Liquid composition for forming an insulating layer, method for manufacturing an electrode, and liquid composition for inkjet printing

Abstract

To provide a liquid composition for forming an insulating layer that uses N-methyl-2-pyrrolidone as the main solvent and can form an insulating film with excellent continuous discharge properties, coating properties, and peel strength. [Solution] A liquid composition for forming an insulating layer, comprising insulating inorganic particles, a dispersant having a carboxyl group or an acid anhydride group, a binder, and a surfactant, with N-methyl-2-pyrrolidone as the main solvent, wherein the weight-average molecular weight of the binder is 25,000 or more and 80,000 or less, the dynamic surface tension at 25°C is less than 40 mN / m, and the static surface tension at 25°C is 20 mN / m or more and 32 mN / m or less.

Description

[Technical Field]

[0001] The present invention relates to a liquid composition for forming an insulating layer, a method for manufacturing an electrode, and a liquid composition for inkjet printing. [Background technology]

[0002] In energy storage devices, techniques for providing an insulating layer have been proposed. For example, to suppress the rise in battery temperature after an internal short circuit due to foreign matter contamination, a non-aqueous electrolyte secondary battery has been proposed that has a protective layer covering the boundary between the exposed portion of the current collector (where the active material layer is not formed) and the active material layer, and the protective layer contains a curable resin and inorganic particles (see, for example, Patent Document 1). Furthermore, electrochemical elements or electrodes equipped with an insulating layer containing a compound having hydroxyl groups at its ends as a binder, or a compound having carboxyl groups or acid anhydrides as a dispersant, have been proposed for purposes such as improving the strength of the insulating layer, maintaining battery characteristics, and ensuring good stability (see, for example, Patent Documents 2-3).

[0003] In coating insulating particles, when forming a protective film (hereinafter referred to as an edge coat film) that covers the boundary between the exposed portion of the current collector and the active material layer, inkjet printing is preferred as a means of applying the insulating layer-forming liquid composition with good positional accuracy, thinly, and uniformly.

[0004] When forming the positive electrode active material as an composite layer on the positive electrode current collector, high-energy-density high-nickel lithium composite metal oxides such as NCM (nickel-cobalt-manganese) and NCA (nickel-cobalt-aluminum) are often used as the positive electrode material, and N-methyl-2-pyrrolidone (hereinafter also referred to as NMP) is sometimes used as a solvent in slurries, etc. [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention aims to provide a liquid composition for forming an insulating layer that, while using N-methyl-2-pyrrolidone as the main solvent, can form an insulating film with excellent continuous discharge properties, coating properties, and peel strength. [Means for solving the problem]

[0006] The present invention provides a liquid composition for forming an insulating layer as a means of solving the problem, comprising insulating inorganic particles, a dispersant having a carboxyl group or an acid anhydride group, a binder, and a surfactant, with N-methyl-2-pyrrolidone as the main solvent, wherein the weight-average molecular weight of the binder is 25,000 or more and 80,000 or less, the dynamic surface tension at 25°C is less than 40 mN / m, and the static surface tension at 25°C is 20 mN / m or more and 32 mN / m or less. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a liquid composition for forming an insulating layer that can form an insulating film with excellent continuous discharge properties, coating properties, and peel strength, while using N-methyl-2-pyrrolidone as the main solvent. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic cross-sectional view showing an example of the electrode configuration related to the present invention. [Figure 2A] Figure 2A is a schematic cross-sectional view showing another example of the electrode configuration related to the present invention. [Figure 2B] Figure 2B is a schematic cross-sectional view showing another example of the electrode configuration related to the present invention. [Figure 3A] Figure 3A is a schematic cross-sectional view showing another example of the electrode configuration related to the present invention. [Figure 3B] Figure 3B is a schematic cross-sectional view showing another example of the electrode configuration related to the present invention. [Modes for carrying out the invention]

[0009] (Liquid composition for forming an insulating layer) The liquid composition for forming an insulating layer of the present invention contains insulating inorganic particles, a dispersant having a carboxyl group or an acid anhydride group, a binder, a surfactant, and N-methyl-2-pyrrolidone, and may optionally contain other nonvolatile components.

[0010] In this specification, "liquid composition for forming an insulating layer" may be simply referred to as "insulating film ink." In this specification, "dispersant having a carboxyl group or an acid anhydride group" may be simply referred to as "dispersant." In this specification, "binder" may be referred to as "binder for forming an insulating layer." In this specification, "main solvent" refers to the solvent used with the intention of dispersing the insulating film ink, and does not consider water mixed in as an impurity or trace amounts of solvent species mixed in additives. Specifically, the main solvent is defined as a substance containing 90% or more of the non-solid components, and water mixed in the ink is not considered to be included in the composition if it is 3.0% by mass or less of the total insulating film ink, and solvent species other than the main solvent and water are not considered to be included in the composition if they are 1.0% by mass or less of the total insulating film ink for each component.

[0011] <Insulating inorganic particles> In this specification, "insulating properties" means that the volume resistivity is 10 8 This indicates that the resistivity is Ω·cm or greater. In other words, insulating inorganic particles in this invention have a volume resistivity of 10 8 This refers to inorganic particles with a size of Ω·cm or greater.

[0012] As insulating inorganic particles, the volume resistivity is 10 8 As long as the density is Ω·cm or greater, there are no particular restrictions and it can be appropriately selected according to the purpose. Examples include aluminum oxide (alumina), boehmite, silica, aluminum nitride, silicon nitride, cordierite, thyacron, mullite, stearite, yttria, zirconia, and silicon carbide. Among these, inorganic oxides are preferred, aluminum oxide and boehmite are more preferred, and α-alumina is even more preferred.

[0013] α-Alumina is known to function as a scavenger for "junk" chemical species, i.e., chemical species that can cause capacity fade in a lithium-ion secondary battery. Further, since alumina particles have good wettability and affinity for the electrolyte, the cycle performance of the lithium-ion secondary battery is improved. By using α-alumina as the insulating inorganic particles, in the liquid composition, the redispersibility and the ejection property by inkjet are improved, and in the insulating layer, the heat resistance is improved. These insulating inorganic particles may be used alone or in combination of two or more.

[0014] The shape of the insulating inorganic particles is not particularly limited and can be appropriately selected according to the purpose. For example, rectangular, spherical, elliptical, cylindrical, egg-shaped, dog-bone-shaped, amorphous, etc. can be mentioned. Among these, from the viewpoint of improving the ejection property by inkjet, it is preferable that the aspect ratio of the long side to the short side of the insulating inorganic particles is close to 1.

[0015] The median diameter of the insulating inorganic particles is not particularly limited and can be appropriately selected according to the purpose, but it is preferably 200 nm or more and 1,000 nm or less. When the median diameter of the insulating inorganic particles is 200 nm or more, it is possible to suppress the particles from dancing in the air (generation of mist) during ejection by inkjet. Also, in the insulating layer, it is possible to suppress the adhesion of the insulating inorganic particles on the substrate due to the absence of fine particles. When the median diameter of the insulating inorganic particles is 1,000 nm or less, it is possible to eliminate nozzle clogging during ejection by inkjet, and the ejection property is improved. Also, in the insulating layer, it is suitable because the thickness of the insulating layer is made uniform and homogenized (less unevenness).

[0016] The method for measuring the median diameter of the insulating inorganic particles is not particularly limited and can be appropriately selected according to the purpose. For example, after diluting so that the solid content of the liquid composition becomes 10 mass% or less, it can be measured using a particle size measuring device (nanoSAQLA, manufactured by Otsuka Electronics Co., Ltd.).

