WO2024024735A1 - シート状電極用成形体の製造方法 - Google Patents
シート状電極用成形体の製造方法 Download PDFInfo
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- WO2024024735A1 WO2024024735A1 PCT/JP2023/027039 JP2023027039W WO2024024735A1 WO 2024024735 A1 WO2024024735 A1 WO 2024024735A1 JP 2023027039 W JP2023027039 W JP 2023027039W WO 2024024735 A1 WO2024024735 A1 WO 2024024735A1
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- Prior art keywords
- support
- electrode material
- electrode
- lumps
- sheet
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
- H01M4/0402—Methods of deposition of the material
- H01M4/0404—Methods of deposition of the material by coating on electrode collectors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
- H01M4/043—Processes of manufacture in general involving compressing or compaction
- H01M4/0433—Molding
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/661—Metal or alloys, e.g. alloy coatings
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Definitions
- the present disclosure relates to a method for manufacturing a molded body for a sheet-like electrode.
- Electrodes applied to semi-solid batteries are manufactured using, for example, an electrode material containing at least an electrode active material in the form of a powder and an electrolyte.
- Japanese Patent Laid-Open No. 2014-186969 discloses an electrode including means for supplying powder made of granulated particles containing an electrode active material, a binder, and a conductive material onto a support using a brush-like member.
- a manufacturing apparatus is disclosed.
- JP-A No. 2021-027043 discloses that an electrode composition layer arrangement portion in which an electrode composition layer made of an electrode composition containing an electrode active material is arranged on the surface of a continuous sheet-like base material is arranged intermittently.
- a method for producing an electrode material for a lithium ion battery comprising: a supply step of continuously supplying the electrode composition onto the base material; and the electrode composition supplied onto the base material by the supply step.
- a pressurizing step to obtain the electrode composition layer, and a part of the electrode composition supplied onto the base material in the supply step is removed to arrange the electrode composition layer on the base material.
- a method for producing an electrode material for a lithium ion battery which includes a removing step of forming a portion.
- an electrode material containing at least an electrode active material in the form of a powder (an example of a solid component) and an electrolyte (an example of a liquid component) is used, and the electrode material is placed on a support.
- This process involves (1) a method of extruding the electrode material onto a support with the same thickness as the sheet-like electrode molded body to be manufactured, or (2) a method of extruding the electrode material onto a support body with a thickness greater than that of the sheet-like electrode molded body to be manufactured.
- a method is adopted in which the electrode material is extruded onto a support and the thickness of the extruded electrode material is adjusted on the support.
- the electrode materials used in the production of semi-solid batteries contain a larger amount of powdered electrode active material than the electrolyte and exhibit clay-like properties.
- an electrode material with clay-like properties to the method (2) above unlike the method (1) above, it is necessary to extrude the electrode material from a long and narrow rectangular discharge port by applying strong pressure. There isn't.
- the thickness of the extruded electrode material is reduced by scraping off the excess with a molding member such as a blade, or pressing it with a press, and then discharging the excess outside of the support.
- a molding member such as a blade
- a press machine since the electrode material has clay-like properties, a large load is required when deforming the electrode material using a molding member or a press machine. That is, as described above, methods (1) and (2) above include a process of applying a large load to the electrode material. In order to apply a large load to the electrode material, the device or member that holds the electrode material must be made larger and more robust. Furthermore, when a large load is applied, the solid component and liquid component of the electrode material may separate, making it difficult to form an electrode material film with a desired thickness.
- An object of an embodiment of the present disclosure is to provide a method for manufacturing a sheet-like electrode molded body that reduces the load applied to the electrode material and can produce a sheet-like electrode molded body with a desired thickness. shall be.
- a method for producing a molded body for a sheet-like electrode comprising: ⁇ 2> By relatively moving the molded member along the support surface while maintaining a constant distance from the support surface, a plurality of lumps dispersedly arranged on the support are combined, The method for producing a sheet-like electrode molded body according to ⁇ 1>, which comprises forming an electrode material film on a support.
- ⁇ 5> In any one of ⁇ 1> to ⁇ 4>, in which the distance between the area centroids of adjacent lumps is 0.1 mm to 50 mm in a plurality of lumps distributed and arranged on the support.
- Step A is carried out by scattering and supplying a plurality of lumps of electrode material containing an electrode active material and an electrolyte solution and having a solid component concentration of 20% to 90% by volume onto a support.
- Steps A and B are performed using a continuously conveyed support, and in Step B, an electrode material film is formed as a continuous film along the conveyance direction of the support, ⁇ 1> to ⁇ 7 >The method for producing a molded body for a sheet-like electrode according to any one of the above.
- X be the theoretical amount of electrode material that can form an electrode material film with the same thickness as the distance between the molded member and the surface of the support and without any gaps, and add a lump of electrode material onto the support.
- the supply amount is Y
- the ratio (Y/X) of the supply amount Y to the amount X satisfies 1 ⁇ Y/X ⁇ 5 on a volume basis Method for manufacturing a molded object.
- a method for manufacturing a sheet-like electrode molded body that can reduce the load applied to the electrode material and can manufacture a sheet-like electrode molded body with a desired thickness. Can be done.
- FIG. 1 is a schematic diagram showing an example of the form of a lump.
- FIG. 2 is a schematic cross-sectional view of a state in which a plurality of lumps are dispersed and arranged on a support, taken along the thickness direction of the support.
- FIG. 3 is a schematic top view of a state in which a plurality of lumps are dispersed and arranged on a support, as viewed from above.
- FIG. 4 is a schematic cross-sectional view for explaining a method of uniting a plurality of lumps distributed on a support using a molded member.
- FIG. 5 is a schematic top view for explaining a method of uniting a plurality of lumps distributed on a support using a molding member.
- a numerical range expressed using “ ⁇ ” means a range that includes the numerical values written before and after " ⁇ " as lower and upper limits.
- the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described step by step.
- the upper limit or lower limit described in a certain numerical range may be replaced with the value shown in the Examples.
- the term “process” includes not only an independent process but also a process that is not clearly distinguishable from other processes, as long as the intended purpose of the process is achieved. .
- (meth)acrylic means both acrylic and methacrylic, or either one.
- the amount of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified. .
- a combination of two or more preferred aspects or forms is a more preferred aspect or form.
- the term “solid component” refers to a component that is solid at 25°C and 1 atm
- the term “liquid component” refers to a component that is liquid at 25°C and 1 atm.
- the region where the electrode material film is formed on the support refers to the region of the total surface area of the support where the electrode material film is formed by coalescing the lumps of the electrode material. This corresponds to the area covered by the electrode material film.
- the support is a current collector or a laminate of a current collector and a resin film, the area of the current collector becomes the formation area of the electrode material film.
- the "width direction" of a support refers to a direction perpendicular to the longitudinal direction, and in the case of a long support, refers to a direction perpendicular to the longitudinal direction.
- the "width direction" of a film forming member refers to a direction perpendicular to the direction in which the film forming member moves relative to the surface of the support (i.e., the direction in which the electrode material film is formed on the support). refers to That is, the "width direction” of the blade also corresponds to the "width direction” of the electrode material film.
- a method for producing a sheet-like electrode molded body according to the present disclosure includes a plurality of lumps of an electrode material containing an electrode active material and an electrolyte and having a solid component concentration of 20% to 90% by volume on a support.
- the method includes a step A of dispersing and arranging the plurality of lumps on the support, and a step B of uniting the plurality of lumps dispersed and arranged on the support using a molding member to form an electrode material film on the support.
- an electrode material containing an electrode active material and an electrolytic solution and having a solid component concentration of 20% to 90% by volume is also referred to as “specific electrode material”
- sheet-shaped electrode molded body is simply referred to as “specific electrode material”.
- electrode molded body also called “electrode molded body”.
- An electrode material containing an electrode active material and an electrolyte and having a solid component concentration of 20% to 90% by volume exhibits clay-like properties.
- the present inventors investigated a method of obtaining a sheet-like electrode molded body with a desired thickness without applying a large load to the electrode material using such an electrode material exhibiting clay-like properties. .
- the contact area between the molded member and the lump is small, and it is considered that the load applied from the molded member to the electrode material is small.
- an electrode material film having a desired thickness can be formed by adjusting the molding member.
- a sheet-like electrode molded body having a desired thickness can be formed without applying a large load to the electrode material.
- JP-A-2014-186969 the powder supplied onto the support contains a small amount of electrolyte and does not fall under the specific electrode material. Furthermore, JP-A-2021-027043 does not describe that a plurality of lumps dispersedly arranged on a support are united by a molding member to form an electrode material film on the support. .
- step A a plurality of lumps of an electrode material (i.e., specific electrode material) containing an electrode active material and an electrolyte and having a solid component concentration of 20% by volume to 90% by volume are dispersed on a support. have it placed.
- an electrode material i.e., specific electrode material
- agglomerates of electrode material refer to granules (also referred to as pellets) having a diameter of 0.1 mm to 20 mm, or secondary particles thereof (ie, aggregates).
