Method for manufacturing molded body for sheet electrode

Abstract

A method for producing a molded body for a sheet-shaped electrode, the method including: a first step of preparing particles containing an electrode active material and / or a conductive auxiliary agent; and a second step for obtaining a mixture of an electrode active material, a conductive auxiliary agent, and an electrolyte solution using the particles prepared in the first step, and forming an electrode material film containing the electrode active material, the conductive auxiliary agent, and the electrolyte solution on a support.

Description

Technical Field

[0001] The present invention relates to a method for producing a formed body for a sheet-like electrode. Background Art

[0002] In recent years, the development of semi-solid-state batteries has been explored.

[0003] The electrode used for the semi-solid battery is produced using, for example, an electrode material containing at least a powdered electrode active material and an electrolyte.

[0004] For example, Japanese Patent Application Laid-Open No. 2020-129448 discloses a method for producing a battery electrode, which includes a deposition step of depositing a powder including granulated particles containing an electrode active material and a conductive additive on a surface of a current collector. Summary of the invention

[0005] Technical issues to be solved by the invention

[0006] As an electrode used in a semi-solid battery, it is preferable to apply a technique for improving energy density by using a sheet-like electrode molded body containing a solid component such as an electrode active material at a higher concentration than an electrolyte.

[0007] As a method for obtaining a sheet-shaped electrode formed body containing solid components such as electrode active materials at high concentrations, for example, there is a method of forming an electrode material containing solid components such as electrode active materials at high concentrations compared to an electrolyte into a sheet on a support. However, the electrolyte containing the electrode material of the solid component at high concentration is small, so the adhesion (adhesion) to the support is small, and if a sheet-shaped body is obtained on the support, it may sometimes cause the end to collapse.

[0008] Here, the collapse of the edge of the sheet-like electrode molded body includes both the case where the edge of the sheet-like electrode molded body, which is an aggregate of the electrode material, collapses slightly and the case where the edge peels off in a large plate shape, and can be confirmed by a CCD camera or the like.

[0009] Therefore, the present invention has been completed in view of the above circumstances.

[0010] An object of one embodiment of the present invention is to provide a method for producing a sheet-like electrode molded body capable of producing a sheet-like electrode molded body having a high solid content concentration with good moldability.

[0011] Here, "good formability" means that the sheet-shaped electrode molded body can be formed into a desired shape without causing collapse or chipping at the end.

[0012] Means for solving technical problems

[0013] The present invention includes the following aspects.

[0014] <1> A method for producing a sheet-shaped electrode molded body, comprising:

[0015] In the first step, particles containing one or both of an electrode active material and a conductive auxiliary agent are prepared; and

[0016] In the second step, the particles prepared in the first step are used to obtain a mixture of an electrode active material, a conductive auxiliary agent and an electrolyte solution.

[0017] Then, an electrode material film including an electrode active material, a conductive auxiliary agent, and an electrolyte solution is formed on the support.

[0018] <2> The method for producing a sheet-shaped electrode molded body according to <1>, wherein:

[0019] The first step includes a granulation step of granulating one or both of the electrode active material and the conductive auxiliary agent.

[0020] <3> The method for producing a sheet-shaped electrode molded body according to <2>, wherein:

[0021] The maximum filling rate of the granules obtained in the granulation step is 55 volume % to 95 volume %.

[0022] <4> The method for producing a sheet-shaped electrode molded body according to <2> or <3>, wherein:

[0023] The granulation step is a step of combining the electrode active material and the conductive auxiliary agent and granulating them.

[0024] <5> The method for producing a sheet-shaped electrode molded body according to <4>, wherein:

[0025] The volume average particle size of particles obtained by combining the electrode active material and the conductive auxiliary agent and granulating them is 10 μm to 1000 μm.

[0026] <6> The method for producing a sheet-shaped electrode molded body according to <2> or <3>, wherein:

[0027] The granulation step is a step of granulating one of the electrode active material and the conductive auxiliary agent, or granulating both the electrode active material and the conductive auxiliary agent.

[0028] <7> The method for producing a sheet-shaped electrode molded body according to <6>, wherein:

[0029] The volume average particle size of particles obtained by granulating the electrode active material is 10 μm to 1000 μm.

[0030] <8> The method for producing a sheet-shaped electrode molded body according to <6>, wherein:

[0031] The volume average particle size of the particles obtained by granulating the conductive auxiliary agent is 0.2 μm to 50 μm.

[0032] <9> The method for producing a sheet-shaped electrode molded body according to <2>, wherein:

[0033] The granulation was carried out by dry granulation.

[0034] <10> The method for producing a sheet-shaped electrode molded body according to <2>, wherein:

[0035] Granulation is performed by a wet granulation method using at least a part of the electrolyte.

[0036] <11> The method for producing a sheet-shaped electrode molded body according to any one of <1> to <10>, wherein:

[0037] The mixture obtained in the second step is applied to a support to form an electrode material film containing an electrode active material, a conductive auxiliary agent, and an electrolyte solution on the support.

[0038] <12> The method for producing a sheet-like electrode molded body according to any one of <1> to <10>, wherein:

[0039] The second step is a step of providing the particles prepared in the first step onto a support to obtain a mixture of an electrode active material, a conductive auxiliary agent, and an electrolyte solution on the support.

[0040] <13> The method for producing a sheet-like electrode molded body according to any one of <1> to <12>, comprising the step of applying pressure or vibration to a mixture of an electrode active material, a conductive additive, and an electrolyte solution disposed on a support.

[0041] <14> The method for producing a sheet-like electrode molded body according to any one of <1> to <13>, wherein:

[0042] The electrode material film has a thickness of 70 μm to 230 μm and a solid content concentration of 50 volume % to 80 volume %.

[0043] Effects of the Invention

[0044] According to one embodiment of the present invention, it is possible to provide a method for producing a sheet-like electrode molded body capable of producing a sheet-like electrode molded body having a high solid content concentration with good moldability. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic cross-sectional view for explaining a first embodiment of the method for producing a molded body for an electrode according to the present invention.

[0046] Figure 2 It is a schematic cross-sectional view for explaining a second embodiment of the method for producing a molded body for an electrode according to the present invention.

[0047] Figure 3 It is a schematic cross-sectional view for explaining the step of pressurizing the electrode material film.

[0048] Figure 4 This is a schematic diagram showing an image inspection device for evaluating the moldability of a sheet-shaped electrode molded body (electrode material film). DETAILED DESCRIPTION

[0049] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The present invention is not limited to the following embodiments and can be implemented with appropriate changes within the scope of the purpose of the present invention. Constituent elements represented by the same symbols in the drawings refer to the same constituent elements. The description of the constituent elements and symbols repeated in the drawings may sometimes be omitted. The ratio of the dimensions in the drawings does not necessarily represent the ratio of the actual dimensions.

[0050] In the present invention, the numerical range represented by "to" refers to a range including the numerical values ​​recorded before and after "to" as the lower limit and the upper limit. In the numerical range recorded in stages in the present invention, the upper limit or lower limit recorded in a certain numerical range can be replaced by the upper limit or lower limit of the numerical range recorded in other stages. In addition, in the numerical range recorded in the present invention, the upper limit or lower limit recorded in a certain numerical range can be replaced by the value shown in the embodiment.

[0051] In the present invention, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process can be achieved.

[0052] In the present invention, "(meth)acrylic acid" means both or either one of acrylic acid and methacrylic acid.

[0053] In the present invention, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition refers to the total amount of the plurality of substances present in the composition unless otherwise specified.

[0054] In the present invention, a combination of two or more preferred aspects or configurations is a more preferred aspect or configuration.

[0055] In the present invention, the "solid content" refers to a component that is solid at 25°C and 1 atmosphere, and the "liquid content" refers to a component that is liquid at 25°C and 1 atmosphere.

[0056] <Method for producing a molded body for sheet-shaped electrode>

[0057] The method for manufacturing a sheet electrode forming body involved in the present invention includes: a first step of preparing particles containing one or both of an electrode active material and a conductive auxiliary agent; and a second step of using the particles prepared in the first step to obtain a mixture of the electrode active material, the conductive auxiliary agent and the electrolyte, and forming an electrode material film containing the electrode active material, the conductive auxiliary agent and the electrolyte on a support.

[0058] Hereinafter, the "sheet-shaped molded body for electrode" is also simply referred to as "molded body for electrode".

