Method for manufacturing quasi-solid-state battery

Abstract

This method for manufacturing a quasi-solid battery includes the steps of: supplying an electrode material containing an electrolyte and an electrode active material onto a support; applying the supplied electrode material to the support to form an electrode layer; and adding an electrolyte to the electrode layer. The electrode material has a degree of saturation of 60% to 90%.

Description

Method for manufacturing a quasi-solid battery

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

[0002] In recent years, from the viewpoint of safety, studies on quasi-solid batteries in which part of the electrolyte is replaced with a solid electrolyte have been underway. In the manufacture of a battery electrode using a powder containing an electrode active material, generally, a step of applying an electrode material containing an electrode active material or the like, which is a powder, onto a support is included.

[0003] For example, Japanese Patent Application Laid-Open No. 2017-533548 describes a method for manufacturing an electrochemical cell, including a step of coating a semi-solid cathode on a first surface of a positive current collector, a step of coating a semi-solid anode on a first surface of a negative current collector, a step of disposing a separator between the semi-solid cathode and the semi-solid anode, a step of disposing the positive current collector, the negative current collector, and the separator in a pouch, and a step of sealing the pouch to form the electrochemical cell. Japanese Patent Application Laid-Open No. 2021-530829 describes a method including continuously distributing 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 a completed electrode.

[0004] When the saturation degree of the electrode material is high, evaporation of the electrolyte during the manufacturing process and desorption of the electrolyte from the electrode material due to solid-liquid separation by pressurization are likely to occur, which may lead to variations in the electrode layer composition and deterioration of battery performance.

[0005] Therefore, the problem to be solved by one embodiment of the present disclosure is made in view of the above circumstances, and to provide a method for manufacturing a quasi-solid battery that suppresses loss of the electrolyte during manufacturing and is excellent in composition stability and battery performance.

[0006] The present disclosure includes the following aspects. <1> A method for manufacturing a quasi-solid battery, comprising: a step of supplying an electrode material containing an electrolytic solution and an electrode active material onto a support; a step of coating the supplied electrode material onto the support to form an electrode layer; and a step of adding an electrolytic solution to the electrode layer, wherein the electrode material has a saturation of 60% to 90%. <2> The method for manufacturing a quasi-solid battery according to <1>, wherein in the step of adding an electrolytic solution, an amount of electrolytic solution is added such that it is 10% to 50% by mass with respect to the total amount of the electrolytic solution contained in the quasi-solid battery. <3> The method for manufacturing a quasi-solid battery according to <1> or <2>, further comprising a step of disposing a separator on the formed electrode layer, and in the step of adding an electrolytic solution, adding the electrolytic solution onto the separator. <4> The method for manufacturing a quasi-solid battery according to <3>, further comprising a step of leveling the surface roughness Sa of the surface of the electrode layer to 1 μm or less after forming the electrode layer and before disposing the separator. <5> The method for manufacturing a quasi-solid battery according to any one of <1> to <4>, wherein the step of adding an electrolytic solution is performed by spraying the addition of the electrolytic solution.

[0007] According to an embodiment of the present disclosure, there is provided a method for manufacturing a quasi-solid battery that suppresses loss of an electrolytic solution during manufacturing and has excellent battery performance.

[0008] Hereinafter, embodiments of the method for manufacturing a quasi-solid battery will be described. However, the present disclosure is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present disclosure.

[0009] In this disclosure, numerical ranges indicated using "~" mean a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Also, in numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the value shown in the example. The elements in each drawing shown in this disclosure are not necessarily to exact scale, and the focus is on clearly illustrating the principles of this disclosure, with some areas being emphasized. In addition, in each drawing, components having the same function are denoted by the same reference numeral, and redundant explanations are omitted. In this disclosure, a combination of two or more preferred forms or embodiments is a more preferred form or embodiment. "Semi-solid battery" means a secondary battery having an electrode layer in which an electrolyte is mixed with an electrode active material.

[0010] The method for manufacturing a quasi-solid battery according to this disclosure includes a step of supplying an electrode material containing an electrolyte and an electrode active material onto a support (hereinafter also referred to as the "electrode material supply step"), a step of coating the supplied electrode material onto the support to form an electrode layer (hereinafter also referred to as the "electrode layer formation step"), and a step of adding an electrolyte to the electrode layer (hereinafter also referred to as the "electrolyte addition step"), wherein the electrode material has a saturation level of 60% to 90%.

[0011] Conventionally, when the saturation of the electrode material is high, evaporation of the electrolyte and desorption of the electrolyte from the electrode material due to solid-liquid separation under pressure are likely to occur during manufacturing processes such as supplying the electrode material, film formation, and drying. When the electrolyte decreases during the manufacturing process, battery performance tends to deteriorate. The manufacturing method for a quasi-solid battery according to this disclosure can suppress evaporation of the electrolyte and desorption of the electrolyte from the electrode material due to solid-liquid separation under pressure by setting the saturation of the electrode material initially supplied to the support to 60% to 90%. Setting the saturation of the electrode material initially supplied to the support to 60% to 90% means deliberately reducing the amount of electrolyte that should be contained in the electrode material. By reducing the amount of electrolyte in the initial stage and including a step of adding electrolyte to the electrode layer, it is possible to secure the predetermined electrolyte content in the quasi-solid battery in the final form, resulting in superior battery performance.

