Method for manufacturing quasi-solid-state battery

Abstract

This method for manufacturing a quasi-solid-state battery comprises: a step for mixing and consolidating an electrode material that contains an electrolytic solution, an electrode active material, and an electroconductive assistant; a step for supplying the consolidated electrode material to a gap between a blade and a support that is being transported; and a step for leveling the supplied electrode material using the blade to form an electrode layer, the consolidated electrode material having a saturation of 80% or greater.

Description

Quasi-solid battery manufacturing method

[0001] The present disclosure relates to a method for manufacturing a quasi-solid-state battery.

[0002] In recent years, from the viewpoint of safety, quasi-solid-state batteries in which a part of the electrolytic solution is replaced with a solid electrolyte have been studied. The production of a battery electrode using a powder containing an electrode active material generally includes a step of coating a support with an electrode material containing the powder electrode active material.

[0003] For example, JP 2017-533548 A describes a method for manufacturing an electrochemical cell, the method including the steps of coating a semi-solid cathode on a first surface of a positive current collector, coating a semi-solid anode on a first surface of a negative current collector, disposing a separator between the semi-solid cathode and the semi-solid anode, disposing the positive current collector, the negative current collector, and the separator in a pouch, and sealing the pouch to form the electrochemical cell. JP 2021-530829 A describes a method including continuously dispensing a semi-solid electrode slurry onto a current collector, separating the semi-solid electrode slurry into separate portions, and cutting the current collector to form completed electrodes.

[0004] When the solid content of the electrode material is high or when the solid content of the electrode material absorbs a large amount of liquid, the surface of the electrode material dries and becomes powdery, making it difficult to apply the electrode material to a support.

[0005] Therefore, an object of one embodiment of the present disclosure has been achieved in view of the above circumstances, and is to provide a method for manufacturing a quasi-solid battery that has excellent adhesion of an electrode material.

[0006] The present disclosure includes the following aspects. <1> A method for manufacturing a quasi-solid battery, comprising: mixing and consolidating an electrode material containing an electrolyte solution, an electrode active material, and a conductive additive; supplying the consolidated electrode material into a gap between a transported support and a blade; and leveling the supplied electrode material with the blade to form an electrode layer on the support, wherein the consolidated electrode material has a degree of saturation of 80% or more. <2> A method for manufacturing a quasi-solid battery according to <1>, further comprising: atomizing the consolidated electrode material to obtain a plurality of atomized electrode materials, and supplying the plurality of atomized electrode materials into the gap between the support and the blade. <3> A method for manufacturing a quasi-solid battery according to <1> or <2>, wherein an angle formed between a transport direction of the support and a surface of the blade facing the support is 1° to 15°. <4> A method for manufacturing a quasi-solid battery according to any one of <1> to <3>, wherein a shortest distance between a tip of the blade on an upstream side in the transport direction of the support and the support is 1 mm to 20 mm. <5> A method for producing a quasi-solid battery according to any one of <1> to <4>, wherein the electrode layer is a negative electrode layer containing graphite as an electrode active material. <6> A method for producing a quasi-solid battery according to any one of <1> to <5>, wherein the support is a copper foil having a surface roughness Ra of 0.2 μm or less. <7> A method for producing a quasi-solid battery according to any one of <1> to <6>, wherein the support is a separator. <8> A method for producing a quasi-solid battery according to any one of <1> to <7>, wherein a bi-cell battery is produced by forming a negative electrode layer on a separator as a support, and placing the separator side of the separator on which the negative electrode layer has been formed on a positive electrode layer formed on a current collector foil. <9> A method for producing a quasi-solid battery according to <8>, wherein a bi-cell battery is produced by forming negative electrode layers on both sides of a copper foil. <10> The method for producing a quasi-solid-state battery according to any one of <1> to <9>, wherein a negative electrode layer is formed on a separator as a support, and the separator on which the negative electrode layer is formed is placed on a positive electrode layer formed on a current collecting foil, thereby producing a bipolar battery.

[0007] According to one embodiment of the present disclosure, a method for manufacturing a quasi-solid-state battery with excellent adhesion of electrode materials is provided.

[0008] FIG. 1 is a schematic diagram showing an example of a method for forming an electrode layer on a support.

[0009] Hereinafter, an embodiment of a method for manufacturing a quasi-solid-state battery will be described. However, the present disclosure is not limited to the following embodiment and can be implemented with appropriate modifications within the scope of the object of the present disclosure.

[0010] In the present disclosure, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples. The elements in the drawings shown in the present disclosure are not necessarily to scale, and emphasis is placed on clearly illustrating the principles of the present disclosure. Furthermore, in the drawings, components having the same function are denoted by the same reference numerals, and redundant explanations are omitted. In the present disclosure, a combination of two or more preferred forms or embodiments is a more preferred form or embodiment.

[0011] The method for manufacturing a quasi-solid-state battery according to the present disclosure includes the steps of mixing and compacting an electrode material containing an electrolyte, an electrode active material, and a conductive additive (hereinafter also referred to as the "compacting step"); supplying the compacted electrode layer material into a gap between a support being transported and a blade (hereinafter also referred to as the "electrode material supplying step"); and smoothing the supplied electrode material with a blade to form an electrode layer on the support (hereinafter also referred to as the "electrode layer forming step"). The compacted electrode material has a degree of saturation of 80% or more.

[0012] In the past, when the solid content of an electrode material was high or when the solid content of the electrode material absorbed a large amount of liquid, the surface of the electrode material became like a dry powder, making it difficult to apply the electrode material to a support. In contrast, the method for manufacturing a quasi-solid battery according to the present disclosure includes a compaction step, an electrode material supply step, and an electrode layer formation step. The compacted electrode material has a degree of saturation of 80% or more, so that the electrolyte solution easily seeps out of the electrode material. The exuded electrolyte solution provides excellent adhesion of the electrode material to the support.

[0013] JP-T No. 2017-533548 and JP-T No. 2021-530829 do not describe the combination of the compaction step, the electrode material supply step, and the electrode layer formation step.

[0014] <Consolidation Step> The method for producing a quasi-solid battery according to the present disclosure includes a step of mixing an electrolyte solution, an electrode active material, and an electrode material containing a conductive additive, followed by consolidation.

