Electrode and method for manufacturing the same

Abstract

To provide an electrode excellent in cycle characteristics and rate characteristics.SOLUTION: An electrode has a substrate, and an electrode mixture layer provided on the substrate. The electrode mixture layer includes an active material, and a binder. The concentration of the binder in the electrode mixture layer is periodically and continuously made different in at least one direction orthogonal to a thickness direction of the electrode mixture layer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an electrode and a method for manufacturing the same. [Background technology]

[0002] In recent years, the range of applications of electrochemical elements such as lithium ion secondary batteries, electric double layer capacitors, lithium ion capacitors, and redox capacitors has been rapidly expanding, from small consumer devices such as wearable devices and smartphones to large devices such as electric vehicles and stationary storage batteries. In response to the diversifying needs of electrochemical elements, there is a need for a new method for manufacturing electrodes that allows flexible switching between different types of electrodes.

[0003] For example, in order to prevent the electrode active material from falling off from the substrate or the electrode mixture layer and thus losing capacity during repeated charge and discharge, an electrode mixture layer has been proposed in which the binder concentration in the electrode mixture layer is intentionally changed. More specifically, a positive electrode for a nonaqueous electrolyte secondary battery has been proposed in which the binder concentration in the positive electrode mixture layer is made higher near the current collector, and forced drying has been used to make the binder concentration near the surface of the positive electrode mixture layer higher than that in the center, and the binder concentration in the center between the current collector and the electrode surface is 50 to 90% of the binder concentration near the current collector (see, for example, Patent Document 1). Furthermore, an electrode for a lithium ion secondary battery has been proposed, which has a current collector and an electrode layer formed on the surface of the current collector and containing a binder resin, an active material, and a conductive additive, in which the electrode layer comprises a first electrode layer and a second electrode layer having a binder resin concentration higher than the binder resin concentration of the first electrode layer, the first electrode layer being disposed on the surface of the current collector, and the second electrode layer being disposed at least on the surface of the current collector so as to be in contact with the surface of the current collector and at least the side surface of the first electrode layer (see, for example, Patent Document 2). Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide an electrode that is excellent in cycle characteristics and rate characteristics. [Means for solving the problem]

[0005] The electrode of the present invention as a means for solving the problems is a substrate; an electrode having an electrode mixture layer provided on a substrate, the electrode mixture layer contains an active material and a binder, The binder concentration in the electrode mixture layer is characterized by varying periodically and continuously in at least one direction perpendicular to the thickness direction of the electrode mixture layer. [Effects of the Invention]

[0006] According to the present invention, an electrode having excellent cycle characteristics and rate characteristics can be provided. [Brief explanation of the drawings]

[0007] [Figure 1A] FIG. 1A is a schematic cross-sectional view showing an electrode according to one embodiment of the present invention. [Figure 1B] FIG. 1B is a schematic cross-sectional view illustrating a binder concentration gradient in an electrode according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an electrode according to another embodiment of the present invention. [Figure 3] FIG. 3 is a schematic cross-sectional view showing an electrode according to another embodiment of the present invention. [Figure 4] FIG. 4 is an example of an image after binarization processing in the method for measuring the average porosity of an electrode mixture layer. [Figure 5] FIG. 5 is a schematic cross-sectional view showing an electrode according to another embodiment of the present invention. [Figure 6A] FIG. 6A is a schematic cross-sectional view showing an electrode according to another embodiment of the present invention. [Figure 6B] FIG. 6B is a schematic cross-sectional view showing an electrode according to another embodiment of the invention. [Figure 7] FIG. 7 is a schematic diagram showing an electrode manufacturing apparatus according to one embodiment of the present invention. [Figure 8] FIG. 8 is a schematic diagram showing an electrode manufacturing apparatus according to another embodiment of the present invention. [Figure 9] FIG. 9 is a schematic diagram showing an electrode manufacturing apparatus according to another embodiment of the present invention. [Figure 10] FIG. 10 is a schematic diagram showing a modified example of an electrode manufacturing apparatus according to one embodiment of the present invention. [Figure 11] FIG. 11 is a structural diagram (part 1) showing an example of a printing unit that employs an inkjet system and a transfer system as a means for applying a liquid composition for forming an electrode composite layer in an electrode manufacturing apparatus according to one embodiment of the present invention. [Figure 12] Figure 12 is a structural diagram (part 2) showing an example of a printing unit that employs an inkjet method and a transfer method as a means for applying a liquid composition for forming an electrode composite layer in an electrode manufacturing apparatus according to one embodiment of the present invention. [Figure 13] FIG. 13 is a schematic diagram showing an example of a formation pattern of an electrode mixture layer in a method for producing an electrode according to one embodiment of the present invention. [Figure 14] FIG. 14 is a schematic diagram showing another example of a formation pattern of an electrode mixture layer in a method for producing an electrode according to one embodiment of the present invention. [Figure 15] FIG. 15 is a schematic diagram showing another example of a formation pattern of an electrode mixture layer in a method for producing an electrode according to one embodiment of the present invention. [Figure 16] FIG. 16 is a schematic diagram showing another example of a formation pattern of an electrode mixture layer in a method for producing an electrode according to one embodiment of the present invention. [Figure 17] FIG. 17 is a schematic cross-sectional view showing an electrochemical device according to one embodiment of the present invention. [Figure 18] FIG. 18 is a schematic cross-sectional view showing an electrochemical device according to another embodiment of the present invention. [Figure 19] FIG. 19 is a schematic diagram showing a mobile body that is an electrochemical device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] In conventional electrodes including those described in Patent Document 1, regions with high binder concentrations are concentrated at the substrate / electrode mixture layer interface and the electrode mixture layer surface, resulting in relatively high electronic resistance at the substrate / electrode mixture layer interface and relatively high solution resistance at the electrode mixture layer surface, making them unsuitable for applications requiring rapid charging and discharging. Furthermore, when the amount of binder added to the active material is small or when an active material with a large volume expansion change rate is used, there is concern that binder peeling may occur in layers with low binder concentrations. Patent Document 2 proposes a technology to address the issues of Patent Document 1. However, because a first electrode layer with a low binder concentration and a second electrode layer with a high binder concentration are used, the binder concentration changes discontinuously at their interface, which causes non-uniform current density and makes Li dendrites more likely to occur. As a result, sufficient cycle characteristics cannot be obtained, and there is room for improvement.

[0009] The electrode of the present invention has a substrate and an electrode mixture layer provided on the substrate, the electrode mixture layer containing an active material and a binder, and the binder concentration in the electrode mixture layer varies periodically and continuously in at least one direction perpendicular to the thickness direction of the electrode mixture layer. This configuration can sufficiently resolve various concerns in the prior art. More specifically, it can realize an electrode with excellent cycle characteristics and rate characteristics.

[0010] The present invention will be described in detail below.

[0011] (electrode) The electrode of the present invention has a substrate and an electrode mixture layer, and may contain other members as necessary.

[0012] Here, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In each drawing, the same components are denoted by the same reference numerals, and redundant explanations may be omitted. Furthermore, the number, position, shape, etc. of the components are not limited to the present embodiment, and the number, position, shape, etc. may be any number, position, shape, etc. that is preferable for implementing the present invention.

[0013] [Figure 1A] FIG. 1A is a schematic cross-sectional view showing an electrode according to one embodiment of the present invention. As shown in FIG. 1A, the electrode has a substrate 1 and an electrode mixture layer 2 provided on the substrate 1.

[0014] <Base> The substrate in the present invention is not particularly limited as long as it has electron conductivity and is stable to an applied potential, and can be appropriately selected depending on the purpose. Examples include aluminum foil, copper foil, stainless steel foil, titanium foil, etched foil obtained by etching these foils to form fine holes, carbon-coated foil whose surface is coated with a carbon-containing resin layer, foil coated with a PTC (Phase-Transfer Catalyst) layer, and perforated substrates used in lithium ion capacitors. In this specification, a substrate used for a negative electrode may be referred to as a "negative electrode substrate" or a "negative electrode substrate", and a substrate used for a positive electrode may be referred to as a "positive electrode substrate" or a "positive electrode substrate".

[0015] <Electrode composite layer> The electrode mixture layer in the present invention contains an active material and a binder, and may contain a conductive aid and other components as necessary.

[0016] <<Active material>> The active material may be a positive electrode active material or a negative electrode active material. The positive electrode active material or the negative electrode active material may be used alone or in combination of two or more.

[0017] -Cathode active material- The positive electrode active material is not particularly limited and can be appropriately selected depending on the purpose as long as it is a material that can reversibly absorb and release alkali metal ions, and examples thereof include alkali metal-containing transition metal compounds. Examples of alkali metal-containing transition metal compounds include lithium-containing transition metal compounds such as composite oxides containing lithium and one or more elements selected from the group consisting of cobalt, manganese, nickel, chromium, iron, and vanadium. Examples of lithium-containing transition metal compounds include lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide.

[0018] As the alkali metal-containing transition metal compound, a polyanion compound having an XO4 tetrahedron (X=P, S, As, Mo, W, Si, etc.) in the crystal structure can be used. Among these, lithium-containing transition metal phosphate compounds such as lithium phosphate and lithium vanadium phosphate are preferred from the viewpoint of cycle characteristics, and lithium vanadium phosphate is preferred from the viewpoint of lithium diffusion coefficient and output characteristics. When a polyanion compound is used, it is preferable that the surface of the polyanion compound is coated with a conductive aid such as a carbon material to form a composite, in terms of electron conductivity.

[0019] The alkali metal-containing transition metal compound preferably has at least a portion of its surface coated with an ion-conductive oxide, preferably a lithium ion-conductive oxide. The lithium ion conductive oxide is not particularly limited and can be appropriately selected depending on the purpose. For example, x AO y (A is B, C, Al, Si, P, S, Ti, Zr, Nb, Mo, Ta, Sc, V, Y, Ca, Sr, Ba, Hf, Ta, Cr, or W, and x and y are positive numbers.) Specific examples of lithium ion conductive oxides include Li3BO3, LiBO2, Li2CO3, LiAlO2, Li4SiO4, Li2SiO3, Li3PO4, Li2SO4, Li2TiO3, and Li4Ti5O. 12 , Li2Ti2O5, Li2ZrO3, LiNbO3, LiTaO3, Li2MoO4, and Li2WO4. Among these, Li4Ti5O 12 , Li2ZrO3, or LiNbO3 are preferred. The lithium ion conductive oxide may be a composite oxide, which may be any combination of lithium ion conductive oxides, such as Li4SiO4-Li3BO3 and Li4SiO4-Li3PO4.

[0020] -Negative electrode active material- The negative electrode active material is not particularly limited as long as it is a material that can reversibly absorb and release alkali metal ions and can be appropriately selected depending on the purpose. For example, a carbon material containing graphite having a graphite-type crystal structure can be used. Examples of carbon materials include natural graphite, spherical or fibrous artificial graphite, non-graphitizable carbon (hard carbon), and easily graphitizable carbon (soft carbon). Examples of materials other than carbon materials include lithium titanate and titanium oxide. From the viewpoint of increasing the energy density of a lithium ion secondary battery, high capacity materials such as silicon, tin, silicon alloys, tin alloys, silicon oxide, silicon nitride, and tin oxide can also be suitably used as the negative electrode active material.

[0021] The mode diameter of the active material is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.5 μm or more and 20 μm or less, and more preferably 3 μm or more and 10 μm or less. When the mode diameter of the active material is 0.5 μm or more and 20 μm or less, an electrode with better battery characteristics is likely to be obtained, and when the mode diameter of the active material is 3 μm or more and 10 μm or less, an electrode with particularly good battery characteristics is obtained. In this specification, the diameter at the maximum value of the particle size distribution of the active material in the liquid composition for forming an electrode mixture layer was calculated as the mode diameter.

[0022] The method for measuring the mode diameter of the active material is not particularly limited and can be appropriately selected depending on the purpose. For example, the measurement can be performed in accordance with ISO 13320:2009. The device used for the measurement is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a laser diffraction particle size distribution measuring device (Mastersizer 3000, manufactured by Malvern Instruments).

[0023] The maximum particle size Dmax of the active material is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 40 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. When the maximum particle diameter Dmax of the active material is 40 μm or less, convex portions due to unintended coarse active material are unlikely to be formed in the obtained electrode mixture layer, and the risk of short circuits when an insulating layer such as a separator is laminated can be reduced. Furthermore, even when a pressing process is performed, damage to the active material due to localized stress applied to the convex portions can be reduced.

[0024] The method for measuring the maximum particle diameter Dmax of the active material is not particularly limited and can be appropriately selected depending on the purpose. For example, the measurement can be performed in accordance with ISO 13320:2009. The device used for the measurement is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a laser diffraction particle size distribution measuring device (Mastersizer 3000, manufactured by Malvern Instruments).

[0025] The median diameter D50 of the active material is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.5 μm or more and 20 μm or less, and more preferably 3 μm or more and 10 μm or less. When the median diameter D50 of the active material is 0.5 μm or more and 20 μm or less, an electrode with better battery characteristics is likely to be obtained. Also, when the median diameter D50 of the active material is 3 μm or more and 10 μm or less, an electrode with particularly good battery characteristics is obtained.

[0026] The method for measuring the median diameter D50 of the active material is not particularly limited and can be appropriately selected depending on the purpose. For example, the measurement can be performed in accordance with ISO 13320:2009. The device used for the measurement is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a laser diffraction particle size distribution measuring device (Mastersizer 3000, manufactured by Malvern Instruments).

[0027] <<Binder>> The binder is not particularly limited and can be appropriately selected depending on the purpose as long as it can bind negative electrode materials together, positive electrode materials together, a negative electrode material and a negative electrode substrate, or a positive electrode material and a positive electrode substrate. When the electrode mixture layer-forming liquid composition is used for inkjet ejection, it is preferable that the binder does not easily increase the viscosity of the electrode mixture layer-forming liquid composition, from the viewpoint of suppressing nozzle clogging of the liquid ejection head.

[0028] As the binder, a polymer compound can be used. Examples of polymer compounds include thermoplastic resins such as polyvinylidene fluoride (PVDF), acrylic resin, polyethylene, polypropylene, polyurethane, nylon, polytetrafluoroethylene, polyphenylene sulfide, polyethylene terephthalate, and polybutylene terephthalate, polyamide compounds, polyimide compounds, polyamideimide, ethylene-propylene-butadiene rubber (EPBR), styrene-butadiene rubber (SBR), nitrile butadiene rubber (NBR), isoprene rubber, polyisobutene, and polyethylene. Examples of such polymers include polyethylene glycol (PEO), polymethylmethacrylate (PMMA), polyethyl methacrylate (PEMA), polybutyl methacrylate (PBMA), polyethylene vinyl acetate (PEVA), poly2-(dimethylamino)ethyl methacrylate, poly2-(diethylamino)ethyl methacrylate, poly(2-(dimethylamino)ethyl methacrylate-polybutyl methacrylate) copolymer, poly(2-(diethylamino)ethyl methacrylate-polybutyl methacrylate) copolymer, and carboxymethyl cellulose.