[0012] Japanese Patent Publication No. 2017-533548 and Japanese Patent Publication No. 2021-530829 do not contain any descriptions regarding combinations of electrode material supply process, electrode layer formation process, and electrolyte addition process.

[0013] <Electrode Material Supply Process> In the electrode material supply process, electrode material containing electrolyte and electrode active material is supplied onto a support.

[0014] The method of supplying the electrode material onto the support is not particularly limited. For example, the electrode material may be supplied continuously or intermittently from a tank storing the electrode material to the upstream side in the transport direction of the support.

[0015] (Support) The support can be appropriately selected depending on the type of quasi-solid battery to be manufactured. The support may be a metal foil.

[0016] The thickness of the metal foil is preferably 15 μm or less, and 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.

[0017] The thickness of the metal foil is measured using the following method: A small piece of the metal foil is cut out and measured using a micrometer (product name "High-Precision Digimatic Micrometer MDH-25MC", manufactured by Mitutoyo Corporation).

[0018] The width and length of the metal foil should be set appropriately from the perspective of application to the roll-to-roll method and the desired width and length of the electrode sheet.

[0019] Examples of metals that make up the metal foil include copper, aluminum, silver, gold, and alloys thereof. Alternatively, the metals that make up the metal foil may be stainless steel, nickel, titanium, or Invar alloy.

[0020] In particular, considering the dimensional stability and track record of use as a metal foil, aluminum foil is preferred for the positive electrode, and copper foil is preferred for the negative electrode.

[0021] From the viewpoint of surface treatment costs, 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.

[0022] Surface roughness Ra refers to the arithmetic mean roughness. Surface roughness Ra is measured using an atomic force microscope (AFM).

[0023] From the above viewpoint, the support is preferably a copper foil with a surface roughness Ra of 0.2 μm or less.

[0024] The support may be a separator. The separator can be any conventionally known separator used in semi-solid-state or all-solid-state batteries. Examples of separators include porous membranes containing resin materials such as polyethylene, polypropylene, polybutene, polyvinyl chloride, polyethylene terephthalate, polyethersulfone, polyamide, polyimide, polyimidoamide, polyaramid, polycycloolefin, nylon, and polytetrafluoroethylene.

[0025] The thickness of the separator is, for example, 0.5 μm to 40 μm.

[0026] The support is placed, for example, on a moving stage provided in the manufacturing apparatus. By moving the moving stage in the transport direction, the support is transported in the transport direction. The transport speed of the support is not particularly limited, and is, for example, 1 m / min to 20 m / min.

[0027] (Electrode material) The electrode material comprises at least an electrolyte and an electrode active material, and may contain other components as needed.

[0028] -Electrolyte- The electrode material includes an electrolyte. The electrolyte is not particularly limited, and known electrolytes can be used. Examples of electrolytes include those containing an electrolyte and a solvent. Specific examples of electrolytes include those containing a lithium salt compound as the electrolyte and a carbonate compound as the solvent.

[0029] Examples of lithium salt compounds include lithium hexafluorophosphate. The electrolyte may contain one lithium salt compound or two or more lithium salt compounds.

[0030] Examples of carbonate compounds include linear carbonate compounds such as ethylmethyl carbonate (also known as EMC), dimethyl carbonate (also known as DMC), and diethyl carbonate (DEC), and cyclic carbonate compounds such as ethylene carbonate (also known as EC) and propylene carbonate (also known as PC). The electrolyte may contain a single carbonate compound, a combination of two or more carbonate compounds, or a combination of one or more linear carbonate compounds and one or more cyclic carbonate compounds.

[0031] As the electrolyte contained in the electrolyte solution, for example, known inorganic solid electrolytes can also be used.

[0032] For example, an ionic liquid may be used as a component of the electrolyte. The ionic liquid may be used as either an electrolyte or a solvent.

[0033] The electrolyte content relative to the total volume of the electrode material is preferably 70% by volume or less, but may be 50% by volume or less, or 40% by volume or less. The lower limit of the electrolyte content 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. For example, the electrolyte content relative to the total volume of the electrode material is 30% by volume to 50% by volume.

[0034] - Electrode Active Material - An electrode active material is a substance capable of inserting and releasing ions of metallic elements belonging to Group 1 or Group 2 of the periodic table. Electrode active materials are contained within a solid component. Examples of electrode active materials include positive electrode active materials and negative electrode active materials.

[0035] The positive electrode active material is not limited, and any known electrode active material used in positive electrodes can be used. Preferably, the positive electrode active material is one that can reversibly insert and release lithium ions.

[0036] Examples of positive electrode active materials include transition metal oxides and elements that can be compounded with lithium (e.g., sulfur). Among these, the positive electrode active material is preferably a transition metal oxide.

[0037] The transition metal oxide is preferably a transition metal oxide containing at least one transition metal element selected from the group consisting of Co (cobalt), Ni (nickel), Fe (iron), Mn (manganese), Cu (copper), and V (vanadium) (hereinafter referred to as "element Ma").