[0015] (Electrode Material) The electrode material contains at least an electrolyte solution, an electrode active material, and a conductive additive, and may contain other components as necessary.

[0016] -Electrolyte Solution- The electrode material contains an electrolyte solution. There are no particular limitations on the electrolyte solution, and any known electrolyte solution can be used. Examples of the electrolyte solution include an electrolyte solution containing an electrolyte and a solvent. Specific examples of the electrolyte solution include an electrolyte solution containing a lithium salt compound as the electrolyte and a carbonate compound as the solvent.

[0017] An example of the lithium salt compound is lithium hexafluorophosphate. The electrolyte solution may contain one kind of lithium salt compound alone, or may contain two or more kinds of lithium salt compounds.

[0018] Examples of carbonate compounds include linear carbonate compounds such as ethyl methyl carbonate (also referred to as EMC), dimethyl carbonate (also referred to as DMC), and diethyl carbonate (DEC), and cyclic carbonate compounds such as ethylene carbonate (also referred to as EC) and propylene carbonate (also referred to as PC). The electrolyte may contain one type of carbonate compound alone, or may contain two or more types of carbonate compounds, or may use one or more linear carbonate compounds and one or more cyclic carbonate compounds in combination.

[0019] As the electrolyte contained in the electrolytic solution, for example, a known inorganic solid electrolyte can be used.

[0020] An ionic liquid may be used as a component of the electrolytic solution, for example. The ionic liquid may be used as either an electrolyte or a solvent.

[0021] The content of the electrolyte solution relative to the total volume of the electrode material is preferably 70% by volume or less, and may be 50% by volume or less, or 40% by volume or less. The lower limit of the content of the electrolyte solution relative to the total volume of the electrode material is not limited, and may be 20% by volume or more, or 30% by volume or more. The content of the electrolyte solution relative to the total volume of the electrode material is, for example, 30% by volume to 50% by volume.

[0022] - Electrode active material - An electrode active material is a material capable of inserting and releasing ions of a metal element belonging to Group 1 or Group 2 of the periodic table. The electrode active material is contained in a solid component. Examples of the electrode active material include a positive electrode active material and a negative electrode active material.

[0023] The positive electrode active material is not limited and may be any known electrode active material used for positive electrodes. The positive electrode active material is preferably a positive electrode active material that can reversibly insert and release lithium ions.

[0024] Specific examples of the positive electrode active material include transition metal oxides and elements that can be composited with lithium (e.g., sulfur). Among the above, the positive electrode active material is preferably a transition metal oxide.

[0025] The transition metal oxide is preferably a transition metal oxide containing at least one transition metal element (hereinafter referred to as "element Ma") selected from the group consisting of Co (cobalt), Ni (nickel), Fe (iron), Mn (manganese), Cu (copper), and V (vanadium).

[0026] When the transition metal oxide contains Li and the element Ma, the molar ratio of Li to Ma (Li / Ma) is preferably 0.3 to 2.2.

[0027] The transition metal oxide may also contain at least one transition metal element (hereinafter referred to as "element Mb") selected from the group consisting of Group 1 elements other than lithium, Group 2 elements, Al (aluminum), Ga (gallium), In (indium), Ge (germanium), Sn (tin), Pb (lead), Sb (antimony), Bi (bismuth), Si (silicon), P (phosphorus), and B (boron). The content of element Mb is preferably 0 mol % to 30 mol % relative to the amount of element Ma.

[0028] Examples of transition metal oxides include transition metal oxides having a layered rock salt structure, transition metal oxides having a spinel structure, lithium-containing transition metal phosphate compounds, lithium-containing transition metal halide phosphate compounds, and lithium-containing transition metal silicate compounds.

[0029] Examples of transition metal oxides having a layered rock salt structure include LiCoO ２ (Lithium cobalt oxide [LCO]), LiNi ２ O ２ (lithium nickel oxide), LiNi ０．８５ Co ０．１０ Al ０．０５ O ２ (nickel cobalt lithium aluminum oxide [NCA]), LiNi １／３ Co １／３ Mn １／３ O ２ (lithium nickel manganese cobalt oxide [NMC]), and LiNi ０．５ Mn ０．５ O ２ (lithium manganese nickel oxide).

[0030] Examples of transition metal oxides having a spinel structure include LiCoMnO ４ , Li ２ FeMn ３ O ８ , Li ２ CuMn ３ O ８ , Li ２ CrMn ３ O ８ , and Li ２ NiMn ３ O ８ Examples include:

[0031] Examples of lithium-containing transition metal phosphate compounds include olivine-type iron phosphate salts (e.g., LiFePO ４ , and Li ３ Fe ２ (P.O. ４ ) ３ ), iron pyrophosphate (e.g., LiFeP ２ O ７ ), cobalt phosphate salts (e.g., LiCoPO ４ ), monoclinic Nasicon-type vanadium phosphate salts (e.g., Li ３ V ２ (P.O. ４ ) ３ (Lithium vanadium phosphate)).

[0032] Examples of lithium-containing transition metal halophosphate compounds include iron fluorophosphates (e.g., Li ２ FePO ４ F), manganese fluorophosphate salts (e.g., Li ２ MnPO ４ F), and cobalt fluorophosphate salts (e.g., Li ２ CoPO ４ F).

[0033] Examples of lithium-containing transition metal silicate compounds include Li ２ FeSiO ４ , Li ２ MnSiO ４ , and Li ２ CoSiO ４ Examples include:

[0034] The transition metal oxide is preferably a transition metal oxide having a layered rock salt structure, such as LiCoO ２ (Lithium cobalt oxide [LCO]), LiNi ０．８５ Co ０．１０ Al ０．０５ O ２ (nickel cobalt lithium aluminum oxide [NCA]), and LiNi １／３ Co １／３ Mn １／３ O ２ (nickel manganese cobalt oxide [NMC]) and more preferably at least one compound selected from the group consisting of:

[0035] The positive electrode active material may be a commercially available product or a synthetic product produced by a known method (e.g., a calcination method). For example, the positive electrode active material obtained by the calcination method may be washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent. The positive electrode active material may also have a carbon coating on its surface.

