Method for manufacturing battery, and pallet

Abstract

Provided is a method for manufacturing a battery, the method comprising: a step for obtaining a first electrode laminate that includes a first film; a step for obtaining a second electrode laminate that includes a second film; a step for arranging a first electrode layer that is included in the first electrode laminate, which is fixed by means of a first pallet, and a second electrode layer that is included in the second electrode laminate, which is fixed by means of a second pallet, in predetermined positions so as to face each other with a separator being interposed therebetween; a step for forming a battery laminate on the second pallet by releasing the fixation by means of the first pallet while maintaining the fixation by means of the second pallet; and a step for thermally fusing the first film and the second film. The area of the first film is larger than that of the first electrode, the area of the second film is larger than that of the second electrode layer, and the area of the first film is larger than the area of the second film.

Description

Battery manufacturing method and pallet

[0001] The present disclosure relates to a method for manufacturing a battery and a pallet.

[0002] In recent years, various studies have been conducted on secondary batteries, and various technologies related to quasi-solid batteries, which are an example of secondary batteries, have been investigated. Quasi-solid batteries (also called semi-solid batteries) are said to be batteries with excellent LCA (Life Cycle Assessment) because they can form electrode layers without using a drying process by previously mixing an electrolyte solution with an active material and a conductive additive.

[0003] For example, Patent Document 1 describes an electrochemical cell in which a semi-solid cathode or a semi-solid anode is formed using an electrolyte solution as a process solvent and a solid content of 20% to 80% by volume, and a method for manufacturing the same. Patent Document 2 describes a method for manufacturing an electrode in which a semi-solid electrode slurry is continuously distributed onto a current collector and the distributed semi-solid electrode slurry is separated into separate portions, in which a laminate serving as a pouch is folded, individual current collectors are placed on the current collectors, the semi-solid electrode slurry is continuously applied, and the folded laminate is opened to separate the semi-solid electrode slurry into separate portions (see Patent Document 2, Figure 5).

[0004] Patent Document 1: International Publication No. 2016 / 073575 Patent Document 2: International Publication No. 2020 / 014268

[0005] Quasi-solid electrodes, which are electrode layers formed on current collector foils of positive and negative electrodes (hereinafter also referred to as positive and negative electrodes), are laminated together with a separator to form a battery. Even if quasi-solid electrodes can be produced efficiently, poor positional accuracy in laminating battery components, such as positive and negative electrodes, can cause short circuits and performance degradation in the battery.

[0006] The present disclosure has been made in consideration of the above. An object of the present disclosure is to provide a battery manufacturing method for efficiently manufacturing a battery (e.g., a quasi-solid-state battery) with excellent performance. An object of the present disclosure is to provide a pallet used in the manufacturing method for efficiently manufacturing a battery (e.g., a quasi-solid-state battery) with excellent performance.

[0007] Specific means for solving the problems include the following aspects. <1> A method for manufacturing a battery including a first electrode layer, a separator, and a second electrode layer, the method comprising the steps of: forming a first electrode layer on a surface of a first film to obtain a first electrode laminate; forming a second electrode layer on a surface of a second film to obtain a second electrode laminate; arranging the first electrode laminate fixed to a first pallet by a first pallet having a fixing function fixing the first film, and the second electrode laminate fixed to a second pallet by a second pallet having a fixing function fixing the second film, in predetermined positions where the first electrode layer and the second electrode layer face each other via the separator; releasing the fixation by the first pallet while continuing the fixation by the second pallet, and fixing both the second film and the first film to the second pallet, thereby forming a battery laminate on the second pallet in which the second electrode laminate, the separator, and the first electrode laminate are stacked in this order; and heat-sealing the first film and the second film at an end of the battery laminate fixed to the second pallet. A method for manufacturing a battery, wherein the area of ​​the first film is larger than that of the first electrode layer, the area of ​​the second film is larger than that of the second electrode layer, and the area of ​​the first film is larger than that of the second film. <2> A method for manufacturing a battery according to <1>, wherein the fixing function is a suction function, and fixing is performed by suction. <3> A method for manufacturing a battery according to <1> or <2>, wherein the first pallet and the second pallet each include a porous material that is conductive and has an average pore size of 0.05 μm to 20 μm. <4> A method for manufacturing a battery according to any one of <1> to <3>, wherein the porous material is porous carbon with a porosity of 0.5% to 50%. <5> The method for manufacturing a battery according to any one of <1> to <4>, wherein the step of obtaining the first electrode laminate includes forming a current collector foil on a surface of a first film fixed to a first pallet, and then applying a first electrode material to the surface of the current collector foil to form a first electrode layer; and the step of obtaining the second electrode laminate includes forming a current collector foil on a surface of a second film fixed to a second pallet, and then applying a second electrode material to the surface of the current collector foil to form a second electrode layer.<6> The method for manufacturing a battery according to any one of <1> to <5>, wherein the step of obtaining a first electrode laminate includes collectively applying a first electrode material to current collector foils fixed to a plurality of first pallets, and the step of obtaining a second electrode laminate includes collectively applying a second electrode material to current collector foils fixed to a plurality of second pallets. <7> The method for manufacturing a battery according to any one of <1> to <6>, wherein the first electrode material or the second electrode material is an electrode material for a quasi-solid battery containing an electrode active material and an electrolyte, respectively. <8> A pallet connected to a suction device and fixing at least components constituting a battery by suction, the pallet comprising a conductive porous material having an average pore size of 0.05 μm to 20 μm. <9> The pallet according to <8>, wherein the porous material is porous carbon having a porosity of 0.5% to 50%.

[0008] According to an embodiment of the present disclosure, there is provided a battery manufacturing method for efficiently manufacturing high-performance batteries (e.g., quasi-solid-state batteries). According to another embodiment of the present disclosure, there is provided a pallet for use in battery manufacturing for efficiently manufacturing high-performance batteries (e.g., quasi-solid-state batteries).

[0009] FIG. 1 is a schematic cross-sectional view illustrating the fixation of a positive electrode laminate by a first pallet. FIG. 2 is a schematic cross-sectional view illustrating the fixation of a negative electrode laminate by a second pallet. FIG. 3 is an explanatory diagram illustrating the arrangement of multiple first pallets for batch coating of positive electrode material. FIG. 4 is an explanatory diagram illustrating batch coating of positive electrode material on multiple first pallets. FIG. 5(A) is an explanatory diagram illustrating embedding a first film into the gap between two first pallets. FIG. 5(B) is an explanatory diagram illustrating batch coating of current collecting foil and positive electrode material on multiple first pallets with embedded first films. FIG. 6 is an explanatory diagram illustrating first pallets separated after batch coating of current collecting foil and positive electrode material. FIG. 7(A) is an explanatory diagram illustrating the first pallet that fixes the first film and positive electrode laminate. FIG. 7(B) is an explanatory diagram illustrating the second pallet that fixes the second film and negative electrode laminate. FIG. 8 is an explanatory diagram illustrating the suction mechanism of the first pallet. FIG. 9 is an explanatory diagram illustrating the arrangement of positive electrode layer 14 and negative electrode layer 24 in predetermined positions facing each other with separator 31 interposed therebetween. Fig. 10 is an explanatory diagram illustrating the formation of a battery stack in which the positive electrode layer and the negative electrode layer are bonded together by suction of the second pallet. Fig. 11 is an explanatory diagram illustrating the heat fusion of the films.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. 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. Components indicated by the same reference numerals in the drawings are the same components. Descriptions of duplicated components and reference numerals in the drawings may be omitted. The dimensional ratios in the drawings do not necessarily represent the actual dimensional ratios.