[0029] The content of the binder relative to the active material is not particularly limited and can be set appropriately depending on the purpose, but is preferably 0.5% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass or less, and even more preferably 1.5% by mass or more and 5% by mass or less. If the content of the binder relative to the active material is 0.5% by mass or more, the active material can be firmly bound to the substrate, which is preferable.

[0030] <<Conductive additives>> The conductive additive is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include carbon black produced by a furnace method, an acetylene method, a gasification method, etc., and carbon materials such as carbon nanofibers, carbon nanotubes, graphene, and graphite particles. Examples of the conductive additive other than the carbon material include metal particles such as aluminum, metal fibers, etc. The conductive additive may be previously compounded with the active material.

[0031] The content of the conductive additive relative to the active material is not particularly limited and can be set appropriately depending on the purpose, but is preferably 10% by mass or less, and more preferably 8% by mass or less. The upper limit of the mass ratio of the conductive additive to the active material is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. When the mass ratio of the conductive additive to the active material is the upper limit or less, the conductivity of the obtained electrode mixture layer is not impaired and the energy density can be further improved. The mass ratio of the conductive additive to the active material is preferably at least 1 mass % as a lower limit. When the mass ratio of the conductive additive to the active material is at least the lower limit, the conductivity of the obtained electrode mixture layer is further improved.

[0032] <<Other ingredients>> The other components are not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include dispersants, solid electrolytes, surfactants, pH adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, antireducing agents, evaporation promoters, chelating agents, and thickeners.

[0033] <<<Dispersant>>> The dispersant is not particularly limited and can be appropriately selected depending on the purpose as long as it can improve the dispersibility of the active material in the liquid composition for forming an electrode mixture layer, and examples thereof include polymer dispersants such as carboxymethyl cellulose, polyethylene, polyethylene oxide, polypropylene oxide, polycarboxylic acid, naphthalenesulfonic acid-formalin condensation, polyethylene glycol, polycarboxylic acid partial alkyl ester, polyether, and polyalkylene polyamine; low molecular weight dispersants such as alkyl sulfonic acid, quaternary ammonium, higher alcohol alkylene oxide, polyhydric alcohol ester, and alkyl polyamine; and inorganic dispersants such as polyphosphate dispersants. Among these, dispersants having an ionic adsorption group are preferred from the viewpoint of dispersibility.

[0034] <<<Solid electrolyte>>> The solid electrolyte is not particularly limited and can be appropriately selected depending on the purpose as long as it exhibits electronic insulation and ion conductivity and does not react with the dispersion medium, and examples thereof include oxide solid electrolytes, sulfide solid electrolytes, etc. Among these, sulfide solid electrolytes are preferred from the viewpoint of having high plasticity and being able to form good interfaces between solid electrolyte particles or between the solid electrolyte and the active material, and crystalline argyrodite-type sulfide solid electrolytes are more preferred from the viewpoint of obtaining an excellent dispersion effect similar to that of the active material.

[0035] Examples of oxide solid electrolytes include compounds that contain oxygen atoms, have the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and have electronic insulation properties. In this specification, "having electronic insulation properties" means that when a positive electrode and a negative electrode are placed opposite each other with a solid electrolyte layer interposed therebetween, no short circuit occurs. In this specification, "exhibiting ion conductivity" means that when a positive electrode and a negative electrode are placed opposite each other with a solid electrolyte layer interposed therebetween, only ions move when a potential difference is applied.

[0036] Specific examples of oxide solid electrolytes include Li xa La ya TiO3 [xa=0.3~0.7, ya=0.3~0.7] (LLT), Li xb La yb Zr zb Mbb mb O nb (Mbb is at least one element selected from Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, and Sn, xb satisfies 5≦xb≦10, yb satisfies 1≦yb≦4, zb satisfies 1≦zb≦4, mb satisfies 0≦mb≦2, and nb satisfies 5≦nb≦20), Li xc B yc Mcc zc O nc (Mcc is at least one element selected from C, S, Al, Si, Ga, Ge, In, and Sn, xc satisfies 0≦xc≦5, yc satisfies 0≦yc≦1, zc satisfies 0≦zc≦1, and nc satisfies 0≦nc≦6), Lixd (Al,Ga) yd (Ti,Ge) zd Si ad P md O nd (where 1≦xd≦3, 0≦yd≦1, 0≦zd≦2, 0≦ad≦1, 1≦md≦7, 3≦nd≦13), Li(3-2xe)Mee xe DeeO (where xe represents a number of 0 or more and 0.1 or less, Mee represents a divalent metal atom, and Dee represents a halogen atom or a combination of two or more halogen atoms), Li xf Si yf O zf (1≦xf≦5, 0 <yf≦3、1≦zf≦10)、Li xg S yg O zg (1≦xg≦3, 0 <yg≦2、1≦zg≦10)、Li3BO3-Li2SO4、Li2O-B2O3-P2O5、Li2O-SiO2、Li6BaLa2Ta2O 12 , LiPO (4-3 / 2w) Nw (w<1), Li with LISICON (Lithium super ionic conductor) type crystal structure 3.5 Zn 0.25 GeO4, La with perovskite crystal structure 0.55 Li 0.35 TiO3, LiTi2P3O with NASICON (sodium super ionic conductor) type crystal structure 12 , Li 1+xh+yh (Al,Ga)xh(Ti,Ge) 2-xh Si yh P 3-yh O 12 (where 0≦xh≦1, 0≦yh≦1), Li7La3Zr2O with a garnet-type crystal structure 12 (LLZ) and others.

[0037] As the oxide solid electrolyte, a phosphorus compound containing Li, P, and O is also desirable. Examples include lithium phosphate (Li3PO4), LiPON in which some of the oxygen in lithium phosphate is substituted with nitrogen, and LiPOD1 (D1 is at least one selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, Au, etc.). LiAlON (Al is at least one selected from Si, B, Ge, Al, C, Ga, etc.) can also be preferably used.

[0038] Sulfide solid electrolytes can be roughly divided into, for example, crystalline sulfide solid electrolytes and glassy sulfide solid electrolytes.

[0039] Examples of crystalline sulfide solid electrolytes include Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , Li 9.6 P3S 12 , Li9P3S9O3, Li 9.81 Sn 0.81 P 2.19 S 12 , Li 9.42 Si 1.02 P 2.1 S 9.96 O 2.04 , Li 10 Ge(P 1-x Sb x )2S 12 (0≦x≦0.15), Li 10 SnP2S 12 , Li 10.35 [M1 1-x M2 x ] 1.35 P 1.65 S 12 (M1, M2 = Si, Ge, Sn, As, Sb, 0≦x≦0.15), Li 11 Si2PS 12 , Li 11 AlP2S 12 , Li 3.45 Si 0.45 P 0.55S4, Li6PS5X(X=Cl,Br,I), Li5PS4X2(X=Cl,Br,I), Li 5.5 PS 4.5 Cl 1.5 , Li 5.35 Ca 0.1 PS 4.5 Cl 1.55 , Li 6+x M x Sb 1-x S5I(M=Si,Ge,Sn, 0≦x≦1), Li7P2S8I, γ-Li3PS4, Li4MS4(M=Ge,Sn,As), Li 4-x Sn 1-x SbxS4(0≦x≦0.15), Li 4-x Ge 1-x PxS4(0≦x≦0.15), Li 3+5x P 1-x Examples include S4 (0≦x≦0.3).

[0040] Examples of glass-based sulfide solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-P2O5, Li2S-P2S5-LiCl, Li2S-SiS2, Li2S-SiS2-P2S5, Li2S-SiS2-Al2S3, and Li2S-SiS2-Li x MO y (M=Si, P, Ge), etc. In addition, Li7P3S, in which part of the glass-based sulfide solid electrolyte is crystallized, 11 Glass ceramics, etc. may also be used. Here, the mixing ratio of the raw materials for the glass-based sulfide solid electrolyte is not limited.

[0041] In the present invention, as shown in Fig. 1A, the binder concentration in the electrode mixture layer 2 varies periodically and continuously in at least one direction perpendicular to the thickness direction of the electrode mixture layer 2. More specifically, the average binder concentration C AVE In contrast, area A has a high binder concentration High and the average binder concentration C in the electrode mixture layer 2 AVE In contrast, in region A where the binder concentration is low Low It is preferable that the above-mentioned structures are present periodically and continuously.

[0042] In this specification, the term "region A with high binder concentration" refers to High and region A with low binder concentration Low The phrase "periodically exists" means that the average binder concentration C AVE Region A has a high binder concentration High and the average binder concentration C in the electrode mixture layer 2 AVE Region A where the binder concentration is low Low At this time, the electrode mixture layer has a region A at a constant pitch. High and area A Low It is preferred that the following are present: Here, the constant pitch is the area A High :Area A Low = 1:4 to 4:1, and more preferably approximately 1:1. Therefore, this is distinguished from changes in binder concentration that may occur when attempting to form a film with a uniform binder concentration.

[0043] In addition, in this specification, "region A with high binder concentration" High and region A with low binder concentration Low The phrase "are continuously present" means that the region A is continuously present in at least one direction perpendicular to the thickness direction of the electrode mixture layer 2. High From Area A Low This indicates that the binder concentration in the electrode mixture layer changes gradually over time, or vice versa. This is distinct from a case where the binder concentration changes stepwise (discontinuously), such as when two active material layers with different binder concentrations are adjacent to each other. In other words, this indicates that there is no boundary, or interface, where the binder concentration changes suddenly. There are no particular limitations on the method for determining whether the binder concentration in the electrode mixture layer is continuous or not, and the method can be appropriately selected depending on the purpose. Examples are shown below.

[0044] -Method A: When the binder contains characteristic elements- The base resin for 53-type embedding epoxy resin (Lot No. 53512040149, Sankei Co., Ltd.) and the curing agent (Lot No. 53572040342, Sankei Co., Ltd.) were thoroughly mixed in a volume ratio of 1:2, and the electrode composite layer was embedded in the resin using a vacuum impregnation device (Buehler Vacuum Impregnation Equipment I, Sankei Co., Ltd.) and allowed to cure for 24 hours. The electrode composite layer embedded in the epoxy resin was processed using a cross-section polisher (JEOL Ltd.), and the cross section was observed using a tabletop scanning electron microscope (SEM / EDX) (Phenom Prox, Jasco International Inc.) to perform elemental mapping of the cross section of the electrode composite layer. Even if the binder does not contain a characteristic element, if the binder can be stained by an electron staining method using osmium tetroxide or ruthenium tetroxide, element mapping can be performed by carrying out this method.

[0045] -Method B: When the binder does not contain characteristic elements- The electrode composite layer is cut using a surface and interface properties analyzer (SAICAS) at intervals 1 / 10 smaller than the period expected from the manufacturing method, and the collected samples are subjected to pyrolysis GC / MS analysis to obtain peak values ​​of fragments derived from the binder. This is applied to a calibration curve obtained using binders of known concentrations to quantify the binder concentration.

[0046] The period T of the binder concentration in the electrode mixture layer 2 is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of suppressing the detachment of the active material from the electrode mixture layer and the growth of Li dendrites and thereby obtaining excellent cycle characteristics, it is preferably 0.2 mm or more and 2.5 mm or less. Furthermore, from the viewpoint of efficiently binding the active material, it is preferably 0.4 mm or more, more preferably 0.6 mm or more, and is preferably 1.7 mm or less, and more preferably 1.3 mm or less. If the period T of the binder concentration in the electrode mixture layer 2 is 0.2 mm or more, the binding property will not change compared to an electrode having a uniform binder concentration, and the problem of not being able to obtain excellent effects such as cycle characteristics can be resolved. If the period T of the binder concentration in the electrode mixture layer 2 is 2.5 mm or less, it is possible to overcome the problem that the active material cannot be sufficiently bound in regions with low binder concentration. The period T of the binder concentration in the electrode mixture layer 2 may be defined as one period from a maximum value to an adjacent maximum value in the binder concentration distribution in the X direction or Y direction, or from a minimum value to an adjacent minimum value.

[0047] The method for measuring the period T of the binder concentration in the electrode mixture layer is not particularly limited and can be appropriately selected depending on the purpose. Examples are shown below.

[0048] -Method A: When the binder contains characteristic elements- The base resin (Lot No. 53512040149, Sankei Co., Ltd.) and curing agent (Lot No. 53572040342, Sankei Co., Ltd.) for 53-type embedding epoxy resin were thoroughly mixed in a volume ratio of 1:2. Using a vacuum impregnation device (Buehler Vacuum Impregnation Equipment I, Sankei Co., Ltd.), the electrode composite layer was embedded in the resin and allowed to cure for 24 hours. The electrode composite layer embedded in the epoxy resin was processed using a cross-section polisher (JEOL Ltd.), and the cross section was observed using a tabletop scanning electron microscope (SEM / EDX) (Phenom Prox, Jasco International Inc.) to perform elemental mapping of the cross section of the electrode composite layer. The period was calculated from the binder concentration distribution in the X or Y direction. Even if the binder does not contain a characteristic element, if the binder can be stained by an electron staining method using osmium tetroxide or ruthenium tetroxide, element mapping can be performed by carrying out this method.

[0049] -Method B: When the binder does not contain characteristic elements- The electrode composite layer is cut using a surface and interface characterization analyzer (SAICAS) at intervals 1 / 10 smaller than the period expected from the manufacturing method, and the collected samples are subjected to pyrolysis GC / MS analysis to obtain the peak value of the fragment derived from the binder. The binder concentration is quantified by applying this to a calibration curve obtained using binders of known concentration. The period is calculated by plotting the binder concentration in each sample.

[0050] [Figure 1B] The mechanism by which continuous and periodic changes in binder concentration occur in the electrode of the present invention will be explained with reference to FIG. 1B. FIG. 1B is a schematic cross-sectional view illustrating a binder concentration gradient in an electrode according to one embodiment of the present invention. Fig. 1B(a) is a schematic cross-sectional view showing the state immediately after the electrode mixture layer forming liquid composition is applied to the substrate 1. Fig. 1B(b) is a schematic cross-sectional view when the applied electrode mixture layer forming liquid composition has spread (leveled) and coalesced with adjacent droplets. Immediately after application of the electrode mixture layer-forming liquid composition, the solvent 3, active material 4, and binder 5 are uniformly dispersed in the droplets. Solid components in the electrode mixture layer-forming liquid composition settle over time according to the Stokes equation, which is determined by the particle size, specific gravity, and viscosity of the electrode mixture layer-forming liquid composition. The active material has a higher specific gravity and larger particle size than the binder contained in the electrode mixture layer-forming liquid composition, resulting in a faster settling rate. Therefore, in the electrode mixture layer-forming liquid composition applied to the substrate, the active material settles first and loses fluidity. Simultaneously, the electrode mixture layer-forming liquid composition spreads over the substrate and coalesces with adjacent droplets. When an inkjet is used as the liquid ejection method, the active material in the droplets ejected from the ejection heads tends to accumulate directly below the droplet ejection position, resulting in a relatively high binder concentration in the area between the ejection heads where the droplets coalesce. The loss of fluidity due to settling occurs continuously over time, and the binder concentration also changes continuously and periodically accordingly.