[0036] The shape of the positive electrode active material is not limited, but from the viewpoint of ease of handling, it is preferably in the form of particles.

[0037] The volume average particle size of the positive electrode active material is not limited and can be, for example, 0.1 μm to 50 μm. The volume average particle size of the positive electrode active material is preferably 0.3 μm to 40 μm, and more preferably 0.5 μm to 30 μm. When the volume average particle size of the positive electrode active material is 0.3 μm or more, scattering of the positive electrode active material during handling can be suppressed. When the volume average particle size of the positive electrode active material is 40 μm or less, the thickness of the electrode layer can be easily adjusted and the occurrence of voids during the molding process can be suppressed.

[0038] The volume average particle size of the positive electrode active material is measured by the following method. A dispersion containing 0.1 mass % or less of the positive electrode active material is prepared by mixing the positive electrode active material with a solvent (e.g., pure water, ethanol, heptane, octane, toluene, or xylene). The dispersion is irradiated with 1 kHz ultrasound for 10 minutes and used as a measurement sample. Using a laser diffraction / scattering particle size distribution measurement device (e.g., LA-960 manufactured by Horiba, Ltd.), data is acquired 50 times at a temperature of 25°C, and the volume average particle size is determined from the volume frequency particle size distribution. A quartz cell is used as the measurement cell. The above measurement is performed using five samples, and the average of the measured values ​​is used as the volume average particle size of the positive electrode active material. For other detailed conditions, refer to "JIS Z 8828:2013" as necessary.

[0039] Examples of methods for adjusting the particle size of the positive electrode active material include methods using a pulverizer, a crusher, or a classifier. Alternatively, a known milling method may be used to adjust the particle size of the positive electrode active material.

[0040] The positive electrode active material may be used alone or in combination of two or more. Even when one type of positive electrode active material is used, positive electrode active materials having different particle sizes may be used in combination.

[0041] The content of the positive electrode active material relative to the total volume of the electrode material is preferably 30 to 60% by volume, more preferably 35 to 55% by volume, and even more preferably 40 to 50% by volume.

[0042] The negative electrode active material is not limited, and any known negative electrode active material used for negative electrodes can be used. The negative electrode active material is preferably a negative electrode active material that can reversibly insert and release lithium ions.

[0043] Examples of the negative electrode active material include carbonaceous materials, metal oxides (e.g., tin oxide), silicon oxide, metal composite oxides, lithium alone, lithium alloys (e.g., lithium-aluminum alloys), and metals capable of forming alloys with lithium (e.g., Sn, Si, and In). Among these, the negative electrode active material is preferably a carbonaceous material or a lithium composite oxide from the viewpoint of reliability.

[0044] Carbonaceous materials are materials consisting essentially of carbon. Examples of carbonaceous materials include petroleum pitch, carbon black (e.g., acetylene black), graphite (e.g., natural graphite and artificial graphite (e.g., vapor-grown graphite)), hard carbon, and carbonaceous materials obtained by calcining synthetic resins (e.g., polyacrylonitrile (PAN) and furfuryl alcohol resin). Examples of carbonaceous materials include carbon fibers (e.g., polyacrylonitrile-based carbon fibers, cellulose-based carbon fibers, pitch-based carbon fibers, vapor-grown carbon fibers, dehydrated PVA (polyvinyl alcohol)-based carbon fibers, lignin carbon fibers, glassy carbon fibers, and activated carbon fibers). Examples of graphite include mesophase microspheres, graphite whiskers, and tabular graphite. In this disclosure, "tabular" refers to a shape having two major planes facing in opposite directions.

[0045] Among these, from the viewpoint of practicality, it is preferable that the negative electrode active material contains graphite.

[0046] The metal composite oxide is preferably a metal composite oxide capable of absorbing and desorbing lithium. From the viewpoint of high current density charge / discharge characteristics, the metal composite oxide capable of absorbing and desorbing lithium preferably contains at least one element selected from the group consisting of titanium and lithium.

[0047] The metal oxide and metal composite oxide are particularly preferably amorphous oxides.

[0048] The metal oxides and metal composite oxides are also preferably chalcogenides, which are reaction products of metal elements and elements of Group 16 of the periodic table.

[0049] Among the compound group consisting of amorphous oxides and chalcogenides, amorphous oxides and chalcogenides of metalloid elements are preferred, and oxides and chalcogenides containing at least one element selected from the group consisting of elements of Groups 13 to 15 in the periodic table, Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi are more preferred.

[0050] It is also preferable that the negative electrode active material further contains titanium. From the viewpoint that the volume change during the absorption and desorption of lithium ions is small, and thus rapid charge and discharge characteristics are excellent, and that deterioration of the electrode is suppressed, thereby enabling an improvement in the life of the lithium ion secondary battery, the negative electrode active material containing titanium is preferably Li ４ Ti ５ O １２ (lithium titanate [LTO]) is preferred.

[0051] The negative electrode active material may be a commercially available product or a synthetic product produced by a known method (e.g., a calcination method). For example, the negative electrode active material obtained by the calcination method may be washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

[0052] The negative electrode active material is available, for example, as CGB20 (Nippon Graphite Industries Co., Ltd.).

[0053] The composition of the negative electrode active material is measured using inductively coupled plasma (ICP) emission spectroscopy.

[0054] The shape of the negative electrode active material is not limited, but is preferably particulate from the viewpoints of ease of handling and ease of control of uniformity during mass production.

[0055] The volume average particle size of the negative electrode active material is preferably 0.1 μm to 60 μm, more preferably 0.3 μm to 50 μm, and particularly preferably 0.5 μm to 40 μm. The volume average particle size of the negative electrode active material is measured by a method similar to the method for measuring the volume average particle size of the positive electrode active material.

[0056] The particle size of the negative electrode active material can be adjusted, for example, by using a pulverizer or a classifier.

[0057] The negative electrode active material may be used alone or in combination of two or more. Even when one type of negative electrode active material is used, negative electrode active materials having different particle sizes may be used in combination.

