Electrode and method for manufacturing the same

Abstract

To provide a method for manufacturing an electrode excellent in rate characteristics.SOLUTION: A method for manufacturing an electrode comprising an electrode mixture layer having a periodic uneven structure on its surface is provided. The method for manufacturing an electrode includes an electrode mixture layer formation liquid composition application step of applying an electrode mixture layer formation liquid composition containing an active material and a dispersion medium onto a substrate, at an application period of 0.28 mm or more and 1.7 mm or less, by using a liquid discharge device having a plurality of nozzle holes arranged side by side in parallel in a parallel direction with a substrate surface.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 such diversifying needs for electrochemical devices, electrodes having a sparsely packed structure have been proposed for the purpose of improving battery characteristics.

[0003] A method for manufacturing a non-aqueous electrolyte secondary battery including an electrode mixture layer having a concave-convex structure has been proposed (see, for example, Patent Document 1), in which a mold having a concave-convex pattern is pressed against a flatly formed electrode mixture layer to transfer the concave-convex pattern. A method for manufacturing a battery electrode has been proposed in which a new electrode mixture layer having a sparsely packed structure is formed by applying a new electrode mixture layer-forming liquid composition to a location on a flatly formed electrode mixture layer where a high-density region is desired and then drying the liquid composition (see, for example, Patent Document 2). An electrode has been proposed in which the electrode mixture layer has a uniform porosity and has multiple convex shapes, with the porosity of the convex portions and the porosity of the non-convex portions specified, in order to improve the capacity retention rate (see, for example, Patent Document 3). Other methods proposed include a method of obtaining a striped electrode composite layer using a dispenser (see, for example, Non-Patent Document 1) and a method of obtaining a striped electrode composite layer by screen printing (see, for example, Non-Patent Document 2). Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a method for producing an electrode having excellent rate characteristics. [Means for solving the problem]

[0005] The method for producing an electrode of the present invention as a means for solving the above problems comprises the steps of: A method for manufacturing an electrode having an electrode composite layer with a periodic uneven structure on its surface, the method for manufacturing an electrode includes a liquid composition application step of applying an electrode composite layer forming liquid composition containing an active material and a dispersion medium onto the substrate at an application period of 0.28 mm or more and 1.7 mm or less, using a liquid ejection device having a plurality of nozzle holes arranged in a direction parallel to the substrate surface. [Effects of the Invention]

[0006] According to the present invention, a method for producing an electrode having excellent rate characteristics can be provided. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a schematic diagram for explaining the period of electrode irregularities in the present invention. [Figure 2] 1A and 1B are schematic diagrams illustrating the structure of a liquid ejection device according to the present invention. [Figure 3] 1 is a schematic diagram illustrating a liquid ejection device according to an embodiment of the present invention. [Figure 4A] 1 is a schematic cross-sectional view showing an electrode obtained by a method for producing an electrode according to one embodiment of the present invention. [Figure 4B] 1 is a schematic cross-sectional view for explaining the mechanism by which a periodic electrode uneven structure is formed in an electrode obtained by a manufacturing method of an electrode according to one embodiment of the present invention. FIG. [Figure 5A] 1 is a schematic cross-sectional view showing an electrode obtained by a method for producing an electrode according to one embodiment of the present invention. [Figure 5B] FIG. 4 is a schematic cross-sectional view showing an electrode obtained by a method for producing an electrode according to another embodiment of the present invention. [Figure 6] 1 is a schematic diagram showing an electrode manufacturing apparatus according to an embodiment of the present invention. [Figure 7]FIG. 10 is a schematic diagram showing an electrode manufacturing apparatus according to another embodiment of the present invention. [Figure 8] FIG. 10 is a schematic diagram showing an electrode manufacturing apparatus according to another embodiment of the present invention. [Figure 9] FIG. 10 is a schematic diagram showing a modified example of an electrode manufacturing apparatus according to an embodiment of the present invention. [Figure 10] FIG. 1 is a configuration 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 mixture layer in an electrode manufacturing apparatus according to one embodiment of the present invention. [Figure 11] FIG. 2 is a structural 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 mixture layer in an electrode manufacturing apparatus according to one embodiment of the present invention. [Figure 12] 3A to 3C are schematic diagrams 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 13] 5A to 5C are schematic diagrams showing other examples of the formation pattern of the electrode mixture layer in the manufacturing method of the electrode according to one embodiment of the present invention. [Figure 14] 1 is a schematic cross-sectional view showing an electrochemical element according to one embodiment of the present invention. [Figure 15] FIG. 2 is a schematic cross-sectional view showing an electrochemical device according to another embodiment of the present invention. [Figure 16] 1 is a schematic diagram showing a moving body that is an electrochemical element according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] The transfer method using a concave-convex mold as in Patent Document 1 inevitably results in a large porosity in the convex portions. Therefore, if the electrode mixture layer is thick, there is a concern that the electronic resistance of the convex portions will be high and sufficient rate characteristics will not be obtained. Furthermore, there is a problem in that the convex portions are fragile, which can cause damage to the electrode mixture layer during the manufacturing process.

[0009] The multi-coating method described in Patent Document 2 requires multiple coating steps, leaving room for improvement in terms of productivity. In addition, there is a tendency for film strength to decrease at the interfaces of the stacked electrode mixture layers, which can lead to damage to the electrode mixture layers during the manufacturing process.

[0010] In the inkjet method as disclosed in Patent Document 3, the viscosity of the liquid composition for forming an electrode mixture layer is low, so that in order to vary the film thickness during formation and form an electrode mixture layer having an uneven structure, it is necessary to perform multiple coating steps with drying steps in between. Therefore, there is room for improvement in terms of productivity.

[0011] The dispenser method described in Non-Patent Document 1 requires multiple scans for long-term drawing. Therefore, there is room for improvement in terms of productivity. Furthermore, the liquid composition applied immediately after the start of drawing and the liquid composition applied immediately before the end of drawing require different times before moving on to the drying process, which can lead to problems such as unevenness in the shape of the projections and recesses and non-uniform composition of the electrode mixture layer.