[0038] When the transition metal oxide contains Li and element Ma, the molar ratio of Li to Ma (Li / Ma) is preferably 0.3 to 2.2.

[0039] Furthermore, the transition metal oxide may contain at least one transition metal element (hereinafter referred to as "element Mb") selected from the group consisting of elements from Group 1 other than lithium, elements from Group 2, 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 substance of element Ma.

[0040] 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 halogenated phosphate compounds, and lithium-containing transition metal silicate compounds.

[0041] As transition metal oxides having a layered rock salt structure, for example, LiCoO ２ (lithium cobaltate [LCO]), LiNi ２ O ２ (lithium nickelate), LiNi ０．８５ Co ０．１０ Al ０．０５ O ２ (lithium nickel cobalt 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 nickelate) can be mentioned.

[0042] As transition metal oxides having a spinel structure, for example, 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 can be mentioned.

[0043] As lithium-containing transition metal phosphate compounds, for example, olivine-type iron phosphate salts (for example, LiFePO ４ , and Li ３ Fe ２ (PO ４ ) ３ ), pyrophosphate iron salts (for example, LiFeP ２ O ７ ), cobalt phosphate salts (for example, LiCoPO ４ ), monoclinic NASICON-type vanadium phosphate salts (for example, Li ３ V ２ (PO ４ ) ３ (lithium vanadium phosphate)) can be mentioned.

[0044] Examples of lithium-containing transition metal halide phosphate compounds include iron fluoride phosphates (e.g., Li ２ FePO ４ F), manganese phosphate fluoride (e.g., Li ２ MnPO ４ F), and cobalt fluoride phosphate salts (e.g., Li ２ CoPO ４ F) is one example.

[0045] Examples of lithium-containing transition metal silicate compounds include Li ２ FeSiO ４ Li ２ MnSiO ４ , and Li ２ CoSiO ４ These are some examples.

[0046] The transition metal oxide is preferably a transition metal oxide having a layered rock salt type structure, such as LiCoO ２ (Lithium cobalt oxide [LCO]), LiNi ０．８５ Co ０．１０ Al ０．０５ O ２ (Lithium nickel-cobalt aluminate [NCA]), and LiNi １／３ Co １／３ Mn １／３ O ２ It is more preferable that the compound is at least one compound selected from the group consisting of (lithium nickel manganese cobalt oxide [NMC]).

[0047] The positive electrode active material may be a commercially available product or a synthetic product manufactured by a known method (e.g., calcination). For example, a positive electrode active material obtained by calcination 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.

[0048] The shape of the positive electrode active material is not limited, but from the viewpoint of handling, it is preferable to be in particulate form.

[0049] 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. Preferably, the volume-average particle size of the positive electrode active material is 0.3 μm to 40 μm, and more preferably 0.5 μm to 30 μm. A volume-average particle size of 0.3 μm or more of the positive electrode active material can suppress scattering of the positive electrode active material during handling. A volume-average particle size of 40 μm or less of the positive electrode active material can easily adjust the thickness of the electrode layer and suppress the generation of voids during the molding process.

[0050] The volume-average particle size of the positive electrode active material is measured by the following method: A dispersion containing 0.1% by 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 the measurement sample. Using a laser diffraction / scattering particle size distribution analyzer (e.g., LA-960 manufactured by Horiba, Ltd.), data is acquired 50 times under conditions 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 taken as the volume-average particle size of the positive electrode active material. For other detailed conditions, refer to "JIS Z 8828:2013" as needed.

[0051] Methods for adjusting the particle size of the positive electrode active material include, for example, using a pulverizer, crusher, or classifier. Alternatively, known milling methods may be applied to adjust the particle size of the positive electrode active material.

[0052] The positive electrode active material may be used alone or in combination of two or more types. Furthermore, even when using only one type of positive electrode active material, it may be used in combination with positive electrode active materials of different particle sizes.

[0053] 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.

[0054] The negative electrode active material is not limited, and any known negative electrode active material used in negative electrodes can be used. Preferably, the negative electrode active material is one that can reversibly insert and release lithium ions.

[0055] Examples of negative electrode active materials include carbonaceous materials, metal oxides (e.g., tin oxide), silicon oxide, metal composite oxides, elemental lithium, lithium alloys (e.g., lithium aluminum alloys), and metals capable of forming alloys with lithium (e.g., Sn, Si, and In). Among these, from the viewpoint of reliability, the negative electrode active material is preferably a carbonaceous material or a lithium composite oxide.

[0056] Carbonaceous materials are materials that consist substantially 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, cellulosic 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 plate-shaped graphite. In this disclosure, "plate-shaped" means a shape having two main planes facing in opposite directions.

[0057] In particular, from a practical standpoint, it is preferable that the negative electrode active material contains graphite.

[0058] The metal composite oxide is preferably a metal composite oxide capable of intercalating and releasing lithium. From the viewpoint of high current density charge-discharge characteristics, the lithium-capable metal composite oxide preferably contains at least one element selected from the group consisting of titanium and lithium.

[0059] Metal oxides and metal composite oxides are preferably amorphous oxides.

[0060] The metal oxide and metal composite oxide are preferably chalcogenides. Chalcogenides are reaction products of a metal element and an element of Group 16 in the periodic table.