[0059] In the present invention, "granules" refer to a substance obtained by solidifying a plurality of powders (powders) with air between the powders and molding them into particles larger than the powders. That is, the granules have voids formed by air between the powders.

[0060] In addition, forming into particles larger than powder is called "granulation".

[0061] In the present invention, the electrode material film preferably has a thickness of 70 μm to 230 μm and a solid content concentration of 50 volume % to 80 volume %. That is, the method for producing an electrode molded body according to the present invention preferably forms an electrode material film having a thickness of 70 μm to 230 μm and a solid content concentration of 50 volume % to 80 volume %.

[0062] In the present invention, “high solid content concentration” means that the solid content concentration is 50% by volume or more.

[0063] Here, the thickness of the electrode material film is set to the arithmetic mean of thicknesses at three locations measured by cross-sectional observation. A known microscope (for example, a scanning electron microscope) can be used for cross-sectional observation.

[0064] The solid content concentration of the electrode material film is calculated based on the composition ratio of each component included in the electrode material film and the specific gravity of these components.

[0065] As described above, when a sheet-shaped electrode molded body is formed on a support using an electrode material containing a high concentration of solid components, it is difficult to obtain an electrode material film of a desired shape because the electrode material has a low adhesion (adhesion force) to the support and the end portions collapse.

[0066] Therefore, the inventors have found a method for obtaining a sheet-shaped electrode molded body with good formability by using a method for granulating a powder material. By making the electrode active material or the conductive auxiliary agent as a powder into particles, the surface area can be reduced compared to before they become particles. The electrode active material or the conductive auxiliary agent has the power to maintain the electrolyte on its surface, so if it becomes particles and the surface area is reduced, the amount of electrolyte in the electrolyte in the electrode material that is not maintained by particles and has a fluid state increases. As a result, it is inferred that if the electrode active material or the conductive auxiliary agent that becomes particles is included, even if the electrode material containing solid components at a high concentration, the adhesion to the support body is also shown. As a result, a sheet-shaped electrode molded body can be formed with good formability.

[0067] Japanese Patent Application Publication No. 2020-129448 discloses the use of a powder containing granulated particles containing an electrode active material and a conductive auxiliary agent. However, Japanese Patent Application Publication No. 2020-129448 does not mention the use of such granulated particles to obtain a mixture of an electrode active material, a conductive auxiliary agent, and an electrolyte.

[0068] [1st step]

[0069] In the first step, particles containing one or both of an electrode active material and a conductive auxiliary agent are prepared.

[0070] In the present invention, "preparing particles" means making the particles ready for use, and includes preparing particles unless otherwise specified. That is, in the first step, previously prepared particles or commercially available particles may be obtained, or particles may be prepared.

[0071] Examples of the particles prepared in this step include particles of an electrode active material, particles of a conductive auxiliary agent, and particles containing both an electrode active material and a conductive auxiliary agent (hereinafter also referred to as combined particles).

[0072] [Pelletization process]

[0073] The first step preferably includes a granulation step of granulating one or both of the electrode active material and the conductive auxiliary agent to obtain particles.

[0074] As a method for granulating one or both of the electrode active material and the conductive auxiliary agent, there is no particular restriction as long as it is a method that can granulate one or both of the electrode active material and the conductive auxiliary agent, and dry granulation or wet granulation can be used. In addition, when using the wet granulation method, from the viewpoint that the particles obtained by granulation can be directly used in the first step, as a liquid component, at least a part of the electrolyte is preferably used.

[0075] Specifically, the granulation may be performed by a dry granulation method or a wet granulation method using at least a part of the electrolyte solution.

[0076] In addition, the electrode active material or the conductive auxiliary agent is preferably subjected to a dispersion treatment before being applied to the dry granulation method or the wet granulation method.

[0077] In the granulation process, granules are mainly obtained (for example, 95% by volume or more), but sometimes a part of raw materials that have not become granules (electrode active materials and conductive additives in the form of powders) remain. In the case where granules and raw materials that have not become granules are mixed in the particle group obtained after granulation, the raw materials that have not become granules can be removed by a sieve or the like.

[0078] In particular, when obtaining composite particles, in addition to the target particles containing both the electrode active material and the conductive auxiliary agent, particles not containing either the electrode active material or the conductive auxiliary agent or raw materials that have not become particles are sometimes included. In this case, the raw materials that have not become particles can also be removed as needed.

[0079] As the apparatus used for the dry granulation method, for example, there can be mentioned dry granulation apparatuses such as the dry granulator (roller press FT, etc.) of FREUND-TURBO CORPORATION and the dry granulator (tablet press (Chilsonator)) of POWREX Corporation. In addition, as the apparatus used for the dry granulation method, a well-known roll mixer can also be used.

[0080] As an apparatus used for the dry granulation method, an apparatus using a mechanochemical method may be used. By using an apparatus using a mechanochemical method, granules can be obtained and a smoothing treatment of the powder surface can be performed.

[0081] As an apparatus used for the wet granulation method, a wet granulation apparatus such as a fluidized bed granulation dryer (FD-MP-01 etc.) of Powrex Corporation is mentioned, for example.

[0082] As the liquid component used in the wet granulation method, at least a part of the electrolyte solution is preferably used. Specifically, as the liquid component used in the wet granulation method, a material that is solid at room temperature (eg, 25° C.) such as ethylene carbonate (ethylene carbonate) can be cited.

[0083] In addition, when a material that is solid at room temperature, such as ethylene carbonate, is used as a liquid component, the solid material can be made into a liquid by passing through a nozzle heated (to a temperature above the melting point, such as 60° C.), and then put into a wet granulation device. The material that is solid at room temperature put into the wet granulation device splashes from the nozzle, adheres to the electrode active material and / or the conductive auxiliary agent in the device, and solidifies to become a part of the particles.

[0084] From the perspective of maintaining the particle state and facilitating particle disintegration due to mixing with the electrolyte, the maximum filling rate of the particles obtained in the granulation step is preferably 55% to 95% by volume, more preferably 60% to 90% by volume, and further preferably 65% ​​to 85% by volume.

[0085] The maximum filling rate of the particles can be calculated from the particle size of the particles, the particle size of the powder contained in the particles, and the distribution thereof.

[0086] The granulation step is preferably a step of combining the electrode active material and the conductive auxiliary agent and granulating them. Through this step, the above-mentioned combined particles can be obtained.

[0087] Here, "combining and granulating the electrode active material and the conductive auxiliary agent" means using both the electrode active material and the conductive auxiliary agent as raw materials and granulating the materials. In the granulation, the above-mentioned dry granulation method or wet granulation method is applied. Thus, combined particles, that is, particles containing both the electrode active material and the conductive auxiliary agent, can be obtained.

[0088] In order to efficiently obtain composite particles, it is preferred to mix and disperse the electrode active material and the conductive additive before applying the dry granulation method or the wet granulation method. To mix and disperse the electrode active material and the conductive additive, a known mixing and dispersing mechanism can be used.

[0089] The volume average particle size of the combined particles, i.e., particles obtained by combining and granulating the electrode active material and the conductive aid, is preferably 10 to 1000 μm, more preferably 25 to 500 μm, further preferably 50 to 300 μm, and particularly preferably 150 to 250 μm.

[0090] The granulation step is also preferably a step of granulating one of the electrode active material and the conductive auxiliary agent, or a step of granulating both the electrode active material and the conductive auxiliary agent.

[0091] The volume average particle size of particles obtained by granulating the electrode active material is preferably 10 μm to 1000 μm, more preferably 25 μm to 500 μm, and even more preferably 50 μm to 300 μm.

[0092] The volume average particle size of the particles obtained by granulating the conductive auxiliary agent is preferably 0.2 μm to 50 μm, more preferably 10 μm to 50 μm, and even more preferably 20 μm to 50 μm.

[0093] Here, the volume average particle size of the particles can be measured by a dry particle size measurement method, for example, a method using a laser diffraction / scattering particle size distribution analyzer.

[0094] In addition, the details of the electrode active material, the conductive auxiliary agent, the electrolyte solution, etc. used in this step and the second step will be described later.

[0095] [Second step]

[0096] In the second step, the particles prepared in the first step are used to obtain a mixture of an electrode active material, a conductive auxiliary agent, and an electrolyte solution.