[0012] The screen printing method as described in Non-Patent Document 2 has a problem in that the current collector has exposed portions due to its structure, which reduces the overall capacity of the battery.

[0013] The method for manufacturing an electrode according to the present invention is a method for manufacturing an electrode having an electrode composite layer having a periodic uneven structure on its surface, and includes a liquid composition application step of applying an electrode composite layer forming liquid composition containing an active material and a dispersion medium onto the substrate at an application period of 0.28 mm or more and 1.7 mm or less, using a liquid ejection device having a plurality of nozzle holes arranged in a direction parallel to the substrate surface. Such a configuration can sufficiently resolve various concerns in the prior art, and more specifically, can realize a method for manufacturing an electrode with excellent rate characteristics.

[0014] The present invention will be described in detail below.

[0015] (Electrode manufacturing method and electrode manufacturing device) The method for manufacturing an electrode according to the present invention is a method for manufacturing an electrode comprising an electrode mixture layer having a periodic uneven structure on its surface, and the method for manufacturing an electrode includes a step of applying a liquid composition for forming an electrode mixture layer, and may also include a step of drying the liquid composition for forming an electrode mixture layer and other steps as necessary. The electrode manufacturing apparatus according to the present invention is an electrode manufacturing apparatus that includes an electrode mixture layer having a periodic uneven structure on its surface, and the electrode manufacturing apparatus has a means for applying a liquid composition for forming an electrode mixture layer, and may also have a means for drying the liquid composition for forming an electrode mixture layer and other means, as necessary. The electrode manufacturing method can be suitably carried out by the electrode manufacturing apparatus, the electrode mixture layer forming liquid composition application step can be suitably carried out by electrode mixture layer forming liquid composition application means, the electrode mixture layer forming liquid composition drying step can be suitably carried out by electrode mixture layer forming liquid composition drying means, and the other steps can be suitably carried out by other means.

[0016] The electrode manufactured by the electrode manufacturing method according to the present invention comprises a substrate and an electrode mixture layer on the substrate, the electrode mixture layer having a periodic uneven structure on its surface, wherein the ratio (h1 / h2) of the height h1 (μm) of the recesses of the electrode mixture layer to the height h2 (μm) of the protrusions of the electrode mixture layer is 0.71 or more and 0.95 or less. The periodic uneven structure on the surface of the electrode mixture layer increases the surface area and improves electrolyte permeability compared to when the electrode mixture layer is flat, resulting in excellent rate characteristics.

[0017] In this specification, the height of the convex portion relative to the bottom of the electrode mixture layer is defined as h2, and the height of the concave portion is defined as h1. However, if a pressing process is included in forming the electrode mixture layer, the range of the ratio (h1 / h2) indicates the range of the ratio (h1 / h2) before the pressing process.

[0018] In this specification, a "periodic uneven structure" refers to a structure in which unevenness is alternately and periodically arranged, as shown in Fig. 1. The period in the electrode (electrode mixture layer) is sometimes referred to as an "electrode unevenness period" to avoid confusion with the given period, and the structure is sometimes referred to as an "electrode unevenness periodic structure." Fig. 1(a) is a schematic diagram showing an example of an electrode mixture layer as viewed from above, and Fig. 1(b) is a schematic cross-sectional view showing an example of an electrode mixture layer as viewed from the side.

[0019] In this specification, the electrode unevenness period corresponds to the distance from the apex of adjacent convex portions in the direction perpendicular to the substrate transport direction, and is defined as the value obtained by dividing the distance between n consecutively adjacent convex portions (T1→n) by the number of intervals n-1.

[0020] The electrode concave-convex period can be controlled, for example, by changing the nozzle spacing or discharge interval of the liquid discharge device or the workpiece transport time in the electrode mixture layer forming liquid composition application step described below. The periodic structure of the electrode unevenness is controlled by the ejection frequency and the transport speed in the transport direction of the substrate, and the period becomes shorter as the ejection frequency increases or the transport speed decreases, while the period becomes longer as the ejection frequency decreases and the transport speed increases. In the direction perpendicular to the transport speed of the substrate, the periodic structure of the electrode unevenness is controlled by the distance between the midpoints of the nozzles that eject droplets.

[0021] The method for measuring the electrode concave-convex period is not particularly limited and can be appropriately selected depending on the purpose. An example is shown below. Observe using a laser microscope VK-X3000 (manufactured by KEYENCE) equipped with a white light interferometer to obtain a cross-sectional unevenness profile, and measure the average period.

[0022] <Electrode mixture layer forming liquid composition applying step and electrode mixture layer forming liquid composition applying means> The electrode mixture layer forming liquid composition application step is a step of applying an electrode mixture layer forming liquid composition containing an active material and a dispersion medium onto a substrate using a liquid ejection device at an application period of 0.28 mm or more and 1.7 mm or less. The electrode mixture layer forming liquid composition applying means is a means for applying the electrode mixture layer forming liquid composition containing an active material and a dispersion medium onto the substrate at an application period of 0.28 mm to 1.7 mm, i.e., a liquid ejection device.

[0023] The application period in this specification refers to a period set by the nozzle interval, the ejection interval, etc. when forming the electrode mixture layer, and does not necessarily have to match the electrode concave-convex period formed thereby.

[0024] The period of application is 0.28 mm or more, preferably 0.40 mm or more, from the viewpoint of improving the rate characteristics, that is, the effect of infusing the liquid into the electrode layer by increasing the membrane surface area through the formation of the electrode concave-convex periodic structure. The application period is 1.7 mm or less, preferably 1.3 mm or less, from the viewpoint of improving the rate characteristics by increasing the membrane surface area through the formation of the electrode uneven periodic structure. If the application period exceeds 1.7 mm, it may be difficult to form a sufficient electrode uneven periodic structure by coalescence of droplets or liquid.