[0058] The content of the negative electrode active material relative to the total volume of the electrode material is preferably 30 to 60% by volume, more preferably 35 to 57% by volume, and even more preferably 45 to 55% by volume.

[0059] The surfaces of the positive electrode active material and the negative electrode active material may each be coated with a surface coating agent. Examples of the surface coating agent include metal oxides containing Ti, Nb, Ta, W, Zr, Si, or Li. Examples of the metal oxide include titanate spinel, tantalum-based oxides, niobium-based oxides, and lithium niobate-based compounds.

[0060] Conductive additives: The electrode material contains a conductive additive from the viewpoint of improving the electronic conductivity of the electrode active material. There are no limitations on the conductive additive, and known conductive additives can be used. The conductive additive is contained in the solid component.

[0061] Examples of conductive additives include graphite (e.g., natural graphite and artificial graphite), carbon black (e.g., acetylene black, ketjen black, and furnace black), amorphous carbon (e.g., needle coke), carbon fibers (e.g., vapor-grown carbon fibers and carbon nanotubes), other carbonaceous materials (e.g., graphene and fullerene), metal powders (e.g., copper powder and nickel powder), metal fibers (e.g., copper fibers and nickel fibers), and conductive polymers (e.g., polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives).

[0062] The conductive additive may be used alone or in combination of two or more. The content of the conductive additive relative to the total volume of the electrode material is preferably 0.05% by volume to 5% by volume, more preferably 0.1% by volume to 4% by volume, and even more preferably 0.5% by volume to 3% by volume. In the method for producing a quasi-solid battery according to the present disclosure, the amount of the conductive additive used is preferably determined so that the content in the electrode layer falls within the above-mentioned range.

[0063] The electrode material may contain, as a liquid component, a solvent (hereinafter simply referred to as "solvent") other than the solvent contained as a component of the electrolyte. Examples of the solvent include alcohol compound solvents, ether compound solvents, amide compound solvents, amino compound solvents, ketone compound solvents, aromatic compound solvents, aliphatic compound solvents, and nitrile compound solvents.

[0064] The boiling point of the solvent at normal pressure (i.e., 1 atmosphere) is preferably 50° C. or higher, and more preferably 70° C. or higher. The upper limit of the boiling point of the solvent at normal pressure (i.e., 1 atmosphere) is preferably 250° C. or lower, and more preferably 220° C. or lower.

[0065] The solvent may be used alone or in combination of two or more. The content of the liquid components (i.e., the electrolyte solution and the solvent) relative to the total volume of the electrode material is preferably 70% by volume or less, and may be 50% by volume or less, or may be 40% by volume or less. The lower limit of the content of the liquid components relative to the total volume of the electrode material is not limited, and may be 20% by volume or more, or may be 30% by volume or more. The content of the liquid components relative to the total volume of the electrode material is preferably 30% by volume to 50% by volume.

[0066] Note that the liquid components contained in the electrode material, i.e., the components in the electrode layer that are liquid at 25° C., are preferably liquid even at −10° C., and are preferably liquid even at −20° C. In other words, the components in the electrode layer that are liquid at 25° C. are preferably components that do not solidify even at −10° C., and are preferably components that do not solidify even at −20° C.

[0067] Other Components: In addition to the above components, the electrode material may contain inorganic solid electrolytes, binders, dispersants, other additives, and the like. From the viewpoint of improving energy density, the electrode material preferably has a low binder (also referred to as a resin component) content, preferably 1% by mass or less, and particularly preferably no binder (0% by mass). In addition to the resin component, the binder includes components called rheology modifiers and dispersants, and examples of such binders include fluorine-containing resins, hydrocarbon-based thermoplastic resins, acrylic resins, and urethane resins. Examples of dispersants include known dispersants capable of dispersing substances to be dispersed. As other additives, known additives added to electrodes can be used.

[0068] -Solid content concentration- The electrode material preferably has a solid content concentration of 40% to 70% by volume. The solid content concentration means the content rate of solid components relative to the total volume of the electrode material. From the viewpoint of battery performance, the solid content concentration is more preferably 46% to 63% by volume. The solid content concentration is calculated from the composition ratio of each component contained in the electrode material and the specific gravity of those components.

[0069] (Method of Mixing Electrode Materials) The method of mixing the electrode materials is not particularly limited, and examples thereof include methods using a ball mill, a bead mill, a planetary mixer, a blade mixer, a roll mill, a kneader, or a disk mill.

[0070] (Method for consolidating electrode material) The method for consolidating the electrode material is not particularly limited as long as it can reduce the porosity of the electrode material. For example, consolidation can be performed using a commonly known molding machine. Consolidation refers to filling voids between powder particles of the electrode material to create a dense state.

[0071] By compacting the electrode material, the electrolyte seeps out onto the surface of the electrode material and becomes more likely to adhere to the support, which will be described later.

[0072] - Degree of saturation - The compacted electrode material has a degree of saturation of 80% or more, and preferably 90% or more. The upper limit of the degree of saturation is, for example, 100%. In the present disclosure, the degree of saturation means the proportion of the electrolyte occupying the gaps between solids. The degree of saturation can be measured by the Vernier caliper method commonly used in soil mechanics, as shown below. The degree of saturation Sr (%) is expressed by the following formula: Sr = (ω × ρ ｓ ) ÷ (e × ρ ｗ ) ω: Water content ratio (%) ρ ｓ : density of the solid content in the electrode material (g / cm ３ ) e: Gap ratio ρ ｗ : Density of the electrolyte (g / cm ３ )

[0073] The water content is expressed by the following formula: ω = (m ｗ / m ｓ ) x 100 m ｗ : Mass of electrolyte in electrode material (g) m ｓ : Mass (g) of solid content in electrode material

[0074] The void ratio is calculated as follows: m (g) of electrode material is packed into a cylinder with a fixed inner diameter. Using a cylinder paired with the cylinder, the packed electrode material is packed into a volume V (cm ３ The wet density of the electrode material is expressed by the following formula: ρ ｔ The dry density of the electrode material is expressed by the following formula: ｄ = ρ ｔ ÷{1+(ω / 100)} e=(ρ ｓ / ρ ｄ )-1

[0075] <Electrode Material Supplying Step> The method for manufacturing a quasi-solid battery according to the present disclosure includes a step of supplying a compacted electrode material into the gap between the support and the blade being transported.