[0017] There are no particular restrictions on the content of insulating inorganic particles, and it can be appropriately selected according to the purpose. However, from the viewpoint of ensuring a uniform thickness of the insulating layer after drying, it is preferable that the content be 20% to 50% by mass, more preferably 30% to 49% by mass, and even more preferably 40% to 48% by mass, relative to the total amount of the liquid composition. When the content of insulating inorganic particles is 20% by mass or more relative to the total amount of the liquid composition, it is possible to suppress the leakage from the resulting insulating layer onto the substrate and electrode composite layer. When the content of insulating inorganic particles is 50% by mass or less relative to the total amount of the liquid composition, nozzle clogging during inkjet ejection can be eliminated, and ejection performance is improved. Furthermore, it is preferable because the insulating layer is homogenized.

[0018] As insulating inorganic particles, you may use those that you have synthesized as appropriate, or you may use commercially available ones. Examples of commercially available aluminum oxide as insulating inorganic particles include, by trade name, AKP-15, AKP-20, AKP-30, AKP-50, AKP-53, AKP-700, AKP-3000, AA-03, AA-04, AA-05, AA-07, AA-1.5, AKP-G07, AKP-G15 (all high-purity alumina, manufactured by Sumitomo Chemical Co., Ltd.), TM-DA, TM-DAR, TM-5D (all manufactured by Daimyo Chemical Industry Co., Ltd.), CT-3000LSSG (manufactured by Almatis), LS-502, LS-711CB, SLS-710 (manufactured by Nippon Light Metal Co., Ltd.), SEPal-60, SEPal-70 (manufactured by Alteo).

[0019] <Dispersants having carboxyl groups or acid anhydride groups> The dispersant in the present invention has a carboxyl group or an acid anhydride group. Carboxyl groups have a repulsive effect on dispersant molecules due to steric hindrance. Therefore, by adding a dispersant containing carboxyl groups to a liquid composition, insulating inorganic particles in the liquid composition can be uniformly dispersed as primary particles, and the dispersed state can be maintained without re-aggregation over a long period of time. Acid anhydride groups have excellent compatibility with binders for forming insulating layers, and can reduce thixotropy in the liquid composition. Furthermore, carboxyl groups or acid anhydride groups can improve inkjet ejection performance due to their respective effects. In addition, in the resulting insulating layer, problems such as the dispersant dissolving into the electrolyte, leading to a decrease in output due to increased battery resistance, and a decrease in cycle characteristics can be eliminated.

[0020] There are no particular restrictions on the dispersant having an acid anhydride group, and it can be appropriately selected depending on the purpose. For example, dispersants containing a structural unit represented by general formula (1) can be used.

[0021] [ka] (In general formula (1), * represents a binding site with an adjacent main chain structural unit. n represents an integer.)

[0022] There are no particular restrictions on the dispersant having a carboxyl group, and it can be appropriately selected depending on the purpose. Examples include dispersants containing structural units represented by general formula (2) and dispersants containing structural units represented by general formula (3).

[0023] [ka]

[0024] [ka] (In general formulas (2) and (3), * represents a bonding site with an adjacent main chain structural unit, and M represents an ammonium salt. m and l are integers that may be different.)

[0025] There are no particular restrictions on n in general formula (1), and it can be appropriately selected depending on the purpose. For example, it can be 10 to 500, and preferably 30 to 100. In general formula (2), there are no particular restrictions on m, and it can be appropriately selected depending on the purpose. For example, it can be between 10 and 500, and preferably between 30 and 100. In general formula (3), there are no particular restrictions on l, and it can be appropriately selected depending on the purpose. For example, it can be between 10 and 500, and preferably between 30 and 100.

[0026] There are no particular restrictions on the method for determining whether a dispersant contains structural units represented by general formulas (1) to (3), and a suitable method can be selected depending on the purpose. Examples include nuclear magnetic resonance (NMR) spectrometers and Fourier transform infrared spectroscopy (FT-IR). More specifically, it is possible to determine whether each structural unit is present by scraping off the insulating layer, immersing it in a tetrahydrofuran (THF) solvent, dissolving the resin components, and then performing analysis.

[0027] There are no particular restrictions on the molecular weight of the dispersant, and it can be appropriately selected according to the purpose. For example, the number average molecular weight can be between 1,000 and 100,000. A number average molecular weight of 1,000 or more of the dispersant provides excellent dispersibility between insulating inorganic particles. A number average molecular weight of 100,000 or less of the dispersant provides excellent ejection performance for inkjet printing. There are no particular restrictions on the method of analyzing the molecular weight of the dispersant, and it can be appropriately selected according to the purpose. For example, it can be measured by gel permeation chromatography (GPC, manufactured by Shimadzu Corporation).

[0028] There are no particular restrictions on the dispersant content in the insulating layer, and it can be appropriately selected according to the purpose. However, it is preferably 0.5% to 5% by mass, and more preferably 1% to 3% by mass, relative to the total amount of insulating inorganic particles in the insulating layer. When the dispersant content is 0.5% by mass or more relative to the total amount of insulating inorganic particles in the insulating layer, the dispersion effect of the insulating inorganic particles can be sufficiently obtained, and the dispersed state can be maintained. Consequently, the ejection performance by inkjet can be improved. In addition, since the surface of the insulating inorganic particles is covered in the resulting insulating layer, it is possible to prevent them from falling out of the insulating layer. When the dispersant content is 5% by mass or less relative to the total amount of insulating inorganic particles in the insulating layer, thixotropy can be reduced. In addition, in the resulting insulating layer, problems such as the dispersant dissolving into the electrolyte and affecting battery performance can be eliminated.

[0029] As a dispersant, you may use one that you have synthesized as appropriate, or you may use a commercially available product. Examples of commercially available dispersants include Marialim® AAB-0851, Marialim AFB-1521, Marialim AKM-0531, Marialim AWS-0851, Marialim HKM-50A, Marialim SC-0708A, Marialim SC-0505K, Marialim SC-1015F (all manufactured by NOF Corporation), SN Dispersant 5020, SN Dispersant 5040, SN Dispersant 5468, Nopcospers 5600, Nopcosanto RFA (all manufactured by Sunnopco Corporation), and SCONA® TSPP 10213GB, TSPP 22113GA, TSIN 4013 GC, TSPOE 1002. Examples include GBLL, DISPER® BYK108, BYK-P105 (all manufactured by Big Chemie Co., Ltd.), Isoban®-04, Isoban-06, and Isoban-10 (manufactured by Kuraray Co., Ltd.).

[0030] <Binder> The binder for forming the insulating layer in the present invention preferably has a fluoroethylene group and a vinyl ether group. When the binder for forming the insulating layer contains only fluoroethylene groups, its solubility in the solvent tends to be low, and its thixotropy tends to be high. Furthermore, it is difficult to achieve a viscosity suitable for inkjet printing. Even if the viscosity is reduced by lowering the concentration of solids in the liquid composition, this is unsuitable because it can lead to uneven coating on the substrate or an increase in the relative amount of liquid composition applied. In the present invention, if the binder for forming the insulating layer contains fluoroethylene groups and vinyl ether groups, its solubility in common solvents such as alcohol-based and ether-based solvents is improved, and consequently, its thixotropy decreases, resulting in a liquid composition that can be stably ejected by inkjet printing. Furthermore, in the resulting insulating layer, the inclusion of fluoroethylene groups in the binder for forming the insulating layer can improve battery stability. Thixotropy refers to the property of a fluid in which its viscosity reversibly decreases when a force is applied to it.

[0031] There are no particular limitations on the method for determining whether the binder for forming the insulating layer in the present invention has fluoroethylene groups and vinyl ether groups, and a suitable method can be selected depending on the purpose. Examples include nuclear magnetic resonance (NMR) spectrometers and Fourier transform infrared spectroscopy (FT-IR). More specifically, the functional groups can be identified by scraping off the insulating layer, immersing it in a tetrahydrofuran (THF) solvent or the like to dissolve the resin components, and then performing an analysis.