[0025] <Electrode Mixture Layer Forming Liquid Composition Applying Means (Liquid Discharge Device)> The liquid ejection device has a discharge head having a plurality of nozzle holes arranged in a direction parallel to the surface of the substrate. In other words, as shown in Fig. 2, the liquid ejection device has a discharge head having a plurality of nozzles at equal intervals when the nozzles are projected onto a virtual axis perpendicular to the transport direction of the substrate. The liquid ejection device may have a plurality of such discharge heads. The liquid ejection device may also have other components as necessary (see Fig. 3). Note that Fig. 2 (a) to (d) are schematic diagrams showing the nozzle formation surface of the discharge head.

[0026] The means for applying the electrode mixture layer-forming liquid composition (liquid ejection device) is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include an inkjet method, etc. The inkjet method is preferably used because it can print on a substrate in a non-contact manner and in any shape depending on the purpose.

[0027] Examples of ejection heads used in inkjet systems include piezo heads, thermal heads, valve heads, etc. Among these, the valve head system is preferred from the viewpoint of being excellent in ejecting high-viscosity liquid compositions such as active materials with large ejection hole diameters and relatively large particle sizes, and high-solids liquid compositions and non-spherical compositions such as carbon nanotubes and carbon nanofibers.

[0028] The nozzle diameter is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of suppressing dripping from the nozzle and forming a good image, the nozzle diameter is preferably 70 μm or more. From the viewpoint of suppressing clogging of single particles or aggregates of the positive electrode active material, negative electrode active material, etc. and improving ejection stability, the nozzle diameter is more preferably 100 μm or more, and even more preferably 150 μm or more.

[0029] <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".

[0030] <Liquid composition for forming electrode mixture layer> The electrode mixture layer-forming liquid composition contains an active material and a dispersion medium, and may also contain a binder, a dispersant, a conductive additive, a solid electrolyte, and other components as necessary.

[0031] <<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.

[0032] -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.

[0033] 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.

[0034] -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.

[0035] The particle size 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 particle size of the active material is 0.5 μm or more and 20 μm or less, ejection defects are less likely to occur when the liquid composition for forming an electrode mixture layer is ejected by a liquid ejection means. Furthermore, when the particle size of the active material is 3 μm or more and 10 μm or less, an electrode with better battery characteristics can be obtained. In this specification, the particle size was calculated as the maximum value of the particle size distribution of the active material in the liquid composition for forming an electrode mixture layer.

[0036] The method for measuring the particle size of the active material is not particularly limited and can be appropriately selected depending on the purpose. For example, the particle size can be measured 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.

[0037] <<Binder>> The binder is not particularly limited and can be appropriately selected depending on the purpose as long as it can bind the active materials together and the active materials and the substrate together. For example, a polymer compound can be used.

[0038] The polymer compound is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include polyvinylidene fluoride (PVdF), acrylic resin, polyethylene, polypropylene, polyurethane, nylon, polytetrafluoroethylene, polyphenylene sulfide, polyethylene terephthalate, polybutylene terephthalate, polyamide compounds, polyimide compounds, polyamideimide, ethylene-propylene-butadiene rubber (EPBR), styrene-butadiene rubber (SBR), nitrile butadiene rubber (NBR), isoprene rubber, polyisobutene, and the like. Examples include tenen, polyethylene glycol (PEO), polymethyl methacrylate (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.

[0039] The binder may be dissolved in the electrode mixture layer forming liquid composition or may be dispersed as particles, that is, the electrode mixture layer forming liquid composition may be in the form of a so-called emulsion.

[0040] The binder content is not particularly limited and can be set appropriately depending on the purpose, but is preferably 0.5% by mass or more relative to the total amount of active material from the viewpoint of improving the film strength of the active material, and is preferably 15% by mass or less relative to the total amount of active material from the viewpoint of suppressing a deterioration in battery characteristics due to a decrease in the coverage rate of the active material surface. The binder content is 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, relative to the total amount of active material.

[0041] <<Dispersion medium>> The dispersion medium is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include ketone-based dispersion media such as water, N-methyl-2-pyrrolidone, 2-pyrrolidone, N,N-dimethylacetamide, and cyclohexanone; ester-based dispersion media such as butyl acetate; aromatic dispersion media such as paracymene, xylene, and mesitylene; alcohol-based dispersion media such as 2-n-butoxymethanol, 2-dimethylethanol, ethylene glycol, and propylene glycol; and olefin-based solvents such as tetradecane and dodecane. These may be used alone or in combination of two or more.

[0042] When a sulfide solid electrolyte is contained as another component, a low-polarity solvent that does not have a hydroxyl group, a carboxyl group, etc. is preferably used in order to suppress the decomposition reaction of the sulfide solid electrolyte. Among these, an ester-based compound is preferred from the viewpoint of improving dispersibility.

[0043] <<Dispersant>> The dispersant is not particularly limited and can be appropriately selected depending on the purpose, as long as it is capable of improving the dispersibility of the active material and other particulate materials in the liquid composition for forming an electrode mixture layer. Examples include polymer dispersants such as carboxymethyl cellulose, polyethylene, polyethylene oxide, polypropylene oxide, polycarboxylic acid, naphthalene sulfonic 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.

[0044] <<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.

[0045] 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, more preferably 8% by mass or less, and is preferably 1% by mass or more. A content of the conductive additive relative to the active material of 10% by mass or less is preferable because the stability of the liquid composition for forming an electrode mixture layer is improved, and a content of the conductive additive relative to the active material of 8% by mass or less is preferable because the stability of the liquid composition for forming an electrode mixture layer is further improved. If the content of the conductive additive relative to the active material is 1% by mass or more, the effect of improving the conductivity of the electrode mixture layer is preferably observed.

[0046] <<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.

[0047] 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.

[0048] 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.

[0049] 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.). LiA 1 ON(A 1 is at least one selected from Si, B, Ge, Al, C, Ga, etc.) can also be preferably used.

[0050] Sulfide solid electrolytes can be roughly divided into, for example, crystalline sulfide solid electrolytes and glassy sulfide solid electrolytes.

[0051] 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).

[0052] 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.

[0053] <<Other ingredients>> The other components are not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include dispersants, solid electrolytes, dispersion media, surfactants, pH adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, antireducing agents, evaporation promoters, chelating agents, thickeners, and ionic liquids.