[0076] - Support - The support can be appropriately selected depending on the type of quasi-solid battery to be produced. The support may be a metal foil.

[0077] The thickness of the metal foil is preferably 15 μm or less, more preferably 12 μm or less. The lower limit of the thickness of the metal foil is not particularly limited, and is, for example, 8 μm.

[0078] The thickness of the metal foil is measured by the following method: A portion of the metal foil is cut out and measured using a micrometer (product name "High Precision Digimatic Micrometer MDH-25MC", manufactured by Mitutoyo Corporation).

[0079] The width and length of the metal foil may be appropriately determined from the viewpoint of application to the roll-to-roll method and the width and length of the intended electrode sheet.

[0080] Examples of metals that can be used to form the metal foil include copper, aluminum, silver, gold, and alloys thereof. The metal foil can also be stainless steel, nickel, titanium, or an invar alloy.

[0081] Among these, in terms of shape stability as a metal foil, usage track record, etc., aluminum foil is preferred for the positive electrode, and copper foil is preferred for the negative electrode.

[0082] From the viewpoint of the cost of surface treatment, the surface roughness Ra of the metal foil is preferably 1.0 μm or less, and more preferably 0.2 μm or less. The lower limit of the surface roughness Ra is, for example, 0.1 μm.

[0083] The surface roughness Ra means the arithmetic average roughness, and is measured using an atomic force microscope (AFM).

[0084] From the above viewpoint, the support is preferably a copper foil having a surface roughness Ra of 0.2 μm or less.

[0085] The support may be a separator. A conventional separator used in semi-solid or all-solid batteries can be appropriately selected. Examples of the separator include porous films containing resin materials such as polyethylene, polypropylene, polybutene, polyvinyl chloride, polyethylene terephthalate, polyethersulfone, polyamide, polyimide, polyimideamide, polyaramid, polycycloolefin, nylon, and polytetrafluoroethylene.

[0086] The thickness of the separator is, for example, 0.5 μm to 40 μm.

[0087] The support is placed on, for example, a moving stage provided in the manufacturing apparatus. The support is transported in the transport direction (for example, the direction indicated by the arrow in FIG. 1) by moving the moving stage. The transport speed of the support is not particularly limited and is, for example, 1 m / min to 20 m / min.

[0088] The blade is a flat, plate-like member. The shape, size, material, etc. of the contact portion that comes into contact with the electrode material may be appropriately selected depending on the type of electrode material (type of electrode active material, solids concentration, composition of the electrolyte (viscosity, surface tension), etc.), the size and thickness of the intended electrode layer, etc.

[0089] The contact portion of the blade with the electrode material preferably does not easily adhere to the electrode material. For example, it is preferable that at least the contact portion of the blade exhibits releasability. The blade may be, for example, a resin blade (e.g., a fluororesin such as polytetrafluoroethylene (PTFE) or polyether ether ketone (PEEK)), a metal blade (e.g., stainless steel, aluminum, iron, or cemented carbide), or a ceramic blade. Furthermore, in order to impart releasability to the surface of the contact portion of the blade, the blade may have a surface layer that exhibits releasability (e.g., a surface layer containing a fluororesin, or a surface layer containing silicon-based particles and a resin). Furthermore, in order to enhance the wear resistance of the blade, the metal or ceramic blade body may have a high-hardness coating such as titanium oxide, titanium nitride (TiN), or tungsten carbide.

[0090] The method for supplying the electrode material to the gap between the support and the blade is not particularly limited. For example, the electrode material is continuously or intermittently supplied from a tank storing the electrode material to the upstream side of the support in the transport direction.

[0091] 1 , a distance T2 between a downstream tip 32 of the blade 30 in the conveying direction of the support 20 and the support 20 is preferably shorter than a distance T1 between an upstream tip 31 of the blade 30 in the conveying direction of the support 20 and the support 20. In other words, the blade 30 is preferably provided at an angle with respect to the support 20.

[0092] The distance here means the shortest distance between the downstream tip 32 or the upstream tip 31 and the upper surface of the support 20 .

[0093] The angle formed between the transport direction of the support and the surface of the blade facing the support (angle θ in FIG. 1) is preferably 1° to 15°, and more preferably 5° to 10°.

[0094] When the angle θ is 1° or more, the force required to press the electrode material against the support can be reduced. When the angle θ is 15° or less, the electrolyte solution is likely to seep out of the electrode material, and the electrode material is likely to adhere to the support.

[0095] The distance T1 is preferably 1 mm to 20 mm.

[0096] If the distance T1 is 1 mm to 20 mm, the contact area between the blade and the electrode material does not become too large, and the force required to press the electrode material against the support can be reduced.

[0097] The distance T2 is preferably 0.1 mm to 1 mm, and more preferably 0.2 mm to 0.4 mm.

[0098] The length of the blade in the transport direction of the support 20 is adjusted as appropriate by the angle θ, the distance T1, and the distance T2. The length of the blade is, for example, 8 mm to 115 mm. Note that the blade length here refers to the distance between the downstream tip 32 of the blade 30 in the transport direction of the support 20 and the upstream tip 31 of the blade 30 in the transport direction of the support 20.

[0099] <Electrode Layer Forming Step> The method for manufacturing a quasi-solid battery according to the present disclosure includes a step of smoothing a supplied electrode material with a blade to form an electrode layer on a support.

[0100] As shown in FIG. 1, the support 20 moves in the direction of the arrow, and the electrode material 10 supplied onto the support 20 passes through the blade 30 and is formed into a layer, thereby forming an electrode layer 40 .

[0101] In order to increase the output of a battery, it is desirable to increase the specific surface area, so a thinner electrode layer is desirable. On the other hand, in order to increase the capacity of a battery, it is desirable to increase the amount of electrode material per volume, so a thicker electrode layer is desirable. In order to achieve both the output and capacity of the battery, the thickness of the electrode layer is preferably 30 μm to 400 μm, and more preferably 100 μm to 300 μm.