[0097] The mixture obtained in this process is obtained by mixing the particles prepared in the first process and the components other than the particles. The components other than the particles refer to the components other than the components introduced as particles in the components used to obtain the mixture of the electrode active material, the conductive auxiliary agent and the electrolyte. For example, if the particles prepared in the first process are particles of the electrode active material, the components other than the particles are at least the conductive auxiliary agent and the electrolyte, and additives may be included as needed. And, for example, if the particles prepared in the first process are combined particles of the electrode active material and the conductive auxiliary agent, the components other than the particles are at least the electrolyte, and additives may be included as needed.

[0098] In addition, as a component other than particles, at least one of an electrode active material that is not in a granular form and a conductive auxiliary agent that is not in a granular form may be contained.

[0099] In the method for manufacturing an electrode formed body involved in the present invention, by imparting the mixture of electrode active material, conductive aid and electrolyte obtained in this process to a support, or performing this process of obtaining a mixture of electrode active material, conductive aid and electrolyte on a support, an electrode material film containing electrode active material, conductive aid and electrolyte can be formed on the support.

[0100] That is, as a first embodiment of the method for producing an electrode molded body according to the present invention, there is mentioned an embodiment in which the mixture obtained in this step is applied to a support to form an electrode material film containing an electrode active material, a conductive auxiliary agent and an electrolyte solution on the support.

[0101] In addition, as a second embodiment of the method for producing the electrode molded body involved in the present invention, the following embodiment can be cited: This step is a step of imparting the particles prepared in the first step to a support, and obtaining a mixture of an electrode active material, a conductive additive and an electrolyte solution on the support.

[0102] [First method]

[0103] The above-mentioned first aspect will be described.

[0104] In the first mode, a mixture to be applied to a support is prepared, and the prepared mixture is applied to the support.

[0105] As a method for preparing the mixture to be applied to the support, any mixing mechanism can be used without limitation as long as it is a mixing mechanism capable of mixing the particles prepared in the first step and components other than the particles.

[0106] As the mixing mechanism, for example, a ball mill, a bead mill, a planetary mixer, a blade mixer, a roll mill, a kneader, or a disk mill can be used.

[0107] The mechanism for applying the mixture obtained as described above to the support may be any mechanism as long as it can apply a desired amount of the mixture to the support.

[0108] As a mechanism for applying the mixture to the support, for example, a mechanism for intermittently or continuously supplying the mixture to the support (for example, a hopper, a screw feeder, a disk feeder, a vibrating feeder, etc.) can be used.

[0109] Furthermore, when the mixture is applied to the support, a limiting frame or a grid frame may be used from the viewpoint of uniformly applying the mixture.

[0110] [Second method]

[0111] The second aspect described above will be described.

[0112] In the second aspect, in the second step, the particles prepared in the first step are provided on a support to obtain a mixture of an electrode active material, a conductive auxiliary agent, and an electrolyte solution on the support.

[0113] Specifically, in the second embodiment, the particles prepared in the first step and components other than the particles are separately provided on the support. Thus, the particles and components other than the particles are mixed on the support to obtain a mixture of an electrode active material, a conductive additive, and an electrolyte solution.

[0114] When components other than particles are provided on the support, if there are two or more components other than particles (for example, a conductive auxiliary agent and an electrolyte solution), they may be provided on the support separately or as a mixed mixture.

[0115] Furthermore, when the particles prepared in the first step and components other than the particles are separately applied to the support, it is preferred that the components other than the particles including the electrolyte are first applied to the support, and then the particles prepared in the first step are applied thereon. By setting this order, it is easy to obtain the adhesion of the electrolyte to the support, and an electrode material film can be formed with good formability.

[0116] As the mechanism for providing the particles prepared in the first step to the support, the same mechanism as the mechanism for providing the mixture to the support in the first embodiment can be used.

[0117] Furthermore, as a mechanism for imparting components other than particles to the support, it is only necessary to appropriately select according to the type of components other than particles. As a mechanism for imparting components other than particles to the support, specifically, in addition to the mechanism for imparting the mixture to the support in the first mode, various coating mechanisms (for example, coating mechanisms using slit coating, rod coating, blade coating, etc.) can be used.

[0118] According to the first or second embodiment, a mixture of an electrode active material, a conductive aid and an electrolyte is arranged on a support. From the viewpoint of easily disintegrating particles, making the mixing of the components more uniform, and forming an electrode material film with uniform concentration distribution of the components, it is preferred to apply pressure or vibration to the mixture of the electrode active material, the conductive aid and the electrolyte arranged on the support.

[0119] That is, the method for producing an electrode molded body according to the present invention preferably includes a step of applying pressure or vibration to a mixture of an electrode active material, a conductive auxiliary agent, and an electrolyte solution disposed on a support.

[0120] As a method of applying pressure to the mixture on the support, a method of applying pressure from the upper part of the mixture toward the support may be used.

[0121] As a method of applying pressure to the mixture, specifically, a method of pressing the mixture from the top toward the support by a pressing member can be enumerated. At this time, from the viewpoint of suppressing the volatilization of the liquid component, it is preferred to place a film on the mixture and utilize the pressing member to press the mixture from the film.

[0122] Examples of the pressing member include plate-shaped members such as scrapers and blades, rollers, flat plate presses, and roller presses.

[0123] As described above, the mixture on the support is pressed by the pressing member. At this time, the mixture is pressed by the pressing member until the mixture obtained after pressing, that is, the electrode material film has a thickness of the above-mentioned thickness: 70 μm to 230 μm.

[0124] As a method of applying vibration to the mixture on the support, any method of applying vibration to the mixture may be used.

[0125] Specifically, the method of applying vibration to the mixture may be a method of applying vibration to the mixture by bringing a vibrating member into contact with the mixture from above, or a method of applying vibration to the mixture by vibrating a support on which the mixture is placed.

[0126] As the vibrating member, the same member as the above-mentioned pressing member is used. By vibrating the pressing member, vibration can be applied to the mixture in contact with the vibrating pressing member.

[0127] In particular, from the viewpoint of forming an electrode material film with uniform thickness and uniform concentration distribution of each component, it is preferred to apply pressure and vibration to the mixture on the support. Specifically, it is preferred to press the mixture on the support toward the support from the upper part thereof by a vibrating pressing member.

[0128] There is no particular limitation on the vibration direction of the pressing member when vibrating the pressing member. Furthermore, the vibration of the pressing member may be continuous or intermittent.

[0129] The amplitude of the vibration of the pressing member is, for example, preferably 0.1 μm to 60 μm, and more preferably 1 μm to 10 μm.

[0130] Furthermore, the frequency of the vibration of the pressing member is, for example, preferably 50 Hz to 40,000 Hz, and more preferably 100 Hz to 37,500 Hz. In addition, the frequency of the vibration of the pressing member may include multiple frequencies. For example, the vibration of the pressing member may be a vibration in which multiple frequency peaks such as 150 Hz, 300 Hz, and 450 Hz are detected.

[0131] Here, the amplitude and frequency of the vibration can be measured by an acceleration sensor or a vibration measuring device. In addition, when measuring the vibration of the pressing component, when multiple frequency peaks are detected, the frequency of the minimum value is set as the "frequency of the vibration of the pressing component", and the amplitude at this frequency is set as the "amplitude of the vibration of the molding material". For example, with respect to the vibration of the pressing component, when multiple frequency peaks such as 150 Hz, 300 Hz and 450 Hz are detected, 150 Hz is set as the "frequency of the vibration of the pressing component", and the amplitude at the frequency of 150 Hz is set as the "amplitude of the vibration of the pressing component".

[0132] Below, reference Figure 1 and Figure 2 , an example of a method for producing a molded body for an electrode according to the present invention is described.

[0133] Figure 1 is a schematic cross-sectional view for explaining the first embodiment. Figure 2 It is a schematic cross-sectional view for explaining the second embodiment.

[0134] exist Figure 1 In the first embodiment shown, first, the mixture 22 is continuously applied from the applying mechanism 20 storing the mixture 22 containing particles to the support 10 moving in the direction of the arrow X, and a film 24 based on the mixture 22 is formed on the support 10. Next, the film 24 based on the mixture 22 formed on the support 10 is pressed using the scraper 30 as a pressing member.

[0135] To be more specific, Figure 1 As shown, the scraper 30 is arranged in such a manner that its front end contacts the film 24 and maintains a constant distance from the surface of the support 10. By moving the scraper 30 on the support 10 along the arrow X direction, the film 24 formed on the support 10 passes through the gap between the surface of the support 10 and the front end of the scraper 30, and pressure is applied to the film 24 from the scraper 30. In addition, at this time, the thickness of the film 24 can be limited to the same thickness as the above-mentioned gap. In this way, if pressure is applied to the film 24 by the scraper 30, the particles in the film 24 disintegrate, so that the electrode material film 100 containing the electrode active material, the conductive auxiliary agent and the electrolyte can be obtained.

