Insulating layer forming liquid composition, storage container, electrode and manufacturing apparatus thereof, and electricity storage device

Abstract

An insulating layer forming liquid composition is provided that includes insulating inorganic particles, a dispersant including a carboxyl group or an acid anhydride group, and a binder. The binder has a weight average molecular weight of 25,000 or more and 80,000 or less.

Description

FN202401504[DESCRIPTION][Title of Invention]INSULATING LAYER FORMING LIQUID COMPOSITION, STORAGE CONTAINER, ELECTRODE AND MANUFACTURING APPARATUS THEREOF, AND ELECTRICITY STORAGE DEVICE[Technical Field]

[0001] The present disclosure relates to an insulating layer forming liquid composition, a storage container, an electrode and a manufacturing apparatus thereof, and an electricity storage device.[Background Art]

[0002] Conventionally, in an electricity storage device such as a lithium ion secondary battery, an electric double layer capacitor, a lithium ion capacitor, or a redox capacitor, a paper, a nonwoven fabric, a porous film, or the like has been used as a separator to prevent a short circuit between a positive electrode and a negative electrode.If the separator melts or shrinks due to overheating, an internal short circuit may occur. In this case, the separator shrinks further due to the short-circuit reaction heat which is instantly generated. Then, the short-circuited part expands to promote abnormal heating, and this may cause thermal runaway and fire in the battery. To prevent such a short-circuit reaction, a technique has been proposed in which an insulating layer is provided in a site where the internal short circuit is likely to occur.For example, in attempting to prevent an increase in a battery temperature after an internal short circuit caused by inclusion of a foreign matter, a nonaqueous electrolyte secondary battery has been proposed that includes a protective layer that covers a boundary between an exposed portion where a current collector is exposed (where no active material layer is formed) and an active material layer, the protective layer including a curable resin and inorganic particles (see, e.g., Patent literature 1).Further, in attempting to improve the strength of the insulating layer, maintaining battery characteristics, providing good stability, and the like, an electrochemical element or an electrode has been proposed that includes an insulating layer including a compound having a hydroxyl group at the end as a binder and a compound having a carboxyl group as a dispersant (see, e.g., Patent literatures 2 and 3).[Citation List][Patent Literature]

[0003] Patent Literature 1: Japanese Patent No. 6887103Patent Literature 2: JP 2023-091628 APatent Literature 3: JP 2023-131728 AFN202401504[Summary of Invention] [Technical Problem]

[0004] An object of the present invention is to provide an insulating layer forming liquid composition that is excellent in ejection properties, continuous ejection properties, and redispersibility, and that can obtain an insulating layer having excellent strength.[Solution to Problem]

[0005] According to embodiments of the present invention, an insulating layer forming liquid composition is provided that includes insulating inorganic particles, a dispersant including a carboxyl group or an acid anhydride group, and a binder. The binder has a weight average molecular weight of 25,000 or more and 80,000 or less.[Advantageous Effects of Invention]

[0006] Embodiments of the present invention provides an insulating layer forming liquid composition that is excellent in ejection properties, continuous ejection properties, and redispersibility, and that can obtain an insulating layer having excellent strength. [Brief Description of Drawings]

[0007] A more complete appreciation of embodiments of the present disclosure and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to the accompanying drawings.[FIG. 1]FIG. 1 is a schematic cross-sectional view of an electrode according to an embodiment of the present invention.[FIG. 2A]FIG. 2A is a schematic cross-sectional view of an electrode according to an embodiment of the present invention.[FIG. 2B]FIG. 2B is a schematic cross-sectional view of an electrode according to an embodiment of the present invention.[FIG. 3A]FIG. 3A is a schematic cross-sectional view of an electrode according to an embodiment of the present invention.[FIG. 3B]FIG. 3B is a schematic cross-sectional view of an electrode according to an embodiment of the present invention.[FIG. 4]FN202401504FIG. 4 is a schematic diagram illustrating an electrode manufacturing apparatus according to an embodiment of the present invention.[FIG. 5]FIG. 5 is a schematic diagram illustrating an electrochemical element according to an embodiment of the present invention.[FIG. 6]FIG. 6 is a schematic diagram illustrating an electricity storage device according to an embodiment of the present invention.The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views.[Description of Embodiments]

[0008] In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result.Referring now to the drawings, embodiments of the present disclosure are described below. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.As in the case of the nonaqueous electrolyte secondary battery described in Patent literature 1, inkjet is preferable as a means for applying the insulating layer forming liquid composition thinly and uniformly with good positional precision to an active material layer and a substrate formed by a roll-to-roll production process. Inkjet printing can apply the insulating layer forming liquid composition to the appropriate position while detecting the boundary between the current collector exposed portion and the active material layer by ON / OFF control of each nozzle. Further, the application amount can be controlled by adjusting the droplet amount ejected from each nozzle hole.In general, the insulating layer forming liquid composition is obtained by uniformly dispersing solid components (inorganic particles, a binder, and a dispersant) in a solvent. Conventionally (including the invention described in Patent literature 1), a polymeric fluorine compound such as polyvinylidene fluoride, a curable resin, modified rubber, or the like has been used as a binder for the insulating layer forming liquid composition. However, these materials have high molecular weights, making it difficult for them to form droplets. Thus, these materials are unsuitable for ejection by inkjet. Further, even if a binder with low molecular weight is used, the thixotropy tends to be high, and there is a problem in that it is difficult to achieve stable continuous ejection using inkjet.FN202401504

[0009] The electrochemical element or electrode described in Patent literatures 2 and 3 has a concern that the film strength of the insulating layer is insufficient when the insulating layer is dried and then wound around a roll in the roll-to-roll production process, so that some of the inorganic particles may peel off due to friction or the like during winding and may be mixed into the electrolytic liquid as impurities.

[0010] An insulating layer forming liquid composition according to embodiments of the present invention can fully resolve the various concerns in the related art. More specifically an insulating layer forming liquid composition can be obtained that is excellent in ejection properties and continuous ejection properties and that can obtain an insulating layer having excellent strength. Also, an insulating layer forming liquid composition can be obtained that is excellent in redispersibility as basic performance.

[0011] The details of embodiments of the present invention are described below.

[0012] (Insulating layer forming liquid composition)An insulating layer forming liquid composition according to embodiments of the present invention includes insulating inorganic particles, a dispersant having a carboxyl group or an acid anhydride group, and a binder, and may include a solvent and other components as necessary.

[0013] In the present specification, the term “insulating layer forming liquid composition” may be simply referred to as “liquid composition”.In the present specification, the term “dispersant having a carboxyl group or an acid anhydride group” may be simply referred to as “dispersant”.In the present specification, the term “binder” may be referred to as “insulating layer forming binder”.

[0014] The insulating layer forming liquid composition according to embodiments of the present invention has low thixotropy, and thus has excellent ejection properties and continuous ejection properties in inkjet, as well as excellent redispersibility after long-term storage. Further, when the insulating layer forming liquid composition is formed into a film, an insulating layer with excellent strength can be obtained. Such an insulating layer does not peel off even when the battery is repeatedly charged and discharged.

[0015] < Insulating inorganic particles >FN202401504In the present specification, the term “insulating” means that the volume resistivity is 108Q cm or more. That is, insulating inorganic particles in the present disclosure refer to inorganic particles with a volume resistivity of 108Q cm or more.

[0016] The insulating inorganic particles are not particularly limited and can be appropriately selected depending on the purpose, so long as they have a volume resistivity of 108Q cm or more. Examples of the insulating inorganic particles include, but are not limited to, aluminum oxide (alumina), boehmite, silica, aluminum nitride, silicon nitride, cordierite, sialon, mullite, steatite, yttria, zirconia, and silicon carbide. Of these, an inorganic oxide is preferable, aluminum oxide and boehmite are more preferable, and a-alumina is even more preferable.

[0017] a- Alumina is known to function as a scavenger for a “junk” chemical species, that is, a chemical species that can cause capacity fade in lithium ion secondary batteries. Further, alumina particles have good wettability and affinity for an electrolyte, improving the cycle performance of lithium ion secondary batteries. When a-alumina is used as the insulating inorganic particles, the redispersibility and inkjet ejection properties of the liquid composition improve, and the heat resistance of the insulating layer improves.These insulating inorganic particles may be used alone or in combination of two or more types.

[0018] The shape of the insulating inorganic particles is not particularly limited and can be appropriately selected depending on the purpose. The shape may be, for example, rectangular, spherical, elliptical, cylindrical, egg-shaped, dog-bone shaped, and amorphous. Of these, from the viewpoint of improving ejection properties by inkjet, the insulating inorganic particles preferably have a shape in which the aspect ratio between the long side and the short side is close to 1.

[0019] The median diameter of the insulating inorganic particles is not particularly limited and can be appropriately selected depending on the purpose. However, the median diameter is preferably 200 nm or more and 1,000 nm or less.When the insulating inorganic particles have a median diameter of 200 nm or more, the particles are prevented from floating in the air (the occurrence of mist) during ejection by inkjet. Further, the insulating inorganic particles are prevented from adhering to the substrate due to fine particles falling off from the insulating layer.When the insulating inorganic particles have a median diameter of 1,000 nm or less, nozzle clogging during ejection by inkjet can be eliminated, improving ejection properties. Further, this is preferable because the thickness of the insulating layer is made uniform and the insulating layer is made homogenous (with less unevenness).FN202401504

[0020] A method for measuring the median diameter of the insulating inorganic particles is not particularly limited and can be appropriately selected depending on the purpose. For example, the liquid composition is diluted so that the solid content is 10% by mass or less, and then the median diameter can be measured using a concentrated-type particle size analyzer (e.g., FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.).

[0021] The insulating inorganic particles preferably include first insulating inorganic particles having a median diameter of 200 nm or more and less than 1,000 nm, and second insulating inorganic particles having an average Stokes diameter of less than 30 nm. The average Stokes diameter refers to an average value of the major axis of particles measured by observation, for example, using a transmission electron microscope (TEM).When the second insulating inorganic particles having an average Stokes diameter of less than 30 nm are included, the energy barrier in the interaction potential energy between the particles can be made sufficiently small, thereby solving a problem such as the one in which the insulating inorganic particles which are aggregated after the liquid composition is left standing for a long period of time are not redispersed even if the liquid composition is stirred again.

[0022] The content of the insulating inorganic particles is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of making the thickness of the insulating layer uniform after drying, the content is preferably 20% by mass or more and 50% by mass or less, more preferably 25% by mass or more and 48% by mass or less, even more preferably 35% by mass or more and 45% by mass or less, relative to the total amount of the liquid composition.When the content of the insulating inorganic particles is 20% by mass or more relative to the total amount of the liquid composition, exudation of the insulating inorganic particles from the resulting insulating layer onto the substrate and the electrode composite layer can be prevented.When the content of the insulating inorganic particles is 50% by mass or less relative to the total amount of the liquid composition, nozzle clogging during ejection by inkjet can be eliminated, and ejection properties can be improved. Further, this makes the insulating layer homogenous, which is preferable.