[0102] The thickness of the electrode layer is measured by the following method: using a non-contact laser displacement meter (Keyence Corporation, multicolor laser coaxial displacement meter, CL-3000), the surface height of the support before coating and the surface height of the electrode layer after coating are measured, and the thickness is determined by subtracting the surface height of the support from the surface height of the electrode layer.

[0103] When the electrode material contains a negative electrode active material as the electrode active material, a negative electrode layer is formed as the electrode layer, and when the electrode material contains a positive electrode active material as the electrode active material, a positive electrode layer is formed as the electrode layer.

[0104] The method for manufacturing a quasi-solid-state battery according to the present disclosure can form both an anode layer and a cathode layer. Conventionally, anode materials with high solid content have low adhesion to a support, making it difficult to form an anode layer. The method for manufacturing a quasi-solid-state battery according to the present disclosure is particularly effective for forming an anode layer.

[0105] Therefore, the electrode layer to be formed is preferably a negative electrode layer containing graphite as an electrode active material.

[0106] <Electrode Material Segmentation Step> The method for producing a quasi-solid battery according to the present disclosure preferably further includes a step of segmenting the compacted electrode material to obtain a plurality of segmented electrode materials (hereinafter also referred to as the “electrode material segmentation step”).

[0107] When the electrode material cutting step is included, the electrode material supply step includes supplying a plurality of cut electrode materials into the gap between the support and the blade. By cutting the electrode material into small pieces beforehand and then supplying it into the gap between the support and the blade, the force required to press the electrode material against the support can be reduced.

[0108] The shape of the divided electrode material is not particularly limited, and examples thereof include a spherical shape and a cylindrical shape.

[0109] When the divided electrode material is spherical or cylindrical, the cross-sectional diameter is preferably 0.5 mm to 10 mm, and more preferably 1 mm to 6 mm. The cross-sectional diameter is measured by the following method: The electrode material is placed on a support, and the height is measured with a vernier caliper.

[0110] The method for comminuted compacted electrode material is not particularly limited, and the electrode material may be comminuted continuously after being compacted in an apparatus used for compacting the electrode material.

[0111] Alternatively, the electrode material may be compacted in an apparatus used for compacting electrode materials, and then the compacted electrode material may be comminuted in a separate apparatus.

[0112] In the method for manufacturing a quasi-solid-state battery according to the present disclosure, a bi-cell battery may be fabricated by forming a negative electrode layer on a separator as a support, and placing the separator side on which the negative electrode layer has been formed on a positive electrode layer formed on a current collector foil. Alternatively, a bi-cell battery may be fabricated by forming negative electrode layers on both sides of a copper foil.

[0113] Examples of the structure of a bi-cell battery include the following: aluminum foil / positive electrode / separator / negative electrode / copper foil / negative electrode / separator / positive electrode / aluminum foil copper foil / negative electrode / separator / positive electrode / aluminum foil / positive electrode / separator / negative electrode / copper foil

[0114] Furthermore, the method for manufacturing a quasi-solid-state battery according to the present disclosure may also include forming a negative electrode layer on a separator as a support, and disposing the separator side on which the negative electrode layer has been formed on a positive electrode layer formed on a current collecting foil, thereby fabricating a bipolar battery.

[0115] Examples of the structure of a bipolar battery include the following: Metal foil / positive electrode / separator / negative electrode / metal foil / positive electrode / separator / negative electrode / metal foil Metal foil / negative electrode / separator / positive electrode / metal foil / negative electrode / separator / positive electrode / metal foil

[0116] The present invention will be explained in more detail below with reference to examples. The materials, amounts used, ratios, details of each step, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. Note that "parts" are all based on mass.

[0117] <Preparation of Positive Electrode Material> LiPF 5 was added to a mixed solution of ethylene carbonate, propylene carbonate, and diethyl carbonate. ６ (electrolyte) was mixed, and then vinylene carbonate was further mixed. 44.8 g of the resulting mixture was taken out and used as the electrolyte. 0.8 g of conductive additive (Ketjen Black) and 154.4 g of positive electrode active material (lithium iron phosphate) were stirred at 1500 rpm for 30 seconds in a mixer (Awatori Rentaro ARE-310, manufactured by Thinky Corporation) to obtain a mixture (155.2 g). 44.8 g of the electrolyte was added to the mixture (155.2 g), and the mixture was stirred at 1500 rpm for 120 seconds in a mixer (Awatori Rentaro ARE-310, manufactured by Thinky Corporation) to obtain a positive electrode material. The volume ratio of the solid component to the liquid component of the resulting positive electrode material was 56:44.

[0118] <Preparation of Negative Electrode Material> An electrolyte solution similar to the electrolyte solution used in the preparation of the positive electrode material was obtained. 5.8 g of conductive additive (carbon black) and 139.4 g of negative electrode active material (graphite) were stirred at 900 rpm for 18 seconds in a mixer (Thinky Mixer ARE-310, manufactured by Thinky Corporation) to obtain a mixture (145.2 g). 54.8 g of electrolyte solution was added to the mixture (145.2 g), and the mixture was stirred at 900 rpm for 30 seconds in a mixer (Thinky Mixer ARE-310, manufactured by Thinky Corporation) to obtain a negative electrode material. The volume ratio of the solid component to the liquid component of the obtained negative electrode material was 61:39.

[0119] [Example 1] 20 g of positive electrode material was placed in a metal cylinder with an inner diameter of 20 mm, and a metal cylinder with an outer diameter of 19.8 mm was placed on top of it and pressed to form a cylindrical shape (consolidation process). A metal blade (length in the conveying direction: 80 mm) was installed so that the distance T1, distance T2, and angle θ (see Figure 1) were the values ​​listed in Table 1. Aluminum foil was attached to the support carrier as a support. The cylindrically compacted positive electrode material was placed on the aluminum foil, and the carrier was conveyed in the direction of the metal blade at a conveying speed of 5 m / min to supply the positive electrode material into the gap between the blade and the aluminum foil (electrode material supply process). The supplied positive electrode material was smoothed with the blade to form a positive electrode layer (electrode layer formation process). The thickness of the positive electrode layer was 0.6 mm. Point defects were present in the positive electrode layer after one film formation. The formed positive electrode layer was subjected to a blade smoothing process several times, resulting in the formation of a continuous film free of point defects.

