Electrode, electrode composite body, secondary battery, and method for manufacturing electrode

Abstract

Disclosed is an electrode which is to be applied to a secondary battery, the electrode including active material particles and a conductive resin. The active material particles each have an inner surface, and the conductive resin is positioned so as to be in contact with the inner surface.

Description

Electrode, electrode composite, secondary battery, and method for manufacturing electrode

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

[0002] Generally, secondary batteries consist of electrodes (positive and negative electrodes) and an electrolyte. Charging and discharging occur through the transfer of ions between the electrodes via the electrolyte. These 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 improvements in secondary battery performance are required. In recent years, research and development of so-called all-solid-state batteries, which use inorganic solid electrolytes as the electrolyte, has progressed. By replacing conventional organic electrolytes with solid electrolytes, all-solid-state batteries are expected to improve safety and increase capacity and power output. However, in all-solid-state batteries, the expansion and contraction of active material particles during the ion intercalation and deintercalation process in the electrode can easily disrupt contact between the electrolyte and active material particles. This disrupts the intercalation and deintercalation of ions, such as lithium ions, into the active material particles, increasing the electrode resistance and significantly reducing the charge / discharge current, or so-called output characteristics. To address this issue, a technique has been developed that incorporates lithium ion conductive polymers, which are more flexible than electrolyte particles, into the electrode. Patent Document 1 discloses an electrode in which the outer surfaces of active material particles are partially coated with a lithium ion conductive polymer.

[0003] JP 2002-373643 A JP 2020-198301 A

[0004] However, the present inventors have found that simply partially coating the outer surfaces of active material particles with a polymer is insufficient to improve the diffusibility of lithium ions within an electrode. This is believed to be due to the following reasons: Active material particles within an electrode expand and contract during charge and discharge. Adjacent active material particles also expand and contract similarly. Therefore, simply partially coating the outer surfaces of active material particles with a polymer easily blocks the lithium ion diffusion pathways formed by the polymer between active material particles and the electrolyte particles. Furthermore, in the active material particles of Patent Document 1, the surfaces of the active material particles are partially coated with both polymer and electrolyte particles. Therefore, contact between the polymer and the electrolyte particles is also limited, and the expansion and contraction of the active material particles easily blocks this contact. Therefore, lithium ion diffusion is easily restricted between the active material particles and the polymer. As a result, even solid electrolytes, which generally have higher ionic conductivity than polymers, tend to have a reduced ion diffusion effect.

[0005] Furthermore, Patent Document 1 discloses methods for partially coating the surfaces of active material particles, such as mechanical milling and chemical coating treatment. However, these treatment methods have difficulty in achieving a uniform coating area and thickness for each particle, and there is also a problem with reproducibility as an electrode manufacturing method.

[0006] The present disclosure provides an electrode that can mitigate expansion and contraction of active material particles and suppress a decrease in battery output when used in a secondary battery. The present disclosure also provides an electrode composite including the electrode of the present disclosure. In addition, the present disclosure provides a secondary battery in which a decrease in battery output is suppressed. Furthermore, the present disclosure provides a method for producing an electrode with high reproducibility.

[0007] An electrode according to one aspect of the present disclosure is an electrode for use in a secondary battery, the electrode comprising active material particles and a conductive resin, the active material particles having an inner surface, and the conductive resin being positioned so as to be in contact with the inner surface.

[0008] An electrode composite according to one aspect of the present disclosure includes an electrode and an electrolyte layer that transfers an active material between the electrode and the electrolyte layer, wherein the electrode is the electrode of the present disclosure.

[0009] A secondary battery according to one aspect of the present disclosure includes a positive electrode and an electrolyte layer that transfers an active material between the positive electrode and the electrolyte layer, wherein the positive electrode is the electrode according to any one of claims 1 to 22, and the secondary battery includes a negative electrode that transfers the active material between the negative electrode and the electrolyte layer.

[0010] A method for manufacturing an electrode according to one aspect of the present disclosure is characterized by comprising: a 1-1 step of preparing an electrode precursor that includes active material particles and has gaps between the active material particles; a 2-1 step of preparing a filler material to be filled into the electrode precursor; a 3-1 step of filling the filler material from the outside to the inside of the electrode precursor; and a 4-1 step of retaining the filler material filled inside the electrode precursor.

[0011] According to the present disclosure, it is possible to provide an electrode that can mitigate expansion and contraction of active material particles and suppress a decrease in battery output characteristics when used in a secondary battery. The present disclosure also provides an electrode composite including the electrode of the present disclosure. Furthermore, the present disclosure can provide a secondary battery in which a decrease in battery output is suppressed. In addition, the present disclosure can provide a method for manufacturing an electrode with high reproducibility.

[0012] 1 is an image diagram showing a method for manufacturing an electrode precursor. FIG. 1 is a diagram schematically showing the configuration of a particle arrangement device 1. FIG. 1 is a diagram schematically showing the configuration of a filling device. FIG. 1 is a diagram of a filler being transported on a first substrate. FIG. 2 is an enlarged view of the vicinity of the surface of a first substrate. FIG. 2 is a diagram schematically showing the configuration of a filling device when brush fibers are used as a support material. FIG. 3 is a diagram schematically showing the configuration of a transfer unit. FIG. 4 is an enlarged view of the vicinity of the surface of a second substrate in a filling process using a second filling device. FIG. 5 is a diagram schematically showing the second substrate after the first particles P1 and the second particles P2 have been transferred. FIG. 6 is a diagram schematically showing the configuration of a particle arrangement device 2. FIG. 7 is a diagram schematically showing the configuration of a laminate molding device. FIG. 8 is a diagram schematically showing the configuration of a sintering treatment device. SEM images of a laminate and a three-dimensional object in each step of a method for manufacturing an electrode. BIB-SEM image of a three-dimensional object according to an embodiment of the present disclosure. An explanatory diagram of the mechanism related to a three-dimensional object according to an embodiment of the present disclosure. FIG. 9 is a diagram showing the results of thermogravimetry measurement of a resin substrate. FIG. 10 is a diagram showing the results of thermogravimetry and mass spectrometry measurement. FIG. 11 is a diagram showing LCO particles after a third step. 1 is a diagram showing the results of STEM-EDX on LCO particles after the third step. 2 is an image diagram showing a method for manufacturing an electrode. 3 is a schematic diagram showing one embodiment of the third step. 4 is a diagram showing charge / discharge curves of a secondary battery. 5 is a diagram showing an electron microscope image of a cross section of a positive electrode. 6 is a diagram showing a low-magnification electron microscope image of a cross section of a positive electrode. 7 is a schematic diagram showing features of the present disclosure. 8 is a diagram showing an electron microscope image of a cross section of a positive electrode.

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

[0014] As a result of investigations by the present inventors, it was found that it is important to place a conductive resin (polymer) at an appropriate position relative to the active material particles in the electrode. This makes it easier to mitigate the expansion and contraction of each active material particle inside the electrode while suppressing a decrease in ion diffusion within the electrode. In the present disclosure, the electrode of the present disclosure is realized by filling an electrode precursor with a polymer and retaining it inside the electrode precursor using the method described below. In the present disclosure, the mitigation of expansion and contraction of each active material particle 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.

[0015] The electrode of the present disclosure is an electrode for use in a secondary battery. The electrode includes active material particles and a conductive resin. By including the active material particles and the conductive resin in the electrode, ions can be transferred between the electrodes via an electrolyte, allowing the electrode to be used as an electrode.

[0016] Preferably, the active material particles have an inner surface, and the conductive resin is positioned so as to contact the inner surface of the active material particles. Here, the "inner surface" refers to the surface present inside the active material particles. In this way, by having the conductive resin contact the inner surface of the active material particles, the flexibility of the conductive resin alleviates the expansion and contraction of the active material particles, making it easier to suppress a decrease in ion diffusion within the electrode, thereby suppressing a decrease in output characteristics. For example, by performing a sintering treatment as in the third step described below, the active material particles can be made to have an inner surface within the particles. Furthermore, for example, by filling the electrode precursor with a filler material as in the third step described below, the conductive resin can be positioned so as to contact the inner surface of the active material particles. The fact that the active material particles have an inner surface within the particles can be confirmed by the measurement method described below. Furthermore, the fact that the conductive resin is positioned so as to contact the inner surface of the active material particles can be confirmed by the measurement method described below.

[0017] The inner surface of the active material particle preferably forms an internal pore (hereinafter also referred to as a communicating pore) that communicates with the outer surface of the active material particle. By forming such an internal pore, it becomes easier to position the filler material so that it contacts the inner surface of the active material particle during the step 3-1 described below. One method for forming such an internal pore is, for example, performing a sintering treatment as in the step 3 described below. Furthermore, the formation of such an internal pore on the inner surface of the active material particle can be confirmed by the measurement method described below.

[0018] Furthermore, it is preferable that the inner surface of the active material particle is continuous with the outer surface of the active material particle. By having the inner surface continuous with the outer surface, it becomes easier to position the conductive resin so that it contacts the inner surface of the active material particle during the step 3-1 described below. Furthermore, examples of active material particles having such an inner surface include active material particles having a core portion and a shell portion. Examples of methods for forming such an inner surface include performing a sintering treatment as in the step 3 described below.

[0019] Preferably, the active material particles have an outer surface, and the conductive resin is disposed in contact with the outer surface of the active material particles and connects the active material particles. Here, the outer surface refers to the surface that exists on the outside of the active material particles. In this way, the conductive resin is disposed in contact with the outer surface of the active material particles and connects the active material particles. By disposing the conductive resin in contact with the outer surface of the active material particles and connecting the active material particles, the flexibility of the conductive resin can mitigate the expansion and contraction of the active material particles while making it easier to suppress a decrease in ion diffusion within the electrode. As a result, a decrease in output characteristics can be suppressed. For example, by filling the electrode precursor with a filler material as in step 3-1 described below, the conductive resin can be disposed in contact with the outer surface of the active material particles and connect the active material particles. The fact that the conductive resin is disposed in contact with the outer surface of the active material particles and connects the active material particles can be confirmed by the measurement method described below.

[0020] The active material particles preferably have protrusions. The shape of the protrusions is not particularly limited, and examples thereof include whiskers, which are beard-like, and dendrites, which are dendritic. Examples of the protrusions include those protruding from the outer surface. Having such protrusions increases the surface area of ​​the active material particles. As a result, when the electrode contains an electrolyte, the contact area with the electrolyte can be increased. The protrusions can be formed, for example, by performing a sintering process, as in the third step described below. The presence of protrusions in the active material particles can be confirmed by observing the cross section of the electrode, which will be described later.

[0021] 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 (lithium cobalt oxide), LiMO ２ (M is an element selected from the group consisting of Ni, Mn, and Co), ４ Oxide-based active material particles, lithium vanadium compounds (Li ３ V ２ (P.O. ４ ) ３ , LiVOPO ４ ), olivine-type phosphate compounds (LiMPO ４ (M is one or more elements selected from the group consisting of Co, Ni, Mn, Fe, Mg, V, Nb, Ti, Al, and Zr). Active material particles that do not contain lithium may also be used. Specifically, for example, metal oxides (MnO ２ , V ２ O ５ etc.) and fluorides (FeF ３ , V.F. ３ When using active material particles that do not contain lithium, metallic lithium containing lithium or a negative electrode active material doped with lithium ions is placed as the negative electrode active material, and the negative electrode active material can be used by starting discharge. In addition, graphite, Si, lithium titanate (LTO), etc. can also be used as negative electrode active material particles.

[0022] The present inventors have clarified that, among the above 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, thereby improving the output characteristics of the secondary battery (Patent Document 2). ４ Oxide-based active material particles are very stable because the covalent bond between P—O is strong and oxygen release is suppressed. Therefore, among the above positive electrode active material particles, Li—Co oxide-based active material particles, Li—PO ４ It is preferable that the active material contains oxide-based particles.

[0023] The active material particles may be commercially available products or may be separately prepared as materials. 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 As oxide-based active material particles, Li ３ V ２ (P.O. ４ ) ３ (Tokyo Chemical Industry Co., Ltd.) and LiFePO ４ (manufactured by Toshima Manufacturing Co., Ltd.) can be used. ３ V ２ (P.O. ４ ) ３ and LiFePO 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.

[0024] The electrode preferably contains at least one selected from the group consisting of a conductive resin, a conductive additive, and a supporting electrolyte between the active material particles, and more preferably contains a conductive resin and a supporting electrolyte between the active material particles. This improves the diffusibility of lithium ions within the electrode and reduces electrode resistance. Furthermore, the actual capacity of the battery can be improved by reducing isolated active material particles that cannot exchange lithium ions within the electrode. The fact that the electrode contains at least one selected from the group consisting of a conductive resin, a conductive additive, and a supporting electrolyte between the active material particles can be confirmed by the results of element mapping in the cross-sectional observation described below.