[0051] If the viscosity of the electrode mixture layer-forming liquid composition is too low, the electrode mixture layer-forming liquid composition, and in turn the active material in the electrode mixture layer-forming liquid composition, will immediately spread in the X or Y direction due to the impact of landing on the substrate, making it difficult for the active material to remain directly below the liquid ejection position, which may make it difficult to obtain an electrode mixture layer with a periodic binder concentration.In addition, there is also a risk that uneven drying due to heat transfer convection in the electrode mixture layer-forming liquid composition drying step will have an effect, making it impossible to obtain a periodic binder concentration distribution. Therefore, the viscosity (rotation speed: 100 rpm) of the liquid composition for forming an electrode mixture layer is preferably 20 cp or more, more preferably 30 cp or more, and particularly preferably 40 cp or more. The electrode mixture layer-forming liquid composition is preferably a thixotropic fluid. The thixotropy index of the liquid composition for forming an electrode mixture layer, defined as viscosity at 10 rpm / viscosity at 100 rpm, is preferably 1.2 or more, more preferably 1.5 or more, and particularly preferably 2.0 or more. The thixotropy index of the liquid composition for forming an electrode mixture layer is preferably 10 or less, more preferably 5 or less, from the viewpoint of eliminating problems such as a long waiting time until coalescence after impact, which reduces productivity.

[0052] In this specification, the average binder concentration in the electrode mixture layer is referred to as "C AVE " and Area A High The average binder concentration in High " and Area A Low The average binder concentration in Low ". In addition, C High and C Low are the average binder concentrations in each region in one cycle. where C Low C against High The ratio (C High / C Low) is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of improving cycle characteristics by efficient binding, it is preferably 1.2 or more, more preferably 1.5 or more, and even more preferably 2.0 or more. Also, from the viewpoint of suppressing the generation of Li dendrites, it is preferably 10 or less, more preferably 5 or less, and even more preferably 3 or less. Low C against High The ratio (C High / C Low ) is calculated by using the values ​​of each region from the same period.

[0053] [Figure 2] FIG. 2 is a schematic cross-sectional view showing an electrode according to another embodiment of the present invention. In this specification, region A High The average thickness at t High " and Area A Low The average thickness at t Low The average thickness t High and average thickness t Low is the average thickness of each region in one period. Region A in the electrode of the present invention High Average thickness t High and area A Low Average thickness t Low It is preferable that the formula (1) is satisfied. t High <t Low ...Equation (1)

[0054] When the average thickness of each region in the electrode of the present invention satisfies formula (1), an electrode with excellent cycle characteristics and rate characteristics can be obtained. The mechanism behind this is not clear, but is presumed to be as follows. The expansion and contraction of the active material caused by the charge and discharge reaction occurs in region A where the binder concentration, which acts as a resistance component, is low. Low Since the stress and strain inside the electrode mixture layer progress from region A High Focus on Area A HighSince the binder concentration is high, the region A can withstand stress strain relatively well. High The space formed in the upper part acts as a buffer layer to relieve stress strain, resulting in better cycle characteristics. The buffer layer also allows the electrolyte to penetrate more easily, resulting in better rate characteristics.

[0055] Region A in the electrode of the present invention High Average thickness t High and area A Low Average thickness t Low From the viewpoint of preventing damage to the electrode mixture layer, it is preferable that the change be continuous, and more preferably that the change be curved. The fact that the average thickness in each region A changes in a curved shape can be confirmed by obtaining a surface profile using, for example, a laser microscope or a stylus-type step gauge.

[0056] Average thickness t Low Average thickness t High The ratio (t High / t Low ) is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of preventing damage to the electrode mixture layer, it is preferably 0.5 or more, more preferably 0.7 or more. Also, from the viewpoint of efficiently relaxing stress strain, it is preferably 0.95 or less, more preferably 0.9 or less. Low Average thickness t High The ratio (t High / t Low ) are calculated using values ​​from the same period.

[0057] The method for measuring the average thickness of the electrode mixture layer is not particularly limited and can be appropriately selected depending on the purpose. Examples are shown below.

[0058] -Method A: When the binder contains characteristic elements- The base resin (Lot No. 53512040149, Sankei Co., Ltd.) and curing agent (Lot No. 53572040342, Sankei Co., Ltd.) of 53-type embedding epoxy resin were thoroughly mixed at a volume ratio of 1:2. Using a vacuum impregnation device (Buehler Vacuum Impregnation Equipment I, Sankei Co., Ltd.), the electrode composite layer was embedded in the resin and allowed to cure for 24 hours. The electrode composite layer embedded in the epoxy resin was processed using a cross-section polisher (JEOL Ltd.), and the cross section was observed using a tabletop scanning electron microscope (SEM / EDX) (Phenom Prox, Jasco International Inc.) to perform elemental mapping of the cross section of the electrode composite layer. Even if the binder does not contain characteristic elements, elemental mapping can be performed by performing electron staining using osmium tetroxide or ruthenium tetroxide if the binder can be stained using this method. The average binder concentration C across the entire cross section of the electrode composite layer was calculated. Ave , and the binder concentration in the X or Y direction is averaged in the thickness (Z) direction to calculate the average binder concentration C Ave Region A where the binder concentration is higher than High and low area A Low Divide into area A High The average thickness t High and area A Low The average thickness t Low and calculate.

[0059] -Method B: When the binder does not contain characteristic elements- The electrode composite layer is cut using a surface and interface characterization analyzer (SAICAS) at intervals 1 / 10 smaller than the period expected from the manufacturing method, and the collected samples are subjected to pyrolysis GC / MS analysis to obtain the peak value of the fragment derived from the binder. This is applied to a calibration curve obtained using binders of known concentration to quantify the binder concentration. The period is calculated by plotting the binder concentration in each sample. When excavating with SAICAS, the distance (film thickness) until it reaches the substrate is obtained and correlated with the previous period to determine area A. High The average thickness t High and area A Low The average thickness tLow Calculate.

[0060] [Figure 3] FIG. 3 is a schematic cross-sectional view showing an electrode according to another embodiment of the present invention. In this specification, region A High The average porosity in High " and Area A Low The average porosity in Low "The average porosity φ High and average porosity φ Low are the average porosity of each region in one period. Region A in the electrode of the present invention High Average porosity φ in High and area A Low Average porosity φ in Low It is preferable that the formula (2) is satisfied. φ High >φ Low ...Equation (2)

[0061] When the average porosity of each region in the electrode of the present invention satisfies formula (2), an electrode with excellent cycle characteristics and rate characteristics can be obtained. Furthermore, compared to an electrode that satisfies formula (1), the average thickness of the entire electrode mixture layer can be reduced, resulting in a superior electrode in terms of volumetric energy density. The mechanism behind this is unclear, but is presumed to be as follows. The expansion and contraction of the active material caused by the charge and discharge reaction occurs in region A where the binder concentration, which acts as a resistance component, is low. Low Since the stress and strain inside the electrode mixture layer progress from region A High Focus on Area A High The region A in the electrode of the present invention has a high binder concentration and is therefore relatively resistant to stress strain. High Average porosity φ in High and area A Low Average porosity φ in Low When formula (2) is satisfied, the buffer layer acts as a buffer to relieve stress strain, resulting in better cycle characteristics. The buffer layer also facilitates electrolyte penetration, resulting in better rate characteristics.

[0062] Region A in the electrode of the present invention High Average porosity φ in High and area A Low Average porosity φ in Low It is preferable that the temperature changes continuously from the viewpoint of preventing damage to the electrode mixture layer. In this specification, "area A High Average porosity φ in High and area A Low Average porosity φ in Low The phrase "continuously changes" means that the thickness of the electrode mixture layer 2 is changed in at least one direction perpendicular to the thickness direction of the electrode mixture layer 2. High From Area A Low This indicates that the average porosity changes gradually over the entire length of the active material layer. This is distinct from a case where the average porosity changes stepwise (discontinuously), such as when two active material layers with different average porosities are adjacent to each other. In other words, this indicates that there is no boundary, or interface, where the average porosity changes suddenly. The continuous change in average porosity in each region can be confirmed, for example, by observing the cross section of the electrode mixture layer using an SEM.

[0063] Average porosity φ Low Average porosity φ High The ratio (φ High / φ Low ) is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of preventing damage to the electrode mixture layer, it is preferably 1.5 or less, more preferably 0.13 or less. Also, from the viewpoint of efficiently relaxing stress strain, it is preferably 1.1 or more, more preferably 1.2 or less. The average porosity φ Low Average porosity φ High The ratio (φ High / φ Low ) are calculated using values ​​from the same period.

[0064] The method for measuring the average porosity of the electrode mixture layer is not particularly limited and can be appropriately selected depending on the purpose. Examples are shown below. The base resin for 53-type embedding epoxy resin (Lot No. 53512040149, Sankei Co., Ltd.) and the curing agent (Lot No. 53572040342, Sankei Co., Ltd.) were thoroughly mixed in a volume ratio of 1:2, and the electrode composite layer was embedded in the resin using a vacuum impregnation device (Buehler Vacuum Impregnation Equipment I, Sankei Co., Ltd.) and allowed to cure for 24 hours. The electrode composite layer embedded in the epoxy resin was processed using a cross-section polisher (JEOL Ltd.), and the cross section was observed using a tabletop scanning electron microscope (SEM / EDX) (Phenom Prox, Jasco International Inc.), and SEM photographs of the electrode composite layer were taken. The SEM photograph of the obtained electrode mixture layer was binarized (see Figure 4) using image processing software (Image-Pro Premier version 9.2 64-bit, manufactured by Hakuto Co., Ltd.) to determine the area of ​​the particle-derived regions and the area of ​​the void-derived regions. The void-derived region was then divided by the total area to calculate the porosity. Note that when binarizing using software, for example, regions in the binarized image with a density greater than 50% may be determined as particles or voids, and regions with a density of 50% or less may be determined as voids or particles.

[0065] The electrode mixture layer in the present invention preferably satisfies at least one of formula (1) and formula (2) from the viewpoint of improving cycle characteristics and rate characteristics.

[0066] [Figure 5] FIG. 5 is a schematic cross-sectional view showing an electrode according to another embodiment of the present invention. In this specification, the average thickness t High The area on the substrate side of the electrode mixture layer is defined as "area A" based on an imaginary line that divides the electrode mixture layer into two equal parts in a direction perpendicular to the thickness direction of the electrode mixture layer. High,Under The region of the electrode mixture layer that is not on the substrate side is called “region A High,surface "It is called " Area A High,Under Average binder concentration C High,Under and area A High,surface Average binder concentration C High,surface It is preferable that the formula (3) is satisfied. C High,Under <C High,surface ...Equation (3) The average binder concentration C High,Under and average binder concentration C High,surface are the average binder concentrations in each region in one cycle.

[0067] When the average binder concentration in each region of the electrode of the present invention satisfies formula (3), an electrode with excellent cycle characteristics can be obtained. The mechanism behind this is not clear, but is presumed to be as follows. The expansion and contraction of the active material caused by the charge and discharge reaction occurs in region A where the binder concentration, which acts as a resistance component, is low. Low Since the stress and strain inside the electrode mixture layer progress from region A High Focus on Area A in particular. High,surface is area A High,Under Unlike the above, since it is not bound to a substrate, it is more susceptible to the effects of expansion and contraction. Therefore, by satisfying formula (3), stronger film strength can be obtained, resulting in excellent cycle characteristics.

[0068] [Figures 6A to 6B] FIG. 6A is a schematic cross-sectional view showing an electrode according to another embodiment of the present invention. The electrode mixture layer 2 may have an opening 201 as shown in FIG. 6A. The number of openings 201 is preferably one or more, and more preferably two or more. The opening 201 may penetrate the electrode mixture layer from the surface of the electrode mixture layer to the surface of the substrate, or may not penetrate all the way to the surface of the substrate. Opening 201 may be hollow or filled with material 202. When opening 201 is filled with material 202, material 202 may be a single type or a mixture of two or more types, but in either case, the material is different from the material that constitutes the electrode mixture layer. Material 202 is preferably a material having a solid electrolyte from the viewpoint of improving ion conductivity. The electrode mixture layer having the openings 201 can be suitably produced by using inkjet as an electrode mixture layer forming means, since application control is easy.

[0069] FIG. 6B is a schematic cross-sectional view showing an electrode according to another embodiment of the present invention. As shown in FIG. 6B, the electrode mixture layer may include an adhesive layer 203 between the substrate 1 and the electrode mixture layer 2, the adhesive layer 203 containing a metal that alloys with lithium.

[0070] (Electrode manufacturing method and electrode manufacturing device) The electrode manufacturing method of the present invention is an electrode manufacturing method including an electrode mixture layer forming step, and the electrode mixture layer forming step includes an electrode mixture layer forming liquid composition applying step and an electrode mixture layer forming liquid composition drying step, and may include other steps as necessary. The electrode manufacturing apparatus according to the present invention is an electrode manufacturing apparatus including an electrode mixture layer forming means, and the electrode mixture layer forming means includes an electrode mixture layer forming liquid composition applying means and an electrode mixture layer forming liquid composition drying means, and may have other means as necessary. The electrode manufacturing method can be suitably carried out by an electrode manufacturing apparatus, the electrode mixture layer forming step can be suitably carried out by an electrode mixture layer forming means, the electrode mixture layer forming liquid composition applying step can be suitably carried out by an electrode mixture layer forming liquid composition applying means, the electrode mixture layer forming liquid composition drying step can be suitably carried out by an electrode mixture layer forming liquid composition drying means, and the other steps can be suitably carried out by other means. The electrode mixture layer obtained by the electrode mixture layer forming step has a binder concentration that varies periodically and continuously in at least one direction perpendicular to the thickness direction of the electrode mixture layer.

[0071] <Electrode mixture layer forming step and electrode mixture layer forming means> The electrode mixture layer forming step is a step of forming an electrode mixture layer on a substrate, and includes a step of applying an electrode mixture layer forming liquid composition and a step of drying the electrode mixture layer forming liquid composition. The electrode mixture layer forming means is a means for forming an electrode mixture layer on a substrate, and includes an electrode mixture layer forming liquid composition applying means and an electrode mixture layer forming liquid composition drying means.