- the particles having a diameter of 0.1 mm to 20 mm are particles made of a mixture containing at least an electrode active material and an electrolyte.
- FIG. 1 is a schematic diagram showing an example of the form of a lump.
- the lump 20 is, for example, an aggregate formed by agglomerating three granules 22.
- the number of granules 22 included in the lumps 20 is not particularly limited.
- the diameter of the granular material means the equivalent circle diameter of the granular material.
- the shape of the granules is not particularly limited, and may be spherical, ellipsoidal, cylindrical, flat, irregular, or the like.
- FIG. 2 is a schematic cross-sectional view of a state in which a plurality of lumps are dispersedly arranged on a support, taken along the thickness direction of the support.
- FIG. 3 is a schematic top view of a state in which a plurality of lumps are dispersedly arranged on a support, as viewed from above.
- the diameter of the lumps dispersedly arranged on the support is, for example, preferably 0.1 mm to 20 mm, more preferably 0.5 mm to 10 mm, and even more preferably 1 mm to 5 mm. preferable.
- a known method for determining the equivalent circle diameter is used to measure the diameter of the lump.
- the diameter of the agglomerate means the equivalent circle diameter of the agglomerate.
- the average height of the aggregates dispersedly arranged on the support is, for example, preferably 0.1 mm to 10 mm, more preferably 0.5 mm to 10 mm, and 1 mm to 5 mm. is even more preferable.
- the height of the lump corresponds to "H" in FIG.
- the height of the lump is determined by measurement using a laser displacement meter using the support as a reference.
- the measurement is performed on randomly selected 50 number % of the lumps (rounded down to the nearest whole number).
- the arithmetic mean value of the measured values obtained is defined as the "average height of the lump".
- the distance between the area centroids of adjacent aggregates is preferably 0.1 mm to 50 mm, more preferably 1 mm to 20 mm, and 5 mm to 20 mm. More preferably, it is 10 mm.
- the distance between the area centroids of adjacent lumps corresponds to "D" in FIG. 3.
- the distance between the area centroids of adjacent lumps is determined by obtaining an image of the support in which the lumps are dispersed when viewed from above, and identifying one lump (reference lump) in this image. , is determined by selecting the nearest adjacent lumps (proximate lumps) to the grain and measuring the distance between the area centroids (20C in FIG. 3) of these adjacent lumps.
- the above-mentioned reference lumps are lumps whose number corresponds to 25 number % (rounded down to the nearest whole number) when the total number of lumps existing on the area where the electrode material film is formed on the support is 100 number %. Select. When selecting this reference lump, the once-selected reference lump and its neighboring lumps are excluded. The arithmetic mean value of the obtained measured values is defined as the "distance between the area centroids of adjacent lumps."
- an image of the support when viewed from the top is A two-dimensional image obtained by joining together images of one line obtained by line sensor cameras provided along the width direction may be used.
- the area occupied by the plurality of aggregates dispersedly arranged on the support (hereinafter also referred to as area ratio of the aggregates) is 10% to 90% of the area on the support where the electrode material film is formed. It is preferably from 10% to 40%, even more preferably from 10% to 20%.
- the region where the electrode material film is formed on the support refers to the region of the total surface area of the support where the electrode material film is formed by combining the lumps of the electrode material, and the region where the electrode material film is formed on the support. This corresponds to the area covered by the material film. Note that if the support is a current collector or a laminate of a current collector and a resin film, the area of the current collector becomes the formation area of the electrode material film.
- the area ratio of the lumps is determined as follows. That is, first, an image of the support in which the aggregates are dispersed is obtained when viewed from above, this image is binarized, and the area occupied by the aggregates on the support is calculated. Then, the calculated area occupied by the lumps is calculated by introducing the formula: Area occupied by the lumps/formation area of the electrode material film on the support x 100. In addition, in the case of an embodiment in which an electrode material film is continuously formed on a continuously conveyed support along the conveyance direction of the support, adjacent lumps are In the same way as when calculating the distance between the center of gravity of an object, a two-dimensional image obtained using a line sensor camera may be used.
- step A there are no particular restrictions on the method of dispersing and arranging a plurality of lumps of the specific electrode material on the support, but from the viewpoint of easy adjustment of the size of the lumps, and the method of dispersing the lumps. From the viewpoint of easy adjustment and stabilization of the supply amount, it is preferable to carry out the following method. That is, step A is preferably carried out by scattering and supplying a plurality of lumps of the specific electrode material onto the support. That is, by scattering and supplying a plurality of lumps of the specific electrode material prepared in advance onto the support, the plurality of lumps of the specific electrode material can be dispersed and arranged on the support.
- the plurality of lumps of the specific electrode material used for the above-mentioned scattering supply can be manufactured by a known granulation means that can be granulated using the specific electrode material.
- a known granulation means examples include extrusion granulation, pulverization granulation, compression granulation, wet (agglomeration) granulation, and granulation using a dicer.
- the agglomerates obtained by the granulation means are distributed and supplied onto the support by known conveyance means and supply means. Furthermore, the dispersion and supply can be performed by relatively moving the supply means along the surface of the support.
- step B a plurality of lumps distributed on the support are combined by a molding member to form an electrode material film on the support.
- a molding member to form an electrode material film on the support.
- step B by moving the molded member relatively along the support surface while maintaining a constant distance from the support surface, a plurality of lumps distributed on the support are combined.
- FIG. 4 is a schematic cross-sectional view for explaining a method of uniting a plurality of lumps dispersedly arranged on a support body using a molded member.
- FIG. 5 is a schematic top view for explaining a method of uniting a plurality of lumps dispersedly arranged on a support body using a molding member.
- the blade an example of a molded member
- the blade 30 is installed so as to maintain a constant distance from the surface of the support 10.
- the distance between the tip of the blade 30 specifically, the corner of the blade 30 closest to the surface of the support 10
- the surface of the support 10 will also be referred to as "distance C".
- a gap having a distance C is formed between the surface of the support 10 and the tip of the blade 30.
- the electrode material film 24 formed as described above is not limited to having a width equivalent to the width of the blade 30, as shown in FIG.
- the width of the electrode material film 24 can be made smaller than the width of the blade 30 by adjusting the arrangement of the lumps 20 on the support 10, the amount of supply, etc. You can also do it.
- the installation position of the blade may be determined based on the distance C set according to the thickness of the electrode material film to be formed.
- “keep a certain distance from the support surface” means that when the blade is moving relative to the support surface, the distance between the support surface and the tip of the blade at the center in the width direction is It suffices if it is kept substantially constant.
- “to maintain a certain distance from the support surface” includes changes in the position of the support surface when the support is transported (position changes caused by floating of the support and wrinkles on the support), Surface roughness on the body surface is also acceptable.
- the distance between the support surface and the tip of the blade when the blade is stopped i.e., the height of the gap
- the variation value of the distance between the support surface and the tip of the blade during relative movement of the blade along the surface is within 3% or 20 ⁇ m or less, this is allowed.
- the distance between the support surface and the tip of the blade i.e., the height of the gap
- the blade is preferably connected to a pressurizing means (not shown).
- This pressurizing means directs the blade toward the support so as to maintain a constant distance C even when the blade is in contact with a lump or when the blade is moving relative to the surface of the support. It is preferable to apply pressure. Further, it is preferable to apply pressure to the blade so as to maintain a constant distance C and to oppose the repulsive force from the lump that is in contact with it (that is, the force that pushes the blade away from the lump).
- the electrode material film is formed by the lump passing through the gap having the distance C, and at this time, it is preferable that at least the contact portion of the blade with the lump is vibrating. Since the contact portion of the blade with the lump is vibrating, this vibration is propagated to the lump, and shearing force is applied to the lump. It is presumed that the viscosity of the aggregates subjected to shearing force decreases and the fluidity improves, so that the coalescence of the aggregates is promoted. Further, in this embodiment, the surface condition of the formed electrode material film is uniform, and an electrode material film with less variation in thickness is formed.
- the vibrator for vibrating the blade is not particularly limited as long as it can vibrate at least the part of the blade in contact with the lump, and examples include pneumatic vibrators, motor vibrators, piezo vibrators, and ultrasonic vibrators. Examples include a vibrator.
- FIGS. 4 and 5 show a mode in which the support body 10 is conveyed and moved in the direction of the arrow X with respect to the fixed blade 30, the present invention is not limited to this mode.
- the support surface and the blade move relative to each other, and in addition to the above embodiment, the blade may be moved in one direction with respect to a fixed support.
- both the support body and the blade may be moved in one direction.
- a long support is used, and the long support is It is preferable to transport and move.
- FIGS. 4 and 5 show an embodiment in which a blade is used as the molded member
- the present invention is not limited to this embodiment.
- the forming member include a roller as well as a blade.
- the roller may be installed at a constant distance from the surface of the support, similar to the blade. The roller can rotate while contacting a plurality of lumps dispersedly arranged on the support to spread the lumps on the support. As a result, the plurality of lumps spread on the support unite together to form an electrode material film.