[0032] The weight-average molecular weight (Mw) of the binder for forming the insulating layer in this invention is 25,000 or more and 80,000 or less. If the weight-average molecular weight (Mw) of the binder for forming the insulating layer is 25,000 or higher, the liquid composition can be made to have a viscosity suitable for inkjet ejection, and an insulating layer with sufficient strength can be obtained. Furthermore, the resulting insulating layer is preferable because it does not dissolve in the electrolyte even in an oxidized state. When the weight-average molecular weight (Mw) of the binder for forming the insulating layer is 80,000 or less, the thixotropy of the liquid composition decreases, making it possible to stably eject it by inkjet and obtain a uniform insulating layer.

[0033] There are no particular restrictions on the method for measuring the weight-average molecular weight (Mw) of the binder used to form the insulating layer; it can be appropriately selected depending on the purpose. For example, it can be measured by gel permeation chromatography (GPC). More specifically, the weight-average molecular weight of the binder used to form the insulating layer can be measured by scraping off the insulating layer, immersing it in a solvent such as tetrahydrofuran (THF) to dissolve the resin components, and then performing analysis.

[0034] There are no particular restrictions on the content of the binder for forming the insulating layer, and it can be appropriately selected according to the purpose, but it is preferable that it be 1% by mass or more and 5% by mass or less relative to the total amount of insulating inorganic particles in the insulating layer. If the content of the binder for forming the insulating layer is 1% by mass or more relative to the total amount of insulating inorganic particles in the insulating layer, an insulating layer with sufficient strength can be obtained. When the content of the binder for forming the insulating layer is 5% by mass or less relative to the total amount of insulating inorganic particles in the insulating layer, thixotropy can be reduced, improving inkjet ejection performance and suppressing nozzle clogging and ejection abnormalities (ejection curves and abnormal ejection speed). The resulting insulating layer is preferable because it does not suffer from problems such as reduced output due to increased battery resistance and reduced cycle characteristics. More specifically, if the content of the binder for forming the insulating layer is greater than 5% by mass, the viscosity becomes excessively high, reducing IJ ejection performance. There is also a concern that some of the binder for forming the insulating layer may dissolve into the electrolyte, increasing battery resistance and reducing battery output, and potentially accelerating the deterioration of battery performance in cycle evaluation.

[0035] As a binder for forming the insulating layer, a suitable synthetic material may be used, or a commercially available product may be used. Examples of commercially available binders for forming insulating layers include Lumiflon® LF200F (manufactured by AGC Inc.), Zeffle® GK570 (manufactured by Daikin Corporation), and Zaflon® GF-X-101 and GF-400 (manufactured by Toagosei Co., Ltd.).

[0036] <Surfactants> The surfactant of the present invention is added in such a way that the dynamic surface tension of the insulating film ink at 25°C is less than 40 mN / m, and the static surface tension at 25°C is between 20 mN / m and 32 mN / m. In this case, a silicone-based surfactant is most suitable in terms of electrical stability and efficiency of the addition effect. While any silicone-based surfactant can be freely selected as long as it allows for adjustment of surface tension by addition, it is preferable that the HLB value is 12 or less, and more preferably less than 10. If the HLB value exceeds 12, the efficiency of reducing surface tension by addition is low, requiring the addition of a large amount of surfactant to obtain the target surface tension, which in turn leads to a decrease in the peel strength of the insulating film.

[0037] Ionic surfactants possess an electric charge and can cause problems with electrical stability, such as decomposition reactions within batteries or becoming the starting point for electrode corrosion reactions. Therefore, nonionic surfactants are preferable. Furthermore, aliphatic ether-type and ester-type surfactants have a low effect on surface tension when added, requiring large amounts to reach the target surface tension, which reduces the peel strength of the insulating film. For this reason, silicon-based surfactants, which have a high additive effect, are more preferable.

[0038] The amount of surfactant added is preferably 0.01% by mass or more and 0.5% by mass or less, more preferably 0.05% by mass or more and 0.4% by mass or less, and even more preferably 0.1% by mass or more and 0.3% by mass or less, relative to the total amount of insulating film ink. When the amount added is 0.01% by mass or more, it is possible to suppress problems such as dripping during inkjet ejection. When the amount added is 0.5% by mass or less, it is possible to suppress the decrease in the adhesion of the insulating film due to the effect of the surfactant.

[0039] As for the surfactant, you may use one that has been synthesized as appropriate, or you may use a commercially available product. Examples of commercially available surfactants include BYK-329, BYK-3760, BYK-379 (manufactured by BYK Corporation), KF-945, KF-352A, KF-353, and KF-6017 (manufactured by Shin-Etsu Chemical Co., Ltd.), among others.

[0040] <Solvent> The present invention uses NMP as the main solvent in its liquid composition for forming an insulating layer. It is preferable to use NMP alone. If other solvents are included, the solvents will mix when drying on the same line as the coating of the positive electrode mixture, making recovery difficult, and therefore the composition is unsuitable for use.

[0041] There are no particular restrictions on the solvent content, and it can be appropriately selected depending on the purpose. For example, it can be 40% to 70% by mass relative to the total amount of insulating film ink.

[0042] <Other ingredients> The liquid composition for forming an insulating layer of the present invention may contain other additives such as pH adjusters, rust inhibitors, preservatives, fungicides, antioxidants, reduction inhibitors, evaporation accelerators, chelating agents, and defoaming agents, but from the viewpoint of solvent recovery, it is desirable that it does not contain volatile components with a boiling point lower than NMP. There are no particular restrictions on the content of other components, and they can be set as appropriate depending on the content of various components in the liquid composition.

[0043] [viscosity] The viscosity of the insulating layer forming liquid composition of the present invention is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of improving ejection performance by inkjet, it is preferably 5.0 mPa·s or more and 30 mPa·s or less.

[0044] In the liquid composition for forming an insulating layer of the present invention, when viscosity A is measured using an E-type viscometer at 100 rpm and 25°C, and viscosity B is measured using an E-type viscometer at 10 rpm and 25°C, it is preferable that the ratio of viscosity B to viscosity A [B / A] is 0.95 or more and 1.05 or less. A ratio of viscosity B to viscosity A [B / A] of 0.95 or more and 1.05 or less indicates that the liquid composition has low thixotropy. When the ratio of viscosity B to viscosity A [B / A] is 0.95 or more and 1.05 or less, ejection defects do not occur even with continuous ejection by inkjet, and stable ejection is possible. Furthermore, problems such as nozzle clogging and ejection defects that occur during continuous ejection due to ejection deviation or abnormal ejection speed can be eliminated.

[0045] There are no particular limitations on the method for measuring the viscosity of the insulating layer-forming liquid composition of the present invention, and a suitable method can be selected depending on the purpose. For example, it can be measured using an E-type viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.) with a standard rotor of 1°34'×R24.

[0046] [surface tension] The surface tension of the insulating layer-forming liquid composition of the present invention is preferably less than 40 mN / m as a dynamic surface tension at 25°C and 20 mN / m to 32 mN / m as a static surface tension at 25°C, from the viewpoint of improving ejection performance by inkjet. If the dynamic surface tension is 40 mN / m or higher, when the insulating film is coated on the slurry or on an adjacent electrode foil immediately after coating the positive electrode slurry, wetting and spreading may occur on the slurry, potentially reducing the capacity of the positive electrode. (Hereinafter, the process of coating the insulating film immediately after coating the positive electrode slurry in this manner will be referred to as Wet-By-Wet and abbreviated as WbW.) If the static surface tension is less than 20 mN / m, it may cause problems such as dripping during continuous inkjet ejection, and if the static surface tension is greater than 32 mN / m, clogging is likely to occur during continuous inkjet ejection, making it unsuitable for use.