[0120] Example 2: 20 g of positive electrode material was consolidated using an extrusion molding machine (using a screw and punching plate) and fragmented into cylindrical shapes with a diameter of 1 mm (consolidation process, electrode material fragmentation process). A metal blade (length in the conveying direction: 80 mm) was installed so that the distance T1, distance T2, and angle θ were the values ​​listed in Table 1. Aluminum foil was attached as a support to a support conveyance table. The cylindrically fragmented positive electrode material was placed on the aluminum foil, and the conveyance table was conveyed in the direction of the metal blade, supplying the positive electrode material into the gap between the blade and the aluminum foil (electrode material supply process). The supplied positive electrode material was smoothed with the blade to form a positive electrode layer (electrode layer formation process). The thickness of the positive electrode layer was 0.4 mm. Point defects were present in the positive electrode layer after a single film formation. The formed positive electrode layer was subjected to the blade smoothing process multiple times, resulting in the formation of a continuous film without point defects.

[0121] [Example 3] Film formation was performed in the same manner as in Example 2, except that the distance T1 and angle θ of the metal blade were changed to the values ​​shown in Table 1. The thickness of the positive electrode layer was 0.4 mm. A continuous film without point defects was formed in a single film formation.

[0122] [Example 4] A film was formed in the same manner as in Example 2, except that the distance T1, angle θ, and length of the metal blade were changed to the values ​​shown in Table 1. The thickness of the positive electrode layer was 0.3 mm. A continuous film without point defects was formed in a single film formation.

[0123] [Example 5] 15 g of negative electrode material was consolidated using an extrusion molding machine (using a screw and punching plate) and fragmented into cylindrical shapes with a diameter of 3 mm (consolidation process, electrode material fragmentation process). A metal blade (length in the conveying direction: 80 mm) was installed so that the distance T1, distance T2, and angle θ were the values ​​listed in Table 1. Copper foil (surface roughness Ra: μm) was attached as a support to the support conveying table. The cylindrically fragmented negative electrode material was placed on the copper foil, and the conveying table was conveyed in the direction where the metal blade was installed, and the negative electrode material was supplied into the gap between the blade and the copper foil (electrode material supply process). The supplied negative electrode material was smoothed with the blade to form a negative electrode layer (electrode layer formation process). The thickness of the negative electrode layer was 0.3 mm. A continuous film without point defects was formed in a single film formation.

[0124] [Example 6] A film was formed in the same manner as in Example 5, except that the copper foil (surface roughness Ra: 0.6 μm) was replaced with a copper foil (surface roughness Ra: 0.2 μm). The thickness of the negative electrode layer was 0.3 mm. A continuous film without point defects was formed in a single film formation.

[0125] [Example 7] A film was formed in the same manner as in Example 5, except that the copper foil (surface roughness Ra: 0.6 μm) was replaced with a polyethylene separator. The thickness of the negative electrode layer was 0.3 mm. A continuous film without point defects was formed in a single film formation.

[0126] [Comparative Example 1] A metal blade (length in the conveying direction: 80 mm) was installed so that the distance T1, distance T2, and angle θ were the values ​​listed in Table 1. Aluminum foil was attached as a support to the support conveying table. 20 g of uncompacted, amorphous positive electrode material was placed on the aluminum foil, and the conveying table was conveyed in the direction where the metal blade was installed, and the positive electrode material was supplied into the gap between the blade and the aluminum foil (electrode material supplying step). The supplied positive electrode material did not adhere to the aluminum foil, and no film could be formed.

[0127] [Comparative Example 2] A metal blade (length in the conveying direction: 80 mm) was installed so that the distance T1, distance T2, and angle θ were the values ​​listed in Table 1. Copper foil (surface roughness Ra: 0.6 μm) was attached as a support to the support conveying table. 15 g of uncompacted, amorphous negative electrode material was placed on the copper foil, and the conveying table was conveyed in the direction where the metal blade was installed, supplying the negative electrode material into the gap between the blade and the copper foil (electrode material supplying step). The supplied negative electrode material did not adhere to the copper foil, and no film could be formed.

[0128] Adhesion and coating properties were evaluated for Examples 1 to 7 and Comparative Examples 1 and 2. The evaluation methods were as follows.

[0129] <Adhesion> After the electrode material supplying step, the adhesion of the electrode material to the support was evaluated based on the following evaluation criteria. A: A continuous film free of point defects was formed in one film formation. B: A continuous film free of point defects was formed in multiple film formations. C: Film formation was not possible.

[0130] <Coatability> The coatability of the electrode material was evaluated based on the following evaluation criteria. The closer the thickness of the electrode layer is to 0.3 mm, the smaller the coating load is. A: The thickness of the electrode layer is 0.3 mm or more and less than 0.36 mm. B: The thickness of the electrode layer is 0.36 mm or more and less than 0.42 mm. C: The thickness of the electrode layer is 0.42 mm or more.

[0131] The evaluation results are shown in Table 1. In Table 1, aluminum foil is represented as "Al foil" and copper foil is represented as "Cu foil." When a compaction step was performed, it was represented as "Y," and when a compaction step was not performed, it was represented as "N." When an electrode material subdivision step was performed, it was represented as "Y," and when an electrode material subdivision step was not performed, it was represented as "N." The diameter of the subdivided electrode material was also recorded. The degree of saturation was measured using a vernier caliper method. In Examples 1 to 7, the degree of saturation of the compacted electrode material was recorded, and in Comparative Examples 1 and 2, the degree of saturation of the prepared electrode material was recorded.

[0132]

[0133] As shown in Table 1, Examples 1 to 7 include the steps of mixing and compacting an electrode material containing an electrolyte, an electrode active material, and a conductive additive, supplying the compacted electrode material into the gap between the support being transported and the blade, and leveling the supplied electrode material with the blade to form an electrode layer. It was found that the compacted electrode material had a degree of saturation of 80% or more and therefore had excellent adhesion.

[0134] In Comparative Examples 1 and 2, the compaction step was not carried out, and an electrode layer could not be formed.

