of the cross section using a scanning electron microscope. Hereinafter, the observation method for the two-dimensional image described above will be referred to as BIB-SEM. Details of the measurement method will be described later.

[0029] In an electrode substrate, among the solid electrolyte particles, particles having a particle size exceeding the cumulative 10% particle size (re10) on a number basis from the smallest particle size side in the distribution of the equivalent circle diameters of primary particles of the solid electrolyte particles are referred to as first solid electrolyte particles. Furthermore, particles having a particle size equal to or smaller than the cumulative 10% particle size are referred to as second solid electrolyte particles. That is, the second solid electrolyte particles are a group of particles having a smaller equivalent circle diameter of primary particles than the first solid electrolyte particles among all solid electrolyte particles. By disposing the first solid electrolyte particles and the second solid electrolyte particles in specific regions of the electrode substrate using the method described below, it is possible to provide uniform voids and uniform dense portions within the electrode. As a result, ions are more easily conducted from the active material particles to the electrolyte while mitigating the effects of volume fluctuations of the active material particles within the electrode.

[0030] The equivalent circle diameter of the primary particles of the first solid electrolyte particles is not particularly limited, but is preferably, for example, 1 to 100 μm, and more preferably 2 to 50 μm. The equivalent circle diameter of the primary particles of the second solid electrolyte particles is not particularly limited as long as it is smaller than that of the first solid electrolyte particles, but is, for example, preferably ½ or less, and more preferably ⅓ or less, of the equivalent circle diameter of the first solid electrolyte particles. The ratio of the equivalent circle diameter of the primary particles of the second solid electrolyte particles to the equivalent circle diameter of the primary particles of the first solid electrolyte particles (equivalent circle diameter of second solid electrolyte particles / equivalent circle diameter of first solid electrolyte particles) is not particularly limited, but is, for example, preferably 0.50 or less, and more preferably 0.30 or less.

[0031] The electrode substrate has a particle layer formed on a resin substrate, the particle layer including active material particles and solid electrolyte particles. Furthermore, in the particle layer, the active material particles and first solid electrolyte particles are arranged adjacently. This arrangement provides a uniformly dense portion between the active material particles and the solid electrolyte particles, allowing sufficient contact between the active material particles and the solid electrolyte particles. As a result, ionic conductivity can be improved. For example, by the method described below, first particles P1 as active material particles and second particles P2 that can correspond to the first solid electrolyte particles are arranged on a resin substrate that serves as the material for the electrode substrate. This allows the active material particles and the first solid electrolyte particles to be controlled so that they are arranged adjacently in the electrode substrate. The formation of a particle layer in the electrode substrate and the adjacent arrangement of the active material particles and the first solid electrolyte particles can be confirmed, for example, by observation using an SEM.

[0032] Furthermore, in cross-sectional observation of the particle layer, 80% or more by number of the second solid electrolyte particles are unevenly distributed on the side of the particle layer that contacts the resin substrate (one side in the stacking direction of the resin substrate and the particle layer in the particle layer) or on the opposite side from the resin substrate side (the other side in the stacking direction of the resin substrate and the particle layer in the particle layer) with respect to the reference line. The reference line indicates the peak position of the distribution of the active material particles in the particle layer in the stacking direction of the resin substrate and the resin layer. How to define the reference line and how to determine uneven distribution will be described later. For example, when observing the cross section of the electrode substrate, the resin substrate, unevenly distributed second solid electrolyte particles, active material particles, and first solid electrolyte particles are arranged in this order from the lower side of the electrode substrate (the side on which the particle layer is not formed). Alternatively, the resin substrate, active material particles, first solid electrolyte particles, and unevenly distributed second solid electrolyte particles may be arranged in this order from the lower side of the electrode substrate (the side on which the particle layer is not formed). That is, in the particle layer in the electrode substrate, a dense portion of the solid electrolyte particles is provided on the side in contact with the resin substrate or on the side opposite the resin substrate side, and a uniform void portion is provided on the side opposite the dense portion. By adopting such a configuration, the influence of volume fluctuation of the active material particles can be mitigated. Preferably, 80% or more of the second solid electrolyte particles are unevenly distributed on the side opposite the resin substrate side.

[0033] For example, third particles P3, which may correspond to second solid electrolyte particles, are disposed on a resin substrate, which is a material for the electrode substrate, by a method described below. This allows the second solid electrolyte particles to be controlled so as to be unevenly distributed in the electrode substrate. In the present disclosure, the second solid electrolyte particles present on the resin substrate are identified in the electrode substrate, and if 80% or more by number of the identified particles are present on the side in contact with the resin substrate or on the side opposite the resin substrate, the second solid electrolyte particles are determined to be unevenly distributed. Methods for identifying second solid electrolyte particles and determining uneven distribution will be described later.

[0034] The average equivalent circular diameter ra of the active material particles is defined as the cumulative 50% particle diameter (by number) calculated from the distribution of equivalent circular diameters of the primary particles of the active material particles. The average equivalent circular diameter re of the solid electrolyte particles is defined as the cumulative 50% particle diameter (by number) calculated from the distribution of equivalent circular diameters of the primary particles of the solid electrolyte particles. In this case, the ratio of the average equivalent circular diameter re to the average equivalent circular diameter ra (re / ra) is 0.01 or more and 2.0 or less.

[0035] Active material particles often have higher electronic conductivity than solid electrolyte particles, and the degree of contact between active material particles is likely to affect the electronic conductivity within the electrode. A re / ra ratio of 0.01 or greater indicates that the average equivalent circular diameter re of the primary particles of the solid electrolyte particles is appropriately larger than the average equivalent circular diameter ra of the active material particles. As a result, the cohesive force and adhesive force of the solid electrolyte particles can be controlled within an appropriate range. By controlling the cohesive force of the solid electrolyte particles within an appropriate range where it is not excessive, it becomes easier to mix them appropriately when stirred with the support described below. Furthermore, by controlling the adhesive force within an appropriate range where it is not excessive, it is possible to prevent the solid electrolyte particles from covering the upper part of the active material particles arranged on the electrode substrate. Therefore, contact between the active material particles is not hindered, and high electronic conductivity within the electrode is maintained.

[0036] A re / ra of 2.0 or less indicates that the average equivalent circle diameter re of the primary particles of the solid electrolyte particles is not excessively large relative to the average equivalent circle diameter ra of the active material particles and is within an appropriate range. As a result, a larger number of active material particles can be arranged on the electrode substrate without impeding contact between the active material particles. As described above, the solid electrolyte particles and the active material particles are arranged on a resin substrate. A re / ra of 2.0 or less reduces the unevenness of the substrate surface. Therefore, when the electrode substrates are stacked by the method described below, sufficient contact can be achieved between the active material particles and the solid electrolyte particles, or between the active material particles themselves, in the substrate stacking direction without being impeded. This allows the ionic conductivity of the battery to be maintained high and the rate characteristics to be improved. Furthermore, since a larger number of active material particles can be arranged on the electrode substrate, a battery with a high volumetric energy density can be manufactured.

[0037] re / ra is preferably 0.05 or more, more preferably 0.10 or more, and even more preferably 0.50 or more. It is also preferably 1.8 or less, more preferably 1.5 or less, and even more preferably 1.0 or less. For example, it is preferably in the range of 0.05 to 1.8, 0.10 to 1.5, or 0.50 to 1.0.

[0038] Although ra is not particularly limited, it is preferably 0.1 to 100 μm, more preferably 0.5 to 20 μm, and even more preferably 1 to 10 μm. Although re is not particularly limited, it is preferably 0.01 to 50 μm, more preferably 0.05 to 10 μm, and even more preferably 0.1 to 5 μm.

[0039] <Method for manufacturing electrode substrate> An example of a method for manufacturing an electrode substrate will be described in detail below with reference to the drawings. Hereinafter, a positive electrode substrate using positive electrode active material particles will be described as an example, but the manufacturing method described below can be used as a method for manufacturing an electrode substrate for both positive and negative electrodes.

[0040] The manufacturing method of the electrode substrate includes the following steps: (1) a preparation step of preparing a resin substrate having an adhesive portion; (2) a first step of arranging first particles P1 on the surface of the adhesive portion (S101 in FIG. 1); (3) a second step of arranging second particles P2 on the surface of the adhesive portion (S102 in FIG. 1); (4) a third step of settling the first particles P1 and the second particles P2 into the adhesive portion (S103 in FIG. 1); and (5) a fourth step of arranging third particles P3 in contact with the settled first particles P1 or second particles P2, the third particles P3 having an average equivalent circular diameter smaller than the first particles P1 and the second particles P2 (S104 in FIG. 1).

[0041] (Preparation Step) In the preparation step, a resin substrate having an adhesive portion is prepared. In the present disclosure, "having an adhesive portion" means that an adhesive portion is provided on a part or the entire surface of the resin substrate. As the resin substrate, a substrate containing the above-mentioned resin can be used. Although there is no particular limitation on the method for providing the adhesive portion, a method of applying an adhesive to the surface of the resin substrate is preferred. The adhesive is not particularly limited, and known adhesives can be used. For example, it may be an acrylic adhesive, a rubber adhesive, or a silicone adhesive, or it may be a thermoplastic resin or a photocurable resin whose adhesive strength changes in response to external disturbances such as heat or light.

[0042] (First Step and Second Step) The first step is a step of arranging first particles P1 on the surface of the adhesive portion of the resin substrate. The second step is a step of arranging second particles P2 on the surface of the adhesive portion of the resin substrate. Note that, although the second step (S102) is illustrated in FIG. 1 as following the first step (S101), the order of the first step and the second step is not particularly limited. In other words, the step of arranging first particles P1 may be performed after the step of arranging second particles P2 on the surface of the adhesive portion.

[0043] The first particles P1 are active material particles. For example, the above-described active material particles can be used as the first particles P1. The particle size of the primary particles of the first particles P1 is not particularly limited, but for example, the cumulative 10% particle size (r10) in the volume-based particle size distribution is preferably 0.1 to 10.0 μm, and more preferably 1.0 to 7.0 μm. Furthermore, the cumulative 50% particle size (r50) in the volume-based particle size distribution is preferably 0.5 to 20.0 μm, and more preferably 2.0 to 10.0 μm. Furthermore, the cumulative 90% particle size (r90) in the volume-based particle size distribution is preferably 2.0 to 20.0 μm, and more preferably 3.0 to 15.0 μm.

[0044] The second particles P2 are solid electrolyte particles that can correspond to the first solid electrolyte particles in the electrode substrate. The above-described materials can be used as the solid electrolyte particles. The cumulative 50% particle size (r50) of the primary particles of the second particles P2 in the volume-based particle size distribution is larger than the r50 of the primary particles of the third particles P3 described below.

[0045] The particle size of the primary particles of the second particles P2 is not particularly limited as long as it is larger than that of the third particles P3. For example, the second particles P2 preferably have a cumulative 10% particle size (r10) in the volume-based particle size distribution of the primary particles of 0.5 to 10.0 μm, more preferably 1.0 to 7.0 μm. Furthermore, the cumulative 50% particle size (r50) in the volume-based particle size distribution is preferably 1.0 to 20.0 μm, more preferably 5.0 to 15.0 μm. Furthermore, the cumulative 90% particle size (r90) in the volume-based particle size distribution is preferably 5.0 to 50.0 μm, more preferably 10.0 to 30.0 μm.

[0046] The ratio of the particle size of the primary particles of the first particles P1 to the particle size of the primary particles of the second particles P2 is not particularly limited. For example, the ratio {(r50(P1)) / (r50(P2))} of the cumulative 50% particle size (r50(P2)) in the volume-based particle size distribution of the primary particles of the first particles P1 to the cumulative 50% particle size (r50(P2)) in the volume-based particle size distribution of the primary particles of the second particles P2 is preferably 0.05 to 20.0, and more preferably 0.1 to 2.0.

[0047] As described above, the first particles P1 are active material particles. The second particles P2 are particles that can correspond to the first solid electrolyte particles in the manufactured electrode substrate. That is, in the manufacturing method of the electrode substrate, the first and second steps can be described as steps of arranging the active material particles and the first solid electrolyte particles on the surface of the adhesive portion. In the first and second steps, particles are arranged on the adhesive portion of the resin substrate using a particle arrangement device. Hereinafter, particle arrangement device 1 and particle arrangement device 2 that can be used will be described in order.

[0048] 2 is a diagram schematically illustrating the configuration of the particle arrangement device 1. The particle arrangement device 1 includes a first storage container 21a that stores and supplies the first substrate 11a, a first belt device 22a that transports the first substrate 11a, and a pattern forming device 23 that forms a concave-convex pattern on the first substrate 11a. The particle arrangement device 1 also includes a first filling device 24a that arranges first particles P1 in recesses of the concave-convex pattern formed on the first substrate 11a. The particle arrangement device 1 also includes a second storage container 21b that stores and supplies the second substrate 11b, and a second belt device 22b that transports the second substrate 11b. The particle placement device 1 has a transfer section 25a in which rollers 223 respectively possessed by a first belt device 22a and a second belt device 22b face each other, and in the transfer section 25a, a first particle P1 is transferred from a first substrate 11a to a second substrate 11b.

[0049] Furthermore, the particle placement device 1 has a second filling device 24b that places second particles P2 in the non-transfer portion on the second substrate 11b. Note that devices that are less relevant to explaining the effects of the present invention, such as a peeling and recovery device that peels and recovers the first substrate 11a from the first belt device 22a after transfer and various cleaning devices, will not be shown in the drawings or described in detail.

[0050] In the particle placement device 1, the pattern forming device 23, the first filling device 24a, and the transfer unit 25a correspond to a first placement unit that places the first particles P1 in a pattern on the second substrate 11b. The second filling device 24b corresponds to a second placement unit that places the second particles P2 in areas on the second substrate 11b where the first particles P1 are not placed.

[0051] Below, the method for arranging particles on the substrate 11 using the particle arrangement device 1 will be described along the flow of each process. First, the first substrate 11a is supplied from the first storage container 21a to the first belt device 22a by a supply means (not shown). When a UV-curable liquid is applied by the pattern formation device 23 (described later), it is preferable that at least the surface of the first substrate 11a be made of a material that is highly wettable by the UV-curable liquid. It is also preferable that the surface of the first substrate 11a be smooth.

[0052] The first substrate 11a may be a sheet made of a resin such as polyester that has been subjected to a hydrophilic or lipophilic treatment in accordance with the ultraviolet-curable liquid (water-based or oil-based) to be used. The first substrate 11a may be a substrate that is individually cut out like cut paper, a continuous substrate wound into a roll like roll paper, or a continuous substrate that is alternately folded like continuous paper.

[0053] The first belt device 22a transports the supplied first substrate 11a to a pattern formation position of the pattern forming device 23. The first belt device 22a has drive rollers 221a and 222a, a pressure roller 223a, and a belt-like transport member 224a suspended between them. At this time, the pressure roller 223a is rotated by being driven.

[0054] The conveying member 224a is preferably made of a material selected from resin or metal, such as a polyimide resin belt. The drive rollers 221a and 222a are preferably made of metal, such as stainless steel rollers. The pressure roller 223a is preferably a soft roller having an elastic layer on its surface, such as a soft roller having a silicone rubber elastic layer on the surface of a stainless steel core.

[0055] 2, the first belt device 22a is used as a conveying device for conveying the first base material 11a, but a roller device may be used instead of the belt device. The same applies to the second belt device 22b described later.

[0056] The pattern forming device 23 forms a fine concave-convex pattern on the first substrate 11a that has been transported to the pattern forming position. Methods for forming the concave-convex pattern include UV imprinting, thermal imprinting, UV inkjet printing, printing, and laser etching.