[0061] Among the group of compounds consisting of amorphous oxides and chalcogenides, amorphous oxides and chalcogenides of metalloid elements are preferred, and oxides containing at least one element selected from the group consisting of elements from groups 13 to 15 of the periodic table, Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi, as well as chalcogenides, are more preferred.

[0062] The negative electrode active material may also preferably contain titanium. Because the volume fluctuation during lithium ion intercalation and deintercalation is small, it exhibits excellent rapid charge-discharge characteristics. Furthermore, because electrode degradation is suppressed, it is possible to improve the lifespan of lithium-ion secondary batteries. Therefore, a negative electrode active material containing titanium is preferable. ４ Ti ５ O １２ (Lithium titanate [LTO]) is preferred.

[0063] The negative electrode active material may be a commercially available product or a synthetic product manufactured by a known method (e.g., calcination). For example, a negative electrode active material obtained by calcination may be washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

[0064] The negative electrode active material is available, for example, as CGB20 (Nippon Graphite Industries Co., Ltd.).

[0065] The composition of the negative electrode active material is measured using inductively coupled plasma (ICP) emission spectroscopy.

[0066] The shape of the negative electrode active material is not limited, but it is preferable that it be in particulate form from the viewpoint of ease of handling and ease of controlling uniformity during mass production.

[0067] 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 described above.

[0068] Methods for adjusting the particle size of the negative electrode active material include, for example, using a pulverizer or a classifier.

[0069] The negative electrode active material may be used alone or in combination of two or more types. Furthermore, even when using only one type of negative electrode active material, a combination of negative electrode active materials with different particle sizes may be used.

[0070] 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.

[0071] 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 surface coating agents include metal oxides containing Ti, Nb, Ta, W, Zr, Si, or Li. Examples of the above metal oxides include spinel titanate, tantalum oxides, niobium oxides, and lithium niobate compounds.

[0072] -Conductive additive- From the viewpoint of improving the electronic conductivity of the electrode active material, the electrode material preferably contains a conductive additive. The conductive additive is not limited, and known conductive additives can be used. The conductive additive is contained in the solid component.

[0073] 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).

[0074] The conductive additive may be used alone or in combination of two or more types. The content of the conductive additive relative to the total volume of the electrode material is preferably 0.05% to 5% by volume, more preferably 0.1% to 4% by volume, and even more preferably 0.5% to 3% by volume. In the method for manufacturing a quasi-solid battery according to this disclosure, it is preferable that the amount of conductive additive used be determined so that the content in the electrode layer falls within the above range.

[0075] -Solvent- The electrode material may contain, as a liquid component, a solvent other than the solvent included as a component of the electrolyte (hereinafter also simply referred to as "solvent"). Examples of solvents 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.

[0076] The boiling point of the solvent is preferably 50°C or higher, and more preferably 70°C or higher, at normal pressure (i.e., 1 atmosphere). The upper limit of the boiling point of the solvent is preferably 250°C or lower, and more preferably 220°C or lower, at normal pressure (i.e., 1 atmosphere).

[0077] The solvent may be used alone or in combination of two or more types. The content of the liquid component (i.e., electrolyte and solvent) relative to the total volume of the electrode material is preferably 70% by volume or less, but may also be 50% by volume or less, or 40% by volume or less. The lower limit of the content of the liquid component 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 liquid component relative to the total volume of the electrode material is preferably 30% by volume to 50% by volume.

[0078] -Other Components- In addition to the above components, the electrode material may also contain inorganic solid electrolytes, binders, dispersants, and other additives. From the viewpoint of improving energy density, the electrode material preferably has a low binder (also called resin component) content, preferably 1% by mass or less, and particularly preferably no binder (0% by mass). The binder includes components called resin components, rheology modifiers, and dispersants, such as fluororesins, hydrocarbon thermoplastics, acrylic resins, and urethane resins. Examples of dispersants include known dispersants that can disperse the target material. As for other additives, known additives added to electrodes can be used.

[0079] - Saturation Level - The electrode material used in this disclosure has a saturation level of 60% to 90%, preferably 80% to 90%. If the saturation level is 60% or higher, the electrode layer tends to be more uniform, suppressing an increase in internal resistance within the quasi-solid battery and resulting in superior battery performance. If the saturation level is 90% or lower, the dehydration of the electrolyte during the manufacturing process is suppressed, resulting in superior battery performance.

[0080] In this disclosure, the degree of saturation refers to the proportion of the voids occupied by the electrolyte within the solid content. The degree of saturation can be measured using the caliper method, which is common 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 solid content in electrode material (g / cm³) ３ ) e: Gap ratio ρ ｗ: Density of electrolyte (g / cm³) ３ )

[0081] The water content is expressed by the following formula: ω = (m ｗ / m ｓ ) × 100 m ｗ : Mass (g) of electrolyte in electrode material ｓ : Mass (g) of solid content in electrode material

[0082] The void ratio is calculated by the following method: Fill a cylinder with a fixed inner diameter with m (g) of electrode material. Using a cylinder paired with the cylinder, measure the filled electrode material in a volume of V (cm³). ３ It is compacted to the following degree. The wet density of the electrode material is expressed by the following formula: ρ ｔ = m / V The dry density of the electrode material is expressed by the following formula: ρ ｄ = ρ ｔ ÷{1+(ω / 100)} e=(ρ ｓ / ρ ｄ )-1

[0083] <Electrode Layer Formation Process> The method for manufacturing a quasi-solid battery according to this disclosure involves coating a supplied electrode material onto a support to form an electrode layer. The method for coating the supplied electrode material onto the support is not particularly limited, but it is preferable to smooth the electrode material with a blade before coating the support.