[0023] As the insulating inorganic particles, appropriately synthesized particles or commercially available products may be used.Examples of the commercially available aluminum oxide products as the insulating inorganic particles include, but are not limited to, by product 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, andFN202401504AKP-G15 (all high purity alumina manufactured by Sumitomo Chemical Co., Ltd.), TM-DA, TM-DAR, and TM-5D (all manufactured by Taimei Chemicals Co., Ltd.), CT-3000LSSG (manufactured by Almatis), LS-502, LS-711CB, and SLS-710 (all manufactured by Nippon Light Metal Co., Ltd), and SEPal-60 and SEPal-70 (all manufactured by Arteo).

[0024] <Dispersant having carboxyl group or acid anhydride group>The dispersant in the present disclosure has a carboxyl group or an acid anhydride group. The carboxyl group has a repulsive effect between dispersant molecules due to steric hindrance. Thus, when the dispersant having the carboxyl group is added to the liquid composition, the insulating inorganic particles in the liquid composition can be uniformly dispersed as primary particles, and the dispersed state can be maintained for a long period of time without having re-aggregation. The acid anhydride group has excellent compatibility with the insulating layer forming binder, thus reducing thixotropy in the liquid composition. Further, the carboxyl group or the acid anhydride group can improve ejection properties by inkjet due to each of their effects. Further, in the resulting insulating layer, a decrease in output due to an increase in battery resistance and a decrease in cycle characteristics, caused by the dispersant dissolving into the electrolytic liquid, can be prevented.

[0025] The dispersant having the acid anhydride group is not particularly limited and can be appropriately selected depending on the purpose. Examples of thereof include, but are not limited to, a dispersant including a structural unit represented by a general formula (1).... General Formula (1)In the general formula (1), * represents a bonding site to an adjacent main chain structural unit, and M represents an ammonium salt.

[0027] The dispersant having the carboxyl group is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, a dispersant including a structural unit represented by a general formula (2) and a dispersant including a structural unit represented by a general formula (3).

[0028] [Chemical 2]FN202401504... General Formula (2)

[0029] [Chemical 3]... General Formula (3)In the general formulas (2) and (3), * represents a bonding site to an adjacent main chain structural unit, and M represents an ammonium salt.

[0030] In the general formula (1), n is not particularly limited and can be appropriately selected depending on the purpose. For example, n can be 10 to 500, and is preferably 30 to 100. In the general formula (2), m is not particularly limited and can be appropriately selected depending on the purpose. For example, m can be 10 to 500, and is preferably 30 to 100. In the general formula (3), 1 is not particularly limited and can be appropriately selected depending on the purpose. For example, 1 can be 10 to 500, and is preferably 30 to 100.

[0031] A method for determining whether or not the dispersant includes the structural unit represented by any of the general formulas (1) to (3) is not particularly limited and can be appropriately selected depending on the purpose. Examples of the method include, but are not limited to, nuclear magnetic resonance (NMR) equipment and Fourier transform infrared spectroscopy (FT-IR). More specifically, whether or not each structural unit is included can be determined by scraping off the insulating layer, immersing the scraped insulating layer in a solvent such as tetrahydrofuran (THF) to dissolve resin components, and then analyzing the resin components.

[0032] FN202401504The molecular weight of the dispersant is not particularly limited and can be appropriately selected depending on the purpose. For example, the number average molecular weight of the dispersant can be 1,000 or more and 100,000 or less.When the dispersant with a number average molecular weight of 1,000 or more is used, the insulating inorganic particles are excellently dispersed.When the dispersant with a number average molecular weight of 100,000 or less is used, excellent inkjet ejection properties are achieved.A method for analyzing the molecular weight of the dispersant is not particularly limited and can be appropriately selected depending on the purpose. For example, the molecular weight can be measured by gel permeation chromatography (GPC manufactured by Shimadzu Corp.).

[0033] The content of the dispersant in the insulating layer is not particularly limited and can be appropriately selected depending on the purpose. However, the content is preferably 0.5% by mass or more and 5% by mass or less, more preferably 1% by mass or more and 3% by mass or less, relative to the total amount of the insulating inorganic particles in the insulating layer. If the content of the dispersant is 0.5% by mass or more relative to the total amount of the 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. Accordingly, the ejection properties by inkjet can be improved. Further, in the resulting insulating layer, the surfaces of the insulating inorganic particles are covered, thereby preventing the insulating inorganic particles from falling off from the insulating layer.When the content of the dispersant is 5% by mass or less relative to the total amount of the insulating inorganic particles in the insulating layer, the thixotropy can be reduced. Further, this can eliminate problems such as the dispersant dissolving into the electrolytic liquid and affecting battery performance in the resulting insulating layer.

[0034] As the dispersant, a suitably synthesized dispersant or a commercially available product may be used.Examples of the commercially available dispersant include, but are not limited to, MALIALIM (registered trademark) AAB-0851, MALIALIM AFB-1521, MALIALIM AKM- 0531, MALIALIM AWS-0851, MALIALIM HKM-50A, MALIALIM SC-0708A, MALIALIM SC-0505K, and MALIALIM SC-1015F (all manufactured by NOF Corp.), SN- DISPERSANT 5020, SN-DISPERSANT 5040, SN-DISPERSANT 5468, NOPCOSPERS 5600, and NOPCOSANT RFA (all manufactured by San Nopco Ltd.), SCONA (registered trademark) TSPP 10213GB, TSPP 22113GA, TSIN 4013 GC, TSPOE 1002 GBLL, DISPER (registered trademark) BYK108, and BYK-P105 (all manufactured by BYK-Chemie), and ISOBAM (registered trademark)-04, ISOB AM-06, and ISOBAM- 10 (all manufactured by Kuraray Co., Ltd.).FN202401504

[0035] < Binder >An insulating layer forming binder in the present disclosure preferably has a fluoroethylene group and a vinyl ether group.When the insulating layer forming binder includes the fluoroethylene group alone, the solubility in a solvent tends to be low, and the thixotropy tends to be high. Further, it is difficult to achieve a viscosity with which the liquid composition can be ejected by inkjet. Even if the viscosity is reduced by lowering the concentration of the solid content included in the liquid composition, there is a concern that unevenness may occur after the liquid composition is applied to the substrate, the application amount of the liquid composition is relatively increased, or the like.When the insulating layer forming binder in the present disclosure includes the fluoroethylene group and the vinyl ether group, the solubility in a general-purpose solvent such as an alcohol or an ether is improved. The thixotropy is accordingly reduced, thereby providing the liquid composition that can be stably discharged by inkjet. Further, when the insulating layer forming binder includes the fluoroethylene group in the resulting insulating layer, the battery stability can be improved.Note that the thixotropy is a property of a highly viscous fluid reversibly decreasing its viscosity when a force is applied to the highly viscous fluid.

[0036] A method for determining whether or not the insulating layer forming binder in the present disclosure includes the fluoroethylene group and the vinyl ether group is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, nuclear magnetic resonance (NMR) equipment and Fourier transform infrared spectroscopy (FT-IR). More specifically, a functional group can be identified by scraping off the insulating layer, immersing the scraped insulating layer in a solvent such as tetrahydrofuran (THF) to dissolve resin components, and then analyzing the resin components.

[0037] The weight average molecular weight (Mw) of the insulating layer forming binder in the present disclosure is 25,000 or more and 80,000 or less.When the weight average molecular weight (Mw) of the insulating layer forming binder is 25,000 or more, the liquid composition can have a suitable viscosity for inkjet ejection, and the insulating layer having sufficient strength can be obtained. Further, the resulting insulating layer is not dissolved in the electrolytic liquid even in an oxidized state, which is preferable.When the weight average molecular weight (Mw) of the insulating layer forming binder is 80,000 or less, the thixotropy of the liquid composition is reduced, and the liquid composition can be stably ejected by inkjet, thereby obtaining the uniform insulating layer.FN202401504

[0038] A method for measuring the weight average molecular weight (Mw) of the insulating layer forming binder is not particularly limited and 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 insulating layer forming binder can be measured by scraping off the insulating layer, immersing the scraped insulating layer in a solvent such as tetrahydrofuran (THF) to dissolve resin components, and then analyzing the resin components.

[0039] The content of the insulating layer forming binder is not particularly limited and can be appropriately selected depending on the purpose. However, the content is preferably 1% by mass or more and 5% by mass or less relative to the total amount of the insulating inorganic particles in the insulating layer.When the content of the insulating layer forming binder is 1% by mass or more relative to the total amount of the insulating inorganic particles in the insulating layer, the insulating layer having sufficient strength can be obtained.When the content of the insulating layer forming binder is 5% by mass or less relative to the total amount of the insulating inorganic particles in the insulating layer, the thixotropy can be reduced, the ejection properties by inkjet are improved, and the occurrence of nozzle clogging and ejection abnormalities (e.g., deformed ejection and abnormal ejection speed) can be prevented. The resulting insulating layer does not have problems such as a decrease in output due to an increase in battery resistance and a decrease in cycle characteristics, which is preferable. More specifically, when the content of the insulating layer forming binder is more than 5% by mass, there is a concern that a part of the insulating layer forming binder may dissolve into the electrolytic liquid, increasing the battery resistance and reducing the battery output. Further, this may accelerate deterioration of the battery performance in the cycle evaluation.

[0040] As the insulating layer forming binder, a suitably synthesized binder or a commercially available product may be used.Examples of the commercially available insulating layer forming binder product include, but are not limited to, by product name, LUMIFLON (registered trademark) LF200F (manufactured by AGC Inc.), ZEFFLE (registered trademark) GK570 (manufactured by Daikin Industries, Ltd.), and ZAFLON (registered trademark) GF-X-101 and GF-400 (manufactured by Toagosei Co., Ltd.).

[0041] The dispersant and the insulating layer forming binder are soluble in a non-polar solvent or a mixed liquid (mixed solvent) including a non-polar solvent. Note that the solubility of the resin in the non-polar solvent or the mixed liquid including the non-polar solvent is preferablyFN202401504 determined under conditions where the non-polar solvent or the mixed liquid including the non-polar solvent is in a liquid form. For example, the solubility in the mixed liquid including a polar solvent such as ethylene carbonate, in addition to dimethyl carbonate, ethyl methyl carbonate, and the non-polar solvent, which are non-aqueous electrolyte solvents, is preferably determined at 25°C and 1 atmospheric pressure.Note that, in the present specification, the non-polar solvent is a solvent having a bond dipole moment of 1.15 D or less. The solubility of the resin in the non-polar solvent or the mixed liquid including the non-polar solvent is preferable from the viewpoint of improving the thixotropy of the liquid composition.