[0057] When the pattern forming device 23 forms a concave-convex pattern using a UV imprinting method, the pattern forming device 23 has a coating means for coating a UV-curable liquid onto the first substrate 11a. The UV-curable liquid can be, for example, a UV-curable resin such as UV-curable liquid silicone rubber. The pattern forming device 23 also has an imprinting means for imprinting a mold having a concave-convex pattern formed on its surface onto the UV-curable liquid on the first substrate 11a, and a light source for irradiating the UV-curable liquid with UV rays. Typically, UV-curable liquid silicone rubber (PDMS) or resin is used as the UV-curable liquid, a film mold is used as the mold, and a UV lamp is used as the light source.

[0058] When the first filling device 24a fills the recesses on the first substrate 11a with the first particles P1 using the support material S1 carrying the first particles P1, the opening diameter (width) of the recesses in the concave-convex pattern on the first substrate 11a is preferably larger than the cumulative 50% particle diameter (median diameter) of the first particles P1 on a volume basis. Furthermore, the opening diameter (width) of the recesses is preferably smaller than the average size of the support material S1. Here, the opening diameter of the recesses in the concave-convex pattern is preferably the opening diameter in the short-side direction of the recesses, and more preferably the maximum opening diameter in the short-side direction of the recesses. The width of the recesses can be adjusted appropriately depending on the particle diameters of the first particles P1 and the support material S1. The width of the recesses is not particularly limited, but is preferably 0.2 to 30 μm, and more preferably 2 to 15 μm.

[0059] By setting the opening diameter of the recesses of the concave-convex pattern as described above, the first particles P1 can contact the bottoms and side surfaces (typically the bottom surfaces) of the recesses of the concave-convex pattern. On the other hand, the support material S1 cannot contact the bottoms and side surfaces of the recesses. This allows the first particles P1 that contact the bottoms and side surfaces of the recesses to be captured by the concave-convex pattern, while preventing the support material S1 from being captured by the concave-convex pattern. In other words, it is preferable that the first particles P1 can contact the bottoms and side surfaces of the recesses of the concave-convex pattern, and that the first support material S1 cannot contact the bottoms and side surfaces of the recesses of the concave-convex pattern.

[0060] Although the pattern forming device 23 forms a concave-convex pattern on the first substrate 11a, a substrate with a concave-convex pattern pre-formed on its surface may be used as the first substrate 11a. Alternatively, the pattern forming device 23 may form a concave-convex pattern directly on the surface of the conveying member 224a of the first belt device 22a, or a conveying member having a concave-convex pattern on its surface may be used as the conveying member 224a. In this case, in consideration of durability, it is preferable to use a metal belt made of stainless steel, aluminum, or the like, and form the concave-convex pattern on the surface by a micromachining technique such as laser etching, wet etching, or dry etching.

[0061] The first base material 11a having the concave-convex pattern formed on its surface is transported by the first belt device 22a to the filling position of the first filling device 24a. Fig. 3 is a diagram showing a schematic configuration of the filling device. The configuration of the first filling device 24a will be described below, but the same applies to the second filling device 24b.

[0062] The first filling device 24a has a filling container 242a that stores a filler 241a, a stirring screw member 243a that stirs and conveys the filler 241a, a recovery member 244a that recovers the filler, and a magnetic member 247a.

[0063] The filler 241a includes first particles P1 and a support material S1 that supports the first particles P1. The filler 241a is a mixture of multiple powders, including a powder composed of multiple first particles P1 and a powder composed of multiple support materials S1. The filler 241a contained in the filling container 242a is thoroughly mixed when stirred and transported by the stirring screw member 243a. As a result, the first particles P1 are supported on the surface of the support material S1. The forces acting between the particles when supported include electrostatic forces due to frictional charging and the like, as well as van der Waals forces and liquid bridging forces.

[0064] The support material S1 is a magnetic particle. The support material S1 is preferably a particle in which the surface of a resin particle in which ferrite core particles or a magnetic material is dispersed is coated with a resin composition. For example, a standard carrier (Standard Carrier P02 manufactured by the Japan Imaging Society), which is a magnetic particle, can be used. The particle size and material of the support material S1 are appropriately selected according to the particle size and material of the first particles P1. This allows the first particles P1 to be stably supported. Furthermore, even if the first particles P1 are small in particle size and prone to agglomeration, the support material S1 plays a role in loosening the particles by stirring and transporting them with the support material S1. The particle size of the support material S1 can be appropriately adjusted by the size (area, width, depth) of the recess. For example, the cumulative 50% particle size (median diameter) based on volume is preferably 50 to 100 μm.

[0065] Recovery member 244a has roller 245a that can rotate in the direction of arrow d2 in the figure, and magnet 246a that is arranged inside roller 245a and fixed to filling container 242a. Magnetic member 247a is arranged opposite filling container 242a across transport member 224a, and has magnet 248a inside.

[0066] The magnet 246a has multiple north and south poles arranged alternately along the rotation direction of the recovery member 244a. The magnet 248a has multiple north and south poles arranged alternately along the transport direction of the transport member 224a. Furthermore, the magnet 246a has a magnetic pole (N1 pole in FIG. 3 ) of opposite polarity at the position closest to and facing the most downstream magnetic pole (S1 pole in FIG. 3 ) of the magnet 248a, and an N2 pole of the same polarity as the N1 pole is arranged at the most downstream position. The magnets 246a and 248a may be composed of multiple magnets, and the type of magnets constituting the magnets 246a and 248a is not particularly limited. For example, permanent magnets such as ferrite magnets, neodymium magnets, and rare earth magnets such as samarium-cobalt magnets, plastic magnets, or magnetic field generating means such as electromagnets can be used. The magnet 248a may be configured to be movable in the transport direction of the first substrate 11a or in the opposite direction.

[0067] Note that a regulating member for regulating the filler 241 a on the first base material 11 a or a collecting member for re-collecting the filler 241 a that cannot be collected by the collecting member 244 a may be provided upstream or downstream of the collecting member 244 a in the transport direction of the transport member 224 a. The collecting member for re-collecting the filler 241 a may be a member similar to the collecting member 244 a, or may be a simple member such as a fixed magnet or a regulating member, or a collecting member that performs collection by air blowing.

[0068] Next, the process of filling the recesses on the first substrate 11a with the first particles P1 by the first filling device 24a will be described with reference to Figures 3 to 5. The first substrate 11a carried and transported by the first transport member 224a is transported to the loading position of the first filling device 24a by the first transport member 224a moving in the direction of the solid arrow d1 in Figure 3.

[0069] The filler 241a is transported by the stirring screw member 243a and supplied onto the first substrate 11a (dotted line a in FIG. 3). At this time, a magnetic field is formed by the magnetic member 247a and the recovery member 244a, and the filler 241a containing the magnetic particle carrier material S1 forms multiple magnetic chains on the first substrate 11a due to the magnetic field. The filler 241a supplied onto the first substrate 11a is transported on the first substrate 11a while forming magnetic chains as the first substrate 11a moves (dotted line b in FIG. 3).

[0070] Figures 4A, 4B, and 4C are schematic diagrams of filler 241a being transported on the first substrate 11a. For illustrative purposes, filler 241a other than the filler forming a single magnetic strand are omitted from the illustration. As described above, the filler 241a on the first substrate 11a forms magnetic strands along the magnetic field lines of the generated magnetic field. As the first substrate 11a moves, the magnetic strands change shape as they are transported, as shown in Figures 4A, 4B, and 4C. Because a particularly strong magnetic force acts near the magnet 248a, the transport speed v2 of the filler 241a is smaller than the movement speed v1 of the first substrate 11a when the filler 241a moves away from the magnetic pole, and is larger when the filler 241a moves away from the magnetic pole. In other words, the filler 241a on the first substrate 11a has a non-zero relative speed with respect to the first substrate 11a.

[0071] FIG. 5 is an enlarged view of the surface vicinity of the first substrate 11a in FIGS. 4A-C. Although not shown in FIGS. 4A-C, a concave-convex pattern 111a is formed on the first substrate 11a as shown in FIG. 5. The concave-convex pattern can be formed as desired, such as a honeycomb pattern or a line pattern. The filler 241a contacts the concave-convex pattern 111a and is transported together with the first substrate 11a at a non-zero relative speed relative to the first substrate 11a while being subjected to a magnetic force (solid line Fm in the figure) perpendicular to the surface of the first substrate 11a. As a result, the first particles P1 supported on the support material S1 are transported while being rubbed against the concave-convex pattern 111a on the surface of the first substrate 11a.

[0072] At this time, the particle size of the first particles P1 is smaller than the opening diameter of the recesses of the uneven pattern 111a, and the particle size of the first support material S1 is larger than the opening diameter of the recesses, so the first particles P1 can contact the bottom surfaces (bottoms) and side surfaces of the recesses of the uneven pattern 111a, but the support material S1 cannot. In other words, only the first particles P1 in the filler 241a selectively contact the bottom surfaces and side surfaces of the recesses.

[0073] The first particles P1 that come into contact with the recesses are strongly restrained by the physical restraining force due to the structure of the concave-convex pattern 111a and by non-electrostatic adhesive forces such as electrostatic adhesive forces and adhesive forces with the structural materials that make up the first base material 11a and the concave-convex pattern 111a, and are detached from the support material S1. Note that, for the sake of explanation, in Fig. 5, the first particles P1 are supported on the surface of the support material S1, but it is acceptable for there to be first particles P1 that are not supported on the support material S1 during the agitation, supply, or transport of the filler 241a.

[0074] As shown in Fig. 3, downstream of the magnetic member 247a, a recovery member 244a is disposed with a gap between it and the first transport member 224a. As the first base material 11a moves, the filler 241a is transported to the vicinity of the most downstream magnetic pole (pole S1) of the magnet 248a. Under the influence of the magnetic field formed by the magnet 246a, the filler 241a moves from the first base material 11a to the recovery member 244a and is recovered (dotted line c in Fig. 3).

[0075] As described above, during the transport process (dotted lines a, b, and c in FIG. 3), the recesses of the concave-convex pattern 111a on the surface of the first base material 11a are in sufficient contact with the plurality of fillers 241a. Therefore, after the fillers 241a are collected by the collection member 244a, the first particles P1 are selectively and densely arranged in the recesses of the concave-convex pattern 111a.

[0076] 4A to 4C and 5, the first particles P1 are all shown with the same particle size, but in reality there is a particle size distribution, and depending on the material, the particles may form aggregated secondary particles. Furthermore, the particles may not have the spherical shape shown in the figure. Even in such cases, only particles that can contact the recesses of the concave-convex pattern 111a are selectively and densely packed, so that coarse powder and secondary particles that may adversely affect the particle placement process are easily excluded.

[0077] In this way, the amount of the first particles P1 filling the recesses of the concave-convex pattern 111a can be controlled by the size (area, width, height) of the concave-convex pattern and the particle size of the first particles P1. Specifically, the area of ​​the recesses is approximately the filling area, and the layer thickness of the filled first particles P1 is determined by the height of the convex portions. The pitch of the convex portions is not particularly limited, but is preferably, for example, 1.0 to 20 μm, and more preferably 2.0 to 15 μm. The height of the convex portions is not particularly limited, but is preferably, for example, 0.1 to 20.0 μm, and more preferably 1.0 to 10.0 μm. The area ratio of the concave portions (the ratio of the concave portions to the area of ​​the concave-convex pattern) is not particularly limited, but is preferably, for example, 50% or more, and more preferably 70% or more.

[0078] For example, to obtain a thin layer (single layer) that accounts for 50% of the area of ​​the substrate, the area ratio of the recesses (the area ratio of the recesses to the entire concave-convex pattern) should be 50%, and the depth of the recesses should be equal to or less than the particle size of the first particles P1. In this case, the opening width of the recesses should be larger than the median diameter of the first particles P1 and smaller than the average size (here, the average particle size) of the support material S1.

[0079] Although the first particles P1 may have a wide particle size distribution (broad particle size distribution), the support material S1 preferably has a narrow particle size distribution, and is more preferably monodisperse. This makes it easier to prevent the support material S1 from contacting the bottom (or bottom surface) or side surface of the recess. If the support material S1 can contact the bottom or side surface of the recess, there is a risk that the support material S1 will also be restrained and filled into the recess.

[0080] Furthermore, the opening width of the recesses of the uneven pattern 111a is preferably smaller than four times the particle diameter of the first particles P1. By making the opening width smaller than four times the particle diameter of the first particles P1, the probability that the first particles P1 will contact two points, the bottom and side surfaces of the recesses of the uneven pattern 111a, can be increased. In this way, the first particles P1 that make multiple contacts with the recesses of the uneven pattern 111a are strongly constrained by the uneven pattern 111a, thereby increasing the efficiency of filling the uneven pattern 111a with the first particles P1. The same applies to the particle diameter of the second particles P2 (described later) and the size of the recesses of the uneven pattern formed by the first particles P1 on the second substrate. Furthermore, when brush fibers are used as the carrier material, the "average particle diameter of the carrier material" in the above description becomes the "average fiber diameter of the carrier material."

[0081] The filler 241a collected by the collecting member 244a is transported by the rotating collecting member, roller 244a (dotted line d in FIG. 3). The filler 241a transported by roller 244a falls into filling container 242a (dotted line e in FIG. 3) due to the magnetic field generated by two adjacent, repelling magnetic poles of the same polarity (N1, N2) and the influence of gravity. Thereafter, the filler 241a is again stirred and transported by stirring screw member 243a, and this process is repeated thereafter.

[0082] The mass ratio of the first particles P1 to the support material S1 in the filler 241a in the filling container 242a is determined by an inductance sensor that measures magnetic permeability, a patch density sensor that measures and predicts the reflection density on a substrate, or the like, which are common in electrophotographic devices. At least one of the first particles P1 and the support material S1 is replenished by a replenishment means (not shown) as needed. This allows stable filling over a long period of time.

[0083] The mass % of the first particles P1 in the filler 241a (the ratio of the mass of the first particles P1 to the total mass of the filler 241a) is expressed by the following formula (1) using the coverage S1 of the supported first particles P1 to the surface area of ​​the magnetic particles (support material). The coverage S1 indicates the ratio of the total cross-sectional area of ​​the first particles P1 to the surface area of ​​the magnetic particles (support material). Mass % of the first particles P1 in the filler 241a = (400 × ρＰ１ ×r Ｐ１ × S1) / (100 × ρ ｃ ×r ｃ +4×ρ Ｐ１ ×r Ｐ１ ×S1) Equation (1) (The symbols in equation (1) represent the following: ρ Ｐ１ : true density of the first particle P1, r Ｐ１ : particle size (r50) of the first particle P1, ρ ｃ : true density of magnetic particles, r ｃ : particle size of the magnetic particle (r50), S1: coverage rate of the first particle P1 relative to the surface area of ​​the magnetic particle)

[0084] The mass % of the first particles P1 in the filler 241a is not particularly limited, but is preferably in the range of 5 to 40 mass %, or 10 to 30 mass %. Furthermore, the coverage S1 in the above formula (1) is preferably adjusted to 30 to 200 area %, and more preferably adjusted to 50 to 100 area %. The particle diameters (r50) of the first particles P1 and the magnetic particles (support material) can be determined by laser diffraction / scattering particle size distribution measurement. Furthermore, the true density of the first particles P1 and the magnetic particles (support material) can be determined by a pycnometer method.

[0085] Although the filling device described here uses magnetic particles as a carrier material to form a magnetic brush, filling the recesses with the particulate material, the filling device method is not limited to this. Brush fibers can also be used as the carrier material. Alternatively, an elastic material, at least the surface of which is made of an elastic body, can also be used as the carrier material.

[0086] 6A is a diagram schematically illustrating the configuration of a filling device 24c when brush fibers are used as the carrier material. The filling device 24c has a roller 2410 with brush fibers on its surface. The roller 2410 is a so-called brush roller, with brush fibers planted on its surface. The brush fibers of the roller 2410 may be made of, for example, nylon, rayon, acrylic, vinylon, polyester, or vinyl chloride. The surface of the fiber may be subjected to a surface treatment in order to adjust the chargeability or rigidity.