[0072] <<Electrode mixture layer forming liquid composition applying step, electrode mixture layer forming liquid composition applying means>> The electrode mixture layer forming liquid composition applying step is a step of applying an electrode mixture layer forming liquid composition containing an active material, a binder, and a dispersion medium onto a substrate. The electrode mixture layer forming liquid composition applying means is a means for applying an electrode mixture layer forming liquid composition containing an active material, a binder, and a dispersion medium onto a substrate.

[0073] The means for applying the electrode mixture layer-forming liquid composition is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include liquid ejection methods such as inkjet method, spray coating method, and dispenser method, spin coating method, casting method, microgravure coating method, gravure coating method, bar coating method, roll coating method, wire bar coating method, dip coating method, slit coating method, capillary coating method, nozzle coating method, gravure printing method, screen printing method, flexographic printing method, offset printing method, and reverse printing method. Among these, liquid ejection methods are preferred, and inkjet methods are more preferred. When a liquid ejection method is used as a means for applying a liquid composition for forming an electrode composite layer, an electrode with a periodically and continuously varying binder concentration can be easily obtained. In particular, when an inkjet method is used, an electrode with a periodically and continuously varying binder concentration can be obtained in any pattern on the XY plane. Furthermore, because electrodes can be produced in any shape without contact, there is also the advantage of minimizing loss of active material due to die-cutting during the electrode production process.

[0074] <<<Liquid composition for forming electrode composite layer>>> The electrode mixture layer-forming liquid composition contains an active material, a binder, and a dispersion medium, and may contain a conductive aid, a dispersant, a solid electrolyte, and other components as required. The active material, binder, conductive additive, and solid electrolyte may be the same as those in the (electrodes) section, and therefore redundant descriptions will be omitted.

[0075] -Dispersion medium- The dispersion medium is not particularly limited and can be appropriately selected depending on the purpose. Examples include aqueous dispersion media such as water, ethylene glycol, and propylene glycol; amide-based dispersion media such as N-methyl-2-pyrrolidone, 2-pyrrolidone, and N,N-dimethylacetamide; ketone-based dispersion media such as cyclohexanone; ester-based dispersion media such as butyl acetate, butyl butyrate, isobutyl isobutyrate, methyl hexanoate, ethyl octanoate, and ethyl decanoate; aromatic dispersion media such as mesitylene; and alcohol-based dispersion media such as 2-n-butoxymethanol and 2-dimethylethanol. When a positive electrode active material is contained as the active material, an amide-based dispersion medium, an ester-based dispersion medium, or a ketone-based dispersion medium is preferred from the viewpoint of obtaining excellent dispersibility. When a sulfide solid electrolyte is contained as another component, an ester-based compound is preferred, and it is more preferred that the alkyl group is selected from a linear alkyl group and a branched alkyl group having 3 or more carbon atoms on the carbonyl group carbon side, and that the alkyl group on the oxygen side of the carbonyl group is a methyl group or an ethyl group. These may be used alone or in combination of two or more.

[0076] The binder contained in the electrode mixture layer-forming liquid composition preferably has a specific gravity smaller than that of the active material, from the viewpoint of changing the binder concentration in the electrode mixture layer. Specifically, the ratio of the specific gravity of the active material to the specific gravity of the binder is preferably 1.5 times or more, more preferably 2 times or more. The method for measuring the specific gravity is not particularly limited and can be appropriately selected depending on the purpose. For example, the specific gravity can be calculated by measuring the true density of the active material or binder by a pycnometer method in accordance with JIS K 7112 Method B and calculating the ratio to the true density of the solvent.

[0077] The binder contained in the liquid composition for forming an electrode mixture layer is preferably dissolved in the dispersion medium, from the viewpoint that the resulting electrode satisfies formula (3) and the cycle characteristics are improved.

[0078] The dispersion medium preferably has a boiling point under normal pressure conditions. The boiling point of the dispersion medium is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoints of storage stability and handleability, it is preferably 100° C. or higher, more preferably 120° C. or higher, and even more preferably 150° C. or higher. From the viewpoint of quick drying in the drying step, it is preferably 300° C. or lower, more preferably 250° C. or lower, and even more preferably 200° C. or lower.

[0079] When a positive electrode active material is used as the active material, the water content of the dispersion medium is preferably 2,000 ppm or less, and more preferably 1,000 ppm or less. When a sulfide solid electrolyte is contained as another component, the water content of the dispersion medium is preferably 100 ppm or less, and more preferably 50 ppm or less. The method for measuring the water content of the dispersion medium is not particularly limited and can be selected appropriately depending on the purpose, and can be, for example, measured by Karl Fischer water content measurement using coulometric titration with water vaporization at 25° C. The measuring device is not particularly limited and can be selected appropriately depending on the purpose, and examples thereof include a Karl Fischer trace water content analyzer (CA-200, manufactured by Nitto Seiko Analytech Co., Ltd.).

[0080] [viscosity] The viscosity of the liquid composition for forming an electrode mixture layer is not particularly limited and can be appropriately selected depending on the purpose. When measured at 25°C and a rotation speed of 100 rpm, the viscosity is preferably 20 mPa·s or more and 200 mPa·s or less, more preferably 30 mPa·s or more and 100 mPa·s or less, and even more preferably 40 mPa·s or more and 70 mPa·s or less. When the steady flow shear viscosity (25°C, 100 rpm) of the liquid composition for forming an electrode mixture layer is 20 mPa·s or more, uneven drying is less likely to occur during the drying process, making it easier to form an electrode with a periodic binder concentration. When the steady flow shear viscosity (25° C., 100 rpm) of the electrode mixture layer forming liquid composition is 200 mPa·s or less, the ejection properties from the liquid ejection head can be improved. The method for measuring the viscosity of the electrode mixture layer-forming liquid composition is not particularly limited and can be selected appropriately depending on the purpose, and can be measured, for example, in accordance with JIS Z 8803. The device used for measurement is not particularly limited and can be selected appropriately depending on the purpose, and examples include a TV25 viscometer (a cone-plate type viscometer manufactured by Toki Sangyo Co., Ltd.).

[0081] [Solid content concentration] The solid content concentration of the liquid composition for forming an electrode mixture layer is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. When the solids concentration of the electrode mixture layer-forming liquid composition is 40% by mass or more, thixotropy is easily exhibited, resulting in good dispersion stability, and flow is suppressed during the drying process of the applied electrode mixture layer-forming liquid composition, thereby suppressing film thickness and composition variations due to drying, making it easier to obtain an electrode with the desired periodic binder concentration.In addition, the required drying time is shortened, resulting in improved productivity, reduced environmental impact, and associated cost savings.

[0082] In this specification, the "solids concentration of the electrode mixture layer forming liquid composition" refers to the mass percentage of the mass of the components contained therein, excluding the dispersion medium and water, relative to the total mass of the electrode mixture layer forming liquid composition. The method for measuring the solids concentration of the liquid composition for forming an electrode mixture layer is not particularly limited and can be appropriately selected depending on the purpose. For example, when the composition of the liquid composition for forming an electrode mixture layer is known, the solids concentration can be determined using the following formula (4); when the composition of the liquid composition for forming an electrode mixture layer is unknown, the solids concentration can be measured in accordance with JIS K5601-1-2. Solid concentration = {total solids (parts by mass) / (total solids (parts by mass) + dispersion medium (parts by mass) + water (parts by mass))} × 100 (%) (Formula 4) The device used to measure the solids concentration of the liquid composition for forming an electrode mixture layer is not particularly limited and can be selected appropriately depending on the purpose, and examples include a heat-drying type solids meter (MX-50, manufactured by A&D Co., Ltd.).

[0083] [Method of manufacturing liquid composition for forming electrode mixture layer] The electrode mixture layer-forming liquid composition can be produced by dissolving or dispersing each component in a dispersion medium. Specifically, the electrode mixture layer-forming liquid composition can be produced by mixing each component with a dispersion medium using a mixer such as a ball mill, a sand mill, a bead mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, a planetary mixer, or a Filmix.

[0084] In the electrode mixture layer-forming liquid composition application step, the cycle for applying the electrode mixture layer-forming liquid composition to the substrate is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of suppressing the detachment of the active material from the resulting electrode mixture layer and the growth of Li dendrites and thereby obtaining excellent cycle characteristics, the cycle thickness is preferably 0.2 mm or more and 2.5 mm or less. Furthermore, from the viewpoint of efficiently binding the active material, the cycle thickness is preferably 0.4 mm or more, more preferably 0.6 mm or more, and is preferably 1.7 mm or less, and more preferably 1.3 mm or less. If the period in the electrode mixture layer forming liquid composition application step is 0.2 mm or more, the binding properties will not change compared to an electrode with a uniform binder concentration, and problems such as inability to obtain advantageous cycle characteristics can be resolved. If the cycle in the electrode mixture layer forming liquid composition application step is 2.5 mm or less, it is possible to overcome the problem that the active material cannot be sufficiently bound in regions where the binder concentration is low.

[0085] <<Liquid composition drying step for electrode composite layer formation, means for drying liquid composition for electrode composite layer formation>> The electrode mixture layer forming liquid composition drying step is a step of drying the applied electrode mixture layer forming liquid composition. The electrode mixture layer forming liquid composition drying means is a means for drying the applied electrode mixture layer forming liquid composition.

[0086] The means for drying the electrode mixture layer-forming liquid composition is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include an IR heater and a hot air heater.

[0087] In the electrode mixture layer-forming liquid composition drying step, it is preferable to dry the electrode mixture layer-forming liquid composition applied to the substrate before it is flattened, from the viewpoint that the resulting electrode satisfies formula (1) and has improved rate characteristics and cycle characteristics. In this specification, "flattened" refers to a state in which the electrode mixture layer forming liquid composition applied as droplets coalesces with adjacent droplets, resulting in a uniform film thickness.

[0088] The drying temperature in the electrode mixture layer forming liquid composition drying step is not particularly limited and can be appropriately selected depending on the purpose. 3 Pa or more 10 5 It is preferable to set the temperature so that the RH is equal to or lower than 100 Pa. The vapor pressure of the solvent for forming the electrode mixture layer is 10 3 By setting the temperature at which the tensile strength is 100 kJ / cm 3 or more, the time required for drying is shortened, productivity is improved, and the occurrence of compositional unevenness can be suppressed. The vapor pressure of the solvent for forming the electrode mixture layer is 10 5By setting the temperature at which the temperature is 100 Pa or less, it is possible to eliminate the problem of bubbles being generated inside the electrode mixture layer forming liquid composition applied to the substrate, which causes pinholes. When the solvent for forming the electrode mixture layer is a mixed solvent consisting of two or more solvents, the vapor pressure of the mixed solvent can be calculated based on Raoult's law. The vapor pressure measurement method is not particularly limited and can be selected appropriately depending on the purpose, and examples include the static method, boiling point method, isoteniscope method, substrate flow method, and DSC method. It can also be calculated based on the Antoine equation.

[0089] <<Other processes and other means>> The other steps are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a waiting step and a pressing step. The other means are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include pressing means.

[0090] The waiting step is a step of waiting for a certain period of time after the electrode mixture layer forming liquid composition applying step and before the electrode mixture layer forming liquid composition drying step. The waiting step allows the active material in the applied electrode mixture layer forming liquid composition to settle sufficiently, which makes it easier for the resulting electrode to satisfy formula (3) and improves the cycle characteristics. The "certain time" in the waiting step is not particularly limited and can be selected appropriately depending on the purpose, as long as it is a time that does not cause the applied liquid composition for forming an electrode mixture layer to become flattened, and can be, for example, 1 second or more and 300 seconds or less.

[0091] The pressing step is a step of pressing the electrode obtained after the electrode mixture layer forming liquid composition drying step. The pressing means is a means for pressing the obtained electrode. By undergoing the pressing step, the resulting electrode is more likely to satisfy formula (2), and the volumetric energy, rate characteristics, and cycle characteristics are improved. The pressing means is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include uniaxial pressing, isostatic pressing, roll pressing, etc. Among these, roll pressing is preferred from the viewpoint of productivity. The conditions for pressing are not particularly limited and can be selected appropriately depending on the purpose. It is preferable to adjust the pressing pressure and gap so that the volume density of the electrode mixture layer falls within a range that satisfies the desired battery design.

[0092] In the case of the positive electrode mixture layer, from the viewpoint of reducing the electronic resistance in the electrode mixture layer, the volume density is set to 2.0 g / cm 3 It is preferable that the concentration is 2.5 g / cm or more. 3 More preferably, it is 3.0 g / cm or more. 3 From the viewpoint of ensuring a porosity that allows the electrolyte to permeate, it is more preferable that the porosity is 4.0 g / cm. 3 It is preferable that the concentration is 3.5 g / cm or less. 3 More preferably, it is: For example, a coating weight of 20 mg / cm2 on a substrate with an average thickness of 15 μm 2 The positive electrode mixture layer has a volume density of 3.0 g / cm 3 In this case, 67 μm (≒ 20 mg / cm 2 ×3.0g / cm 3 ) That is, the roll press gap should be set to 82 μm, which corresponds to the thickness of the substrate, and a load of, for example, 7 tons should be applied as a pressing pressure sufficient to crush the electrode mixture layer.

[0093] In the case of the negative electrode mixture layer, from the viewpoint of reducing the electronic resistance in the negative electrode mixture layer, the volume density is set to 1.0 g / cm 3 It is preferable that the concentration is 1.5 g / cm or more. 3 From the viewpoint of ensuring a porosity that allows the electrolyte to permeate, it is more preferable that the porosity is 3.0 g / cm or more. 3 It is preferable that:

[0094] Here, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In each drawing, the same components are denoted by the same reference numerals, and redundant explanations may be omitted. Furthermore, the number, position, shape, etc. of the components are not limited to the present embodiment, and the number, position, shape, etc. may be any number, position, shape, etc. that is preferable for implementing the present invention.

[0095] [FIG. 7: An embodiment in which an electrode mixture layer is formed by directly applying an electrode mixture layer-forming liquid composition to a substrate] FIG. 7 is a schematic diagram showing an electrode manufacturing apparatus according to one embodiment of the present invention. The electrode manufacturing apparatus 500 is an apparatus for manufacturing an electrode mixture layer using an electrode mixture layer-forming liquid composition. The electrode manufacturing apparatus 500 includes a printing unit 100 that applies an electrode mixture layer-forming liquid composition 37 onto a printing substrate 34 to form an electrode mixture layer-forming liquid composition layer, and, if necessary, a heating unit 200. The electrode manufacturing apparatus 500 also includes a transport unit 35 that transports the printing substrate 34, and the transport unit 35 transports the printing substrate 34 at a preset speed through the printing unit 100 and, if necessary, the heating unit 200 in that order.