[0047] <Method for producing a liquid composition for forming an insulating layer> There are no particular limitations on the method for producing the insulating layer-forming liquid composition of the present invention, and can be appropriately selected depending on the purpose. For example, it can be obtained by adding and dispersing insulating inorganic particles and a dispersant in NMP to a dispersion in which an insulating layer-forming binder and other components are dissolved in NMP. The dispersion may be prepared by pre-mixing the solvent, insulating inorganic particles, and dispersant, followed by use in a disperser. There are no particular restrictions on the disperser, and it can be appropriately selected according to the purpose. Examples include homomixers, homogenizers, ultrasonic dispersers, ball mills, bead mills, cavitation mills, ejector type, venturi type, obstacle impact type, fluidized bed type dispersers, and agitated bed dispersers.

[0048] (Method of manufacturing electrodes) The liquid composition for forming an insulating layer of the present invention can be used in the method for manufacturing electrodes of the present invention. The method for manufacturing an electrode according to the present invention includes a step of applying a liquid composition for forming an electrode composite layer, a step of applying a liquid composition for forming an insulating layer, and a heating step.

[0049] <Electrode> First, the electrodes related to the present invention will be described with reference to the drawings.

[0050] Figure 1 is a schematic cross-sectional view showing an electrode related to the present invention. The electrode 100 comprises a base body 1, an electrode composite layer 2 provided on a part of the base body 1, and an insulating layer 3. The insulating layer 3 is provided at the boundary between the base body exposed portion 11 where the base body 1 is exposed and the electrode composite layer 2. Although Figure 1 illustrates a configuration in which the electrode composite layer 2 and the insulating layer 3 are provided on one side of the base body 1, the electrode composite layer 2 and the insulating resin layer 3 may be provided on both opposing sides of the base body 1.

[0051] <<Base>> As for the substrate, there are no particular restrictions as long as it has electronic conductivity and is stable to the applied potential, and it can be appropriately selected according to the purpose. Examples include aluminum foil, copper foil, stainless steel foil, titanium foil, etched foil obtained by etching these materials to create fine holes, carbon-coated foil obtained by coating the surface with a carbon-containing resin layer, and perforated substrates used in lithium-ion capacitors.

[0052] <<Electrode composite layer>> The electrode composite layer is provided on a portion of the substrate. In other words, the electrode composite layer is formed such that there are exposed portions of the substrate where the electrode composite layer is not provided, for the purpose of providing an insulating layer or welding leads. The electrode composite layer (sometimes referred to as the "active material layer") is mainly composed of an active material (negative electrode active material or positive electrode active material). In this specification, "mainly composed of an active material" means that the active material content is 70% by mass or more of the total electrode composite layer.

[0053] There are no particular restrictions on the electrode composite layer, and it can be appropriately selected according to the purpose. For example, it may contain an active material (negative electrode active material or positive electrode active material), and may optionally contain a conductive additive, a binder for the electrode composite layer, a dispersant for the electrode composite layer, a solid electrolyte, and other components.

[0054] Here, Figures 2A and 2B are schematic cross-sectional views showing other examples of electrode configurations related to the present invention. The electrode composite layer may have an opening 21 as shown in Figure 2A. The number of openings 21 is preferably one or more, and more preferably multiple. The opening 21 may penetrate the electrode composite layer from the surface of the electrode composite layer to the surface of the substrate, or it may not penetrate to the surface of the substrate. The opening 21 may be a cavity or may be filled with material 22. If the opening 21 is filled with material 22, the material 22 may be a single material or a mixture of two or more materials, but in either case, the material is different from the material constituting the electrode composite layer. From the viewpoint of improving ionic conductivity, the material 22 is preferably a material having a solid electrolyte. Since the electrode composite layer having the opening 21 is easy to control during application, it can be suitably manufactured by using an inkjet as the means for forming the electrode composite layer.

[0055] As shown in Figure 2B, the electrode composite layer may have an adhesive layer 23 containing a metal that alloys with lithium between the substrate 1 and the electrode composite layer 2. Furthermore, if an adhesive layer 23 is provided between the substrate 1 and the electrode composite layer 2, the boundary between the adhesive layer 23 and the exposed substrate portion 11 is defined as the boundary portion in this invention.

[0056] <<<Active material>>> As the active material, a positive electrode active material or a negative electrode active material can be used. The positive electrode active material or the negative electrode active material may be used alone, or two or more may be used in combination.

[0057] -Cathode active material- As the positive electrode active material, there are no particular restrictions as long as it is a material that can reversibly intercept and release alkali metal ions, but alkali metal-containing transition metal compounds can be used. 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 cobaltate, lithium nickelate, and lithium manganeseate.

[0058] As alkali metal-containing transition metal compounds, polyanionic compounds having an XO4 tetrahedron (X=P, S, As, Mo, W, Si, etc.) in their crystal structure can be used. Among these, lithium-containing transition metal phosphate compounds such as lithium iron phosphate and lithium vanadium phosphate are preferred from the viewpoint of cycle characteristics, and lithium vanadium phosphate is more preferred from the viewpoint of lithium diffusion coefficient and power characteristics. Furthermore, when using polyanionic compounds, it is preferable that the surface is coated with a conductive additive such as a carbon material to form a composite, in terms of electronic conductivity.

[0059] It is preferable that the alkali metal-containing transition metal compound has at least a portion of its surface coated with an ion-conducting oxide. Lithium ion-conducting oxide is preferred as the ion-conducting oxide. There are no particular restrictions on lithium-ion conductive oxides, and they can be appropriately selected according to the purpose. For example, Li x AO y Examples of oxides represented by (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) include: Specific examples of lithium-ion conductive oxides include Li3BO3, LiBO2, Li2CO3, LiAlO2, Li4SiO4, Li2SiO3, Li3PO4, Li2SO4, Li2TiO3, and Li4Ti5O 12 Examples include Li2Ti2O5, Li2ZrO3, LiNbO3, LiTaO3, Li2MoO4, and Li2WO4. Among these, Li4Ti5O 12 Li2ZrO3 or LiNbO3 are preferred. Furthermore, the lithium-ion conductive oxide may be a composite oxide. Any combination of lithium-ion conductive oxides can be used as the composite oxide, for example, Li4SiO4-Li3BO3 and Li4SiO4-Li3PO4.

[0060] -Negative electrode active material- The negative electrode active material is not particularly limited as long as it is a material that can reversibly intercept and release alkali metal ions, and can be appropriately selected according to 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, hard carbon (difficult to graphitize), and soft carbon (easily graphitizable). Other materials besides carbon include, for example, lithium titanate and titanium oxide. From the viewpoint of increasing the energy density of lithium-ion batteries, high-capacity materials such as silicon, tin, silicon alloys, tin alloys, silicon oxide, silicon nitride, and tin oxide can also be suitably used as negative electrode active materials.

[0061] <<<Conductive additive>>> There are no particular restrictions on the conductive additive, and it can be appropriately selected depending on the purpose. For example, carbon black produced by the furnace method, acetylene method, gasification method, etc., or carbon materials such as carbon nanofibers, carbon nanotubes, graphene, and graphite particles can be used. Other conductive additives besides carbon materials include, for example, metal particles such as aluminum, metal fibers, etc. The conductive additive may also be pre-compounded with the active material.