[0087] The filling device 24c has a supply member that supplies the filler 241a to the roller 2410. The filler 241a contains powder including the first particles P1 and is stored in a filling container 242a. In this example, the filler 241a does not contain the carrier material S1, which is a magnetic particle. The filler 241a is stirred and transported by a stirring screw member 243a and supplied to a supply member 249.

[0088] The supply member 249 supplies the filler 241a to the roller 2410, and its configuration is not particularly limited. For example, the supply member 249 can be a roller whose surface is made of an elastic, porous foam material. Typically, an elastic sponge roller having a foamed skeleton structure and a relatively low-hardness polyurethane foam formed on a core metal can be used. Note that, in addition to urethane, various rubber materials such as nitrile rubber, silicone rubber, acrylic rubber, hydrin rubber, and ethylene propylene rubber can be used as the foam material.

[0089] The supplied filler 241a is filled into the foam material on the surface of the supply member 249 and is transported to a supply section that comes into contact with the roller 2410. In the supply section, the filler 241a filled into the foam material is charged by contact with the brush fibers of the roller 2410 and is carried by the brush fibers of the roller 2410. Furthermore, the supply member 249 may also have a function of stripping off and refreshing the filler 241a remaining on the roller 2410. The filler 241a supplied to the roller 2410 comes into contact with the first substrate 11a as the brush fibers move.

[0090] At this time, the first particles P1 in the filler 241a can contact the bottom and side surfaces of the recesses of the uneven pattern 111a on the surface of the first substrate 11a, but the brush fibers cannot. That is, the fiber diameter of the brush fibers is set to be larger than the opening width of the recesses of the uneven pattern 111a. The fiber diameter of the brush fibers can be measured by placing glass on the surface of the roller 2410 and taking an image of the brush fibers through the glass using an optical microscope. At this time, the fiber diameters of approximately 100 brush fibers are measured, the fiber diameter distribution is measured, and the average diameter is calculated.

[0091] The movement of the transport member 224a and the rotation of the roller 2410 cause the brush fibers of the roller 2410 to rub against the surface of the first substrate 11a, so that the first particles carried by the brush fibers are densely arranged in the recesses of the uneven pattern 111a on the surface of the first substrate 11a.

[0092] 6B is a diagram showing a schematic configuration of a filling device 24d when an elastic material is used as the carrier material. The filling device 24d has a similar configuration to the filling device 24c, but differs in that a roller 2411 having an elastic material is used instead of the roller 2410 having brush fibers. The roller 2411 is a roller having an elastic layer formed on its surface.

[0093] The elastic layer is formed of an elastic material such as a rubber material, such as silicone rubber, acrylic rubber, nitrile rubber, urethane rubber, or fluororubber. The surface shape of the elastic layer may be controlled by adding spherical resin particles or other fine particles. If the elastic layer has convex portions on its surface, the size of the convex portions of the elastic layer is set larger than the size of the concave portions of the concave-convex pattern 111a. The size of the convex portions of the elastic layer can be measured in the same manner as the fiber diameter of the brush fibers described above.

[0094] The movement of the transport member 224a and the rotation of the roller 2411 causes the elastic material on the surface of the roller 2411 to rub against the surface of the first base material 11a, thereby causing the first particles carried by the elastic material to be densely arranged in the recesses of the concave-convex pattern 111a on the surface of the first base material 11a.

[0095] By using brush fibers or elastic material as the carrier material as shown in Figures 6A and 6B, it is not necessary to include magnetic particles in the filler. Furthermore, the configuration of the filling device can be simplified. On the other hand, when magnetic particles are used as the carrier material as shown in Figure 3, there is greater freedom in the size and shape of the carrier material than when using brush fibers or elastic material. Furthermore, magnetic particles allow greater freedom in the movement of the carrier material on the substrate.

[0096] For these reasons, when magnetic particles are used as the support material, particles such as the first particles P1 can be more efficiently supplied onto the substrate, and recesses on the substrate can be more efficiently filled. Also, when a magnetic material is used as the support material, even if the support material deteriorates during the process, it can be replenished or replaced without stopping the process.

[0097] The method of filling the recesses with particles by rubbing a support material carrying the particles allows a larger amount of dispersed particles to be supplied to the recesses, and allows for stable and dense filling, compared to a filling method using a restricting member such as a blade. This advantage is more pronounced as the particle size of the particles to be filled becomes smaller, since the particles tend to aggregate more easily.

[0098] The first substrate 11a, in which the recesses of the concave-convex pattern 111a have been filled with the first particles P1 by the first filling device 24a, is transported to the transfer unit 25a by the first belt device 22a. Here, the second belt device 22b, like the first belt device 22a, has drive rollers 221b and 222b, a pressure roller 223b, and a belt-like transport member 224b suspended therebetween, as shown in FIG. 2. At this time, the pressure roller 223b is driven to rotate. In the transfer unit 25a, the pressure roller 223a of the first belt device 22a and the pressure roller 223b of the second belt device 22b face each other.

[0099] The second substrate 11b is supplied from the second storage container 21b to the second belt device 22b and transported in the direction of the arrow in Fig. 2. The supplied second substrate 11b is transported in synchronization with the transport of the first substrate 11a to the transfer unit 25a. In the transfer unit 25a, the first particles P1 filled in the first substrate 11a are transferred to the second substrate 11b.

[0100] That is, the first substrate 11a can also be referred to as a transfer substrate for transferring the first particles P1 to the second substrate 11b. The concave-convex pattern formed on the surface of the first substrate 11a can also be referred to as a transfer concave-convex pattern. This transfer process will be described below with reference to FIG. 7.

[0101] 7 is a diagram showing a schematic configuration of the transfer unit 25a. The transfer unit 25a is composed of the pressure roller 223a and the conveying member 224a of the first belt device 22a, and the pressure roller 223b and the conveying member 224b of the second belt device 22b. As described above, the pressure rollers 223a and 223b rotate drivenly, and the two rollers are in contact with each other via the conveying members 224a and 224b. At least one of the pressure rollers 223a and 223b is a soft roller having an elastic layer on its surface, and a nip is formed where the two rollers contact each other.

[0102] The first substrate 11a and the second substrate 11b, which have been filled with the first particles P1 by the first filling device 24a, are transported at approximately the same speed by their respective transport members (224a and 224b) and enter a nip formed by contact between the pressure rollers 223a and 223b. In the nip, the first particles P1 on the first substrate 11a come into contact with the second substrate 11b and are transferred onto the second substrate 11b.

[0103] The second substrate 11b has a stronger adhesive force to the first particles P1 than the first substrate 11a has to the first particles P1. In other words, the adhesive force of the first particles P1 to the second substrate 11b is stronger than the adhesive force of the first particles P1 to the first substrate 11a. As a result, the first particles P1 on the first substrate 11a are transferred to the second substrate 11b at the nip portion.

[0104] The material of the second substrate 11b is not particularly limited, and a substrate of the same material as the first substrate 11a can be used. Note that, like the first substrate 11a, the second substrate 11b may be a substrate that is individually cut like cut paper, a continuous substrate that is wound into a roll like roll paper, or a continuous substrate that is alternately folded like continuous paper.

[0105] The second substrate 11b is preferably subjected to a surface treatment to enhance adhesive strength in order to transfer the contacted first particles P1. For example, the second substrate 11b preferably has an adhesive portion on its surface where an adhesive is applied. As a preparation step for preparing a resin substrate having an adhesive portion, for example, the second substrate 11b is prepared. The thickness of the second substrate is not particularly limited, but is preferably, for example, 1 to 10 μm. Furthermore, the thickness of the adhesive portion is not particularly limited, but is preferably, for example, 0.1 μm or more, and more preferably 0.5 μm or more.

[0106] Furthermore, it is preferable that the back surface of the second substrate 11b (the surface to which the first particles P1 are not transferred) also has an adhesive portion coated with the same adhesive as the front surface, and that the front surface is further covered with a protective film, etc. This prevents the substrates from shifting when stacked as described below, and also sandwiches and firmly fixes the active material particles and solid electrolyte particles between the substrates between the upper and lower surfaces (stacking direction).As a result, particle movement is suppressed when stacking the electrode substrates, storing the stack, heat treating, or applying pressure, and a desired electrode can be formed.

[0107] The adhesive is not particularly limited, and the adhesives described above can be used. The particle placement device 1 may also have an application means, such as a dispenser, inkjet head, spin coater, or bar coater, that applies the adhesive to the surface of the second substrate 11b during transport. The type and amount of adhesive applied are adjusted appropriately depending on the shape and material of the concave-convex pattern used, the particle size and material of the first particles P1 and the second particles P2, and the like, but it is preferable that the adhesive has a greater adhesive strength than the concave-convex pattern 111a. Comparison of adhesive strength can be measured by a common method using a nanoindenter.

[0108] At the nip portion, the first particles P1 are restrained by the adhesive force generated between the first particles P1 and the second substrate 11b. When the conveying members 224a and 224b pass through the nip portion and are separated from each other, the first particles P1 on the first substrate 11a are transferred to the second substrate 11b.

[0109] The second substrate 11b onto which the first particles P1 have been transferred is transported by a transport member 224b to a filling position of a second filling device 24b. The second filling device 24b has the same configuration and function as the first filling device 24a, except that a filling container 242a contains a filler 241b having second particles P2 and a carrier material S2 instead of the filler 241a having the first particles P1 and a carrier material S1.

[0110] The second filling device 24b fills the second particles P2 into the portions of the second substrate 11b where the first particles P1 are not placed. As described above, the first particles P1 are placed on the second substrate 11b that has passed through the transfer unit 25a, but the adhesive portions are exposed in the portions where the first particles P1 are not placed, forming recesses, so to speak. The second filling device 24b fills the recesses (adhesive portions) with the second particles P2 using the same process as the first filling device 24a.

[0111] In this way, the second particles P2 that can be filled are selectively filled into the gaps on the second substrate 11b where the first particles P1 are not placed, thereby improving the coverage of the substrate by the particles. The second particles P2 preferably have a median diameter equal to or smaller than the opening width of the gaps between the first particles P1. Note that, although the case where magnetic particles are used as the carrier material will be described here, brush fibers or elastic materials may also be used as the carrier material, as in the first filling device 24a.

[0112] The filler 241b includes second particles P2 and a support material S2 that supports the second particles P2. The filler 241b is a mixture of multiple powders including a powder composed of multiple second particles P2 and a powder composed of multiple support materials S2. The support material S2 may be the same as or different from the support material S1. The support material S2 is selected appropriately depending on the particle size and material of the second particles P2 and the opening width of the voids described above.

[0113] FIG. 8 is an enlarged view of the surface of the second substrate 11b during the filling process using the second filling device 24b. A concave-convex pattern is formed on the second substrate 11b, including protrusions formed by the first particles P1 and recesses where the first particles P1 are not disposed. The adhesive portions 13b are exposed in the recesses on the second substrate 11b where the first particles P1 are not disposed. During the filling process using the second filling device 24b, the second particles P2 are disposed on the adhesive portions 13b on the surface of the second substrate 11b. After the filling process using the second filling device 24b, the first particles P1 and the second particles P2 are disposed adjacent to each other on the surface of the adhesive portion of the second substrate 11b. That is, by disposing the second particles P2 in the portions of the second substrate 11b where the first particles P1 are not disposed, the first particles P1 and the second particles P2 can be disposed adjacent to each other. Furthermore, it is not necessary that the second particles P2 are disposed adjacent to all of the first particles P1, and the first particles P1 or the second particles P2 may be adjacent to each other.

[0114] The filler 241b comes into contact with this uneven pattern and is transported together with the second substrate 11b at a non-zero relative speed with respect to the second substrate 11b while being subjected to a magnetic force (solid line Fm in the figure) in a direction perpendicular to the surface of the second substrate 11b. As a result, the second particles P2 carried by the support material S2 are transported while being rubbed against the uneven pattern on the surface of the second substrate 11b.

[0115] The mass % of the second particles P2 in the filler 241b (the ratio of the mass of the second particles P2 to the total mass of the filler 241b) is expressed by the following formula (2) using the coverage S2 of the surface area of ​​the magnetic particles (carrier) by the supported second particles P2. The coverage S2 indicates the ratio of the total cross-sectional area of ​​the second particles P2 to the surface area of ​​the magnetic particles (carrier). Mass % of the second particles P2 in the filler 241b = (400 x ρ Ｐ２ ×r Ｐ２ × S2) / (100 × ρ ｃ ×r ｃ +4×ρ Ｐ２ ×r Ｐ２ ×S2) Equation (2) (The symbols in equation (2) represent the following: ρ Ｐ２: true density of the second particle P2, r Ｐ２ : particle size (r50) of the second particle P2, ρ ｃ : true density of magnetic particles, r ｃ : particle size of the magnetic particle (r50), S2: coverage rate of the second particles P2 relative to the surface area of ​​the magnetic particle)

[0116] The mass % of the second particles P2 in the filler 241b is not particularly limited, but is preferably in the range of 5 to 40 mass %, or 10 to 30 mass %. Furthermore, the coverage S2 in the above formula (2) is preferably adjusted to 30 to 200 area %, and more preferably adjusted to 50 to 100 area %. The particle diameters (r50) of the second particles P2 and the magnetic particles (support material) can be determined by laser diffraction / scattering particle size distribution measurement. The true density of the second particles P2 and the magnetic particles (support material) can be determined by pycnometer method.

[0117] At this time, the opening width of the recesses of the uneven pattern is set to a size that allows the second particles P2 to contact the recesses but prevents the support material S2 from contacting them. That is, the opening diameter of the recesses of the uneven pattern on the second substrate 11b is preferably larger than the cumulative 50% particle size (median diameter) of the second particles P2 in the volume-based particle size distribution. Furthermore, the opening diameter of the recesses is preferably smaller than the average size of the support material S2. Here, the opening diameter of the recesses of the uneven pattern is preferably the opening diameter in the short direction of the recesses, and more preferably the maximum opening diameter in the short direction of the recesses. This allows only the second particles P2 in the filler 241b to selectively contact the recesses.

[0118] The second particles P2 that come into contact with the recesses are strongly restrained by the physical restraining force due to the structure of the concave-convex pattern, and by the electrostatic adhesion and adhesive force with the second substrate 11b and the structural material that constitutes the concave-convex pattern (here, the first particles P1), and are detached from the support material S2. Note that, for the sake of explanation, in Figure 8, the second particles P2 are supported on the surface of the support material S2, but it is also acceptable for there to be second particles P2 that are not supported on the support material S2 during the agitation, supply, or transport of the filler 241b.

[0119] 9A is a diagram schematically illustrating the second substrate 11b after the first particles P1 have been transferred by the transfer unit 25a, as viewed from a direction perpendicular to the substrate surface. As shown in FIG. 9A, a honeycomb pattern is formed on the second substrate 11b, in which the first particles P1 are arranged in regular hexagonal arrangement regions.

[0120] The first particles P1 are densely arranged within this regular hexagonal region, and the other areas (white areas in FIG. 9A ) are free of the first particles P1, leaving the adhesive portion of the surface of the second substrate 11b exposed. The regular hexagonal region in which the first particles P1 are held is referred to as the first pattern portion. The honeycomb pattern region in which the second particles P2 are held and which corresponds to the gaps in the first pattern portion is referred to as the second pattern portion.

[0121] 9B is a schematic diagram of the second substrate 11b after the second particles P2 have been filled by the second filling device 24b, viewed from a direction perpendicular to the substrate surface. As shown in FIG. 9B, the second particles P2 are densely arranged in the areas where the first particles P1 were not arranged and the adhesive portion was exposed. Furthermore, the first particles P1 and the second particles P2 are densely arranged at the boundary between the area where the first particles P1 are arranged and the area where the second particles P2 are arranged. Note that particles can also be filled in the small gaps between the first particles P1 using a similar method. In this case, it is possible to fill the gaps between the first particles P1 using a filler containing particles with a particle size corresponding to the gaps between the first particles P1 using the same method as described above, thereby forming an even denser thin film.