[0042] Examples of the insulating layer forming binder that is soluble in the non-polar solvent include, but are not limited to, by product name, LUMIFLON (registered trademark) LF200F (manufactured by AGC Inc.), ZEFFEE (registered trademark) GK570 (manufactured by Daikin Industries, Ltd.), and ZAFLON (registered trademark) GF-X-101 and GF-400 (manufactured by Toagosei Co., Ltd.).Examples of the insulating layer forming binder that is not soluble in the non-polar solvent include, but are not limited to, by product name, KF POLYMER (registered trademark) #850, W#1100, and W#9100 (manufactured by Kureha Corp.), and SOLEF (registered trademark) 5130 (manufactured by Solvay).

[0043] The ratio of the dispersant and the insulating layer forming binder (dispersant: insulating layer forming binder) is not particularly limited and can be appropriately selected depending on the purpose. However, the ratio is preferably 3:1 to 3:15.When the ratio of the dispersant and the insulating layer forming binder is 3:1 or more, the resulting insulating layer is not dissolved in the electrolytic liquid, which is preferable.When the ratio of the dispersant and the insulating layer forming binder is 3:15 or less, the ejection properties by inkjet are improved, and the occurrence of nozzle clogging and ejection abnormalities can be prevented.The dispersant and the insulating layer forming binder can be dissolved alone in the non-polar solvent or the mixed liquid including the non-polar solvent. However, when the dispersant and the insulating layer forming binder are combined in the above-mentioned ratio, the insulating layer with excellent film strength after cycle test can be formed.

[0044] <Solvent>The insulating layer forming liquid composition according to embodiments of the present invention may include a solvent.The solvent is not particularly limited and can be appropriately selected depending on the purpose, as long as it can disperse the insulating inorganic particles. Examples of the solventFN202401504 include, but are not limited to, water, a hydrocarbon solvent, an alcohol solvent, a ketone solvent, an ester solvent, and an ether solvent.Specific examples of the solvent include, but are not limited to, water, N-methyl-2- pyrrolidone, dimethyl sulfoxide, ethyl lactate, methyl ethyl ketone, 2-heptanone, diacetone alcohol, isopropyl alcohol, diisobutyl ketone, cyclohexanone, butyl acetate, isopropyl glycol, propylene glycol, ethylene glycol, hexylene glycol, l-propoxy-2-propanol, 2-pyrrolidone, triethylene glycol, diethylene glycol, diethylene glycol monomethyl ether, and diethylene glycol monoethyl ether.These solvents may be used alone or in combination of two or more types.

[0045] The content of the solvent is not particularly limited and can be appropriately selected depending on the purpose. For example, the content can be 40% by mass or more and 70% by mass or less relative to the total amount of the liquid composition.

[0046] < Other components >The insulating layer forming liquid composition according to embodiments of the present invention may include an additive such as a surfactant, a pH adjuster, a rust inhibitor, a preservative, a fungicide, an antioxidant, a reduction inhibitor, an evaporation promoter, and a chelating agent as other components.The contents of the other components are not particularly limited and can be appropriately set depending on the contents of the various components in the liquid composition.

[0047] [Viscosity]The viscosity of the insulating layer forming liquid composition according to embodiments of the present invention is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of improving the ejection properties by inkjet, the viscosity is preferably 5.0 mPa- s or more and 30 mPa- s or less.

[0048] In the insulating layer forming liquid composition according to embodiments of the present invention, when the viscosity measured using an E-type viscometer at 100 rpm is defined as a viscosity A, and the viscosity measured using an E-type viscometer at 10 rpm is defined as a viscosity B, it is preferable that a ratio [B / A] of the viscosity B relative to the viscosity A is 0.95 or more and 1.05 or less. When the ratio [B / A] of the viscosity B relative to the viscosity A is 0.95 or more and 1.05 or less, the thixotropy of the liquid composition is low.When the ratio [B / A] of the viscosity B relative to the viscosity A is 0.95 or more and 1.05 or less, ejection abnormalities do not occur even in the continuous ejection by ink jet, allowing the stable ejection. Further, this can eliminate problems such as nozzle clogging and ejection abnormalities in the continuous ejection due to deformed ejection and abnormal ejection speed.FN202401504

[0049] A method for measuring the viscosity of the insulating layer forming liquid composition according to embodiments of the present invention is not particularly limited and can be selected appropriately depending on the purpose. For example, the viscosity can be measured using an E-type viscometer (TVE-25L manufactured by Tokisangyo) with a standard rotor 1°34’ *R24 or the like.

[0050] [Surface tension]The surface tension of the insulating layer forming liquid composition according to embodiments of the present invention is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of improving the ejection properties by inkjet, the surface tension is preferably 15 mN / m or more and 40 mN / m or less.

[0051] <Method for producing insulating layer forming liquid composition>A method for producing the insulating layer forming liquid composition according to embodiments of the present invention is not particularly limited and can be appropriately selected depending on the purpose. For example, the liquid composition can be obtained by adding and dispersing a solvent B in which the insulating layer forming binder and other components are dissolved into a dispersion liquid in which the insulating inorganic particles and the dispersant are dispersed in a solvent A. Note that the solvent A and the solvent B may be the same or different.The dispersion liquid may be prepared using a dispersing machine after the solvent, the insulating inorganic particles, and the dispersant are pre-stirred. The dispersing machine is not particularly limited and can be appropriately selected depending on the purpose. Examples of the dispersing machine include, but are not limited to, a homomixer, a homogenizer, an ultrasonic dispersing machine, a ball mill, a bead mill, and a cavitation mill.

[0052] (Electrode)An electrode according to embodiments of the present invention includes a substrate, an electrode composite layer disposed on a part of the substrate, and the insulating layer covering a boundary between a substrate exposed portion where the substrate is exposed and the electrode composite layer. The insulating layer includes the insulating inorganic particles, the dispersant, and the binder. The dispersant includes at least one selected from a structural unit represented by the general formula (1), a structural unit represented by the general formula (2), and a structural unit represented by the general formula (3). The weight average molecular weight of the binder is 25,000 or more and 80,000 or less.Note that the insulating layer in the electrode according to embodiments of the present invention is formed using the insulating layer forming liquid composition according to embodiments of the present invention. Thus, descriptions overlapping with those in theFN202401504 section “(Insulating layer forming liquid composition)” in the present specification are omitted.

[0053] [Chemical 4]... General Formula (1)

[0054] [... General Formula (2)

[0055] [Chemical 6]... General Formula (3)In the general formulas (1) to (3), * represents a bonding site to an adjacent main chain structural unit, and M represents an ammonium salt.

[0056] Here, embodiments of the present invention are described with reference to the drawings.However, the present invention is not limited to these embodiments.Note that, in each drawing, identical or similar constituent components are denoted by identical or similar reference numerals, and duplicated descriptions thereof are omitted. Further, the number, position, shape, and the like of the constituent members are not limitedFN202401504 to the these embodiments, and may be the number, position, shape, and the like that are preferable for implementing embodiments of the present invention.

[0057] [FIG. 1]FIG. 1 is a schematic cross-sectional view of an electrode according to an embodiment of the present invention.An electrode 100 includes a substrate 1, an electrode composite layer 2 disposed on a part of the substrate 1, and an insulating layer 3. The insulating layer 3 is disposed at a boundary between a substrate exposed portion 11 where the substrate 1 is exposed and the electrode composite layer 2.Note that FIG. 1 illustrates a configuration in which the electrode composite layer 2 and the insulating layer 3 are disposed on one surface of the substrate 1. However, the electrode composite layer 2 and the insulating resin layer 3 may be disposed on both opposite surfaces of the substrate 1.

[0058] <Substrate>The substrate is not particularly limited and can be appropriately selected depending on the purpose, as long as the substrate has electronic conductivity and is stable to the applied potential. Examples of the substrate include, but are not limited to, an aluminum foil, a copper foil, a stainless steel foil, a titanium foil, etched foils in which these foils are etched to form fine holes, a carbon-coated foil in which the surface is coated with a carbon-containing resin layer, and a perforated substrate used in a lithium ion capacitor.

[0059] <Electrode composite layer>The electrode composite layer is disposed on a part of the substrate. In other words, the electrode composite layer is formed so as to produce the substrate exposed portion where the electrode composite layer is not disposed for the purpose of providing the insulating layer or welding a lead.The electrode composite layer (also referred to as “active material layer”) is composed mainly of an active material (a negative electrode active material or a positive electrode active material). Note that, in the present specification, the term “mainly composed of an active material” means that the content of the active material is 70% by mass or more relative to the entire electrode composite layer.

[0060] The electrode composite layer is not particularly limited and can be appropriately selected depending on the purpose. For example, the electrode composite layer includes the active material (a negative electrode active material or a positive electrode active material) and may include a conductive assistant, an electrode composite layer forming binder, an electrode composite layer forming dispersant, a solid electrolyte, and other components as necessary.FN202401504

[0061] [FIG. 2A and FIG. 2B]FIG. 2A is a schematic cross-sectional view of an electrode according to an embodiment of the present invention. FIG. 2B is a schematic cross-sectional view of an electrode according to an embodiment of the present invention.As illustrated in FIG. 2A, the electrode composite layer may include an opening 21. The number of openings 21 is preferably one or more, more preferably two or more.The opening 21 may penetrate the electrode composite layer from the surface of the electrode composite layer to the surface of the substrate, or may not penetrate to the surface of the substrate.The opening 21 may be hollow or filled with a material 22. When the opening 21 is filled with the material 22, the material 22 may be a single material or a mixture of two or more materials. However, in either case, the material 22 is different in quality from the material constituting the electrode composite layer. From the viewpoint of improving ion conductivity, the material 22 is preferably a material including a solid electrolyte.The electrode composite layer including the openings 21 can be suitably produced by using inkjet as an electrode composite layer forming means by reason of easy application control.

[0062] As illustrated in FIG. 2B, an adhesive layer 23 may be disposed between the substrate 1 and the electrode composite layer 2, the adhesive layer 23 including metal that alloys with lithium. Note that, when the adhesive layer 23 is disposed between the substrate 1 and the electrode composite layer 2, a boundary between the adhesive layer 23 and the substrate exposed portion 11 is defined as the boundary in the present disclosure.

[0063] << Active material > >A positive electrode active material or a negative electrode active material can be used as the active material. Note that the positive electrode active material or the negative electrode active material may be used alone or in combination of two or more types.

[0064] -Positive electrode active material-The positive electrode active material is not particularly limited as long as it is a material that can reversibly absorb and release an alkali metal ion. However, an alkali metal-containing transition metal compound can be used.Examples of the alkali metal-containing transition metal compound include, but are not limited to, a lithium-containing transition metal compound such as a composite oxide including one or more elements selected from the group consisting of cobalt, manganese, nickel, chromium, iron, and vanadium, and lithium.Examples of the lithium-containing transition metal compound include, but are not limited to, lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide.FN202401504

[0065] As the alkali metal-containing transition metal compound, a polyanion-based compound having an XO4 tetrahedron (X=P, S, As, Mo, W, Si, etc.) in the crystal structure can be used. Of these, from the viewpoint of cycle characteristics, a lithium-containing transition metal phosphate compound such as lithium iron phosphate or lithium vanadium phosphate is preferable, and from the viewpoint of lithium diffusion coefficient and output characteristics, lithium vanadium phosphate is more preferable.Note that, when a polyanion compound is used, it is preferable that the surface of the compound is coated with a conductive assistant such as a carbon material to form a composite from the viewpoint of electronic conductivity.