- the average height of the plurality of lumps distributed on the support is set to H, and the distance between the molded member and the surface of the support is set to C.
- the ratio of height H to distance C preferably satisfies 1 ⁇ H/C ⁇ 100, and satisfies 1 ⁇ H/C ⁇ 50. It is more preferable that 1 ⁇ H/C ⁇ 10 be satisfied.
- the distance C is determined by measurement using a laser displacement meter based on the height at which the blade contacts the support. Alternatively, the distance C may be measured using a mechanical gauge.
- step B when the lump comes into contact with the molded member, pressure is applied from the molded member to the lump, that is, the specific electrode material.
- the pressure applied to the lump that is in contact with the molded member, that is, the specific electrode material is preferably 10 kPa to 500 kPa, more preferably 10 kPa to 100 kPa, and preferably 10 kPa to 20 kPa. More preferred.
- the pressure applied to the electrode material is determined by the following method.
- the molded member is pressed with a constant force against a mass (i.e., electrode material) dispersedly arranged on a support using an actuator (air cylinder, motor-driven linear actuator, piezo, etc.), Furthermore, it is determined by dividing the force exerted by the actuator when relatively moving the molding member along the support surface to form an electrode material film of a desired thickness by the pressure-receiving area of the electrode material.
- a mass i.e., electrode material
- an actuator air cylinder, motor-driven linear actuator, piezo, etc.
- the method of changing the pressure applied to the lump that is in contact with the molded member, that is, the specific electrode material includes the distance between the support surface and the molded member, the pressure with which the molded member is pressed toward the support surface, Examples include methods of adjusting one or more factors, such as the weight of the molded member.
- Step A and Step B are performed using a continuously conveyed support, and in Step B, an electrode material film that is a continuous film is formed along the conveyance direction of the support. It is preferable to form Moreover, it is preferable to carry out step A by distributing and supplying a plurality of lumps of the specific electrode material onto a continuously conveyed support. In this preferred embodiment, the electrode material film is continuously formed on the continuously transported support along the transport direction of the support. By employing this aspect, the electrode material film can be formed with high productivity.
- the theoretical amount of electrode material that can form an electrode material film with the same thickness as the distance between the molded member and the surface of the support and without gaps is defined as X, and the amount of electrode material on the support is It is preferable that the ratio of the supply amount Y to the amount X (Y/X) satisfies 1 ⁇ Y/X ⁇ 5 on a volume basis.
- the value of the ratio (Y/X) may be adjusted as appropriate within the above range.
- the value of the ratio (Y/X) can be adjusted by changing the supply amount Y.
- the supply amount Y may be the same or different while the process A is being performed.
- a supply means for example, a pump, a feeder, etc.
- the method for manufacturing an electrode molded body according to the present disclosure may include other steps.
- Other steps include, for example, a step of pressurizing the electrode material film, and when the support is a release paper, a step of transferring the electrode material film formed on the release paper to a current collector.
- the method for manufacturing an electrode molded body according to the present disclosure may include a step of pressurizing the electrode material film obtained in step B.
- the pressurizing step By including the pressurizing step in the method for producing a molded body for an electrode according to the present disclosure, it is possible to increase the density of the electrode material and to make the density and thickness uniform within the plane.
- Examples of the pressure means used in this step include a pair of pressure rolls and a press machine.
- 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.
- the electrode material film may be pressed in stages using a plurality of pressure means (for example, a pair of pressure rolls).
- a plurality of pressure means for example, a pair of pressure rolls.
- This step is preferably carried out by relatively moving the pressurizing means and the electrode material film (specifically, the support on which the electrode material film is formed).
- “relatively moving the pressurizing means and the electrode material film” means moving the pressurizing means in one direction with respect to the electrode material film, and moving the electrode material film in one direction with respect to the pressurizing means.
- the method includes moving the pressure means and the electrode material film in one direction, respectively, but it is preferable to move the electrode material film in one direction with respect to the pressure means.
- the means for moving the electrode material film (specifically, the support on which the electrode material film is formed) is not limited, and any known conveying means can be used, such as a belt conveyor, linear motion guide, and cross roller. A table is mentioned.
- the electrode material film heated at, for example, 30° C. to 100° C. may be pressurized.
- the support used in this step is not particularly limited as long as it can form an electrode material film on its surface.
- a long support it is preferable to use a long support.
- its width may be determined depending on the size of the electrode material film and the width (length) of the widthwise central portion of the molded member (for example, a blade).
- a current collector is preferred as the support.
- the current collector which is an example of the support, is not particularly limited, and known current collectors (positive electrode current collector and negative electrode current collector) can be used.
- Examples of the positive electrode current collector include aluminum, aluminum alloy, stainless steel, nickel, and titanium.
- the positive electrode current collector is preferably made of aluminum or an aluminum alloy.
- the positive electrode current collector may be made of aluminum having a coating layer containing one or more of carbon, nickel, titanium, silver, gold, platinum, and vanadium oxide on the surface.
- Examples of the negative electrode current collector include aluminum, copper, copper alloy, stainless steel, nickel, and titanium.
- the negative electrode current collector is preferably made of aluminum, copper, a copper alloy, or stainless steel, and more preferably copper or a copper alloy.
- the negative electrode current collector may be made of copper or stainless steel, with a coating layer containing one or more of carbon, nickel, titanium, silver, and lithium on the surface.
- the current collector is preferably aluminum foil (including aluminum foil having the above-mentioned coating layer on the surface) or copper foil (including copper foil having the above-mentioned coating layer on the surface).
- Aluminum foil is commonly utilized as a current collector in positive electrodes.
- Copper foil is typically utilized as a current collector in the negative electrode.
- the support may be a laminate of a metal layer exemplified as the above-mentioned positive electrode current collector or negative electrode current collector and a resin film.
- Resin films used in the laminate include polyethylene terephthalate (PET) film, polypropylene (PP) film, polyethylene (PE) film, cyclic olefin polymer (COP, COC) film, triacetyl cellulose (TAC) polyimide (PI) film. and resin films such as polyamide (PA) films.
- a mold release material is mentioned as an example of a support.
- the release material which is an example of a support, include release paper (for example, release paper manufactured by Lintec Corporation), a film having a release layer, and paper having a release layer. preferable. Note that when a mold release material is used as a support, the electrode material film formed on the mold release material can be transferred to the current collector using the mold release property of the mold release material.
- the average thickness of the support (preferably the current collector) is preferably 3 ⁇ m or more, more preferably 5 ⁇ m or more, and particularly preferably 10 ⁇ m or more from the viewpoint of transportability. From the viewpoint of flexibility and lightness, the average thickness is preferably 100 ⁇ m or less, more preferably 70 ⁇ m or less, and particularly preferably 50 ⁇ m or less.
- the average thickness of the support is the arithmetic mean of the thicknesses at three locations measured by cross-sectional observation. In cross-sectional observation, a known microscope (for example, a scanning electron microscope) can be used.
- the size of the support is not limited and may be determined depending on the size of the electrode molded body to be manufactured, the size of various members used in the manufacturing process, etc.
- the transport mechanism for the support is not limited, and any known transport means can be used.
- a transport mechanism for the support for example, a belt conveyor, a linear motion guide, a cross roller table, etc. can be used.
- Forming members include blades and rollers. Among these, blades are preferred from the viewpoint of effectively uniting the lumps.
- the blade is a plate-shaped member, but the shape, size, material, etc. of the contact part that comes into contact with the lump depends on the type of electrode material (type of electrode active material, solid component concentration, composition of electrolyte solution, etc.). (viscosity, surface tension, etc.) may be determined as appropriate depending on the size, thickness, etc. of the electrode material film to be formed. Further, it is preferable that the electrode material is difficult to adhere to the contact portion of the blade with the lump, and for example, it is preferable that at least the surface of the blade exhibits mold releasability.
- the blade may be made of a fluororesin such as polytetrafluoroethylene (PTFE), a resin such as polyetheretherketone (PEEK), or a metal such as stainless steel, aluminum, iron, cemented carbide, etc. It may be made of aluminum or ceramic. Further, in order to impart mold releasability to the surface, the blade may include a surface layer exhibiting mold releasability (for example, a surface layer containing a fluororesin, a surface layer containing silicon particles and a resin). . Furthermore, the blade may have a high hardness coating such as titanium oxide, titanium nitride (TiN), tungsten carbide, etc. on the metal or ceramic blade body from the viewpoint of increasing wear resistance.
- PTFE polytetrafluoroethylene
- PEEK polyetheretherketone
- metal such as stainless steel, aluminum, iron, cemented carbide, etc. It may be made of aluminum or ceramic.
- the blade may include a surface layer exhibiting mold rele
- the friction coefficient ⁇ 1 between the contact part of the blade with the lump and the electrode material is smaller than the friction coefficient ⁇ 2 between the electrode material and the support. It is preferable. In this way, by satisfying the relationship of friction coefficient ⁇ 1 ⁇ friction coefficient ⁇ 2, the lumps, that is, the electrode material, tend to adhere to the support side, and as a result, an electrode material film with less variation in thickness is formed. It is assumed that this will be obtained.