[0122] 10 is a diagram schematically illustrating the configuration of the particle arrangement device 2. The particle arrangement device 2 is a device that forms a particle layer 12 on the substrate 11, and includes a storage container 21 that stores and supplies the substrate 11, and a belt device 22 that transports the substrate 11. The particle arrangement device 2 may also include a liquid application device 201 that applies a liquid for providing adhesive portions on the substrate 11. In this case, in order to densely arrange the particles on the substrate 11, it is preferable to apply the liquid in a pattern on the substrate 11.

[0123] The liquid applying device 201 may be a device that ejects liquid by an inkjet method or a device that applies liquid, but a plate-based method such as a flexographic printing method may also be used. Of these, it is preferable to use a device that ejects liquid by an inkjet method as the liquid applying device. Devices that eject liquid by an inkjet method may be devices using various ejection methods, such as a thermal type, a piezo type, an electrostatic type, or a continuous type.

[0124] The liquid applied by the liquid application device 201 may be water-based or oil-based, as long as it contains a material to which the first particles P1 can be attached. A material that does not react with the first particles P1 can be selected as appropriate. The liquid application device 201 may also form the pattern L1 using a plurality of types of liquid. For example, the liquid application device 201 may apply two types of liquid that react with each other on the substrate 11 to increase adhesion. Examples of materials to which the first particles P1 can be attached include resins such as acrylic resins.

[0125] The powder application device 202 applies powder containing the first particles P1 to the substrate 11 on which the liquid has been arranged in a pattern, thereby fixing the first particles P1 by the material on the substrate 11 in a pattern corresponding to the pattern L1.

[0126] The means for applying the powder by the powder applying device 202 may be a means for spraying or sprinkling the powder toward the substrate 11. The powder applying device 202 may further include a means for removing the first particles P1 that have not been fixed to the substrate 11 by means of vibration, centrifugation, air blowing, suction, or the like.

[0127] The particle arrangement device 2 may further include a drying device that evaporates at least a portion of the liquid applied by the liquid application device 201 to control the amount of material on the substrate 11, the thickness of the pattern L1, and the like. This drying device may be provided downstream of the liquid application device 201 and upstream of the powder application device 202. The material on the substrate after drying may be a liquid, a liquid containing solids, or only solids.

[0128] After the first particles P1 are fixedly disposed on the substrate 11, a liquid is applied by a liquid application device 203 to provide adhesive portions at least in areas where the first particles P1 were not disposed. The liquid application device 203 has the same function as the liquid application device 201. The second particles P2 are applied to the substrate 11 to which the liquid has been applied by the liquid application device 203, using a second filling device 24. As a result, a dense particle layer 12 is formed on the substrate 11.

[0129] Furthermore, like the particle arrangement device 1, the particle arrangement device 2 may have a transfer unit. In this case, the transfer unit is provided downstream of the powder application device 202. The first particles P1 are transferred from the substrate 11 to another substrate having an adhesive portion. In the substrate to which the first particles P1 have been transferred, the second particles P2 can be arranged using the second filling device 24 in areas where the first particles P1 are not arranged and the adhesive portion is exposed. This makes it possible to arrange the first particles P1 and the second particles P2 densely on the adhesive portion of the resin substrate.

[0130] Using the above-mentioned particle placement device 1 or particle placement device 2, first particles P1 are placed on the adhesive portion of the resin substrate in the first step (S101 in FIG. 1) of FIG. 1, and second particles P2 are placed on the adhesive portion of the same resin substrate in the second step (S102 in FIG. 1) of FIG.

[0131] (Steps 3 and 4) Step 3 is a particle precipitation step in which the first particles P1 and the second particles P2 arranged on the surface of the adhesive portion on the resin substrate are precipitated into the adhesive portion. The particle precipitation step exposes new adhesive portions between the precipitated first particles P1 and second particles P2. Step 4 is a step in which third particles P3 are arranged in the adhesive portions between the precipitated first particles P1 and second particles P2 to obtain an electrode substrate. The steps will be described below in order.

[0132] The third particles P3 are solid electrolyte particles that can correspond to the second solid electrolyte particles in the electrode substrate. The above-described materials can be used as the solid electrolyte particles. Furthermore, the cumulative 50% particle size (r50) of the primary particles of the third particles P3 in the volume-based particle size distribution is smaller than the r50 of the second particles P2.

[0133] The particle size of the third particles P3 is not particularly limited as long as it is smaller than that of the second particles P2. For example, the third particles P3 preferably have a cumulative 10% particle size (r10) in the volume-based particle size distribution of primary particles of 0.10 to 1.5 μm, more preferably 0.20 to 1.0 μm. Furthermore, the cumulative 50% particle size (r50) in the volume-based particle size distribution is preferably 0.30 to 3.0 μm, more preferably 0.50 to 1.5 μm. Furthermore, the cumulative 90% particle size (r90) in the volume-based particle size distribution is preferably 0.5 to 20.0 μm, more preferably 1.0 to 15.0 μm.

[0134] For example, the ratio {(r50(P3)) / (r50(P2))} of the cumulative 50% particle size (r50(P3)) in the volume-based particle size distribution of the primary particles of the third particles P3 to the cumulative 50% particle size (r50(P2)) in the volume-based particle size distribution of the primary particles of the second particles P2 is preferably 0.01 to 1.0, and more preferably 0.01 to 0.5.

[0135] The ratio of the particle size of the primary particles of the first particles P1 to the particle size of the primary particles of the third particles P3 is not particularly limited. For example, the ratio of the cumulative 50% particle size (r50(P3)) in the volume-based particle size distribution of the primary particles of the third particles P3 to the cumulative 50% particle size (r50(P1)) in the volume-based particle size distribution of the primary particles of the first particles P1, {(r50(P3)) / (r50(P1))}, is preferably 0.01 to 1.0, and more preferably 0.01 to 0.5.

[0136] As described above, the first particles P1 are active material particles. The second particles P2 are particles that may correspond to the first solid electrolyte particles in the electrode substrate after manufacture. The third particles P3 are particles that may correspond to the second solid electrolyte particles in the electrode substrate after manufacture. That is, in the method for manufacturing an electrode substrate, the third step can be described as a particle settling step of settling the first solid electrolyte particles and active material particles arranged on the surface of the adhesive portion into the adhesive portion. Furthermore, the fourth step can be described as a step of arranging the second solid electrolyte particles in the adhesive portion between the settled first electrolyte particles and active material particles.

[0137] FIG. 11 is a schematic diagram showing the devices for the third and fourth steps. The substrate 11 on which the particle layer 12 has been formed by the particle placement device 1 or particle placement device 2 is transferred to the belt device shown in FIG. 11. The belt device is provided with a particle settling device 25 on the upstream side and a third filling device 24 downstream thereof for placing the third particles P3. The particle settling device 25 has pressure rollers 223c and 223d, and the pressure roller 223d rotates drivenly. At least one of the pressure rollers 223c and 223d is preferably a soft roller having an elastic layer on its surface. For example, a soft roller having an elastic layer of silicone rubber or fluororubber on the surface of a stainless steel core can be used. A heater (not shown) may also be built into at least one of the pressure rollers 223c and 223d.

[0138] The substrate 11 is transported by a belt device to a pressure section between the pressure rollers 223c and 223d. When the substrate 11 is pressed by the pressure rollers 223c and 223d, the first particles P1 and the second particles P2 arranged on the surface of the adhesive portion on the substrate settle into the adhesive portion on the substrate. At this time, the above-mentioned heater may be used to facilitate settling of the particles into the adhesive portion on the substrate. Furthermore, a heat source may be provided upstream of the particle settling device 25 to heat the adhesive portion on the substrate.

[0139] Since the pressure roller 223c comes into contact with the particle layer 12 on the substrate, it is preferable to coat the surface with a material with good releasability, such as fluorine, to prevent particles from adhering to the pressure roller 223c. A cleaning mechanism for removing particles adhering to the pressure roller 223c may also be provided. It is even more preferable to apply pressure to the particle layer 12 while it is covered with a protective material (not shown). In this case, the protective material used is preferably a material with good releasability, such as a fluorine sheet if it is resin, or nichrome foil if it is metal. When a protective material is used, a removal mechanism (not shown) for removing the protective material is provided downstream of the particle settling device 25 and upstream of the third filling device 24.

[0140] The particle settling device 25 may be any other known pressurizing device. For example, an isostatic pressure pressurizing device (CIP / HIP), a uniaxial pressure pressurizing device, or even a weight or magnet may be used for pressurization. Furthermore, if the particles have a high specific gravity, the particles may be allowed to settle by their own weight. In this case, it is preferable to promote the settling of the particles by storing the substrate on which the particles are placed under heating, such as in an oven.

[0141] When storing a substrate on which particles are arranged under heating, the temperature and storage time are appropriately adjusted according to the physical properties (shape, particle size, specific gravity, adhesiveness, and viscoelasticity) of the particles and adhesive material. If the temperature or storage time is insufficient, the particles will not settle sufficiently, and the adhesive portion will not be exposed to the surface through the gaps between the particles. On the other hand, if the temperature or storage time is excessive, the particles will move in the planar direction as they settle, significantly reducing the particle density. The temperature is preferably 10 to 90°C, more preferably 40 to 80°C. The storage time is preferably 1 to 24 hours, more preferably 3 to 15 hours.

[0142] In addition to known pressure devices, pressure may be applied by friction with magnetic particles. That is, the particle settling device 25 is performed by the fourth filling device 24. The fourth filling device contains only magnetic particles instead of a filler. The fourth filling device causes the magnetic particles to rub against the substrate 11, causing the first particles P1 and the second particles P2 on the substrate to settle into the adhesive portion on the substrate.

[0143] This also has the effect of rearranging the first particles P1 and the second particles P2 on the substrate by the magnetic particles. Rearrangement refers to the process of more stably fixing the first particles P1 and the second particles P2 by disposing or removing excess particles not fixed to the adhesive portion on the substrate in the gaps between particles, or by moving or rotating particles that are unstably fixed to the adhesive portion, thereby promoting densification of the particles on the substrate. In other words, rearrangement can make the particle layer on the resin substrate denser.

[0144] 12A and 12B are schematic cross-sectional views of the substrate 11 for explaining the settling of particles on the substrate 11 by the particle settling device 25. Fig. 12A shows the state before the third step in which the first particles P1 and the second particles P2 are settling on the adhesive portion 13 on the substrate 11, and Fig. 12B shows the state after the third step. Note that in Figs. 12A and 12B, for convenience of explanation, the first particles P1 and the second particles P2 are depicted as spherical and having the same particle diameter.

[0145] As shown in FIG. 12A, before the third step, particle settling is limited. On the other hand, after the third step, particle settling progresses significantly, and the adhesive portions 13 pushed out by the settling of the particles are exposed to the surface through the gaps between the particles. For example, the particle settling step exposes the adhesive portions on the surface side. FIG. 13 is a schematic diagram of the substrate 11 after the third step from above (the particle layer side, i.e., the side where the first particles P1 and the second particles P2 are arranged). A cross section of the substrate 11 after the third step is shown in FIG. 12B. As the first particles P1 and the second particles P2 settle into the adhesive portions 13, the adhesive portions 13 are exposed to the upper surface of the particle layer through the gaps between the particles, and tiny recesses (e.g., A in FIG. 13) having adhesive portions on their bottom surfaces are formed between the particles.

[0146] In the fourth step, the substrate 11 after the third step (FIGS. 12B and 13) is transported by a belt device to a filling position of a third filling device 24 for disposing the third particles P3. Similar to the first and second filling devices, the third filling device 24 is a filling device that fills using magnetic particles, brush fibers, or elastic material as a carrier material. The following description will be given of a configuration using magnetic particles as a carrier material.

[0147] The filler 241c contained in the third filling device includes third particles P3 and a support material S3 supporting the third particles P3. Here, the third particles P3 may correspond to second solid electrolyte particles. The third particles P3 (second solid electrolyte particles) have a smaller average circular equivalent diameter of primary particles than the second particles P2 (which may correspond to first solid electrolyte particles). Therefore, the third particles P3 are selectively filled into the minute recesses having the adhesive portions by friction of the filler. At this time, the support material S3 is sufficiently large relative to the opening width of the minute recesses having the adhesive portions, and therefore is not filled. The support material S3 may be the same as or different from the support materials S1 and S2 described above.

[0148] The mass % of the third particles P3 in the filler 241c (the ratio of the mass of the third particles P3 to the total mass of the filler 241c) is expressed by the following formula (3) using the coverage S3 of the supported third particles P3 to the surface area of ​​the magnetic particles (support material). The coverage S3 indicates the ratio of the total cross-sectional area of ​​the third particles P3 to the surface area of ​​the magnetic particles (support material). Mass % of the third particles P3 in the filler 241c = (400 × ρ Ｐ３ ×r Ｐ３ × S3) / (100 × ρ ｃ ×r ｃ +4×ρ Ｐ３ ×r Ｐ３ ×S3) Equation (3) (The symbols in equation (3) respectively indicate the following: ρ Ｐ２ : true density of particle P3, r Ｐ２ : particle diameter (r50) of particle P3, ρ ｃ : true density of magnetic particles, r ｃ : particle size of the magnetic particle (r50), S3: coverage rate of the third particles P3 relative to the surface area of ​​the magnetic particle)

[0149] The mass % of the third particles P3 in the filler 241c is not particularly limited, but is preferably in the range of 0.1 to 20 mass %, or 1 to 10 mass %. Furthermore, the coverage S3 of the above formula (3) is preferably adjusted to 30 to 200 area %, and more preferably adjusted to 50 to 100 area %. The particle diameters (r50) of the third particles P3 and the magnetic particles (support material) can be determined by laser diffraction / scattering particle size distribution measurement. Furthermore, the true density of the third particles P3 and the magnetic particles (support material) can be determined by pycnometer method.

[0150] 14 is a schematic diagram of the upper side of the substrate 11 after the fourth step, i.e., the region where the particle layer is formed, as viewed from the vertical direction of the substrate. The third particles P3 are arranged in the minute recesses described above. For the sake of explanation, the third particles P3 are depicted as spherical and having the same particle size, but multiple amorphous third particles P3 can be arranged to fit the openings of the recesses.

[0151] A simple device that does not use a belt device can also be used as the third filling device 24. Fig. 15 shows an example of the device. The third filling device 24 has a filling container 242, a stirring screw member 243, a magnetic member 247, a magnet 248, and a regulating member 250.

[0152] FIG. 16 is a schematic diagram illustrating the operation of the filling device. The filler 241, thoroughly stirred by the stirring screw member 243, is supplied in an appropriate amount by the magnetic member 247 (arrow a in the figure), which has moved from its home position, and the regulating member 250. The supplied filler 241 is rubbed on the substrate 11 as the magnetic member 247 moves back and forth (arrow b in FIG. 16). After the desired number of rubs, the magnetic member 247 moves to a distant home position where the magnetic force acting on the filler 241 on the substrate is sufficiently weakened (arrow c in FIG. 16). The filler 241 on the substrate falls downward due to gravity and is collected in a collection container (not shown). It is preferable to use air blowing or vibration during this process. Alternatively, instead of rubbing on an inclined surface, the filler 241 may be collected by rubbing on a flat surface, and then the magnetic member 247 may be reciprocated again to collect the remaining filler 241 on the substrate. It is preferable to use air blowing or vibration during each collection process. It should be noted that the first particles P1 and the second particles P2 can also be arranged in the same manner using the same simple device.

[0153] In the electrode substrate, the coverage of the resin substrate surface by the active material particles and solid electrolyte particles is preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more. In the present disclosure, the coverage of the resin substrate surface refers to the ratio (area %) of the area covered by the active material particles and solid electrolyte particles to the total area of ​​the resin substrate surface. The coverage of the substrate surface by the active material particles and solid electrolyte particles can be measured by photographing the area where the particle layer is formed using an optical microscope from the direction perpendicular to the substrate and calculating the area ratio of the area covered by the active material particles and solid electrolyte particles using image processing software. Details of the measurement method will be described later.