[0066] It is preferable that at least a part of the surface of the alkali metal-containing transition metal compound is coated with an ion-conductive oxide. The ion-conductive oxide is preferably a lithium ion-conductive oxide.The lithium ion-conductive oxide is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, an oxide represented by the general formula LixAOy(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 the lithium ion-conductive oxide include, but are not limited to, LisBOs, LiBCh, Li2CO3, LiAlCE, Li4SiO4, Li2SiO3, LisPCE, Li2SO4, Li2TiO3, Li4TisOi2, Li2Ti20s, Li2ZrO3, LiNbOs, LiTaOs, Li2MoO4, and Li2WO4. Of these, Li4TisOi2, Li2ZrO3, or LiNbOs is preferable.Further, the lithium ion-conductive oxide may be a composite oxide. As the composite oxide, any combination of the lithium ion-conductive oxides can be used, and examples thereof include, but are not limited to, Li4SiO4-Li3BO3 and Li4SiO4-Li3PO4.

[0067] -Negative electrode active material-The negative 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 an alkali metal ion. For example, a carbon material including graphite with a graphitetype crystal structure can be used.Examples of the carbon material include, but are not limited to, natural graphite, spherical or fibrous artificial graphite, non-graphitizable carbon (hard carbon), and easily graphitizable carbon (soft carbon).Examples of the material other than the carbon material include, but are not limited to, lithium titanate and titanium oxide.From the viewpoint of increasing the energy density of a lithium ion battery, a high capacity material such as silicon, tin, a silicon alloy, a tin alloy, silicon oxide, silicon nitride, or tin oxide can also be suitably used as the negative electrode active material.FN202401504

[0068] <<Conductive assistantsThe conductive assistant is not particularly limited and can be selected appropriately according to the purpose. For example, carbon black produced by a furnace method, an acetylene method, a gasification method, or the like, and a carbon material such as a carbon nanofiber, a carbon nanotube, graphene, or graphite particles can be used.As the conductive assistant other than the carbon material, for example, particles of metal such as aluminum, a metal fiber, or the like can be used. Note that the conductive assistant may be previously compounded with the active material.

[0069] The content of the conductive assistant relative to the active material is not particularly limited and can be appropriately set depending on the purpose. However, the content is preferably 10% by mass or less, more preferably 8% by mass or less.When the content of the conductive assistant relative to the active material is 10% by mass or less, the stability of the electrode composite layer forming liquid composition is improved, which is preferable.When the content of the conductive assistant relative to the active material is 8% by mass or less, the stability of the electrode composite layer forming liquid composition is further improved, which is preferable.

[0070] <<Electrode composite layer forming binder>>The electrode composite layer forming binder is not particularly limited and can be appropriately selected depending on the purpose, as long as it can bond the negative electrode materials together, the positive electrode materials together, the negative electrode material and the negative electrode substrate, and the positive electrode material and the positive electrode substrate. Note that, when the electrode composite layer forming liquid composition is used for inkjet ejection, from the viewpoint of preventing nozzle clogging of the liquid ejection head, it is preferable that the electrode composite layer forming binder does not easily increase the viscosity of the electrode composite layer forming liquid composition. Note that, in the present specification, a distinction is made between the “binder” or “insulating layer forming binder” in the insulating layer forming liquid composition and the “electrode composite layer forming binder” in the electrode composite layer forming liquid composition.

[0071] As the electrode composite layer forming binder, a polymer compound can be used. Examples of the polymer compound include, but are not limited to, a thermoplastic resin such as poly vinylidene fluoride (PVDF), an acrylic resin, polyethylene, polypropylene, polyurethane, nylon, polytetrafluoroethylene, polyphenylene sulfide, polyethylene terephthalate, or polybutylene terephthalate, a polyamide compound, a polyimide compound,FN202401504 polyamide imide, ethylene-propylene-butadiene rubber (EPBR), styrene-butadiene rubber (SBR), nitrile butadiene rubber (NBR), isoprene rubber, polyisobutene, polyethylene glycol (PEO), polymethyl methacrylate (PMMA), and polyethylene vinyl acetate (PEVA).

[0072] The content of the electrode composite layer forming binder relative to the active material is not particularly limited and can be appropriately set depending on the purpose. However, the content is preferably 1% by mass or more and 15% by mass or less, more preferably 3% by mass or more and 10% by mass or less. When the content of the electrode composite layer forming binder relative to the active material is 1% by mass or more, the active material can be firmly bonded to the substrate, which is preferable.

[0073] <<Electrode composite layer forming dispersant>>The electrode composite layer forming dispersant is not particularly limited as long as it can improve the dispersibility of the active material in the electrode composite layer forming liquid composition. Examples of the dispersant include: a high molecular weight dispersant such as a polyethylene oxide-based, polypropylene oxide -based, polycarboxylic acid-based, naphthalene sulfonic acid formaldehyde condensate -based, polyethylene glycol-based, polycarboxylic acid partial alkyl ester-based, poly ether-based, or polyalkylene polyamine- based dispersant; a low molecular weight dispersant such as an alkylsulfonic acid-based, quaternary ammonium-based, higher alcohol alkylene oxide-based, polyhydric alcohol ester- based, or alkyl polyamine-based dispersant; and an inorganic dispersant such as a polyphosphate-based dispersant.Note that, in the present specification, a distinction is made between the “dispersant having a carboxyl group or an acid anhydride group” in the insulating layer forming liquid composition and the “electrode composite layer forming dispersant” in the electrode composite layer forming liquid composition.

[0074] < < S olid electrolyte > >The solid electrolyte is not particularly limited as long as it is a solid substance that exhibits electronic insulation and ion conductivity. However, from the viewpoint of exhibiting high ion conductivity, a sulfide solid electrolyte and an oxide solid electrolyte are preferable.

[0075] Examples of the sulfide solid electrolyte include, but are not limited to, LiioGeP2Si2 and LiePSsX (X=F, Cl, Br, I) having an argyrodite crystal structure.Examples of the oxide-based solid electrolyte include, but are not limited to, LLZ (LiyLasZnOn) having a garnet-type crystal structure, LATP (Lii+xAlxTi20x(PO4)3) (0.1^x^0.4) having a NASICON-type crystal structure, LLT (LiojsLao.ssTiOs) having a perovskite-type crystal structure, and amorphous LIPON (Li2.9P03.3No.4).These solid electrolytes may be used alone or in combination of two or more types.FN202401504

[0076] When the electrode composite layer is a positive electrode composite layer, the average thickness of the positive electrode composite layer is not particularly limited and can be appropriately selected depending on the purpose. However, the average thickness is preferably 10 pm or more and 300 pm or less, more preferably 40 pm or more and 150 pm or less.When the average thickness of the positive electrode composite layer is 10 pm or more, the energy density of the electrochemical element is improved.When the average thickness of the negative electrode composite layer is 300 pm or less, the load characteristics of the electrochemical element are improved.

[0077] When the electrode composite layer is a negative electrode composite layer, the average thickness of the negative electrode composite layer is not particularly limited and can be appropriately selected depending on the purpose. However, the average thickness is preferably 10 pm or more and 450 pm or less, more preferably 20 pm or more and 100 pm or less.When the negative electrode composite layer has the average thickness of 10 pm or more, the energy density of the electrochemical element is improved.When the negative electrode composite layer has the average thickness of 450 pm or less, the cycle characteristics of the electrochemical element are improved.

[0078] The electrode composite layer may be formed on both sides of the substrate (positive electrode substrate and / or negative electrode substrate). Note that the electrodes may be laminated in multiple layers to increase the charge / discharge capacity of the electrodes. The number of layers of the positive electrodes or the negative electrodes is not particularly limited and can be increased as necessary.

[0079] < Insulating lay er >The insulating layer in the electrode according to embodiments of the present invention is disposed so as to cover the boundary between the substrate exposed portion 11 where the substrate is exposed and the electrode composite layer 2.

[0080] [FIG. 3A and FIG. 3B]FIG. 3A is a schematic cross-sectional view of an electrode according to an embodiment of the present invention. FIG. 3B is a schematic cross-sectional view of an electrode according to an embodiment of the present invention.As illustrated in FIG. 3A, the insulating layer 3 may be disposed at the boundary portion and at the end of the electrode composite layer 2. As illustrated in FIG. 3B, the insulating layer 3FN202401504 may be disposed at the boundary portion and on the upper surface of the electrode composite layer 2.When the insulating layer 3 is disposed on the upper surface of the electrode composite layer 2, the coverage of the upper surface of the electrode composite layer 2 with the insulating layer 3 is preferably 90% or more, more preferably 95% or more, even more preferably 100%. In other words, when the insulating layer 3 is disposed on the upper surface of the electrode composite layer 2, an exposed region that is not covered by the insulating layer 3 may exist on the upper surface of the electrode composite layer 2.In the aspect in which the insulating layer 3 is disposed on the electrode composite layer 2, the insulating layer can be formed thinly and uniformity as a film when applied by inkjet, improving stability of the battery.

[0081] The average thickness of the insulating layer is not particularly limited and can be appropriately selected depending on the purpose. However, the average thickness is preferably 2 pm or more and 20 pm or less, more preferably 5 pm or more and 10 pm or less. When the average thickness of the insulating layer is 2 pm or more, sufficient insulation is obtained, which is preferable.When the average thickness of the insulating layer is 20 pm or less, problems can be eliminated that may occur when the liquid composition is applied, such as damage to the electrode mixture layer due to the weight of the liquid composition itself, the occurrence of unevenness due to flowing of the liquid composition, and the liquid composition permeating into the substrate.

[0082] A method for measuring the average thickness of the insulating layer is not particularly limited and can be appropriately selected depending on the purpose. For example, the average thickness can be measured using a DIGIMATIC micrometer (manufactured by Mitutoyo Corp.).

[0083] The peel strength of the insulating layer from the substrate is not particularly limited and can be appropriately selected depending on the purpose. However, the peel strength is preferably 50 N / m or more.When the peel strength of the insulating layer from the substrate is 50 N / m or more, some of the insulating inorganic particles included in the insulating layer can be prevented from falling off due to friction or the like when the electrode is formed with a roll-to-roll method or transported. In addition, the battery characteristics can be prevented from being adversely affected.

[0084] FN202401504A method for measuring the peel strength of the insulating layer from the substrate is not particularly limited and can be appropriately selected depending on the purpose. One example of the method is described below.[Method for measuring peel strength]As an evaluation device, for example, a light-load type adhesive / film peeling analyzer (VPA- 3S manufactured by Kyowa Interface Science Co., Ltd.) is used with an 8 mm wide tape (cellophane tape manufactured by Nittosha Co., Ltd.). The tape is attached onto the insulating layer, and the peeling operation is performed at a peel angle of 90 degrees and a speed of 30 mm / min. The load applied to the load cell during this operation is taken as the peel strength.