[0136] In addition, at this time, the scraper 30 vibrates, and vibration can be applied to the film 24 .

[0137] exist Figure 2 In the second embodiment shown, first, a film 50 made of an electrolyte is formed on a support 10 moving in the direction of arrow X. Next, composite particles 42 are continuously applied to the film 50 made of the electrolyte from an application mechanism 40 storing composite particles 42, and a film 44 made of composite particles 42 is formed on the film 50. Furthermore, the film 50 and the film 44 formed on the support 10 are pressed using a scraper 30 as a pressing member.

[0138] To be more specific, Figure 2As shown, the scraper 30 is arranged in a manner that its front end contacts the film 44 and maintains a constant distance from the surface of the support 10. By moving it along the direction of arrow X on the support 10, the stack of the film 50 and the film 44 formed on the support 10 passes through the gap between the surface of the support 10 and the front end of the scraper 30, and pressure is applied to the stack. And, at this time, the thickness of the stack of the film 50 and the film 44 can be limited to the same thickness as the above-mentioned gap. In this way, if pressure is applied to the stack of the film 50 and the film 44 by the scraper 30, the particles in the film 44 disintegrate, and the film 50 and the film 44 are mixed, so that the electrode material film 100 containing the electrode active material, the conductive auxiliary agent and the electrolyte can be obtained.

[0139] In addition, in the above example, the film 50 is a film obtained from an electrolyte, but it is not limited to this mode. For example, the film 50 can be a film containing an electrolyte and at least one of an electrode active material and a conductive auxiliary agent. In this case, at least one of the electrode active material and the conductive auxiliary agent contained together with the electrolyte may be a particle or may not be a particle. In addition, the solid content concentration of the film containing at least one of an electrolyte and an electrode active material and a conductive auxiliary agent is preferably 1 volume % to 40 volume %.

[0140] Furthermore, as described above, before the step of applying pressure or vibration to the mixture containing the electrode active material, the conductive aid, and the electrolyte solution disposed on the support, the stack of the support and the mixture may be divided in the surface direction of the support.

[0141] In this method, a laminated body having a large area is formed and then divided into laminated bodies having a smaller area (for example, the area of ​​the electrodes).

[0142] Furthermore, it is preferred that pressure or vibration be applied to the mixture after the step of dividing the stacked body of the support and the mixture in the surface direction of the support.

[0143] In the above aspect, it is preferable to use a support body in which at least the surface on which the mixture is placed in advance can be divided in the surface direction.

[0144] As the above-mentioned support, for example, a plurality of metal layers (layers that become collectors) of desired sizes are separated from each other and arranged on a resin film, and the resin film portion between the metal layers is bent to the side opposite to the metal layer side so that the separated metal layers are in contact without gaps. In such a support, by dividing the metal layers in contact without gaps, the laminate of the support and the mixture can be divided in the surface direction of the support.

[0145] As described above, an electrode material film including an electrode active material, a conductive auxiliary agent, and an electrolyte solution is formed on a support.

[0146] In addition, in order to continuously form an electrode material film, that is, to form an electrode material film as a continuous film, it is preferred to use a long support body so that the long support body is transported and moved relative to a fixed particle imparting mechanism (for example, the above-mentioned imparting mechanism 40 storing the combined particles 42 or the imparting mechanism 40 storing the combined particles 42).

[0147] Here, as a mechanism for moving the support body, a known conveying mechanism can be used. Specifically, as the conveying mechanism for the support body, for example, a belt conveyor, a linear slide guide, a cross roller conveyor, etc. can be used.

[0148] In addition, the details of the support will be described later.

[0149] As described above, the electrode material film is formed on the support.

[0150] The support used here is not particularly limited as long as it is a support that can form an electrode material film on the surface. In particular, from the viewpoint of continuously forming an electrode material film, a long-sized support is preferably used. In the case of a long-sized support, its width can be determined according to the size of the electrode material film, the width of the width direction of the above-mentioned pressing member (e.g., a scraper, a roller), etc.

[0151] In addition, the details of the support will be described later.

[0152] The obtained electrode material film can be maintained as it is or can be further pressed to form a sheet-shaped electrode molded body.

[0153] 〔Other processes〕

[0154] The method for producing the electrode molded body according to the present invention may include other steps.

[0155] Examples of other steps include a step of pressing the electrode material film and a step of transferring the electrode material film formed on the release paper to the current collector when the support is release paper.

[0156] (Step of Pressurizing Electrode Material Film)

[0157] The method for producing the electrode molded body according to the present invention may include a step of pressurizing the electrode material film.

[0158] Since the method for producing an electrode molded body according to the present invention includes a pressurizing step, the density of the electrode material can be increased and the density and thickness of the solid content can be made uniform within a plane.

[0159] In this process, for example, Figure 3The method shown applies pressure to the electrode material film. Figure 3 It is a schematic cross-sectional view for explaining the step of pressurizing the electrode material film.

[0160] exist Figure 3 , after the electrode material film 100 is formed on the support 10 by pressing the film 24 with the scraper 30, a process of pressurizing the formed electrode material film 100 is shown. Figure 3 In the example shown, the film 62 is placed on the electrode material film 100 formed on the support 10, and the pressing roller 60 is pressed from above the film 62 to press the electrode material film 100. By pressing the electrode material film 100, a pressed electrode material film 102 can be obtained.

[0161] In addition, this process is not limited to Figure 3 The method shown in the figure may be a method using a pair of pressure rollers and a punch as a pressure mechanism, for example. Also, a vibrating pressure roller or a vibrating horn may be used as the pressure mechanism.

[0162] When the electrode material film is pressurized, the pressure is preferably 0.01 MPa to 100 MPa, more preferably 0.1 MPa to 50 MPa, and particularly preferably 0.2 MPa to 10 MPa.

[0163] In this step, a plurality of pressurizing mechanisms may be used to pressurize the electrode material film in stages. By using a plurality of pressurizing mechanisms to pressurize the electrode material film in stages, the density and thickness of the electrode material can be made more uniform.

[0164] In this step, it is preferred that the pressurizing mechanism and the electrode material film (specifically, the support on which the electrode material film is formed) are relatively moved.

[0165] In the present invention, "moving the pressurizing mechanism and the electrode material film relative to each other" includes moving the pressurizing mechanism in one direction relative to the electrode material film, moving the electrode material film in one direction relative to the pressurizing mechanism, and moving the pressurizing mechanism and the electrode material film in one direction respectively, but preferably moving the electrode material film in one direction relative to the pressurizing mechanism.

[0166] The mechanism for moving the electrode material film (specifically, the support body on which the electrode material film is formed) is not limited, and a known conveying mechanism can be used, for example, a belt conveyor, a linear slide guide, and a cross roller conveyor.

[0167] In this step, from the viewpoint of improving moldability, the electrode material film heated at, for example, 30° C. to 100° C. may be pressed.

[0168] Hereinafter, the support body and the pressing member used in the method for producing the electrode molded body according to the present invention will be described in detail.

[0169] Furthermore, the details of each component used to obtain an electrode material film, such as an electrode active material, a conductive auxiliary agent, and an electrolyte solution, are also described.

[0170] [Support]

[0171] As the support, specifically, a current collector is mentioned as a preferred support.

[0172] The current collector which is an example of the support is not particularly limited, and a known current collector (positive electrode current collector and negative electrode current collector) can be used.

[0173] Examples of the positive electrode current collector include aluminum, aluminum alloys, 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 containing one or more of carbon, nickel, titanium, silver, gold, platinum, and vanadium oxide on the surface.

[0174] Examples of the negative electrode current collector include aluminum, copper, copper alloys, stainless steel, nickel, and titanium. The negative electrode current collector is preferably aluminum, copper, copper alloys, or stainless steel, more preferably copper or a copper alloy. The negative electrode current collector may be copper or stainless steel having a coating layer containing one or more of carbon, nickel, titanium, silver, and lithium on the surface.

[0175] As the current collector, aluminum foil (including aluminum foil having the above-mentioned coating layer on the surface) and copper foil (including copper foil having the above-mentioned coating layer on the surface) are preferred. Usually, aluminum foil is used as the current collector in the positive electrode. Usually, copper foil is used as the current collector in the negative electrode.