[0154] The upper limit of the coverage is not particularly limited, but is preferably 99% or less, and more preferably 98% or less. For example, the coverage of the resin substrate surface by the active material particles and solid electrolyte particles is preferably in the range of 60 to 99%, 70 to 99%, 80 to 99%, 60 to 98%, 70 to 98%, or 80 to 98%. When the coverage is in the above range, a dense particle layer is formed on the substrate, improving the density of the particles in the electrode. As a result, ionic conductivity can be improved.

[0155] <Electrode Manufacturing Method> An example of an electrode manufacturing method will be described in detail below with reference to the drawings. The following description will be given taking a positive electrode using positive electrode active material particles as an example, but the manufacturing method described below can be used to manufacture electrodes regardless of whether they are positive electrodes or negative electrodes.

[0156] The method for manufacturing an electrode includes the following three steps (steps 1, 2, and 3): (1) step 1 of stacking a plurality of electrode base materials to form a laminate (S201 in FIG. 17), (2) step 2 of removing the resin base material from the laminate to obtain a three-dimensional object (S202 in FIG. 17), and (3) step 3 of pressurizing the three-dimensional object to obtain an electrode (S203 in FIG. 17).

[0157] That is, the electrode is manufactured by a manufacturing method including the steps of stacking a plurality of electrode base materials and forming a laminate, removing the resin base material from the laminate to obtain a three-dimensional object, and applying pressure to the three-dimensional object. For example, a sintered body of the above-mentioned electrode base material can be used as the electrode. Each step of the electrode manufacturing method will be described in detail below.

[0158] (First Step) The first step is a step of stacking a plurality of electrode base materials to form a laminate. The number of layers is not particularly limited and is determined according to the desired electrode capacity. For example, it is preferable to stack three or more of the above-mentioned electrode base materials. Furthermore, the electrode base materials to be stacked may be the same, or different electrode base materials may be stacked.

[0159] That is, the electrode substrate can also be used as an electrode substrate laminate in which a plurality of electrode substrates are stacked. As described above, the electrode substrate has a resin substrate and a particle layer formed on the resin substrate. When stacking electrode substrates, it is preferable to stack them so that the electrode substrate laminate has alternating resin substrates and particle layers. That is, it is preferable that the electrode substrate laminate has a configuration in which the resin substrates and particle layers are alternately present in the cross section of the electrode substrate laminate. For example, a sintered body of the electrode substrate laminate can be used as an electrode. Furthermore, it is preferable that the laminate is formed on an electrode current collector as a substrate. That is, it is preferable that the electrode has a substrate. As the electrode current collector, known current collectors such as Al foil, SUS foil, Cu foil, Cu—Ni foil, platinum foil, and gold foil can be used. An electrolyte may also be used as the substrate.

[0160] In this case, the electrolyte may be a separately prepared solid electrolyte sheet or an electrolyte substrate consisting of only solid electrolyte particles on a similar substrate. That is, a solid electrolyte can be used as the electrolyte. Furthermore, the solid electrolyte sheet or electrolyte substrate may have a negative electrode or a negative electrode substrate formed on the opposite side from the stacking surface of the positive electrode substrate.

[0161] 18 is a diagram showing a schematic configuration of a laminate forming apparatus. The laminate forming apparatus includes a conveying device 31 that conveys a substrate 11 on which a particle layer 12 is formed, and a stage 32 that can be moved back and forth in the vertical direction by an actuator (not shown).

[0162] The conveying device 31 receives the substrate 11 having the particle layer 12 formed using the particle placement device, and conveys it to the stage 32. Examples of the conveying device 31 that can convey the substrate 11 include a belt conveyor, a roller, and a robot arm. When the substrate 11 is conveyed to the stage 32 by the conveying device 31, the stage 32 moves in the vertical direction by an amount corresponding to the thickness of the substrate 11 and the particle layer 12. By repeating the conveying by the conveying device 31 and the movement of the stage 32, multiple substrates 11 each having a particle layer 12 formed thereon are stacked, and the laminate 15 is formed.

[0163] In this case, it is preferable that the back surface of the substrate 11 on which the particle layer 12 is formed has an adhesive portion. This adhesive portion allows the substrates to adhere to each other, increasing the strength of the laminate and preventing misalignment between the substrates even after the first step. Furthermore, the particle layer 12 between the substrates is sandwiched between the upper and lower adhesive portions, preventing misalignment during processing or storage of the laminate. The adhesive portion may be applied by a coating device (not shown) before lamination, or a pre-coated substrate may be used and the protective film coated on the coated surface may be peeled off before lamination.

[0164] It is preferable to have a de-electrification step of de-electrifying the substrate immediately before the laminate 15 is formed. The particle layer 12 and the substrate 11 formed using the particle placement device are easily charged, and electrostatic repulsion occurs between the substrates during lamination. Therefore, when laminating in the first step, the substrates tend to peel off or gaps tend to form between the substrates. In the de-electrification step, it is preferable to perform non-contact de-electrification using an electrostatic de-electrification blower or the like. Furthermore, it is preferable to have a de-aeration step of de-aerating the laminate after the laminate 15 is formed in order to reduce gaps between the substrates. In the de-aeration step, it is preferable to perform de-aeration using a vacuum packaging machine or the like.

[0165] (Second Step) The second step is a step of sintering the laminate to remove the resin substrate from the laminate. Fig. 19 is a diagram showing a schematic configuration of a sintering treatment apparatus. The sintering treatment apparatus has a conveying device 41 that conveys the laminate 15 and a heating furnace 42 that heats the laminate 15.

[0166] The conveying device 41 receives the laminate 15 from the laminate forming device and conveys it to the heating furnace 42. Similar to the conveying device 31, the conveying device 41 is preferably a device capable of conveying the laminate 15. Examples of devices capable of conveying the laminate 15 include a belt conveyor, a roller, and a robot arm.

[0167] The heating furnace 42 is a furnace that heats the laminate 15. The heating furnace 42 has a heating means 421, a pressurizing means 422, and an atmosphere adjusting means 423. A firing furnace used for firing ceramics or the like can be used as the heating furnace 42. The pressurizing means 422 pressurizes the laminate 15 being heated in the heating furnace 42, and pressurizes the laminate 15 before and after heating.

[0168] It is preferable that the pressurizing means 422 has a pressurizing portion that pressurizes the laminate 15 and is made of a porous material that allows gas to easily pass through. The atmosphere adjusting means 423 has an atmosphere gas supplying means 423a and a pressure reducing means 423b, and adjusts the atmosphere gas in the processing space of the heating furnace 42. The atmosphere gas may be an oxidizing atmosphere (O ２ ), inert atmosphere (Ar, N ２ etc.) or reducing atmosphere (Ar-H ２ ) can be used, but sintering may also be carried out in air.

[0169] When sintering the laminate, it is preferable to heat the laminate at a temperature equal to or higher than the thermal decomposition temperature of the substrate 11 in the laminate 15, and preferably at a temperature lower than the thermal decomposition temperature of each particle layer in the laminate 15. The temperature to which the laminate is heated is preferably 200°C or higher and 1000°C or lower, more preferably 400°C or higher and 800°C or lower. It is preferable to maintain the sintering temperature for 30 minutes or longer, and more preferably for 1 hour or longer. The thermal decomposition temperature is the temperature at which the weight of the material begins to decrease when the temperature is gradually increased in the heating atmosphere in the sintering treatment device. Therefore, by heating the laminate at a temperature equal to or higher than the thermal decomposition temperature of the substrate 11, the substrate 11 in the laminate can be decomposed to reduce its weight, and the resin substrate can be removed from the laminate.

[0170] The heating temperature is preferably equal to or higher than the thermal decomposition temperature of the base material 11, but is preferably even higher than the thermal decomposition temperature. Specifically, when the temperature is increased from room temperature (25°C) at a rate of 5°C / min in an atmosphere (typically air) during heating in a sintering treatment device and thermogravimetric analysis is performed, the heating temperature is preferably equal to or higher than the temperature at which the mass is reduced to 70% by mass of the initial mass. Specifically, for example, 385°C or higher is preferable.

[0171] Similarly, when thermogravimetric analysis is performed, it is more preferable to heat at a temperature equal to or higher than the temperature at which the mass is reduced to 50% by mass of the initial mass, and even more preferable to heat at a temperature equal to or higher than the temperature at which the mass is reduced to 20% by mass of the initial mass. Specifically, for example, 400°C or higher is preferable, and 450°C or higher is more preferable. This can shorten the time required to remove the resin substrate and increase the removal rate of the resin substrate.

[0172] In this way, when the sintering treatment apparatus removes the substrate 11 by heating, it is preferable that the active material particles and the solid electrolyte particles have a higher thermal decomposition temperature than the substrate 11. In general, inorganic materials tend to have higher thermal decomposition temperatures than organic materials, so it is preferable that the active material particles and the solid electrolyte particles are inorganic materials and the substrate 11 is made of an organic material such as a resin. Furthermore, when the sintering treatment apparatus removes the substrate 11 by heating, it is preferable that the active material particles have a softening point temperature higher than the thermal decomposition temperature of the substrate 11.

[0173] The sintering treatment device preferably removes 90% by mass or more of the resin substrate in the laminate 15 by heating, more preferably removes 95% by mass or more, and even more preferably removes 97% by mass or more. In this process, the resin substrate is preferably burned or gasified and released to the outside as a gas. When the resin substrate gasified by pyrolysis is released to the outside of the laminate as a gas, it may push up the particle layer formed on the resin substrate, disrupting its shape. Therefore, it is preferable to reduce the thickness of the resin substrate to reduce the impact on the particle layer.

[0174] Specifically, the thickness (μm) of the resin substrate is preferably 10 times or less, more preferably 5 times or less, and even more preferably 2 times or less, the thickness of the particle layer on the resin substrate. Here, the thickness of the particle layer refers to the difference between the maximum and minimum values ​​of z in the region (x, y, z) where each particle arranged on the resin substrate is present, when the resin substrate surface is (x, y) and the lamination direction of the resin substrate is (z) in the electrode substrate. The thickness of the resin substrate is preferably 1 μm or more and 1 mm or less. The thickness of the particle layer is preferably 0.1 μm or more and 100 μm or less.

[0175] The thickness of the particle layer on the resin substrate is calculated by observing the cross section of the laminate 15 with a BIB-SEM, determining the particle presence area (x, z) using image processing software, where x is the resin substrate surface and z is the lamination direction of the resin substrate, and then calculating the difference between the maximum and minimum values ​​of z. Here, the BIB-SEM imaging conditions, the required image area, and the image processing method are the same as those described above.

[0176] The thickness of the resin substrate may be determined by BIB-SEM, as with the particle diameter of the active material particles, or may be measured using a digital thickness gauge, etc. In addition, in SEM observation using BIB-SEM, methods for identifying the active material particles, solid electrolyte particles, substrate, and adhesive portion, include a method of elemental composition analysis by EDS.

[0177] The sintering treatment device preferably exhausts the released gas to the outside of the heating furnace 42 using the pressure reducing means 423b. By creating an oxidizing atmosphere, i.e., an atmosphere containing oxygen gas such as air, inside the heating furnace 42 using the atmospheric gas supplying means 423a or the like, the resin base material can be burned and removed. However, depending on the active material particles and solid electrolyte particles used, sintering in an oxidizing atmosphere may cause decomposition or composition changes. In such cases, it is recommended to use an inert atmosphere (Ar, N ２ etc.) or reducing atmosphere (Ar-H ２ ) is preferably sintered.

[0178] As described above, when the resin substrate is gasified by pyrolysis from the laminate 15 and released as a gas, the particle layers in the laminate 15 may be pushed up and deformed. Therefore, when heating in the heating furnace 42, the laminate 15 may be pressurized by the pressurizing means 422 before or during heating.

[0179] FIG. 20A is a BIB-SEM image of the cross section of the laminate after the first step. This is a laminate 15 in which six second substrates 11b, each having a particle layer 12 formed thereon, are stacked on a base 14. FIG. 20B is a BIB-SEM image of the cross section of a three-dimensional object 16 (positive electrode) after the second step. The resin substrate has been removed from the laminate 15, resulting in a three-dimensional object 16 consisting of six particle layers. FIG. 20C is an SEM image of the top of the three-dimensional object 16. The first particles P1 and second particles P2 periodically arranged on the second substrate 11b in the first step are maintained even after the second step.

[0180] (Third Step) The third step is a step of pressurizing the three-dimensional object 16 from which the resin base material has been removed. As a method of pressurizing, the three-dimensional object 16 can be pressurized by a pressurizing means 422 during cooling or heat dissipation after heating. Alternatively, after the resin base material is removed by a sintering treatment device, pressure can be applied by a separate pressurizing device. Specific pressing methods are preferably vacuum degassing, isostatic pressing, or a general hydraulic press or roller press. Among these, pressing by a combination of vacuum degassing and isostatic pressing is preferred.

[0181] The pressure is preferably 5 MPa to 500 MPa. This fills the voids in the three-dimensional object from which the resin substrate has been removed, improving the density and strength of the three-dimensional object. After the third step, the three-dimensional object may be heated again in a sintering treatment device for sintering. Alternatively, the laminate may be impregnated with a solution in which a conductive additive, a binder resin, etc. are dispersed in a solvent, thereby dispersing each material within the laminate.

[0182] An electrode can be manufactured by a manufacturing method including the above-described steps. The electrode preferably has a substrate and a particle layer containing active material particles and solid electrolyte particles. It is also preferable that voids exist in the particle layer. This configuration can improve ionic conductivity within the electrode and mitigate volume fluctuations of the active material particles.

[0183] 21 is a diagram schematically illustrating the overall configuration of an additive manufacturing system 100. The additive manufacturing system 100 includes a control unit U1, a particle layer forming unit U2, a stacking unit U3, a removal unit U4, and a post-processing unit U5.

[0184] The control unit U1 is responsible for controlling each component of the additive manufacturing system 100. The particle layer formation unit U2 forms a particle layer 12 on a substrate 11 using the particle placement device (FIG. 2) described above. The lamination unit U3 uses the laminate molding device (FIG. 18) described above to stack multiple substrates 11, each with a particle layer 12 formed thereon, to form a laminate 15 including multiple particle layers 12 and multiple substrates 11. The removal unit U4 uses the sintering treatment device (FIG. 19) described above to remove the substrate 11 from the laminate 15 formed in the lamination unit U3 to form a three-dimensional object 16 (electrode). The post-processing unit U5 performs post-processing of the three-dimensional object 16 formed in the removal unit U4. Note that the unit configuration shown in FIG. 21 is merely an example, and other configurations may also be used. The configuration and operation of each unit are described below.

[0185] [Control Unit] The control unit U1 controls each part of the additive manufacturing system 100, specifically the particle layer formation unit U2, the stacking unit U3, the removal unit U4, and the post-processing unit U5. The control unit U1 may include a three-dimensional shape data input unit that accepts input of three-dimensional shape data of a three-dimensional object to be formed by the additive manufacturing system 100 from an external device (e.g., a personal computer). The three-dimensional shape data can be data created and output by a three-dimensional CAD system, a three-dimensional modeler, a three-dimensional scanner, or the like. While any file format is acceptable, the STL (StereoLithography) file format is preferred.

[0186] The control unit U1 may be equipped with a slice data calculation section that slices the three-dimensional shape data at a predetermined pitch to calculate the cross-sectional shape of each layer, and generates image data (referred to as "slice data") to be used for image formation in the particle layer forming unit U2 based on the cross-sectional shape.

[0187] As will be described in more detail below, the particle layer forming unit U2 of this embodiment can use multiple types of materials to form material layers in which each material is patterned. Therefore, slice data corresponding to images of each material may be generated. The slice data file format can be, for example, multi-value image data (each value representing a type of material) or multi-plane image data (each plane corresponding to a type of material).