[0054] [viscosity] The viscosity of the electrode mixture layer-forming liquid composition is preferably 20 mPa·s or more, and more preferably 40 mPa·s or more, from the viewpoint of suppressing flattening (a decrease in h1 / h2) due to the weight of the electrode mixture layer-forming liquid composition after it has landed on the substrate. Note that "flattening" in this specification refers to a state in which the electrode mixture layer-forming liquid composition applied as droplets coalesces with adjacent droplets, resulting in a constant film thickness. The viscosity of the electrode mixture layer-forming liquid composition is preferably 150 mPa·s or less, more preferably 100 mPa·s or less, and even more preferably 70 mPa·s or less, from the viewpoint of eliminating a film interface due to coalescence of droplets or liquid columns formed by the electrode mixture layer-forming liquid composition and improving film strength.

[0055] 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.). The viscosity of the electrode mixture layer forming liquid composition is measured at a temperature of 25° C. and a rotation speed of 50 rpm.

[0056] [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 unevenness due to drying.In addition, productivity is improved by shortening the required drying time, reducing the environmental load, and resulting in cost savings.

[0057] 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.

[0058] 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; 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. Solids concentration = {total solids (parts by mass) / (total solids (parts by mass) + dispersion medium (parts by mass) + water (parts by mass))}×100(%)...Formula

[0059] 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.).

[0060] [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.

[0061] <Electrode mixture layer-forming liquid composition drying step and electrode mixture layer-forming liquid composition drying means> 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.

[0062] The means for drying the electrode mixture layer-forming liquid composition is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a NEO hot plate (manufactured by AS ONE Co., Ltd.).

[0063] The various conditions in the drying process of the liquid composition for forming an electrode composite layer are not particularly limited and can be selected appropriately depending on the purpose. For example, the drying time can be shortened by setting the temperature as high as possible within the heat resistance temperature of the electrode material.

[0064] Although an electrode having a desired shape can be formed by alternately repeating the electrode mixture layer-forming liquid composition application step and the electrode mixture layer-forming liquid composition drying step, from the viewpoint of achieving good binding properties, it is preferable to perform the electrode mixture layer-forming liquid composition drying step only once. The reason for the good binding properties is not clear, but it is presumed that the multiple electrode mixture layer-forming liquid composition application steps result in the generation of interfaces within the electrode, which reduces film strength and inhibits the formation of electron / ion conduction paths.

[0065] <Other steps and other means> The other steps are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include 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.

[0066] The pressing step is a step of further pressing the electrode obtained by the electrode manufacturing method. The pressing means is a means for further pressing the electrode obtained by the electrode manufacturing method.

[0067] During the pressing process, the convex portions are pressed strongly to form a high volume density, while the concave portions are pressed weakly to form a low volume density, resulting in an electrode mixture layer with a periodic sparse / dense structure. This can be confirmed by SEM observation. Therefore, even after pressing, the electrolyte permeability into the electrode mixture layer is maintained in a form converted from the periodic uneven structure on the surface of the electrode mixture layer into a periodic porosity difference inside the electrode mixture layer. Because the average volume density of the electrode mixture layer is increased, an electrode with excellent volumetric energy density is obtained. Furthermore, the electronic resistance is reduced, resulting in improved rate characteristics.

[0068] The pressing means is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a 7-ton hydraulic roll press (manufactured by Thank Metal Co., Ltd.). The conditions for pressing are not particularly limited and can be selected appropriately depending on the purpose. For example, the film thickness that will result in the desired basis weight can be calculated backwards, and the press gap can be set to that value.

[0069] 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.

[0070] [Figure 4A] FIG. 4A is a schematic cross-sectional view showing an electrode obtained by a method for producing an electrode according to one embodiment of the present invention. As shown in FIG. 4A, the electrode has a substrate 1 and an electrode mixture layer 2 provided on the substrate 1. The electrode mixture layer 2 has a periodic electrode unevenness structure at least in a cross section in one direction perpendicular to the thickness direction. The periodic electrode unevenness structure has, in the cross section in the one direction, a plurality of convex portions 201 and a plurality of concave portions 202 located between adjacent convex portions 201.

[0071] In this specification, one period T in the electrode concave-convex periodic structure is defined as the distance from the apex of one convex portion to the apex of an adjacent convex portion, or the distance from the apex of one concave portion to the apex of an adjacent concave portion.

[0072] [Figure 4B] The mechanism by which the periodic electrode uneven structure is formed on the electrode obtained by the electrode manufacturing method of the present invention will be described with reference to FIG. 4B. FIG. 4B is a schematic cross-sectional view for explaining the mechanism by which a periodic electrode uneven structure is formed in an electrode obtained by a manufacturing method for an electrode according to one embodiment of the present invention. 4B(a) is a schematic cross-sectional view showing the state immediately after the electrode mixture layer forming liquid composition 203 is applied onto the substrate 1. The electrode mixture layer forming liquid composition 203 applied onto the substrate 1 gradually spreads (levels) over the substrate and coalesces with adjacent droplets, and the regions resulting from the coalescence of the droplets form recesses, and the regions directly below the droplet ejection positions form protrusions.

[0073] In the electrode obtained by the electrode manufacturing method of the present invention, the ratio (h1 / h2) of the height h1 (μm) of the convex portions of the electrode mixture layer to the height h2 (μm) of the concave portions of the electrode mixture layer is 0.71 or more and 0.95 or less. When the ratio (h1 / h2) is 0.71 or more, micro-short circuits at the tips of the projections are suppressed and peel strength is improved, thereby eliminating problems such as short circuits during stacking or charge / discharge. When the ratio (h1 / h2) is 0.95 or less, the difference in surface roughness is large and a sufficient contact area is obtained, which increases the absorption surface of the electrolyte and improves the transport into the electrolyte phase, resulting in an electrode with excellent rate characteristics.

[0074] When the electrode mixture layer is pressed, the porosity of the convex portions becomes lower than that of the concave portions, resulting in a structure in which the porosity changes periodically. Areas with high porosity have high electrolyte permeability and therefore high ionic conductivity, while areas with low porosity have smaller interparticle distances in the conductive additive, resulting in high electronic conductivity. A ratio (h1 / h2) between 0.85 and 1 can be expected to provide particularly effective improvements in rate characteristics.