[0084] The blade is a plate-shaped component with a flat surface. The shape, size, and material of the contact portion that comes into contact with the electrode material should be appropriately selected according to the type of electrode material (type of electrode active material, solid content concentration, electrolyte composition (viscosity, surface tension), etc.), the size and thickness of the target electrode layer, etc.

[0085] The contact portion of the blade with the electrode material is preferably such that the electrode material does not adhere easily. For example, it is preferable that at least the contact portion of the blade exhibits release properties. The blade may be made of, for example, a resin (fluoropolymer such as polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), etc.), a metal (stainless steel, aluminum, iron, cemented carbide, etc.), or a ceramic. Furthermore, from the viewpoint of providing release properties to the surface of the contact portion of the blade, the blade may have a surface layer that exhibits release properties (for example, a surface layer containing fluoropolymer resin, a surface layer containing silicon-based particles and resin). In addition, from the viewpoint of improving 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.

[0086] To increase the output of a battery, it is desirable to increase the specific surface area, so a thinner electrode layer is preferable. On the other hand, to increase the capacity of a battery, it is desirable to increase the amount of electrode material per unit volume, so a thicker electrode layer is preferable. To achieve both high output and high capacity, the electrode layer thickness is preferably 30 μm to 400 μm, and more preferably 100 μm to 300 μm.

[0087] The electrode layer thickness is measured by the following method: A non-contact laser displacement meter (Keyence Corporation, multi-color laser coaxial displacement meter, CL-3000) is used to measure the surface height of the support before coating and the surface height of the electrode layer after coating. The thickness is then determined by subtracting the surface height of the support from the surface height of the electrode layer.

[0088] If the electrode material contains a negative electrode active material as the electrode active material, a negative electrode layer is formed as the electrode layer. If the electrode material contains a positive electrode active material as the electrode active material, a positive electrode layer is formed as the electrode layer.

[0089] In the method for manufacturing a quasi-solid battery according to this disclosure, both a negative electrode layer and a positive electrode layer can be formed.

[0090] For example, a first electrode layer (e.g., a negative electrode layer) may be formed on a first support, and a second electrode layer (e.g., a positive electrode layer) may be formed on a second support. By placing a separator between the negative electrode layer and the positive electrode layer, a quasi-solid battery can be manufactured comprising the first support, negative electrode layer, separator, positive electrode layer, and second support in this order.

[0091] <Electrolyte Addition Process> In the electrolyte addition process, an electrolyte is added to the electrode layer. The method of adding the electrolyte to the electrode layer is not particularly limited; it may be added directly to the electrode layer, or it may be added indirectly.

[0092] Alternatively, the electrolyte may be dispensed dropwise to multiple points on the surface of the electrode layer using an instrument such as a micropipette.

[0093] From the viewpoint of adding the electrolyte more uniformly, it is preferable to add the electrolyte by spraying. Spraying can be carried out using a commonly known sprayer.

[0094] In a first embodiment, the electrolyte may be directly added to the surface of the electrode layer. For example, by directly adding the electrolyte to the surface of the negative electrode layer formed on the first support, the electrolyte penetrates into the negative electrode layer. By placing a separator on the negative electrode layer and then placing the positive electrode layer on the separator, the electrolyte added to the negative electrode layer can be allowed to penetrate into the positive electrode layer via the separator.

[0095] In a second embodiment, a separator may be placed on the electrode layer and an electrolyte may be added on the separator. For example, a separator may be placed on the side of the negative electrode layer formed on the first support that is opposite to the first support, and an electrolyte may be added on the separator. This allows the electrolyte to permeate into the negative electrode layer via the separator. Furthermore, if the positive electrode layer is placed on the separator, the electrolyte added on the separator can permeate into the positive electrode layer. Compared to the first embodiment, the second embodiment is preferable in that it can suppress surface roughening of the electrode layer due to the addition of the electrolyte.

[0096] In a third embodiment, a separator may be placed on the first electrode layer and the electrolyte may be directly added to the second electrode layer. For example, a separator may be placed on the surface of the negative electrode layer formed on the first support. On the other hand, by directly adding the electrolyte to the surface of the positive electrode layer, the electrolyte penetrates into the positive electrode layer. By placing the positive electrode layer with the added electrolyte on a separator, the electrolyte added to the positive electrode layer can be allowed to penetrate into the positive electrode layer via the separator.

[0097] In the electrolyte addition step, it is preferable to add an amount of electrolyte that is 10% to 50% by mass relative to the total amount of electrolyte contained in the quasi-solid battery. If the amount added is 10% by mass or more, the increase in internal resistance within the quasi-solid battery is further suppressed. If the amount added is 50% by mass or less, the dehydration of the electrolyte is further suppressed.