[0188] Although not shown, the control unit U1 also includes an operation unit, a display unit, and a memory unit. The operation unit has a function to accept instructions from the user. For example, it is possible to input instructions such as turning the power on / off, various settings of the device, and operation instructions. The display unit has a function to present information to the user. For example, it is possible to present various setting screens, error messages, operation status, etc. The memory unit has a function to store three-dimensional shape data, slice data, various setting values, etc.

[0189] In terms of hardware, the control unit U1 can be configured as a computer equipped with a CPU (Central Processing Unit), memory, auxiliary storage device (hard disk, flash memory, etc.), input device, display device, and various I / Fs. Each of the above-mentioned functions is realized by the CPU reading and executing a program stored in the auxiliary storage device or the like and controlling the necessary devices. However, some or all of the above-mentioned functions may be configured with circuits such as ASIC or FPGA, or may be executed by another computer using technologies such as cloud computing or grid computing.

[0190] [Particle Layer Formation Unit] The particle layer formation unit U2 is a unit that forms a particle layer 12 on the substrate 11. The particle placement device (FIG. 2) described above can be used as the particle layer formation unit U2. The additive manufacturing system 100 may have multiple particle layer formation units U2. This allows the particle layers 12 to be formed on the substrate 11 simultaneously and in parallel, further improving the throughput of the formation of laminates and three-dimensional objects. Furthermore, when there are many types of materials that make up the three-dimensional object, providing a particle layer formation unit U2 for each material type or group of material types can eliminate the need to switch material types or processes within the particle layer formation unit U2. This allows the three-dimensional object to be manufactured continuously.

[0191] [Lamination Unit] The lamination unit U3 is a unit that laminates multiple substrates 11, each having a particle layer 12 formed thereon in the particle layer forming unit U2, to form a laminate 15 including multiple particle layers 12 and multiple substrates 11. The laminate molding apparatus described above ( FIG. 18 ) can be used. The lamination unit U3 may further include a conveying device 33 that conveys the formed laminate 15 to the removal unit U4 or the like, and a pressure device (not shown) that pressurizes the laminate 15 in the stacking direction. The conveying device 33 may have a configuration similar to that of the conveying device 31.

[0192] [Removing Unit] The removing unit U4 is a unit that removes the base material 11 from the laminate 15 formed in the laminating unit U3 to form a three-dimensional object 16. The above-described sintering treatment device (FIG. 19) can be used.

[0193] [Post-processing unit] The post-processing unit U5 is a unit that performs post-processing of the three-dimensional object 16 formed by the removal unit U4. The type of post-processing performed by the post-processing unit U5 is not particularly limited, but examples include a process of further heating and sintering the three-dimensional object 16. Note that when the post-processing unit U5 performs a heat treatment as a post-processing, the removal unit U4 may also perform that function. By sintering the three-dimensional object 16, particles within and between particle layers can be sintered.

[0194] Furthermore, reducing gases such as carbon monoxide generated when the resin substrate is removed may change the composition and reduce ionic conductivity depending on the active material particles and solid electrolyte particles used. In this case, the composition can be changed again by sintering (oxidation) in the post-treatment unit U5, thereby improving ionic conductivity. Of course, in sintering in the post-treatment unit U5, in addition to an oxidizing atmosphere with a controlled oxygen concentration, Ar or N ２ or ArH ２ It is also possible to sinter in a reducing atmosphere such as

[0195] An example of post-treatment other than sintering is a process in which the laminate is impregnated with a solution in which a conductive additive, a binder resin, etc. are dispersed in a solvent, thereby dispersing each material within the laminate. After dispersion, a drying process or a pressurizing process may be included to volatilize the solvent and fix the binder.

[0196] A secondary battery has electrodes (positive and negative electrodes), an electrolyte layer adjacent to the electrodes, and, if necessary, a current collector. For example, an electrode manufactured using the above-mentioned electrode substrate can be used as the positive electrode. The electrode can be manufactured, for example, by the above-mentioned method. Furthermore, known materials can be used as the negative electrode without any particular limitation. Examples of such materials include negative electrodes containing metal foils that form a lithium alloy layer, such as lithium metal, indium, tin, aluminum, zinc, and magnesium, graphite particles (graphite, hard carbon, soft carbon, etc.), silicone particles, and lithium titanate particles.

[0197] The electrolyte layer is not particularly limited and any known material can be used. For example, Li １．５ Al ０．５ Ge １．５ P ３ O １２ (hereinafter also referred to as LAGP), Li １．３ Al ０．３ Ti １．７ P ３ O １２ (hereinafter also referred to as LATP), Li ５．９ Yb ０．８１ La ０．０９ Zr ０．１ (BO ３ ) ３ (hereinafter also referred to as LYbBO), Li ３ BO ３ (hereinafter also referred to as LBO), Li ６．２５ La ３ Zr ２ Al ０．２５ O １２ (hereinafter also referred to as LLZ), Li ０．３３ La ０．５５ TiO ３(hereinafter also referred to as LLT), etc. can be used. Furthermore, the electrolyte may be an electrolyte sheet obtained by pelletizing a material using a pressure device or the like and sintering it. The current collector is not particularly limited, and known materials can be used. For example, aluminum, stainless steel, platinum, gold, etc. can be used as a positive electrode current collector. Furthermore, copper, copper-nickel, platinum, gold, etc. can be used as a negative electrode current collector. The above metals that can be used as current collectors may also be used as metal foils.

[0198] <Method for manufacturing secondary batteries> There are multiple possible methods for manufacturing secondary batteries using the above-described additive manufacturing system 100, but several examples will be given below. A case where the system is used to manufacture a positive electrode or a negative electrode will be described. Using a current collector or an electrolyte formed by a separate means as a base, the system can manufacture a positive electrode, a negative electrode, or both electrodes.

[0199] A secondary battery can be manufactured by laminating an electrode, a current collector, and an electrolyte, optionally packaging the laminate with an aluminum laminate film or the like, and then molding and pressurizing the laminate. That is, a method for manufacturing a secondary battery may include a step of laminating an electrode, a current collector, and an electrolyte. The electrode may be the electrode described above. Also, a method for manufacturing a secondary battery may include a step of preparing an electrode by the electrode manufacturing method described above and a step of providing a solid electrolyte adjacent to the electrode. Also, a method for manufacturing a secondary battery may include a step of simultaneously providing the electrode and the solid electrolyte adjacent to the electrode. That is, the electrode and the solid electrolyte may be prepared separately in separate steps, or may be prepared simultaneously in the same step.

[0200] Here, the alternative means for forming the electrolyte is a known means, such as pelletizing solid electrolyte particles using a uniaxial press or the like and sintering them in an electric furnace or the like. The electrolyte may be an electrolyte sheet or the like. By stacking the produced components in the order of positive electrode current collector, positive electrode, electrolyte, negative electrode, and negative electrode current collector, a laminated secondary battery packed in a laminate film or a coin-type secondary battery packed in a coin case can be produced.

[0201] The particles constituting the positive electrode, electrolyte, and negative electrode may differ in the appropriate temperature and atmosphere during sintering. When handling such materials, it is preferable to separately manufacture the positive electrode, electrolyte, and negative electrode components and assemble them into a battery. Furthermore, when lithium metal or indium is used as the negative electrode, it is preferable to use the negative electrode as a metal foil or to form it into a current collector or electrolyte by a vacuum process such as sputtering. Because lithium metal has a strong reducing power, it is easily decomposed depending on the type of solid electrolyte. In this case, a buffer layer may be provided between the electrode and the electrolyte. It is preferable to use a polymer electrolyte or the like as the buffer layer.

[0202] The above example is an example in which a positive electrode or negative electrode laminate is formed using the additive manufacturing system 100 to manufacture an electrode, but it is also possible to form a laminate containing two or more of the main components of a secondary battery, namely a positive electrode current collector, a positive electrode, an electrolyte, a negative electrode, and a negative electrode current collector, and manufacture it as a three-dimensional object.

[0203] For example, each substrate is produced by the particle layer forming unit U2. That is, a positive electrode current collector substrate, a positive electrode substrate, an electrolyte substrate, a negative electrode substrate, and a negative electrode current collector substrate. Each substrate may contain multiple types of particles (positive electrode active material particles and solid electrolyte particles) like the positive electrode substrate, or may contain only a single type of particle. When only a single type of particle is contained, a dense particle layer containing only a single type of particle can be formed on the substrate by filling the filling devices 24a and 24b with the same type of filler.

[0204] The electrolyte base material is formed of a particle layer containing at least solid electrolyte particles. The negative electrode base material is formed of a particle layer containing at least negative electrode active material particles. The current collector base material is formed of a particle layer containing at least conductive particles. These base materials are stacked in the following order: positive electrode current collector base material, positive electrode base material, electrolyte base material, negative electrode base material, and negative electrode current collector base material using the stacking unit U3 to produce a laminate, and a secondary battery can be manufactured using the removal unit U4 and post-processing unit U5. Furthermore, a bipolar secondary battery can also be manufactured by stacking electrode base materials on both sides of the current collector base material.

[0205] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. In the following examples, unless otherwise specified, the number of parts is based on parts by mass.

[0206] The positive electrode of a secondary battery was formed using the above-described additive manufacturing system 100. Specifically, a particle layer was formed on a resin substrate using the particle layer formation unit U2 shown in FIG. 21, and the substrate on which the particle layer was formed was laminated (three layers) on a current collector (Al foil) using the lamination unit U3 to form a laminate. Then, using the removal unit U4, the resin substrate was removed from the laminate by heating, and a three-dimensional positive electrode was formed by applying pressure. The sintering atmosphere and sintering temperature (maintained for 1 hour) are as shown in Table 4 below.

[0207] The electrolyte is Li １．５ Al ０．５ Ge １．５ P ３ O １２ The electrolyte sheet (260 μm thick) was formed by pelletizing the LAGP (hereinafter also referred to as LAGP) powder using a uniaxial press and sintering it in an electric furnace (850°C / 12h). An indium foil (50 μm thick) was used as the negative electrode. Aluminum foil (20 μm thick) was used as the positive electrode current collector. Copper foil (20 μm thick) was used as the negative electrode current collector. The above materials were stacked in the order of positive electrode current collector, positive electrode, electrolyte, negative electrode, and negative electrode current collector. The stack was then packaged in an aluminum laminate film so that the tab lead for the extraction electrode, previously welded to the current collector, was positioned outside the laminate. The stack was then molded into a laminate cell shape using a vacuum packaging machine and pressurized (196 MPa) using an isostatic press to produce an all-solid-state secondary battery.

[0208] A polyester (PET) sheet was used as the first substrate 11a. A honeycomb-shaped concave-convex pattern was formed on the first substrate 11a using a pattern forming device 23. First, an ultraviolet-curable resin (ultraviolet-curable liquid silicone rubber, PDMS, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the first substrate 11a. Then, a film mold (standard mold, manufactured by Soken Chemical & Engineering Co., Ltd.) having a honeycomb-shaped concave-convex pattern on its surface corresponding to the desired concave-convex pattern was pressed against the ultraviolet-curable resin on the first substrate 11a. With the film mold pressed against the first substrate 11a, ultraviolet light was irradiated from a UV lamp to cure the ultraviolet-curable resin, and the film mold was then released.

[0209] The structure of a first substrate 11a having a concave-convex pattern 111a formed on its surface is shown in Figures 22A and 22B. Figure 22A is a top view of the first substrate 11a, and Figure 22B is a cross-sectional view taken along the line A-A in Figure 22A. As shown in Figures 22A and 22B, a honeycomb-shaped concave-convex pattern having hexagonal frame-shaped convex portions is formed on the surface of the first substrate 11a. Here, as shown in Figure 22B, the width of adjacent convex portions is k (μm), the pitch between adjacent convex portions is s (μm), and the height of the convex portions is d (μm). In the following examples, the shape of the concave-convex pattern was measured using a non-contact surface / layer cross-sectional shape measurement system (VertScan 2.0, manufactured by Ryoka Systems Co., Ltd.).

[0210] The second substrate 11b was a polyester (PET) sheet coated with an acrylic adhesive on both sides. The thickness of the second substrate 11b used was 3 μm. The acrylic adhesive was coated on both sides of the second substrate 11b to form an adhesive portion. The thickness of the formed adhesive portion was 1 μm.

[0211] The first particles P1 are active material particles of LiCoO ２ (hereinafter also referred to as LCO), LiMO ２ (M is an element selected from the group consisting of Ni, Mn, and Co. Hereinafter, also referred to as NMC), LiFePO ４ The second particles P2 and the third particles P3 were solid electrolyte particles, Li３ BO ３ (hereinafter also referred to as LBO), Li ５．９ Yb ０．８１ La ０．０９ Zr ０．１ (BO ３ ) ３ (manufactured by the company; hereinafter also referred to as LYbBO). LCO was manufactured by Nippon Chemical Industry Co., Ltd. (Cellseed C-5H), NMC was manufactured by Nippon Chemical Industry Co., Ltd. (Cellseed NMC), LFP was manufactured by Toshima Manufacturing Co., Ltd., and Li ３ BO ３ The product used was manufactured by Toshima Manufacturing Co., Ltd.

[0212] Furthermore, the solid electrolyte particles were crushed and classified (by Nisshin Engineering Inc.) to separate them into seven particle size distribution levels (small particle size side: A1 / A2 / A3 / B1 / B2 / B3: large particle size side). The particle sizes are shown in Table 2. The support material S1 for the first particles P1, the support material S2 for the second particles P2, and the support material S3 for the third particles P3 were all magnetic standard carriers (Standard Carrier P02 manufactured by the Imaging Society of Japan). The cumulative 50% particle size (median diameter) in the volume-based particle size distribution of the standard carrier was 81 μm.

[0213] <Method for manufacturing electrode substrate 1> LCO (first particles P1) and a standard carrier (support material S1) were stirred and mixed to obtain filler 241a. Using a similar method, LBO (product B2) (second particles P2) and a standard carrier (support material S2) were stirred and mixed to obtain filler 241b. Furthermore, LBO (third particles P3) and a standard carrier (support material S3) were stirred and mixed to obtain filler 241c. Using the obtained fillers 241a-c, a particle layer 1 was formed on a resin substrate by the particle layer forming unit U2 to obtain an electrode substrate 1. At this time, the concave-convex pattern 111a on the first substrate 11a was controlled so that the width k of the concaves was 6 μm, the pitch s of the convex portions was 7.5 μm, and the height d of the convex portions was 5.5 μm. The obtained electrode substrate 1 was designated Example 1.

[0214] <Method for manufacturing electrode substrates 2 to 7> Electrode substrates 2 to 7 were obtained by forming particle layers 2 to 7 under the same conditions as for particle layer 1, except that the type of second particles P2, the type of third particles P3, and the pitch s of the convex portions of the concave-convex pattern 111a on the first substrate 11a were changed as shown in Table 1. The obtained electrode substrates 2 to 7 were designated as Comparative Examples 1 to 6.

[0215] In the manufacturing process of electrode substrates 1 to 7, the compositions of fillers 241a, 241b, and 241c used when forming a particle layer on a resin substrate using particle layer forming unit U2, and the shape of the uneven pattern 111a on the first substrate 11a are shown in Table 1. The support material S1 in filler 241a, the support material S2 in filler 241b, and the support material S3 in filler 241c were all the same as the standard carriers described above. In the table, the mass % of particles indicates the mass % of each particle in each filler.