[0011] In the present disclosure, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the upper and lower limits. In the numerical ranges described in stages in the present disclosure, the upper or lower limit described in a certain numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit described in a certain numerical range may be replaced with a value shown in the examples. In the present disclosure, the term "step" includes not only an independent step, but also a step that cannot be clearly distinguished from other steps, as long as the intended purpose of the step is achieved. In the present disclosure, when multiple substances corresponding to each component are present in the composition, the amount of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, a combination of two or more preferred embodiments or forms is a more preferred embodiment or form. In the present disclosure, a "solid component" means a component that is solid at 25°C and 1 atmosphere, and a "liquid component" means a component that is liquid at 25°C and 1 atmosphere. In the present disclosure, compounds that are not specified as substituted or unsubstituted may have any substituent within the scope that does not impair the effects of the present disclosure. In the present disclosure, a combination of preferred embodiments is a more preferred embodiment.

[0012] When embodiments of the present disclosure are described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each drawing are conceptual, and the relative size relationships between the components are not limited to these.

[0013] <Method for manufacturing battery> The method for manufacturing a battery disclosed herein is a method for manufacturing a battery including a first electrode layer, a separator, and a second electrode layer, and includes the steps of: obtaining a first electrode laminate by forming the first electrode layer on the surface of a first film; obtaining a second electrode laminate by forming a second electrode layer on the surface of a second film; and arranging the first electrode laminate fixed to a first pallet by fixing the first film with a first pallet having a fixing function, and the second electrode laminate fixed to a second pallet by fixing the second film with a second pallet having a fixing function, in predetermined positions where the first electrode layer and the second electrode layer face each other via the separator. a step of releasing the first film from the first pallet while continuing to fix it to the second pallet, and fixing both the second film and the first film to the second pallet, thereby forming a battery stack on the second pallet in which the second electrode stack, separator, and first electrode stack are stacked in this order; and a step of heat-sealing the first film and the second film at an end of the battery stack fixed to the second pallet, wherein the area of ​​the first film is larger than that of the first electrode layer, the area of ​​the second film is larger than that of the second electrode layer, and the area of ​​the first film is larger than that of the second film.

[0014] The background to the embodiments of the present disclosure will be described. For example, in a method for manufacturing a quasi-solid battery using quasi-solid electrodes, quasi-solid electrodes formed on positive and negative current collector foils are bonded to the separators interposed therebetween. However, if the positional accuracy of the positive and negative quasi-solid electrodes during bonding is poor, this can lead to short circuits or performance degradation. That is, even if the positive and negative quasi-solid electrodes are efficiently manufactured by appropriately forming a coating film that will become the quasi-solid electrode on a transport pallet (hereinafter referred to as the pallet) and shaping it into a rectangular shape of the desired size when manufacturing the positive and negative electrodes, if the positional accuracy of bonding the positive and negative quasi-solid electrodes is poor, a highly accurate quasi-solid battery may not be formed.

[0015] In manufacturing batteries such as quasi-solid-state batteries, the present inventors have focused on utilizing the pallet used in forming the electrodes during bonding in order to improve the positional accuracy of bonding the positive and negative electrodes without reducing production efficiency, and have completed an embodiment of the present disclosure that can improve the positional accuracy of bonding the positive and negative electrodes while integrating the processes from forming the positive and negative electrodes to bonding them, and even the heat welding of the laminated cell.

[0016] According to the battery manufacturing method of the present disclosure, when bonding a positive electrode including a current collector foil and an electrode and a negative electrode including a current collector foil and an electrode via a separator, the positive electrode and negative electrode, each fixed to two pallets, are transferred to one pallet without misalignment, and a battery stack including the positive electrode, negative electrode, and separator is fixed to the pallet as a whole. This prevents misalignment between the components constituting the battery, including the positive electrode and negative electrode, when bonding the positive electrode and negative electrode together. Furthermore, because the battery stack can be laminated and packaged with a film while fixed to the pallet, a laminated cell can be produced with minimized misalignment between components such as the positive electrode and negative electrode, even during heat fusion, which is prone to misalignment. Furthermore, these processes can be performed on one electrode without removing it from the pallet on which the electrode is formed, resulting in high efficiency. Therefore, the battery manufacturing method of the present disclosure allows for efficient production of high-performance batteries (preferably quasi-solid-state batteries). The term "pallet" includes both the first and second pallets.

[0017] Furthermore, when a film having an electrode layer formed thereon is transported alone, flapping of the film can cause the end of the electrode layer to collapse, resulting in poor production. By using the transport pallet of the present disclosure, in addition to improving the positional accuracy of lamination, it is possible to suppress poor production, such as the end of the electrode layer collapsing due to flapping of the film, when a film having an electrode layer formed thereon is transported alone.

[0018] (Step of Obtaining First Electrode Laminate and Second Electrode Laminate) The battery manufacturing method of the present disclosure includes a step of obtaining a first electrode laminate by forming a first electrode layer on the surface of a first film, and a step of obtaining a second electrode laminate by forming a second electrode layer on the surface of a second film. The first electrode in the first electrode layer, first electrode laminate, etc. is a positive electrode or a negative electrode. Similarly, the second electrode in the second electrode layer, second electrode laminate, etc. is a positive electrode or a negative electrode. When the first electrode is a positive electrode, the second electrode is a negative electrode, and when the first electrode is a negative electrode, the second electrode is a positive electrode. Below, as an example, a case where the first electrode is a positive electrode and the second electrode is a negative electrode will be mainly described, but a case where the first electrode is a negative electrode and the second electrode is a positive electrode can also be described in a similar manner.

[0019] The process of obtaining a positive electrode laminate as a first electrode laminate includes forming a positive electrode layer on a surface of a first film, and the process of obtaining a negative electrode laminate as a second electrode laminate includes forming a negative electrode layer on a surface of a second film. The positive electrode layer includes a current collecting foil and a positive electrode material, and the negative electrode layer includes a current collecting foil and a negative electrode material.

[0020] First Film or Second Film: The first film or second film is a film on whose surface a positive electrode layer or a negative electrode layer can be formed. In a later process, the edges of these films are heat-sealed to fix a battery stack including a positive electrode stack and a negative electrode stack, thereby forming a laminate cell. Therefore, the first film or second film is preferably a heat-sealable laminate film, and a laminate film conventionally used as a pouch for laminate cells can be used. The laminate film is preferably a resin film made of a resin, and examples of the resin film include polyethylene terephthalate (PET) film, polypropylene (PP) film, polyethylene (PE) film, cyclic olefin polymer (COP, COC) film, triacetyl cellulose (TAC) film, polyimide (PI) film, and polyamide (PA) film. The first film or second film may be a single type of resin film or a laminate of multiple types of resin films.