- the friction coefficient ⁇ 1 and the friction coefficient ⁇ 2 are determined by forming an electrode material layer from an electrode material and measuring the friction coefficient between the electrode material layer and the blade or support. Specifically, first, a cell (a cylinder with a diameter of 20 mm to 30 mm and a height of 20 mm to 30 mm) is filled with 5 g to 20 g of electrode material, and voids in the electrode material are removed (that is, air is removed). Form an electrode material layer. The obtained electrode material layer is placed on a blade or support, and a weight of 100 g to 1000 g is placed on the electrode material layer. Thereafter, the electrode material layer is caused to slide sideways on the blade or support using a tensile testing machine (sliding speed: 5 mm/sec).
- a tensile testing machine sliding speed: 5 mm/sec.
- the coefficient of friction is determined from the relational expression obtained by plotting the relationship between the vertical load due to the weight and the drag force measured by the tensile testing machine obtained during this sideslip.
- the blade or support cannot be directly applied to the above measurements, take out only the surface of the blade or support, or prepare a measurement sample with the same composition and surface properties as the surface of the blade or support, and use this. You can measure it using Note that the above measurements are performed in a dry room environment at 21° C. and 0% RH (dew point temperature -60° C.).
- the roller is a member whose outer peripheral surface can rotate, but its size, material, etc. are determined by the type of electrode material (type of electrode active material, solid component concentration, composition of electrolyte (viscosity, surface tension), etc.), It may be determined as appropriate depending on the size, thickness, etc. of the electrode material film to be formed.
- the material constituting the outer circumferential surface of the roller may be the same as that of the blade, and may have a surface layer exhibiting releasability.
- the outer diameter of the roller is not particularly limited, but may be, for example, 20 mm to 30 mm. Furthermore, since the roller rotates, the coefficient of friction between its outer peripheral surface and the lump can be considered to be zero. However, as a result, the adhesion with the lump (ie, electrode material) may increase, so it is preferable to sandwich a release paper between the lump and the outer peripheral surface of the roller.
- the specific electrode material includes at least an electrode active material and an electrolyte, and has a solid component concentration of 20% by volume to 90% by volume.
- the solid content concentration of the specific electrode material is preferably 30% to 80% by volume, more preferably 40% to 70% by volume, even more preferably 40% to 60% by volume.
- the electrode active material is a material that can insert and release ions of metal elements belonging to Group 1 or Group 2 of the periodic table.
- the electrode active material is included in the solid component. Examples of the electrode active material include a positive electrode active material and a negative 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.
- the positive electrode active material include transition metal oxides and elements that can be composited with lithium (for example, sulfur).
- the positive electrode active material is preferably a transition metal oxide.
- the transition metal oxide is at least one transition metal element selected from the group consisting of Co (cobalt), Ni (nickel), Fe (iron), Mn (manganese), Cu (copper), and V (vanadium).
- element Ma is preferably a transition metal oxide.
- the molar ratio of Li to Ma (Li/Ma) is preferably 0.3 to 2.2.
- transition metal oxides include Group 1 elements other than lithium, Group 2 elements, Al (aluminum), Ga (gallium), In (indium), Ge (germanium), Sn (tin), Pb ( At least one transition metal element (hereinafter referred to as "element Mb") selected from the group consisting of lead), Sb (antimony), Bi (bismuth), Si (silicon), P (phosphorus), and B (boron). .) may be included.
- element Mb transition metal element selected from the group consisting of lead
- Sb antimony
- Bi bismuth
- Si silicon
- P phosphorus
- B boron
- 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 phosphate compounds.
- transition metal-containing silicate compounds include transition metal-containing silicate compounds.
- transition metal oxides having a layered rock salt structure examples 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 aluminate [NCA]), LiNi 1/3 Co 1/3 Mn 1/3 O 2 (nickel manganese cobalt lithium [NMC]), and LiNi 0.5 Mn 0.5 O 2 (manganese nickel lithium oxide).
- 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 aluminate [NCA]
- LiNi 1/3 Co 1/3 Mn 1/3 O 2 nickel manganese cobalt lithium [NMC]
- LiNi 0.5 Mn 0.5 O 2 mangaganese nickel lithium oxide
- transition metal oxides having a spinel structure examples 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 .
- lithium-containing transition metal phosphate compounds include olivine-type iron phosphates (e.g., LiFePO 4 and Li 3 Fe 2 (PO 4 ) 3 ), iron pyrophosphates (e.g., LiFeP 2 O 7 ), and phosphorus.
- Acid cobalt salts eg, LiCoPO 4
- monoclinic nasicon-type vanadium phosphate salts eg, Li 3 V 2 (PO 4 ) 3 (lithium vanadium phosphate)).
- lithium-containing transition metal halogenated phosphate compounds include iron fluorophosphates (e.g., Li 2 FePO 4 F), manganese fluorophosphates (e.g., Li 2 MnPO 4 F), and phosphorus fluorides. Acid cobalt salts (eg, Li 2 CoPO 4 F) are included.
- lithium-containing transition metal silicate compound examples include Li 2 FeSiO 4 , Li 2 MnSiO 4 , and Li 2 CoSiO 4 .
- 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 oxide), Lithium aluminate [NCA]), and LiNi 1/3 Co 1/3 Mn 1/3 O 2 (lithium nickel manganese cobalt oxide [NMC]). preferable.
- LiCoO 2 lithium cobalt oxide [LCO]
- LiNi 0.85 Co 0.10 Al 0.05 O 2 nickel cobalt oxide
- NCA Lithium aluminate
- NMC lithium nickel manganese cobalt oxide
- the positive electrode active material may be a commercially available product or a synthetic product manufactured by a known method (for example, a calcination method).
- the positive electrode active material obtained by the calcination method may be washed using water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.
- the positive electrode active material may have a carbon film on its surface.
- the shape of the positive electrode active material is not limited, but from the viewpoint of ease of handling, it is preferably particulate.
- the volume average particle size of the positive electrode active material is not limited, and can be, for example, 0.1 ⁇ m to 50 ⁇ m.
- the volume average particle diameter of the positive electrode active material is preferably 0.3 ⁇ m to 40 ⁇ m, more preferably 0.5 ⁇ m to 30 ⁇ m.
- the volume average particle size of the positive electrode active material is 0.3 ⁇ m or more, an aggregate of electrode materials can be easily formed, and scattering of the electrode material during handling can be suppressed.
- the volume average particle size of the positive electrode active material is 40 ⁇ m or less, the thickness of the electrode molded body can be easily adjusted, and the generation of voids can be suppressed during the molding process.
- the volume average particle diameter of the positive electrode active material is measured by the following method.
- a dispersion containing 0.1% by mass or less of the positive electrode active material is prepared by mixing the positive electrode active material and a solvent (for example, pure water, ethanol, heptane, octane, toluene, or xylene).
- a dispersion liquid irradiated with 1 kHz ultrasonic waves for 10 minutes is used as a measurement sample.
- a laser diffraction/scattering particle size distribution analyzer for example, LA-960 manufactured by Horiba, Ltd.
- data was acquired 50 times at a temperature of 25°C, and the volume average particle size was determined from the volume frequency particle size distribution. Find the diameter.
- a quartz cell is used as the measurement cell. The above measurement is performed using five samples, and the average of the measured values is taken as the volume average particle diameter of the positive electrode active material. For other detailed conditions, refer to "JIS Z 8828:2013" as necessary.
- Examples of methods for adjusting the particle size of the positive electrode active material include methods using a crusher, a crusher, and a classifier. Further, as a method for adjusting the particle size of the positive electrode active material, a known milling method may be applied.
- the manufactured electrode material may contain one type of positive electrode active material, or may contain two or more types of positive electrode active materials. Furthermore, even if the manufactured electrode material contains one type of positive electrode active material, positive electrode active materials having different particle sizes may be used in combination.
- the content of the positive electrode active material in the total volume of the electrode material to be produced is preferably 30% to 60% by volume, more preferably 35% to 55% by volume, and 40% to 50% by volume. More preferably, it is expressed in volume %.
- 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.
- negative electrode active materials include carbonaceous materials, metal oxides (e.g., tin oxide), silicon oxide, metal composite oxides, lithium alone, lithium alloys (e.g., lithium aluminum alloy), and alloys with lithium. Possible metals include, for example, Sn, Si, and In. Among the above, the negative electrode active material is preferably a carbonaceous material or a lithium composite oxide from the viewpoint of reliability.
- a carbonaceous material is a material 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 synthetic resins (e.g., polyester).
- Examples include carbonaceous materials made by firing acrylonitrile (PAN) and furfuryl alcohol resins.
- 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, glass carbon fibers, and activated carbon fibers).
- 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, glass carbon fibers, and activated carbon fibers.