[0096] -Printing Department 100- The printing unit 100 includes a printing device 31a, which is an example of an electrode composite layer forming liquid composition applying means that applies an electrode composite layer forming liquid composition 37 to form an electrode composite layer on the printing substrate 34, a storage container 31b that stores the electrode composite layer forming liquid composition 37, and a supply tube 31c that supplies the electrode composite layer forming liquid composition 37 stored in the storage container 31b to the printing device 31a. Storage container 31b stores electrode mixture layer forming liquid composition 37, and printing unit 100 ejects electrode mixture layer forming liquid composition 37 from printing device 31a to form a thin film of electrode mixture layer forming liquid composition layer on printing substrate 34. Storage container 31b may be integrated with the electrode manufacturing apparatus, or may be detachable from the electrode manufacturing apparatus. Alternatively, it may be a container used for adding to a storage container integrated with the electrode manufacturing apparatus or a storage container detachable from the electrode manufacturing apparatus. The storage container 31b and the supply tube 31c can be arbitrarily selected as long as they can stably store and supply the electrode mixture layer forming liquid composition 37.

[0097] -Heating section 200- 7, the heating unit 200 has a heating device 33a, and performs an electrode mixture layer forming liquid composition drying step in which the electrode mixture layer forming liquid composition layer formed by the printing unit 100 is heated by the heating device 33a to dry the remaining liquid. This allows the electrode mixture layer to be formed. The heating unit 200 may remove the liquid under reduced pressure. The heating device 33a is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include an IR heater and a hot air heater. The heating temperature and time can be appropriately selected depending on the boiling point of the liquid contained in the electrode mixture layer-forming liquid composition layer and the thickness of the formed film.

[0098] [Figure 8] FIG. 8 is a schematic diagram showing an electrode manufacturing apparatus according to another embodiment of the present invention. Liquid ejection device 300 ′ can circulate the electrode mixture layer forming liquid composition through liquid ejection head 306 , tank 307 , and tube 308 by controlling pump 310 , valve 311 , and valve 312 . In addition, the liquid ejection device 300′ is provided with an external tank 313, and when the liquid composition for forming an electrode composite layer in the tank 307 decreases, it is possible to supply the liquid composition for forming an electrode composite layer from the external tank 313 to the tank 307 by controlling the pump 310, the valve 311, the valve 312, and the valve 314. By using such an electrode manufacturing device, it is possible to eject the electrode mixture layer forming liquid composition onto a targeted location on a substrate.

[0099] [Figure 9] FIG. 9 is a schematic diagram showing an electrode manufacturing apparatus according to another embodiment of the present invention. The method for manufacturing an electrode includes a step of sequentially discharging electrode mixture layer forming liquid composition 12A onto substrate 211 using a liquid discharge device. First, an elongated substrate 211 is prepared. Then, the substrate 211 is wound around a cylindrical core and set on a feed roller 304 and a take-up roller 305 so that the side on which the electrode mixture layer is to be formed faces upward in FIG. 9. Here, the feed roller 304 and the take-up roller 305 rotate counterclockwise in FIG. 9, and the substrate 211 is transported from right to left in FIG. 9. Then, droplets of the electrode mixture layer-forming liquid composition 12A are ejected from a liquid ejection head 306 installed above the substrate 211 between the feed roller 304 and the take-up roller 305 onto the substrates 211 that are being transported sequentially, in the same manner as in FIG. 7. A plurality of liquid ejection heads 306 may be installed in a direction substantially parallel to or substantially perpendicular to the transport direction of the substrate 211. Next, the substrate 211 onto which the droplets of the electrode mixture layer forming liquid composition 12A have been ejected is transported to a heating unit 309 by a delivery roller 304 and a take-up roller 305. As a result, an electrode mixture layer 212 is formed, and an electrode 210 having the electrode mixture layer 212 provided on the substrate 211 is obtained.

[0100] [Figure 10] FIG. 10 is a schematic diagram showing a modified example of an electrode manufacturing apparatus according to one embodiment of the present invention. 10, liquid ejection apparatus 300A' and liquid ejection apparatus 300B' may be used in combination. That is, the electrode mixture layer forming liquid composition may be supplied from external tanks 313A and 313B connected to tanks 307A and 307B, and the liquid ejection head may have multiple heads 306A and 306B. Accordingly, tubes 308A and 308B, valves 311A, 311B, 312A, 312B, valves 314A and 314B, and pumps 310A and 310B may be provided.

[0101] [FIG. 11: An embodiment in which an electrode mixture layer is formed by indirectly applying an electrode mixture layer-forming liquid composition to a substrate] 11 is a block diagram (part 1) showing an example of a printing unit employing an inkjet system and a transfer system as a means for applying a liquid composition for forming an electrode composite layer in an electrode manufacturing apparatus according to one embodiment of the present invention. The printing unit in FIG. 11 uses a drum-shaped intermediate transfer member. Printing unit 400' is an inkjet printer that transfers an electrode mixture layer forming liquid composition onto a substrate via intermediate transfer body 4001, thereby forming an electrode mixture layer on the substrate. The printing section 400 ′ includes an inkjet section 420 , a transfer drum 4000 , a pre-treatment unit 4002 , an absorption unit 4003 , a heating unit 4004 , and a cleaning unit 4005 .

[0102] The inkjet unit 420 includes a head module 422 that holds a plurality of heads 101 . The head 101 ejects the liquid composition for forming an electrode mixture layer onto the intermediate transfer body 4001 supported by the transfer drum 4000, thereby forming a film of the liquid composition for forming an electrode mixture layer on the intermediate transfer body 4001. Each head 101 is a line head, and nozzles are arranged over a range that covers the width of the recording area of ​​a substrate of the largest usable size. The head 101 has a nozzle surface on its underside on which nozzles are formed, and the nozzle surface faces the surface of the intermediate transfer body 4001 via a minute gap. In this embodiment, the intermediate transfer body 4001 is configured to move cyclically on a circular orbit, so the multiple heads 101 are arranged radially.

[0103] Transfer drum 4000 faces impression cylinder 621 and forms a transfer nip. Pretreatment unit 4002 applies, for example, a reaction liquid onto intermediate transfer body 4001 to increase the viscosity of the electrode mixture layer forming liquid composition before head 101 ejects the electrode mixture layer forming liquid composition.

[0104] The absorbing unit 4003 absorbs liquid components from the liquid composition for forming an electrode mixture layer on the intermediate transfer body 4001 before transfer.

[0105] The heating unit 4004 heats the electrode mixture layer forming liquid composition on the intermediate transfer body 4001 before transfer. By heating the electrode mixture layer forming liquid composition, an electrode mixture layer is formed. In addition, the solvent is removed, improving transferability to the substrate.

[0106] A cleaning unit 4005 cleans the surface of the intermediate transfer body 4001 after transfer, and removes foreign matter such as ink and dust remaining on the intermediate transfer body 4001 .

[0107] The outer peripheral surface of the impression cylinder 621 is in pressure contact with the intermediate transfer body 4001, and the electrode mixture layer on the intermediate transfer body 4001 is transferred to the substrate when the substrate passes through the transfer nip between the impression cylinder 621 and the intermediate transfer body 4001. The impression cylinder 621 may be configured to have at least one gripping mechanism on its outer peripheral surface that holds the leading end of the substrate.

[0108] [Figure 12] 12 is a block diagram (part 2) showing an example of a printing unit employing an inkjet system and a transfer system as a means for applying a liquid composition for forming an electrode composite layer in an electrode manufacturing apparatus according to one embodiment of the present invention. The printing unit in FIG. 12 uses an intermediate transfer body in the form of an endless belt. The printing unit 400 ″ is an inkjet printer that transfers the electrode mixture layer forming liquid composition onto a substrate via an intermediate transfer belt 4006 to form an electrode mixture layer. The printing section 400'' includes an inkjet section 420, a transfer roller 622, an intermediate transfer belt 4006, a heating unit 4007, a cleaning roller 4008, a drive roller 4009a, an opposing roller 4009b, a shape maintaining roller 4009c, a shape maintaining roller 4009d, a shape maintaining roller 4009e, and a shape maintaining roller 4009f.

[0109] The printing unit 400'' ejects droplets of a liquid composition for forming an electrode mixture layer onto the outer peripheral surface of the intermediate transfer belt 4006 from a plurality of heads 101 provided in the inkjet unit 420. The liquid composition for forming an electrode mixture layer on the intermediate transfer belt 4006 is heated by a heating unit 4007 and thermally polymerized to form an electrode mixture layer. In the transfer nip portion where the intermediate transfer belt 4006 faces the transfer roller 622, the electrode mixture layer on the intermediate transfer belt 4006 is transferred to the substrate. After transfer, the surface of the intermediate transfer belt 4006 is cleaned by a cleaning roller 4008.

[0110] The intermediate transfer belt 4006 is stretched over a drive roller 4009a, an opposing roller 4009b, multiple shape maintaining rollers 4009c, 4009d, 4009e, 4009f, and multiple support rollers 4009g, and moves in the direction of the arrow in Fig. 12. The support roller 4009g, which is provided opposite the head 101, maintains the tension state of the intermediate transfer belt 4006 when ink droplets are ejected from the head 101.

[0111] [Figures 13 to 16] Fig. 13 is a schematic diagram showing an example of a formation pattern of an electrode mixture layer in a manufacturing method of an electrode according to one embodiment of the present invention, and Figs. 14 to 16 are schematic diagrams showing other examples of a formation pattern of an electrode mixture layer in a manufacturing method of an electrode according to one embodiment of the present invention. 13 to 16, the X direction is the direction perpendicular to the printing direction and parallel to the substrate surface, and the Y direction is the printing direction. By patterning the electrode mixture layer in this way, the surface area is increased. FIG. 13 shows a region 13 (region A) with a high binder concentration in the X direction. High ) and low binder concentration region 14 (region A Low ) are periodically formed and are flat in the Y direction. FIG. 14 shows a region 15 (region A) with a high binder concentration in the Y direction. High ) and low binder concentration region 16 (region A Low ) are periodically formed and are flat in the X direction. FIG. 15 shows a region 17 (region A) with a high binder concentration in the X direction. High ) and low binder concentration region 18 (region A Low ) are periodically formed, and a region 17 (region A) with a high binder concentration is also formed in the Y direction. High ) and low binder concentration region 18 (region A Low ) is an electrode mixture layer in which the electrodes are periodically formed. At this time, compared to the configurations shown in FIGS. 13 and 14, a region with a high binder concentration along the X direction and the Y direction (region A High ) and the low binder concentration region (region A Low ) are periodically formed in a lattice structure, the active material can be further prevented from falling off, and the performance of the electrochemical device can be improved.

[0112] 16(a) and (b) show the region 17 (region A) with a high binder concentration in the X direction as shown in FIG. High ) and low binder concentration region 18 (region A Low ) are periodically formed, and a region with a high binder concentration in the Y direction (region A High) and low binder concentration region 18 (region A Low ) are periodically formed in the electrode mixture layer, and the binder concentration region 17 (region A High ) and low binder concentration region 18 (region A Low ) is a dot-shaped (approximately circular) electrode mixture layer. 16(a) is a plan view, and FIG. 16(b) is a side view. Such a dot pattern can further suppress the active material from falling off, thereby further improving the performance of the electrochemical device.

[0113] (electrochemical element) The electrochemical device according to the present invention has the electrode of the present invention and may further have other components as necessary. In other words, the electrochemical device according to the present invention may have a positive electrode, a negative electrode, an electrolyte, a separator having the electrolyte disposed between the positive electrode and the negative electrode, and an exterior. When a solid electrolyte or a gel electrolyte is used, a separator is not necessary.

[0114] <Electrolytes> The electrolyte may be an aqueous electrolyte solution or a non-aqueous electrolyte solution.

[0115] -Aqueous electrolyte solution- The electrolyte aqueous solution is an aqueous solution in which an electrolyte salt is dissolved in water. The electrolyte salt in the aqueous electrolyte solution is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include sodium hydroxide, potassium hydroxide, sodium chloride, potassium chloride, ammonium chloride, zinc chloride, zinc acetate, zinc bromide, zinc iodide, zinc tartrate, and zinc perchlorate.

[0116] -Non-aqueous electrolyte- As the non-aqueous electrolyte, a non-aqueous electrolytic solution, a solid electrolyte, or a gel electrolyte can be used.

[0117] --Nonaqueous electrolyte-- The non-aqueous electrolyte is an electrolyte in which an electrolyte salt is dissolved in a non-aqueous solvent. The non-aqueous solvent is not particularly limited and can be appropriately selected depending on the purpose. For example, it is preferable to use an aprotic organic solvent. As the aprotic organic solvent, carbonate-based organic solvents such as chain carbonates and cyclic carbonates can be used. Among these, chain carbonates are preferred because of their high dissolving power for electrolyte salts. In addition, it is preferable that the aprotic organic solvent has low viscosity.

[0118] Examples of the chain carbonate include dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC).

[0119] The content of the chain carbonate in the non-aqueous solvent is preferably 50% by mass or more. When the content of the chain carbonate in the non-aqueous solvent is 50% by mass or more, the content of the cyclic substance is reduced even when a cyclic substance (e.g., a cyclic carbonate or a cyclic ester) having a high dielectric constant in a non-aqueous solvent other than the chain carbonate is used. Therefore, even when a non-aqueous electrolyte solution with a high concentration of 2M or more is prepared, the viscosity of the non-aqueous electrolyte solution is reduced, resulting in good penetration of the non-aqueous electrolyte solution into the electrodes and good ion diffusion.

[0120] Examples of cyclic carbonates include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), and vinylene carbonate (VC).

[0121] Examples of non-aqueous solvents that can be used other than carbonate-based organic solvents include ester-based organic solvents such as cyclic esters and chain esters; and ether-based organic solvents such as cyclic ethers and chain ethers.

[0122] Examples of cyclic esters include γ-butyrolactone (γBL), 2-methyl-γ-butyrolactone, acetyl-γ-butyrolactone, and γ-valerolactone.

[0123] Examples of chain esters include alkyl propionates, dialkyl malonates, alkyl acetates (e.g., methyl acetate (MA), ethyl acetate), and alkyl formates (e.g., methyl formate (MF), ethyl formate).

[0124] Examples of cyclic ethers include tetrahydrofuran, alkyltetrahydrofuran, alkoxytetrahydrofuran, dialkoxytetrahydrofuran, 1,3-dioxolane, alkyl-1,3-dioxolane, and 1,4-dioxolane.

[0125] Examples of the chain ether include 1,2-dimethoxyethane (DME), diethyl ether, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether, triethylene glycol dialkyl ether, and tetraethylene glycol dialkyl ether.