[0021] The first film and the second film satisfy the following conditions: the area of ​​the first film is larger than that of the positive electrode layer, the area of ​​the second film is larger than that of the negative electrode layer, and the area of ​​the first film is larger than that of the second film. Because the first film and the second film are laminate films that form a pouch, the areas of the first film and the second film are large enough to hold the positive electrode layer, negative electrode layer, etc. inside and package the product by heat sealing. Furthermore, because the area of ​​the first film is larger than that of the second film, a second pallet can fix both the second film and the first film in a later process.

[0022] Current Collector Foil The current collector foil includes a current collector foil used for a conventionally known positive electrode current collector or negative electrode current collector. Examples of the positive electrode current collector include aluminum, aluminum alloy, stainless steel, nickel, and titanium. The positive electrode current collector is preferably aluminum or an aluminum alloy. The positive electrode current collector may be aluminum having a coating layer on its surface that contains one or more of carbon, nickel, titanium, silver, gold, platinum, and vanadium oxide.

[0023] Examples of the negative electrode current collector include aluminum, copper, a copper alloy, stainless steel, nickel, and titanium. The negative electrode current collector is preferably aluminum, copper, a copper alloy, or stainless steel, and more preferably copper or a copper alloy. The negative electrode current collector may be copper or stainless steel having a coating layer on its surface containing one or more of carbon, nickel, titanium, silver, and lithium.

[0024] The current collector foil is preferably an aluminum foil (including an aluminum foil having the above-described coating layer on its surface) or a copper foil (including a copper foil having the above-described coating layer on its surface). Aluminum foil is usually used as a positive electrode current collector. Copper foil is usually used as a negative electrode current collector.

[0025] Forming a positive electrode layer on one surface of the first film or forming a negative electrode layer on one surface of the second film can be performed by a conventionally known method. For example, a current collector foil can be formed on one surface of the first film, and a positive electrode material containing a positive electrode active material and a conductive additive can be applied to the surface of the current collector foil to form a positive electrode laminate including the current collector foil and the positive electrode material. Similarly, a current collector foil can be formed on one surface of the second film, and a negative electrode material containing a negative electrode active material and a conductive additive can be applied to the surface of the current collector foil to form a negative electrode laminate including the current collector foil and the negative electrode material. Note that a film on which a current collector foil has already been formed can also be used as the first film or the second film.

[0026] In the steps of obtaining a positive electrode laminate and a negative electrode laminate, it is preferable that the step of obtaining the positive electrode laminate includes forming a current collector foil on the surface of a first film fixed to a first pallet, and then applying a positive electrode material to the surface of the current collector foil to form a positive electrode layer, and the step of obtaining the negative electrode laminate includes forming a current collector foil on the surface of a second film fixed to a second pallet, and then applying a negative electrode material to the surface of the current collector foil to form a negative electrode layer.

[0027] The positive electrode material or the negative electrode material may be a conventionally known material that can be applied. For example, a positive electrode material or a negative electrode material for a quasi-solid battery or an all-solid battery may be used. A conventionally known method may also be used as the application method. An appropriate application method may be selected depending on the material to be applied, etc.

[0028] When a positive electrode layer or a negative electrode layer is formed by applying a positive electrode material or a negative electrode material to the surface of a current collector foil, the positive electrode material or the negative electrode material is preferably an electrode material for a quasi-solid-state battery containing the respective electrode active material and electrolyte. Note that the electrode material includes both a positive electrode material and a negative electrode material.

[0029] -Electrode Material- Each component of the electrode material for the quasi-solid-state battery will be described. The electrode material contains at least an electrode active material, a conductive additive, and an electrolyte solution, and may contain other components as necessary.

[0030] (Electrode active material) The 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.

[0031] (Positive Electrode Active Material) The positive electrode active material is not limited, and any known electrode active material used for positive electrodes can be used. The positive electrode active material is preferably a positive electrode active material that can reversibly insert and release lithium ions.

[0032] 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.

[0033] 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).

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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).

[0038] 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:

[0039] 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)).

[0040] 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).

[0041] Examples of lithium-containing transition metal silicate compounds include Li ２ FeSiO ４ , Li ２ MnSiO ４ , and Li ２ CoSiO ４ Examples include:

[0042] 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:

[0043] 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.

[0044] 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.

[0045] 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 0.1 μm (preferably 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 50 μm (preferably 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.

[0046] 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.

[0047] 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, known milling methods may be used to adjust the particle size of the positive electrode active material.

[0048] 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.

[0049] The content of the positive electrode active material relative to the total volume of the electrode material is preferably 30% by volume to 60% by volume, more preferably 35% by volume to 55% by volume, and even more preferably 40% by volume to 50% by volume. In the battery manufacturing method according to the present disclosure, it is preferable to determine the amount of the positive electrode active material used so that the content in the electrode layer falls within the above-mentioned range.

[0050] (Negative electrode active material) The negative electrode active material is not limited, and any known 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] The metal oxide and metal composite oxide are particularly preferably amorphous oxides.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] The negative electrode active material is available, for example, as CGB20 (Nippon Graphite Industries Co., Ltd.).

[0060] The composition of the negative electrode active material is measured using inductively coupled plasma (ICP) emission spectroscopy.

[0061] 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.

[0062] 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.

[0063] The particle size of the negative electrode active material can be adjusted, for example, by using a pulverizer or a classifier.

[0064] 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.

[0065] The content of the negative electrode active material relative to the total volume of the electrode material is preferably 30% by volume to 60% by volume, more preferably 35% by volume to 57% by volume, and even more preferably 45% by volume to 55% by volume. In the method for producing an electrode layer according to the present disclosure, the amount of the negative electrode active material used is preferably determined so that the content in the electrode layer falls within the above-mentioned range.

[0066] 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.

[0067] (Conductive additive) 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.

[0068] 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).

[0069] 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 an electrode layer 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.

[0070] (Electrolyte) The electrode material contains an electrolyte. The electrolyte is not particularly limited, and a known electrolyte can be used. For example, the electrolyte contains an electrolyte and a solvent. For example, a specific electrolyte contains a lithium salt compound as an electrolyte and a carbonate compound as a solvent.

[0071] 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.

[0072] 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.

[0073] As the electrolyte contained in the electrolytic solution, for example, a known inorganic solid electrolyte can be used.

[0074] 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.

[0075] 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 preferably, for example, 30% by volume to 50% by volume.

[0076] (Solvent) 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 solution. 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] (Other Components) In addition to the above components, the electrode material may contain inorganic solid electrolytes, binders, dispersants, other additives, etc. From the viewpoint of improving energy density, the electrode material preferably has a low binder (also referred to as resin component) content, preferably 1 mass % or less, and particularly preferably no binder (0 mass %). In addition to the resin component, the binder includes components called rheology modifiers and dispersants, such as 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. Known additives added to electrodes can be used as other additives.