[0176] Furthermore, the support may be a laminate of a metal layer and a resin film exemplified as the above-mentioned positive electrode collector or negative electrode collector. As the resin film used for the laminate, there can be cited resin films such as polyethylene terephthalate (PET) film, polypropylene (PP) film, polyethylene (PE) film, cyclic olefin polymer (COP, COC) film, triacetyl cellulose (TAC) polyimide (PI) film, and polyamide (PA) film.

[0177] Furthermore, as an example of the support, a release material can be mentioned.

[0178] Examples of the release material as an example of the support include release paper (for example, release paper manufactured by LINTEC Corporation), a film having a release layer, and paper having a release layer. Among them, release paper is preferred.

[0179] Furthermore, when a release material is used as the support, the electrode material film formed on the release material can be transferred to the current collector by utilizing the releasability of the release material.

[0180] From the viewpoint of transportability and the like, the thickness of the support (preferably a current collector) is preferably 3 μm or more, more preferably 5 μm or more, and particularly preferably 10 μm or more.

[0181] From the viewpoint of flexibility and lightness, the thickness is preferably 100 μm or less, more preferably 70 μm or less, and particularly preferably 50 μm or less.

[0182] The thickness of the support is measured by the same method as the thickness of the electrode material film.

[0183] The size of the support is not limited and may be determined according to the size of the electrode molded body to be produced, the sizes of various members used in the production process, and the like.

[0184] Furthermore, in this step, as the support body conveying mechanism, the support body conveying mechanism in the first step and the second step can be adopted.

[0185] [Pressing parts]

[0186] Preferred examples of the pressing member include a blade and a roller.

[0187] As described above, when the blade and the roller as the pressing member come into contact with the mixture, the mixture can be vibrated by using a vibrating pressing member.

[0188] (Scraper)

[0189] The scraper is a plate-like component. The shape, size, material, etc. of the contact portion that comes into contact with the mixture can be appropriately determined based on the various physical properties of the mixture (type of electrode active material, solid content concentration, composition of the electrolyte (viscosity, surface tension), etc.), the size and thickness of the electrode material film to be formed, etc.

[0190] Furthermore, it is preferred that the portion of the scraper in contact with the mixture does not easily adhere to the electrode material. For example, it is preferred that at least the surface of the scraper exhibits releasability.

[0191] For example, the scraper may be made of fluorine-based resin such as polytetrafluoroethylene (PTFE), resin such as polyetheretherketone (PEEK), metal such as stainless steel, aluminum, iron, superhard alloy, or ceramic.

[0192] Furthermore, in order to impart mold release properties to the surface, the blade may include a surface layer exhibiting mold release properties (for example, a surface layer containing a fluorine-based resin, a surface layer containing silicon-based particles and a resin).

[0193] Furthermore, from the viewpoint of improving the friction resistance, the blade may have a high hardness coating of titanium oxide, titanium nitride (TiN), tungsten carbide or the like on the metal or ceramic blade body.

[0194] (Roller)

[0195] The roller is a component whose outer peripheral surface can rotate. Its size, material, etc. can be appropriately determined according to the various physical properties of the mixture (type of electrode active material, solid content concentration, composition of the electrolyte (viscosity, surface tension), etc.), the size and thickness of the electrode material film formed, etc.

[0196] The material constituting the outer peripheral surface of the roller may be the same as that of the blade, and may have a surface layer exhibiting mold release properties.

[0197] The outer diameter of the roller is not particularly limited, but may be, for example, 20 mm to 30 mm.

[0198] Furthermore, since the roller rotates, the friction coefficient between the outer peripheral surface and the mixture can be regarded as 0. However, as a result, the adhesion to the mixture may increase, so it is preferable to insert a film between the mixture and the outer peripheral surface of the roller.

[0199] [Components constituting the electrode material film]

[0200] The electrode material film contains an electrode active material, a conductive auxiliary agent, and an electrolyte solution, and may contain additives as necessary.

[0201] (Electrode Active Material)

[0202] The electrode active material is a material that can insert and release 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.

[0203] Examples of the electrode active material include a positive electrode active material and a negative electrode active material.

[0204] -Positive electrode active material-

[0205] The positive electrode active material is not limited, and a known electrode active material used in a positive electrode can be used. The positive electrode active material is preferably a positive electrode active material that can reversibly insert and release lithium ions.

[0206] Specific examples of the positive electrode active material include transition metal oxides and elements that can be combined with lithium (eg, sulfur). Among the above, the positive electrode active material is preferably a transition metal oxide.

[0207] 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).

[0208] 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.

[0209] 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 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 substance of element Ma.

[0210] Examples of the transition metal oxide 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 halophosphate compounds, and lithium-containing transition metal silicate compounds.

[0211] Examples of transition metal oxides having a layered rock salt structure include LiCoO2 (lithium cobalt oxide [LCO]), LiNi2O2 (lithium nickel oxide), LiNi 0.85 Co 0.10 Al 0.05 O2 (nickel cobalt aluminum oxide [NCA]), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (lithium nickel manganese cobalt oxide [NMC]) and LiNi 0.5 Mn 0.5 O2 (lithium manganese nickel oxide).

[0212] Examples of transition metal oxides having a spinel structure include LiCoMnO4, Li2FeMn3O8, Li2CuMn3O8, Li2CrMn3O8, and Li2NiMn3O8.

[0213] As lithium-containing transition metal phosphate compounds, for example, there can be mentioned olivine-type iron phosphates (for example, LiFePO4 and Li3Fe2(PO4)3), pyrophosphate iron salts (for example, LiFeP2O7), cobalt phosphates (for example, LiCoPO4) and monoclinic NASICON-type vanadium phosphates (for example, Li3V2(PO4)3 (lithium vanadium phosphate)).

[0214] Examples of lithium-containing transition metal halophosphate compounds include iron fluorophosphates (eg, Li2FePO4F), manganese fluorophosphates (eg, Li2MnPO4F), and cobalt fluorophosphates (eg, Li2CoPO4F).

[0215] Examples of lithium-containing transition metal silicate compounds include Li 2 FeSiO 4 , Li 2 MnSiO 4 , and Li 2 CoSiO 4 .

[0216] The transition metal oxide is preferably a transition metal oxide having a layered rock salt structure, and more preferably selected from LiCoO2 (lithium cobalt oxide [LCO]), LiNi 0.85 Co 0.10 Al 0.05 O2 (nickel cobalt aluminum oxide [NCA]) and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 At least one compound selected from the group consisting of O2 (lithium nickel manganese cobalt oxide [NMC]).

[0217] The positive electrode active material may be a commercial product or a synthetic product produced by a known method (eg, calcination method). For example, the positive electrode active material obtained by calcination method may be washed with water, an acidic aqueous solution, an alkaline aqueous solution or an organic solvent.

[0218] Furthermore, the positive electrode active material may have a carbon coating on its surface.

[0219] The shape of the positive electrode active material is not limited, but is preferably in the form of particles from the viewpoint of handleability.

[0220] 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.

[0221] The volume average particle size of the positive electrode active material is 0.3 μm or more, thereby preventing the positive electrode active material from splashing during operation. The volume average particle size of the positive electrode active material is 40 μm or less, thereby making it easy to adjust the thickness of the electrode molded body and preventing the generation of voids during the molding process.

[0222] The volume average particle size of the positive electrode active material is measured by the following method.

[0223] 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 irradiated with 1kHz ultrasonic waves for 10 minutes is set as the measurement sample. Using a laser diffraction / scattering particle size distribution measuring device (e.g., LA-960 manufactured by HORIBA, Ltd.) and at a temperature of 25°C, 50 data readings are performed, and the volume average particle size is obtained based on the volume frequency particle size distribution.

[0224] A quartz colorimetric cell was used as the measuring cell. Five samples were used for the above measurement, and the average of the measured values ​​was defined as the volume average particle size of the positive electrode active material. For other detailed conditions, refer to "JIS Z 8828: 2013" as needed.

[0225] As a method for adjusting the particle size of the positive electrode active material, for example, a method using a pulverizer, a disintegrator, or a classifier can be cited. In addition, as a method for adjusting the particle size of the positive electrode active material, a known grinding method can be applied.

[0226] The positive electrode active material may be used alone or in combination of two or more.

[0227] Furthermore, even when a single type of positive electrode active material is used, positive electrode active materials having different particle sizes may be used in combination.

[0228] The content of the positive electrode active material relative to the total volume of the electrode material film is preferably 30% to 60% by volume, more preferably 35% to 55% by volume, and even more preferably 40% to 50% by volume.