[0126] The electrolyte salt in the non-aqueous electrolyte solution is not particularly limited as long as it has high ionic conductivity and is soluble in the non-aqueous solvent. The electrolyte salt in the non-aqueous electrolyte preferably contains a halogen atom. Examples of cations constituting the electrolyte salt include lithium ions. Examples of anions that constitute the electrolyte salt include BF4 - , PF6 - , AsF6 - , CF3SO3 - , (CF3SO2)2N - , (C2F5SO2)2N - Examples include: The lithium salt is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include lithium hexafluorophosphate (LiPF), lithium borofluoride (LiBF), lithium arsenic hexafluoride (LiAsF), lithium trifluoromethasulfonate (LiCFSO), lithium bis(trifluoromethylsulfonyl)imide (LiN(CSO)), lithium bis(pentafluoroethylsulfonyl)imide (LiN(CSO)), etc. Among these, LiPF is preferred from the viewpoint of ionic conductivity, and LiBF is preferred from the viewpoint of stability. The electrolyte salt in the non-aqueous electrolyte solution may be used alone or in combination of two or more kinds.

[0127] The concentration of the electrolyte salt in the non-aqueous electrolytic solution is not particularly limited and can be appropriately selected depending on the purpose. However, when the non-aqueous electrochemical device is of a swing type, the concentration is preferably 1 mol / L to 2 mol / L, and when the non-aqueous electrochemical device is of a reserve type, the concentration is preferably 2 mol / L to 4 mol / L.

[0128] --Solid electrolyte-- As the solid electrolyte, the same as those described in the section <<<Solid Electrolyte>>> can be used.

[0129] --Gel electrolyte-- The gel electrolyte is not particularly limited as long as it exhibits ion conductivity and can be appropriately selected depending on the purpose. For example, polymers that form the network structure of the gel electrolyte include polyethylene oxide, polypropylene oxide, polyacrylonitrile, polymethyl methacrylate, polyvinyl chloride, copolymers of vinylidene fluoride and propylene hexafluoride, and polyethylene carbonate. The solvent molecules held in the gel electrolyte are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include ionic liquids. Examples of ionic liquids include 1-methyl-1-propylpyrrolidinium bis(fluorosulfonylimide), 1-butyl-1-methylpyrrolidinium bis(fluorosulfonylimide), 1-methyl-1-propylpiperidinium bis(fluorosulfonylimide), 1-ethyl-3-methylimidazolium bis(fluorosulfonylimide), 1-methyl-3-propylimidazolium bis(fluorosulfonylimide), and N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(fluorosulfonyl)imide. Alternatively, a mixture of a liquid such as tetraglyme, propylene carbonate, fluoroethylene carbonate, ethylene carbonate, or diethyl carbonate with a lithium salt may be used. These gel electrolytes may be used alone or in combination of two or more.

[0130] The electrolyte material to be dissolved or dispersed in a liquid to form a gel electrolyte may be a solution in which a polymer compound and an ionic liquid or a lithium salt are dissolved, or a solution in which a gel electrolyte precursor material, such as polyethylene oxide or polypropylene oxide having acrylate groups at both ends, and an ionic liquid or a lithium salt are dissolved may be used in combination.

[0131] <Separator> A separator is provided between the negative electrode and the positive electrode as needed to prevent short-circuiting between the negative electrode and the positive electrode. Examples of separators include paper such as kraft paper, vinylon-mixed paper, and synthetic pulp-mixed paper; polyolefin nonwoven fabrics such as cellophane, polyethylene graft membranes, and polypropylene melt-blown nonwoven fabrics; polyamide nonwoven fabrics, glass fiber nonwoven fabrics, and micropore membranes. The size of the separator is not particularly limited as long as it can be used in an electrochemical element. The separator may have a single layer structure or a laminated structure. When an aqueous electrolyte solution or a non-aqueous electrolyte solution is used as the electrolyte, a separator is necessary, but when a solid electrolyte or a gel electrolyte is used, a separator is not necessary.

[0132] <Exterior> The exterior packaging is not particularly limited as long as it can seal the electrodes, the electrolyte, and the separator or the solid electrolyte or the gel electrolyte, and any known exterior packaging can be appropriately selected depending on the purpose.

[0133] The shape of the electrochemical element is not particularly limited, and examples thereof include a laminate type, a cylindrical type in which a sheet electrode and a separator are spirally wound, a cylindrical type with an inside-out structure in which a pellet electrode and a separator are combined, and a coin type in which a pellet electrode and a separator are stacked.

[0134] Here, an embodiment of an electrochemical device according to the present invention will be described with reference to the drawings, although the present invention is not limited to these embodiments.

[0135] [Figure 17] FIG. 17 is a schematic cross-sectional view showing an electrochemical device according to one embodiment of the present invention. In the electrode element 40, the negative electrode 15 and the positive electrode 25 are stacked with a separator 30B interposed therebetween. Here, the positive electrode 25 is stacked on both sides of the negative electrode 15. A lead wire 41 is connected to the negative electrode substrate 11B, and a lead wire 42 is connected to the positive electrode substrate 21. In the case of a solid electrochemical element, the separator 30B may be replaced with a solid electrolyte or a gel electrolyte. Negative electrode 15 has negative electrode composite material layers 12B formed on both sides of negative electrode substrate 11B. The positive electrode 25 has a positive electrode substrate 21 and a positive electrode mixture layer 22 formed on both sides of the substrate 21 . The number of stacked negative electrodes 15 and positive electrodes 25 in the electrode element 40 is not particularly limited and can be appropriately selected depending on the purpose. The number of negative electrodes 15 and the number of positive electrodes 25 in the electrode element 40 may be the same or different.

[0136] [Figure 18] FIG. 18 is a schematic cross-sectional view showing an electrochemical device according to another embodiment of the present invention. The electrode element 40 has a configuration similar to that shown in Fig. 17. When the electrochemical element is a liquid-based electrochemical element, an electrolyte aqueous solution or a non-aqueous electrolyte is injected into the electrode element 40 to form an electrolyte layer 51, which is then sealed with an exterior casing 52. In the electrochemical element, the lead wires 41 and 42 are drawn out of the exterior casing 52. When the electrochemical element is a solid-state electrochemical element, the separator 30 may be replaced with a solid electrolyte or a gel electrolyte.

[0137] (Electrochemical element manufacturing apparatus and electrochemical element manufacturing method) The electrochemical element manufacturing apparatus according to the present invention comprises an electrode manufacturing means for manufacturing an electrode using the electrode manufacturing apparatus of the present invention, and an element manufacturing means for manufacturing an electrochemical element using the electrode, and further comprises other means as necessary. The method for manufacturing an electrochemical element according to the present invention includes an electrode manufacturing step of manufacturing an electrode using the electrode manufacturing apparatus of the present invention, and an element fabrication step of manufacturing an electrochemical element using the electrode, and may further include other steps as necessary.

[0138] <Electrode manufacturing means, electrode manufacturing process> The electrode manufacturing means has a storage container and an electrode mixture layer forming liquid composition applying means for applying the electrode mixture layer forming liquid composition stored in the storage container onto a substrate, and further has other means as necessary. The electrode production process includes a step of applying a liquid composition for forming an electrode mixture layer, and further includes other steps as necessary. The container, the electrode mixture layer forming liquid composition applying means, and the electrode mixture layer forming liquid composition applying step can be appropriately selected from the items explained in (Electrode manufacturing method and electrode manufacturing apparatus).

[0139] <Device Fabrication Means and Device Fabrication Process> The device fabrication means is a means for producing an electrochemical device using the electrodes. The device fabrication step is a step of manufacturing an electrochemical device using the electrodes. The method for producing an electrochemical element using electrodes is not particularly limited, and a known method for producing an electrochemical element can be appropriately selected depending on the purpose. For example, an electrochemical element can be produced by at least one of providing a counter electrode, winding or stacking, and housing in a container. The element forming step does not necessarily include the entire process of forming an element, but may include only a part of the process of forming an element, for example, a step of forming an electrode element.

[0140] [Uses of electrochemical elements] The electrochemical device can be suitably used as a secondary battery. The uses of electrochemical elements are not particularly limited, and examples thereof include notebook computers, pen-input computers, mobile computers, electronic book players, mobile phones, mobile fax machines, mobile copiers, mobile printers, headphone stereos, video movie machines, liquid crystal televisions, handheld vacuum cleaners, portable CDs, minidiscs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, lighting equipment, toys, game devices, clocks, strobe lights, cameras, and vehicles.

[0141] [Figure 19] FIG. 19 is a schematic diagram showing a mobile body that is an electrochemical device according to one embodiment of the present invention. The moving object 50 is, for example, an electric vehicle. The moving object 50 includes a motor 51, an electrochemical device 52, and wheels 53.

[0142] The electrochemical element 52 is an electrochemical element according to the present invention. The electrochemical element 52 supplies power to the motor 51 to drive the motor 51. The driven motor 51 can drive the wheels 53, and as a result, the mobile object 50 can move. Since the moving body 50 is equipped with an electrochemical element 52, short circuits between the positive and negative electrodes are prevented, and the moving body can be driven by power from the electrochemical element, which has excellent battery characteristics, allowing it to move safely and efficiently.

[0143] The mobile object 50 is not limited to an electric vehicle, but may also be a PHEV, HEV, or a locomotive or motorcycle that can run using a diesel engine and an electrochemical device in combination. The mobile object 50 may also be a transport robot used in a factory or the like that can run using only an electrochemical device or a combination of an engine and an electrochemical device. The mobile object 50 may also be an object that does not move as a whole, but only a part of it, such as an assembly robot that is arranged on a factory production line and that can operate an arm or the like using only an electrochemical device or a combination of an engine and an electrochemical device. [Example]

[0144] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples and comparative examples, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0145] Example 1 <Preparation of Liquid Composition for Forming Negative Electrode Mixture Layer> Solid components (active material, binder, conductive additive, dispersant) were mixed in a dispersion medium with the compositions and amounts shown in Table 1, and dispersed using a planetary centrifugal stirrer (Mazerustar, manufactured by Kurabo Industries, Ltd.), to obtain a liquid composition for forming a negative electrode composite layer (liquid composition for forming an electrode composite layer). The details of each component are as follows: Gr: Artificial graphite (manufactured by Aldrich, D50 = 5 μm) SiO: silicon oxide (manufactured by Aldrich, D50 = 8 μm) SBR: Styrene-butadiene rubber (manufactured by Aldrich) AB: Acetylene black (Denka Black, manufactured by Denka Co., Ltd.) CMC: Sodium carboxymethylcellulose (Aldrich)

[0146] <Preparation of negative electrode> The valve-type nozzle disclosed in Japanese Patent No. 7271956 was attached to an inkjet discharge evaluation device (device name: EV2500, manufactured by Ricoh Co., Ltd.), and the liquid composition for forming a negative electrode composite layer was applied to a copper foil current collector with an average thickness of 15 μm. The nozzle spacing (period T) was 2.54 mm. When the applied liquid composition for forming an electrode composite layer leveled and coalesced with adjacent droplets and the haze on the liquid surface was no longer visible to the naked eye, the composition was heated and dried at 80°C to obtain a negative electrode.

[0147] Examples 2 to 17 As shown in Tables 1 to 4, a liquid composition for forming a negative electrode composite layer and a negative electrode were prepared in the same manner as in Example 1, except that the composition of the liquid composition for forming a negative electrode composite layer, whether or not pressing was performed, and / or the period T were changed. The details of each component are as follows: Urethane binder (manufactured by Sanyo Chemical Co., Ltd.)

[0148] Example 18 Solid components (active material, binder, conductive additive, dispersant) were mixed in a dispersion medium with the compositions and amounts shown in Tables 1 to 4, and dispersed using a planetary centrifugal stirrer (Mazerustar, manufactured by Kurabo Industries, Ltd.), to obtain a liquid composition for forming a positive electrode composite layer (liquid composition for forming an electrode composite layer). The details of each component are as follows: NCM: Lithium nickel cobalt manganese oxide (average primary particle size 3.5 μm, manufactured by Toshima Manufacturing Co., Ltd.) P(DEAmEMA-BMA): Poly(diethylaminoethyl methacrylate-butyl methacrylate) copolymer PBMA: Polybutyl methacrylate (manufactured by Aldrich) BYK-ET3000 (BYK) NMP: N-methyl-2-pyrrolidone (Tokyo Chemical Industry Co., Ltd.)

[0149] The P(DEAmEMA-BMA):poly(diethylaminoethyl methacrylate-butyl methacrylate) copolymer was synthesized as follows. Under a nitrogen stream, degassed toluene was added to a flask and heated to 80°C. A mixed solution consisting of 33 mL of toluene, 25.00 g (175.8 mmol) of butyl methacrylate, 8.14 g (43.95 mmol) of 2-(diethylamino)ethyl methacrylate, and 109 mg (0.440 mmol) of 2,2'-azobis(2,4-dimethylvaleronitrile) was added dropwise over 1 hour with stirring. After completion of the addition, the mixture was stirred at 80°C for 8 hours, allowed to cool to room temperature, and then the reaction solution was added dropwise to methanol, and the precipitate was recovered by decantation and dried in vacuo to synthesize the product.

[0150] <Preparation of positive electrode> The valve-type nozzle disclosed in Japanese Patent No. 7271956 was attached to an inkjet discharge evaluation device (device name: EV2500, manufactured by Ricoh Co., Ltd.), and the liquid composition for forming a positive electrode composite layer was applied to an aluminum foil current collector with an average thickness of 15 μm. The nozzle spacing (period T) was 2.54 mm. When the applied liquid composition for forming a positive electrode composite layer leveled and coalesced with adjacent droplets and the haze on the liquid surface was no longer visible to the naked eye, the composition was heated and dried at 80°C to obtain a positive electrode.

[0151] (Examples 19 to 28) As shown in Tables 1 to 4, a liquid composition for forming a positive electrode composite layer and a positive electrode were prepared in the same manner as in Example 18, except that the composition of the liquid composition for forming a positive electrode composite layer and / or the period T were changed.

[0152] Example 29 Solid components (active material, binder, conductive additive, dispersant) were mixed in a dispersion medium with the compositions and amounts shown in Tables 1 to 4, and dispersed using a planetary centrifugal stirrer (Mazerustar, manufactured by Kurabo Industries, Ltd.), to obtain a liquid composition for forming a positive electrode composite layer (liquid composition for forming an electrode composite layer). The details of each component are as follows: LiNbO3 / NCM: Lithium niobate coated nickel cobalt manganese oxide Butyl butyrate: manufactured by Tokyo Chemical Industry Co., Ltd. LPSC: Argyrodite-type sulfide solid electrolyte Li6PS5Cl

[0153] [Surface coating of ion-conductive oxides on active materials] The active material used was a nickel-based positive electrode active material (lithium nickel cobalt manganese oxide, hereinafter sometimes referred to as "NCM"; average primary particle diameter: 3.5 μm, manufactured by Toshima Manufacturing Co., Ltd.). LiNbO3 was used as the ion-conductive oxide that coated the surface of the NCM particles. The LiNbO3 layer was formed on the surface of NCM powder particles by hydrolysis of an alkoxide solution containing lithium and niobium, following the published literature (J. Mater. Chem. A. 2021, 9, 4117-4125). First, metallic lithium (Honjo Metals Co., Ltd.) was dissolved in absolute ethanol (Kanto Chemical Co., Ltd.) to prepare an ethanol solution of lithium ethoxide. Niobium pentaethoxide (Nb(OC2H5)5) (Kojundo Chemical Laboratory Co., Ltd.) was then added to this solution to form an alkoxide solution containing lithium and niobium. The NCM powder was fluidized using a tumbling fluidizer (MP-01, Powrex Corporation) and the alkoxide solution was sprayed onto the fluidized bed to obtain a precursor powder with the alkoxide coating on the NCM powder particle surface. This powder was heated at 350 °C in a dry air atmosphere to form a LiNbO3 layer on the NCM surface (hereinafter referred to as "LNO / NCM").