[0098] From the above viewpoint, the amount added is more preferably 20% to 40% by mass.

[0099] "Electrolyte contained in a semi-solid battery" refers to all electrolytes within the semi-solid battery. For example, if a semi-solid battery includes a negative electrode layer, a positive electrode layer, and a separator, then "electrolyte contained in a semi-solid battery" refers to the electrolytes contained in the negative electrode layer, the positive electrode layer, and the separator.

[0100] The method for manufacturing a quasi-solid battery according to this disclosure may include other steps besides those described above.

[0101] As described above, in that it can suppress surface roughening of the electrode layer due to the addition of electrolyte, the method for manufacturing a quasi-solid battery according to this disclosure further includes a step of placing a separator on the formed electrode layer, and in the electrolyte addition step, it is preferable to add the electrolyte on the separator.

[0102] From the viewpoint of further improving battery performance, the method for manufacturing a quasi-solid battery according to this disclosure preferably further includes a step of leveling the surface roughness Sa of the electrode layer to 1 μm or less (hereinafter also referred to as the "surface leveling step") after the electrode layer has been formed and before the separator has been placed.

[0103] By leveling the surface roughness of the electrode layer to 1 μm or less, the contact area between the electrode layer and the separator is improved, further suppressing the increase in internal resistance within the quasi-solid battery.

[0104] From the above viewpoint, it is more preferable that the surface roughness Sa is 0.8 μm or less.

[0105] The method for leveling the surface roughness Sa of the electrode layer to 1 μm or less is not particularly limited, but one example is to level the surface of the formed electrode layer using a blade.

[0106] Examples of blades include those similar to those used in the electrode layer formation process.

[0107] In this disclosure, the surface roughness Sa is measured using a VHX-X1 microscope manufactured by Keyence Corporation.

[0108] It is preferable that the electrode materials are pre-mixed before the electrode material supply process.

[0109] The method for mixing the electrode materials is not particularly limited and may include, for example, using a ball mill, bead mill, planetary mixer, blade mixer, roll mill, kneader, or disc mill.

[0110] Furthermore, it is preferable that the mixed electrode materials are compacted before the electrode material supply step. That is, the method for manufacturing a quasi-solid battery according to this disclosure preferably further includes a step of mixing electrode materials and a step of compacting the mixed electrode materials.

[0111] The method for compacting electrode materials is not particularly limited as long as it can reduce the porosity of the electrode material. For example, compaction can be performed using a commonly known molding machine. Compaction refers to filling the voids between the powder particles of the electrode material to create a dense state.

[0112] By compacting the electrode material, the electrolyte seeps out onto the surface of the electrode material, making it easier for it to adhere to the support.

[0113] Furthermore, the method for manufacturing a quasi-solid battery according to this disclosure preferably further includes a step of subdividing a compacted electrode material to obtain a plurality of subdivided electrode materials (hereinafter also referred to as the "electrode material subdivision step").

[0114] If the process includes an electrode material subdivision step, the electrode material supply step supplies multiple subdivided electrode materials onto the support. By subdividing the electrode material beforehand and then supplying it onto the support, the force required to press the electrode material onto the support can be reduced.

[0115] The shape of the subdivided electrode material is not particularly limited and can be spherical or cylindrical, for example.

[0116] When the subdivided electrode material is spherical or cylindrical, the diameter of the cross-section is preferably 0.5 mm to 10 mm, and more preferably 1 mm to 6 mm. The diameter of the cross-section is measured by the following method: Place the electrode material on a support and measure the height with a caliper.

[0117] The method for subdividing the compacted electrode material is not particularly limited, and the electrode material may be continuously subdivided after compaction using the apparatus used for compacting the electrode material.

[0118] Alternatively, after compacting the electrode material using a device for compacting the electrode material, the compacted electrode material may be further subdivided using a separate device.

[0119] The method for manufacturing a quasi-solid-state battery according to this disclosure may involve forming a negative electrode layer on a separator as a support, and placing the separator side of the separator with the negative electrode layer on a positive electrode layer formed on a current collector foil to produce a bicell type battery. Alternatively, a bicell type battery may be produced by forming negative electrode layers on both sides of a copper foil.

[0120] Examples of bicell battery structures 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

[0121] Furthermore, the method for manufacturing a quasi-solid-state battery according to this disclosure may also involve forming a negative electrode layer on a separator as a support, and placing the separator side of the separator with the negative electrode layer on a positive electrode layer formed on a current collector foil, thereby manufacturing a bipolar battery.

[0122] Examples of bipolar battery structures 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

[0123] The present invention will be described in more detail below with reference to examples. The materials, amounts used, proportions, and details of each process shown in the following examples can be modified as appropriate, as long as they do not depart 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.