[0216] Table 2 shows the particle size of the primary particles of each particle in fillers 241a-c. The particle sizes shown in Table 2 are the particle sizes of the material contained in the filler before the particle layer is formed. The particle sizes (r10, r50, r90) of each particle are the particle sizes of the cumulative distribution in the volume-based particle size distribution of the primary particles, with r10 being the particle size at 10% cumulative, r50 being the particle size at 50% cumulative, and r90 being the particle size at 90% cumulative. In other words, r50 is the median diameter. The particle sizes were measured using a laser diffraction / scattering particle size distribution measuring device (LA-960, manufactured by Horiba, Ltd.). The standard carriers used as the support materials S1, S2 and S3 had r10 of 60 μm, r50 of 81 μm and r90 of 113 μm.

[0217] Fig. 23A is an SEM image of the upper side (the side on which the particle layer is formed) of the electrode substrate 1 of Example 1. Within the surface of the electrode substrate, LCO particles P1 are periodically dispersed, and LBO particles P2 and P3 are disposed between the particles. That is, in Figs. 23A to 23C, P1 represents the active material particles of the electrode substrate, P2 represents the first solid electrolyte particles of the electrode substrate, and P3 represents the second solid electrolyte particles of the electrode substrate. Fig. 23B is an enlarged image of Fig. 23A. The LBO includes particles P2, which are a group of particles with large particle diameters, and particles P3, which are a group of particles with small particle diameters.

[0218] FIG. 23C is a BIB-SEM image of a cross section of the electrode substrate 1. A particle layer containing particles P1, P2, and P3 was formed on the resin substrate (second substrate 11b) of the electrode substrate 1. Furthermore, in the particle layer, solid electrolyte particles LBO (product B2) as particles P2 were arranged adjacent to LCO as particles P1. Solid electrolyte particles LBO (product A2) as particles P3 were smaller than particles P2 and were unevenly distributed in the upper part of the particle layer (the opposite side of the second substrate 11b). When the uneven distribution was determined using the method described below, 80% or more by number of particles P3 (solid electrolyte particles LBO (product A2)) were unevenly distributed on the side opposite to the side in contact with the resin substrate. As described above, this is achieved by steps 3 and 4 (S103 and S104 in Figure 1) in which particles P1 and P2 are allowed to settle in the adhesive portion on the resin substrate, and particles P3 are placed in the newly exposed adhesive portion on the surface (Figures 12A, 12B, 13, and 14).

[0219] FIG. 24A is an SEM image (enlarged) of the upper side (the side on which the particle layer is formed) of the electrode substrate 2 of Comparative Example 2. LBO (product A2), which is particle P2 and particle P3, is arranged between the LCO particles. FIG. 24B is a BIB-SEM image of a cross section of the electrode substrate 2. LBO (product A2), which is particle P2 and particle P3, is arranged adjacent to the LCO, which is particle P1, but since the particle diameters of particle P2 and particle P3 are the same, it can be seen that they are each arranged in the same manner on the resin substrate. That is, in Comparative Example 2, uneven distribution of particle P3 as in Example 1 was not confirmed.

[0220] FIG. 25A is an SEM image (enlarged) of the upper side (the side on which the particle layer is formed) of the electrode substrate 5 of Comparative Example 5. LBO (B2 product) which is particle P2 and particle P3 is arranged between the LCO particles. FIG. 25B is a BIB-SEM image of the cross section of the electrode substrate 5. LBO (B2 product) which is particle P2 and particle P3 is arranged adjacent to the LCO which is particle P1, but as in Comparative Example 2, since the particle diameters of particles P2 and P3 are the same, it can be seen that each is arranged in the same manner on the resin substrate. That is, in Comparative Example 5, the uneven distribution of particle P3 as in Example 1 was not confirmed. Similarly, in Comparative Examples 1, 3, 4, and 6, since the particle diameters of particles P2 and P3 are the same, the uneven distribution of particle P3 as in Example 1 was not confirmed.

[0221] Table 3 shows the evaluation results for Example 1 and Comparative Examples 1 to 6. The evaluation method will be explained. In the table, "coverage" refers to the coverage of the active material particles and solid electrolyte particles on the surface of the resin substrate. "re" and "ra" refer to the average equivalent circle diameter of the primary particles of the solid electrolyte particles and active material particles on the surface of the resin substrate. "re10" refers to the equivalent circle diameter of the solid electrolyte particles on the surface of the resin substrate, which is 10% of the cumulative number of re (starting from the small particle size side). "re10 ratio" refers to the ratio of particles (second solid electrolyte particles) that are 10% or less of the cumulative number of solid electrolyte particles on the resin substrate and are located farther from the reference line described below. In other words, an re10 ratio of 0.80 or higher indicates that the second solid electrolyte particles are unevenly distributed on the side opposite the resin substrate in the particle layer. "Presence or absence of uneven distribution" refers to the presence or absence of uneven distribution of the second solid electrolyte particles in the particle layer. A specific method for determining uneven distribution will be described later. The average equivalent circle diameter re of the primary particles of the solid electrolyte particles in Example 1 was 1.1 μm, and the equivalent circle diameter that is 10% of the cumulative number of re was 0.48 μm. That is, it was confirmed that the second particles P2 correspond to the first solid electrolyte particles in the electrode substrate, and the third particles P3 correspond to the second solid electrolyte particles in the electrode substrate.

[0222] The methods for evaluating the electrode substrate and calculating the respective indices will be described below.

[0223] <Coverage ratio> Images for calculating the coverage ratio were obtained by SEM observation. For SEM observation, an electron microscope (S-4800: manufactured by Hitachi) was used to photograph the top surface of the electrode substrate (the side on which the particle layer was formed) from the vertical direction. An example of the photographed SEM image is shown in Figure 30. The photograph was taken under the following conditions: Detector: ESB (backscattered electron image) Observation conditions: Acceleration voltage 2 kV Magnification: 1000x Filter: A bias of 1500 V was applied to the ESB filter

[0224] Next, elemental and compositional analysis of each particle on the resin substrate was performed using SEM-EDX (PV77-47190ME, manufactured by AMETEK Corporation), and active material particles 17 and solid electrolyte particles 18 were identified. In FIG. 30 , the active material particles are shown as white particles, and the solid electrolyte particles are shown as gray particles. The active material particles and solid electrolyte particles are specifically identified by the following method. The resin substrate is analyzed using X-ray diffraction (XRD) or the like to identify the materials that make up the resin substrate. Then, the specific elements contained in the active material particles and solid electrolyte particles can be detected and identified using SEM-EDX. When LCO is used as the first particles P1, which are active material particles, and LBO is used as the second particles P2 and third particles P3, which are solid electrolyte particles, the active material particles are identified by detecting Co using SEM-EDX, and the solid electrolyte particles are identified by detecting B using SEM-EDX.

[0225] The coverage ratio was calculated by determining the proportion of the area where particles existed in the entire screen of the SEM image obtained by the above-mentioned method. Specifically, it was calculated by the following image processing. OpenCV was used for image processing, and analysis was performed using Python. The obtained SEM image was normalized to an average brightness of 100 and a standard deviation of ±30. The normalized image was binarized using a brightness of 60 as a threshold, and an image in which all particles were represented by white pixels was prepared. An example of the prepared image is shown in Figure 31. The proportion of white pixels among all pixels making up the image was analyzed and calculated as the particle coverage ratio. For example, the coverage ratio in Figure 31 is 96.3%.

[0226] <BIB-SEM Imaging Method> BIB-SEM images were used to calculate re and ra, and to determine uneven particle distribution. The BIB-SEM imaging conditions are explained below. Three resin substrates were stacked on a substrate (Al foil), vacuum-packed, and isostatically pressed to prepare a sample. The sample was cut with a wire saw (DWS3400 / wire diameter 170 μm, diamond diameter 30 μm), and the cut surface was cross-sectionally processed with a broad ion beam of Ar (JEOL SM-09010 Cross Section Polisher). The cross-sectional processing conditions were a voltage of 6 kV and a current of 150 to 200 mA. A cross section of the resin substrate and the particle layer in the stacking direction was obtained as a BIB-SEM image, and the cross section was observed.

[0227] The cross section was photographed using an electron microscope (ULTRA55) under the following conditions. Five images were taken from the center of the cross section, with 100 solid electrolyte particles counted per image, using the method described below, so that a total of 500 solid electrolyte particles were counted. An example of the photographed image is shown in Figure 32. Detector: ESB (backscattered electron image) Observation conditions: accelerating voltage 3 kV Magnification: 1000x Filter: bias of 1500 V applied to ESB filter

[0228] Next, elemental and compositional analysis of each particle on the resin substrate was performed using SEM-EDX (XFlash Detector 630M manufactured by Bruker Corporation), and active material particles 17 and solid electrolyte particles 18 were identified. The active material particles and solid electrolyte particles were identified using the method described above. The resin substrate was analyzed using X-ray diffraction (XRD) or the like, and the materials that make up the resin substrate were identified. Thereafter, the specific elements contained in the active material particles and solid electrolyte particles were detected and identified using SEM-EDX using the method described above.

[0229] <re / ra> A method for calculating re / ra using a BIB-SEM image will be described. <Method for calculating ra> Active material particles were detected from BIB-SEM images taken under the above conditions. For detection, the Watershed method, an image boundary detection method, was used. First, the BIB-SEM image was normalized to an average brightness of 100 and a standard deviation of ±30. To count the active material particles on the resin substrate, an image representing only the particle layer on the resin substrate was cut out from the normalized image so as to include all particles in the image. An example of the cut-out image is shown in Figure 33A. The cut-out image was binarized using a brightness threshold of 120, resulting in an image in which only the active material particles are represented by white pixels. An example of the resulting image is shown in Figure 33B. Next, for the purpose of noise removal, the area surrounded by white pixels was filled in white, and then a morphological transformation opening process was performed with a kernel size of 3 x 3 pixels to obtain a noise-removed image. An example of the noise-removed image is shown in Figure 33C. To perform the Watershed method, parts of the image that are definitely background, parts that are definitely foreground (here, active material particles), and parts that cannot be determined are determined. The resulting image is subjected to an expansion process for the white parts, and the black parts are determined to be background. Next, the distance between the foreground and background is calculated, and parts that are 20% or more away from the background are determined to be definitely foreground (active material particles). The area between the foreground and background is defined as a boundary region, and each particle is detected by applying the Watershed method. An example of an image after particle detection is shown in Figure 33D. For example, 21 particles are detected from Figure 33D.

[0230] The number of pixels of each detected particle was counted as the area, and the diameter of a circle equivalent to that area was calculated. By calculating the size of one pixel from the scale of the original image, the diameter of the circle calculated from the number of pixels was converted to an actual diameter, and the equivalent circle diameter of the primary particles was calculated. Specifically, ra can be calculated as follows: ra = (number of pixels of detected particles) x (length per pixel of SEM image (μm)) The particle size of the cumulative 50% particles, counting from the smallest particle size, of the calculated equivalent circle diameters of the primary particles of each active material particle was taken as the average equivalent circle diameter ra of the active material particles. For example, in FIG. 33D, ra = 64.7 (pixels) x 0.04 (μm) = 2.6 (μm).

[0231] <Method for Calculating re> The BIB-SEM image was normalized using the method described above, and an image of the particle layer on the resin substrate was cut out from the normalized image. The cut-out image was binarized using a brightness threshold of 120 to obtain an image in which only the active material particles are represented by white pixels. An example of the resulting image is shown in Figure 33B. The cut-out image was also binarized using a brightness threshold of 90 to obtain an image in which both the solid electrolyte particles and the active material particles are represented by white pixels. An example of the resulting image is shown in Figure 34A. By subtracting the white pixel area of ​​the image in which only the active material particles are represented by white pixels from the image in which both the solid electrolyte particles and the active material particles are represented by white pixels, an image in which only the solid electrolyte particles are represented by white pixels is obtained. An example of the resulting image is shown in Figure 34B. Next, for the purpose of noise removal, the area surrounded by white pixels was filled in white, and then a morphological transformation opening process was performed with a kernel size of 3 x 3 pixels to obtain a noise-removed image. An example of the resulting image is shown in Figure 34C.

[0232] Next, to perform the Watershed method, the image is determined to contain areas that are definitely background, areas that are definitely foreground (here, solid electrolyte particles), and areas where it is unclear which is which. The resulting image is subjected to a dilation process to determine the white areas as background, and the black areas are determined as background. An example of the resulting image is shown in Figure 34D. Next, the distance between the foreground and background is calculated, and areas that are 10% or more away from the background are determined to be definitely foreground (solid electrolyte particles). The area between the foreground and background is also defined as a boundary region. An example of an image showing the boundary region is shown in Figure 34E. The Watershed method was applied to this image to detect each particle. An example of an image after particle detection is shown in Figure 34F. For example, 28 particles are detected from Figure 34F.

[0233] The number of pixels of each detected particle was counted as the area, and the diameter of a circle equivalent to that area was calculated. The size of one pixel was calculated from the scale of the original image, and the diameter of the circle calculated from the number of pixels was converted to an actual diameter, thereby calculating the equivalent circle diameter of the primary particle. Specifically, r e can be calculated as follows: r e = (number of pixels of detected particles) × (length per pixel of SEM image (μm)). The particle size of the calculated equivalent circle diameter of the primary particle of each solid electrolyte particle, which is 50% of the particles in terms of number, starting from the smallest particle size, was defined as the average equivalent circle diameter r e of the solid electrolyte particles. For example, in FIG. 34F , r e = 16.9 (pixels) × 0.04 (μm) = 0.68 μm. Therefore, in the example shown in FIGS. 33D and 34F , r e / r e = 0.68 / 2.6 = 0.26, which confirms that the ratio is 0.01 or more and 2.0 or less.

[0234] <Assessment of Maldistribution> Maldistribution of solid electrolyte particles was assessed by the following method. Below is described a method for determining a reference line for maldistribution, and a method for assessing maldistribution by checking the relationship between the reference line and the position of solid electrolyte particles corresponding to the cumulative 10% particle size. Maldistribution was assessed by observing the cross section of the particle layer using a BIB-SEM. The means for obtaining BIB-SEM images was as described above.

[0235] <Determining the Reference Line of Maldistribution> First, the reference line of maldistribution is determined. As an example, a method for determining the reference line of maldistribution in the BIB-SEM image shown in FIG. 35 is described below. The distribution of active material particles on the resin substrate in the z-axis direction (the lamination direction of the resin substrate and particle layer) was taken as the reference line, and the peak position was used as the reference line. The procedure is as follows. The BIB-SEM image obtained by the above method was normalized to an average brightness of 100 and a standard deviation of ±30, and then binarized using a brightness threshold of 120. At this time, particles represented by white pixels are active material particles. The distribution of active material particles in the lamination direction of the resin substrate and particle layer in the particle layer on the resin substrate was obtained by counting the number of white pixels in each raster lined up in the z-axis direction. The position where the distribution of active material particles peaks in the particle layer on the resin substrate was used as the reference line of maldistribution. That is, a reference line perpendicular to the z-axis direction was drawn at the position where the distribution of active material particles peaks in the z-axis direction. An example of a BIB-SEM image and a peak in the distribution of active material particles is shown in FIG. 35 . FIG. 35 is a diagram showing a BIB-SEM image of a cross section of an electrode substrate laminate in which three electrode substrates are stacked. From the bottom of FIG. 35 (the base point side of the z-axis), three electrode substrates are stacked, each formed with a resin substrate and a particle layer in that order. The reference line is determined by identifying the position where the distribution of active material particles peaks in each electrode substrate. For example, in FIG. 35 , the dotted line at the position where the peak on the right (active material distribution) overlaps with the dotted line indicates the reference line.

[0236] <Method for Determining Maldistribution> Next, a method for determining the maldistribution of solid electrolyte particles in a BIB-SEM image will be described. Using the above-described method, solid electrolyte particles on the resin substrate were detected in an SEM image, and their equivalent circle diameters were calculated. From the distribution of the equivalent circle diameters of the primary particles of the obtained solid electrolyte particles, particles with a cumulative diameter of 10% or less on a number basis were extracted from the small particle size side, and second solid electrolyte particles were identified. For each of the identified second solid electrolyte particles, the shortest distance from the surface of the resin substrate in the z-axis direction was defined as the minimum value min, and the longest distance was defined as the maximum value max. The longest distance was the position of the farthest part of the second solid electrolyte particle from the surface of the resin substrate in the z-axis direction. The average of min and max was then determined as the central position of the second solid electrolyte particle, and this was defined as the position of the second solid electrolyte particle. For example, in FIG. 36 , 19 (the center of the circled area) shown in the figure is the central position of the second solid electrolyte particle, i.e., the particle position. The dashed line shown in the figure is the reference line determined by the above-described method.