[0025] The conductive resin is not particularly limited, and any known resin can be used as long as it is conductive. For example, the conductive resin may be a resin with ionic conductivity. Examples of the conductive resin include gel electrolytes and dry polymer electrolytes. From the viewpoint of safety, dry polymer electrolytes that do not contain flammable electrolytes are preferred. The conductive resin preferably contains at least one of polyurethane, polyacrylic, and polyether in its main chain structure. Polyether, urethane resin containing polyether, and acrylic resin containing polyether are more preferred, and urethane resin containing polyether is even more preferred. Furthermore, a copolymer of polyethylene glycol and polypropylene glycol is preferred as the polyether. The conductive resin preferably contains an ionic functional group such as a cation structure in its structure to achieve conductivity. The conductive resin preferably contains an anion. Furthermore, the conductive resin may be conductive by containing a conductive assistant or a supporting electrolyte.

[0026] The ionic group is preferably at least one cationic structure selected from the group consisting of a cationic nitrogen-containing heterocyclic structure and an ammonium cation having a linear or branched structure. The cationic nitrogen-containing heterocyclic structure is not particularly limited, but may be a four- to eight-membered ring. Examples of the cationic nitrogen-containing heterocyclic structure include cationic nitrogen-containing aromatic heterocyclic structures such as imidazolium cation, pyridinium cation, pyrazinium cation, pyrimidinium cation, azepinium cation, quinolinium cation, isoquinolinium cation, indolinium cation, quinoxalinium cation, triazolium cation, triazinium cation, and thiazolinium cation; and cationic nitrogen-containing aliphatic heterocyclic structures such as pyrrolidinium cation, pyrrolinium cation, imidazolinium cation, imidazolidinium cation, piperazinium cation, azepanium cation, diazepanium cation such as 1,3-diazepanium cation and 1,4-diazepanium cation, azocanium cation, oxazolinium cation, and morpholinium cation. Among these, the cationic nitrogen-containing aromatic heterocyclic structure is preferably at least one selected from the group consisting of imidazolium cation, pyridinium cation, and pyrazinium cation, and more preferably an imidazolium cation. The cationic nitrogen-containing aliphatic heterocyclic structure is preferably at least one selected from the group consisting of a pyrrolidinium cation and a piperazinium cation, and more preferably a pyrrolidinium cation.

[0027] Examples of ammonium cations having a linear or branched structure include primary ammonium cations, secondary ammonium cations, tertiary ammonium cations, and quaternary ammonium cations, with quaternary ammonium cations being preferred. The hydrocarbon group possessed by the ammonium cation is not particularly limited, and may, for example, have a hydrocarbon group having 1 to 8 carbon atoms (preferably 1 to 4, more preferably 1 to 2, and even more preferably 1). Furthermore, ammonium cations having a linear or branched structure may have a structure represented by the following formula (4). The cationic structure may have any substituent, such as a hydrocarbon group. For example, the cationic structure preferably includes at least one structure selected from the group consisting of structures represented by the following formulas (1) to (6). Each of the structures represented by formulas (1) to (6) will be described below.

[0028] The structure represented by formula (1) will be described below. In formula (1), R １ and R ２ represents a hydrocarbon group that forms a five-membered nitrogen-containing aromatic heterocyclic structure together with the nitrogen atom to which it is bonded, Z １ ~Z ３ each independently represents a structure represented by the following formula (X), a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1), or a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1) and a hydroxyl group, and Z １ ~Z ３ At least one of the above is a structure represented by the following formula (X), １ represents an integer of 0 to 3 (preferably 0 or 1).

[0029] The hydrocarbon group having 1 to 4 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 2 carbon atoms, and even more preferably an alkyl group having 1 carbon atom. The hydrocarbon group having 1 to 4 carbon atoms and having a hydroxyl group is preferably a hydroxyalkyl group having 1 to 4 carbon atoms, more preferably a hydroxyalkyl group having 1 to 2 carbon atoms, and even more preferably a hydroxyalkyl group having 1 carbon atom. The hydrocarbon group may also have two or more hydroxyl groups. The structure represented by formula (1) represents a cation of a five-membered nitrogen-containing aromatic heterocyclic structure having at least one structure represented by the following formula (X) and two nitrogen atoms. The nitrogen-containing aromatic heterocyclic structure in formula (1) is preferably, for example, an imidazolium cation. The method for incorporating the structure represented by formula (1) into the structure of a conductive resin is not particularly limited. For example, when the conductive resin is a urethane resin, at least one structure represented by formula (1) is incorporated into the structure of the urethane resin by reacting an ionic compound having a structure corresponding to the cation of the five-membered nitrogen-containing aromatic heterocyclic structure represented by formula (1) with an isocyanate compound.

[0030] As the five-membered nitrogen-containing aromatic heterocyclic structure in formula (1), the cationic nitrogen-containing aromatic heterocyclic structure described in the above-mentioned cation structure column can be used, and among them, imidazolium cation is preferred. Examples of ionic compounds having a structure corresponding to the cation of the five-membered nitrogen-containing aromatic heterocyclic structure in formula (1) include Z １ ~Z ３ and n is a hydroxyl group, and n is a divalent hydrocarbon having a straight chain or a branched chain. As an example of this ionic compound, an ionic compound containing an imidazolium cation is given below.

[0031] 1-methyl-3-hydroxymethylimidazolium cation, 1-methyl-3-(2-hydroxyethyl)imidazolium cation, 1-methyl-3-(3-hydroxypropyl)imidazolium cation, 1-methyl-3-(4-hydroxybutyl)imidazolium cation, 1-ethyl-3-(2-hydroxyethyl)imidazolium cation, 1-n-butyl-3-(2-hydroxyethyl)imidazolium cation, 1,3-dimethyl-2-(2-hydroxyethyl)imidazolium cation, 1,3-dimethyl-2-(4-hydroxybutyl)imidazolium cation, 1,3-dimethyl-4-(2-hydroxyethyl)imidazolium cation; 1,3-bishydroxymethylimidazolium cation, 1,3-bis(2-hydroxyethyl)imidazolium cation, 2-methyl-1,3-bishydroxymethylimidazolium cation, 2-methyl-1,3-bis(2-hydroxyethyl)imidazolium cation, 4-methyl-1,3-bis(2-hydroxyethyl)imidazolium cation, 2-ethyl-1,3-bis(2-hydroxyethyl)imidazolium cation, 4-ethyl-1,3-bis(2-hydroxyethyl)imidazolium cation, 2-n-butyl 1,3-bis(2-hydroxyethyl)imidazolium cation, 4-n-butyl-1,3-bis(2-hydroxyethyl)imidazolium cation, 1,3-bis(3-hydroxypropyl)imidazolium cation, 1,3-bis(4-hydroxybutyl)imidazolium cation, 1-methyl-2,3-bis(2-hydroxyethyl)imidazolium cation, 1-methyl-3,4-bis(2-hydroxyethyl)imidazolium cation, 1-methyl-3,5-bis(2-hydroxyethyl)imidazolium cation;1,2,3-trishydroxymethylimidazolium cation, 1,2,3-tris(2-hydroxyethyl)imidazolium cation, 1,2,3-tris(3-hydroxypropyl)imidazolium cation, 1,2,3-tris(4-hydroxybutyl)imidazolium cation, 1,3,4-trishydroxymethylimidazolium cation, 1,3,4-tris(2-hydroxyethyl)imidazolium cation, 1,3,4-tris(3-hydroxypropyl)imidazolium cation, 1,3,4-tris(4-hydroxybutyl)imidazolium cation; and derivatives thereof;

[0032] The structure represented by formula (2) will be described below. In formula (2), R ３ represents a hydrocarbon group that forms a nitrogen-containing aromatic heterocyclic structure together with the nitrogen atom to which it is bonded; Z ４ and Z ５ each independently represents a structure represented by formula (X), a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1), or a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1) and a hydroxyl group, Z ４ and Z ５ At least one of the groups is a structure represented by formula (X), and d ２ represents an integer of 0 to 5 (preferably 0 or 1).

[0033] The hydrocarbon group having 1 to 4 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 2 carbon atoms, and even more preferably an alkyl group having 1 carbon atom. The hydrocarbon group having 1 to 4 carbon atoms and having a hydroxyl group is preferably a hydroxyalkyl group having 1 to 4 carbon atoms, more preferably a hydroxyalkyl group having 1 to 2 carbon atoms, and even more preferably a hydroxyalkyl group having 1 carbon atom. The hydrocarbon group may have two or more hydroxyl groups. The structure represented by formula (2) represents a cation of a nitrogen-containing aromatic heterocyclic structure having at least one structure represented by the following formula (X). The nitrogen-containing aromatic heterocyclic structure in formula (2) may be a five- to eight-membered ring, and is preferably a five- or six-membered ring. The nitrogen-containing aromatic heterocyclic structure in formula (2) is preferably, for example, a pyridinium cation. There are no particular limitations on the method for incorporating the structure represented by formula (2) into the structure of a conductive resin. For example, when the conductive resin is a urethane resin, at least one structure represented by formula (2) is incorporated into the structure of the urethane resin by reacting an ionic compound having a structure corresponding to the cation of the nitrogen-containing aromatic heterocyclic structure represented by formula (2) with an isocyanate group.

[0034] As the nitrogen-containing aromatic heterocyclic structure in formula (2), the cationic nitrogen-containing aromatic heterocyclic structure described in the above cation structure column can be used, and among them, a pyridinium cation is preferred. Examples of ionic compounds having a structure corresponding to the cation of the nitrogen-containing aromatic heterocyclic structure in formula (2) include Z ４ and Z ５ and n is 0 or 1. At least one of the groups is a divalent hydrocarbon having a hydroxyl group and having a straight chain or branched chain. As an example of this ionic compound, an ionic compound containing a pyridinium cation is given below.

[0035] 1-hydroxymethylpyridinium cation, 1-(2-hydroxyethyl)pyridinium cation, 1-(3-hydroxypropyl)pyridinium cation, 1-(4-hydroxybutyl)pyridinium cation, 2-methyl-1-(2-hydroxyethyl)pyridinium cation, 3-methyl-1-(2-hydroxyethyl)pyridinium cation, 4-methyl-1-(2-hydroxyethyl)pyridinium cation, 3-ethyl-1-(2-hydroxyethyl)pyridinium cation, 3-n-butyl-1-(2-hydroxyethyl)pyridinium cation, 1-methyl-2-hydroxy hydroxymethylpyridinium cation, 1-methyl-3-hydroxymethylpyridinium cation, 1-methyl-4-hydroxymethylpyridinium cation, 1-methyl-2-(2-hydroxyethyl)pyridinium cation, 1-methyl-3-(2-hydroxyethyl)pyridinium cation, 1-methyl-4-(2-hydroxyethyl)pyridinium cation, 1-ethyl-3-(2-hydroxyethyl)pyridinium cation, 1-n-butyl-3-(2-hydroxyethyl)pyridinium cation, 2-methyl-4-n-butyl-1-(2-hydroxyethyl)pyridinium cation;1,2-bishydroxymethylpyridinium cation, 1,3-bishydroxymethylpyridinium cation, 1,4-bishydroxymethylpyridinium cation, 1,2-bis(2-hydroxyethyl)pyridinium cation, 1,3-bis(2-hydroxyethyl)pyridinium cation, 1,4-bis(2-hydroxyethyl)pyridinium cation, 1,2-bis(3-hydroxypropyl)pyridinium cation, 1,2-bis(3-hydroxypropyl)pyridinium cation, 1,3-bis(3-hydroxypropyl)pyridinium cation, 1, 4-bis(3-hydroxypropyl)pyridinium cation, 1,2-bis(4-hydroxybutyl)pyridinium cation, 1,3-bis(4-hydroxybutyl)pyridinium cation, 1,4-bis(4-hydroxybutyl)pyridinium cation, 2-methyl-1,3-bis(2-hydroxyethyl)pyridinium cation, 2-ethyl-1,3-bis(2-hydroxyethyl)pyridinium cation, 5-methyl-1,3-bis(2-hydroxyethyl)pyridinium cation, 5-ethyl-1,3-bis(2-hydroxyethyl)pyridinium cation; 1,2,4-trishydroxymethylpyridinium cation, 1,2,4-tris(2-hydroxyethyl)pyridinium cation, 1,2,4-tris(3-hydroxypropyl)pyridinium cation, 1,2,4-tris(4-hydroxybutyl)pyridinium cation, 1,3,5-trishydroxymethylpyridinium cation, 1,3,5-tris(2-hydroxyethyl)pyridinium cation, 1,3,5-tris(3-hydroxypropyl)pyridinium cation, 1,3,5-tris(4-hydroxybutyl)pyridinium cation; and derivatives thereof.

[0036] The structure represented by formula (3) will be described below. In formula (3), R ４ and R ５ represents a hydrocarbon group that forms a six-membered nitrogen-containing aromatic heterocyclic structure together with the nitrogen atom to which it is bonded, Z ６ and Z ７each independently represents a structure represented by the following formula (X), a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1), or a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1) and a hydroxyl group, and Z ６ and Z ７ At least one of the above is a structure represented by the following formula (X), ３ represents an integer of 0 to 4 (preferably 0 to 2).