[0229] In the method for producing an electrode molded body according to the present invention, the amount of the positive electrode active material used is determined so that the content in the electrode material film falls within the above range.

[0230] -Negative electrode active material-

[0231] The negative electrode active material is not limited, and a known electrode active material used in a negative electrode can be used. The negative electrode active material is preferably a negative electrode active material that can reversibly insert and release lithium ions.

[0232] As the negative electrode active material, for example, carbonaceous materials, metal oxides (for example, tin oxide), silicon oxide, metal combination oxides, lithium monomers, lithium alloys (for example, lithium aluminum alloys) and metals that can form alloys with lithium (for example, Sn, Si and In) can be cited. Among the above, from the viewpoint of reliability, the negative electrode active material is preferably a carbonaceous material or a lithium combination oxide.

[0233] Carbonaceous materials are materials consisting substantially of carbon.

[0234] 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 carbon fibers, cellulose carbon fibers, pitch carbon fibers, vapor-grown carbon fibers, dehydrated PVA (polyvinyl alcohol) carbon fibers, lignin carbon fibers, glassy carbon fibers, and activated carbon fibers). Examples of graphite include mesophase microspheres, graphite whiskers, and flat graphite.

[0235] In the present invention, "flat plate shape" means a shape having two main planes facing in opposite directions.

[0236] As the metal composite oxide, a metal composite oxide capable of occluding and releasing lithium is preferred.

[0237] From the viewpoint of high current density charge and discharge characteristics, the metal composite oxide capable of occluding and releasing lithium preferably contains at least one element selected from the group consisting of titanium and lithium.

[0238] The metal oxide and the metal combination oxide are particularly preferably amorphous oxides.

[0239] The metal oxide and the metal combination oxide are also preferably chalcogenides. Chalcogenides are reaction products between metal elements and elements of Group 16 in the periodic table.

[0240] Among the compound group consisting of amorphous oxides and chalcogenides, amorphous oxides and chalcogenides of semimetallic elements are also preferred, and oxides and chalcogenides of 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.

[0241] The negative electrode active material preferably further contains titanium. The volume change during the storage and release of lithium ions is small, so the rapid charge and discharge characteristics are excellent, and from the perspective of suppressing the degradation of the electrode and increasing the life of the lithium ion secondary battery, the negative electrode active material containing titanium is preferably Li4Ti5O 12 (lithium titanate [LTO]).

[0242] The negative electrode active material may be a commercial product or a synthetic product produced by a known method (eg, calcination method). For example, the negative electrode active material obtained by calcination method may be washed with water, an acidic aqueous solution, an alkaline aqueous solution or an organic solvent.

[0243] The negative electrode active material is available as, for example, CGB20 (Nippon Graphite Industry Co., Ltd.).

[0244] The composition of the negative electrode active material was measured using inductively coupled plasma (ICP) emission spectrometry.

[0245] The shape of the negative electrode active material is not limited, but is preferably in the form of particles from the viewpoint of easy handling and easy control of uniformity during mass production.

[0246] 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.

[0247] The volume average particle size of the negative electrode active material is measured by a method based on the method for measuring the volume average particle size of the positive electrode active material described above.

[0248] Examples of methods for adjusting the particle size of the negative electrode active material include a method using a pulverizer or a classifier.

[0249] The negative electrode active material may be used alone or in combination of two or more.

[0250] Furthermore, even when a single type of negative electrode active material is used, negative electrode active materials having different particle sizes may be used in combination.

[0251] The content of the negative electrode active material relative to the total volume of the electrode material film is preferably 30% to 60% by volume, more preferably 35% to 57% by volume, and even more preferably 45% to 55% by volume.

[0252] In the method for producing an electrode molded body according to the present invention, the amount of the negative electrode active material used is determined so that the content in the electrode material film falls within the above range.

[0253] The surfaces of the positive electrode active material and the negative electrode active material may be coated with a surface coating agent, respectively. As the surface coating agent, for example, a metal oxide containing Ti, Nb, Ta, W, Zr, Si or Li may be cited. As the above-mentioned metal oxide, for example, titanate spinel, tantalum oxide, niobium oxide and lithium niobate compounds may be cited.

[0254] (Conductive additive)

[0255] The electrode material film contains a conductive auxiliary agent from the viewpoint of improving the electron conductivity of the electrode active material. The conductive auxiliary agent is not limited, and a known conductive auxiliary agent can be used.

[0256] The conductive auxiliary agent is contained in the solid component.

[0257] As conductive aids, for example, graphite (for example, natural graphite and artificial graphite), carbon black (for example, acetylene black, Ketjen black and furnace black), amorphous carbon (for example, needle coke), carbon fiber (for example, vapor-grown carbon fiber and carbon nanotube), other carbonaceous materials (for example, graphene and fullerene), metal powder (for example, copper powder and nickel powder), metal fiber (for example, copper fiber and nickel fiber) and conductive polymer (for example, polyaniline, polypyrrole, polythiophene, polyacetylene and polyphenylene derivatives) can be cited.

[0258] The conductive auxiliary agent may be used alone or in combination of two or more.

[0259] The content of the conductive aid relative to the total volume of the electrode material film 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.

[0260] In the method for producing an electrode molded body according to the present invention, the amount of the conductive auxiliary agent used is determined so that the content in the electrode material film falls within the above range.

[0261] (Electrolyte)

[0262] There is no particular limitation on the electrolyte, and a known electrolyte can be used. For example, an electrolyte containing an electrolyte and a solvent can be cited. As a specific electrolyte, for example, an electrolyte containing a lithium salt compound as an electrolyte and a carbonate compound as a solvent can be cited.

[0263] As the lithium salt compound, for example, lithium hexafluorophosphate can be mentioned. The electrolyte solution may contain a single lithium salt compound, or may contain two or more lithium salt compounds.

[0264] As carbonate compounds, for example, chain carbonate compounds such as ethyl methyl carbonate (also referred to as EMC), dimethyl carbonate (also referred to as DMC), diethyl carbonate (DEC) and cyclic carbonate compounds such as ethylene carbonate (also referred to as EC) and propylene carbonate (also referred to as PC) can be cited. The electrolyte can include a single carbonate compound, can include two or more carbonate compounds, and can also use more than one chain carbonate compound and more than one cyclic carbonate compound simultaneously.

[0265] As the electrolyte contained in the electrolytic solution, for example, a well-known inorganic solid electrolyte can be used.

[0266] As a component of the electrolytic solution, for example, an ionic liquid can be used. The ionic liquid can be used as an electrolyte or as a solvent.

[0267] The content of the electrolyte solution relative to the total volume of the electrode material film is preferably 48% by volume or less, may be 45% by volume or less, and may be 40% by volume or less.

[0268] The lower limit of the content of the electrolyte solution relative to the total volume of the electrode material film is not limited, and may be 28 volume % or more, or 30 volume % or more.

[0269] (Solvent)

[0270] The electrode material film may contain, as a liquid component, a solvent other than the solvent contained as a component of the electrolytic solution (hereinafter, also simply referred to as a “solvent”).

[0271] 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.

[0272] The boiling point of the solvent is preferably 50° C. or higher, more preferably 70° C. or higher, at normal pressure (ie, 1 atmosphere). The upper limit of the boiling point of the solvent is preferably 250° C. or lower, more preferably 220° C. or lower, at normal pressure (ie, 1 atmosphere).

[0273] The solvent may be used alone or in combination of two or more.

[0274] The content of the liquid component (ie, the electrolyte solution and the solvent) relative to the total volume of the electrode material film is preferably 48% by volume or less, may be 45% by volume or less, and may be 40% by volume or less.

[0275] The lower limit of the content of the liquid component relative to the total volume of the electrode material film is not limited, and may be 28 volume % or more, or 30 volume % or more.

[0276] In addition, the liquid component contained in the electrode material film, that is, the component in the electrode material film that is liquid at 25° C. is preferably liquid even at -10° C., and preferably liquid even at -20° C. That is, the component in the electrode material film that is liquid at 25° C. is preferably a component that does not solidify at -10° C., and preferably a component that does not solidify even at -20° C.

[0277] (Other ingredients)

[0278] The electrode material film may contain a binder, a dispersant, other additives, etc. in addition to the above components. However, from the viewpoint of improving energy density, the electrode material film preferably has a low binder content, and more preferably contains no binder.