[0124] [Example 1] <Negative electrode material preparation process> -Negative electrode material- A mixture of 45 g of ethylene carbonate (EC), 10 g of propylene carbonate (PC), and 45 g of diethyl carbonate (DEC) is added to the mixture. ６ 13.4 g of (electrolyte) was mixed, and then 2.3 g of vinylene carbonate (VC) was added. Of the resulting 115.7 g of mixture, 64 g was taken out and designated as electrolyte A. Next, 159 g each of conductive additive (carbon black: "C-NERGY SUPER C45" manufactured by Imerys Graphite & Carbon) and negative electrode active material ("MESOPHASE GRAPHITE POWDER A (MGP-A)" manufactured by China Steel Chemical Corporation) were weighed out in a mass ratio of 2.7:63.4. The two were then mixed together in a mixer (Awatori Rentaro ARE-310, manufactured by Shinky Co., Ltd.) at 900 rpm for 18 seconds to prepare a kneaded mixture. Next, electrolyte A (64 g) was added to the resulting mixture (159 g), and the mixture was stirred at 900 rpm for 30 seconds using a mixer (Awatori Rentaro ARE-310, manufactured by Shinky Co., Ltd.) to obtain the negative electrode material.

[0125] <Negative Electrode Material Supply Process> A metal blade was installed, and copper foil was attached to the support conveyor table as a support. The negative electrode material, which had been compacted into a cylindrical shape, was placed on top of the copper foil, and the conveyor table was transported in the direction in which the metal blade was installed at a transport speed of 5 m / min to supply the negative electrode material to the gap between the blade and the copper foil.

[0126] <Negative electrode layer formation process> The supplied negative electrode material was leveled with a blade to form a negative electrode layer. The thickness of the negative electrode layer was approximately 0.2 mm.

[0127] <Surface leveling process> Furthermore, the negative electrode layer was leveled with a blade so that the surface roughness Sa was 1 μm or less.

[0128] <Electrolyte Addition Process> A separator was placed on the negative electrode layer, and the electrolyte was added to the separator using a micropipette. The amount of electrolyte added was 14% by mass of the design amount of electrolyte per single cell of the quasi-solid-state battery.

[0129] <Cathode Material Preparation Process> A mixture of 45 g of ethylene carbonate, 10 g of propylene carbonate, and 45 g of diethyl carbonate was mixed, to which 13.4 g of 0.9 mol / L LiPF6 solution (electrolyte) was added. Then, 2.3 g of vinylene carbonate (VC) was added to prepare electrolyte X1. 2 g of conductive additive (Ketjenbrak: "Carbon ECP600JD" manufactured by Lion Specialty Chemicals) and 174 g of cathode active material (iron phosphate: "LFP NCO M121" manufactured by Aleees) were mixed in a mixer (Awatori Rentaro ARE-310, manufactured by Thinky Co., Ltd.) at 1500 rpm (revolutions per minute) for 30 seconds to prepare compound Y1 (176 g). Electrolyte solution X1 (64g) was added to the kneaded mixture Y1 (176g), and the mixture was stirred at 1500 rpm for 120 seconds using an Awatori Rentaro (manufactured by Shinki Co., Ltd.) to obtain the cathode material.

[0130] <Cathode Material Supply Process> A metal blade was installed, and aluminum foil was attached to the support conveyor table as a support. The cathode material was placed on the aluminum foil, and the conveyor table was transported in the direction where the metal blade was installed at a transport speed of 5 m / min to supply the cathode material to the gap between the blade and the aluminum foil.

[0131] <Positive Electrode Layer Formation Process> The supplied positive electrode material was leveled with a blade to form a positive electrode layer. The thickness of the positive electrode layer was approximately 0.23 mm.

[0132] <Fabrication of a semi-solid-state battery> An aluminum foil with a positive electrode layer formed on it was placed on a separator so that the positive electrode layer and the separator were in contact, and a laminate was obtained in which copper foil, a negative electrode layer, separator, positive electrode layer, and aluminum foil were configured in this order. The four sides were heat-sealed to obtain a semi-solid-state battery.

[0133] [Example 2] A quasi-solid battery was obtained in the same manner as in Example 1, except that the following points were changed. In the electrode material preparation step, the amount of electrolyte A added was changed to achieve a saturation degree of 60% for the negative electrode material. In the electrolyte addition step, the amount of electrolyte added was set to 50% by mass.

[0134] [Example 3] A quasi-solid battery was obtained in the same manner as in Example 1, except that the following points were changed. In the electrolyte addition step, the electrolyte was added to the negative electrode layer.

[0135] [Example 4] A quasi-solid battery was obtained in the same manner as in Example 3, except that a surface leveling step was omitted.

[0136] [Example 5] A quasi-solid battery was obtained in the same manner as in Example 1, except that a surface leveling step was omitted.

[0137] [Example 6] A quasi-solid battery was obtained in the same manner as in Example 1, except that the following points were changed. In the electrolyte addition step, the amount of electrolyte added was 5% by mass.

[0138] [Example 7] A quasi-solid battery was obtained in the same manner as in Example 1, except that the following points were changed. In the electrolyte addition step, the amount of electrolyte added was 70% by mass.

[0139] [Comparative Example 1] A quasi-solid battery was obtained in the same manner as in Example 1, except that the electrolyte addition step was omitted.

[0140] [Comparative Example 2] A quasi-solid battery was obtained in the same manner as in Example 1, except that the amount of electrolyte A added in the electrode material preparation step was changed to achieve a saturation of 100% for the negative electrode material, and the electrolyte addition step was omitted.