[0037] The hydrocarbon group having 1 to 4 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 2 carbon atoms, and even more preferably an alkyl group having 1 carbon atom. The hydrocarbon group having 1 to 4 carbon atoms and having a hydroxyl group is preferably a hydroxyalkyl group having 1 to 4 carbon atoms, more preferably a hydroxyalkyl group having 1 to 2 carbon atoms, and even more preferably a hydroxyalkyl group having 1 carbon atom. The hydrocarbon group may also have two or more hydroxyl groups. The structure represented by formula (3) represents a cation of a six-membered nitrogen-containing aromatic heterocyclic structure having at least one structure represented by the following formula (X) and two nitrogen atoms. The nitrogen-containing aromatic heterocyclic structure in formula (3) is preferably, for example, a pyrazinium cation. The method for incorporating the structure represented by formula (3) into the structure of a conductive resin is not particularly limited. For example, when the conductive resin is a urethane resin, at least one structure represented by formula (3) is incorporated into the structure of the urethane resin by reacting an ionic compound having a structure corresponding to the cation of the six-membered nitrogen-containing aromatic heterocyclic structure represented by formula (3) with an isocyanate compound.

[0038] As the six-membered nitrogen-containing aromatic heterocyclic structure in formula (3), the cationic nitrogen-containing aromatic heterocyclic structure described in the above-mentioned cation structure column can be used, and among them, pyrimidinium cation and pyrazinium cation are preferred. Examples of ionic compounds having a structure corresponding to the cation of the six-membered nitrogen-containing aromatic heterocyclic structure in formula (3) include Z ６ and Z ７and n is a hydroxyl group, and n is a divalent hydrocarbon having a straight chain or a branched chain. As an example of this ionic compound, an ionic compound containing a pyrimidium cation is given below.

[0039] 1,4-bis(2-hydroxyethyl)pyrimidinium cation, 1,5-bis(3-hydroxybutyl)pyrimidinium cation, 1-(4-hydroxybutyl)-4-(2-hydroxyethyl)pyrimidinium cation, 1,4-bis(2-hydroxyethyl)-2-methylpyrimidinium cation; and derivatives thereof.

[0040] The structure represented by formula (4) will be described below. In formula (4), R ７ represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2 carbon atoms); Z ８ ~Z １０ each independently represents a structure represented by the following formula (X), a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1), or a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1) and a hydroxyl group; Z ８ ~Z １０ At least one of the above has a structure represented by the following formula (X):

[0041] The hydrocarbon group having 1 to 4 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 2 carbon atoms, and even more preferably an alkyl group having 1 carbon atom. The hydrocarbon group having 1 to 4 carbon atoms and having a hydroxyl group is preferably a hydroxyalkyl group having 1 to 4 carbon atoms, more preferably a hydroxyalkyl group having 1 to 2 carbon atoms, and even more preferably a hydroxyalkyl group having 1 carbon atom. The hydrocarbon group may also have two or more hydroxyl groups. The structure represented by formula (4) represents at least one ammonium cation having a structure represented by formula (X) below. There are no particular limitations on the method for incorporating the structure represented by formula (4) into the structure of a conductive resin. For example, when the conductive resin is a urethane resin, at least one structure represented by formula (4) can be incorporated into the structure of the urethane resin by reacting an ionic compound having a structure corresponding to the ammonium cation represented by formula (4) with an isocyanate compound.

[0042] As the ammonium cation in formula (4), ammonium cations having a linear or branched structure as described in the above-mentioned cation structure column can be used, and among them, quaternary ammonium cations are preferred. Examples of ionic compounds having a structure corresponding to the ammonium cation in formula (4) include Z ８ ~Z １０ and n is a hydroxyl group, and n is a divalent hydrocarbon having a straight chain or a branched chain. Examples of such ionic compounds include ionic compounds containing a quaternary ammonium cation.

[0043] 2-hydroxyethyltrimethylammonium cation, 2-hydroxyethyltriethylammonium cation, 4-hydroxybutyltrimethylammonium cation, 4-hydroxybutyl-tri-n-butylammonium cation; bis(hydroxymethyl)dimethylammonium cation, bis(2-hydroxyethyl)dimethylammonium cation, bis(3-hydroxypropyl)dimethylammonium cation, bis(4-hydroxybutyl)dimethylammonium cation; tris(hydroxymethyl)methylammonium cation, tris(2-hydroxyethyl)methylammonium cation, tris(3-hydroxypropyl)methylammonium cation, tris(4-hydroxybutyl)methylammonium cation; and derivatives thereof.

[0044] The structure represented by formula (5) will be described below. In formula (5), R ８ and R ９ represents a hydrocarbon group that forms a nitrogen-containing aliphatic heterocyclic structure together with the nitrogen atom to which it is bonded, Z １１ ~Z １４ each independently represents a structure represented by the following formula (X), a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1), or a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1) and a hydroxyl group, and Z １１ ~Z １４ At least one of the above is a structure represented by the following formula (X), ４ represents an integer of 0 to 4 (preferably 0 to 2).

[0045] The hydrocarbon group having 1 to 4 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 2 carbon atoms, and even more preferably an alkyl group having 1 carbon atom. The hydrocarbon group having 1 to 4 carbon atoms and having a hydroxyl group is preferably a hydroxyalkyl group having 1 to 4 carbon atoms, more preferably a hydroxyalkyl group having 1 to 2 carbon atoms, and even more preferably a hydroxyalkyl group having 1 carbon atom. The hydrocarbon group may have two or more hydroxyl groups. The structure represented by formula (5) represents a cation of a nitrogen-containing aliphatic heterocyclic structure having at least one structure represented by the following formula (X) and two nitrogen atoms. The nitrogen-containing aliphatic heterocyclic structure in formula (5) may be a five- to eight-membered ring, and is preferably a five- or six-membered ring. The nitrogen-containing aliphatic heterocyclic structure in formula (5) is preferably, for example, a piperazinium cation. There are no particular limitations on the method for incorporating the structure represented by formula (5) into the structure of a conductive resin. For example, when the conductive resin is a urethane resin, at least one structure represented by formula (5) is incorporated into the structure of the urethane resin by reacting an ionic compound having a structure corresponding to the cation of the nitrogen-containing aliphatic heterocyclic structure represented by formula (5) with an isocyanate compound.

[0046] As the nitrogen-containing aliphatic heterocyclic structure in formula (5), the cationic nitrogen-containing aliphatic heterocyclic structure described in the above cation structure column can be used, and among them, piperazinium cation is preferred. Examples of ionic compounds having a structure corresponding to the cation of the nitrogen-containing aliphatic heterocyclic structure in formula (5) include Z １１ ~Z １４ and n is a hydroxyl group, and n is a divalent hydrocarbon having a straight chain or a branched chain. As an example of this ionic compound, an ionic compound containing a piperazinium cation is given below.

[0047] 1,1-bis(2-hydroxyethyl)piperazinium cation, 1,1,4-tris(2-hydroxyethyl)piperazinium cation, 1,4-bis(3-hydroxypropyl)-1-ethylpiperazinium cation, 1,4-bis(2-hydroxyethyl)-1,3-diethylpiperazinium cation; and derivatives thereof.

[0048] The structure represented by formula (6) will be described below. In formula (6), R ９ represents a hydrocarbon group that forms a nitrogen-containing aliphatic heterocyclic structure together with the nitrogen atom to which it is bonded, Z １５ ~Z １７ each independently represents a structure represented by formula (X), a hydrogen atom, a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1), or a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1) and a hydroxyl group, Z １５ ~Z １７ At least one of the above is a structure represented by the following formula (X), ５ represents an integer of 0 to 4 (preferably 0 or 1).

[0049] The hydrocarbon group having 1 to 4 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 2 carbon atoms, and even more preferably an alkyl group having 1 carbon atom. The hydrocarbon group having 1 to 4 carbon atoms and having a hydroxyl group is preferably a hydroxyalkyl group having 1 to 4 carbon atoms, more preferably a hydroxyalkyl group having 1 to 2 carbon atoms, and even more preferably a hydroxyalkyl group having 1 carbon atom. The hydrocarbon group may have two or more hydroxyl groups. The structure represented by formula (6) represents a cation of a nitrogen-containing aliphatic heterocyclic structure having at least one structure represented by the following formula (X). The nitrogen-containing aliphatic heterocyclic structure in formula (6) may be a five- to eight-membered ring, and is preferably a five- or six-membered ring. The nitrogen-containing aliphatic heterocyclic structure in formula (6) is preferably, for example, a pyrrolidinium cation. There are no particular limitations on the method for incorporating the structure represented by formula (6) into the structure of a conductive resin. For example, when the conductive resin is a urethane resin, at least one structure represented by formula (6) is incorporated into the structure of the urethane resin by reacting an ionic compound having a structure corresponding to the cation of the nitrogen-containing aliphatic heterocyclic structure represented by formula (6) with an isocyanate group.

[0050] As the nitrogen-containing aliphatic heterocyclic structure in formula (6), the cationic nitrogen-containing aliphatic heterocyclic structure described in the above cation structure column can be used, and among them, a pyrrolidinium cation is preferred. Examples of ionic compounds having a structure corresponding to the cation of the nitrogen-containing aliphatic heterocyclic structure in formula (6) include Z １５ ~Z １７ and n is a hydroxyl group, and n is a divalent hydrocarbon having a straight chain or a branched chain. As an example of this ionic compound, an ionic compound containing a pyrrolidinium cation is given below.

[0051] 1-methyl-1,2-bis(2-hydroxyethyl)pyrrolidinium cation, 1-ethyl-1,2-bis(2-hydroxyethyl)pyrrolidinium cation, 1-butyl-1,2-bis(2-hydroxyethyl)pyrrolidinium cation, 1-methyl-1,2-bis(4-hydroxybutyl)pyrrolidinium cation; and derivatives thereof.

[0052] The structure represented by formula (X) will be described below. In formula (X), R １０ represents a divalent hydrocarbon group having a straight chain or a branched chain, the symbol "*" represents a bond to a nitrogen atom in formulas (1) to (6) or a bond to a carbon atom in a nitrogen-containing heterocyclic structure in formulas (1) to (3) and formulas (5) to (6), and the symbol "**" represents a bond to a carbon atom in a polymer chain constituting a urethane resin having a cationic structure. １０ is preferably a linear or branched alkylene group having 1 to 8 carbon atoms (preferably 1 to 4, more preferably 1 to 2). １０ may have an optional substituent such as a hydroxyl group.

[0053] For example, when the conductive resin is a urethane resin, the structure represented by formula (X) may be a structure formed by reacting an ionic compound having a structure corresponding to the cation of the structure represented by formulas (1) to (6) with an isocyanate compound. The isocyanate compound is preferably a urethane prepolymer obtained by reacting a polyol such as polyether polyol with an isocyanate compound. For example, polymeric MDI can be used as the isocyanate compound.

[0054] Among the structures represented by formulas (1) to (6), when the cation structure includes the structure represented by formula (1) or the structure represented by formula (2), the stability as a cation is high and the dissociation rate from the anion, which is the counter ion, is high. Therefore, when a lithium salt is contained as the supporting electrolyte, the cation structure is likely to interact with the anion of the lithium salt, promoting the dissociation of the lithium salt and improving the ionic conductivity, which is preferable.

[0055] When the conductive resin is a urethane resin, the urethane resin preferably has a first urethane bond and a second urethane bond, and further contains a structure represented by formula (7) and a structure represented by formula (8) between the first urethane bond and the second urethane bond. By containing these structures in the urethane resin, the crystallinity of the polymer main chain is suppressed even when the molecular weight between crosslinking points is large, making it easier to suppress the inhibition of ion migration, particularly at low temperatures. This facilitates improved ionic conductivity and rate characteristics. While there are no particular limitations on the method for producing such a urethane resin, it can be produced, for example, by using a polyethylene glycol-propylene glycol copolymer as a polyol and reacting it with an isocyanate compound. Alternatively, it can be produced by reacting a urethane prepolymer obtained by reacting a polyethylene glycol-propylene glycol copolymer with an isocyanate compound as the isocyanate compound with a polyol.

[0056] It is more preferable that the urethane resin contains a structure represented by the following formula (9). When the urethane resin contains the structure represented by the following formula (9), the crystallinity of the polymer main chain is suppressed, and the inhibition of lithium ion migration, particularly at low temperatures, is more easily suppressed. As a result, the ionic conductivity and rate characteristics are more likely to be improved. In formula (9), m and n are the average number of moles added, each independently a natural number of 1 or more, satisfying n≦m≦9n. m is preferably 1 to 110, more preferably 34 to 102. n is preferably 1 to 55, more preferably 5 to 43. The structure represented by formula (9) can be obtained, for example, by using a polyether polyol obtained by ring-opening polymerization of ethylene oxide and propylene oxide. Note that in formula (9), (-CH ２ -CH ２ -O-) and an ethylene oxide structure represented by (-CH ２ -CH(CH ３ The arrangement of the propylene oxide structure represented by (III)-O-) may be a block copolymer or a random copolymer, preferably a random copolymer.