- Graphite also includes, for example, mesophase microspheres, graphite whiskers, and tabular graphite.
- "flat plate shape” means a shape having two main planes facing in opposite directions.
- the metal composite oxide is preferably a metal composite oxide capable of intercalating and deintercalating lithium.
- the metal composite oxide capable of intercalating and deintercalating lithium preferably contains at least one element selected from the group consisting of titanium and lithium, from the viewpoint of high current density charge/discharge characteristics.
- the metal oxide and metal composite oxide are particularly preferably amorphous oxides.
- the metal oxide and metal composite oxide are chalcogenides.
- Chalcogenides are reaction products of metal elements and elements of group 16 in the periodic table.
- amorphous oxides of metalloid elements and chalcogenides are preferred, and elements of groups 13 to 15 in the periodic table, Al, Ga, Si, Sn , Ge, Pb, Sb, and Bi, and chalcogenide.
- the negative electrode active material further contains titanium.
- a negative electrode containing titanium has excellent rapid charging and discharging characteristics due to small volume fluctuations during intercalation and desorption of lithium ions, and from the viewpoint of suppressing electrode deterioration and extending the life of lithium ion secondary batteries.
- the electrode active material is preferably Li 4 Ti 5 O 12 (lithium titanate [LTO]).
- the negative electrode active material may be a commercially available product or a synthetic product produced by a known method (for example, a calcination method).
- the negative electrode active material obtained by the calcination method may be washed using water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.
- the negative electrode active material is available, for example, as CGB20 (Nippon Graphite Industries Co., Ltd.).
- the composition of the negative electrode active material is measured using inductively coupled plasma (ICP) emission spectrometry.
- ICP inductively coupled plasma
- the shape of the negative electrode active material is not limited, but is preferably particulate from the viewpoint of ease of handling and easy control of uniformity during mass production.
- the volume average particle diameter of the negative electrode active material is preferably 0.1 ⁇ m to 60 ⁇ m, more preferably 0.3 ⁇ m to 50 ⁇ m, and particularly preferably 0.5 ⁇ m to 40 ⁇ m.
- 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.
- Examples of methods for adjusting the particle size of the negative electrode active material include a method using a pulverizer or a classifier.
- the manufactured electrode material may contain only one type of negative electrode active material, or may contain two or more types of negative electrode active materials.
- the content of the negative electrode active material in the total volume of the electrode material to be produced is preferably 30% to 60% by volume, more preferably 35% to 57% by volume, and 45% to 55% by volume. More preferably, it is expressed in volume %.
- the surfaces of the positive electrode active material and the negative electrode active material may each be coated with a surface coating agent.
- the surface coating agent include metal oxides containing Ti, Nb, Ta, W, Zr, Si, or Li.
- the metal oxides include spinel titanate, tantalum oxides, niobium oxides, and lithium niobate compounds.
- the electrolytic solution is not particularly limited, and any known electrolytic solution can be used.
- the electrolytic solution include an electrolytic solution containing an electrolyte and a solvent.
- Specific examples of the electrolytic solution include, for example, an electrolytic solution containing a lithium salt compound as an electrolyte and a carbonate compound as a solvent.
- the lithium salt compound examples include lithium hexafluorophosphate.
- the electrolytic solution may contain one type of lithium salt compound alone, or may contain two or more types of lithium salt compounds.
- carbonate compounds include chain carbonate compounds such as ethyl methyl carbonate (also referred to as EMC), dimethyl carbonate (also referred to as DMC), and diethyl carbonate (DEC), ethylene carbonate (also referred to as EC), and propylene carbonate (PC).
- chain carbonate compounds such as ethyl methyl carbonate (also referred to as EMC), dimethyl carbonate (also referred to as DMC), and diethyl carbonate (DEC), ethylene carbonate (also referred to as EC), and propylene carbonate (PC).
- Examples include cyclic carbonate compounds such as (also referred to as).
- the electrolytic solution may contain one type of carbonate compound alone, two or more types of carbonate compounds, or a combination of one or more types of chain carbonate compounds and one or more types of cyclic carbonate compounds. You may.
- the electrolyte contained in the electrolytic solution for example, a known inorganic solid electrolyte can also be used.
- an ionic liquid may be used as a component of the electrolytic solution.
- Ionic liquids can be used either as electrolytes or as solvents.
- the content of the electrolyte in the total volume of the electrode material to be manufactured is preferably 80% by volume or less, more preferably 70% by volume or less, and even more preferably 60% by volume or less.
- the lower limit of the content of the electrolytic solution in the electrode material may be more than 0% by volume, and preferably 10% by volume or more.
- the manufactured electrode material 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 "solvent").
- 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.
- the boiling point of the solvent is preferably 50°C or higher, more preferably 70°C or higher at normal pressure (ie, 1 atm).
- 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 atm).
- the manufactured electrode material may contain one type of solvent alone, or may contain two or more types of solvents.
- the content of liquid components (i.e., electrolyte and solvent) relative to the total volume of the electrode material to be manufactured is preferably 80% by volume or less, more preferably 70% by volume or less, and 60% by volume or less. It is even more preferable that there be.
- the content of the liquid component in the electrode material is 80% by volume or less, it is possible to suppress the liquid component from seeping out when the electrode material is molded. Further, when the liquid component contains a solvent, deterioration of battery performance can be suppressed.
- the lower limit of the content of the liquid component in the electrode material may be more than 0% by volume, and preferably 10% by volume or more.
- the liquid component in the electrode material is preferably liquid even at -10°C, and is preferably liquid even at -20°C. It is preferable that there be. That is, the component in the electrode material that is liquid at 25°C is preferably a component that does not solidify at -10°C, and is preferably a component that does not solidify even at -20°C.
- the manufactured electrode material preferably contains a conductive additive from the viewpoint of improving the electronic conductivity of the electrode active material.
- the conductive aid is not limited, and any known conductive aid can be used.
- the conductive aid is included in the solid component.
- Examples of conductive aids 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), and carbon fiber (e.g., needle coke). other carbonaceous materials (e.g., graphene, and fullerenes); metal powders (e.g., copper powders, and nickel powders); metal fibers (e.g., copper fibers, and nickel powders); fibers), and conductive polymers (eg, polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives).
- 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 fiber e.g., needle coke
- the manufactured electrode material may contain one type of conductive aid, or may contain two or more types of conductive aid.
- the content of the conductive additive is 0.05% to 5% by volume based on the total volume of the electrode material, from the viewpoint of improving the electronic conductivity of the electrode active material. %, more preferably 0.1% to 4% by volume, even more preferably 0.5% to 3% by volume.
- the manufactured electrode material may contain a binder, a dispersant, other additives, etc. in addition to the above-mentioned components.
- the binder include fluorine-containing resins, hydrocarbon thermoplastic resins, acrylic resins, and urethane resins.
- the dispersant may be any known dispersant that can disperse the object to be dispersed.
- known additives added to electrode materials can be used.
- the electrode material can be prepared, for example, by mixing an electrode active material, an electrolytic solution, and other components used as necessary.
- Examples of the mixing method include methods using a ball mill, bead mill, planetary mixer, blade mixer, roll mill, kneader, or disk mill.
- the molded body for a sheet electrode obtained by the method for producing a molded body for a sheet electrode according to the present disclosure can be used as various electrodes.
- the sheet-like electrode molded body is preferably a semi-solid secondary battery electrode molded body.
- the average thickness of the sheet-like electrode molded body is preferably 0.01 mm to 2 mm, and preferably 0.05 mm to 1.5 mm, from the viewpoint of improving battery performance (for example, discharge capacity and output characteristics). is more preferable, and particularly preferably 0.1 mm to 1 mm.
- the average thickness of the electrode molded body is measured in the same manner as the average thickness of the support.
- Electrolyte X1 64 g was added to kneaded material Y1 (176 g), and stirred at 1500 rpm for 120 seconds using a mixer (Awatori Rentaro ARE-310, manufactured by Shinky Co., Ltd.) to form a positive electrode material. (P1) was obtained. The volume ratio of the solid component to the liquid component of the obtained positive electrode material (P1) was 48:52.
- Blade (B1) stainless steel blade
- Example 1 The previously prepared lumps (P1) were dispersed and supplied onto the continuously conveyed support (S1), and a plurality of lumps were dispersed and arranged on the support (Step A).
- the plurality of lumps distributed and arranged on the support have an average height of 3 mm, a diameter of 3 mm to 5 mm, and a distance between the area centers of gravity of adjacent lumps (distance D) of 10 mm, The area ratio was 15%.
- the blade 30 was arranged so that the distance C between the surface of the support 10 and the tip of the blade 30 was 0.3 mm. Then, as shown in FIGS.
- the support 10 is conveyed and moved in the direction of the arrow X, and the plurality of lumps 20 distributed on the support 10 are brought into contact with the blade 30 and It passed through a gap with C.
- the electrode material film 24, which was a continuous film was formed on the support 10 along the transport direction (arrow X direction) of the support 10.