[0081] (Preparation of Electrode Material) The electrode material can be prepared by, for example, mixing an electrode active material, a conductive additive, and an electrolytic solution, and, if necessary, an inorganic solid electrolyte and other components. Examples of the mixing method include methods using a ball mill, a bead mill, a planetary mixer, a blade mixer, a roll mill, a kneader, or a disk mill.

[0082] The battery manufacturing method of the present disclosure is a method for manufacturing batteries with high productivity and high efficiency using fewer steps than conventional methods, and is therefore a manufacturing method particularly suitable for use when the electrode material is an electrode material for a quasi-solid battery, because the quasi-solid electrode can be formed by coating, which further enhances the advantages of quasi-solid batteries, such as fewer steps and excellent LCA.

[0083] The formation of the positive electrode layer or the negative electrode layer is preferably carried out on the first pallet or the second pallet, respectively. Since the subsequent processes are also carried out using the first pallet or the second pallet, the entire process from the application of the positive electrode material or the negative electrode material to the subsequent production of the laminated cell can be carried out using the first pallet or the second pallet. This leads to improved productivity in battery production.

[0084] As shown in FIG. 1 , the first film 11 is fixed to the first pallet 15 by a fixing function of the first pallet 15, thereby forming a positive electrode laminate 10. The positive electrode laminate 10 formed on the surface of the first film 11 is also fixed to the first pallet 15 by fixing the first film 11 to the first pallet 15. The positive electrode laminate 10 is a laminate in which the first film 11, a current collector foil 12, and a positive electrode material 13 are stacked in this order. The positive electrode layer 14 includes the current collector foil 12 and the positive electrode material 13. As shown in FIG. 2 , the second film 21 is fixed to the second pallet 25 by a fixing function of the second pallet 25, thereby forming a negative electrode laminate 20. The negative electrode laminate 20 formed on the surface of the second film 21 is also fixed to the second pallet 25 by fixing the second film 21 to the second pallet 25. The negative electrode laminate 20 is a laminate in which a second film 21, a current collector foil 22, and a negative electrode material 23 are laminated in this order. The negative electrode layer 24 includes the current collector foil 22 and the negative electrode material 23. Note that Fig. 1 is a schematic cross-sectional view of the positive electrode laminate 10 taken along line II shown in Fig. 6.

[0085] In the process of obtaining the positive electrode laminate 10 and the negative electrode laminate 20, it is preferable that the process of obtaining the positive electrode laminate 10 includes applying a positive electrode material 13 to the current collector foils 12 fixed to the plurality of first pallets 15 in a lump, and the process of obtaining the negative electrode laminate 29 includes applying a negative electrode material 23 to the current collector foils 22 fixed to the plurality of second pallets 25 in a lump.

[0086] This allows the application of the positive electrode material 13 or the negative electrode material 23 to a plurality of pallets at once in the application process of the positive electrode material 13 or the negative electrode material 23, resulting in high efficiency.

[0087] In addition, in the case of both the positive electrode material 13 and the negative electrode material 23, when the electrode materials are applied in a lump, it is preferable to adjust the area of ​​the film by embedding the film between a plurality of pallets, etc. This makes it possible to efficiently make the area of ​​the film suitable for thermal fusion.

[0088] The following method can be used to adjust the area of ​​the film, for example. As shown in FIG. 3 , multiple pallets 15 are arranged with their long sides touching, and long films 11 are placed on them. At this time, the film is embedded in the gap between the pallets to a predetermined length on the long side where the two pallets touch. Thereafter, current collector foils 12 are formed on the multiple first films 11 all at once. Next, as shown in FIG. 4 , positive electrode material 13 is applied to the films all at once. This forms a positive electrode layer 14. Note that embedding the film in the gap between the pallets can be done as shown in FIG. 5(A). The area of ​​the first films 11 can be adjusted by adjusting the embedding length. Thereafter, current collector foils 12 and positive electrode material 13 are formed all at once, as shown in FIG. 5(B).

[0089] Next, the multiple pallets that were in contact with each other are separated. As a result, the collectively coated positive electrode material 13 or negative electrode material 23 is separated for each pallet. Next, as shown in FIG. 6 , the film is cut away to form the positive electrode material 13 on each pallet. The negative electrode layer 24 can also be formed in the same manner as the positive electrode layer 14. Therefore, the area of ​​the first film 11 can be formed larger than that of the positive electrode layer 14, and the area of ​​the second film 21 can be formed larger than that of the negative electrode layer 24.

[0090] In this way, by embedding the film in the gaps between pallets arranged side by side, the electrode material can be applied all at once, allowing the area of ​​the first film 11 to be larger than that of the positive electrode layer 14, and the area of ​​the second film 21 to be larger than that of the negative electrode layer 25. As shown in FIG. 7(A), a positive electrode laminate 10 is formed in which the area of ​​the first film 11 is adjusted, and as shown in FIG. 7(B), a negative electrode laminate 20 is formed in which the area of ​​the second film 21 is adjusted. Note that when the electrode material is applied all at once, tabs or the like for extracting power may be formed in advance on the current collecting foil. In this case, a rectangular pallet can be used, but the shape of the pallet is not limited as long as the film can be embedded.

[0091] Furthermore, regarding the area of ​​the films used in the first pallet 15 on which the positive electrode laminate 10 is formed and the second pallet 25 on which the negative electrode laminate 20 is formed, by using a first film 11 that is larger than the second film 21 to be fixed to the first pallet 15 in advance, the area of ​​the first film 11 can be made larger than the area of ​​the second film 21 efficiently.

[0092] By making the area of ​​the first film 11 larger than that of the positive electrode layer 14 and the area of ​​the second film 21 larger than that of the negative electrode layer 24, regions of each film, such as the ends where no electrode layer is formed, can be used as fusion regions to fuse the first film 11 and the second film 21. Note that ends where no electrode layer is formed can also be formed on the short sides of the pallet, and fusion can be performed on all four sides of the pallet to form a sealed laminate cell. Note that, because the area of ​​the first film 11 is larger than that of the second film, the positive electrode layer 14 and the negative electrode layer 24 can be bonded, heat-fused, and the like, without any misalignment, as will be described later.

[0093] (Step of placing the first electrode laminate and the second electrode laminate in a predetermined position) The manufacturing method of the battery according to the present disclosure includes a step of placing the positive electrode laminate 10 fixed to the first film 11 by a first pallet 15 having a fixing function, and the negative electrode laminate 20 fixed to the second film 21 by a second pallet having a fixing function, in a predetermined position such that the positive electrode layer 14 and the negative electrode layer 24 face each other with the separator interposed therebetween.

[0094] The fixing function of the first pallet 15 or the second pallet 25 is a function of fixing the first film 11 or the second film 21, thereby fixing the positive electrode laminate 10 or the negative electrode laminate 20 formed on the first film 11 or the second film 21, respectively. Note that the fixing function not only fixes an object to be fixed, but also includes a function of releasing the fixation of the fixed object. For example, by releasing the fixation of the first pallet, etc., the fixed first film 11, etc. can be released and made free to move.