[0057] The resin structure can be identified by using known analytical techniques, such as pyrolysis GC / MS, TF-IR, and NMR, either alone or in combination. The conductive resin in contact with the inner surface of the active material particles or the conductive resin in contact with the outer surface of the active material particles can be identified by using known techniques capable of mapping the composition, interatomic bonds, crystalline structure, and the like, either in place of or in addition to the aforementioned techniques. Examples of techniques that can be used include viscoelastic mapping using cross-sectional SPM, elemental mapping using TOF-SIMS, carbon-carbon bond mapping using FT-IR and Raman spectroscopy, and structural mapping of soft tissues using a soft X-ray microscope. For the soft X-ray microscope, an inspection device attached to a synchrotron radiation facility such as SPring-8 can be used.

[0058] (Anion Structure) Examples of anions that the conductive resin preferably contains include a fluoroalkylsulfonylimide anion, a fluorosulfonylimide anion, a fluoroalkylsulfonate anion, a fluorosulfonate anion, a fluoroalkylcarboxylate anion, a fluoroalkylmethide anion, a fluoroborate anion, a fluorophosphate anion, a dicyanamide anion, a thiocyanate anion, a bisoxalatoborate anion, a perchlorate anion, and derivatives thereof.

[0059] Specific examples of the fluoroalkylsulfonylimide anion include fluoroalkylsulfonylimide anions having a fluoroalkyl group having from 1 to 6 carbon atoms, such as bis(trifluoromethanesulfonyl)imide anion, bis(pentafluoroethanesulfonyl)imide anion, bis(heptafluoropropanesulfonyl)imide anion, bis(nonafluorobutanesulfonyl)imide anion, bis(dodecafluoropentanesulfonyl)imide anion, and bis(perfluorohexanesulfonyl)imide anion, and cyclic fluoroalkylsulfonylimide anions such as N,N-hexafluoropropane-1,3-disulfonylimide.

[0060] Specific examples of the fluorosulfonylimide anion include bis(fluorosulfonyl)imide anion.Specific examples of the fluoroalkylsulfonate anion include trifluoromethanesulfonate anion, fluoromethanesulfonate anion, perfluoroethanesulfonate anion, perfluoropropanesulfonate anion, perfluorobutanesulfonate anion, perfluoropentanesulfonate anion, perfluorohexanesulfonate anion, and perfluorooctanesulfonate anion.Specific examples of the fluoroalkylcarboxylic acid anion include trifluoroacetic acid anion, perfluoropropionate anion, perfluorobutyrate anion, perfluorovalerate anion, and perfluorocaproate anion. Specific examples of the fluoroalkyl methide anion include fluorinated alkylsulfonyl methide anions such as tris(trifluoromethanesulfonyl)methide anion, tris(perfluoroethanesulfonyl)methide anion, tris(perfluoropropanesulfonyl)methide anion, tris(perfluorobutanesulfonyl)methide anion, tris(perfluoropentanesulfonyl)methide anion, tris(perfluorohexanesulfonyl)methide anion, and tris(perfluorooctanesulfonyl)methide anion.

[0061] Specific examples of fluoroborate anions include tetrafluoroborate anions, and specific examples of fluorophosphate anions include hexafluorophosphate anions.

[0062] Among these anions, at least one selected from the group consisting of a fluoroalkylsulfonylimide anion, a fluorosulfonylimide anion, a fluoroborate anion, a dicyanamide anion, and a thiocyanate anion is particularly preferred because it reduces the decrease in conductivity in a low-temperature environment.

[0063] The conductive resin preferably has higher flexibility than the active material particles. When the conductive resin has higher flexibility than the active material particles, it is more likely to change shape in response to the expansion and contraction of the active material particles during charging and discharging. As a result, it becomes easier to suppress a decrease in ionic conductivity and electronic conductivity. The fact that the conductive resin has higher flexibility than the active material particles can be confirmed by measuring the Young's modulus using a commercially available device such as a nanoindenter.

[0064] The conductive aid is not particularly limited, and examples thereof include graphite such as natural graphite and artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; carbon fluoride powder; conductive fibers such as carbon fibers, carbon nanotubes, and metal fibers; metal powders such as gold, platinum, silver, and aluminum; conductive whiskers such as zinc oxide; conductive metal oxides such as titanium oxide; and organic conductive materials such as phenylene dielectrics.

[0065] The supporting electrolyte is not particularly limited, and for example, a conductive resin can be used as an organic electrolyte, and an inorganic electrolyte such as a lithium salt can be used. In addition, an ion-conductive solid that is usually 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. ４Examples 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.

[0066] The supporting electrolyte is preferably a lithium salt. Examples of the lithium salt include LiClO ４ , LiBF ４ , LiPF ６ , LiAlCl ４ , LiSbF ６ , LiSCN, LiCF ３ SO ３ , LiAsF ６ , lower aliphatic lithium carboxylates, LiCl, LiBr, LiI, lithium chloroborane, lithium tetraphenylborate, LiN(CF ３ SO ３ ) ３ , LiN(C ２ F ５ SO ２ ) ２ Among these, LiN(CF ３ SO ３ ) ３ , LiN(C ２ F ５ SO ２ ) ２ and LiClO ４ It is preferable to use at least one selected from the group consisting of: These lithium salts have high chemical stability with respect to lithium-based active materials, and are less likely to form an insulating coating at the negative electrode interface due to decomposition of the lithium salt. Therefore, the resistance at the negative electrode interface is less likely to fluctuate. The lithium salts can be used alone or in combination of two or more.

[0067] The content of the supporting electrolyte is preferably 0.8 to 40.0 parts by mass, more preferably 5.0 to 40.0 parts by mass, even more preferably 5.0 to 15.0 parts by mass, and particularly preferably 5.0 to 10.0 parts by mass, relative to 100 parts by mass of the conductive resin. When the content of the supporting electrolyte is within this range, the supporting electrolyte is easily miscible with the conductive resin, does not precipitate even at low temperatures, and high ionic conductivity is obtained. The type and content of the indicator electrolyte contained in the conductive resin can be measured by solvent extraction followed by LC-MS or the like.

[0068] 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 In addition, as the solid electrolyte particles of Li—Yb oxide, for example, Li ５．９ Yb ０．８１ La ０．０９ Zr ０．１ (BO ３ ) ３ etc. can be used.

[0069] In an electrode containing an inorganic electrolyte between active material particles, it is preferable that the region containing the conductive resin overlaps the region containing the inorganic electrolyte between the active material particles. This overlap between the region containing the conductive resin and the region containing the inorganic electrolyte between the active material particles is also referred to as the coexistence of the conductive resin and the inorganic electrolyte. It is more preferable that the region containing the conductive resin includes a region containing the inorganic electrolyte. The above-described relationship between the conductive resin and the inorganic electrolyte reduces the interfacial resistance between the inorganic electrolyte particles. Although solid electrolytes (bulk) generally have better ionic conductivity than conductive resins, they are prone to a decrease in conductivity due to interfacial resistance between solid electrolyte particles. The overlap between the conductive resin and the region containing the solid electrolyte particles facilitates the realization of a low-resistance electrode without significantly reducing the high ionic conductivity of the solid electrolyte (bulk). Furthermore, the above-described relationship can be confirmed by the results of elemental mapping in cross-sectional observation, as described below.

[0070] <Method for manufacturing electrode precursor> An example of a method for manufacturing an electrode precursor will be described in detail below with reference to the drawings. Hereinafter, the electrode precursor can be made into a positive electrode precursor by using positive electrode active material particles as the active material particles. Also, the electrode precursor can be made into a negative electrode precursor by using negative electrode active material particles as the active material particles.

[0071] The method for producing an electrode precursor according to the present disclosure preferably includes the following four steps (step 1, step 2, step 3, and step 4). FIG. 1 is a conceptual diagram illustrating the method for producing an electrode precursor. (1) Step 1 (S101 in FIG. 1) is a step of forming a particle layer containing active material particles and electrolyte particles on a resin substrate having an adhesive portion. (2) Step 2 (S102 in FIG. 1) is a step of forming a laminate by stacking a plurality of resin substrates (hereinafter also referred to as substrates) on which the particle layer has been formed. (3) Step 3 (S103 in FIG. 1) is a step of removing the resin substrate from the laminate to form a three-dimensional object containing active material particles and electrolyte particles. (4) Step 4 (S104 in FIG. 1) is a step of post-treating the three-dimensional object.

[0072] (First Step) The first step is a step of forming a particle layer containing active material particles and electrolyte particles on a resin substrate having an adhesive portion. In the first step, particles are arranged on the resin substrate using a particle arrangement device, thereby forming the particle layer. Hereinafter, particle arrangement devices 1 and 2 that can be used will be described in order.

[0073] [Particle Arrangement Apparatus 1] FIG. 2 is a diagram schematically illustrating the configuration of the particle arrangement apparatus 1. Hereinafter, first particles P1 refer to the above-described active material particles, and second particles P2 refer to the above-described electrolyte particles. The particle arrangement apparatus 1 includes a first storage container 21a that stores and supplies a 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 apparatus 1 also includes a first filling device 24a that arranges the first particles P1 in recesses of the concave-convex pattern formed on the first substrate 11a. The particle arrangement apparatus 1 also includes a second storage container 21b that stores and supplies a 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 223a and 223b, which are 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.

[0074] 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.

[0075] In the particle placement device 1, the pattern forming device 23, the first filling device 24a, and the transfer unit 25a can be considered as a first placement unit that places the first particles P1 in a pattern on the resin substrate that is the second substrate 11b. Also, the second filling device 24b can be considered as a second placement unit that places the second particles P2 in areas on the resin substrate that is the second substrate 11b where the first particles P1 are not placed.

[0076] 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.

[0077] 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.

[0078] 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 the drive rollers 221a and 222a.

[0079] The conveying member 224a is preferably made of resin or metal, for example, a polyimide resin belt can be used. The drive rollers 221a, 222a are preferably made of metal, for example, stainless steel metal rollers can be used. The pressure roller 223a is preferably a soft roller having an elastic layer on its surface, for example, a soft roller having a silicone rubber elastic layer on the surface of a stainless steel core can be used.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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).

[0095] 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.

[0096] FIG. 5 is an enlarged view of the surface vicinity of the first substrate 11a in FIGS. 4A to 4C. Although not shown in FIGS. 4A to 4C, 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.

[0097] 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.

[0098] The first particles P1 that come into contact with the recesses are strongly restrained by a 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 particles P1 that are not supported on the support material S1 to exist during the agitation, supply, or transport of the filler 241a.

[0099] 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).

[0100] 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.

[0101] 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.

[0102] 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, depth) 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 depth of the recesses. 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.

[0103] 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.

[0104] 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, the support material S1 may also be restrained and filled in the recess.

[0105] Furthermore, the opening width of the recesses in 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 in the uneven pattern 111a, can be increased. In this way, the first particles P1 that come into multi-point contact with 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 in 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."

[0106] 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.

[0107] The weight 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 commonly used in electrophotographic devices. Then, at least one of the first particles P1 and the support material S1 is replenished as needed by a replenishment means (not shown). This allows for stable filling over a long period of time. The mass percentage 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%.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] The first substrate 11a, in which the recesses of the concave-convex pattern 111a have been filled with the first particles 1 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] The first substrate 11a, which has been filled with the first particles P1 by the first filling device 24a, and the second substrate 11b are transported at approximately the same speed by their respective transport members (224a, 224b) and enter a nip formed by contact between the pressure rollers 223a, 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] Furthermore, the back surface of the second substrate 11b (the surface to which the first particles P1 are not transferred) also preferably has an adhesive portion coated with the same adhesive as the front surface, and the surface is further preferably covered with a protective film or the like. This prevents the substrates from shifting when stacked as described below, and the active material particles and electrolyte particles between the substrates are sandwiched between the upper and lower surfaces (stacking direction) and firmly fixed. This suppresses particle movement during stacking, storage of the laminate, heat treatment, and pressure application, allowing the desired electrode precursor to be formed.

[0130] The adhesive is not particularly limited and may be an acrylic adhesive, a rubber adhesive, a silicone adhesive, or a thermoplastic resin or a photocurable resin whose adhesive strength changes in response to external disturbances such as heat or light. The particle placement device 1 may also have a coating means such as a dispenser or inkjet head for applying the adhesive to the surface of the second substrate 11b during transport. The type and amount of adhesive applied are adjusted as appropriate 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 other factors. However, it is preferable that the adhesive strength be greater than that of the concave-convex pattern 111a. Comparison of adhesive strength can be measured using a common method using a nanoindenter.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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 appropriately selected depending on the particle size and material of the second particles P2 and the opening width of the voids described above. The mass percentage 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%.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] Although the first particles P1 and the second particles P2 are placed by one filling device 24a and one filling device 24b, multiple filling devices may be used. This can improve the compactness. Furthermore, the particles are not limited to the first particles P1 and the second particles P2. By adding a filling device, third particles other than the first particles and the second particles can also be placed.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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. As a result, the first particles P1 are fixed by the material on the substrate 11, and the particles P1 are fixed in a pattern corresponding to the pattern L1.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] In the particle arrangement devices 1 and 2, the coverage of the resin substrate by the first particles P1 and the second particles P2 is preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more. The coverage of the resin substrate by the first particles P1 and the second particles P2 can be measured by photographing the region where the particle layer is formed using an optical microscope from a direction perpendicular to the substrate and calculating the area ratio of the first particles P1 and the second particles P2 in that region using image processing software.