- the thickness of the obtained electrode material film 24 was 0.3 mm.
- the ratio (H/C) was 10.
- the ratio (Y/X) satisfied 1 ⁇ Y/X ⁇ 5 on a volume basis.
- the pressure applied to the electrode material (lump (P1)) from the blade, which is a molded member was 100 kPa.
- a hopper as shown in FIG. 2 of JP-A-2021-027043 was prepared. This hopper had a nozzle with an opening width of 200 mm and an opening height of 1 mm for discharging the electrode material.
- the electrode material for a positive electrode (P1) was placed in this hopper, and the electrode material for a positive electrode (P1) was discharged from a nozzle onto the support that was being transported and moved. As a result, an electrode material film having a thickness of 1 mm was formed on the support.
- the pressure applied to the electrode material during discharge from the nozzle was 10,000 kPa.
- the pressure applied to the electrode material (lump) from the molded member in Example 1 is 100 times or more the pressure applied to the electrode material in Comparative Example 1. From this, it can be seen that in the method for manufacturing a sheet-like electrode molded body according to the present disclosure, a sheet-like electrode molded body having a desired thickness can be manufactured while reducing the load applied to the electrode material.
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Abstract
Description
半固体電池に適用される電極は、例えば、粉体である電極活物質と電解液とを少なくとも含む電極材料を用いて製造される。
特開2021-027043号公報には、連続するシート状の基材の表面に、電極活物質を含む電極組成物からなる電極組成物層が配置された電極組成物層配置部が間欠的に配置されたリチウムイオン電池用電極材の製造方法であって、上記基材上に上記電極組成物を連続的に供給する供給工程と、上記供給工程によって上記基材上に供給された上記電極組成物を加圧して上記電極組成物層を得る加圧工程と、上記供給工程によって上記基材上に供給された上記電極組成物の一部を除去して、上記基材上に電極組成物層配置部を形成する除去工程と、を備えるリチウムイオン電池用電極材の製造方法が開示されている。
このような電極材料を上記(1)の方法に適用する場合、電極材料を細長い矩形の吐出口から強い圧力(荷重)をかけて押し出す必要がある。そのため、電極材料を吐出させるための装置には、大きな負荷がかかる。
一方、粘土様の性状を有する電極材料を上記(2)の方法に適用する場合には、上記(1)の方法とは異なり、電極材料を細長い矩形の吐出口から強い圧力をかけて押し出す必要はない。しかしながら、(2)の方法では、押し出された電極材料の厚みを、ブレード等の成形部材で余剰分を削ぎ取る、又は、プレス機にて押圧し、更に余剰分を支持体外に排出することで調整するが、電極材料が粘土様の性状を有することから、成形部材又はプレス機により電極材料を変形等させる際に、大きな荷重が必要となる。
つまり、上述のように、上記(1)の方法及び(2)の方法では、電極材料に対して、大きな荷重をかける過程が含まれてしまう。電極材料に大きな荷重をかけるためには、電極材料を保持する装置又は部材を大型化かつ堅牢化せざるを得ない。また、大きな荷重がかかることで、電極材料の固体成分と液体成分とが分離してしまい、目的とする厚みの電極材料膜を形成しにくくなることもある。
本開示の一実施形態は、電極材料にかかる荷重を低減し、且つ、目的とする厚みのシート状電極用成形体を製造しうる、シート状電極用成形体の製造方法を提供することを課題とする。
<1> 電極活物質と電解液とを含み且つ固体成分濃度が20体積%~90体積%である電極材料の複数の塊状物を、支持体上に分散して配置させる工程Aと、
支持体上に分散して配置された複数の塊状物を成形部材により合一し、支持体上に電極材料膜を形成する工程Bと、
を含む、シート状電極用成形体の製造方法。
<2> 成形部材を、支持体表面から一定の距離を保ったまま、支持体表面に沿って相対移動させることで、支持体上に分散して配置された複数の塊状物を合一し、支持体上に電極材料膜を形成する、<1>に記載の、シート状電極用成形体の製造方法。
<3> 支持体上に分散して配置された複数の塊状物の平均高さをHとし、成形部材と支持体表面との距離をCとしたとき、距離Cに対する高さHの比(H/C)が、1<H/C≦100を満たす、<2>に記載のシート状電極用成形体の製造方法。
<4> 成形部材から電極材料(塊状物)に印加される圧力が10kPa~500kPaである、<1>~<3>のいずれか1つに記載のシート状電極用成形体の製造方法。
<5> 支持体上に分散して配置された複数の塊状物において、隣接する塊状物の面積重心間距離が0.1mm~50mmである、<1>~<4>のいずれか1つに記載のシート状電極用成形体の製造方法。
<6> 支持体上に分散して配置された複数の塊状物が占める領域が、支持体上における電極材料膜の形成領域に対し、10%~90%である、<1>~<5>のいずれか1つに記載のシート状電極用成形体の製造方法。
<7> 工程Aを、電極活物質と電解液とを含み且つ固体成分濃度が20体積%~90体積%である電極材料の複数の塊状物を、支持体上に散布供給することで行う、<1>~<6>に記載のシート状電極用成形体の製造方法。
<8> 工程A及び工程Bを連続搬送されている支持体を用いて行い、工程Bにて支持体の搬送方向に沿って連続膜である電極材料膜を形成する、<1>~<7>のいずれか1つに記載のシート状電極用成形体の製造方法。
<9> 成形部材と支持体表面との距離と同じ厚さで且つ隙間のない電極材料膜を形成しうる理論上の電極材料の量をXとし、支持体上への電極材料の塊状物の供給量をYとしたとき、量Xに対する供給量Yの比(Y/X)が体積基準にて1≦Y/X≦5を満たす、<7>又は<8>に記載のシート状電極用成形体の製造方法。
本開示において、「工程」との用語には、独立した工程だけでなく、他の工程と明確に区別できない場合であっても工程の所期の目的が達成されれば、本用語に含まれる。
本開示において、「(メタ)アクリル」とは、アクリル及びメタクリルの双方、又は、いずれか一方を意味する。
本開示において、組成物中の各成分の量は、組成物中に各成分に該当する物質が複数存在する場合、特に断らない限り、組成物中に存在する複数の物質の合計量を意味する。
本開示において、2以上の好ましい態様又は形態の組み合わせは、より好ましい態様又は形態である。
本開示において、「固体成分」とは、25℃、1気圧下において固体状である成分を意味し、「液体成分」とは、25℃、1気圧下において液体状である成分を意味する。
また、本開示において、支持体における「幅方向」とは、長手方向に直交する方向を指し、長尺の支持体であれば、長尺方向に直交する方向を指す。
更に、成膜部材(例えば、ブレード)における「幅方向」とは、成膜部材が支持体表面に沿って相対移動する方向(即ち、支持体上における電極材料膜の形成方向)に直交する方向を指す。つまり、ブレードにおける「幅方向」は、電極材料膜の「幅方向」にも該当する。
本開示に係るシート状電極用成形体の製造方法は、電極活物質と電解液とを含み且つ固体成分濃度が20体積%~90体積%である電極材料の複数の塊状物を、支持体上に分散して配置させる工程Aと、支持体上に分散して配置された複数の塊状物を成形部材により合一し、支持体上に電極材料膜を形成する工程Bと、を含む。
以下、「電極活物質と電解液とを含み且つ固体成分濃度が20体積%~90体積%である電極材料」を、「特定電極材料」ともいい、「シート状電極用成形体」を、単に、「電極用成形体」ともいう。