[0075] The method for measuring the heights of the convex and concave portions of the electrode mixture layer is not particularly limited and can be appropriately selected depending on the purpose. An example is shown below. Observation is performed using a laser microscope VK-X3000 (manufactured by KEYENCE) equipped with a white light interferometer to obtain a cross-sectional unevenness profile, and heights h1 and h2 are calculated.

[0076] Volume Density In the electrode obtained by the electrode manufacturing method, there is no particular limitation on the volume density and it can be selected appropriately depending on the purpose. In the case of the positive electrode, from the viewpoint of forming a conductive path, it is preferable that the volume density is 2 g / cm. 3 More than 3g / cm is preferable. 3 More preferably, from the viewpoint of forming an ion conductive path, 4 g / cm 3 Less than 3.5 g / cm is preferred 3 The following is more preferred: For the negative electrode, from the viewpoint of forming a conductive path, 2 g / cm 3 More than 2.5g / cm is preferable. 3 More preferably, from the viewpoint of forming an ion conductive path, 4 g / cm 3 Less than 3.5 g / cm is preferred 3 The following is more preferred:

[0077] The method for measuring the volume density is not particularly limited and can be appropriately selected depending on the purpose. An example is shown below. Several electrodes are punched out using a punch with a diameter of approximately 10 to 16 mm, and the weight of each substrate is measured. The weight of the substrate is determined by measuring the weight of the punched-out substrate alone in advance and subtracting this value. The cross section of the punched electrode is measured using a laser microscope VK-X3000 (manufactured by KEYENCE) equipped with a white light interferometer, and the average film thickness is calculated. The volume density is calculated by dividing the electrode weight by (average film thickness x surface area of ​​the electrode).

[0078] [Figures 5A-5B] FIG. 5A is a schematic cross-sectional view showing an electrode obtained by a method for producing an electrode according to one embodiment of the present invention. The electrode mixture layer 2 may have an opening 206 as shown in FIG. 5A. The number of openings 206 is preferably one or more, and more preferably two or more. The opening 206 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 206 may be hollow or filled with material 207. When opening 206 is filled with material 207, material 207 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 207 is preferably a material having a solid electrolyte from the viewpoint of improving ion conductivity. The electrode mixture layer having the openings 206 can be suitably produced by using inkjet as an electrode mixture layer forming means, since application control is easy.

[0079] FIG. 5B is a schematic cross-sectional view showing an electrode obtained by a method for producing an electrode according to another embodiment of the present invention. As shown in FIG. 5B, the electrode mixture layer may include an adhesive layer 208 between the substrate 1 and the electrode mixture layer 2, the adhesive layer 208 containing a metal that alloys with lithium.

[0080] [FIG. 6: An embodiment in which an electrode mixture layer is formed by directly applying an electrode mixture layer-forming liquid composition to a substrate] FIG. 6 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 the electrode mixture layer-forming liquid composition 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.

[0081] -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 to form an electrode composite layer on the printing substrate 34, a storage container 31b that stores the electrode composite layer forming liquid composition, 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.

[0082] -Heating section 200- 6, 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.

[0083] [Figure 7] FIG. 7 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.

[0084] [Figure 8] FIG. 8 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. 8. Here, the feed roller 304 and the take-up roller 305 rotate counterclockwise in FIG. 8, and the substrate 211 is transported from right to left in FIG. 8. Then, droplets of the electrode mixture layer-forming liquid composition 12A are ejected onto the substrates 211 that are being transported sequentially, in the same manner as in FIG. 7, from a liquid ejection head 306 installed above the substrate 211 between the feed roller 304 and the take-up roller 305. 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.

[0085] [Figure 9] FIG. 9 is a schematic diagram showing a modified example of an electrode manufacturing apparatus according to one embodiment of the present invention. 9, 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, the liquid ejection apparatus may have tubes 308A and 308B, valves 311A, 311B, 312A, 312B, valves 314A and 314B, and pumps 310A and 310B.

[0086] [FIG. 10: An embodiment in which an electrode mixture layer is formed by indirectly applying an electrode mixture layer-forming liquid composition to a substrate] Fig. 10 is a structural 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. 10 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 .

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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 .

[0092] 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.

[0093] [Figure 11] 11 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. 11 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.

[0094] 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.

[0095] 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. 11. 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.

[0096] [Figures 12-13] Fig. 12 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 Fig. 13 is a schematic diagram showing another 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. 12 and 13, 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. 12 shows an electrode mixture layer in which convex regions 13 and concave regions 14 are periodically formed and which is flat in the Y direction. FIG. 13 shows an electrode mixture layer in which convex regions 15 and concave regions 16 are periodically formed in the Y direction and which is flat in the X direction.

[0097] (electrochemical element) The electrochemical device according to the present invention has an electrode obtained by the electrode manufacturing method 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. As a method for producing an electrochemical element, any known method can be appropriately selected, provided that the electrode is obtained by the electrode production method of the present invention.

[0098] <Electrolytes> The electrolyte may be an aqueous electrolyte solution or a non-aqueous electrolyte solution.

[0099] -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.

[0100] -Non-aqueous electrolyte- As the non-aqueous electrolyte, a non-aqueous electrolytic solution, a solid electrolyte, or a gel electrolyte can be used.

[0101] --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.

[0102] Examples of the chain carbonate include dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC).

[0103] 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.

[0104] Examples of cyclic carbonates include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), and vinylene carbonate (VC).

[0105] 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.

[0106] Examples of cyclic esters include γ-butyrolactone (γBL), 2-methyl-γ-butyrolactone, acetyl-γ-butyrolactone, and γ-valerolactone.

[0107] 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).

[0108] Examples of cyclic ethers include tetrahydrofuran, alkyltetrahydrofuran, alkoxytetrahydrofuran, dialkoxytetrahydrofuran, 1,3-dioxolane, alkyl-1,3-dioxolane, and 1,4-dioxolane.

[0109] 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.