[0085] The width of the insulating layer is not particularly limited and can be appropriately selected depending on the battery configuration. However, the width is preferably 2 mm or more and 30 mm or less.Note that the term “width” of the insulating layer refers to the distance (in the length direction of the electrode) from one end to the other end on the upper surface of the insulating layer, facing the substrate surface in contact with the electrode composite layer, in a cross-sectional view taken in the thickness direction of the electrode and a direction parallel to the length direction of the electrode.When the width of the insulating layer is 2 mm or more, a problem can be eliminated such as the one in that it becomes difficult for the insulating layer to follow the meandering of the electrode composite layer and cover the substrate exposed portion.When the width of the insulating layer is 30 mm or less, a problem can be eliminated such as the one in that the insulating layer interferes with the lead welding or the one in that the battery size becomes excessively large compared to the battery capacity.

[0086] The covering width of the insulating layer over the electrode composite layer is not particularly limited and can be appropriately selected depending on the purpose. However, the covering width is preferably 0.1 mm or more and 5 mm or less.Note that, in the present specification, the term “covering width” refers to the distance (in the length direction of the electrode) from one end to the other end on the surface where the electrode composite layer contacts the insulating layer, facing the substrate surface in contact with the electrode composite layer, in a cross-sectional view taken in the thickness direction of the electrode and a direction parallel to the length direction of the electrode.When the cover width is 0.1 mm or more, a problem can be eliminated such as the one in that it becomes difficult for the insulating layer to follow the meandering of the electrode composite layer and cover the substrate exposed portion.When the covering width is 5 mm or less, the insulating layer can be prevented from adversely affecting the battery capacity.

[0087] FN202401504The electrode composite layer 2 and the insulating layer 3 may be adhered to each other with an adhesive. In other words, the electrode composite layer 2 and the insulating layer 3 may be adhered to each other via an adhesive layer derived from the adhesive.

[0088] The adhesive is not particularly limited and can be appropriately selected depending on the purpose. However, it is preferable that the adhesive is at least one selected from acrylate and poly vinylidene fluoride (PVDF).

[0089] The adhesive is preferably applied by an inkjet method so that the adhesive can be applied precisely in a desired shape.

[0090] (Electrode manufacturing apparatus)An electrode manufacturing apparatus according to embodiments of the present invention includes a storage container and an insulating layer forming liquid composition applying means, and may include an electrode composite layer forming means, an insulating layer forming liquid composition heating means, and other means, as necessary.An electrode manufacturing method according to embodiments of the present invention may include an electrode composite layer forming step, an insulating layer forming step, and other steps.

[0091] < Storage container >The storage container includes the insulating layer forming liquid composition and a container. In the storage container, the insulating layer forming liquid composition is stored in the container.Examples of the container include, but are not limited to, a glass bottle, a plastic container, a plastic bottle, a stainless steel bottle, an 18-liter can, and an oil drum.

[0092] <Electrode composite layer forming step and electrode composite layer forming means>The electrode composite layer forming step is a step of forming the electrode composite layer on a part of the substrate. The electrode composite layer forming step preferably includes an electrode composite layer forming liquid composition applying step and an electrode composite layer forming liquid composition heating step.The electrode composite layer forming means is a means for forming the electrode composite layer on a part of the substrate. The electrode composite layer forming means preferably includes an electrode composite layer forming liquid composition applying means and an electrode composite layer forming liquid composition heating means.The electrode composite layer forming step can be suitably performed by the electrode composite layer forming means.

[0093] FN202401504<<Electrode composite layer forming liquid composition applying step and electrode composite layer forming liquid composition applying means>>The electrode composite layer forming liquid composition applying step is a step of applying the electrode composite layer forming liquid composition to a part of the substrate.The electrode composite layer forming liquid composition applying means is a means for applying the electrode composite layer forming liquid composition to a part of the substrate. The electrode composite layer forming liquid composition applying step can be suitably performed by the electrode composite layer forming liquid composition applying means.

[0094] When the positive electrode is produced, the electrode composite layer forming liquid composition (positive electrode composite layer forming liquid composition) is applied onto a part of a positive electrode substrate to form a positive electrode composite layer.When the negative electrode is produced, the electrode composite layer forming liquid composition (negative electrode composite layer forming liquid composition) is applied onto a part of a negative electrode substrate to form a negative electrode composite layer.

[0095] The electrode composite layer forming liquid composition applying means is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, a comma coater method, a die coater method, a curtain coat method, a spray coat method, and a liquid ejection method (an inkjet method or an IJ method).

[0096] <<Electrode composite layer forming liquid composition heating step and electrode composite layer forming liquid composition heating means>>The electrode composite layer forming liquid composition heating step is a step of heating the electrode composite layer forming liquid composition applied onto the substrate.The electrode composite layer forming liquid composition heating means is a means for heating the electrode composite layer forming liquid composition applied onto the substrate. The electrode composite layer forming liquid composition heating step can be suitably performed by the electrode composite layer forming liquid composition heating means.

[0097] The electrode composite layer forming liquid composition heating means (step) is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, a method of heating the coated surface with a resistance heater, an infrared heater, a fan heater, or the like, and a method of drying the backside of the coated surface with a hot plate, a drum heater, or the like.From the viewpoint of uniformly heating and drying the coated surface, a resistance heater, an infrared heater, and a fan heater capable of drying the coated surface without contact are preferable.FN202401504These heating mechanisms may be used alone or in combination of two or more types.

[0098] A heating temperature in the electrode composite layer forming liquid composition heating step is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of protecting the substrate and the active material of the electrode composite layer, the heating temperature is preferably 70°C or higher and 150°C or lower.

[0099] < Insulating layer forming step and insulating layer forming means >The insulating layer forming step is a step of forming the insulating layer so as to cover the boundary between the substrate exposed portion in which the substrate is exposed and the electrode composite layer. The insulating layer forming step preferably includes an insulating layer forming liquid composition applying step and an insulating layer forming liquid composition heating step.The insulating layer forming means is a means for forming the insulating layer so as to cover the boundary between the substrate exposed portion in which the substrate is exposed and the electrode composite layer. The insulating layer forming means preferably includes an insulating layer forming liquid composition applying means and an insulating layer forming liquid composition heating means.The insulating layer forming step can be suitably performed by the insulating layer forming means.

[0100] <<Insulating layer forming liquid composition applying step and insulating layer forming liquid composition applying means >>The insulating layer forming liquid composition applying step is a step of applying the insulating layer forming liquid composition to the boundary between the substrate exposed portion in which the substrate is exposed and the electrode composite layer.The insulating layer forming liquid composition applying means is a means for applying the insulating layer forming liquid composition to the boundary between the substrate exposed portion in which the substrate is exposed and the electrode composite layer.The insulating layer forming liquid composition applying step can be suitably performed by the insulating layer forming liquid composition applying means.

[0101] As the insulating layer forming liquid composition applying means, a liquid ejection method such as an inkjet method that allows non-contact and on-demand application is preferable.

[0102] <<Insulating layer forming liquid composition heating step and insulating layer forming liquid composition heating means >>The insulating layer forming liquid composition heating step is a step of heating the insulating layer forming liquid composition which has been applied.FN202401504The insulating layer forming liquid composition heating means is a means for heating the insulating layer forming liquid composition which has been applied.The insulating layer forming liquid composition heating step can be suitably performed by the insulating layer forming liquid composition heating means.

[0103] The insulating layer forming liquid composition heating means (step) is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, a method of heating the coated surface with a resistance heater, an infrared heater, a fan heater, or the like, and a method of drying the back side of the coated surface with a hot plate, a drum heater, or the like. From the viewpoint of uniformly heating and drying the coated surface, a resistance heater, an infrared heater, and a fan heater that can dry the coated surface without contact is preferable.These heating mechanisms may be used alone or in combination of two or more types.

[0104] A heating temperature in the insulating layer forming liquid composition heating step is not particularly limited and can be selected appropriately depending on the purpose. From the viewpoint of protecting the substrate and the active material of the electrode composite layer, the heating temperature is preferably 70°C or higher and 150°C or lower.When the heating temperature in the insulating layer forming liquid composition heating step is 70°C or higher, the strength of the insulating layer is improved, which is preferable.When the heating temperature in the insulating layer forming liquid composition heating step is 150°C or lower, bubbles due to bumping on the insulating layer surface can be prevented, which is preferable.

[0105] <Other steps and other means>The other steps are not particularly limited and can be appropriately selected according to the purpose. Examples thereof include, but are not limited to, a step of forming an adhesive layer between the substrate and the electrode composite layer, an opening forming step of forming an opening of a desired size in the electrode composite layer, a solid electrolyte filling step of filling the opening with a solid electrolyte, a step of forming an adhesive layer between the electrode composite layer and the insulating layer, and a cutting step of cutting the electrode to a desired size by punching or the like.The other means are not particularly limited and can be appropriately selected according to the purpose. Examples thereof include a means for forming an adhesive layer between the substrate and the electrode composite layer, an opening forming means for forming an opening of a desired size in the electrode composite layer, a solid electrolyte filling means for filling the opening with a solid electrolyte, a means for forming an adhesive layer between the electrode composite layer and the insulating layer, and a cutting means for cutting the electrode to a desired size by punching or the like.FN202401504The other steps can be suitably performed by the other means.

[0106] An electrode manufacturing apparatus according to embodiments of the present invention is described with reference to the drawings. However, the present invention is not limited to these embodiments.Note that, in each drawing, identical or similar constituent components are denoted by identical or similar reference numerals, and duplicated description thereof may be omitted. Further, the number, position, shape, and the like of the constituent members are not limited to these embodiments, and may be the number, position, shape, and the like that are preferable for implementing the present invention.

[0107] [FIG. 4]FIG. 4 is a schematic diagram illustrating an electrode manufacturing apparatus according to an embodiment of the present invention.A liquid ejection device 300 illustrated in FIG. 4 ejects an insulating layer forming liquid composition 130A onto an electrode element 140 in which a negative electrode composite layer 120 is disposed on a negative electrode substrate 110. The insulating layer forming liquid composition 130A is stored in a tank 307 and supplied from the tank 307 to a liquid ejection head 306 via a tube 308.

[0108] The liquid ejection device 300 may be provided with a mechanism for capping a nozzle of the liquid ejection head 306 to prevent the insulating layer forming liquid composition 130A from being dried when it is not ejected from the liquid ejection head 306.

[0109] When a negative electrode is produced, the electrode element 140 is placed on a heatable stage 200, and then droplets of the insulating layer forming liquid composition 130A are ejected onto the electrode element 140, followed by heating. In this operation, the stage 200 may be moved, or the liquid ejection head 306 may be moved.The insulating layer forming liquid composition 130A ejected onto the electrode element 140 may be heated by the stage 200 or by a heating mechanism other than the stage 200.