[0062] There are no particular restrictions on the content of the conductive additive relative to the active material, and it can be set appropriately depending on the purpose, but it is preferably 10% by mass or less, and more preferably 8% by mass or less. A concentration of 10% by mass or less of the conductive additive relative to the active material is preferable because it improves the stability of the liquid composition for forming the electrode composite layer. A concentration of 8% by mass or less of the conductive additive relative to the active material is preferable because it further improves the stability of the liquid composition for forming the electrode composite layer.

[0063] <<<Binder for electrode composite layer>>> The binder for the electrode composite layer is not particularly limited as long as it can bind the negative electrode materials together, the positive electrode materials together, the negative electrode material to the negative electrode substrate, and the positive electrode material to the positive electrode substrate, and can be appropriately selected according to the purpose. When the liquid composition for forming the electrode composite layer is used for inkjet ejection, it is preferable that the binder for the electrode composite layer does not easily increase the viscosity of the liquid composition for forming the electrode composite layer, from the viewpoint of suppressing nozzle clogging of the liquid ejection head. In this specification, the term "binder" or "binder for insulating layer" in a liquid composition for forming an insulating layer is distinguished from the term "binder for electrode composite layer" in a liquid composition for forming an electrode composite layer.

[0064] A polymer compound can be used as the binder for the electrode composite layer. Examples of polymer compounds include polyvinylidene fluoride (PVDF), acrylic resins, polyethylene, polypropylene, polyurethane, nylon, polytetrafluoroethylene, polyphenylene sulfide, polyethylene tephthalate, polybutylene tephthalate and other thermoplastic resins, polyamide compounds, polyimide compounds, polyamide-imides, ethylene-propylene-butadiene rubber (EPBR), styrene-butadiene rubber (SBR), nitrile butadiene rubber (NBR), isoprene rubber, polyisobutene, polyethylene glycol (PEO), polymethylmecryl acid (PMMA), and polyethylene vinyl acetate (PEVA).

[0065] There are no particular restrictions on the content of the electrode composite layer binder relative to the active material, and it can be set appropriately according to the purpose, but it is preferably 1% by mass or more and 15% by mass or less, and more preferably 3% by mass or more and 10% by mass or less. When the content of the electrode composite layer binder relative to the active material is 1% by mass or more, the active material can be firmly bound to the substrate, which is preferable.

[0066] <<<Dispersant for electrode composite layer>>> As the dispersant for the electrode composite material layer, there is no particular limitation as long as it can improve the dispersibility of the active material in the liquid composition for forming the electrode composite material layer. For example, polymer dispersants such as polyethylene oxide-based, polypropylene oxide-based, polycarboxylic acid-based, naphthalene sulfonic acid formalin condensation-based, polyethylene glycol-based, polycarboxylic acid partial alkyl ester-based, polyether-based, polyalkylene polyamine-based; low molecular weight dispersants such as alkyl sulfonic acid-based, quaternary ammonium-based higher alcohol alkylene oxide-based, polyhydric alcohol ester-based, alkyl polyamine-based; inorganic dispersants such as polyphosphate-based dispersants, etc. can be mentioned. In addition, in this specification, the "dispersant having a carboxyl group or acid anhydride group" in the liquid composition for forming the insulating layer is distinguished from the "dispersant for the electrode composite material layer" in the liquid composition for forming the electrode composite material layer.

[0067] <<<Solid electrolyte>>> As the solid electrolyte, there is no particular limitation as long as it is a solid substance having electron insulation and exhibiting ionic conductivity. From the viewpoint of having high ionic conductivity, sulfide solid electrolytes and oxide-based solid electrolytes are preferred.

[0068] Examples of the sulfide solid electrolyte include Li 10 GeP2S 12 , and Li6PS5X (X = F, Cl, Br, I) having an argyrodite-type crystal structure, etc. can be mentioned. Examples of the oxide-based solid electrolyte include LLZ (Li7La3Zr2O 12 ) having a garnet-type crystal structure, LATP (Li 1+x Al x Ti 2-x (PO4)3) (0.1 ≦ x ≦ 0.4) having a NASICON-type crystal structure, LLT (Li 0.33 La 0.55 TiO3) having a perovskite-type crystal structure, amorphous LIPON (Li 2.9 PO 3.3 N 0.4 ), etc. can be mentioned. These solid electrolytes may be used alone or in combination of two or more.

[0069] When the electrode composite layer is a positive electrode composite layer, there are no particular restrictions on the average thickness of the positive electrode composite layer, and it can be appropriately selected according to the purpose, but it is preferably 10 μm or more and 300 μm or less, and more preferably 40 μm or more and 150 μm or less. When the average thickness of the positive electrode composite layer is 10 μm or more, the energy density of the electrochemical element improves. When the average thickness of the negative electrode composite layer is 300 μm or less, the load characteristics of the electrochemical element are improved.

[0070] When the electrode composite layer is the negative electrode composite layer, there are no particular restrictions on the average thickness of the negative electrode composite layer, and it can be appropriately selected according to the purpose, but it is preferably 10 μm or more and 450 μm or less, and more preferably 20 μm or more and 100 μm or less. When the average thickness of the negative electrode composite layer is 10 μm or more, the energy density of the electrochemical element improves. When the average thickness of the negative electrode composite layer is 450 μm or less, the cycle characteristics of the electrochemical element are improved.

[0071] The electrode composite layer may be formed on both sides of the substrate (positive electrode substrate and / or negative electrode substrate). Furthermore, multiple electrodes may be stacked to increase the charge / discharge capacity of the electrodes. There are no particular restrictions on the number of stacked positive and negative electrodes, and they can be increased as needed.

[0072] <<Insulating layer>> The insulating layer in the electrode according to the present invention is provided so as to cover the boundary between the substrate exposed portion 11 where the substrate is exposed and the electrode composite layer 2.

[0073] Here, Figures 3A and 3B are schematic cross-sectional views showing other examples of electrode configurations related to the present invention. As shown in Figure 3A, the insulating layer 3 may be provided at the boundary and at the end of the electrode composite layer 2. As shown in Figure 3B, the insulating layer 3 may be provided at the boundary and on the upper surface of the electrode composite layer 2. When the insulating layer 3 is provided on the upper surface of the electrode composite layer 2, the coverage rate of the upper surface of the electrode composite layer 2 by the insulating layer 3 is preferably 90% or more, more preferably 95% or more, and even more preferably 100%. In other words, when the insulating layer 3 is provided on the upper surface of the electrode composite layer 2, there may be exposed areas on the upper surface of the electrode composite layer 2 that are not covered by the insulating layer 3. By providing the insulating layer 3 on the electrode composite layer 2, when coating by inkjet, the insulating layer can be produced with low film thickness and uniformity, thereby improving the stability of the battery.

[0074] There are no particular restrictions on the average thickness of the insulating layer, and it can be appropriately selected according to the purpose, but it is preferably 2 μm to 20 μm, and more preferably 5 μm to 10 μm. A minimum average thickness of 2 μm for the insulating layer is preferable because it provides sufficient insulation. When the average thickness of the insulating layer is 20 μm or less, problems such as the electrode composite layer being damaged by the weight of the liquid composition itself, the liquid composition flowing and causing unevenness, or seeping into the substrate can be eliminated when applying the liquid composition.

[0075] There are no particular restrictions on the method for measuring the average thickness of the insulating layer; it can be appropriately selected depending on the purpose. For example, it can be measured using a digital micrometer (manufactured by Mitutoyo Corporation).

[0076] There are no particular restrictions on the peel strength of the insulating layer from the substrate, and it can be appropriately selected according to the purpose, but it is preferably 50 N / m or more, and more preferably 100 N / m or more. If the peel strength of the insulating layer to the substrate is 50 N / m or higher, it is possible to prevent some of the insulating inorganic particles contained in the insulating layer from falling off due to friction during electrode formation using the roll-to-roll method or during transportation. This also prevents any impact on battery characteristics.