[0153] By using the particle placement device 1 or particle placement device 2 described above, the 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 the second particles P2 are placed.

[0154] (Second Step) The second step is a step of forming a laminate by stacking a plurality of resin substrates (hereinafter also referred to as substrates) on which particle layers are formed. The number of layers of the laminate is not particularly limited and is determined according to the desired electrode capacity. In addition, the laminate is preferably formed on a current collector such as a positive electrode current collector as a substrate. That is, the laminate preferably includes a substrate. As the current collector, known current collectors such as Al foil, SUS foil, platinum foil, and gold foil can be used. An electrolyte may also be used as the substrate.

[0155] In this case, the electrolyte may be a separately prepared solid electrolyte sheet or an electrolyte substrate consisting of only electrolyte particles on a similar substrate. A solid electrolyte may also be used as the electrolyte. When the electrode is a positive electrode, the solid electrolyte sheet or electrolyte substrate may have a negative electrode or a negative electrode substrate formed on the opposite side of the positive electrode substrate.

[0156] 11 is a diagram showing a schematic configuration of the laminate forming apparatus U3. The laminate forming apparatus U3 includes a conveying device 31 that conveys the substrate 11 on which the 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).

[0157] 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.

[0158] 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 second 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.

[0159] 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 second 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.

[0160] (Third Step) The third step is a step of removing the resin substrate from the laminate to form a three-dimensional object containing active material particles and electrolyte particles. Preferably, the third step is a step of sintering the laminate to remove the resin substrate from the laminate. This allows the active material particles to have inner and outer surfaces. In other words, the third step can be said to be a step of forming inner surfaces on the active material particles, or a step of forming outer surfaces on the active material particles. Figure 12 is a diagram schematically showing the configuration of the sintering processing device U4. The sintering processing device U4 has a conveying device 41 that conveys the laminate 15 and a heating furnace 42 that heats the laminate 15.

[0161] 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.

[0162] 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 (423a and 423b). 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.

[0163] 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.

[0164] When sintering the laminate, it is preferable to heat it 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, particularly preferably 450°C or higher and 800°C or lower, and even more preferably 450°C or higher and 650°C or lower. It is preferable to maintain the sintering temperature for 30 minutes or longer, more preferably 1 hour or longer. The upper limit is not particularly limited, but may be, for example, 3 hours or shorter, or 2 hours or shorter. For example, it is preferable to maintain the sintering temperature for 30 minutes to 3 hours, or 1 hour to 2 hours. 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 substrate 11 can be removed from the laminate.

[0165] 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 weight is reduced to 70% of the initial weight. Specifically, for example, 385°C or higher is preferable.

[0166] Similarly, when thermogravimetric analysis is performed, it is more preferable to heat the substrate 11 at a temperature equal to or higher than the temperature at which the substrate 11 loses 50% of its initial weight, and even more preferable to heat the substrate 11 at a temperature equal to or higher than the temperature at which the substrate 11 loses 20% of its initial weight. Specifically, for example, a temperature of 400°C or higher is preferable, and 450°C or higher is more preferable. This can shorten the time required to remove the substrate 11 and increase the removal rate of the substrate 11.

[0167] In this way, when the sintering treatment device 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 device removes the substrate 11 by heating, it is preferable that the active material particles be made of a material having a softening point temperature higher than the thermal decomposition temperature of the substrate 11.

[0168] The sintering treatment device preferably removes 90% by weight or more of the resin substrate in the laminate 15 by heating, more preferably removes 95% by weight or more, and even more preferably removes 97% by weight 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.

[0169] 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, of 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 exists, when the resin substrate surface is (x, y) and the lamination direction of the resin substrate is (z).

[0170] 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 below.

[0171] 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.

[0172] The cross section of the electrode is observed by processing the cross section with a broad ion beam (BIB) of Ar and then obtaining a two-dimensional image of the cross section using a scanning electron microscope. Hereinafter, the above-mentioned method of observing two-dimensional images will be referred to as BIB-SEM. The details of the measurement method will be described later.

[0173] <BIB-SEM Imaging Method> Cross-sectional images of the electrode are taken using a BIB-SEM. The BIB-SEM imaging conditions are described below. If the electrode is included in a battery, the battery is disassembled and a sample containing the electrode is removed. For example, in the case of a laminated battery, the laminate is opened and the laminate containing the electrode is removed. To reduce the load of the cross-sectional processing described below, the other current collector and electrode not required for imaging are separated from the laminate, and the sample containing the electrode is removed. The electrode can be identified as the region between the electrolyte layer and the current collector. The sample is cut using a wire saw (DWS3400 / wire diameter 170 μm, diamond diameter 30 μm) to obtain a cut surface along the stacking direction. The cut surface is cross-sectionally processed using a broad ion beam of Ar (JEOL SM-09010 Cross Section Polisher). The cross-sectional processing conditions are a voltage of 6 kV and a current of 150 to 200 mA. A cross section of the electrode sample in the lamination direction is obtained as a BIB-SEM image, and the cross section is observed. Instead of a broad ion beam (BIB), a fine ion beam (FIB) can also be used, in which the ion particle intensity and beam diameter in the beam are changed.

[0174] The cross section is photographed using an electron microscope (ULTRA55) under the following conditions: Detector: ESB (backscattered electron image) Observation conditions: Acceleration voltage 3 kV Magnification: 1000x Filter: A bias of 1500 V is applied to the ESB filter

[0175] Next, elemental and compositional analysis of each particle of the electrode and the conductive resin was performed using SEM-EDX (Bruker XFlash Detector 630M), and the active material particles, electrolyte particles, and conductive resin were identified. The active material particles, electrolyte particles, and conductive resin were identified using the method described above. The electrode was analyzed using X-ray diffraction (XRD) or the like to identify the materials constituting the electrode. Thereafter, the specific elements contained in each of the active material particles, electrolyte particles, and conductive resin were detected and identified using SEM-EDX using the method described above. In addition to the X-ray diffraction described above, the materials constituting the electrode can also be identified using electron energy loss spectroscopy (EELS) in a TEM. Furthermore, they can also be identified using Raman spectroscopy or TOF-SIMS, and the materials constituting the electrode may be identified by combining the above-described analytical methods.

[0176] The thickness of the resin substrate is preferably 1 μm or more and 1 mm or less, and the thickness of the particle layer is preferably 0.1 μm or more and 100 μm or less.

[0177] By using a substrate formed of an organic material such as a resin as the substrate, it is possible to easily remove the substrate by heating. Materials that can be used to form the substrate include polyesters such as polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), and polyamides such as nylon. Of these, PET is preferred from the viewpoints of its decomposition temperature and the low toxicity of gases generated during thermal decomposition.

[0178] 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 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.

[0179] 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.

[0180] FIG. 13A is a BIB-SEM image of the cross section of the laminate after the second step. It corresponds to the cross section of the laminate 15 in which six lamination units, each including a particle layer 12 and a second substrate 11b, are stacked on a resin substrate 14, with the particle layers 12 and the second substrate 11b alternately stacked. FIG. 13B is a BIB-SEM image of the three-dimensional object 16 after the third step. The resin substrate has been removed from the laminate 15, resulting in a three-dimensional object 16 consisting of six particle layers. FIG. 13C 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 after the second step.

[0181] 14A is a BIB-SEM image of a three-dimensional object 16 according to one embodiment (Example 1) of the present disclosure. FIG. 14B is an enlarged image of FIG. 14A. The first particles P1 are positive electrode active material particles of LiCoO ２ (hereinafter referred to as LCO), and the second particle P2 is the electrolyte particle Li ３ BO ３ (hereinafter referred to as LBO) is used to form a three-dimensional object 16 by the manufacturing method of the present disclosure. In this embodiment, as shown in FIGS. 14A and 14B , the LCO particle (first particle P1) has a core portion P1a, a shell portion P1b, and radially protruding protrusions P1c on the surface of the shell portion. A gap portion P1d exists between the core portion and the shell portion. In FIG. 14B , P1d is an internal hole in the active material particle that communicates with the outer surface of the active material particle, and can also be referred to as a communicating hole 19-1. The LCO particle also has an inner surface 19 as shown by the solid line.

[0182] Using Figures 15 to 18-1 and Figures 18-2A to 18-2D, we will explain the presumed mechanism by which the three-dimensional object 16 has the above-mentioned configuration in this embodiment. Figure 15A shows an example of a temperature profile in each step (S101 to S104) of the electrode precursor manufacturing method of the present disclosure, and a profile showing the redox behavior depending on the atmosphere. Figure 15B is a schematic diagram showing the change in LCO particles in the profile shown in Figure 15A. In the first step (S101) and the second step (S102), the LCO particles on the resin substrate remain unchanged because they are heated at room temperature and in an air atmosphere (or an inert atmosphere). On the other hand, in the third step (S103), the resin substrate is heated by a sintering treatment device (in an air atmosphere). Here, when the temperature exceeds the melting point of the resin substrate and the substrate is sufficiently heated, the weight of the substrate begins to decrease.

[0183] Figure 16 shows the results of thermogravimetry (TG) of the resin substrate. Weight loss begins near 300°C, above the melting point of the resin substrate (approximately 260°C). Figure 17 shows the results of thermogravimetry and mass spectrometry (TG-MS). Figure 17A shows the measurement results for a mixed sample of LCO particles and resin substrate. Figure 17B shows the measurement results for a sample consisting of only the resin substrate. Around 300°C, where weight loss of the resin substrate begins, an increase in molecules with a molecular weight of 28, believed to be carbon monoxide (CO), a reducing gas, is observed. In Figure 17B, CO tends to increase up to around 500°C (solid line in Figure 17B), whereas in Figure 17A, CO tends to decrease just before 400°C (solid line in Figure 17A). Additionally, near 500°C in Figure 17A, a decrease in molecules with a molecular weight of 32, believed to be oxygen, was observed (dashed line in Figure 17A), and an increase in molecules with a molecular weight of 44, believed to be carbon dioxide, was observed (dotted line in Figure 17A). From the results of TG and TG-MS, the following is inferred.

[0184] As the temperature rises, the weight of the resin substrate begins to decrease (around 300°C), generating CO, a reducing gas, and increasing the reducibility. Some of the generated CO contributes to the reduction of the LCO particles. Therefore, it is thought that the LCO particles are reduced and decomposed, changing into particles P1r that have some voids inside the LCO particles (Figure 15B). On the other hand, the amount of CO generated decreases as the substrate decreases, so reductive decomposition gradually becomes more difficult. As the weight of the substrate decreases, the influence of CO decreases, and oxidation becomes dominant over reduction for the LCO particles. The reduced particles P1r are oxidized again to trivalent Co, LiCoO ２ (around 500°C). At this time, it is believed that the LCO particles change into LCO particles having a core portion P1a, a shell portion P1b, and radially protruding protrusions P1c on the surface of the shell portion, while retaining the voids P1d generated during the reductive decomposition inside the LCO particles. Figures 18-2A to 18-2D show the results of STEM-EELS (Figures 18-2A to 18-2D) at the respective locations shown in Figures 18-2A to 18-2D of the LCO particles (Figure 18-1) after the third step. It can be confirmed that the core portion P1a (Area 4 in Figure 18-2D), shell portion P1b (Area 2 in Figure 18-2B), and protrusions P1c (Area 1 in Figure 18-2A) of the LCO particles contain Co and are oxides with approximately the same composition.

[0185] (Step 4) Step 4 is a step of post-treating the three-dimensional object obtained in Step 3. By performing the post-treatment, it becomes easier to fill the electrode precursor with the filler material in the filling step (Step 2-1) described below. In addition to the pressurizing step described below, post-treatments include physical and chemical treatments for improving wettability and filling ability, and known treatment methods can be used. Specifically, physical treatments include physical treatment of the three-dimensional object by laser edging, etc. Further examples include surface modification by UV irradiation or corona discharge, and chemical treatments such as gas adsorption. Below, the pressurizing step will be described as an example.

[0186] For example, the fourth step is a step of pressurizing the three-dimensional object 16 obtained in the third step from which the resin substrate has been removed (FIG. 12). The three-dimensional object 16 may be pressurized using a pressurizing means 422 during cooling or heat dissipation after heating. Alternatively, after removing the resin substrate using a sintering treatment device, the object may be pressurized using a separate pressurizing device. While the pressurizing method is not particularly limited, it is preferable to use, for example, vacuum degassing, isostatic pressing, a general hydraulic press, or a roller press. Among these, a combination of vacuum degassing and isostatic pressing is preferred. Furthermore, it is preferable to perform the fourth step by laminating the three-dimensional object with a release material such as nichrome foil, and even more preferable to package the object in a laminate film. The pressure during pressurization is preferably 5 to 500 MPa. Pressurization reduces the size of the pores (voids) within the three-dimensional object from which the resin substrate has been removed. Generally, as is known from capillary action, liquids become more easily permeable as pore size decreases. Therefore, by performing post-treatment under pressure, the packing property of the filler material during the packing process of the filler material described below is further improved. Furthermore, by performing post-treatment under pressure, the particles constituting the three-dimensional object can be more easily brought into contact with each other. As a result, the ionic conductivity and electronic conductivity can be increased, and the strength of the three-dimensional object can be increased. After the fourth step, heat treatment may be performed again to increase the density and strength of the three-dimensional object. In this case, the sintering treatment device of the third step may be used, or sintering may be performed separately using an electric furnace, a tubular furnace, a hot press, a hot isostatic pressing device (HIP), or the like.