[0110] The electrolyte salt in the non-aqueous electrolyte solution is not particularly limited as long as it has high ionic conductivity and can be dissolved 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 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.

[0111] 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.

[0112] --Solid electrolyte-- As the solid electrolyte, the same as those described in the <<Solid Electrolyte>> section can be used.

[0113] --Gel electrolyte-- The gel electrolyte is not particularly limited as long as it exhibits ionic 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.

[0114] 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 combination of a gel electrolyte precursor material, such as polyethylene oxide or polypropylene oxide having acrylate groups at both ends, and a solution in which an ionic liquid or a lithium salt is dissolved may be used.

[0115] <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.

[0116] <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.

[0117] 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.

[0118] 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.

[0119] [Figure 14] FIG. 14 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 layer 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.

[0120] [Figure 15] FIG. 15 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. 14. 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.

[0121] (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 according to the present invention, and an element forming means for manufacturing an electrochemical element using the electrode, and further comprises other means as necessary. The method for manufacturing an electrochemical device according to the present invention includes an electrode manufacturing step of manufacturing an electrode by the electrode manufacturing method of the present invention, and an element manufacturing step of manufacturing an electrochemical device using the electrode, and may further include other steps as necessary.

[0122] <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).

[0123] <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.

[0124] [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.

[0125] [Figure 16] FIG. 16 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.

[0126] 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.

[0127] 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]

[0128] 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".

[0129] <Preparation of Liquid Compositions 1 to 18 for Forming Electrode Mixture Layer> The 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 for 2 minutes using an ultrasonic homogenizer (manufactured by Nippon Seiki Co., Ltd.), thereby obtaining liquid compositions 1 to 18 for forming an electrode composite layer. The details of each component are as follows: -Active material- Gr: Artificial graphite (manufactured by Hitachi Chemical Co., Ltd.) SiO: Silicon oxide (Aldrich) NCM: Lithium nickel cobalt manganese oxide (average primary particle size 3.5 μm, manufactured by Toshima Manufacturing Co., Ltd.) -Binder- SBR: Styrene-butadiene rubber (manufactured by Nippon Zeon Co., Ltd.) P(DEAmEMA-BMA): Poly(diethylaminoethyl methacrylate-butyl methacrylate) copolymer -Conductive additive- AB: Acetylene black (Denka Black, manufactured by Denka Co., Ltd.) SWCNT: (Oxial) -Dispersant- CMC: Carboxymethyl cellulose (Dai-ichi Kogyo Seiyaku Co., Ltd.) BYK-ET3000: (Manufactured by BYK) -Dispersion medium- NMP: N-methyl-2-pyrrolidone (Tokyo Chemical Industry Co., Ltd.)

[0130] 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 the addition was completed, the mixture was stirred at 80°C for 8 hours and allowed to cool to room temperature. The reaction solution was then added dropwise to methanol, and the precipitate was recovered by decantation and dried in vacuo to synthesize a copolymer with a weight-average molecular weight of 113,000.

[0131] [Table 1]

[0132] <Electrode manufacturing example 1> A valve-type nozzle disclosed in a patent document (Patent 7271956) was attached to an inkjet discharge evaluation device (device name: EV2500, manufactured by Ricoh Co., Ltd.), and the liquid composition for forming an electrode mixture layer was applied to a substrate at the application cycle, nozzle diameter, and number of passes (number of times for the electrode mixture layer forming liquid composition application step and the electrode mixture layer forming liquid composition drying step) shown in Table 2. After application, the electrode was obtained by drying on a hot plate. Note that the valve-type nozzle in the inkjet discharge evaluation device was positioned perpendicular to the substrate transport direction. In addition, when the liquid composition for forming an electrode mixture layer is used for a negative electrode, the substrate is 15 μm copper foil, the drying temperature is 80° C., and the coating weight is 7 mg / cm 2 For positive electrode applications, the substrate was aluminum foil, the drying temperature was 120°C, and the coating weight was 20 mg / cm. 2 It was decided.

[0133] <Electrode Manufacturing Examples 2 to 10> An electrode was obtained in the same manner as in Electrode Production Example 1, except that the conditions were changed as shown in Table 2.

[0134] <Electrode Manufacturing Example 11> Electrode Manufacturing Example 11 is an example in which an electrode having a concave-convex structure is manufactured by pressing a flat electrode with a concave-convex mold, with reference to Patent Document 1. The electrode mixture layer-forming liquid composition was applied to the substrate by die coating, and then dried to form a flat electrode mixture layer. The electrode mixture layer was then pressed using a concave-convex mold with a periodic pitch of 1.27 μm to obtain an electrode having a concave-convex structure. In addition, when the liquid composition for forming an electrode mixture layer is used for a negative electrode, the substrate is 15 μm copper foil, the drying temperature is 80° C., and the coating weight is 7 mg / cm 2 For positive electrode applications, the substrate was aluminum foil, the drying temperature was 120°C, and the coating weight was 20 mg / cm. 2 It was decided.

[0135] <Electrode Manufacturing Example 12> Electrode Manufacturing Example 12 is a manufacturing example in which, with reference to Patent Document 2, an electrode having a concave-convex structure is obtained by providing a second layer electrode having a concave-convex structure on a flat first layer electrode. To apply the electrode mixture layer-forming liquid composition to the substrate, the electrode mixture layer-forming liquid composition was applied by die coating and then dried to form a flat electrode mixture layer. Next, a second electrode layer having an uneven structure was applied onto the obtained first electrode layer using the same procedure as in Electrode Production Example 1. In addition, when the liquid composition for forming an electrode mixture layer is used for a negative electrode, the substrate is 15 μm copper foil, the drying temperature is 80° C., and the coating weight is 7 mg / cm 2 For positive electrode applications, the substrate was aluminum foil, the drying temperature was 120°C, and the coating weight was 20 mg / cm. 2 It was decided.