検討の結果、まず、支持体上に、粘土様の性状を呈する電極材料の複数の塊状物を分散して配置させ、その後、分散して配置された複数の塊状物を成形部材により合一させて電極材料膜を形成する手法を見出した。この手法によれば、成形部材と塊状物との接触面積が小さく、成形部材から電極材料にかかる荷重が小さくて済むものと考えられる。また、複数の塊状物を合一させる際、成形部材の調整により目的とする厚みの電極材料膜を形成することができる。
これらの結果、本開示に係る電極用成形体の製造方法では、電極材料にかかる荷重を低減しつつも、目的とする厚みのシート状電極用成形体が製造される。
また、特開2021-027043号公報には、支持体上に分散して配置された複数の塊状物を成形部材により合一し、支持体上に電極材料膜を形成することは記載されていない。
工程Aでは、電極活物質と電解液とを含み且つ固体成分濃度が20体積%~90体積%である電極材料(すなわち、特定電極材料)の複数の塊状物を、支持体上に分散して配置させる。
本開示において、「電極材料の塊状物」とは、径が0.1mm~20mmである粒状物(ペレットともいう)、又はその二次粒子(すなわち、凝集体)を指す。ここで、径が0.1mm~20mmである粒状物は、少なくとも電極活物質と電解液とを含む混合物からなる粒子である。
塊状物について、図1を用いて説明する。ここで、図1は、塊状物の形態の一例を示す概略図である。
図1に示すように、塊状物20は、例えば、粒状物22が3つ凝集してなる凝集体である。塊状物20に含まれる粒状物22の数は、特に限定されない。
ここで、粒状物の径の測定には、円相当径を求める公知の方法が用いられる。すなわち、粒状物の径は、粒状物の円相当径であることを意味する。
また、粒状物の形状としては、特に制限されず、球形状、楕円体状、円柱状、平板状、不定形状等であってもよい。
支持体上に分散して配置された塊状物の径としては、例えば、0.1mm~20mmであることが好ましく、0.5mm~10mmであることがより好ましく、1mm~5mmであることが更に好ましい。
塊状物の径の測定には、円相当径を求める公知の方法が用いられる。すなわち、塊状物の径は、塊状物の円相当径であることを意味する。
塊状物の高さは、図2における「H」に該当する。塊状物の高さは、支持体を基準としたレーザー変位計による測定にて求められる。なお、測定は、支持体上における電極材料膜の形成領域上に存在する全塊状物を100個数%としたとき、そのうち無作為に選択した50個数%(小数点以下切り捨て)に該当する個数の塊状物について行い、得られた測定値の算術平均値を「塊状物の平均高さ」とする。
隣接する塊状物の面積重心間距離は、図3における「D」に該当する。隣接する塊状物の面積重心間距離は、塊状物が分散している状態の支持体を上面から視たときの画像を得て、この画像において、1つの塊状物(基準塊状物)を特定し、その粒状物に最も近い隣接する塊状物(近接塊状物)を選定し、それら隣接する塊状物の面積重心(図3中の20C)間の距離を測定することで求められる。なお、上記基準塊状物としては、支持体上における電極材料膜の形成領域上に存在する全塊状物を100個数%としたとき、そのうち25個数%(小数点以下切り捨て)に該当する個数の塊状物を選択する。この基準塊状物の選択の際、1度選択された基準塊状物とその近接塊状物は除くものとする。得られた測定値の算術平均値を「隣接する塊状物の面積重心間距離」とする。
また、連続搬送されている支持体上に、支持体の搬送方向に沿って、連続的に電極材料膜を形成する態様の場合は、支持体を上面から視たときの画像として、支持体の幅方向に沿って設けられたラインセンサカメラにより得られる1ラインの画像をつなぎ合わせて得られる二次元画像を用いればよい。
ここで、支持体上における電極材料膜の形成領域とは、支持体の全表面積のうち、電極材料の塊状物を合一することで電極材料膜を形成する領域を指し、支持体上における電極材料膜で覆われる領域に該当する。なお、支持体が、集電体、又は集電体と樹脂フィルムとの積層体であれば、集電体の面積が電極材料膜の形成領域となる。
塊状物の面積率は、以下のようにして求める。
即ち、まず、塊状物が分散している状態の支持体を上面から視たときの画像を得て、この画像を二値化処理し、支持体上の塊状物が占める面積を算出する。そして、算出された塊状物が占める面積を、式:塊状物が占める面積/支持体上における電極材料膜の形成領域×100に導入することで求められる。
また、連続搬送されている支持体上に、支持体の搬送方向に沿って、連続的に電極材料膜を形成する態様の場合は、支持体を上面から視たときの画像として、隣接する塊状物の面積重心間距離を求める際と同様に、ラインセンサカメラを用いて得られる二次元画像を用いればよい。
即ち、工程Aは、特定電極材料の複数の塊状物を、支持体上に散布供給することで行うことが好ましい。つまり、予め作製しておいた特定電極材料の複数の塊状物を、支持体上に散布供給することで、特定電極材料の複数の塊状物を支持体上に分散して配置させることができる。
造粒手段としては、押出造粒法、粉砕造粒法、圧縮造粒法、湿式(凝集)造粒法、ダイサーを用いた造粒法等が挙げられる。
造粒手段により得られた塊状物は、公知の搬送手段、及び供給手段により、支持体上に散布供給される。
また、散布供給は、供給手段を支持体表面に沿って相対移動させることで、行うことができる。
工程Aにて用いる特定電極材料の詳細については、後述する。
工程Bでは、支持体上に分散して配置された複数の塊状物を成形部材により合一し、支持体上に電極材料膜を形成する。
特に、工程Bでは、成形部材を、支持体表面から一定の距離を保ったまま、支持体表面に沿って相対移動させることで、支持体上に分散して配置された複数の塊状物を合一し、支持体上に電極材料膜を形成することが好ましい。
図4に示すように、ブレード(成形部材の一例)30は、支持体10表面から一定の距離を保つように設置されている。以下、適宜、ブレード30の先端部(具体的には、ブレード30の支持体10表面に最も近い角部)と支持体10表面との距離を、「距離C」ともいう。言い換えれば、支持体10表面とブレード30の先端部との間には、距離Cを有する空隙が形成されていることとなる。
また、距離Cを有する空隙を、支持体10上に分散して配置された塊状物20が通過することで、塊状物20に荷重がかかり厚みが規制され、距離Cと同等の厚みの電極材料膜24が形成される。
また、支持体表面とブレードの先端部との距離(即ち、空隙の高さ)は、その幅方向で多少の分布が存在することがあるが、この分布が3%以内又は20μm以内であれば、これを許容する。
なお、ブレードを振動させるための加振器としては、ブレードの少なくとも塊状物との接触部を振動させることができれば特に制限はなく、例えば、空気式バイブレーター、モーター型バイブレーター、ピエゾ振動子、超音波振動器等が挙げられる。
本開示に係る電極用成形体の製造方法では、支持体表面とブレードとが相対移動すればよく、上記の態様の他、固定した支持体に対してブレードを一方向に移動させる態様であってもよいし、支持体とブレードとの両方をそれぞれ一方向に移動させる態様であってもよい。
但し、電極材料膜を連続的に形成するためには、すなわち、連続膜である電極材料膜を形成するためには、長尺の支持体を用い、固定したブレードに対し、長尺の支持体を搬送移動させる態様が好ましい。
成形部材としては、ブレードの他、ローラが挙げられる。成形部材がローラである場合、ローラは、ブレードと同様に、支持体表面から一定の距離を保つように設置されればよ
い。ローラは、支持体上に分散して配置された複数の塊状物に接触しながら回転し、支持体上に塊状物を延ばすことができる。その結果、支持体上に延ばされた複数の塊状物が互いに合一し、電極材料膜が形成される。
工程Bにおいては、塊状物の合一が容易になる観点から、支持体上に分散して配置された複数の塊状物の平均高さをHとし、成形部材と支持体表面との距離をC(既述の距離Cに該当)としたとき、距離Cに対する高さHの比(H/C)が、1<H/C≦100を満たすことが好ましく、1<H/C≦50を満たすことがより好ましく、1<H/C≦10を満たすことがさらに好ましい。
ここで、距離Cは、ブレードが支持体に接触した高さを基準としたときのレーザー変位計による測定で求められる。また、距離Cは、メカニカルゲージにより測定してもよい。
工程Bにおいては、塊状物が成形部材に接触する際に、成形部材から塊状物、すなわち、特定電極材料に圧力が印加される。このとき、成形部材に接触している塊状物、すなわち、特定電極材料に印加される圧力は10kPa~500kPaであることが好ましく、10kPa~100kPaであることがより好ましく、10kPa~20kPaであることが更に好ましい。
ここで、電極材料に印加される圧力は、以下の方法で求められる。
即ち、成形部材を、アクチュエータ(エアシリンダー、モーター駆動のリニアアクチュエータ、ピエゾなど)を用いて、支持体上に分散して配置された塊状物(すなわち電極材料)に対して一定の力で押し付け、更に、成形部材を支持体表面に沿って相対移動させ、目的とする厚さの電極材料膜を形成するときの、アクチュエータによる力を電極材料の受圧面積で割ることで求められる。
本開示に係る電極用成形体の製造方法は、工程A及び工程Bを連続搬送されている支持体を用いて行い、工程Bにて支持体の搬送方向に沿って連続膜である電極材料膜を形成することが好ましい。また、工程Aを、特定電極材料の複数の塊状物を、連続搬送されている支持体上に散布供給することで行うことが好ましい。