[0095] The first pallet 15 has a function of releasing the fixation of the first film 11 in addition to a function of fixing the first film 11, because in a later process, by releasing the fixation of the first film 11, the first film 11 and the positive electrode laminate 10 formed on the first film 11 are delivered so as to be superimposed on the negative electrode laminate 20 via the separator. Furthermore, the second pallet 25 forms a battery stack including the positive electrode laminate 10, the separator, the negative electrode laminate 20, etc. by fixing the first film 11 and the second film 21 in a later process, so the fixing function of the second pallet 25 is a function that enables the battery stack to be formed on the second pallet 25 by fixing the first film 11 and the second film 21. The fixing function can be selected from a plurality of functions that enable the first film 11 and / or the second film 21 to be fixed.

[0096] The fixing function may be a physical fixing function. For example, a gripping mechanism may be provided on each of the first pallet 15 and the second pallet 25, and the first film 11 and / or the second film 21 may be gripped by the gripping mechanism to fix or release the fixation. Alternatively, the fixing function may be a suction function. A suction function is preferable as the suction function. For example, the suction function may fix the first film 11 and / or the second film 21 by vacuum suction, and release the fixation by stopping the vacuum suction, etc.

[0097] The fixing function is preferably a suction function, and fixing is performed by suction. When the fixing function is a suction function, it is possible to control the strength and speed of suction, and thus the degree of fixation. Furthermore, damage to the fixed object can be reduced compared to physical fixation. Therefore, by using a suction function as the fixing function, the fixed object can be held on the pallet while preventing breakage, physical damage, etc. Furthermore, the pallet can be moved at high speed while the fixed object is fixed. For example, the positive electrode layer 14 and the negative electrode layer 24 can be aligned at high speed, and there is little risk of damaging the fixed object when transferring the positive electrode layer 14 to the second pallet 25. Furthermore, by controlling the degree of fixation, fixing and release can be performed quickly. Furthermore, compared to physical fixation, the equipment can be simplified.

[0098] The suction device that realizes the suction function may be any device capable of fixing the first film 11 and / or the second film 21 to the pallet by vacuum suction. For example, a device including a plurality of holes formed on the surface of each of the first pallet 15 and the second pallet 25, where the object to be fixed is fixed by suction, may be used. In this case, each of the first pallet 15 and the second pallet 25 is provided with an air intake pipe, and air is drawn through the air intake pipe to reduce the pressure inside the holes of the pallet, thereby suctioning and fixing the first film 11 and / or the second film 21 arranged in the surface area of ​​the first pallet 15 and the second pallet 25 where the holes are formed. The pallet may have a plurality of holes formed on its surface and be capable of reducing the pressure inside the holes. For example, the pallet may be made of a porous material. Pallets made of porous material will be described later.

[0099] As shown in Figure 8, the suction device is composed of, for example, a plurality of holes 101 formed in the surface of the first pallet 15 and an air intake pipe 102 connected to the first pallet 15 and a vacuum pump (not shown). The suction function of the suction device is to suck air from within the holes 101 formed in the surface of the first pallet 15 through the air intake pipe 102, thereby reducing the pressure inside the holes 101 and thereby holding and fixing the first film 11 on the surface of the first pallet 15. The suction device of the second pallet 25 is similar to that of the first pallet 15, and is composed of a plurality of holes 201 formed in the surface of the second pallet 25 and an air intake pipe 202 connected to the second pallet 25 and a vacuum pump (not shown). The suction device sucks air from within the holes 201 formed in the surface of the second pallet 25 through the air intake pipe 202, thereby reducing the pressure inside the holes 201 and thereby holding and fixing the first film 11 and / or second film 21 on the surface of the second pallet 25.

[0100] The suction device preferably has a suction control function that controls the degree of fixation by controlling the strength and speed of suction. The suction control function can control the strength of fixation of the first film 11 and / or the second film 25, the degree and speed of release when the fixation is released, etc. Specifically, the suction device may be connected to a pallet and reduce the pressure to control the degree of fixation between the pallet and the film. The fixation strength is controlled by the degree of pressure reduction, and the speed of fixation and break (release) is controlled by controlling the time it takes to reach the desired pressure. The means for achieving reduced pressure in the suction device can be a common device, such as a diaphragm type, rotary vane type, or oil rotary type. Common valves and regulators can be used as control methods. Their operation can also be electronically controlled. For example, in the case of the first pallet 15, the suction control function may be a function that stops suction from the intake pipe 102 to transition the reduced pressure inside the hole 101 to atmospheric pressure and release the first film 11. Alternatively, the suction control function may be a function that stops suction from the intake pipe 102 to maintain the reduced pressure inside the hole 101 and maintain the fixation of the first film 11, and when the fixation of the first film 11 is released, exhaust the air from the intake pipe 102 while adjusting the degree of pressure so as to quickly transition the reduced pressure to atmospheric pressure. Alternatively, the suction control function may be a function that adjusts the pressure to atmospheric pressure, or a function that allows gas to flow in at a pressure greater than atmospheric pressure. The suction control function in the second pallet 25 is the same as that in the case of the first pallet 15 described above.

[0101] As a method for arranging the positive electrode laminate 10 fixed to the first pallet 15 and the negative electrode laminate 20 fixed to the second pallet 25 at predetermined positions where the positive electrode layer 14 and the negative electrode layer 24 face each other via the separator, the arrangement direction, method, etc. are not important as long as they can be arranged at the predetermined positions. The predetermined position is a position where at least the positive electrode layer 14 and the negative electrode layer 24 can be bonded together in a later process with reduced misalignment as components that constitute a battery, and is preferably a position where they can be bonded together with higher precision.

[0102] The predetermined position where the positive electrode layer 14 and the negative electrode layer 24 face each other with the separator interposed therebetween can be, for example, a position where the positive electrode layer 14 and the negative electrode layer 24 face each other in the vertical direction. Specifically, the first pallet 15 to which the positive electrode laminate 10 is fixed is adjusted in an orientation such that the first pallet 15 and the positive electrode laminate 10 are arranged in this order from above, and is then placed above the second pallet 25 to which the negative electrode laminate 20 is fixed so as to face each other with the separator 31 interposed therebetween, thereby allowing the positive electrode laminate 10 and the negative electrode laminate 20 to be placed at predetermined positions where the positive electrode layer 14 and the negative electrode layer 24 face each other. When the positive electrode layer 14 or the negative electrode layer 24 is placed at predetermined positions following the step of forming the positive electrode layer 14 or the negative electrode layer 24 by coating, this can be achieved by not adjusting the position of the second pallet 25 to which one negative electrode laminate 20 is fixed, but by vertically inverting only the first pallet 15 to which the other positive electrode laminate 10 is fixed and placing it above the second pallet 25. Therefore, the process of manufacturing the positive electrode layer 14 or the negative electrode layer 24 and the process of arranging the positive electrode layer 14 or the negative electrode layer 24 can be performed consistently with fewer steps, resulting in high efficiency. Note that each process in the battery manufacturing method of the present disclosure can be performed while the first pallet 15 and the second pallet 25 are being transported. Because the pallets can appropriately fix the objects to be fixed, the process of manufacturing the positive electrode layer 14 or the negative electrode layer 24, the process of arranging the positive electrode layer 14 or the negative electrode layer 24, etc. can be appropriately performed while the pallets are being transported.