[0154] [Synthesis of Argyrodite-type Sulfide Solid Electrolytes] The argyrodite-type sulfide solid electrolyte Li6PS5Cl (LPSC) was synthesized according to the known literature 1 "J. Power Sources. 2018, 396, 33-40." Specifically, the synthesis is as follows. A sulfide solid electrolyte was obtained by grinding 0.5 g of LiS (99.9%, Mitsuwa Chemical Co., Ltd.), 0.5 g of P2S5 (99%, Sigma-Aldrich), and 0.5 g of LiCl (99%, Sigma-Aldrich) for 40 hours using a planetary ball mill (PULVERISETTE, Fritsch, Germany). The grinding was carried out in a 45 mL zirconia pot using 15 zirconia balls (diameter: 10 mm) at 600 RPM.

[0155] <Preparation of positive electrode> The valve-type nozzle disclosed in Japanese Patent No. 7271956 was attached to an inkjet ejection evaluation device (device name: EV2500, manufactured by Ricoh Co., Ltd.), and the liquid composition for forming a positive electrode composite layer was applied to an aluminum foil current collector with an average thickness of 15 μm. The nozzle spacing (period T) was 1.27 mm. When the applied liquid composition for forming a positive electrode composite layer leveled and coalesced with adjacent droplets and the haze on the liquid surface was no longer visible, the composition was heated and dried at 80°C to obtain a positive electrode.

[0156] Examples 30 to 34 As shown in Tables 1 to 4, a liquid composition for forming a positive electrode mixture layer and a positive electrode were prepared in the same manner as in Example 29, except that the composition of the liquid composition for forming a positive electrode mixture layer and / or the period T were changed.

[0157] (Comparative Example 1) The liquid composition for forming a negative electrode composite layer prepared in Example 1 was applied onto a copper foil current collector having an average thickness of 15 μm using a die coating device (Auto Film Applicator, manufactured by Tester Sangyo Co., Ltd.), and then heated and dried at 80°C to obtain a negative electrode.

[0158] (Comparative Example 2) As shown in Tables 1 to 4, the formulation of the negative electrode composite layer forming liquid composition was changed to obtain a negative electrode composite layer forming liquid composition of Comparative Example 2-1 and a negative electrode composite layer forming liquid composition of Comparative Example 2-2. Copper foil with an average thickness of 10 μm and paraffin film (manufactured by Plastic Packaging Co., Ltd.) with an average thickness of 30 μm were prepared, and 1.25 mm × 20 mm holes were formed in the paraffin film at 2.50 mm intervals. A paraffin film was attached to the copper foil, and the liquid composition for forming a negative electrode composite layer of Comparative Example 2-1 was applied using a doctor blade so as to seal the holes formed in the paraffin film. The resulting sheet was dried at 80°C for 1 minute. The paraffin film was removed from the resulting sheet, and a first electrode composite layer with a diameter of 11 mm was formed on the copper foil. The liquid composition for forming a negative electrode composite layer of Comparative Example 2-2 was applied using a doctor blade so as to cover the base and the first electrode composite layer, thereby forming a second electrode composite layer. The resulting sheet was dried at 80°C for 20 minutes, and then the base and the electrode composite layer were firmly and closely bonded using a roll press. Next, the copper foil on which the first electrode composite layer and the second electrode composite layer were formed was punched out using a circular punch with a diameter of 16 mm. The removed copper foil on which the first electrode mixture layer and the second electrode mixture layer were formed was heated in a vacuum dryer at 120° C. for 3 hours, thereby producing an electrode on which the first electrode mixture layer and the second electrode mixture layer were formed.

[0159] (Comparative Example 3) As shown in Tables 1 to 4, a liquid composition for forming a negative electrode mixture layer and a negative electrode were prepared in the same manner as in Comparative Example 1, except that the formulation of the liquid composition for forming a negative electrode mixture layer was changed.

[0160] Comparative Example 4 A liquid composition for forming a negative electrode mixture layer and a negative electrode were prepared in the same manner as in Comparative Example 3, except that the drying temperature of the liquid composition for forming a negative electrode mixture layer was changed to 25°C.

[0161] (Comparative Example 5) The liquid composition for forming a positive electrode composite layer prepared in Example 18 was applied to an aluminum foil current collector having an average thickness of 15 μm using a die coating device (Auto Film Applicator, manufactured by Tester Sangyo Co., Ltd.), and then heated and dried at 80°C to obtain a negative electrode.

[0162] (Comparative Example 6) As shown in Tables 1 to 4, the formulation of the positive electrode composite layer forming liquid composition was changed to obtain a positive electrode composite layer forming liquid composition of Comparative Example 6-1 and a positive electrode composite layer forming liquid composition of Comparative Example 6-2. Copper foil with an average thickness of 10 μm and a paraffin film (manufactured by Plastic Packaging Co., Ltd.) with an average thickness of 30 μm were prepared, and 1.25 mm × 20 mm holes were formed in the paraffin film at 2.50 mm intervals. A paraffin film was attached to the copper foil, and the liquid composition for forming a negative electrode composite layer of Comparative Example 6-1 was applied using a doctor blade so as to seal the holes formed in the paraffin film. The resulting sheet was dried at 80°C for 1 minute. When the paraffin film was removed from the resulting sheet, a first electrode composite layer with a diameter of 11 mm was formed on the copper foil. The liquid composition for forming a negative electrode composite layer of Comparative Example 6-2 was applied using a doctor blade so as to cover the base and the first electrode composite layer, thereby forming a second electrode composite layer. The resulting sheet was dried at 80°C for 20 minutes, and then the base and the electrode composite layer were firmly and closely bonded using a roll press. Next, the copper foil on which the first electrode composite layer and the second electrode composite layer were formed was punched out using a circular punch with a diameter of 16 mm. The removed copper foil on which the first electrode mixture layer and the second electrode mixture layer were formed was heated in a vacuum dryer at 120° C. for 3 hours, thereby producing an electrode on which the first electrode mixture layer and the second electrode mixture layer were formed.

[0163] (Comparative Example 7) With reference to JP 2023-138315 A, an industrial inkjet head (MH5420, manufactured by Ricoh Co., Ltd.) was attached to an inkjet ejection evaluation device (device name: EV2500, manufactured by Ricoh Co., Ltd.), and the liquid composition for forming a positive electrode composite layer was applied to an aluminum foil current collector with an average thickness of 15 μm. The liquid composition for forming an electrode composite layer was applied to the current collector so that the distance between the apex of adjacent convex portions and the apex of non-convex portions was 125 μm, and h3 (h2-h1), which is the height h2 of the convex portions minus the height h1 of the non-convex portions, was 8 μm. The positive electrode composite layer had multiple convex portions, and was then heated to 120°C on a hot plate and dried. This process was repeated a total of 10 times to obtain a layer with a basis weight of 20 mg / cm. 2The mixture was pressed with a 7-ton hydraulic roll press (manufactured by Thank Metal Co., Ltd.) to obtain a positive electrode.

[0164] The electrodes obtained in each Example and Comparative Example were subjected to the following evaluations: thixotropy index measurement, continuity and periodicity measurement, average thickness evaluation, average porosity evaluation, binder concentration in the film thickness direction evaluation, rate performance evaluation, and cycle performance evaluation. The results are shown in Tables 5 to 8.

[0165] [Thixotropy index measurement] The viscosities of the obtained liquid compositions were measured at room temperature (25°C) at 100 rpm and 10 rpm using a TV25 viscometer (cone-plate type viscometer, manufactured by Toki Sangyo Co., Ltd.). The thixotropy index (TI) was calculated as the viscosity at 10 rpm / the viscosity at 100 rpm. The results are shown in Tables 5 to 8.

[0166] [Measurement of continuity and periodicity] - Method A: When the binder contains characteristic elements - The base resin (Lot No. 53512040149, Sankei Co., Ltd.) and curing agent (Lot No. 53572040342, Sankei Co., Ltd.) for 53-type embedding epoxy resin were thoroughly mixed at a volume ratio of 1:2. Using a vacuum impregnation device (Buehler Vacuum Impregnation Equipment I, Sankei Co., Ltd.), the electrode composite layer was embedded in the resin and cured for 24 hours. The electrode composite layer embedded in the epoxy resin was processed using a cross-section polisher (JEOL Ltd.), and the cross section was observed using a tabletop scanning electron microscope (SEM / EDX) (Phenom Prox, Jasco International Inc.) to perform elemental mapping of the cross section of the electrode composite layer. The period was calculated from the binder concentration distribution in the X and Y directions, and continuity was confirmed. Even if the binder does not contain a characteristic element, if the binder can be stained by an electron staining method using osmium tetroxide or ruthenium tetroxide, element mapping was performed by carrying out this method.

[0167] -Method B: When the binder does not contain characteristic elements- Using a surface and interface properties analyzer (SAICAS), the electrode composite layer was cut at intervals 1 / 10 smaller than the period expected from the manufacturing method. The collected samples were subjected to pyrolysis GC / MS analysis to obtain the peak values ​​of fragments derived from the binder. The binder concentration was quantified by applying this to a calibration curve obtained using binders of known concentration. The period was calculated by plotting the binder concentration in each sample.

[0168] [Average thickness evaluation] -Method A: When the binder contains characteristic elements- In the method A of [Measurement of continuity and period], the binder concentration of the entire cross section is the average binder concentration C Ave The binder concentration in the X or Y direction was averaged in the thickness (Z) direction to calculate the average binder concentration C Ave Region A where the binder concentration is higher than High , low area A Low Area A High Average thickness t High and area A Low Average thickness t Low were measured and compared.

[0169] -Method B: When the binder does not contain characteristic elements- In Method B of [Measurement of continuity and period], when excavating with SAICAS, the distance (film thickness) until reaching the substrate is acquired and correlated with the previous period. High Average thickness t High and area A Low Average thickness t Low were calculated and compared.

[0170] [Evaluation of average porosity] -Method A: When the binder contains characteristic elements- In Method A of [Measurement of continuity and period], the SEM photograph of the obtained electrode composite layer was binarized using image processing software (Image-Pro Premier version 9.2 64-bit, manufactured by Hakuto Co., Ltd.) to identify Region A. High and Area A Low By calculating the area of ​​the region originating from particles and the area originating from voids, the area A High Porosity φ in High and area A Low Porosity φ in Low Whether or not the cutting has reached the substrate can be easily determined from the stress profile during cutting.

[0171] -Method B: When the binder does not contain characteristic elements- From the average thickness and excavation width obtained in Method B of [Measurement of continuity and period], High Porosity φ in High and area A Low Porosity φ in Low was calculated and compared.

[0172] [Evaluation of binder concentration in the film thickness direction] -Method A: When the binder contains characteristic elements- In the method A of [Measurement of continuity and period], from the base, area A High Average thickness t High Divide the above into two equal parts, and A High,Surface , A High,Under A High,Surface Average binder concentration C High,Surface , A High,Under Average binder concentration C High,Under were measured and compared.

[0173] -Method B: When the binder does not contain characteristic elements- The distance from the average thickness obtained in Method B of [Measurement of continuity and period] to the substrate was divided into two equal parts, excavated, and quantitatively evaluated by pyrolysis GC / MS. High,Surface Average binder concentration C High,Surface , AHigh,Under Average binder concentration C High,Under was calculated and compared.

[0174] [Evaluation of rate characteristics] The rate characteristics of each positive electrode or each negative electrode were measured using a charge / discharge measuring device (TOSCAT3001, manufactured by Toyo Systems Co., Ltd.). The prepared positive electrode was punched into a round shape with a diameter of 16 mm, and then placed in a coin can with the positive or negative electrode, a 100 μm thick glass separator D (manufactured by ADVANTEC Co., Ltd.), an electrolyte (1.5 mol / L LiPF6 / (ethylene carbonate (EC): dimethyl carbonate (DMC): ethyl methyl carbonate (EMC) (1:1:1 v / v%) + 10% fluoroethylene (FEC) (manufactured by Kishida Chemical Co., Ltd.)), and a 200 μm thick lithium foil (manufactured by Honjo Metals Co., Ltd.) as a counter electrode, to prepare an electrochemical device. When the evaluation target was the positive electrode, the fabricated electrochemical element was charged at a constant current up to 4.2 V at C rates of 0.2 C, 1.0 C, 2.0 C, 3.0 C, 4.0 C, and 5.0 C at room temperature (25°C), and then discharged at a constant current down to 3.0 V to measure the charge / discharge capacity. Furthermore, the rate characteristics were evaluated using the ratio of the discharge capacity at 0.2 C to the discharge capacity at 5.0 C as the capacity retention rate. When the evaluation target was the negative electrode, the rate characteristics were evaluated under the same conditions as for the positive electrode, except that the constant current charge was limited to 2.0 V and the constant current discharge was limited to 0.05 V. When the evaluation target was a positive electrode for an all-solid-state battery, a 100 μm thick solid electrolyte was used instead of a glass separator and an electrolyte, and a 200 μm thick indium (manufactured by Honjo Metals Co., Ltd.) and a 200 μm thick lithium (manufactured by Honjo Metals Co., Ltd.) were used instead of lithium foil as the counter electrode. The applied voltage range was 2.4 V to 3.7 V. For comparison, rate characteristics were evaluated using an electrode without a periodic binder concentration distribution, which was prepared by applying a liquid composition for forming an electrode mixture layer of the same composition to a current collector foil with an applicator and drying it. The capacity retention rate of the flat electrode used for comparison was set at 100, and the rate characteristics were evaluated relative to this. The pass standard was "△△" or better. <Evaluation criteria> ◎: (Capacity maintenance rate of evaluation target / Capacity maintenance rate of comparison target x 100) is 115 or more and less than 120 ○: (Capacity maintenance rate of the evaluation target / Capacity maintenance rate of the comparison target x 100) is 110 or more and less than 115 △: (Capacity maintenance rate of the evaluation target / Capacity maintenance rate of the comparison target x 100) is 105 or more and less than 110 △△: (Capacity maintenance rate of the evaluation target / Capacity maintenance rate of the comparison target x 100) is 100 or more and less than 105 ×: (Capacity maintenance rate of the evaluation target / Capacity maintenance rate of the comparison target x 100) is less than 100