[0135] In Example 2, the electrode material was subdivided, and therefore it was found that the coating properties were superior compared to Example 1.

[0136] In Example 3, the angle θ was 1° to 15°, and it was found that the adhesion was superior to that of Example 2.

[0137] In Example 4, the distance T1 was 1 mm to 20 mm, and it was found that the adhesion was superior to that of Example 3.

[0138] In Example 6, a copper foil having a surface roughness Ra of 1.0 μm or less was used as the support. When a copper foil having a surface roughness Ra of 1.0 μm or less was used, the electrode material was difficult to adhere to in the conventional manufacturing method. However, in Example 6, it was found that the adhesion was excellent, similar to Example 5.

[0139] In Example 7, a separator was used as the support. In conventional manufacturing methods, it was difficult to form an electrode layer by adhering an electrode material to a separator, but in Example 7, it was found that, like in Example 5, excellent adhesion was achieved.

[0140] Next, a bi-cell battery was fabricated. 20 g of negative electrode material was consolidated using an extrusion molding machine (using a screw and punching plate) and fragmented into cylindrical shapes with a diameter of 3 mm (consolidation process, electrode material fragmentation process). A metal blade (width: 210 mm, length in the conveying direction: 80 mm) was installed so that the angle θ was 10°, the distance T1 was 14.2 mm, and the distance T2 was 0.3 mm. A polyethylene separator (width: 220 mm, length in the conveying direction: 160 mm) was attached to the support carrier. The cylindrically fragmented negative electrode material was placed on copper foil, and the carrier was transported in the direction of the metal blade at a transport speed of 5 m / min, supplying the negative electrode material into the gap between the blade and the separator (electrode material supply process). The supplied negative electrode material was leveled with the blade to form a negative electrode layer (electrode layer formation process). The negative electrode layer had a thickness of 0.3 mm, a length of 150 mm, and a width of 200 mm. Two separators each having a negative electrode layer formed thereon were produced.

[0141] 25 g of positive electrode material was compacted using an extrusion molding machine (using a screw and punching plate) and fragmented into cylindrical shapes with a diameter of 1 mm (compaction process, electrode material fragmentation process). A metal blade (width: 210 mm, length in the conveying direction: 40 mm) was installed so that the angle θ was 15°, the distance T1 was 10.7 mm, and the distance T2 was 0.3 mm. An aluminum foil (width: 200 mm, length in the conveying direction: 150 mm) laminated with resin on one side was attached to a conveying table with the exposed aluminum side facing up. The cylindrically fragmented positive electrode material was placed on the aluminum foil, and the conveying table was conveyed in the direction of the metal blade at a conveying speed of 5 m / min, and the positive electrode material was supplied into the gap between the blade and the aluminum foil (electrode material supplying process). The supplied negative electrode material was leveled with the blade, and a positive electrode layer was formed (electrode layer forming process). The negative electrode layer had a thickness of 0.3 mm, a length of 150 mm, and a width of 200 mm. Two pieces of aluminum foil on which a positive electrode layer was formed were prepared.

[0142] A separator with a negative electrode layer formed thereon was laminated on the aluminum foil with a positive electrode layer formed thereon, so that the separator side and the positive electrode layer were in contact with each other. Copper foil (width: 200 mm, length: 150 mm) was laminated on the negative electrode layer. A separator with a negative electrode layer formed thereon was laminated on the copper foil, so that the copper foil and the negative electrode layer were in contact with each other. Aluminum foil with a positive electrode layer formed thereon was laminated on the separator, so that the positive electrode layer and the separator were in contact with each other. This resulted in a bi-cell battery laminated in the following order: aluminum foil / positive electrode / separator / negative electrode / copper foil / negative electrode / separator / positive electrode / aluminum foil.

[0143] The margin of the resin laminate on one side of the aluminum foil was heat-sealed to the margin of the separator, and then a charge-discharge test was conducted.The resulting bi-cell battery was confirmed to have the battery capacity of two single-layer batteries.

[0144] The disclosure of Japanese Patent Application No. 2024-052431, filed on March 27, 2024, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated to be incorporated by reference.

Claims

1. A method for manufacturing a quasi-solid-state battery, comprising the steps of: mixing and compacting an electrode material containing an electrolyte, an electrode active material, and a conductive additive; supplying the compacted electrode material into a gap between a conveyed support and a blade; and smoothing the supplied electrode material with the blade to form an electrode layer on the support, wherein the compacted electrode material has a degree of saturation of 80% or more.

2. The method for producing a quasi-solid-state battery according to claim 1, further comprising a step of comminuted the compacted electrode material to obtain a plurality of comminuted electrode materials, and supplying the plurality of comminuted electrode materials into the gap between the support and the blade.

3. The method for manufacturing a quasi-solid battery according to claim 1 or 2, wherein the angle formed between the direction in which the support is transported and the surface of the blade facing the support is 1° to 15°.

4. The method for manufacturing a quasi-solid battery according to claim 1 or 2, wherein the shortest distance between the upstream tip of the blade in the conveying direction of the support and the support is 1 mm to 20 mm.

5. The method for producing a quasi-solid battery according to claim 1 or 2, wherein the electrode layer is a negative electrode layer containing graphite as the electrode active material.

6. The method for manufacturing a quasi-solid battery according to claim 1 or 2, wherein the support is a copper foil having a surface roughness Ra of 0.2 μm or less.

7. The method for producing a quasi-solid battery according to claim 1 or 2, wherein the support is a separator.

8. A method for producing a quasi-solid-state battery according to claim 1 or claim 2, wherein a negative electrode layer is formed on a separator as the support, and the separator side on which the negative electrode layer is formed is placed on a positive electrode layer formed on a current collecting foil, thereby producing a bi-cell battery.

9. The method for producing a quasi-solid-state battery according to claim 8, wherein the negative electrode layer is formed on both sides of a copper foil to produce a bi-cell battery.

10. A method for producing a quasi-solid-state battery according to claim 1 or claim 2, wherein a negative electrode layer is formed on a separator as the support, and the separator side on which the negative electrode layer is formed is placed on a positive electrode layer formed on a current collecting foil, thereby producing a bipolar battery.

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