[0077] There are no particular restrictions on the method for measuring the peel strength of the insulating layer against the substrate; it can be appropriately selected depending on the purpose. One example is shown below. [Method for measuring peel strength] The evaluation device used is, for example, a light-load type adhesive / film peel analysis device (VPA-3S, manufactured by Kyowa Interface Science Co., Ltd.), and an 18mm wide tape (cellophane tape, manufactured by Nitto Co., Ltd.) is used. The tape is attached to an insulating layer, and when the peeling operation is performed at a peeling angle of 90 degrees and a speed of 30 mm / min, the load applied to the load cell is defined as the peeling strength.

[0078] There are no particular restrictions on the width of the insulating layer, and it can be appropriately selected depending on the battery configuration, but it is preferable that it be between 2 mm and 30 mm. The "width" of the insulating layer refers to the distance from one end to the other (in the longitudinal direction of the electrode) of the upper surface of the insulating layer facing the substrate surface in contact with the electrode composite layer, in a cross-sectional view obtained by cutting the electrode in the thickness direction and parallel to the length direction of the electrode. If the width of the insulating layer is 2 mm or more, it becomes difficult to follow the meandering of the electrode composite layer, and problems such as being unable to cover the exposed substrate with the insulating layer can be resolved. If the width of the insulating layer is 30 mm or less, problems such as interference with lead welding and excessive battery size relative to battery capacity can be resolved.

[0079] There are no particular restrictions on the width of the insulating layer covering the electrode composite layer, and it can be appropriately selected according to the purpose, but it is preferably 0.1 mm or more and 5 mm or less. In this specification, "cover width" refers to the distance from one end to the other (in the longitudinal direction of the electrode) on the surface that is in contact with the electrode composite layer and the insulating layer, in a cross-sectional view obtained by cutting the electrode in the thickness direction and parallel to the length direction of the electrode. If the coverage width is 0.1 mm or more, it becomes difficult to follow the meandering of the electrode composite layer, and problems such as being unable to cover the exposed substrate with an insulating layer can be resolved. If the overlap width is 5 mm or less, it is possible to prevent the insulating layer from negatively affecting the battery capacity.

[0080] <Process for applying liquid composition for electrode composite layer formation> The step of applying the liquid composition for electrode composite layer formation is a step of applying the liquid composition for electrode composite layer formation to a part of the substrate.

[0081] When manufacturing a positive electrode, a liquid composition for forming an electrode composite layer (liquid composition for forming a positive electrode composite layer) is applied to a portion of the positive electrode substrate. When manufacturing a negative electrode, a liquid composition for forming an electrode composite layer (liquid composition for forming a negative electrode composite layer) is applied to a portion of the negative electrode substrate.

[0082] There are no particular limitations on the method for applying the liquid composition for forming the electrode composite layer, and it can be appropriately selected depending on the purpose. Examples include the comma coater method, die coater method, curtain coat method, spray coat method, inkjet method, and dispenser method.

[0083] <Process of applying liquid composition for forming an insulating layer> The step of applying the liquid composition for forming an insulating layer is a step of applying the liquid composition for forming an insulating layer to the boundary between the exposed substrate portion and the electrode composite layer.

[0084] As a method for applying the liquid composition for forming the insulating layer, a liquid dispensing method such as an inkjet method or a dispenser method, which can be applied non-contact and on demand, is preferred.

[0085] <Heating process> The heating step involves heating the applied liquid composition for forming the electrode composite layer and the liquid composition for forming the insulating layer.

[0086] There are no particular restrictions on the heating method, and it can be appropriately selected according to the purpose. Examples include heating the coated surface with a resistance heater, infrared heater, or fan heater, or drying the coated surface from the back using a hot plate, drum heater, etc. From the viewpoint of uniformly heating and drying the coated surface, resistance heaters, infrared heaters, and fan heaters that can dry the coated surface without contact are preferred. These heating mechanisms may be used individually or in combination of two or more.

[0087] There are no particular restrictions on the heating temperature in the heating process, and it can be appropriately selected according to the purpose. However, from the viewpoint of protecting the active material of the substrate and electrode composite layer, it is preferable that the temperature be between 70°C and 150°C. A heating temperature of 70°C or higher during the heating process is preferable because it improves the strength of the insulating layer. It is preferable that the heating temperature in the heating process is 150°C or lower, as this prevents bubbles from bumping on the surface of the insulating layer.

[0088] <Other processes> Other processes are not particularly limited and can be selected as appropriate depending on the purpose. Examples include a process of forming an adhesive layer between the substrate and the electrode composite layer, an opening formation process of forming an opening of a desired size in the electrode composite layer, a solid electrolyte filling process of filling the opening with a solid electrolyte, a process of forming an adhesive layer between the electrode composite layer and the insulating layer, and a cutting process of cutting the electrodes to a desired size by punching or the like. [Examples]

[0089] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited in any way to these examples. In the following examples and comparative examples, unless otherwise specified, "parts" refers to "parts by mass" and "%" refers to "percentage by mass".

[0090] <Preparation of liquid composition for forming an insulating layer> A liquid composition for forming an insulating layer was obtained by weighing out 41.0% by mass of AKP-3000 as insulating inorganic particles, 0.41% by mass of AKM0531 as a dispersant, 0.82% by mass of LF-200F as a resin, 0.01% by mass of KF-352A as a surfactant, and 57.76% by mass of NMP as a dispersion medium. A pre-dispersion made by mixing these components was placed in an alumina ball mill pot along with 3 mmΦ alumina beads, and the sealed pot was placed on a mill turntable to disperse the mixture. The pot rotation speed during dispersion was 35 rpm, and dispersion was determined to be complete when the viscosity change reached a steady state.

[0091] <Measurement of dynamic surface tension> The dynamic surface tension of the liquid composition for forming an insulating layer was measured at 25°C using a dynamic surface tensimeter (SITA Messtechnik GmbH portable surface tensimeter, bubble lifetime: 70 ms).

[0092] <Measurement of static surface tension> The static surface tension of the liquid composition for forming an insulating layer was measured at 25°C using a static surface tensile meter (automatic surface tensile meter DY-300, manufactured by Kyowa Interfacial Chemical Co., Ltd.).

[0093] <Measurement of viscosity A and viscosity B> The viscosity of the liquid composition for forming the insulating layer was measured using an E-type viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.) with a standard rotor of 1°34'×R24 at a rotation speed of 100 rpm and 25°C, and this viscosity was defined as viscosity A. The viscosity was also measured in the same manner except that the rotation speed was changed to 10 rpm, and this viscosity was defined as viscosity B. Note that the sample size was 2, and the average was adopted.

[0094] <Evaluation of continuous dispensing performance> The liquid composition for forming an insulating layer was subjected to continuous ejection for 30 minutes using an inkjet head (Ricoh MH2420), and the ejection state was compared after 1 minute and 30 minutes. The evaluation criteria were as follows, with ○ to △ being considered acceptable. [Evaluation Criteria] ○: After 30 minutes of continuous dispensing, dispensing is possible from all nozzles. △: Discharge abnormalities such as misaligned discharge or poor discharge speed occur in some nozzles, but all nozzles are capable of discharging. ×: After 30 minutes of continuous dispensing, some nozzles are failing to dispense.