[0141] [Comparative Example 3] A quasi-solid battery was obtained in the same manner as in Example 1, except that the following points were changed. In the electrode material preparation step, the amount of electrolyte A added was changed to achieve a saturation degree of 40% of the negative electrode material. In the electrolyte addition step, the amount of electrolyte added was set to 74% by mass.

[0142] The following evaluations were performed: <Compositional Stability> The stability of the composition of the anode material during the manufacturing process was evaluated. The smaller the ΔW below, the better the stability. Wp: Mass per unit volume of the anode material during preparation (g / cm³) ３ ) Wa: Mass per unit volume of the anode material after coating (g / cm³) ３ ) △W (%) = {(Wp - Wa) / Wp} × 100 The evaluation criteria are as follows: 5: △W is 3% or less. 4: △W is more than 3% and 5% or less. 3: △W is more than 5% and 10% or less. 2: △W is more than 10% and 20% or less. 1: △W is more than 20%.

[0143] <Uniformity of the electrode layer> The surface roughness Sa of the negative electrode layer before the separator was placed was measured using a VHX-X1 microscope manufactured by Keyence Corporation. The evaluation criteria are as follows: 5: Sa is 1 μm or less. 4: Sa is greater than 1 μm and 3 μm or less. 3: Sa is greater than 3 μm and 5 μm or less. 2: Sa is greater than 5 μm and 10 μm or less. 1: Sa is greater than 10 μm.

[0144] <Electrolyte Leakage> After bonding the positive electrode layer and the negative electrode layer with a separator in between, the presence or absence of electrolyte leakage was visually checked. A: No electrolyte leakage was found. B: Electrolyte leakage was found.

[0145] <Battery Capacity> Using the obtained semi-solid-state batteries, a CCCV charge-discharge test was performed using the TOSCAT-3000 charge-discharge test device manufactured by Toyo System Co., Ltd. The evaluation criteria are as follows: C0.3: Charge capacity at C rate 0.3 (mAh / g) C1.0: Charge capacity at C rate 1.0 (mAh / g) R1.0 / 0.3 (%) = (C1.0 / C0.3) × 100 The evaluation criteria are as follows: 5: R1.0 / 0.3 is 50% or more. 4: R1.0 / 0.3 is 40% or more and less than 50%. 3: R1.0 / 0.3 is 30% or more and less than 40%. 2: R1.0 / 0.3 is 20% or more and less than 30%. 1: R1.0 / 0.3 is less than 20%.

[0146] The evaluation results are shown in Table 1. If a surface leveling process was performed, "Y" is written in the "Surface Leveling Process" column; if the surface leveling process was not performed, "N" is written. If an electrolyte addition process was performed, "Y" is written in the "Electrolyte Addition" column; if the electrolyte addition process was not performed, "N" is written.

[0147]

[0148] As shown in Table 1, Examples 1 to 7 include the steps of supplying an electrode material containing an electrolyte and an electrode active material onto a support, coating the supplied electrode material onto the support to form an electrode layer, and adding an electrolyte to the electrode layer. Since the electrode material has a saturation level of 60% to 90%, it was found that the loss of electrolyte during manufacturing is suppressed, resulting in excellent battery performance.

[0149] In Comparative Example 1, the lack of an electrolyte addition step resulted in inferior battery performance. In Comparative Example 2, the saturation of the electrode material exceeded 90%, and an electrolyte addition step was not included. Localized electrolyte dehydration occurred during the manufacturing process, leading to variations in battery capacity results for each evaluation. The evaluation results varied within a range of 2 to 5, which can be considered a practical problem. In Comparative Example 3, the saturation of the electrode material was less than 60%, resulting in reduced uniformity of the electrode layer, increased internal resistance within the quasi-solid battery, and inferior battery performance.

[0150] In Example 1, an electrolyte was added to the separator, and it was found that the uniformity of the electrode layer was higher and the battery performance was superior compared to Example 3. In Example 1, a surface leveling process was performed, and it was found that the battery performance was superior compared to Example 5.

[0151] Furthermore, the disclosure of Japanese Patent Application No. 2024-171066, filed on September 30, 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 as being incorporated by reference.

Claims

1. A method for manufacturing a quasi-solid battery, comprising the steps of: supplying an electrode material containing an electrolyte and an electrode active material onto a support; coating the supplied electrode material onto the support to form an electrode layer; and adding an electrolyte to the electrode layer, wherein the electrode material has a saturation level of 60% to 90%.

2. The method for manufacturing a quasi-solid battery according to claim 1, wherein in the step of adding the electrolyte, an amount of electrolyte is added that is 10% by mass to 50% by mass of the total amount of electrolyte contained in the quasi-solid battery.

3. A method for manufacturing a quasi-solid battery according to claim 1 or claim 2, further comprising the step of arranging a separator on the formed electrode layer, wherein in the step of adding the electrolyte, the electrolyte is added on the separator.

4. The method for manufacturing a quasi-solid battery according to claim 3, further comprising the step of leveling the surface roughness Sa of the surface of the electrode layer to 1 μm or less after the electrode layer has been formed and before the separator has been placed.

5. The method for manufacturing a quasi-solid battery according to claim 1 or claim 2, wherein the step of adding the electrolyte is performed by spraying the electrolyte.

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