[0136] <Electrode Manufacturing Example 13> Electrode Production Example 13 is a production example in which an electrode having a concave-convex structure is obtained using an inkjet printing device, with reference to Patent Document 3. Using an inkjet device (device name: EV2500, nozzle name: MH2810-F, manufactured by Ricoh Co., Ltd.), the liquid composition for forming the electrode mixture layer was applied to a heated substrate and dried. This process was repeated for a total of 10 passes, and the amount applied locally was changed for each nozzle, thereby obtaining an electrode with a textured structure. In addition, when the liquid composition for forming an electrode mixture layer is used for a negative electrode, the substrate is 15 μm copper foil, the drying temperature is 80° C., and the coating weight is 7 mg / cm 2 For positive electrode applications, the substrate was aluminum foil, the drying temperature was 120°C, and the coating weight was 20 mg / cm. 2 It was decided.

[0137] [Table 2]

[0138] (Examples 1 to 35 and Comparative Examples 1 to 4)

[0139] Electrodes of each Example and Comparative Example were produced using the combinations shown in Tables 3 and 4 of each liquid composition for forming an electrode mixture layer and each Production Example. The resulting electrodes were checked for the presence or absence of an electrode irregularity periodic structure, and were subjected to measurement of the electrode irregularity period, irregularity height, volume density, peel strength, and rate characteristic. The results are shown in Tables 3 and 4. When roll pressing is performed, the height of the unevenness after pressing is also measured. Furthermore, the measurement of the volume density, the evaluation of the peel strength, and the evaluation of the rate characteristics are performed after pressing. The roll press treatment was carried out using a 7-ton hydraulic roll press (manufactured by Thank Metal Co., Ltd.), and the film thickness that would result in the volume density shown in Tables 3 and 4 was calculated backward, and this value was set as the press gap.

[0140] [Checking for the presence of periodic uneven structures and measuring their period] Observation was performed using a laser microscope VK-X3000 (manufactured by KEYENCE) equipped with a white light interferometer to obtain a cross-sectional unevenness profile perpendicular to the electrode transport direction, and the average period of the electrode unevenness was measured. The average period was calculated by selecting five consecutive points based on the apex of a convex portion in one period arbitrarily selected near the center of the electrode in the obtained concavo-convex profile, and multiplying the average distance between each point by 2. The results are shown in Tables 3 and 4.

[0141] [Measurement of unevenness height] The height h1 of the recesses and the height h2 of the protrusions were calculated from the cross-sectional unevenness profile obtained by measuring the period. The height h1 of the recesses and the height h2 of the protrusions were calculated by selecting five consecutive points based on an arbitrarily selected minimum or maximum point in one period in the obtained unevenness profile, and averaging them. The results are shown in Tables 3 and 4.

[0142] [Volume density measurement] Three pieces of each electrode were punched out with a Φ16 mm punch, and the weight of each substrate was measured. The average film thickness was calculated from the value obtained from the measurement of the irregularity height. The weight of the electrode excluding the substrate was calculated by subtracting the weight of the substrate punched out with the Φ16 mm punch, and the volume density was calculated by dividing the weight of the electrode excluding the substrate by (average film thickness × surface area of ​​the electrode). The results are shown in Tables 3 and 4.

[0143] [Evaluation of peel strength] A 10 mm wide Kapton tape with a 30 mm adhesive length was attached to the electrode composite layer, and the peel strength F (N / m) was measured using a benchtop tensile tester (EZ-SX 100N, manufactured by Shimadzu Corporation). The peel angle was 90° and the peel speed was 30 mm / min. The evaluation was performed three times under the same conditions, and the average value was calculated. The results are shown in Tables 3 and 4.

[0144] [Rate characteristic evaluation] The rate characteristics of the positive electrode or negative electrode were evaluated using a charge / discharge measuring device (TOSCAT3001, manufactured by Toyo Systems Co., Ltd.). The prepared electrode was punched into a circle with a diameter of 16 mm, and then placed in a coin can. The 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%) + fluoroethylene (FEC) 10%) (manufactured by Kishida Chemical Co., Ltd.)), and a 200 μm thick lithium foil (manufactured by Honjo Metal Co., Ltd.) as a counter electrode were placed therein to prepare an electrochemical element. When the evaluation target was the positive electrode, the fabricated electrochemical element was charged at room temperature (25°C) at a constant current of 0.2C, 1.0C, 2.0C, 3.0C, 4.0C, and 5.0C at C rates up to 4.2V, and then discharged at a constant current down to 3.0V to measure the charge / discharge capacity. Furthermore, the rate characteristics were evaluated using the ratio of the discharge capacity at 0.2C to the discharge capacity at 5.0C 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 constant current charging was limited to 2.0 V and constant current discharging was limited to 0.05 V. Note that the C rate refers to the rate of charging and discharging, and in the case of constant current charge / discharge measurements, the magnitude of the current that fully charges (or discharges) the theoretical capacity of the battery in one hour is defined as 1.0 C. For comparison, an electrode having a flat positive electrode composite layer or a flat negative electrode composite layer was prepared by applying a liquid composition for forming an electrode composite layer having a similar composition to a substrate using an applicator and drying it. The capacity retention ratio was calculated when the rate characteristic of this electrode was set to 100. A rate characteristic (capacity retention) ratio exceeding 110 was considered to be acceptable. Evaluation under the same conditions was performed three times, and the average value was calculated. The results are shown in Tables 3 and 4.

[0145] [Table 3]

[0146] [Table 4]