[0187] The electrode precursor obtained through steps 1 to 4 contains active material particles and electrolyte particles and has voids. The voids refer to, for example, the gaps between the active material particles and the electrolyte particles. The presence of voids allows for filling with a filler material, as described below. The proportion of voids in the electrode precursor may be 1 to 30% by volume, or may be 5 to 20% by volume. If the voids are small, it is difficult for the filler material to be filled into the electrode precursor in the filling material filling step described below, making it difficult for the filler material to exert its effects. On the other hand, if the voids are large, contact between the active material particles and the electrolyte particles may be insufficient, resulting in reduced ionic and electronic conductivity within the electrode. The void proportion can be determined using a so-called 3D-SEM, in which continuous cross-sectional images are obtained by repeatedly performing cross-sectional processing (FIB) and SEM observation, and then reconstructed using analysis software to obtain a three-dimensional image. For a 50 μm x 50 μm region of the electrode part, cross-section processing and SEM observation are repeated every 0.1 μm in the stacking direction to obtain a 50 μm x 50 μm x 10 μm three-dimensional image, and the void ratio is calculated. Alternatively, the void ratio may be determined from a BIB-SEM image of a two-dimensional positive electrode cross section. In this case, an SEM image of a 500 μm x 10 μm region including the center of the positive electrode cross section may be obtained to calculate the void ratio. The ratio of voids (pixels) to the entire image (pixels) can be calculated using commercially available image analysis software (Photoshop (registered trademark)).

[0188] <Electrode Manufacturing Method> An example of an electrode manufacturing method will be described in detail below with reference to the drawings. Hereinafter, an electrode can be made into a positive electrode by using a positive electrode precursor as an electrode precursor. Also, an electrode can be made into a negative electrode by using a negative electrode precursor as an electrode precursor.

[0189] The method for producing an electrode according to the present disclosure comprises the following four steps (step 1-1, step 2-1, step 3-1, and step 4-1). It may also comprise step 5-1. Here, the order of steps 1-1 and 2-1 is not particularly limited, and step 2-1 may be performed after step 1-1, or step 1-1 may be performed after step 2-1. FIG. 19 is a conceptual diagram showing the method for producing an electrode. (1) Step 1-1 (not shown) of preparing an electrode precursor containing active material particles and having voids between the active material particles; (2) Step 2-1 (S201 in FIG. 19) of preparing a filler material to be filled into the electrode precursor; (3) Step 3-1 (S202 in FIG. 19) of filling the electrode precursor from the outside to the inside with the filler material; (4) Step 4-1 (S203 in FIG. 19) of retaining the filler material filled inside the electrode precursor inside the electrode precursor; and (5) Step 5-1 (S204 in FIG. 19) of post-treating the electrode precursor obtained by Step 4-1.

[0190] (Step 1-1) Step 1-1 is a step of preparing an electrode precursor containing active material particles and having voids between the active material particles. Step 1-1 is not particularly limited as long as it is possible to prepare an electrode precursor, but for example, the electrode precursor can be prepared using the above-mentioned electrode precursor manufacturing method. That is, step 1-1 preferably includes a first step of forming a particle layer containing active material particles and electrolyte particles on a resin substrate having an adhesive portion, a second step of forming a laminate in which a plurality of resin substrates on which the particle layer is formed are stacked, a third step of removing the resin substrate from the laminate, and a fourth step of post-treating the three-dimensional object containing active material particles and electrolyte particles.

[0191] (Step 2-1) Step 2-1 is a step of preparing a filler material to be filled into the electrode precursor. Examples of step 2-1 include blending and preparing the following raw materials. As described above, the filler material needs to be liquid in order to fill the voids in the electrode precursor. For example, the filler material may be a solution obtained by dissolving at least one selected from the group consisting of a conductive resin and a conductive resin precursor in a solvent, or a dispersion obtained by dispersing at least one selected from the group consisting of a conductive resin and a conductive resin precursor in a dispersion medium. Examples of conductive resin precursors include monomers, oligomers, and polymers such as thermosetting resins and photocurable resins. In other words, the conductive resin is preferably a cured product of a conductive resin precursor. Specific examples of conductive resin precursors include ionic compounds having structures corresponding to the structures represented by the above formulas (1) to (6), the above polyols, and the above isocyanate compounds.

[0192] Examples of the filler material include a mixture of the following raw materials: At least one selected from the group consisting of conductive resins and precursors of conductive resins; a supporting electrolyte such as a lithium salt, if necessary; a solvent or dispersion medium; and a conductive assistant, if necessary.

[0193] The solvent or dispersion medium is not particularly limited, and for example, an organic solvent can be used. Examples of the organic solvent include alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone, acetone, and acetylacetone, and hydrocarbon solvents such as hexane and cyclohexane. Among these, methyl ethyl ketone is preferred.

[0194] The filler material may contain a supporting electrolyte. By containing the supporting electrolyte in the filler material, the conductive resin in the electrode can contain the supporting electrolyte. In addition, the above-mentioned supporting electrolyte and conductive assistant can be used.

[0195] (Step 3-1) Step 3-1 is a step of filling the electrode precursor from the outside to the inside with the filler material prepared in Step 2-1. The filling means can be a known liquid filling means. The filling means preferably includes, for example, a coating step of applying the filler material to the electrode precursor and a penetration step of penetrating the applied filler material into the inside of the electrode precursor. It is more preferable to include a penetration step of penetrating the filler material into the inside of the electrode precursor so as to contact the inner surfaces of the active material particles, or a penetration step of penetrating the filler material into the inside of the electrode precursor so as to contact the outer surfaces of the active material particles. Examples of devices used in the coating step include an inkjet device, a dispenser device, a dip coater, a spin coater, a spray coater, and a roll coater. Of these, a dispenser device is preferably used. Examples of devices used in the penetration step include a vacuum dryer and a vacuum packaging machine. Pressure may be applied using a weight or the like to support penetration.

[0196] FIG. 20A is a schematic diagram showing the filling process using a dispenser device 511. The filling material 50 is contained in a syringe in the dispenser device 511 and applied to the electrode precursor 18 through a nozzle at the tip of the syringe. Meanwhile, the electrode precursor 18 formed on the substrate 14 (electrode current collector or solid electrolyte sheet) is fixed to a support table 512. Here, the filling material may be applied to a surface 18-1 (hereinafter also referred to as a particle arrangement surface) opposite to a contact surface 18-2 (hereinafter also referred to as a substrate support surface) of the electrode precursor 18 that contacts the substrate 14, or to an end 17 of the electrode precursor 18. However, it is preferable that the filling material be applied to the end 17. The reason for this will be described later. The end refers to the xz and yz surfaces when the substrate surface of the electrode precursor is the xy plane and the stacking direction is the z direction ( FIG. 13B ). In the third step, the electrode precursor 18 is formed into a three-dimensional object by removing the resin substrate from the laminate. Therefore, the electrode precursor 18 has pores that communicate with the particle-arranged surface 18-1. Also, pores that communicate with the end 17 are provided. This facilitates uniform penetration of the filler material 50 throughout the electrode precursor 18. As a result, the conductive resin is more likely to be positioned so as to contact the inner surfaces of the active material particles. Furthermore, the conductive resin is more likely to be positioned so as to contact the outer surfaces of the active material particles and connect the active material particles. Furthermore, the interlayer spaces between the layers of the laminate structure of the electrode precursor are exposed at the end. Therefore, when the filler material is applied to the end, the filler material is more likely to be filled into the interior. On the other hand, when the filler material 50 is applied from the particle-arranged surface 18-1 of the electrode precursor 18, i.e., from the xy plane, it is preferable to apply the filler material 50 in small amounts to multiple locations on the xy plane to ensure uniform penetration.

[0197] 20B is a schematic diagram showing the filling process using a dip coating device 513. The filling material 50 is contained in a dipping container 514. As the dip coating device 513 moves in the direction of the arrow, the filling material 50 is applied to the end of the electrode precursor 18.

[0198] 20C is a schematic diagram showing the filling process using a spin coater 515. The filler material 50 is contained in a syringe in a dispenser device 511 and is applied onto the resin substrate 14 through a nozzle at the tip of the syringe. Meanwhile, the electrode precursor 18 formed on the resin substrate 14 (electrode current collector or solid electrolyte sheet) is fixed to a support table of the spin coater 515. The filler material 50 applied onto the resin substrate 14 is applied to the end of the electrode precursor 18 by centrifugal force from the spin coater 515.

[0199] (Step 4-1) Step 4-1 is a step of retaining the filler material filled into the electrode precursor in Step 3-1 within the electrode precursor. The means for retaining the filler material are not particularly limited and are appropriately selected depending on the filler material. Examples include a step of thickening the filler material and a step of curing the filler material. Specifically, when a thermosetting polymer electrolyte is used as the filler material, known means such as a vacuum oven can be used. When a UV-curable polymer electrolyte is used as the filler material, known means such as a UV irradiation device can be used. When a UV irradiation device is used, depending on the thickness of the electrode, the filler material may not be easily cured by UV irradiation. In that case, the thickness of the electrode precursor is set to a thickness that allows the filled filler material to be easily cured, and multiple electrode precursors are molded on a substrate with high releasability. After the filler material is cured in each electrode precursor, the electrodes can be obtained by transfer lamination. Furthermore, the filling in Step 3-1 may be performed all at once or in small amounts in multiple batches. Specifically, when filling is performed in small amounts in multiple steps, an electrode may be obtained as follows. That is, after a small amount of filling is performed once in step 3-1, the filling material is retained inside the electrode precursor in step 4-1. Thereafter, filling is performed again in step 3-1, and the filling material is retained inside the electrode precursor in step 4-1. In this way, step 3-1 and step 4-1 may be repeatedly performed to obtain an electrode precursor. The electrode precursor obtained in step 4-1 can be used as an electrode. Furthermore, it is preferable to subject the electrode precursor obtained in step 4-1 to step 5-1 to form an electrode.

[0200] (Step 5-1) Step 5-1 is a step of post-treating the electrode precursor obtained in Step 4-1 to obtain an electrode. Examples of post-treatment include a pressurizing step of pressurizing the electrode precursor obtained in Step 4-1, a buffer layer formation step of forming an interfacial buffer layer with the electrolyte on the surface of the electrode, and a packaging step of vacuum-packaging using a protective film or an AL laminate film to prevent peeling, cracking, or exposure to the atmosphere during transportation or storage. Known means for pressurizing in the pressurizing step can be used, specifically vacuum degassing, isostatic pressing, or a general hydraulic press or roller press. Of these, a combination of vacuum degassing and isostatic pressing is preferred. Known coating means can be used in the buffer layer formation step, specifically vacuum deposition, ion plating, sputtering, chemical vapor deposition (CVD), and the coating means of Step 3-1. A separately prepared buffer layer sheet (such as a polymer electrolyte sheet) may be laminated without using the above-mentioned means. Furthermore, the amount of filler material to be filled in step 3-1 may be controlled in advance to provide a buffer layer on the electrode so that the filler material to be filled in step 3-1 also serves as a buffer layer.

[0201] <Secondary Battery Manufacturing Method> A secondary battery can be manufactured using the above-described electrode manufacturing method. The method for manufacturing a secondary battery is not particularly limited, and the following specific examples can be mentioned. A case where the above-described electrode manufacturing method is used as a manufacturing method for a positive electrode or a negative electrode will be described. A positive electrode or a negative electrode, or both a positive electrode and a negative electrode, can be manufactured by the above-described electrode manufacturing method using a current collector or an electrolyte formed by a separate means as a base.

[0202] 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.

[0203] Here, the alternative electrolyte forming method is a known method, such as pelletizing electrolyte particles using a uniaxial press or the like and sintering them in an electric furnace or the like. A secondary battery can be manufactured by stacking the manufactured components in the following order: positive electrode current collector, positive electrode, electrolyte, negative electrode, and negative electrode current collector. Examples of secondary batteries include laminated batteries packaged in a laminate film and coin-type batteries packaged in a coin case. The particles constituting the positive electrode, electrolyte, and negative electrode may have different suitable temperatures or atmospheres for 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 the current collector and electrolyte using a vacuum process such as sputtering. Due to its strong reducing power, lithium metal is prone to decomposition depending on the solid electrolyte. In this case, a buffer layer may be provided between the electrode and the electrolyte. A polymer electrolyte or the like is preferably used as the buffer layer.