[0110] There are no particular limitations on the heating temperature as long as it is a temperature at which the dispersion medium can be volatilized. However, from the viewpoint of power consumption, the heating temperature is preferably in a range of 70°C to 150°C.The insulating layer forming liquid composition 130A ejected onto the electrode element 140 may be heated by irradiation of ultraviolet light.As a result, an electrode (negative electrode) 400 in which an insulating layer 130 is formed on the electrode element 140 is obtained.

[0111] FN202401504Note that, in the present embodiment, the insulating layer 130 is formed on the electrode element 140 in which the negative electrode composite layer 120 is previously disposed on the negative electrode substrate 110. However, the negative electrode composite layer 120 may be formed on the negative electrode substrate 110 on the same line as that of the apparatus illustrated in FIG. 4. The electrode element 140 thus formed may be used for forming the insulating layer 130 thereon.

[0112] [FIG. 5]FIG. 5 is a schematic diagram illustrating an electrochemical element according to an embodiment of the present invention.In FIG. 5, an electrochemical element 700 is illustrated in which a positive electrode 500, including a positive electrode composite layer 502 and an insulating layer 13 disposed on a positive electrode substrate 501, and a negative electrode 400, including a negative electrode composite layer 402 and an insulating layer 13 disposed on a negative electrode substrate 401, are disposed as opposed electrodes via a separator 600. A treatment liquid 7 (e.g., a solution including a non-aqueous solvent and an electrolyte) is stored in a liquid bath 6, and the electrochemical element 700 is immersed in the treatment liquid 7. In this state, a voltage may be applied to the electrochemical element 700.Note that the insulating layer 13 may be formed on at least one of the negative electrode 400 and the positive electrode 500, or may be formed on both of them.

[0113] The electrochemical element 700 may be mounted in a portable device and the like. In the present specification, a product in which the electrochemical element 700 is mounted may be referred to as a mounted product.The electrochemical element 700 and a base material part of the mounted product in which the electrochemical element 700 is provided may be adhered with an adhesive. In other words, the electrochemical element 700 and the base material part of the mounted product in which the electrochemical element 700 is provided may be adhered via an adhesive layer derived from the adhesive.

[0114] The number of the electrochemical elements 700 mounted in the mounted product is not particularly limited and can be appropriately selected according to the purpose. However, the number is preferably more than one. In the mounted product in which a plurality of electrochemical elements 700 are mounted, it is preferable that at least two electrochemical elements 700 are bonded to form an L-shape and disposed on the base material of the mounted product. Note that it is preferable that a bonding region where at least two electrochemical elements 700 are bonded to each other does not overlap with an adhering region where the electrochemical elements 700 and the mounted product are adhered to each other with an adhesive.FN202401504

[0115] The adhesive is not particularly limited and can be appropriately selected depending on the purpose.

[0116] The mounted product may include other members different from the electrochemical element 700 in a region different from the region where the electrochemical elements 700 is adhered. The other members are not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, a heat exhaust member including a heat exhaust fan, and a heat exhaust pipe.

[0117] The mounted product and the other members may be adhered to each other with an adhesive. For example, when the mounted product and the other members are fixed to each other with a screw or the like, there is a risk that the fixed position may shift due to loosening of the screw. When the adhesive is used for adhering, the electrochemical element and the heat exhaust member can be fixed in predetermined positions. Further, such fixing is resistant to vibration, thus heat generated when the mounted product (e.g., a portable device, etc.) is operated using the energy of the electrochemical element can be efficiently and reliably exhausted.

[0118] When the electrochemical element 700 and the other members are mounted in the mounted product, the adhesive is preferably applied by an inkjet method as this allows the adhesive to be applied precisely in a desired shape. When the adhesive is applied by the inkjet method, from the viewpoint of productivity, it is preferable that the adhesive is applied to an adhering part between the electrochemical element 700 and the mounted product and adhering parts between the other members and the mounted product with a single scan of the inkjet head.

[0119] (Electricity storage device)An electricity storage device according to embodiments of the present invention includes an electrode.Note that the electrode that can be used is the same as that described in the “(Electrode)” section of the present specification, thus redundant description thereof is omitted.

[0120] An electricity storage device according to embodiments of the present invention is described with reference to the drawings.However, the present invention is not limited to these embodiments.Note that, in each drawing, identical or similar constituent components are denoted by identical or similar reference numerals, and duplicated description thereof may be omitted. Further, the number, position, shape, and the like of the constituent members are not limited to these embodiments, and may be the number, position, shape, and the like that are preferable for implementing the present invention.FN202401504

[0121] [FIG. 6]FIG. 6 is a schematic diagram illustrating an electricity storage device according to an embodiment of the present invention.In an electricity storage device 800, an electrolyte layer 51 constituted with a non-aqueous electrolyte is formed on a laminated electrode 40, and is sealed with an exterior case 52. In the electricity storage device 800, lead wires 41 and 42 are led out to the outside of the exterior case 52.In the laminated electrode 40, a negative electrode 400 and a positive electrode 500 are laminated via a separator 600. The positive electrodes 500 are laminated on both sides of the negative electrode 400. Further, the lead wire 41 is connected to a negative electrode substrate 401, and the lead wire 42 is connected to a positive electrode substrate 501.The negative electrode 400 has a negative electrode composite layer 402 and the insulating layer 13 sequentially formed on both sides of the negative electrode substrate 401.The positive electrode 500 has a positive electrode composite layer 502 and the insulating layer 13 sequentially formed on both sides of the positive electrode substrate 501.Note that the number of the negative electrodes 400 and the number of the positive electrodes 500 in the laminated electrode 40 may be the same or different.Note that the insulating layers 13 may be formed on at least one of the negative electrodes 400 and the positive electrodes 500, or on both.

[0122] The shape of the electricity storage device using the electrodes is not particularly limited, and examples thereof include, but are not limited to, a laminate type in which flat electrodes are laminated, a cylinder type in which sheet electrodes and separators are spirally wound, a cylinder type with an inside-out structure that combines pellet electrodes and separators, and a coin type in which pellet electrodes and separators are laminated.The electricity storage device 800 may include other members as necessary.

[0123] <<Non-aqueous electrolyte>>For example, a non-aqueous electrolytic liquid can be used as the non-aqueous electrolyte.The non-aqueous electrolytic liquid described herein is an electrolytic liquid in which an electrolyte salt is dissolved in a non-aqueous solvent.The non-aqueous solvent used in the non-aqueous electrolytic liquid is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, an aprotic organic solvent.There are no particular limitations on the electrolyte salt so long as it has high ionic conductivity and is soluble in the non-aqueous solvent.Examples of a cation constituting the electrolyte salt include, but are not limited to, a lithium ion.FN202401504An anion constituting the alkali metal salt is not particularly limited and can be appropriately selected depending on the purpose. However, the anion preferably includes a halogen atom. Specific examples thereof include, but are not limited to, BFF, PFe", AsFe", CF3SO3’, (CF3SO2)2N’, and (C2F5SO2)2N-.The alkali metal salt is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethylsulfonyl)imide, and lithium bis(pentafluoroethylsulfonyl)imide. These may be used alone or in combination of two or more types.The concentration of the electrolyte salt in the non-aqueous electrolytic liquid is not particularly limited and can be appropriately selected depending on the purpose. However, the concentration is preferably 1 mol / L or more and 4 mol / L or less.

[0124] <<Separator>>The separator 600 is disposed between the negative electrode 400 and the positive electrode 500 as necessary to prevent a short circuit between the negative electrode 400 and the positive electrode 500.The separator is, for example, a porous film with communicating pores that insulates and separates the positive electrode and the negative electrode used in the electrochemical element such as a secondary battery.The separator is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, a paper such as a kraft paper, a vinylon-mixed paper, or a synthetic pulp-mixed paper, cellophane, a polyethylene graft membrane, a polyolefin nonwoven fabric such as a polypropylene melt-blown nonwoven fabric, a polyamide nonwoven fabric, a glass fiber nonwoven fabric, and a micropore membrane.There are no particular limitations on the size of the separator so long as it can be used in the electrochemical element.The separator may have a single-layer structure or a laminated structure.Note that, when a solid electrolyte is used as the nonaqueous electrolyte, the separator 600 can be omitted.

[0125] The uses of the electricity storage device are not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, a laptop computer, a smart device, an electronic book player, a portable fax machine, a portable copier, a portable printer, a headphone stereo, a video movie player, a liquid crystal television, a handy cleaner, a portable CD player, a MiniDisc player, a transceiver, an electronic diary, a calculator, a memory card, a portable tape recorder, a radio, a backup power source, a motor, lighting equipment, a toy, a gaming console, a clock, a strobe, and a camera.FN202401504As described above, the electricity storage device of the present embodiment includes the electrode of the present embodiment. Thus the electricity storage device can exhibit the same effects as the electrode of the present embodiment.[Examples]

[0126] Embodiments of the present invention are specifically described below with Examples and Comparative examples. However, embodiments of the present invention are not limited to these examples. Note that, in the following Examples and Comparative examples, unless otherwise specified, “parts” means “parts by mass” and “%” means “% by mass”.

[0127] (Example 1)Preparation of insulating layer forming liquid composition>A pre-dispersion liquid, in which 45.0 parts by mass of LS-711CB (a-alumina manufactured by Nippon Light Metal Co., Ltd) as the insulating inorganic particles, 1.35 parts by mass of GK570 (manufactured by Daikin Industries, Ltd.) as the insulating layer forming binder, 1.35 parts by mass of AKM0531 (manufactured by NOF Corp.) as the dispersant, and 52.3 parts by mass of ethyl lactate as the dispersion medium were mixed, was placed in a glass ball mill pot together with 5 mmO zirconium beads, and the sealed pot was placed on a mill rotating table to disperse the mixture, thereby obtaining an insulating layer forming liquid composition. Note that the pot rotation speed during dispersion was 35 rpm, and dispersion was judged to be complete when the viscosity change reached a steady state.

[0128] Production of negative electrode>A negative electrode composite layer forming liquid composition was prepared by mixing 97 parts of graphite (manufactured by JFE Chemical Corp., model number BTM-DMP), 1 part by mass of a thickener (carboxymethyl cellulose manufactured by DKS Co. Ltd., model number CELLOGEN HS-6), 2 parts by mass of a polymer (acrylic resin manufactured by Zeon Corp., model number AZ-9129), and 100 parts by mass of water as a solvent.The negative electrode composite layer forming liquid composition was applied onto a copper negative electrode substrate (manufactured by Furukawa Electric Co., Ltd., model number NC-WS, foil thickness of 10 pm) and then dried to obtain a negative electrode with the negative electrode composite layers formed on both sides with a coating amount per unit area (area density) of 9 mg / cm2on each side. The thickness of the negative electrode at this time was 216 pm, and the volume density of the negative electrode was 0.91 g / cm3.Next, the negative electrode was pressed with a roll press machine so that the volume density of the negative electrode became 1.6 g / cm3, thereby obtaining a negative electrode to be used.