[0095] <Measurement and evaluation of peel strength of insulating films> Regarding the liquid composition for forming an insulating film, it was tested on aluminum foil (manufactured by UACJ Corporation, model number 1N30) using an inkjet head (manufactured by Ricoh Corporation, MH5420F) with a basis weight of 5 mg / cm².2 An insulating film was formed to achieve the desired result, and its peel strength was evaluated. The evaluation device used was a light-load type adhesive / film peel analysis device (VPA-3S, manufactured by Kyowa Interface Science Co., Ltd.), and an 18mm wide tape (cellophane tape, manufactured by Nitto Co., Ltd.) was used. The tape was attached to the insulating layer, and when the peeling operation was performed at a peeling angle of 90 degrees and a speed of 30 mm / min, the average value of the load applied to the load cell was read, and the strength was evaluated. The evaluation criteria were as follows, with ○ to △ being considered passing grades. [Evaluation Criteria] ○: Peel strength of 100 N / m or more. △: Peel strength is 50 N / m or more and less than 100 N / m. ×: Peel strength is less than 50 N / m.

[0096] <Evaluation of WbW coating properties of liquid compositions for forming insulating layers> A slurry for cathode molding was prepared by dispersing these materials in N-methylpyrrolidone (NMP) (Mitsubishi Chemical Corporation). The materials consisted of 93% by mass of lithium nickel-cobalt manganate (NCM622, manufactured by Beijing Dangben Co., Ltd.) as the positive electrode active material, 3 parts by mass of a conductive additive (Ketjenbrak, manufactured by Lion Specialty Chemicals, model no. 600JD), and 4 parts by mass of PVDF (polyvinylidene fluoride, manufactured by Solvay, model no. Solev5130) as a binder for the electrode composite layer. On an aluminum (UACJ Corporation, model number 1N30) cathode substrate, the coating amount per unit area after drying (area density) is 8.0 mg / cm². 2 After applying the positive electrode slurry so that a positive electrode composite layer was formed on one side, an insulating layer-forming liquid composition was applied to both the coated and uncoated areas, focusing on the interface between the coated and uncoated areas. Subsequently, the electrode foil was left on a hot plate at 120°C to dry, and the molding state of the electrode and insulating film was checked to evaluate the WbW coating properties. The evaluation criteria were as follows, with ○ to △ indicating a pass. Note that the WbW coating properties evaluation was performed only on samples that had no problems with the continuous discharge performance mentioned above; samples that were not evaluated are indicated with "-". [Evaluation Criteria] ○: There are no external abnormalities such as bias or voids in either the positive electrode or the insulating film. △: There is some visual unevenness in the insulating film coating, but there is no exposure of the electrode or aluminum metal parts. ×: There are significant appearance abnormalities, such as the positive electrode slurry being mixed with the liquid composition for forming the insulating layer, or aluminum being exposed in the insulating film coating area on the uncoated portion of the positive electrode.

[0097] (Examples 2-32 and Comparative Examples 1-11) In the preparation of the insulating layer-forming liquid composition of Example 1, the insulating layer-forming liquid composition was prepared in the same manner as shown in Tables 1 to 4, except that the composition was changed. The insulating layer-forming liquid composition and the insulating film were then evaluated.

[0098] [Table 1]

[0099] [Table 2]

[0100] [Table 3]

[0101] [Table 4]

[0102] The details of the materials used in each example and comparative example are as follows.

[0103] -Dispersant- • AKM0531 (maleic anhydride, manufactured by NOF Corporation) It includes structural units represented by general formula (1) and structural units represented by general formula (2). • SC0505K (maleic anhydride, manufactured by NOF Corporation) It includes structural units represented by general formula (1) and structural units represented by general formula (2). • Isoban 10 (maleic anhydride, manufactured by Kuraray Co., Ltd.) It includes structural units represented by general formula (1) and structural units represented by general formula (2). • HKM-50A (ammonium polycarboxylate salt, manufactured by NOF Corporation) It does not include either the structural unit represented by general formula (1) or the structural unit represented by general formula (2). • DISPERBY K-108 (carboxylic acid, manufactured by BIC Chemie) It does not include either the structural unit represented by general formula (1) or the structural unit represented by general formula (2). • DISPERBYK2000 (acrylic polymer, manufactured by Bic Chemie) It does not include either the structural unit represented by general formula (1) or the structural unit represented by general formula (2).

[0104] -Insulating inorganic particles- • LS-711CB (α-alumina, particle size: 600nm, manufactured by Nippon Light Metal Co., Ltd.) • CT-3000LSSG (α-alumina, particle size: 500nm, manufactured by Almatis) • AKP-3000 (α-alumina, particle size: 700nm, manufactured by Sumitomo Chemical Co., Ltd.) • BMB-07 (Boehmite, particle size: 700nm, manufactured by Kawai Coal Industries Co., Ltd.) • F-10 (Titanium dioxide, particle size: 200nm, manufactured by Showa Denko Corporation) • TZ-3YS (Zirconia, particle size: 500nm, manufactured by Tosoh Corporation) • AA1.5 (α-alumina, particle size: 1700nm, manufactured by Sumitomo Chemical Co., Ltd.) • DAM-90 (α-alumina, particle size: 74.6 nm, manufactured by Denka Co., Ltd.)

[0105] -Binder- • LF200F (Weight-average molecular weight Mw: 42,000, Number-average molecular weight Mn: 15,000, manufactured by AGC Inc.) It has a fluoroethylene group and a vinyl ether group. • GF-X-101 (Weight-average molecular weight Mw: 27,000, Number-average molecular weight Mn: 12,000, manufactured by Toagosei Co., Ltd.) It has a fluoroethylene group and a vinyl ether group. • GF-400 (Weight-average molecular weight Mw: 77,000, Number-average molecular weight Mn: 26,000, manufactured by Toagosei Co., Ltd.) It has a fluoroethylene group and a vinyl ether group. • EPI-5310 (Weight-average molecular weight Mw: 60,000, Number-average molecular weight Mn: 30,000, Manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) It does not contain either a fluoroethylene group or a vinyl ether group. • LF916F (Weight-average molecular weight Mw: 11,000, Number-average molecular weight Mn: 5,000, manufactured by AGC Inc.) It has a fluoroethylene group and a vinyl ether group. • KF850 (Weight-average molecular weight Mw: 200,000, manufactured by Kureha Corporation) It has a fluoroethylene group but does not have a vinyl ether group.

[0106] - Surfactants - • KF-945 (Silicon-based, HLB value: 4, manufactured by Shin-Etsu Chemical Co., Ltd.) • KF-352A (Silicon-based, HLB value: 7, manufactured by Shin-Etsu Chemical Co., Ltd.) • KF-353 (Silicon-based, HLB value: 10, manufactured by Shin-Etsu Chemical Co., Ltd.) • KF-351A (Silicon-based, HLB value: 12, manufactured by Shin-Etsu Chemical Co., Ltd.) • BYK-329 (Silicon-based, HLB value: not disclosed, manufactured by BYK Corporation) • BYK-3760 (Silicon-based, HLB value: not disclosed, manufactured by BYK Corporation) • BYK-379 (Silicon-based, HLB value: not disclosed, manufactured by BYK Corporation) • Sanol LM-1140T (anionic, HLB value: not disclosed, manufactured by Lion Specialty Chemicals Co., Ltd.) • Lipocard T-28 (cationic, HLB value: not disclosed, manufactured by Lion Specialty Chemicals Co., Ltd.) • Nonionic HT-505 (nonionic, HLB value: not disclosed, manufactured by NOF Corporation) • Futtergent 250 (fluorine-based, HLB value: not disclosed, manufactured by Neos Co., Ltd.)

[0107] As shown in Examples 1 to 32, the liquid composition for forming an insulating layer of the present invention was found to be able to form an insulating film with excellent continuous discharge properties and WbW coating properties, as well as excellent peel strength, while using NMP as the main solvent.

[0108] Although embodiments of the present invention have been described above, the present invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope of the invention as described in the claims.