[0204] A specific example of the secondary battery manufacturing method described above uses the electrode manufacturing method described above to form a positive electrode or negative electrode laminate using a current collector or electrolyte as a base to produce an electrode. Alternatively, a secondary battery can be manufactured as a three-dimensional object including an electrode by forming a laminate containing two or more components selected from the group consisting of a positive electrode current collector, a positive electrode, an electrolyte, a negative electrode, and a negative electrode current collector. For example, each substrate is prepared using the particle arrangement device 1. 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 (e.g., positive electrode active material particles and electrolyte particles in the case of a positive electrode substrate), or may contain only a single type of particle. When only a single type of particle is contained, a single type of dense particle layer can be formed on the substrate by using the same type of filler in the filling devices 24a and 24b. The electrolyte substrate is formed from a particle layer containing electrolyte particles. The negative electrode substrate is formed from a particle layer containing negative electrode active material particles. The current collector substrate is formed of a particle layer containing conductive particles. These substrates are stacked in the following order using a laminate molding device: a positive electrode current collector substrate, a positive electrode substrate, an electrolyte substrate, a negative electrode substrate, and a negative electrode current collector substrate. A laminate is then formed using a sintering device to form a three-dimensional object containing electrodes, thereby obtaining a secondary battery precursor containing an electrode precursor. A secondary battery can be manufactured by filling and retaining a filler material in the electrode precursor (steps 2-1 to 4-1). Furthermore, bipolar secondary batteries can also be manufactured in a similar manner, in which a positive electrode and a negative electrode are stacked on both sides of the current collector substrate. In this case, the filler material is filled and retained in at least the electrodes, but it may also be filled and retained in the electrolyte or current collector other than the electrodes.

[0205] The electrode composite includes the electrode of the present disclosure and an electrolyte layer that transfers active material between the electrode and the electrolyte layer. By providing an electrode serving as a positive electrode or a negative electrode in the electrode composite, it is possible to provide a secondary battery that can mitigate expansion and contraction of the active material particles and suppress a decrease in battery output.

[0206] <Secondary Battery> The secondary battery includes a positive electrode according to the present disclosure and an electrolyte layer that transfers active material between the positive electrode and the electrolyte layer. The secondary battery also includes a negative electrode that transfers active material between the negative electrode and the electrolyte layer. Such a secondary battery can mitigate expansion and contraction of active material particles and suppress a decrease in battery output. Furthermore, by using a solid electrolyte such as an ion-conductive solid as the electrolyte layer, the secondary battery can be an all-solid-state battery. The method for manufacturing the secondary battery is not particularly limited, but the above-mentioned manufacturing method can be used.

[0207] The present disclosure will be described in more detail below using examples, but the present disclosure is not limited to these examples. In the following examples, unless otherwise specified, the number of parts is based on parts by mass.

[0208] Example 1 [Example of manufacturing a positive electrode] <Example of manufacturing a positive electrode precursor> A positive electrode precursor according to Example 1 was formed by the above-described method for manufacturing an electrode precursor. First, using a particle arrangement device 1 shown in FIG. 2, a particle layer consisting of positive electrode active material particles (first particles P1) and electrolyte particles (second particles P2) was formed on a resin substrate having an adhesive portion to form a resin substrate (first step). The first particles P1 were LiCoO ２ (hereinafter referred to as LCO), and the second particle P2 is Li ３ BO ３ (hereinafter referred to as LBO). The LCO used was manufactured by Nippon Chemical Industry Co., Ltd. (Cellseed C-5H), and the LBO used was manufactured by Toshima Manufacturing Co., Ltd. The first substrate 11a was a PDMS (ultraviolet-curable liquid silicone rubber) sheet having an uneven surface. The second substrate 11b was a resin sheet made of polyester (PET) with adhesive portions coated with acrylic adhesive material on both sides. The thickness of the second substrate 11b (PET) used was 3 μm. The thickness of the adhesive portions was 1 μm. LCO particles were arranged in a honeycomb pattern on the resin sheet, and LBO particles were arranged in areas where no LCO particles were arranged ( FIG. 9B ).

[0209] The second step was carried out using the resin substrate on which the particle layer was formed obtained in the first step. That is, using the laminate molding apparatus U3 shown in FIG. 11, the resin substrate on which the particle layer was formed was laminated (three layers) on the current collector AC-1 (Al foil) to form a laminate. Then, using the sintering treatment apparatus U4 shown in FIG. 12, a three-dimensional object was formed by removing the resin substrate from the laminate by heating (third step). The sintering atmosphere was air, the sintering temperature was 510 ° C, and the sintering time was 1 hour. The three-dimensional object was laminated with a release material (nichrome foil), packaged in a laminate film (Co-pack), and vacuum-packed using a vacuum packaging machine. The vacuum-packed laminate film was pressurized (196 MPa) for 1 minute using an isostatic pressure pressurizer to obtain a positive electrode precursor (fourth step).

[0210] <Preparation Example of Filling Material (Step 2-1)> (Production Example of Ionic Compound I-01) A stirrer and 60 ml of tetrahydrofuran (THF, manufactured by Kanto Chemical Co., Ltd.) were placed in a recovery flask equipped with a Dimroth condenser. 24.0 g (0.60 mol) of sodium hydride (60% by mass, dispersed in liquid paraffin, manufactured by Tokyo Chemical Industry Co., Ltd.) was dispersed therein, and the recovery flask was cooled in an ice bath. A solution of 10.2 g (0.15 mol) of imidazole (manufactured by Tokyo Chemical Industry Co., Ltd.) dissolved in 60 ml of THF was slowly added dropwise, after which the ice bath was removed and the mixture was stirred at room temperature for 2 hours. 47.6 g (0.38 mol) of 2-bromoethanol (manufactured by Tokyo Chemical Industry Co., Ltd.) was added at room temperature, and the mixture was heated to reflux at 70°C for 7 hours. After the reaction, the reaction solution was filtered, the insoluble matter was washed away with THF, and the solvent from the resulting filtrate was evaporated under reduced pressure. The obtained product was dissolved in 200 ml of dichloromethane, and an aqueous solution containing 43.6 g (0.15 mol) of bis(trifluoromethanesulfonyl)imide lithium (manufactured by Tokyo Chemical Industry Co., Ltd.) dissolved therein as an anion source was added, followed by stirring at room temperature for 10 hours. The obtained solution was separated to obtain an organic layer. This organic layer was washed three times with pure water. Next, dichloromethane was distilled off under reduced pressure to obtain ionic compound I-01. Ionic compound I-01 is a compound represented by the following formula:

[0211] (Example of production of a conductive resin precursor) In a nitrogen atmosphere, 120.5 parts by mass of polyether polyol (trade name: Adeka Polyol PR-5007, manufactured by ADEKA Corporation) was gradually added dropwise to 19.6 parts by mass of polymeric MDI (trade name: Millionate MR-200, manufactured by Tosoh Corporation) as an isocyanate in a reaction vessel while maintaining the temperature inside the reaction vessel at 65°C. After completion of the addition, the mixture was allowed to react at a temperature of 65°C for 3.5 hours. The resulting reaction mixture was cooled to room temperature, and 49.8 parts by mass of methyl ethyl ketone was added to obtain a solution of an isocyanate-terminated prepolymer having an isocyanate group content of 2.5% by mass.

[0212] The following materials were mixed with 100 parts by mass of the obtained solution of isocyanate group-terminated prepolymer by stirring to obtain a filling material: Adeka Polyol PR-5007 113 parts by mass Ionic compound I-1 3.7 parts by mass Supporting electrolyte (lithium bis(trifluoromethanesulfonyl)imide (manufactured by Tokyo Chemical Industry Co., Ltd.)) 18.6 parts by mass Methyl ethyl ketone 175 parts by mass

[0213] Next, the positive electrode precursor obtained in step 4 was filled with the prepared filler material from a portion of the end face located on the periphery of the positive electrode precursor using the coating device shown in FIG. 20A (step 3-1). The positive electrode precursor filled with the filler material was heated in a vacuum oven (140 °C) for 1 hour to harden the filler material into a conductive resin, and positive electrode A-1 was formed (step 4-1). Samples with varying filling amounts of filler material were prepared, and the level of conductive resin penetration into the electrode was determined using the BIB-SEM described above.

[0214] A secondary battery was fabricated using the molded positive electrode A-1. The fabrication method will be described. The electrolyte layer SE-1 and the negative electrode C-1 other than the positive electrode A-1 were prepared by the following method. The electrolyte layer SE-1 was made of Li １．５ Al ０．５ Ge １．５ P ３ O １２(hereinafter referred to as LAGP) powder (manufactured by Toshima Manufacturing Co., Ltd.) was pelletized using a uniaxial press and sintered in an electric furnace (850 ° C / 12 h) to form an electrolyte sheet (thickness 260 μm). Anode C-1 was made of indium foil (thickness 50 μm, manufactured by Nilaco). A cathode current collector AC-1 (Al foil thickness 20 μm), cathode A-1, electrolyte layer SE-1, anode C-1, and anode current collector CC-1 (Cu foil thickness 20 μm) were stacked in this order, and a tab lead for the extraction electrode previously welded to the current collector was packaged in an aluminum laminate film so as to be positioned outside the laminate. Then, the laminate was formed into a laminate cell type using a vacuum packaging machine and pressurized (196 MPa) for 1 minute using an isostatic pressure press to produce secondary battery SB-1.

[0215] 22A to 22D are electron microscope images of the cross section of positive electrode A-1 taken using the method described below. FIG. 22A is an electron microscope image. FIG. 22B identifies LCO particles (P1t, P1u, P1v, P1w, P1x, P1y, and P1z) based on an EDX image (element Co), with particle boundaries indicated by dashed lines. The LCO particles have a core portion P1a, a shell portion P1b, and radially extending protrusions P1c on the surface of the shell portion. Furthermore, a gap P1d exists between the core portion and the shell portion (FIG. 14). In FIG. 22B, the boundaries of the gaps P1d within particles P1t and P1u are indicated by solid lines. In other words, the solid lines can also be said to represent the inner surfaces of the active material particles. FIG. 22C is an EDX image of elemental sulfur derived from the conductive resin. As in FIG. 22B, particle boundaries are indicated by dashed lines. A conductive resin is present in contact with the inner surfaces of the gaps P1d, i.e., the inner surfaces of the active material particles. Furthermore, a conductive resin is also present in contact with the outer surfaces of the LCO particles, and is arranged to connect the LCO particles. FIG. 22D is an EDX image of boron element derived from the solid electrolyte LBO. As in FIG. 22B, particle boundaries are indicated by dashed lines. As can be seen from FIGS. 22C and 22D, the conductive resin and inorganic electrolyte are unevenly distributed between the LCO particles.

[0216] FIG. 23 is a low-magnification electron microscope image of the cross section of positive electrode A-1. FIG. 23A is an electron microscope image. FIG. 23B identifies LCO particles based on an EDX image (element Co), with particle boundaries indicated by dashed lines. FIG. 23C is an EDX image (element Co), FIG. 23D is an EDX image (element C), and FIG. 23E is an EDX image (element B). In FIGS. 23C to 23E, the boundaries of the LCO particles are indicated by dashed lines. A conductive resin is present in contact with the inner surface of the gap P1d, i.e., the inner surface of the active material particles. Furthermore, a conductive resin is present in contact with the outer surface of the LCO particles, and is arranged to connect the LCO particles. Furthermore, the conductive resin is present so as to overlap the region containing LBO.

[0217] 24A to 24C are schematic diagrams illustrating features of the present disclosure, for example, in Example 1. FIG. 24A is a schematic diagram of an electrode, and FIG. 24B shows the EDX element distribution along line A-A' in FIG. 24A. FIG. 24C shows the EDX element distribution along line B-B' in FIG. 24A. As shown in FIGS. 24A to 24C, the conductive resin is disposed in contact with the outer surfaces of the active material particles and connects the active material particles. It is believed that this forms a good interface with the active material particles as well as with the supporting electrolyte particles, improving ion diffusion within the electrode. Furthermore, it is believed that the conductive resin changes shape in response to the expansion and contraction of the active material particles during charging and discharging, thereby suppressing a decrease in ionic conductivity and electronic conductivity. Furthermore, it is believed that the voids within the electrode function as a space for deformation, including expansion and contraction of the conductive resin in response to the expansion and contraction of the active material particles.

[0218] The conductive resin is also filled in the gaps P1d within the LCO particles. That is, it is positioned so as to contact the inner surfaces of the LCO particles. In this way, the conductive resin forms a good interface with the LCO particle surfaces having the protrusions P1c, and also forms a good interface with the gaps P1d within the LCO particles, which is thought to further improve ion diffusion within the electrode. Furthermore, by filling the LCO particles with a flexible conductive resin, the shape changes in response to the expansion and contraction of the active material particles during charge and discharge. As a result, it is thought that a decrease in ionic conductivity and electronic conductivity within the particles is suppressed. Furthermore, it is thought that the conductive resin in contact with the inner and outer surfaces of the active material particles deforms in response to the expansion and contraction of the active material particles during charge and discharge, so as to connect discontinuities within the active material particles (e.g., cracks and gaps) and discontinuities between particles (e.g., voids) within the active material particles, thereby maintaining ionic conductivity.