[0129] Production of positive electrode>FN202401504A slurry was produced by preparing 93 parts by mass of lithium nickel cobalt manganese oxide (NCM622 manufactured by Beijing Easpring Material Technology Co., Ltd.) as the positive electrode active material, 3 parts by mass of a conductive assistant (Ketjenblack manufactured by Lion Specialty Chemicals Co., Ltd., model number 600JD), and 4 parts by mass of polyvinylidene fluoride (PVDF) (manufactured by Solvay, model number SOLEF 5130) as the electrode composite layer forming binder, and dispersing them in N- methylpyrrolidone (NMP) (manufactured by Mitsubishi Chemical Group Corp.). This slurry was applied onto a positive electrode substrate made of aluminum (manufactured by UACJ Corp., model number 1N30) and then dried to obtain a positive electrode with the positive electrode composite layers formed on both sides with a coating amount per unit area (area density) of 15.0 mg / cm2Next, the positive electrode was compression-molded using a roll press machine so that the volume density of the positive electrode became 3.4 g / cm3, thereby obtaining a positive electrode to be used.

[0130] <Formation of insulating layer>The insulating layer forming liquid composition was printed along a boundary between a positive electrode substrate exposed portion and the positive electrode composite layer, so that the resulting printed product had a width of 10 mm, a covering width of 1 mm, and a film thickness at the positive electrode substrate exposed portion of 5 pm. An inkjet head (MH2420 manufactured Ricoh Co., Ltd.) was used for printing.

[0131] < Production of electrochemical element>The positive electrodes and the negative electrodes thus produced were alternately laminated with film separators (manufactured by Toray Industries, Inc., model No. F20BHE) between them to form an electrode element in which three positive electrodes and four negative electrodes were laminated. Uncoated parts of the negative electrodes were collectively welded to a nickel tab serving as a negative electrode lead wire, and uncoated parts of the positive electrodes were collectively welded to an aluminum tab serving as a positive electrode lead wire. This electrode element was impregnated with a non-aqueous electrolytic liquid containing 1.5 M LiPFe in EC:DMC:EMC=1:1:1 and sealed using an aluminum laminate film to produce a lithium ion secondary battery as an electrochemical element.

[0132] (Examples 2 to 30, Comparative examples 1 to 6)Except for changing compositions of the insulating layer forming liquid compositions as described in Table 1 to Table 6, the insulating layer forming liquid compositions and the lithium ion secondary batteries were produced in the same manner as in Example 1.

[0133] Note that details of the materials used in each Example and Comparative example are as follows.FN202401504

[0134] -Binder-•GK570 (weight average molecular weight Mw: 28,000, number average molecular weightMn: 12,000, manufactured by Daikin Industries, Ltd.)•LF200F (weight average molecular weight Mw: 42,000, number average molecular weightMn: 15,000, manufactured by AGC Inc.)•GF-X-101 (weight average molecular weight Mw: 27,000, number average molecular weight Mn: 12,000, manufactured by Toagosei Co., Ltd.)•GF-400 (weight average molecular weight Mw: 77,000, number average molecular weightMn: 26,000, manufactured by Toagosei Co., Ltd.)•SSA-100 (weight average molecular weight Mw: 38,000, number average molecular weight Mn: 14,000, manufactured by Seiko PMC Corp.)• JMR-10H (weight average molecular weight Mw: 60,000, number average molecular weight Mn: 30,000, manufactured by Japan Vam & Poval Co., Ltd.)•EPL5310 (weight average molecular weight Mw: 60,000, number average molecular weight Mn: 30,000, manufactured by DKS Co. Ltd.)•LF916F (weight average molecular weight Mw: 11,000, number average molecular weight Mn: 5,000, manufactured by AGC Inc.)•SOLEF 5130 (weight average molecular weight Mw: 1,100,000, manufactured by Solvay) •KUREHA #9100 (weight average molecular weight Mw: 280,000, manufactured by Kureha Corp.)•KF850 (weight average molecular weight Mw: 200,000, manufactured by Kureha Corp.)

[0135] -Dispersant-•AKM0531 (manufactured by NOF Corp.)•SC0505K (manufactured by NOF Corp.)•ISOBAM- 10 (manufactured by Kuraray Co., Ltd.)•HKM-50A (manufactured by NOF Corp.)•DISPERBYK-108 (manufactured by BYK-Chemie)•DISPERBYK-2000 (manufactured by BYK-Chemie)•SN-DISPERSANT 9228 (manufactured by San Nopco Ltd.)

[0136] -Insulating inorganic particles-•LS-711CB (manufactured by Nippon Light Metal Co., Ltd.)•CT-3000LSSG (manufactured by Almatis)• SEPal-60 (manufactured by Alteo)• AKP-3000 (manufactured by Sumitomo Chemical Co., Ltd.)•BMB-07 (manufactured by Kawai Lime Industry Co., Ltd.)•F-10 (manufactured by Showa Denko K. K.)FN202401504•TZ-3YS (manufactured by Tosoh Corp.)• AA07 (manufactured by Sumitomo Chemical Co., Ltd.)• AA1.5 (manufactured by Sumitomo Chemical Co., Ltd.)

[0137] The weight average molecular weight Mw and the number average molecular weight Mn of the binder were measured by gel permeation chromatography (GPC). Columns TSK G2000HXL and G4000HXL (manufactured by Tosoh Corp.) were connected to a high-speed GPC device GPC-8020 (manufactured by Tosoh Corp.), the column temperature was set to 40°C, and then tetrahydrofuran containing the stabilizer BHT (manufactured by FUJIFILM Wako Pure Chemical Corp.) was passed through the columns as a solvent at a flow rate of 1.0 mL / min. A measurement sample was prepared by adjusting the resin concentration to 0.5% by mass using the same solvent as that passed through the device. A measurement volume was set to 10 pL. For the analysis, the weight average molecular weight Mw and the number average molecular weight Mn were calculated based on a molecular weight calibration curve created using a monodisperse polystyrene standard sample (manufactured by Tosoh Corp.).

[0138] Evaluation of thixotropy of insulating layer forming liquid composition>The thixotropy of each insulating layer forming liquid composition was evaluated using an E- type viscometer (TVE-25L manufactured by Tokisangyo). The viscosity measured at a rotation speed of 100 rpm using a standard rotor 1°34’ *R24 was taken as a viscosity A, and the viscosity measured at a rotation speed of 10 rpm was taken as a viscosity B. Then, a ratio [B / A] of the viscosity B relative to the viscosity A was calculated and evaluated. Note that the number of samples was two, and the average value was used as the ratio. Note that a score of “fair” or higher was considered acceptable. [Evaluation criteria]Good: the ratio [B / A] is 0.95 or more and 1.05 or less.Fair: the ratio [B / A] is 0.8 or more and less than 0.95, or more than 1.05 and 1.2 or less.Poor: the ratio [B / A] is less than 0.8 or more than 1.2.

[0139] Evaluation of ejection properties of insulating layer forming liquid composition> Each insulating layer forming liquid composition was evaluated for ejection properties using an inkjet head (MH2420 manufactured by Ricoh Co., Ltd.). Note that a score of “fair” or higher was considered acceptable.[Evaluation criteria]Good: the composition could be continuously ejected for 10 minutes from all nozzles.Fair: the composition could be ejected from all nozzles although some nozzles had ejection abnormalities such as deformed ejection and abnormal ejection speed.Poor: the composition could not be ejected from some nozzles.

[0140] FN202401504Evaluation of continuous ejection properties of insulating layer forming liquid composition> Each insulating layer forming liquid composition was continuously ejected for 30 minutes using an inkjet head (MH2420 manufactured by RICOH Co., Ltd.), and the ejection state after 1 minute and 30 minutes was compared.Note that a score of “fair” or higher was considered acceptable.[Evaluation criteria]Good: there was no change in the ejection state after continuous ejection for 30 minutes. Fair: the composition could be ejected from all nozzles after continuous ejection for 30 minutes although some nozzles had ejection abnormalities such as deformed ejection and abnormal ejection speed.Poor: the composition could not be ejected from some nozzles after continuous ejection for 30 minutes.

[0141] Evaluation of redispersibility >Each insulating layer forming liquid composition in an amount of 400 mL was placed in a wide-mouth bottle. After the lid was closed, the bottle was left to stand at room temperature for 30 days. Then, the composition was stirred for 1 hour using a stirring device (SKH-40SA manufactured by Misugi Ltd.) to obtain a redispersion liquid. After diluting the redispersion liquid so that the solid content was 10% by mass or less, the median diameter D50 of the insulating inorganic particles in the insulating layer forming liquid composition was measured using a concentrated-type particle size analyzer (FP AR- 1000 manufactured by Otsuka Electronics Co., Ltd.). A rate of change (in particle size) from the particle size before storage was evaluated. Note that a score of “fair” or higher was considered acceptable.[Evaluation criteria]Good: the rate of change of less than ±5%Fair: the rate of change of ±5% or more and less than ±15%Poor: the rate of change of ±15% or more

[0142] Evaluation of strength (before cycle test)>A peel strength evaluation was performed using the positive electrode on which the insulating layer was formed. As an evaluation device, a light-load type adhesive / film peeling analyzer (VPA-3S manufactured by Kyowa Interface Science Co., Ltd.) was used with an 8 mm wide tape (cellophane tape manufactured by Nittosha Co., Ltd.). The tape was adhered onto the insulating layer, and the peeling operation was performed at a peel angle of 90 degrees and a peel speed of 30 mm / min. The average value of the load applied to the load cell was read during the peeling operation to evaluate the strength.[Evaluation criteria]Good: the peel strength of 50 N / m or more Poor: the peel strength of less than 50 N / mFN202401504

[0143] < Eval nation of strength (after cycle test)>The positive electrode lead wire and the negative electrode lead wire of each lithium ion secondary battery were connected to a charge / discharge tester (manufactured by Hokuto Denko, Corp., model number HJ0610SD8Y), and the battery was charged at a constant current and constant voltage with a maximum voltage of 4.2 V and a current rate of 0.2 C for 5 hours. After charging was completed, the battery was left to stand in a thermostatic chamber at 40°C for 5 days. The battery was then discharged to 2.5 V at a constant current with a current rate of 0.2 C. The battery was then charged at a constant current and constant voltage with a maximum voltage of 4.2 V and a current rate of 0.2 C for 5 hours. After a 10- minute break, the battery was discharged to 2.5V at a constant current with a current rate of 0.2 C. The discharge capacity at this time was defined as the initial capacity. In the following evaluation, a cell with a discharge capacity within a range of 180 mAh+1.8 mAh was used.The initial capacity was taken as the standard for full charge, and a cycle test, in which the battery was fully charged from a discharged state to a voltage of 4.2 V with a current rate of 1 C and then discharged to 2.5 V with a current rate of 2 C, was performed 300 times. The cycle test was performed at a test environment of 45°C using a thermostatic chamber manufactured by Espec Corp.After the cycle test, the sample was disassembled to take out the positive electrode. The positive electrode was lightly washed with dimethyl carbonate (DMC), and then the preservation of the insulating layer at the boundary was examined.[Evaluation criteria]Good: the insulating layer is preserved, 90% or more of the printing width at the time of printing is maintained.Poor: the insulating layer is partially peeled off, less than 90% of the printing width at the time of printing is maintained.