[0147] The results in Tables 3 and 4 show that electrodes manufactured by a method for manufacturing an electrode having an electrode composite layer with a periodic uneven structure on its surface, the method including a liquid composition application step in which an electrode composite layer forming liquid composition containing an active material and a dispersion medium is applied onto the substrate at an application period of 0.28 mm to 1.7 mm using a liquid ejection device having multiple nozzle holes arranged in a direction parallel to the substrate surface, or electrodes having a substrate and an electrode composite layer with a periodic uneven structure on its surface on the substrate, in which the ratio (h1 / h2) of the height h1 (μm) of the recesses of the electrode composite layer to the height h2 (μm) of the protrusions of the electrode composite layer is 0.71 to 0.95, have good rate characteristics and binding properties. Furthermore, from the viewpoint of facilitating the formation of a periodic uneven electrode structure, it is clear that excellent rate characteristics are obtained when the viscosity of the electrode mixture layer-forming liquid composition is 20 mPa·s or higher, particularly 40 mPa·s or higher. Although the reason for this is unclear, it is presumed that unevenness in film thickness and composition is suppressed as a result of the suppression of flow due to thermal convection during the appropriate drying process of the electrode mixture layer-forming liquid composition. Furthermore, from the viewpoint of ease of coalescence, it can be seen that particularly excellent rate characteristics and binding properties are obtained when the viscosity of the electrode mixture layer forming liquid composition is 150 mPa s or less, particularly 100 mPa s or less. Although the reason for this is not clear, it is presumed that this is due to the fact that the electrode mixture layer forming liquid compositions dispensed from each nozzle are mixed homogeneously when coalesced. Furthermore, by further pressing an electrode having a periodic uneven electrode structure and converting the uneven structure on the electrode surface into a void density distribution within the electrode, the volume density increases, and it is found that an electrode that is particularly excellent in terms of volumetric energy density can be obtained. It was also found that good battery characteristics were obtained when a manufacturing method was used to form a periodic uneven structure through multiple electrode composite layer-forming liquid composition application steps and electrode composite layer-forming liquid composition drying steps. However, compared to a single-pass printing method, the effect was limited. Furthermore, the adhesion was poor. While the cause is unclear, it is presumed that the formation of interfaces inside the electrode due to multiple application steps led to a decrease in film strength and the inhibition of the formation of electron / ion conduction paths.

[0148] The results of Comparative Examples 1 to 3 show that good rate characteristics are not obtained when the application period is outside the range of the present invention or when the ratio (h1 / h2) is outside the range of the present invention. Although the reason for this is unclear, it is presumed that when the application period exceeds the upper limit, the intervals between the alternating appearance of electron-conductive path-dominated and ion-conductive path-dominated portions in the electrode mixture layer become longer, resulting in a loss of compatibility between electron-conductive path and ion-conductive path. Furthermore, when the application period exceeds the lower limit, adjacent electrode mixture layer-forming liquid compositions immediately coalesce during the electrode mixture layer-forming liquid composition application step, causing the ratio (h1 / h2) to approach 1, i.e., making it difficult to obtain a periodic electrode uneven structure. The results of Comparative Example 4 show that when a flat electrode is formed using a die coater and then an electrode having a periodic uneven structure is produced using a mold press with an uneven structure, good adhesion cannot be obtained. The reason for this is unclear, but it is presumed that, in contrast to the electrode manufacturing method of the present invention, the volume density (porosity) of the convex parts is high, which reduces the film strength of the convex parts.

[0149] The present invention includes, for example, the following aspects. <1> A method for manufacturing an electrode having an electrode mixture layer having a periodic uneven structure on a surface thereof, comprising: The method for manufacturing an electrode is characterized by including a step of applying a liquid composition for forming an electrode composite layer, using a liquid ejection device having a plurality of nozzle holes arranged in a direction parallel to the surface of the substrate, to apply a liquid composition for forming an electrode composite layer, which contains an active material and a dispersion medium, onto the substrate at an application period of 0.28 mm or more and 1.7 mm or less. <2> the liquid ejection device is an inkjet device, <1> 2. A method for producing the electrode according to claim 1. <3> The inkjet device is a valve type. <2> 2. A method for producing the electrode according to claim 1. <4> The viscosity of the liquid composition for forming an electrode mixture layer is 20 mPa·s or more and 150 mPa·s or less. <1> from <3> 10. A method for producing an electrode according to any one of the preceding claims. <5> <1> from <4> 1. An electrode characterized by being manufactured by the electrode manufacturing method described in any one of . <6> a substrate; an electrode mixture layer having a periodic uneven structure on the surface thereof on the substrate; a ratio (h1 / h2) of a height h1 (μm) of a concave portion of the electrode mixture layer to a height h2 (μm) of a convex portion of the electrode mixture layer is 0.71 or more and 0.95 or less; <5> The electrode is described in <7> It is further manufactured by pressing <5> or <6> The electrode is described in

[0150] <1> from <4> A method for producing an electrode according to any one of the preceding claims, and <5> from <7> The electrode described in any one of the above items can solve the various problems in the prior art and achieve the object of the present invention. [Explanation of symbols]

[0151] 1 Base 2 Electrode composite layer 12A Liquid composition for forming electrode composite material layer 100 printing department 200 Heating section 500 Electrode manufacturing equipment [Prior art documents] [Patent documents]

[0152] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-138619 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-051209 [Patent Document 3] Japanese Patent Application Publication No. 2023-138315 [Non-patent literature]

[0153] [Non-Patent Document 1] Adv.Energy Mater.2016,6(18),1600856 [Non-patent document 2] Electrochimica Acta,79,(2012),218-222

Claims

1. A method for manufacturing an electrode having an electrode mixture layer having a periodic uneven structure on a surface thereof, comprising: The method for manufacturing an electrode includes a liquid composition application step of applying an electrode composite layer-forming liquid composition containing an active material and a dispersion medium onto the substrate at an application period of 0.28 mm or more and 1.7 mm or less, using a liquid ejection device having a plurality of nozzle holes arranged in a direction parallel to a substrate surface.

2. The method for manufacturing an electrode according to claim 1 , wherein the liquid ejection device is an inkjet device.

3. The electrode manufacturing method according to claim 2 , wherein the ink-jet device is a valve type.

4. The method for manufacturing an electrode according to claim 1 , wherein the viscosity of the electrode mixture layer forming liquid composition is 20 mPa·s or more and 150 mPa·s or less.

5. An electrode manufactured by the method for manufacturing an electrode according to any one of claims 1 to 4.

6. a substrate; an electrode mixture layer having a periodic uneven structure on the surface thereof on the substrate; 6. The electrode according to claim 5, wherein a ratio (h1 / h2) of a height h1 (μm) of a concave portion of the electrode mixture layer to a height h2 (μm) of a convex portion of the electrode mixture layer is 0.71 or more and 0.95 or less.

7. 7. The electrode of claim 6 further manufactured by pressing.

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