[0103] In order to bond the positive electrode layer 14 and the negative electrode layer 24 more accurately, a device for determining the position of the positive electrode layer 14 or the negative electrode layer 25 may be used. For example, the position of the positive electrode layer 14 or the negative electrode layer 24 may be acquired as an image, the positions of the positive electrode layer 14 and the negative electrode layer 24 may be determined by image processing, and the position information may be used to determine a predetermined position where the positive electrode layer 14 and the negative electrode layer 24 face each other with the separator interposed therebetween.

[0104] The separator can be appropriately selected from those conventionally used in quasi-solid-state batteries, and examples thereof include porous films containing resin materials such as polyethylene, polypropylene, polybutene, polyvinyl chloride, polyethylene terephthalate, polyethersulfone, polyamide, polyimide, polyimideamide, polyaramid, polycycloolefin, nylon, and polytetrafluoroethylene.

[0105] As shown in FIG. 9 , the first pallet 15 to which the positive electrode laminate 10 is fixed is inverted vertically and placed above the second pallet 25, whereby the positive electrode layer 14 and the negative electrode layer 24 are arranged in predetermined positions facing each other with the separator 31 interposed therebetween.

[0106] (Step of forming battery stack on second pallet) The battery manufacturing method of the present disclosure includes a step of forming a battery stack on the second pallet 25, in which the positive electrode stack 10, the separator 31, and the negative electrode stack 20 are stacked in this order, by releasing the fixation by the first pallet 15 while continuing the fixation by the second pallet 25, and fixing both the second film 21 and the first film 11 to the second pallet 25.

[0107] Because the positive electrode laminate 10 and the negative electrode laminate 20 are arranged at predetermined positions facing each other with the separator 31 interposed therebetween, by releasing the fixation of the positive electrode laminate 10 by the first pallet 15 while continuing to fix the negative electrode laminate 20 by the second pallet 25, the positive electrode laminate 10 becomes free from fixation by the first pallet 15. Meanwhile, the second pallet 25 continues to fix the negative electrode laminate 20 and fixes the first film 11 to fix the positive electrode laminate 10. Therefore, the second pallet 25 fixes the negative electrode laminate 20, the separator 31, and the positive electrode laminate 10 together. Note that the negative electrode laminate 20, the separator 31, and the positive electrode laminate 10 stacked in this order constitute a battery stack. In the present disclosure, the area of ​​the first film 11 is larger than the area of ​​the second film 21, and therefore the first film 11 can be fixed in an area of ​​the second pallet 25 where the second film 21 is not fixed.

[0108] When the fastening function is a suction function, controlling the suction can control the fastening of the first film 11, allowing for more reliable integration without damaging the battery stack. Therefore, misalignment, which is prone to occur when laminating the positive electrode layer 14 and the negative electrode layer 24, can be effectively suppressed while preventing damage. For example, during heat fusion, the first pallet 15 with the positive electrode layer 14 fixed thereto and the second pallet 25 with the negative electrode layer 24 fixed thereto can be pressed against each other across the separator 31, and then the peripheral films can be heat fused. However, because the battery stack including the positive electrode layer 14, the separator 31, and the negative electrode layer 24 is not restricted in movement, the pressure from the heat fusion plate during heat fusion may cause misalignment of the layers. In the battery manufacturing method disclosed herein, the first film 11 is fixed to the second pallet 25, thereby restricting movement of the battery stack. Therefore, even if the battery stack is pressed against the heat-sealing plate during heat sealing, the first film 11 restricts movement of the battery stack, making it difficult for the layers of the battery stack to shift.

[0109] After the positive electrode layers 14 and negative electrode layers 24 are arranged in predetermined positions facing each other with the separator 31 interposed therebetween, the suction of the first pallet 15 is released while the suction of the second pallet 25 is continued. As a result, as shown in Figure 10 , the first film 11 that was fixed by the first pallet 15 is sucked onto the second pallet 25 and fixed to the second pallet 25. This forms a battery stack 32 in which the positive electrode layers 14 and negative electrode layers 24 are bonded together with the separator 31 interposed between them. The fixing function of the second pallet 25 fixes the first film 11 and the second film 21 together, and the battery stack 32 is fixed to the second pallet 25 in a state where it is covered by the first film 11.

[0110] (Step of heat-sealing the first film and the second film) The battery manufacturing method of the present disclosure includes a step of heat-sealing the first film 11 and the second film 21 at the end of the battery stack 32 fixed to the second pallet 25. The heat-sealing method can be a conventional method, in which the portions of the first film 11 and the second film 21 to be heat-sealed are heated and compressed.

[0111] In the battery manufacturing method disclosed herein, the first film 11 and the second film 21 are fixed by the second pallet 25. Therefore, when the first film 11 and the second film 21 are heat-sealed to each other, the first film 11 and the second film 21, which are the objects to be welded, are less likely to shift, making heat welding more reliable. Furthermore, as described above, even if the battery stack 32 is pressed against it by a heat-seal plate during heat sealing, the movement of the battery stack 32 is limited by the first film 11, so the layers of the battery stack 32 are less likely to shift.

[0112] As shown in Figure 11 , the first film 11 and the second film 21 are fixed together by the fastening function of the second pallet 25, and with the battery stack 32 fixed to the second pallet 25, the first film 11 and the second film 21 are heat-sealed together using a heat-sealing device. The arrows in Figure 11 indicate the locations where heat welding is performed. This laminate-packages the battery stack 32, forming a laminated cell containing the components that make up the battery.

[0113] Preferably, the first pallet 15 and the second pallet 25 each comprise a porous material that is conductive and has an average pore size of 0.05 μm to 20 μm. Examples of conductive porous materials include porous metal and porous carbon. By using a conductive pallet, for example, when the battery is manufactured in a dry room, the pallet is less likely to become charged and static electricity can be prevented, preventing adverse effects on the batteries during manufacture.

[0114] It is preferable that each pallet securely fasten the first film 11 or the second film 21. However, if the fastening function of the first pallet and the second pallet 25 is a suction function, for example, if the pallets are perforated, air may leak through the holes in areas where no objects are present, requiring a relatively strong suction force to more reliably fasten the objects by suction, which may not be economically efficient. If the pallet is made of a porous material, the pores of the porous material have a relatively small diameter and little air leakage, making it less likely for air to leak through the holes in areas where no objects are present. Therefore, when each pallet secures an object by suction, a relatively strong suction force is not required, resulting in excellent economic efficiency.

[0115] The porous material is preferably porous carbon with a porosity of 0.5% to 50%. Because the porous material is porous carbon, the pore size is relatively small, resulting in little air leakage, while the number of pores is very large, resulting in relatively strong suction force and rapid release of the fixation. A porous material with a porosity of 0.5% to 50% is preferred because it can more reliably prevent air leakage while more reliably fixing and releasing the first film 11 or the second film 21. More preferably, the porosity of the porous material is 10% to 40%. In the present disclosure, the porosity of the porous material is a value measured by methods such as mercury intrusion porosimetry, Archimedes' method, SEM and image analysis of the cut surface, etc. Porous materials are described further below.