[0237] In electron microscope images captured using the above-described method (images captured so that a total of 500 solid electrolyte particles were counted), the positions of the second solid electrolyte particles were compared with the reference line for uneven distribution. The particle positions of all second solid electrolyte particles in the five images were determined using the above-described method. Furthermore, a reference line was determined for each image using the above-described method. Next, in each image, it was confirmed whether 80% or more of the second solid electrolyte particles were located on the side contacting the resin substrate or on the opposite side of the reference line from the resin substrate. A single determination was made for all 500 second solid electrolyte particles in the five images. As described above, the positions of the second solid electrolyte particles were determined based on the center position of the particles. That is, if the center positions of 80% or more of the second solid electrolyte particles among the second solid electrolyte particles were located on the resin substrate side or the opposite side of the resin substrate from the reference line, the second solid electrolyte particles were determined to be unevenly distributed. For example, in FIG. 36 , it can be seen that 80% or more of the second solid electrolyte particles were located farther from the resin substrate than the reference line. When 80% or more by number of the identified second solid electrolyte particles are located on the resin substrate side or the opposite side to the resin substrate with respect to the reference line, the second solid electrolyte particles are determined to be unevenly distributed.

[0238] As described above, the electrode substrate can also be used as an electrode substrate laminate in which electrode substrates are stacked. That is, in an electrode substrate in which a particle layer is formed on a resin substrate, another resin substrate may be present on the particle layer. In this case, any one side of the particle layer can be set as the resin substrate side and the other side can be set as the opposite side to the resin substrate, and the uneven distribution can be determined by the above-mentioned method. In addition, in the present disclosure, the electrode substrate may be in a form in which a resin substrate, a particle layer, and a resin substrate are stacked in this order. In this case, as in the above, one side can be set as the resin substrate side and the other side can be set as the opposite side, and the uneven distribution can be determined by the above-mentioned method.

[0239] Electrodes (positive electrodes) were prepared from the electrode substrates of Example 1 and Comparative Examples 1 to 6, and all-solid-state batteries were assembled by the method described above. The results of evaluation of the rate characteristics and cycle characteristics of All-Solid-State Battery 1 manufactured using the electrode substrate of Example 1 and Comparative All-Solid-State Batteries 1 to 6 manufactured using the electrode substrates of Comparative Examples 1 to 6 are shown below. In the table, "AIR" indicates that sintering was performed in air. In the "compatibility" column, when both the rate characteristics and cycle characteristics were evaluated as A, it was marked with "O", and when not, it was marked with "X". As described above, only Example 1 was evaluated as A for both the rate characteristics and cycle characteristics, and it was confirmed that excellent ionic conductivity and mitigation of volume fluctuation could be achieved at the same time.

[0240] The methods for evaluating the rate characteristics and cycle characteristics are described below. <Rate characteristics> The mass M (g / cm) of the active material particles per unit area of ​​the electrode substrate was measured. ２ ) to calculate the active material particle mass of the electrode (M × number of layers × electrode area (cm ２)) is calculated to determine the current rate. The active material particle mass M per unit area is found as follows: The weight of the first substrate 11a is measured after the first particles P1 have been filled using the first filling device. Next, the weight of the first substrate 11a is measured after the particles P1 on the first substrate 11a have been transferred to the second substrate 11b. The difference is measured and divided by the area of ​​the first substrate 11a (area of ​​the concave-convex region) to calculate the active material particle mass M per unit area. In the present disclosure, the active material particle mass M per unit area is calculated using the above method. Another calculation method is to use ICP atomic emission spectroscopy. The active material particle mass M (g / cm) per unit area is calculated in advance using the above method or the like. ２ Three levels of first substrates 11a are prepared, with the Co element quantified. These first substrates 11a are dissolved by microwave acid decomposition (ETHOS PRO), and the acid decomposition solution is diluted with ultrapure water and subjected to ICP-AES measurement (CIROS CCD), and the Co element is quantified. The active material particle mass per unit area M (g / cm) relative to the obtained element concentration is calculated. ２ From the calibration curve, the active material particle mass M (g / cm ２ ) can be obtained. The actual capacity of the LCO was 120 mAh / g, and the cutoff voltage (vs. Li) was 4.2 V (charge) / 2.6 V (discharge). Using a charge / discharge device (manufactured by Biologic), charge / discharge measurements (constant current mode) were performed at each rate, and the capacity retention rate (discharge capacity / charge capacity x 100%) was measured. The maximum value R at the rate at which the capacity retention rate was 80% or higher was determined, and evaluated according to the following evaluation criteria: A: R≧0.4C B: 0.4C>R≧0.3C C: 0.3C>R

[0241] <Cycle Characteristics> Cycle evaluation (repeated charge / discharge measurement in constant current mode) was performed at the rate R obtained in the rate characteristic evaluation. The charge / discharge measurement was repeated until the capacity was 80% or less of the initial capacity retention rate, and the number of times n was calculated and evaluated according to the following evaluation criteria: A: n≧10 B: 10>n≧5 C: 5>n

[0242] It was determined that both excellent ion conductivity and mitigation of volume fluctuation were achieved when the evaluations of the rate characteristics and cycle characteristics were both A. As a result, only Example 1 was evaluated as A in both the rate characteristics and cycle characteristics, and it was confirmed that both excellent ion conductivity and mitigation of volume fluctuation were achieved.

[0243] FIG. 26 is a BIB-SEM image of the cross section of an electrode manufactured using the electrode substrate 1 of Example 1. The substrate has been removed by sintering, and sintering of the particles is progressing. LCO, which is the first particle P1, LBO (product B2), which is the second particle P2, and LBO (product A2), which is the third particle P3, are arranged on the positive electrode current collector (Al foil) of the substrate 14, and voids can be seen around the LCO. Furthermore, the voids are unevenly distributed on the substrate 14 side of the LCO particles (the side of the resin substrate before the substrate is removed). This is achieved by the particle arrangement on the substrate.

[0244] FIG. 27 is a schematic diagram of an electrode substrate manufactured using the electrode substrate 1 of Example 1. For the sake of explanation, particles P1, P2, and P3 are depicted as spherical and having the same particle size. As described above, in the electrode substrate 11 of Example 1, particle P3 is unevenly distributed on the side opposite the resin substrate side, forming a dense region. On the other hand, on the substrate side, voids (e.g., the SP portion in FIG. 27) are uniformly distributed between particles P1 and P2. Even when the substrate is removed by sintering, the dense regions and uniform voids of each substrate are maintained, and it is believed that the structure shown in FIG. 27 is realized.

[0245] In the electrode manufactured using the electrode substrate 1 of Example 1, voids are provided around the active material particles, and the voids are unevenly distributed on the current collector 14 side, which serves as the substrate, in the particle layer containing the active material particles and the solid electrolyte particles. Furthermore, a dense region is formed on the side of the particle layer opposite the current collector side. This is thought to be why both ion conduction within the electrode and mitigation of volume fluctuations of the active material particles can be achieved.

[0246] Figure 28 is a BIB-SEM image of the cross section of an electrode manufactured using electrode substrate 3 of Comparative Example 2. No voids around the LCO as in Figure 26 (Example 1) are observed. Figure 29 is a BIB-SEM image of the cross section of an electrode manufactured using electrode substrate 6 of Comparative Example 5. Although voids can be observed around the LCO, there are many voids throughout the particle layer, and the density is low.

[0247] <Method for manufacturing electrode substrates 9 to 13> Electrode substrates 9 to 13 were obtained by forming particle layers 9 to 13 under the same conditions as for particle layer 1, except that the type of second particles P2, the type of third particles P3, and the pitch s of the convex portions of the concave-convex pattern 111a on the first substrate 11a were changed as shown in Table 5. The obtained electrode substrates 9 to 13 were designated Examples 2 to 6. Table 5 shows the fillers 241a, 241b, and 241c used in Examples 1 to 6 and the concave-convex pattern 111a on the first substrate 11a. The support material S1 in filler 241a, the support material S2 in filler 241b, and the support material S3 in filler 241c were all the same as the standard carriers described above. In the table, the mass % of particles indicates the mass % of each particle in each filler.

[0248] Table 6 shows the particle size of each particle in the filler used in Examples 1-6. The standard carriers used as the support materials S1, S2 and S3 had r10 of 60 μm, r50 of 81 μm and r90 of 113 μm.

[0249] Table 7 shows the evaluation results of Examples 1 to 6.

[0250] Electrodes (cathode) were prepared from the electrode substrates of Examples 1 to 6, and all-solid-state batteries were assembled by the above-described method. Table 8 shows the evaluation results of the rate characteristics and cycle characteristics of all-solid-state batteries 1 to 6 prepared using the electrode substrates of Examples 1 to 6. In the table, "Ar-H ２ " refers to a reducing atmosphere (Ar-H ２ ) indicates that sintering was carried out under

[0251] In evaluating the rate characteristics and cycle characteristics of Examples 1 to 6, the actual capacity of each positive electrode active material was 120 mAh / g for LCO, 130 mAh / g for NMC, and 150 mAh / g for LFP. The cutoff voltages were 4.2 V / 2.6 V for LCO, 4.2 V / 2.6 V for NMC, and 3.8 V / 2.5 V for LFP.

[0252] Although a laminate in which three identical positive electrode substrates were stacked was used in Examples 1 to 6, a laminate in which multiple types of positive electrode substrates having the configuration of the present disclosure are stacked may also be used. In addition, the electrode substrate may be used as a material for a coating process (including a multilayer capacitor (MLCC) manufacturing technique) or a powder pressurization process, which are conventionally known manufacturing methods.

[0253] 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 invention. Therefore, the following claims are appended to clarify the scope of the present disclosure. This application claims priority based on Japanese Patent Application No. 2023-097669, filed on June 14, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. An electrode base material used in the manufacture of an electrode, the electrode base material comprising a resin base material, and active material particles and solid electrolyte particles on the resin base material, a particle layer comprising the active material particles and the solid electrolyte particles is formed on the resin base material, wherein when an average equivalent circular diameter ra of the active material particles is a number-based cumulative 50% particle diameter calculated from a distribution of equivalent circular diameters of primary particles of the active material particles, and an average equivalent circular diameter re of the solid electrolyte particles is a number-based cumulative 50% particle diameter calculated from the distribution of equivalent circular diameters of primary particles of the solid electrolyte particles, a ratio (re / ra) of the average equivalent circular diameter re to the average equivalent circular diameter ra is 0.01 or more and 2.0 or less, and among the solid electrolyte particles, when particles having a particle diameter exceeding a cumulative 10% particle diameter on a number basis from the small particle diameter side in the distribution of equivalent circular diameters of primary particles of the solid electrolyte particles are referred to as first solid electrolyte particles, and particles having a cumulative 10% particle diameter or less are referred to as second solid electrolyte particles, in the particle layer the active material particles and the first solid electrolyte particles are disposed adjacent to each other, and in a cross-sectional observation of the particle layer, 80% or more by number of the second solid electrolyte particles are disposed unevenly on a side of the particle layer in contact with the resin substrate or on an opposite side to the resin substrate with respect to a reference line, the reference line indicating a peak position of a distribution of the active material particles in the particle layer in a stacking direction of the resin substrate and the particle layer.

2. The electrode substrate according to claim 1, wherein the first solid electrolyte particles include Li-B oxide-based electrolyte particles, and the active material particles include Li-Co oxide-based active material particles.

3. The electrode substrate according to claim 1 or 2, wherein the second solid electrolyte particles include Li-B oxide-based electrolyte particles.

4. The first solid electrolyte particles include Li-B oxide-based electrolyte particles, and the active material particles include Li-PO ４ The electrode substrate according to claim 1 , comprising oxide-based active material particles.

5. The electrode substrate according to claim 1 or 4, wherein the second solid electrolyte particles include Li-B oxide-based electrolyte particles.

6. The electrode substrate according to any one of claims 1 to 5, wherein a coverage rate of the surface of the resin substrate by the active material particles and the solid electrolyte particles is 60% or more and 99% or less.

7. An electrode substrate laminate comprising a plurality of electrode substrates according to any one of claims 1 to 6 laminated together.

8. An electrode substrate laminate according to claim 7, wherein the resin substrate and the particle layer are present alternately in a cross section of the electrode substrate laminate.

9. An electrode for a secondary battery, the electrode being a sintered body of the electrode substrate according to any one of claims 1 to 6.

10. The electrode according to claim 9, wherein the solid electrolyte particles comprise Li-B oxide based solid electrolyte particles, and the active material particles comprise Li-Co oxide based active material particles.

11. A secondary battery comprising the electrode according to claim 9 or 10 and an electrolyte layer adjacent to said electrode.

12. A manufacturing method for an electrode substrate according to any one of claims 1 to 6 used in the manufacture of an electrode, the manufacturing method comprising the steps of: preparing the resin substrate having an adhesive portion; arranging the active material particles and the first solid electrolyte particles on a surface of the adhesive portion; a particle precipitation step of precipitating the first solid electrolyte particles and the active material particles arranged on the surface of the adhesive portion into the adhesive portion; and arranging second solid electrolyte particles in the adhesive portion between the settled first electrolyte particles and the active material particles.

13. A method for producing an electrode base material used in the production of an electrode, the electrode base material comprising active material particles and solid electrolyte particles on a resin base material, a particle layer comprising the active material particles and the solid electrolyte particles formed on the resin base material, a number-based cumulative 50% particle diameter calculated from a distribution of equivalent circular diameters of primary particles of the active material particles is defined as an average equivalent circular diameter ra of the active material particles, and a number-based cumulative 50% particle diameter calculated from the distribution of equivalent circular diameters of primary particles of the solid electrolyte particles is defined as an average equivalent circular diameter re of the solid electrolyte particles, a ratio (re / ra) of the average equivalent circular diameter re to the average equivalent circular diameter ra is 0.01 or more and 2.0 or less, the solid electrolyte particles comprise solid electrolyte particles P2 and solid electrolyte particles P3, a cumulative 50% particle size (r50) in a volume-based particle size distribution of primary particles of the solid electrolyte particles P2 is larger than a cumulative 50% particle size (r50) in a volume-based particle size distribution of primary particles of the solid electrolyte particles P3, the manufacturing method comprising the steps of: preparing the resin substrate having an adhesive portion on a surface thereof; arranging the active material particles and the solid electrolyte particles P2 adjacent to each other on the surface of the adhesive portion; a particle precipitation step of settling the solid electrolyte particles P2 and the active material particles arranged on the surface of the adhesive portion into the adhesive portion; and arranging the solid electrolyte particles P3 in the adhesive portion between the settled solid electrolyte particles P2 and the active material particles.

14. A method for manufacturing an electrode, comprising the steps of: laminating a plurality of electrode substrates according to any one of claims 1 to 6 to form a laminate; removing the resin substrate from the laminate to obtain a three-dimensional object; and applying pressure to the three-dimensional object to obtain an electrode.

15. A method for manufacturing a secondary battery, comprising the steps of: preparing an electrode by the electrode manufacturing method according to claim 14; and laminating the electrode, a current collector, and an electrolyte.

16. A method for manufacturing a secondary battery, comprising the steps of: preparing an electrode by the electrode manufacturing method according to claim 14; and providing a solid electrolyte adjacent to the electrode.

17. A method for producing a secondary battery, comprising the step of providing, together, the electrode according to claim 9 or 10 and a solid electrolyte adjacent to the electrode.

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