[0109] The embodiments of the present invention are, for example, as follows. <1> It contains insulating inorganic particles, a dispersant having a carboxyl group or an acid anhydride group, a binder, and a surfactant. A liquid composition for forming an insulating layer, using N-methyl-2-pyrrolidone as the main solvent, The weight-average molecular weight of the binder is 25,000 or more and 80,000 or less. The dynamic surface tension at 25°C is less than 40 mN / m. This is a liquid composition for forming an insulating layer, characterized by having a static surface tension of 20 mN / m or more and 32 mN / m or less at 25°C. <2> The viscosity A measured using an E-type viscometer under conditions of 100 rpm and 25°C is characterized by being between 5 mPa·sec and 20 mPa·sec. <1> This is a liquid composition for forming an insulating layer as described above. <3> When viscosity A is measured using an E-type viscometer under conditions of 100 rpm and 25°C, and viscosity B is measured using an E-type viscometer under conditions of 10 rpm and 25°C, the ratio of viscosity B to viscosity A [B / A] is 0.95 or more and 1.05 or less. <1> from <2> The liquid composition for forming an insulating layer as described in any one of the items. <4> The surfactant is characterized by being a polyether-modified polysiloxane. <1> from <3> The liquid composition for forming an insulating layer as described in any one of the items. <5> The surfactant is characterized by having an HLB value of 12 or less. <1> from <4> The liquid composition for forming an insulating layer as described in any one of the items. <6> The amount of the surfactant added is characterized to be 0.01% by mass or more and 0.5% by mass or less. <1> from <5> The liquid composition for forming an insulating layer as described in any one of the items. <7> The binder is characterized by having a fluoroethylene group and a vinyl ether group. <1> from <6> The liquid composition for forming an insulating layer as described in any one of the items. <8> The dispersant is characterized by containing at least one selected from the structural units represented by the following general formula (1), the structural units represented by the following general formula (2), and the structural units represented by the following general formula (3). <1> from <7> The liquid composition for forming an insulating layer as described in any one of the items. [ka] [ka] [ka] (In general formulas (1) to (3), * represents a bonding site with an adjacent main chain structural unit, and M represents an ammonium salt. n, m, and l are integers that may be different from each other.) <9> The insulating inorganic particles are characterized in that the insulating layer is α-alumina or boehmite, as described in claim 1. <10> The median diameter of the insulating inorganic particles is characterized by being 200 nm or more and less than 1,000 nm. <1> from <10> The liquid composition for forming an insulating layer as described in any one of the items. <11> Substrate and, An electrode composite layer provided on a part of the substrate, A method for manufacturing an electrode having an insulating layer covering the boundary between the exposed portion of the substrate and the electrode composite layer, A step of applying a liquid composition for forming an electrode composite layer, in which a liquid composition for forming an electrode composite layer using N-methyl-2-pyrrolidone as the main solvent is applied to a part of the substrate, An insulating layer forming liquid composition application step, wherein the insulating layer forming liquid composition according to any one of claims 1 to 10 is applied to the boundary between the substrate exposed portion where the substrate is exposed and the region to which the electrode composite layer forming liquid composition has been applied, A heating step of heating the provided electrode composite layer forming liquid composition and the insulating layer forming liquid composition, This is a method for manufacturing electrodes, characterized by including [a specific component]. <12> It contains insulating inorganic particles, a dispersant having a carboxyl group or an acid anhydride group, a binder, a surfactant, and N-methyl-2-pyrrolidone as the main solvent. The weight-average molecular weight of the binder is 25,000 or more and 80,000 or less. The dynamic surface tension at 25°C is less than 40 mN / m. This inkjet liquid composition is characterized by having a static surface tension of 20 mN / m or more and 32 mN / m or less at 25°C.

[0110] The aforementioned <1> from <10> The liquid composition for forming an insulating layer described above, <11> The method for manufacturing electrodes described above, and the preceding <12> The inkjet liquid composition described above can solve the aforementioned problems of the conventional method and achieve the objectives of the present invention. [Explanation of symbols]

[0111] 100 electrodes 1 Base 11 Exposed base part 2 Electrode composite layer 3. Insulating layer [Prior art documents] [Patent Documents]

[0112] [Patent Document 1] Patent No. 6887103 [Patent Document 2] Japanese Patent Publication No. 2023-091628 [Patent Document 3] Japanese Patent Publication No. 2023-131728

Claims

1. It contains insulating inorganic particles, a dispersant having a carboxyl group or an acid anhydride group, a binder, and a surfactant. A liquid composition for forming an insulating layer, using N-methyl-2-pyrrolidone as the main solvent, The weight-average molecular weight of the binder is 25,000 or more and 80,000 or less. The dynamic surface tension at 25°C is less than 40 mN / m. A liquid composition for forming an insulating layer, characterized in that its static surface tension at 25°C is 20 mN / m or more and 32 mN / m or less.

2. The liquid composition for forming an insulating layer according to claim 1, characterized in that the viscosity A measured using an E-type viscometer under conditions of 100 rpm and 25°C is 5 mPa·sec or more and 20 mPa·sec or less.

3. The liquid composition for forming an insulating layer according to claim 1, characterized in that when viscosity A is measured using an E-type viscometer under the conditions of 100 rpm and 25°C, and viscosity B is measured using an E-type viscometer under the conditions of 10 rpm and 25°C, the ratio of viscosity B to viscosity A [B / A] is 0.95 or more and 1.05 or less.

4. The liquid composition for forming an insulating layer according to claim 1, characterized in that the surfactant is a polyether-modified polysiloxane.

5. The liquid composition for forming an insulating layer according to claim 1, characterized in that the HLB value of the surfactant is 12 or less.

6. The liquid composition for forming an insulating layer according to claim 1, characterized in that the amount of surfactant added is 0.01% by mass or more and 0.5% by mass or less.

7. The liquid composition for forming an insulating layer according to claim 1, characterized in that the binder has a fluoroethylene group and a vinyl ether group.

8. The liquid composition for forming an insulating layer according to claim 1, characterized in that the dispersant comprises at least one selected from the following general formula (1), the following general formula (2), and the following general formula (3). 【Chemistry 1】 【Chemistry 2】 【Transformation 3】 (In general formulas (1) to (3), * represents a bonding site with an adjacent main chain structural unit, and M represents an ammonium salt. n, m, and l are integers that may be different from each other.)

9. The insulating inorganic particles are α-alumina or boehmite, characterized in that the liquid composition for forming an insulating layer according to claim 1.

10. The liquid composition for forming an insulating layer according to claim 1, characterized in that the median diameter of the insulating inorganic particles is 200 nm or more and less than 1,000 nm.

11. Substrate and, An electrode composite layer provided on a part of the substrate, A method for manufacturing an electrode having an insulating layer covering the boundary between the exposed portion of the substrate and the electrode composite layer, A step of applying a liquid composition for electrode composite layer formation, in which a liquid composition for electrode composite layer formation using N-methyl-2-pyrrolidone as the main solvent is applied to a part of the substrate, An insulating layer forming liquid composition application step, wherein the insulating layer forming liquid composition according to any one of claims 1 to 10 is applied to the boundary between the substrate exposed portion where the substrate is exposed and the region to which the electrode composite layer forming liquid composition has been applied, A heating step of heating the provided electrode composite layer forming liquid composition and the insulating layer forming liquid composition, A method for manufacturing electrodes, characterized by including the following:

12. It contains insulating inorganic particles, a dispersant having a carboxyl group or an acid anhydride group, a binder, a surfactant, and N-methyl-2-pyrrolidone as the main solvent. The weight-average molecular weight of the binder is 25,000 or more and 80,000 or less. The dynamic surface tension at 25°C is less than 40 mN / m. A liquid inkjet composition characterized by having a static surface tension of 20 mN / m or more and 32 mN / m or less at 25°C.

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