[0279] Examples of the binder include fluorine-containing resins, hydrocarbon thermoplastic resins, acrylic resins, and urethane resins.

[0280] Furthermore, the dispersant may be any known dispersant as long as it can disperse the dispersion object.

[0281] Furthermore, as other additives, known additives added to electrodes can be used.

[0282] <<Molded article for sheet electrode>>

[0283] The sheet-shaped electrode molded body obtained by the method for producing a sheet-shaped electrode molded body according to the present invention can be used as various electrodes. In addition, the sheet-shaped electrode molded body can be used as an electrode as it is, or the sheet-shaped electrode molded body can be further processed to be used as an electrode.

[0284] The sheet-shaped molded body for an electrode is preferably a molded body for an electrode of a semi-solid secondary battery.

[0285] From the viewpoint of improving battery performance (eg, discharge capacity and output characteristics), the sheet-shaped electrode molded body preferably has a thickness of 70 μm to 230 μm and a solid content of 50 to 80 volume % similarly to the electrode material film.

[0286] The thickness of the sheet-shaped electrode molded body is measured by the same method as the thickness of the electrode material film. Furthermore, the solid content concentration of the sheet-shaped electrode molded body is calculated by the same method as the solid content concentration of the electrode material film.

[0287] The sheet-shaped electrode molded body obtained by the method for manufacturing an electrode molded body of the present invention is formed on a support, but in the sheet-shaped electrode molded body with a support, the smoothness of the support tends to be high. This is because, in the method for manufacturing an electrode molded body of the present invention, a sheet-shaped electrode molded body having a high solid content concentration can be manufactured, but a large pressure is not required during the process.

[0288] Specifically, when the support is a current collector, the arithmetic mean roughness Ra of the current collector in the sheet-shaped electrode molded body with a current collector is preferably 0.1 nm to 1000 nm, and more preferably 1 nm to 30 nm.

[0289] Furthermore, in the case where the support is a current collector, in the sheet-shaped electrode molded body with the current collector, a coating layer tends to be unnecessary on the surface. Usually, the coating layer of the current collector is provided to roughen the surface. By roughening the surface of the current collector, the adhesion to the material imparted to the current collector can be improved. In the method for manufacturing the electrode molded body involved in the present invention, a mixture containing particles is used, and since the mixture containing particles has good adhesion to the support, a coating layer in the current collector is unnecessary.

[0290] Therefore, when the support is a current collector, the current collector in the sheet-shaped electrode molded body with a current collector preferably has no coating layer.

[0291] Moreover, in the sheet-like electrode molded body, the content of the conductive aid having a needle-like shape or a fibrous shape tends to be high. In order to manufacture a sheet-like electrode molded body with a high solid content concentration, it is usually used after applying a very high pressure to an electrode material containing a large amount of solid components such as a conductive aid and an electrode active material and a small amount of electrolyte to uniformly disperse it. Due to the high pressure during the dispersion treatment, the needle-like shape or the fibrous shape of the conductive aid is destroyed (for example, cut), so there is little conductive aid having a needle-like shape or a fibrous shape remaining in the obtained sheet-like electrode molded body. In the manufacturing method of the electrode molded body involved in the present invention, by using particles, the dispersion treatment when obtaining the mixture can be carried out at a low pressure. As a result, in the sheet-like electrode molded body manufactured by the manufacturing method of the electrode molded body involved in the present invention, the content of the conductive aid having a needle-like shape or a fibrous shape becomes high.

[0292] Example

[0293] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

[0294] In addition, each process in each example mentioned later was performed in the drying room (low dew point room) of 22 degreeC.

[0295] [Preparation of combined granules (G1-1)]

[0296] Composite particles (G1-1) were obtained as follows.

[0297] A powder was prepared by mixing and dispersing 2 g of a conductive aid (Ketjen Black) and 174 g of a positive electrode active material (lithium iron phosphate), which was dry granulated using a roll press FT manufactured by FREUND-TURBO CORPORATION, and granulated products (particles) of a desired size were taken out using a sieve.

[0298] The volume average particle size of the obtained composite particles (G1-1) was 200 μm.

[0299] [Preparation of combined particles (G1-2) and (G1-3)]

[0300] In the preparation of the combined granules (G1-1), the conditions for taking out the granules (particles) of the desired size using a sieve were changed to obtain combined granules (G1-2) with a volume average particle size of 100 μm and combined granules (G1-3) with a volume average particle size of 500 μm.

[0301] [Preparation of Electrode Active Material Particles (G2)]

[0302] Granules (G2) were obtained as follows.

[0303] 176 g of the positive electrode active material (lithium iron phosphate) was dry-granulated using a roll press FT manufactured by FREUND-TURBO CORPORATION, and granulated materials (particles) having a desired size were taken out using a sieve.

[0304] The volume average particle size of the obtained particles (G2) was 200 μm.

[0305] [Preparation of Conductive Auxiliary Agent Particles (G3)]

[0306] Granules (G3) were obtained as follows.

[0307] 20 g of the conductive auxiliary agent (Ketjen Black) was dry-granulated using a roll press FT manufactured by FREUND-TURBO CORPORATION, and granulated products (granules) having a desired size were taken out using a sieve.

[0308] The volume average particle size of the obtained particles (G3) was 40 μm.

[0309] [Preparation of electrolyte (X)]

[0310] After LiPF6 (electrolyte) is mixed into a mixed solution of ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC), vinylene carbonate (VC) is further mixed to obtain an electrolyte solution (X).

[0311] [Preparation of support]

[0312] Support (S1): positive electrode current collector (aluminum foil, average thickness 20 μm, Ra 0.5 μm)

[0313] The Ra of the current collector mentioned above refers to the arithmetic mean roughness Ra of the surface on which the electrode material film is formed.

[0314] [Preparation of pressing parts]

[0315] Scraper (B1): Stainless steel scraper

[0316] <Example 1>

[0317] Using a mixer (Awatori Rentaro ARE-310, manufactured by THINKY CORPORATION), 120 g of the composite particles (G1-1) and 32 g of the electrolyte (X) were stirred and mixed at 700 rpm (revolutions per minute, the same below) for 1 minute to obtain a mixture (M1).

[0318] like Figure 1 As shown, the mixture (M1) was applied onto the transported support (S1) using a twin-shaft screw feeder manufactured by Seiwa Giken Co., Ltd., thereby forming a film having a thickness of about 300 μm.

[0319] Then, if Figure 1 As shown in FIG. 1 , the film formed on the support was pressed using a scraper (B1). Specifically, the scraper 30 was arranged so that the distance between the surface of the support 10 and the tip of the scraper 30 was 200 μm. Figure 1 As shown, the support 10 is conveyed in the direction of arrow X, and the film 24 formed on the support 10 is brought into contact with the squeegee 30 and passed through the gap. Thus, an electrode material film of 200 mm×150 mm×200 μm (thickness) is formed on the support.

[0320] The solid content concentration of the obtained electrode material film was 56% by volume.

[0321] <Example 2>

[0322] 118.6 g of the electrode active material particles (G2) and 1.4 g of the conductive aid (Ketjen Black) were mixed and dispersed, and 120 g of the obtained mixture and 32 g of the electrolyte (X) were stirred and mixed at 700 rpm for 1 minute using a mixer (Awatori Rentaro ARE-310, manufactured by THINKY CORPORATION) to obtain a mixture (M2).

[0323] An electrode material film of 210 mm×150 mm×200 μm (thickness) was formed on a support in the same manner as in Example 1 except that the obtained mixture (M2) was used.

[0324] The solid content concentration of the obtained electrode material film was 56% by volume.

[0325] <Example 3>

[0326] 1.4 g of conductive auxiliary agent particles (G3) and 118.6 g of positive electrode active material (lithium iron phosphate) were mixed and dispersed. Using a mixer (Awatori Rentaro ARE-310, manufactured by THINKY CORPORATION), 120 g of the obtained mixture and 32 g of the electrolyte (X) were stirred and mixed at 700 rpm for 1 minute to obtain a mixture (M3).

[0327] An electrode material film of 210 mm×150 mm×200 μm (thickness) was formed on a support in the same manner as in Example 1 except that the obtained mixture (M3) was used.

[0328] The solid content concentration of the obtained electrode material film was 56% by volume.

[0329] <Example 4>

[0330] (1) After LiPF6 (electrolyte) was mixed into a mixed solution of ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC), vinylene carbonate (VC) was further mixed in. 64 g of the obtained mixed solution was taken out and used as electrolyte X1.