[0175] [Evaluation of cycle characteristics] The capacity retention rate of each positive electrode or each negative electrode was measured using a charge / discharge measuring device (TOSCAT3001, manufactured by Toyo Systems Co., Ltd.). The prepared positive electrode was punched into a round shape with a diameter of 16 mm, and then placed in a coin can with the positive or negative electrode, a 100 μm thick glass separator D (manufactured by ADVANTEC Co., Ltd.), an electrolyte (1.5 mol / L LiPF6 / (ethylene carbonate (EC): dimethyl carbonate (DMC): ethyl methyl carbonate (EMC) (1:1:1 v / v%) + 10% fluoroethylene (FEC) (manufactured by Kishida Chemical Co., Ltd.)), and a 200 μm thick lithium foil (manufactured by Honjo Metals Co., Ltd.) as a counter electrode, to prepare an electrochemical device. When the evaluation target was a positive electrode, the prepared electrochemical element was subjected to a cycle charge-discharge test at room temperature (25°C) by charging at a constant current of 2.0 C to 4.2 V and then discharging at a constant current of 3.0 V. The first charge-discharge cycle was performed by charging at a constant current of 0.2 C to 4.2 V and then discharging at a constant current of 3.0 V. The discharge capacity was measured as the initial discharge capacity A per unit area of ​​the positive electrode. After 500 charge-discharge cycles, the element was charged at a constant current of 0.2 C to 4.2 V and then discharged at a constant current of 3.0 V. The discharge capacity was measured as the discharge capacity B per unit area of ​​the positive electrode. The capacity retention rate of the positive electrode was calculated using equation (5). Capacity retention rate (%) = (discharge capacity B / discharge capacity A) × 100...Formula (5) When the negative electrode was evaluated, the electrochemical element was subjected to a cycle charge-discharge test at room temperature (25°C) by charging at a constant current of 2.0 C to 2.0 V and then discharging at a constant current of 0.05 V. The first charge-discharge cycle consisted of charging at a constant current of 0.2 C to 2.0 V and then discharging at a constant current of 0.05 V. The discharge capacity was measured as the initial discharge capacity A per unit area of ​​the positive electrode. After 500 charge-discharge cycles, the device was charged at a constant current of 0.2 C to 2.0 V and then discharged at a constant current of 0.05 V. The 500th charge-discharge cycle consisted of charging at a constant current of 0.2 C to 2.0 V and then discharging at a constant current of 0.05 V. The capacity retention rate of the negative electrode was calculated using equation (6). Capacity retention rate (%) = (discharge capacity B / discharge capacity A) × 100...Formula (6) When the evaluation target was a positive electrode for an all-solid-state battery, a 100 μm thick solid electrolyte was used instead of a glass separator and an electrolyte, and a 200 μm thick indium (manufactured by Honjo Metals Co., Ltd.) and a 200 μm thick lithium (manufactured by Honjo Metals Co., Ltd.) were used instead of lithium foil as the counter electrode. The applied voltage range was 2.4 V to 3.7 V. For comparison, rate characteristics were evaluated using an electrode without a periodic binder concentration distribution, which was created by applying an electrode mixture layer-forming liquid composition of the same composition to a current collector foil with an applicator and drying it. The capacity retention rate of the comparison flat electrode was set at 100, and the rate characteristics were evaluated relative to this. The pass standard was "△△" or better. <Evaluation criteria> ◎: (Capacity maintenance rate of evaluation target / Capacity maintenance rate of comparison target x 100) is 115 or more and less than 120 ○: (Capacity maintenance rate of the evaluation target / Capacity maintenance rate of the comparison target x 100) is 110 or more and less than 115 △: (Capacity maintenance rate of the evaluation target / Capacity maintenance rate of the comparison target x 100) is 105 or more and less than 110 △△: (Capacity maintenance rate of the evaluation target / Capacity maintenance rate of the comparison target x 100) is 100 or more and less than 105 ×: (Capacity maintenance rate of the evaluation target / Capacity maintenance rate of the comparison target x 100) is less than 100

[0176] [Table 1]

[0177] [Table 2]

[0178] [Table 3]

[0179] [Table 4]

[0180] [Table 5]

[0181] [Table 6]

[0182] [Table 7]

[0183] [Table 8]

[0184] The results of Examples 1 to 34 show that excellent cycle characteristics can be obtained when the period T is 0.2 mm or more and 2.5 mm or less. In particular, when the period T is in the range of 0.4 mm or more and 1.7 mm or less, an electrode with even better cycle characteristics can be obtained, and when the period T is in the range of 0.6 mm or more and 1.3 mm or less, an electrode with extremely excellent cycle characteristics can be obtained. From the results of Example 8, it can be seen that as the solid content concentration or viscosity of the liquid composition for forming a negative electrode mixture layer increases, the time from when the droplets coalesce to when they spread out becomes longer, and t High <t LowAs a result, it is possible to obtain an electrode that satisfies the above condition. As a result, it is found that an electrode having excellent cycle characteristics can be obtained. From the results of Example 9, it was found that the pressing process reduced the diameter of the High >φ Low As a result, it is possible to obtain an electrode that has excellent cycle characteristics and volumetric energy density. From the results of Examples 10 and 26, it was found that by further increasing the solid content concentration, High and t Low The difference between the two is larger, and even after the pressing process, High <t Low and φ High >φ Low As a result, it is possible to obtain an electrode that has excellent cycle characteristics and volumetric energy density. From the results of Examples 11 to 14, it was found that the use of a soluble binder High,Surface >A High,Under As a result, it is possible to obtain a negative electrode that satisfies the above condition. As a result, it is possible to obtain an electrode that has better cycle characteristics.

[0185] The results of Comparative Examples 1 and 5 show that excellent cycle characteristics cannot be obtained unless the binder concentration in the electrode mixture layer is changed periodically. The results of Comparative Examples 2 and 6 show that excellent cycle characteristics cannot be obtained when the binder concentration in the electrode mixture layer is not continuous. From the results of Comparative Example 7, even if the inkjet method was used, a manufacturing method in which coating and drying were performed multiple times did not provide a periodic binder concentration distribution, and no improvement in cycle characteristics was confirmed.

[0186] The results of Example 17 and Comparative Example 3 show that even when only SiO is used as the negative electrode active material, excellent cycle characteristics can be obtained only when the binder concentration in the electrode mixture layer changes periodically. Furthermore, the negative electrode produced in Comparative Example 4 was visually observed to have uniform binder segregation on the negative electrode surface layer due to the low drying temperature and long drying time. This means that the negative electrode has a binder concentration distribution only in the thickness direction (the binder concentration is uniformly high on the surface layer side), and in this case, it is clear that excellent rate characteristics cannot be obtained (the movement of the electrolyte is hindered because the entire surface is covered with the binder).

[0187] The present invention includes, for example, the following aspects. <1> a substrate; an electrode mixture layer provided on the substrate, the electrode mixture layer contains an active material and a binder, The electrode is characterized in that the binder concentration in the electrode mixture layer varies periodically and continuously in at least one direction perpendicular to the thickness direction of the electrode mixture layer. <2> The period of the binder concentration is 0.2 mm or more and 2.5 mm or less. <1> The electrode is described in <3> The region where the binder concentration is higher than the average binder concentration in the electrode mixture layer is referred to as region A. High The region where the binder concentration is low relative to the average binder concentration in the electrode mixture layer is defined as region A. Low When Area A High Average thickness t High and the region A Low Average thickness t Low The following formula (1) is satisfied: <1> or <2> The electrode is described in t High <t Low ...Equation (1) <4> The region where the binder concentration is higher than the average binder concentration in the electrode mixture layer is referred to as region A. HighThe region where the binder concentration is low relative to the average binder concentration in the electrode mixture layer is defined as region A. Low When Area A High Average porosity φ in High and the region A Low Average porosity φ in Low means that the following formula (2) is satisfied: <1> from <3> The electrode is any one of the above. φ High >φ Low ...Equation (2) <5> The region where the binder concentration is higher than the average binder concentration in the electrode mixture layer is referred to as region A. High year, Area A High Average thickness t High The region of the electrode mixture layer on the substrate side is defined as region A, based on a virtual line that divides the electrode mixture layer into two equal parts in a direction perpendicular to the thickness direction of the electrode mixture layer. High,Under The region of the electrode mixture layer that is not on the substrate side is referred to as region A High,surface When we do this, Area A High,Under Average binder concentration C High,Under and the region A High,surface Average binder concentration C High,surface means that the following formula (3) is satisfied: <1> from <4> The electrode is any one of the above. C High,Under <C High,surface ...Equation (3) <6> A method for manufacturing an electrode, comprising: forming an electrode mixture layer on a substrate; The electrode mixture layer forming step includes: an electrode mixture layer forming liquid composition application step of applying an electrode mixture layer forming liquid composition containing an active material, a binder, and a dispersion medium onto the substrate; an electrode mixture layer forming liquid composition drying step of drying the applied electrode mixture layer forming liquid composition, The electrode mixture layer is a method for manufacturing an electrode, characterized in that the binder concentration in the electrode mixture layer varies periodically and continuously in at least one direction perpendicular to the thickness direction of the electrode mixture layer. <7> the electrode mixture layer forming liquid composition applying step applies the electrode mixture layer forming liquid composition onto the substrate at a period of 0.2 mm or more and 2.5 mm or less; <6> 2. A method for producing the electrode according to claim 1. <8> In the electrode mixture layer forming liquid composition drying step, the electrode mixture layer forming liquid composition is dried before being flattened. <6> or <7> 10. A method for producing an electrode according to any one of the preceding claims. <9> a waiting step between the electrode mixture layer forming liquid composition applying step and the electrode mixture layer forming liquid composition drying step, <6> from <8> 10. A method for producing an electrode according to any one of the preceding claims. <10> In the electrode mixture layer forming liquid composition, the binder is dissolved in the dispersion medium. <6> from <9> 10. A method for producing an electrode according to any one of the preceding claims. <11> Including the pressing process, <6> from <10> 2. A method for producing the electrode according to claim 1.

[0188] <1> from <5> The electrode according to any one of the preceding claims, and <6> from <11> The electrode manufacturing method described in any one of the above can solve the various problems in the prior art and achieve the object of the present invention. [Explanation of symbols]

[0189] 1 Base 2 Electrode composite layer 12A Liquid composition for forming electrode composite layer 100 printing department 200 Heating section 500 Electrode manufacturing equipment [Prior art documents] [Patent documents]

[0190] [Patent Document 1] Patent No. 3482443 [Patent Document 2] Patent No. 5403153

Claims

1. a substrate; an electrode mixture layer provided on the substrate, the electrode mixture layer contains an active material and a binder, An electrode, characterized in that the binder concentration in the electrode mixture layer varies periodically and continuously in at least one direction perpendicular to the thickness direction of the electrode mixture layer.

2. The electrode according to claim 1 , wherein the period of the binder concentration is 0.2 mm or more and 2.5 mm or less.

3. The region where the binder concentration is higher than the average binder concentration in the electrode mixture layer is referred to as region A. Ｈｉｇｈ The region where the binder concentration is low relative to the average binder concentration in the electrode mixture layer is defined as region A. Ｌｏｗ When The region A Ｈｉｇｈ Average thickness t Ｈｉｇｈ and the region A Ｌｏｗ Average thickness t Ｌｏｗ The electrode according to claim 1 or 2, which satisfies the following formula (1): t Ｈｉｇｈ <t Ｌｏｗ Formula (1)

4. The region where the binder concentration is higher than the average binder concentration in the electrode mixture layer is referred to as region A. Ｈｉｇｈ The region where the binder concentration is low relative to the average binder concentration in the electrode mixture layer is defined as region A. Ｌｏｗ When The region A Ｈｉｇｈ Average porosity φ in Ｈｉｇｈ and the region A Ｌｏｗ Average porosity φ in Ｌｏｗ The electrode according to claim 1 or 2, which satisfies the following formula (2): f Ｈｉｇｈ >φ Ｌｏｗ ・・・formula (2)

5. The region where the binder concentration is higher than the average binder concentration in the electrode mixture layer is referred to as region A. Ｈｉｇｈ year, The region A Ｈｉｇｈ Average thickness t Ｈｉｇｈ The region of the electrode mixture layer on the substrate side is defined as region A, based on a virtual line that divides the electrode mixture layer into two equal parts in a direction perpendicular to the thickness direction of the electrode mixture layer. Ｈｉｇｈ，Ｕｎｄｅｒ The region of the electrode mixture layer that is not on the substrate side is referred to as region A. Ｈｉｇｈ，ｓｕｒｆａｃｅ When we do this, The region A Ｈｉｇｈ，Ｕｎｄｅｒ Average binder concentration C Ｈｉｇｈ，Ｕｎｄｅｒ and the region A Ｈｉｇｈ，ｓｕｒｆａｃｅ Average binder concentration C Ｈｉｇｈ，ｓｕｒｆａｃｅ The electrode according to claim 1 or 2, which satisfies the following formula (3): C Ｈｉｇｈ，Ｕｎｄｅｒ <C Ｈｉｇｈ，ｓｕｒｆａｃｅ Formula (3)

6. A method for manufacturing an electrode, comprising: forming an electrode mixture layer on a substrate; The electrode mixture layer forming step includes: an electrode mixture layer forming liquid composition application step of applying an electrode mixture layer forming liquid composition containing an active material, a binder, and a dispersion medium onto the substrate; an electrode mixture layer forming liquid composition drying step of drying the applied electrode mixture layer forming liquid composition, The electrode mixture layer is characterized in that the binder concentration in the electrode mixture layer varies periodically and continuously in at least one direction perpendicular to the thickness direction of the electrode mixture layer.

7. The method for manufacturing an electrode according to claim 6 , wherein the electrode mixture layer forming liquid composition applying step applies the electrode mixture layer forming liquid composition onto the substrate at a period of 0.2 mm or more and 2.5 mm or less.

8. The method for manufacturing an electrode according to claim 6 or 7, wherein the electrode mixture layer forming liquid composition drying step dries the electrode mixture layer forming liquid composition before the electrode mixture layer forming liquid composition is planarized.

9. The method for producing an electrode according to claim 6 or 7, further comprising a waiting step between the step of applying the electrode mixture layer forming liquid composition and the step of drying the electrode mixture layer forming liquid composition.

10. The method for producing an electrode according to claim 6 or 7, wherein the binder is dissolved in the dispersion medium in the electrode mixture layer forming liquid composition.

11. The method for producing an electrode according to claim 6 or 7, further comprising a pressing step.

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