[0116] <Pallet> The pallet of the present disclosure is connected to a suction device and fixes at least the components that make up a battery by suction, and comprises a porous material that is conductive and has an average pore size of 0.05 μm to 20 μm.

[0117] The inventors focused on the material of the pallet used in battery manufacturing, and by using a pallet made of a specific material, they completed an embodiment of the present disclosure in which at least the components that make up the battery are properly fixed by suction.

[0118] According to the pallet of the present disclosure, by using a pallet containing a specific material, it is possible to appropriately fix a film or the like. Therefore, for example, it is possible to bond a positive electrode and a negative electrode fixed to the pallet with high precision without misalignment. Furthermore, by adjusting the suction force, the fixation can be adjusted according to the object to be fixed, and the fixation can be quickly released as desired. Therefore, by using the pallet of the present disclosure, it is possible to efficiently manufacture a quasi-solid-state battery with excellent performance.

[0119] The pallet of the present disclosure is, for example, a first pallet 15 or a second pallet 25 (see FIGS. 1 and 2 ), which are connected to a vacuum pump or the like via a suction pipe or the like and fix the first film 11 or the second film 21, which are components that make up the battery, by suction. The pallet of the present disclosure can be used, for example, as the first pallet 15 or the second pallet 25 for manufacturing positive electrodes or negative electrodes, and can also be used to fix entire laminate cells in which positive electrodes and negative electrodes are bonded together with a separator interposed therebetween, or to fix batteries in which the ends of laminate cells are heat-sealed. Specifically, the pallet of the present disclosure is similar to the first pallet 15 or the second pallet 25 described above.

[0120] The pallet of the present disclosure comprises a porous material, such as porous metal, porous carbon, porous ceramic (silicon carbide), porous graphite, and the like.

[0121] The average pore size of the porous material is preferably 0.05 μm to 20 μm, and more preferably 0.4 μm to 10 μm. When the average pore size is within the range of 0.05 μm to 20 μm, the pallet fixes the object to be fixed by suction, so a relatively strong suction force is not required, resulting in excellent economic efficiency. The average pore size of the porous material is a value measured by methods such as mercury intrusion porosimetry, Archimedes' method, SEM and image analysis of the cut surface, etc.

[0122] The porous material is preferably porous carbon with a porosity of 0.5% to 50%. When the porous material is porous carbon, the pore size is relatively small, resulting in little air leakage, while the number of pores is very large, resulting in relatively strong suction force and rapid release of the fixation. A porosity of 0.5% to 50% is preferable because it allows the first film 11 or the second film 21 to be fixed and released more reliably while more reliably suppressing air leakage. A porosity of 0.5% to 50% is more preferable.

[0123] The porous carbon provided in the pallet can be a commercially available material, such as "Porous Carbon" (manufactured by Tanken Seal Seiko Co., Ltd., porosity 35%).

[0124] Furthermore, depending on the manufacturing equipment, if the pallet's fixing function is a suction function, the suction capacity is set appropriately depending on the size of the pallet and the size of the electrode to be produced. Excessive exhaust equipment is not necessary for the size of the manufacturing equipment. By combining a vacuum pump with a set suction capacity with the porous material, it is possible to more appropriately fix the object to be fixed using the pallet, adjust the fixation, and release the fixation.

[0125] The pallet of the present disclosure can be used continuously from the initial stage of battery production to the completion of the battery because it can appropriately secure battery components by suction during battery production. For example, on each of the two pallets for manufacturing positive and negative electrodes, a laminate film on which a current collector foil is formed can be first secured by suction, and subsequent processes can be performed continuously while the battery components are secured to the pallet. The pallet can secure by suction the object to be secured, in which battery components such as current collector foil, electrode layer, and tabs for extracting electricity are wrapped in a laminate film, and then heat-seal the film to form a laminate cell. The formed laminate cell can also be transported while secured to the pallet.

[0126] As described above, the pallet of the present disclosure includes a specific porous material, allowing at least battery components to be appropriately fixed and released by suction. Therefore, by using the pallet of the present disclosure, for example, positive and negative electrodes can be bonded while being fixed, thereby enabling high-precision bonding of the electrodes. Furthermore, for example, the battery manufacturing process, from the formation of electrode layers to the production of laminated cells, can be performed in an integrated manner. Furthermore, the pallet of the present disclosure allows for accurate bonding of positive and negative electrode layers, making it a pallet used in a manufacturing method for efficiently producing high-performance quasi-solid-state batteries. Furthermore, when a film having an electrode layer formed thereon is transported alone, flapping of the film can sometimes cause a production degradation, such as the collapse of the electrode layer end portion. However, by using the transport pallet of the present disclosure, in addition to improving the positional accuracy of the lamination, it is possible to suppress a production degradation, such as the collapse of the electrode layer end portion due to flapping of the film when the film having an electrode layer formed thereon is transported alone. Although the above description has mainly focused on quasi-solid-state batteries, the battery manufacturing method and pallet of the present disclosure can also be applied to all-solid-state batteries and the like.

[0127] The above embodiment will be specifically described below using examples, but the above embodiment is not limited to these examples.

[0128] (Preparation of Positive Electrode Material) (1) A mixture of ethylene carbonate, propylene carbonate, and diethyl carbonate was added with 0.9 mol / L of LiPF ６ After mixing the solution (electrolyte), vinylene carbonate (VC) was further mixed to obtain electrolytic solution X1. (2) 2 g of a conductive additive (Ketjen black) and 174 g of a positive electrode active material (lithium iron phosphate) were stirred for 30 seconds at 1500 rpm (revolutions per minute) in a mixer (Thinky Mixer ARE-310, manufactured by Thinky Corporation) to prepare kneaded material Y1 (176 g). (3) 64 g of electrolytic solution X1 was added to the kneaded material Y1 (176 g), and the mixture was stirred for 120 seconds at 1500 rpm in a Thinky Mixer (manufactured by Thinky Corporation) to obtain a positive electrode composition (solid content: 48% by volume), which is a positive electrode material.

[0129] (Preparation of Negative Electrode Material) (1) Electrolyte solution X1 (64 g) was prepared, which was the same as that used in the preparation of the positive electrode composition. (2) 6.5 g of the conductive additive and 152.5 g of graphite, the negative electrode active material, were stirred for 18 seconds at 900 rpm in a mixer (Thinky Corporation) to prepare a kneaded material Z1. (3) Electrolyte solution X1 (64 g) was added to the kneaded material Z1 (159 g), and the mixture was stirred for 30 seconds at 900 rpm in a mixer (Thinky Corporation) to obtain a negative electrode composition (solid content: 52% by volume), which was the negative electrode material.