[0331] (2) Using a mixer (Awatori Rentaro ARE-310, manufactured by THINKY CORPORATION), 0.4 g of a conductive agent (Ketjen Black) and 34.1 g of a positive electrode active material (lithium iron phosphate) were stirred at 1500 rpm for 30 seconds to prepare a kneaded product Y1 (34.5 g).

[0332] (3) Electrolyte X1 (64 g) was added to kneaded product Y1 (81 g), and the mixture was stirred at 1500 rpm for 120 seconds using a mixer (Awatori Rentaro ARE-310, manufactured by THINKY CORPORATION) to obtain a positive electrode material (1-1).

[0333] The volume ratio of the solid content to the liquid content of the obtained positive electrode material (1-1) was 15:85.

[0334] Then, if Figure 2 As shown, the positive electrode material (1-1) was applied onto the transported support (S1) using a doctor blade to form a film 50 having a solid content concentration of 15% by volume and a thickness of 100 μm.

[0335] Then, the composite particles (G1-1) were applied to the film 50 using an electromagnetic feeder (linear feeder manufactured by SINFONIA TECHNOLOGY CO., LTD.) to a thickness of 100 μm.

[0336] Then, in the same manner as in Example 1, the film formed on the support was pressed using a doctor blade (B1), thereby forming an electrode material film of 200 mm×150 mm×200 μm (thickness) on the support.

[0337] The solid content concentration of the obtained electrode material film was 57.5% by volume.

[0338] <Example 5>

[0339] like Figure 2 As shown, the electrolyte solution (X) was applied onto the transported support (S1) using a doctor blade to form a film 50 having a solid content concentration of 0 volume % and a thickness of 85 μm.

[0340] Then, the composite particles (G1-1) were applied to the film 50 using an electromagnetic feeder (linear feeder manufactured by SINFONIA TECHNOLOGY CO., LTD.) so as to have a thickness of 115 μm.

[0341] Then, in the same manner as in Example 1, the film formed on the support was pressed using a doctor blade (B1), thereby forming an electrode material film of 200 mm×150 mm×200 μm (thickness) on the support.

[0342] The solid content concentration of the obtained electrode material film was 57.5% by volume.

[0343] <Example 6 and Example 7>

[0344] An electrode material film having a thickness of 200 μm and a solid content concentration of 56 vol % was obtained on a support in the same manner as in Example 1 except that the composite particle (G1-1) was changed to the composite particle (G1-2) or the composite particle (G1-3).

[0345] [evaluate]

[0346] Homemade Figure 4 The image inspection device 70 shown is provided with a CCD camera 72 and a line illumination 74. The moldability of the electrode material film (molded body for sheet-shaped electrode) was evaluated using the image inspection device 70.

[0347] In the image inspection device 70, the support 10 formed with the electrode material film 100 is placed on the XY stage 76, and the entire surface (i.e., the entire upper surface) of the electrode material film 100 can be photographed using the CCD camera 72 and the line illumination 74 provided on the upper part of the electrode material film 100. Here, the electrode material film 100 can be moved in the XY direction by the XY stage 76, and the CCD camera 72 and the line illumination 74 can be moved in the Z direction by the connected Z-axis guide 78.

[0348] The image inspection device 70 was used to move the electrode material film 100, the CCD camera 72, and the line illumination 74 respectively through the XY stage 76 and the Z-axis guide 78, and 140 images were taken of the entire surface of the electrode material film 100 of 210 mm × 150 mm obtained in the above examples with a 16 mm square field of view. In addition, when the electrode material film is greatly damaged, a change in color tone is observed in the photographed image, so the damage can be detected by the change in color tone. In addition, when the electrode material film 100 is slightly damaged, light is scattered in the electrode material film at the damaged part, so the damage can be detected by the scattering of the light.

[0349] By the above method, camera images (140 images) of the entire surface of the electrode material film were obtained, and the number of camera images in which damage was observed was counted. The ratio of the number of camera images in which damage was observed to the total number of camera images (140 images) of the entire surface of the electrode material film was obtained, and the formability was evaluated according to the following criteria. The smaller the ratio of the number of camera images in which damage was observed, the better the formability can be evaluated. In the present invention, the ratio of the number of camera images in which damage was observed is preferably less than 10%. The results are shown in Table 1.

[0350] -Evaluation Criteria-

[0351] A: The ratio of the number of captured images in which damage was observed was 1% or less.

[0352] B: The ratio of the number of captured images in which damage was observed was more than 1% and 3% or less.

[0353] C: The ratio of the number of captured images in which damage was observed was more than 3% and 5% or less.

[0354] D: The ratio of the number of captured images in which damage was observed was more than 5% and 10% or less.

[0355] E: The ratio of the number of captured images in which damage was observed exceeded 10%.

[0356] [Table 1]

[0357]

[0358] From Table 1, it can be seen that the moldability is excellent by using pellets. It can be seen that the moldability is further excellent by using combined pellets among the pellets.

[0359] Explanation of symbols

[0360] 10-support body, 20-imparting mechanism, 22-mixture containing particles, 24-film based on mixture containing particles, 30-scraper, 40-imparting mechanism, 42-combined particles, 44-film based on combined particles, 50-electrolyte-based film, 60-pressing roller, 62-film, 70-image inspection device, 72-CCD camera, 74-line lighting, 76-XY stage, 78-Z-axis guide, 100-electrode material film, 102-pressurized electrode material film, X-conveying direction of support body.

[0361] The invention of Japanese Patent Application No. 2022-120970 filed on July 28, 2022 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each document, patent application, and technical standard were specifically and individually described by reference.

Claims

1. A method for producing a sheet-shaped electrode molded body, comprising: In the first step, particles containing one or both of an electrode active material and a conductive additive are prepared; and In the second step, a mixture of an electrode active material, a conductive auxiliary agent and an electrolyte solution is obtained using the particles prepared in the first step. An electrode material film including an electrode active material, a conductive auxiliary agent and an electrolyte solution is formed on a support.

2. The method for producing a sheet-shaped electrode molded body according to claim 1, wherein: The first step includes a granulation step of granulating one or both of the electrode active material and the conductive auxiliary agent.

3. The method for producing a sheet-shaped electrode molded body according to claim 2, wherein: The maximum filling rate of the granules obtained in the granulation step is 55 volume % to 95 volume %.

4. The method for producing a sheet-shaped electrode molded body according to claim 2 or 3, wherein: The granulation step is a step of combining the electrode active material and the conductive auxiliary agent and granulating them.

5. The method for producing a sheet-shaped electrode molded body according to claim 4, wherein: The volume average particle size of particles obtained by combining the electrode active material and the conductive auxiliary agent and granulating them is 10 μm to 1000 μm.

6. The method for producing a sheet-shaped electrode molded body according to claim 2 or 3, wherein: The granulation step is a step of granulating one of the electrode active material and the conductive auxiliary agent, or granulating both the electrode active material and the conductive auxiliary agent.

7. The method for producing a sheet-shaped electrode molded body according to claim 6, wherein: The volume average particle size of the particles obtained by granulating the electrode active material is 10 μm to 1000 μm.

8. The method for producing a sheet-shaped electrode molded body according to claim 6, wherein: The volume average particle size of the particles obtained by granulating the conductive auxiliary agent is 0.2 μm to 50 μm.

9. The method for producing a sheet-shaped electrode molded body according to claim 2, wherein: The granulation was carried out by dry granulation.

10. The method for producing a sheet-shaped electrode molded body according to claim 2, wherein: Granulation is performed by a wet granulation method using at least a part of the electrolyte.

11. The method for producing a sheet-shaped electrode molded body according to claim 1 or 2, wherein: The mixture obtained in the second step is applied to a support to form an electrode material film containing an electrode active material, a conductive auxiliary agent, and an electrolyte solution on the support.

12. The method for producing a sheet-shaped electrode molded body according to claim 1 or 2, wherein: The second step is a step of providing the particles prepared in the first step onto a support to obtain a mixture of an electrode active material, a conductive auxiliary agent, and an electrolyte solution on the support.

13. The method for producing a sheet-shaped electrode molded body according to claim 1 or 2, wherein: The method includes applying pressure or vibration to a mixture of an electrode active material, a conductive auxiliary agent and an electrolyte solution disposed on a support.

14. The method for producing a sheet-shaped electrode molded body according to claim 1 or 2, wherein: The electrode material film has a thickness of 70 μm to 230 μm and a solid content concentration of 50 volume % to 80 volume %.

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