[0219] <Cross-sectional observation of positive electrode> To observe the cross-section of the positive electrode, the battery was disassembled so as to separate it in the stacking direction, and the positive electrode was removed. The removed positive electrode was cut with a wire saw (DWS3400 / wire diameter 170 μm, diamond diameter 30 μm). 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. The cross-section was photographed with an electron microscope (ULTRA55), and a BIB-SEM image was obtained. The conditions were as follows: Detector: ESB (backscattered electron image) Observation conditions: accelerating voltage 3 kV Magnification: 1000x Filter: 1500 V bias applied to the ESB filter

[0220] Next, elemental mapping was performed using SEM-EDX (XFlash Detector 630M manufactured by Bruker Corp.) From the elemental mapping results, the active material particles, electrolyte particles, and conductive resin were identified.

[0221] The evaluation method for the secondary battery will be described below. <Charge-Discharge Characteristics Capacity Retention Rate> The mass M (g / cm) of the active material particles per unit area of ​​the resin substrate on which the particle layer is formed is ２) to calculate the mass of the positive electrode active material particles (M × number of layers × positive electrode area cm ２ ) was calculated. The active material particle mass M per unit area was determined as follows. The weight of the first substrate 11a was measured after the first particles P1 were filled by the first filling device 24a in the particle arrangement device 1. Next, the weight of the first substrate 11a was measured after the above-mentioned first particles P1 were transferred to the second substrate 11b. The difference was calculated to determine the mass of the first particles P1 on the second substrate 11b. Then, the active material particle mass M per unit area was calculated by dividing the mass of the first particles P1 by the area of ​​the second substrate 11b (the area of ​​the uneven region).

[0222] Another calculation method is to use ICP emission spectroscopy. The active material particle mass per unit area M (g / cm) is calculated in advance by the above-mentioned method or the like. ２ Three levels of resin substrates on which particle layers with clearly defined Co atoms are formed are prepared. These resin substrates are dissolved by microwave acid decomposition (ETHOS PRO), and the acid decomposition solution is diluted with ultrapure water. Then, ICP-AES measurement (CIROS CCD) is performed to quantify the Co element. 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) per unit area of ​​the resin substrate on which the particle layer to be measured is formed can be calculated. ２ ) can be obtained.

[0223] The current value at a current rate of 0.4 C was determined, and charge / discharge measurements (constant current charge / constant current discharge) were performed at a current rate of 0.4 C. The measurements were performed using a charge / discharge device (manufactured by Biologic). Figure 21 shows the measured charge / discharge curves. The vertical axis represents the battery cell voltage (V vs. Li / Li ＋ ), and the horizontal axis represents the battery cell capacity (mAh / g). The capacity is the capacity per mass of the positive electrode active material. 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). The capacity retention rate at this time is the ratio of the discharge capacity to the charge capacity (discharge capacity / charge capacity × 100%). The above measurement was repeated five times, and the average value was calculated. A value of 80% or more was considered good.

[0224] <Cycle Characteristics> Cycle evaluation (repeated charge / discharge measurement in constant current mode) was performed at a current rate of 0.4 C. Repeated charge / discharge measurements were performed on the above-mentioned capacity retention rate until the capacity retention rate reached 80% or less, and the number of cycles n was calculated. A battery with 10 or more cycles was considered good. As a result of the battery evaluation, the capacity retention rate was 100%, and the number of cycles n was 12. When the charge / discharge characteristics and cycle characteristics were good according to the above evaluation, the battery was rated as A (Table 1).

[0225] Example 2 A positive electrode A-2 was prepared in the same manner as in Example 1, except that the filler material was applied to the particle-arranged surface of the positive electrode precursor and filled into the positive electrode precursor. A secondary battery SB-2 was also prepared in the same manner as in Example 1, except that the positive electrode A-2 was used. When a cross-section of the positive electrode A-2 was observed, it was found that, similar to the positive electrode A-1, the conductive resin was located so as to contact the inner surface of the gap. Similarly to the positive electrode A-1, the conductive resin was located so as to contact the outer surface of the LCO particles and connect the LCO particles. Similarly to the positive electrode A-1, the conductive resin was present so as to overlap the region containing LBO. Furthermore, the conductive resin and the inorganic electrolyte were unevenly distributed between the LCO particles. Furthermore, it was confirmed that the resulting secondary battery SB-2 had good capacity retention and cycle characteristics, similar to the secondary battery SB-1.

[0226] Example 3 A positive electrode A-3 was prepared in the same manner as in Example 1, except that the sintering temperature in the third step was changed from 510°C to 700°C. A secondary battery SB-3 was also prepared in the same manner as in Example 1, except that the positive electrode A-3 was used. FIGS. 25A to 25C are electron microscope images of the cross section of the positive electrode A-3. FIG. 25A is an electron microscope image, FIG. 25B is an EDX image (element C), and FIG. 25C is an EDX image (element B). Perhaps due to the high temperature sintering, oxidation of the LCO particles progressed, returning them to a form similar to that of the raw LCO particles, and no interstices were observed. In the cross-sectional structure of the obtained positive electrode A-3, the conductive resin was in contact with the outer surfaces of the LCO particles and was arranged to connect the LCO particles. Furthermore, similar to positive electrode A-1, the conductive resin was present so as to overlap the region containing LBO. Furthermore, the conductive resin and the inorganic electrolyte were unevenly distributed between the LCO particles. Furthermore, it was confirmed that the obtained secondary battery SB-3 had good capacity retention and cycle characteristics, similar to the secondary battery SB-1.

[0227] Example 4 A positive electrode A-4 was produced in the same manner as in Example 1, except that the first particles were changed to LCO (CellSeed C-8H) having a large particle size. When a cross-section of the positive electrode A-4 was observed, it was found that, similar to the positive electrode A-1, the conductive resin was located so as to contact the inner surface of the gap. Furthermore, similar to the positive electrode A-1, the conductive resin was located so as to contact the outer surface of the LCO particles and connect the LCO particles. Furthermore, similar to the positive electrode A-1, the conductive resin was present so as to overlap the region containing LBO. Furthermore, the conductive resin and the inorganic electrolyte were unevenly distributed between the LCO particles. Furthermore, it was confirmed that the resulting secondary battery SB-4 had good capacity retention and cycle characteristics, similar to the secondary battery SB-1.

[0228] Example 5 A positive electrode A-5 was produced in the same manner as in Example 1, except that pressure (50 MPa) was applied by the pressure means 422 in the sintering treatment apparatus U4. When a cross-section of the positive electrode A-5 was observed, it was found that, similar to the positive electrode A-1, the conductive resin was located so as to contact the inner surface of the gap. Also, similar to the positive electrode A-1, the conductive resin was located so as to contact the outer surface of the LCO particles and connect the LCO particles. Furthermore, similar to the positive electrode A-1, the conductive resin was present so as to overlap the region containing LBO. Furthermore, the conductive resin and the inorganic electrolyte were unevenly distributed between the LCO particles. Furthermore, it was confirmed that the resulting secondary battery SB-5 had good capacity retention and cycle characteristics, similar to the secondary battery SB-1.

[0229] Example 6: Li as electrolyte particles ５．９ Yb ０．８１ La ０．０９ Zr ０．１ (BO ３ ) ３ A positive electrode A-6 was prepared in the same manner as in Example 1, except that (LYbBO-1) was used. A secondary battery SB-6 was prepared in the same manner as in Example 1, except that the positive electrode A-6 was used. When a cross-section of the positive electrode A-6 was observed, it was found that, similar to the positive electrode A-1, the conductive resin was located so as to contact the inner surface of the gap. Similarly to the positive electrode A-1, the conductive resin was located so as to contact the outer surface of the LCO particles and connect the LCO particles. Furthermore, similar to the positive electrode A-1, the conductive resin was present so as to overlap the region containing LBO. Furthermore, the conductive resin and the inorganic electrolyte were unevenly distributed between the LCO particles. Furthermore, it was confirmed that the obtained secondary battery SB-6 had good capacity retention and cycle characteristics, similar to the secondary battery SB-1.

[0230] Table 1 shows a comparison table summarizing the formulations and production conditions of Examples 1 to 6 and the evaluation results. In the table, the application location indicates the location where the filler material was applied to the positive electrode precursor in step 3-1, the contact location indicates the contact location between the conductive resin and the LCO particles, and the presence or absence of co-distribution indicates whether the conductive resin and the inorganic electrolyte are co-distributed unevenly.

[0231] 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. 2023-131271, filed August 10, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. An electrode for use in a secondary battery, the electrode comprising active material particles and a conductive resin, the active material particles having an inner surface, and the conductive resin being positioned so as to be in contact with the inner surface.

2. The electrode according to claim 1, wherein the conductive resin includes a resin having ionic conductivity.

3. The electrode according to claim 1 or 2, wherein the conductive resin comprises a resin containing an ionic functional group and a supporting electrolyte.

4. The electrode according to any one of claims 1 to 3, wherein the conductive resin comprises a urethane resin containing an ionic functional group and a supporting electrolyte.

5. An electrode according to any one of claims 1 to 4, wherein the inner surface is continuous with the outer surface of the active material particles.

6. The electrode according to claim 5, wherein the conductive resin is in contact with the outer surface.

7. The electrode according to any one of claims 1 to 6, further comprising at least one selected from the group consisting of a conductive resin, a conductive assistant, and a supporting electrolyte between the active material particles.

8. The electrode according to any one of claims 1 to 7, further comprising a supporting electrolyte between the active material particles, the supporting electrolyte including an inorganic electrolyte.

9. The electrode according to claim 8, wherein the regions between said particles containing said conductive resin overlap with the regions between said particles containing said inorganic electrolyte.

10. The electrode according to any one of claims 1 to 9, wherein the active material particles comprise lithium cobalt oxide.

11. The electrode according to claim 5 or 6, wherein the active material particles have protrusions protruding from the outer surface.

12. The electrode according to any one of claims 1 to 11, wherein the conductive resin contains at least one of polyurethane, polyacrylic, and polyether in its main chain structure.

13. An electrode according to any one of claims 1 to 12, wherein the conductive resin contains polyether, which is a copolymer of polyethylene glycol and polypropylene glycol, in its main chain structure.

14. The electrode according to any one of claims 1 to 13, wherein the conductive resin has higher flexibility than the active material particles.

15. An electrode for use in a secondary battery, the electrode comprising active material particles and a conductive resin, the active material particles having an outer surface, and the resin being disposed in contact with the outer surface and connecting the active material particles.

16. The electrode according to claim 15, wherein the conductive resin includes an ionic conductive resin.

17. The electrode according to claim 15 or 16, wherein the conductive resin contains at least one of polyurethane, polyacrylic, and polyether in its main chain structure.

18. An electrode according to any one of claims 15 to 17, wherein the conductive resin contains polyether, which is a copolymer of polyethylene glycol and polypropylene glycol, in its main chain structure.

19. The electrode according to any one of claims 15 to 18, wherein the active material particles have an inner surface, the inner surface being continuous with the outer surface.

20. The electrode according to claim 19, wherein the conductive resin is positioned so as to contact the inner surface.

21. The electrode according to any one of claims 15 to 20, further comprising a supporting electrolyte between the active material particles, the supporting electrolyte including an inorganic electrolyte.

22. The electrode according to claim 21, wherein the regions between said particles containing said conductive resin overlap with the regions between said particles containing said inorganic electrolyte.

23. An electrode composite comprising an electrode and an electrolyte layer that transfers active material between the electrode and the electrolyte layer, wherein the electrode is the electrode according to any one of claims 1 to 22.

24. A secondary battery including a positive electrode and an electrolyte layer which transfers active material between said positive electrode and said electrolyte layer, wherein said positive electrode is an electrode according to any one of claims 1 to 22, and said secondary battery includes a negative electrode which transfers active material between said electrolyte layer and said positive electrode.

25. A method for manufacturing an electrode, comprising: a 1-1 step of preparing an electrode precursor containing active material particles and having gaps between the active material particles; a 2-1 step of preparing a filler material to be filled into the electrode precursor; a 3-1 step of filling the filler material from the outside to the inside of the electrode precursor; and a 4-1 step of retaining the filler material filled inside the electrode precursor.

26. The method for producing an electrode according to claim 25, wherein the 3-1 step includes a penetration step of penetrating the filler material into the inside of the electrode precursor so as to contact the outer surfaces of the active material particles.

27. The method for producing an electrode according to claim 25 or 26, wherein step 1-1 includes a step of forming an inner surface on the active material particles.

28. The method of claim 27, wherein the step of forming an inner surface on the active material particles comprises sintering the active material particles.

29. A method for manufacturing an electrode according to any one of claims 25 to 28, wherein the step 1-1 includes: a first step of forming a particle layer containing active material particles and electrolyte particles on a resin substrate having an adhesive portion; a second step of forming a laminate by stacking a plurality of resin substrates on which the particle layer has been formed; a third step of removing the resin substrate from the laminate to form a three-dimensional object containing active material particles and electrolyte particles; and a fourth step of post-treating the three-dimensional object.

30. A method for producing an electrode described in any one of claims 25 to 29, wherein the 3-1 step includes a penetration step of penetrating the filler material into the inside of the electrode precursor so as to contact the inner surfaces of the active material particles.

31. The method for manufacturing an electrode according to any one of claims 25 to 30, wherein the electrode precursor has an end portion, and step 3-1 includes applying the filling material to the end portion of the electrode precursor.

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