[0144] [Table 1]FN202401504FN202401504

[0145] [Table 2]FN202401504

[0146] [Table 3]FN202401504

[0147] [Table 4]FN202401504

[0148] [Table 5]FN202401504

[0149] [Table 6]

[0150] It is clear from the results of Examples 1 to 5, 8 to 13, 16 to 18, 22 and 23, and 26 that, when all of the preferred aspects of the binder, dispersant, and insulating inorganic particles are satisfied, an insulating layer having excellent ejection properties, continuous ejection properties, and redispersibility, as well as excellent strength, can be obtained.FN202401504It is clear from the results of Examples 6 and 14 that, when the ratio of the binder relative to the insulating inorganic particles is too high, the redispersibility, the ejection properties, the continuous ejection properties, and the thixotropy decrease.It is clear from the results of Example 7 that, when the ratio of the binder (GK570) relative to the insulating inorganic particles is too low, the ejection properties and the film strength after the cycle test decrease.It is clear from the results of Example 15 that, when the ratio of the dispersant (AKM0531) relative to the insulating inorganic particles is too high, the ejection properties, the continuous ejection properties, and the thixotropy decrease.It is clear from the results of Examples 19 to 21 that, when the dispersant does not include the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2), the ejection properties, the continuous ejection properties, and the thixotropy decrease.It is clear from the results of Examples 24 and 25 that, when alumina is not used as the insulating inorganic particles, the redispersibility and the continuous ejection properties decrease.It is clear from the results of Example 27 that, when the particle size of the insulating inorganic particles is large, the viscosity of the liquid composition increases, and the ejection properties and the continuous ejection properties decrease.It is clear from the results of Example 28 that, when the binder type is a styrene acrylic resin, the film strength after the cycle test decreases.It is clear from the results of Example 29 that, when the binder type is a polyvinyl alcohol resin, the thixotropy and the film strength after the cycle test decrease.It is clear from the results of Example 30 that, when the binder type is a polyimide resin, the ejection properties, the continuous ejection properties, the thixotropy, and the film strength after the cycle test decrease.

[0151] It is clear from the results of Comparative examples 1 to 4 that, when the binder includes a fluoroethylene group and a vinyl ether group and has a weight average molecular weight of 25,000 or more and 80,000 or less, an insulating layer having the excellent ejection properties, continuous ejection properties, and redispersibility, as well as the excellent strength can be obtained.It is clear from the results of Comparative examples 5 and 6 that, when the dispersant includes a carboxyl group or an acid anhydride group, an insulating layer having the excellent ejection properties, continuous ejection properties, and redispersibility, as well as the excellent strength can be obtained.

[0152] For example, aspects of the present invention include the following.< Aspect 1>FN202401504An insulating layer forming liquid composition including: insulating inorganic particles; a dispersant including a carboxyl group or an acid anhydride group; and a binder, in which the binder has a weight average molecular weight of 25,000 or more and 80,000 or less.< Aspect 2>The insulating layer forming liquid composition according to the < Aspect 1>, in which the binder includes a fluoroethylene group and a vinyl ether group.< Aspect 3>The insulating layer forming liquid composition according to the <Aspect 1> or <Aspect 2>, in which the dispersant includes at least one selected from a structural unit represented by the following general formula (1), a structural unit represented by the following general formula (2), and a structural unit represented by the following general formula (3): [Chemical 7]... General Formula (1)[General Formula (2)[Chemical 9]General Formula (3) where, in the general formulas (1) to (3), * represents a bonding site to an adjacent main chain structural unit, and M represents an ammonium salt.FN202401504< Aspect 4>The insulating layer forming liquid composition according to any of the < Aspect 1> to <Aspect 3>, in which a ratio [B / A] of a viscosity B relative to a viscosity A is 0.95 or more and 1.05 or less, where the viscosity A is a viscosity measured using an E-type viscometer at 100 rpm, and the viscosity B is a viscosity measured using the E-type viscometer at 10 rpm. < Aspect 5>The insulating layer forming liquid composition according to any of the < Aspect 1> to <Aspect 4>, in which the insulating inorganic particles comprise a-alumina or boehmite. < Aspect 6>The insulating layer forming liquid composition according to any of the < Aspect 1> to < Aspect 5>, in which the insulating inorganic particles have a median diameter of 200 nm or more and less than 1,000 nm.< Aspect 7 >A storage container including: a container; and the insulating layer forming liquid composition according to any of the < Aspect 1> to < Aspect 6> stored in the container.< Aspect 8>An electrode manufacturing apparatus including: a storage container storing the insulating layer forming liquid composition according to any of the < Aspect 1> to < Aspect 6>; and an insulating layer forming liquid composition applying means configured to apply the insulating layer forming liquid composition onto a substrate.< Aspect 9>The electrode manufacturing apparatus according to the < Aspect 8>, in which the insulating layer forming liquid composition applying means is inkjet.<Aspect 10>An electrode including: a substrate; an electrode composite layer disposed on a part of the substrate; and an insulating layer covering a boundary between a substrate exposed portion in which the substrate is exposed and the electrode composite layer, in which the insulating layer includes insulating inorganic particles, a dispersant, and a binder, the dispersant includes at least one selected from a structural unit represented by the following general formula (1), a structural unit represented by the following general formula (2), and a structural unit represented by the following general formula (3), and the binder has the weight average molecular weight of 25,000 or more and 80,000 or less:[Chemical 10]FN202401504... General Formula (1)[Chemical 11]... General Formula (2)[Chemical 12]... General Formula (3) where, in the general formulas (1) to (3), * represents a bonding site to an adjacent main chain structural unit, and M represents an ammonium salt.< Aspect 11 >The electrode according to the <Aspect 10>, in which the binder includes a fluoroethylene group and a vinyl ether group.<Aspect 12>The electrode according to the <Aspect 10> or < Aspect 11 >, in which the insulating layer is disposed at the boundary and an end part on the electrode composite layer.< Aspect 13 >The electrode according to the <Aspect 10> or < Aspect 11 >, in which the insulating layer is disposed at the boundary and on an upper surface of the electrode composite layer.<Aspect 14>The electrode according to any of the <Aspect 10> to < Aspect 13 >, in which a peel strength of the insulating layer from the substrate is 50 N / m or more.< Aspect 15 >FN202401504An electricity storage device including the electrode according to any of the <Aspect 10> to <Aspect 14>.

[0153] The insulating layer forming liquid composition according to any of the < Aspect 1> to< Aspect 6>, the storage container according to the < Aspect 7>, the electrode manufacturing apparatus according to the <Aspect 8> or <Aspect 9>, the electrode according to any of the <Aspect 10> to <Aspect 14>, and the electricity storage device according to the <Aspect 15> can solve the various conventional problems and achieve the object of the present invention.

[0154] The above-described embodiments are illustrative and do not limit the present invention. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements and / or features of different illustrative embodiments may be combined with each other and / or substituted for each other within the scope of the present invention.

[0155] This patent application is based on and claims priority to Japanese Patent Application Nos. 2024-013255 and 2024-135378, filed on January 31, 2024 and August 14, 2024, in the Japan Patent Office, the entire disclosure of each of which is hereby incorporated by reference herein.[Reference Signs List]

[0156] 100 Electrode1 Substrate11 Substrate exposed portion2 Electrode composite layer3 Insulating layer

Claims

FN202401504[CLAIMS]

1. An insulating layer forming liquid composition comprising: insulating inorganic particles; a dispersant including a carboxyl group or an acid anhydride group; and a binder, wherein the binder has a weight average molecular weight of 25,000 or more and 80,000 or less.

2. The insulating layer forming liquid composition according to claim 1, wherein the binder includes a fluoroethylene group and a vinyl ether group.

3. The insulating layer forming liquid composition according to claim 1 or 2, wherein the dispersant includes at least one selected from a structural unit represented by a following general formula (1), a structural unit represented by a following general formula (2), and a structural unit represented by a following general formula (3):[Chemical 1]General Formula (1) . General Formula (2)... General Formula (3)FN202401504 where, in the general formulas (1) to (3), * represents a bonding site to an adjacent main chain structural unit, and M represents an ammonium salt.

4. The insulating layer forming liquid composition according to any one of claims 1 to 3, wherein a ratio [B / A] of a viscosity B relative to a viscosity A is 0.95 or more and 1.05 or less, where the viscosity A is a viscosity measured using an E-type viscometer at 100 rpm, and the viscosity B is a viscosity measured using the E-type viscometer at 10 rpm.

5. The insulating layer forming liquid composition according to any one of claims 1 to 4, wherein the insulating inorganic particles comprise a-alumina or boehmite.

6. The insulating layer forming liquid composition according to any one of claims 1 to 5, wherein the insulating inorganic particles have a median diameter of 200 nm or more and less than 1,000 nm.

7. A storage container comprising: a container; and the insulating layer forming liquid composition according to any one of claims 1 to 6 stored in the container.

8. An electrode manufacturing apparatus comprising: a storage container storing the insulating layer forming liquid composition according to any one of claims 1 to 6; and an insulating layer forming liquid composition applying means configured to apply the insulating layer forming liquid composition onto a substrate.

9. The electrode manufacturing apparatus according to claim 8, wherein the insulating layer forming liquid composition applying means is inkjet.

10. An electrode comprising: a substrate; an electrode composite layer disposed on a part of the substrate; and an insulating layer covering a boundary between a substrate exposed portion in which the substrate is exposed and the electrode composite layer, wherein the insulating layer includes insulating inorganic particles, a dispersant, and a binder, the dispersant includes at least one selected from a structural unit represented by a following general formula (1), a structural unit represented by a following general formula (2), and a structural unit represented by a following general formula (3), and the binder has a weight average molecular weight of 25,000 or more and 80,000 or less:FN202401504... General Formula (1)[Chemical 5]... General Formula (2) [Chemical 6]... General Formula (3) where, in the general formulas (1) to (3), * represents a bonding site to an adjacent main chain structural unit, and M represents an ammonium salt.

11. The electrode according to claim 10, wherein the binder includes a fluoroethylene group and a vinyl ether group.

12. The electrode according to claim 10 or 11, wherein the insulating layer is disposed at the boundary and an end part on the electrode composite layer.

13. The electrode according to claim 10 or 11, wherein the insulating layer is disposed at the boundary and on an upper surface of the electrode composite layer.

14. The electrode according to any one of claims 10 to 13, wherein a peel strength of the insulating layer from the substrate is 50 N / m or more.

15. An electricity storage device comprising the electrode according to any one of claims 10 to14.

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