[0130] Example 1: 30 mm thick porous carbon pallets ("Porous Carbon" manufactured by Tanken Seal Seiko Co., Ltd., porosity 35%) were prepared as the first and second pallets. Each of the first and second pallets had a plurality of holes on its surface and was equipped with a suction device consisting of an intake pipe connected to a vacuum pump at the bottom of the pallet. Each of the first and second pallets was capable of being transported or moved by a transport device, and the following steps were performed while the first and second pallets were being transported.

[0131] A polyethylene terephthalate (PET) film (first film) 12 μm thick, 550 mm long, and 155 mm short was placed on the surface of the first pallet, and the air inside the holes in the first pallet was sucked out using an air intake pipe to reduce the pressure inside the holes and hold the first PET film in place.A polyethylene terephthalate (PET) film (second film) 12 μm thick, 500 mm long, and 150 mm short was placed on the surface of the second pallet, and the air inside the holes in the second pallet was sucked out using an air intake pipe to reduce the pressure inside the holes and hold the second PET film in place.

[0132] While the second PET film was still attached to the second pallet, an adhesive was applied to the surface of the second PET film attached to the surface of the second pallet and dried to form an 8 μm thick adhesive layer. An aluminum foil (positive electrode current collector foil, thickness 20 μm, surface roughness Ra 0.5 μm, carbon coating) was then laminated on the surface of the adhesive layer. The positive electrode current collector foil had a current collector foil body and a tab portion for extracting electricity.

[0133] The positive electrode composition was applied to the surface of the current collector foil to form a positive electrode layer with a thickness of 297.3 μm, thereby obtaining a positive electrode laminate.

[0134] While the first PET film was still held on the first pallet, an adhesive was applied to the surface of the first PET film provided on the surface of the first pallet and dried to form an adhesive layer with a thickness of 8 μm. Copper foil (negative electrode current collector foil, thickness 10 μm, surface roughness Ra 0.55 μm current collector foil body) and a tab portion for extracting electricity were laminated on the surface of the adhesive layer.

[0135] The negative electrode composition was applied to the surface of the negative electrode current collector foil to form a negative electrode layer with a thickness of 320.0 μm, thereby obtaining a negative electrode laminate.

[0136] A polyethylene separator (thickness: 20 μm) was prepared as the separator. The separator was laminated on the surface of the negative electrode stack, with the ends of the separator held by holding members (made of aluminum).

[0137] The positive electrode laminate having the second PET film and the positive electrode layer formed on the second PET film was inverted vertically while held on the second pallet and placed vertically above the first pallet, with the positive electrode layer 14 and the negative electrode layer 24 facing each other and positioned appropriately when laminated together with the separator interposed therebetween. Note that the first pallet continued to hold the first PET film and the negative electrode laminate formed on the first PET film.

[0138] When the suction of the first pallet was continued and the suction of the second pallet was released, the edge of the second PET film was held by the first pallet. As a result, a battery stack consisting of an adhesive layer, a positive electrode current collector foil, a positive electrode layer, a separator, a negative electrode layer, a negative electrode current collector foil, and an adhesive layer was provided in the space formed by the second PET film and the first PET film. Furthermore, because the area of ​​the first PET film held by the first pallet at the edge of each of the four sides was larger than that of the second PET film held by the second pallet, the first pallet sucked the PET film into the second PET film, thereby holding the battery stack without misalignment.

[0139] While continuing to suction the first pallet, heat sealing was performed on the edges of the four overlapping sides of the first PET film and the second PET film, and after the sealing was completed, the formed laminated cell-shaped battery was removed from the first pallet. The battery included, in this order, the first PET film, a current collecting foil for the electrode, a positive electrode layer, a separator, a negative electrode layer, a current collecting foil for the negative electrode, an adhesive layer, and the second PET film.

[0140] The manufactured batteries were visually observed. Specifically, the batteries held on the second pallet were visually observed from above to check for protrusion of the positive electrode layer from the positive electrode current collector foil and the negative electrode layer from the negative electrode current collector. If protrusion was confirmed, it was determined that the positive electrode layer and the negative electrode layer had collapsed. However, no collapse of the positive electrode layer and the negative electrode layer was confirmed. In addition, the distance (A1) between the corner of the positive electrode layer of the battery and the corner of the tab portion of the positive electrode current collector foil was determined, and the absolute value (|A1 - A0|) of the difference from the planned distance between the corners (A0: 132.4 mm) was calculated. It was found to be less than 0.2 mm, indicating that the batteries had been bonded without any misalignment.

[0141] The disclosure of Japanese Patent Application No. 2024-033399, filed on March 5, 2024, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A method for manufacturing a battery comprising a first electrode layer, a separator, and a second electrode layer, comprising the steps of: forming the first electrode layer on the surface of a first film to obtain a first electrode laminate; forming the second electrode layer on the surface of a second film to obtain a second electrode laminate; arranging the first electrode laminate, which is fixed to a first pallet by a first pallet having a fixing function fixing the first film, and the second electrode laminate, which is fixed to a second pallet by a second pallet having a fixing function fixing the second film, in predetermined positions where the first electrode layer and the second electrode layer face each other via the separator; releasing the fixation by the first pallet while continuing to fix the second film and the first film to the second pallet, thereby forming a battery laminate on the second pallet in which the second electrode laminate, the separator, and the first electrode laminate are stacked in this order; and heat-sealing the first film and the second film at an end of the battery laminate fixed to the second pallet. A method for manufacturing a battery, wherein the area of ​​the first film is larger than that of the first electrode layer, the area of ​​the second film is larger than that of the second electrode layer, and the area of ​​the first film is larger than that of the second film.

2. The method for manufacturing a battery according to claim 1, wherein the fixing function is a suction function, and the fixing is performed by suction.

3. The method for manufacturing a battery according to claim 1, wherein the first pallet and the second pallet each comprise a porous material that is conductive and has an average pore size of 0.05 μm to 20 μm.

4. The method for manufacturing a battery according to claim 3, wherein the porous material is porous carbon having a porosity of 0.5% to 50%.

5. A method for manufacturing a battery as described in claim 1, wherein the step of obtaining the first electrode laminate includes forming a current collecting foil on the surface of the first film fixed to the first pallet, and then applying a first electrode material to the surface of the current collecting foil to form the first electrode layer, and the step of obtaining the second electrode laminate includes forming a current collecting foil on the surface of the second film fixed to the second pallet, and then applying a second electrode material to the surface of the current collecting foil to form the second electrode layer.

6. A method for manufacturing a battery as described in claim 5, wherein the step of obtaining the first electrode laminate includes collectively applying the first electrode material to the current collecting foils fixed to the plurality of first pallets, and the step of obtaining the second electrode laminate includes collectively applying the second electrode material to the current collecting foils fixed to the plurality of second pallets.

7. The method for manufacturing a battery according to claim 5, wherein the first electrode material or the second electrode material is an electrode material for a quasi-solid battery containing an electrode active material and an electrolyte solution, respectively.

8. A pallet that is connected to a suction device and fixes at least the components that make up a battery by suction, the pallet being made of a conductive porous material with an average pore size of 0.05 μm to 20 μm.

9. A pallet according to claim 8, wherein the porous material is porous carbon having a porosity of 0.5% to 50%.