この好ましい態様では、連続搬送されている支持体上に、支持体の搬送方向に沿って、連続的に電極材料膜を形成する態様である。
この態様を採用することで、電極材料膜が生産性よく形成することができる。
なお、支持体の搬送方向に沿って、連続的に電極材料膜を形成する態様においては、比(Y/X)の値を、上記の範囲内において、適宜、調整してもよい。
ここで、比(Y/X)の値は、供給量Yを変えることで調整することができる。供給量Yは、工程Aが行われている間、同じであってもよいし、異なってもよい。
また、供給量Y[mm3/秒]は、電極材料を供給する供給手段(例えば、ポンプ、フィーダー等)の流量から求められる。
本開示に係る電極用成形体の製造方法は、その他の工程を含んでいてもよい。
その他の工程としては、例えば、電極材料膜を加圧する工程、支持体が離型紙である場合、離型紙上に形成された電極材料膜を集電体へと転写する工程等が挙げられる。
本開示に係る電極用成形体の製造方法は、工程Bで得られた電極材料膜を加圧する工程を有していてもよい。
本開示に係る電極用成形体の製造方法が加圧工程を含むことで、電極材料の密度を高め且つ密度、厚みの面内均一化を図ることができる。
例えば、ロール間の隙間を段階的に狭く調整した、複数の加圧ロール対を用いることで、電極材料膜を段階的に加圧できる。
本開示において、「加圧手段と電極材料膜とを相対移動させる」とは、電極材料膜に対して加圧手段を一方向に移動させること、加圧手段に対して電極材料膜を一方向に移動させること、及び加圧手段と電極材料膜とをそれぞれ一方向に移動させることを含むが、加圧手段に対して電極材料膜を一方向に移動させることが好ましい。
本工程で用いる支持体は、表面に電極材料膜を形成し得る支持体であれば、特に制限はない。特に、連続的に電極材料膜を形成する観点からは、長尺の支持体を用いることが好ましい。長尺の支持体の場合、その幅は、電極材料膜の大きさ、成形部材(例えば、ブレード)の幅方向中央部の幅(長さ)に応じて決定されればよい。
支持体の一例である集電体としては、特に制限されず、公知の集電体(正極集電体及び負極集電体)を利用できる。
支持体の一例である離型材としては、例えば、離型紙(例えば、リンテック株式会社製の剥離紙)、離型層を有するフィルム、及び離型層を有する紙が挙げられ、中でも、離型紙が好ましい。
なお、支持体として離型材を用いる場合、離型材上に形成された電極材料膜は、離型材が有する離型性を利用して、集電体へと転写させることができる。
平均厚みは、柔軟性、及び軽量性の観点から、100μm以下であることが好ましく、70μm以下であることがより好ましく、50μm以下であることが特に好ましい。
支持体の平均厚みは、断面観察によって測定される3か所の厚みの算術平均とする。断面観察においては、公知の顕微鏡(例えば、走査型電子顕微鏡)を用いることができる。
支持体の搬送機構としては、例えば、ベルトコンベア、リニアモーションガイド、クロスローラーテーブル等を使用することができる。
成形部材としては、ブレード、及びローラが挙げられる。中でも、塊状物の合一を効果的に行う観点から、ブレードが好ましい。
ブレードは、板状形状を有する部材であるが、塊状物に接触する接触部の形状、大きさ、材質等に関しては、電極材料の種類(電極活物質の種類、固体成分濃度、電解液の組成(粘度、表面張力)等)、形成する電極材料膜の大きさ、厚み等に応じて、適宜、決定されればよい。
また、ブレードの塊状物との接触部は、電極材料が付着しにくいことが好ましく、例えば、ブレードの少なくとも表面は離型性を示すことが好ましい。
例えば、ブレードとしては、ポリテトラフルオロエチレン(PTFE)等のフッ素系樹脂、ポリエーテルエーテルケトン(PEEK)等の樹脂製であってもよいし、ステンレス鋼、アルミニウム、鉄、超硬合金等の金属製であってもよいし、セラミック製であってもよい。
また、表面に離型性を付与するため、ブレードは、離型性を示す表面層(例えば、フッ素系樹脂を含む表面層、シリコン系の粒子及び樹脂を含む表面層)を備えていてもよい。
更に、ブレードは、耐摩耗性を高める観点から、金属製又はセラミック製のブレード本体に、酸化チタン、窒化チタン(TiN)、タングステンカーバイト等の高硬度被膜を有していてもよい。
このように、上記摩擦係数μ1<上記摩擦係数μ2の関係を満たすことで、塊状物、すなわち、電極材料が支持体側に付着しやすくなり、その結果として、厚みのバラツキのより少ない電極材料膜が得られるものと推測される。
具体的には、まず、セル(サイズ:直径20mm~30mm、高さ20mm~30mmの円筒)に電極材料を5g~20g充填し、電極材料中の空隙除去(即ち、空気除去)をして、電極材料層を形成する。
得られた電極材料層を、ブレード又は支持体に載せ、更に、電極材料層上に100g~1000gの重りを載せる。その後、引張試験機により、電極材料層をブレード又は支持体上で横滑りさせる(横滑り速度:5mm/sec)。この横滑りにて得られた、重りによる鉛直方向の荷重と引張試験機により測定される抗力の関係をプロットして得られた関係式から、摩擦係数を求める。
なお、ブレード又は支持体が上記測定にそのまま適用できない場合、ブレード又は支持体の表面のみを取り出す、又は、ブレード又は支持体の表面と同様の組成及び表面性状を有する測定試料を作製し、これを用いて測定すればよい。
なお、上記測定は、21℃、0%RH(露点温度-60℃)のドライルームの環境下で行われる。
ローラは、外周面が回転可能な部材であるが、大きさ、材質等に関しては、電極材料の種類(電極活物質の種類、固体成分濃度、電解液の組成(粘度、表面張力)等)、形成する電極材料膜の大きさ、厚み等に応じて、適宜、決定されればよい。
ローラの外周面を構成する材質としては、ブレードと同様であればよく、離型性を示す表面層を有していてもよい。
ローラの外径としては、特に制限はないが、例えば、20mm~30mmであればよい。
また、ローラは回転することから、その外周面と塊状物との摩擦係数を0とみなすことができる。但し、その結果として、塊状物(すなわち電極材料)との密着性が高まる場合があることから、塊状物とローラの外周面との間には離型紙を挟むことが好ましい。
以下、特定電極材料の詳細について、説明する。
特定電極材料は、電極活物質と電解液とを少なくとも含み、且つ、固体成分濃度が20体積%~90体積%である。特定電極材料の固形分濃度は、30体積%~80体積%が好ましく、40体積%~70体積%がより好ましく、40体積%~60体積%が更に好ましい。
電極活物質は、周期律表における第1族又は第2族に属する金属元素のイオンを挿入、及び放出することが可能な物質である。電極活物質は、固体成分に含まれる。
電極活物質としては、例えば、正極電極活物質及び負極電極活物質が挙げられる。
正極電極活物質としては、制限されず、正極に用いられる公知の電極活物質を利用できる。正極電極活物質としては、可逆的にリチウムイオンを挿入及び放出できる正極電極活物質であることが好ましい。
また、正極電極活物質は、その表面にカーボン被膜を有していてもよい。
正極電極活物質の体積平均粒径が0.3μm以上であることで、電極材料の集合体を容易に形成することができ、また、取り扱いの際に電極材料が飛散することを抑制できる。正極電極活物質の体積平均粒径が40μm以下であることで、電極用成形体の厚みを容易に調節することができ、また、成形過程において空隙の発生を抑制することができる。
正極電極活物質と溶媒(例えば、純水、エタノール、ヘプタン、オクタン、トルエン、又はキシレン)とを混合することによって、0.1質量%以下の正極電極活物質を含む分散液を調製する。1kHzの超音波を10分間照射した分散液を測定試料とする。レーザー回折/散乱式粒度分布測定装置(例えば、(株)堀場製作所製のLA-960)を用いて、温度25℃の条件下でデータの取り込みを50回行い、体積頻度粒度分布から体積平均粒径を求める。測定用のセルには、石英セルを用いる。上記測定を5つの試料を用いて行い、測定値の平均を正極活物質の体積平均粒径とする。その他の詳細な条件については、必要に応じて、「JIS Z 8828:2013」を参照する。
また、製造される電極材料が1種の正極電極活物質を含む場合であっても、粒径の異なる正極電極活物質を組み合わせて使用してもよい。
負極電極活物質としては、制限されず、負極に用いられる公知の電極活物質を利用できる。負極電極活物質は、可逆的にリチウムイオンを挿入及び放出できる負極電極活物質であることが好ましい。
炭素質材料としては、例えば、石油ピッチ、カーボンブラック(例えば、アセチレンブラック)、黒鉛(例えば、天然黒鉛、及び人造黒鉛(例えば、気相成長黒鉛))、ハードカーボン、及び合成樹脂(例えば、ポリアクリロニトリル(PAN)、及びフルフリルアルコール樹脂)を焼成してなる炭素質材料が挙げられる。炭素質材料としては、例えば、炭素繊維(例えば、ポリアクリロニトリル系炭素繊維、セルロース系炭素繊維、ピッチ系炭素繊維、気相成長炭素繊維、脱水PVA(ポリビニルアルコール)系炭素繊維、リグニン炭素繊維、ガラス状炭素繊維、及び活性炭素繊維)も挙げられる。黒鉛としては、例えば、メソフェーズ微小球体、グラファイトウィスカー、及び平板状の黒鉛も挙げられる。
本開示において、「平板状」とは、反対方向を向く2つの主平面を有する形状を意味する。
リチウムを吸蔵及び放出可能な金属複合酸化物は、高電流密度充放電特性の観点から、チタン及びリチウムからなる群より選択される少なくとも1種の元素を含むことが好ましい。
負極電極活物質の体積平均粒径は、上記正極電極活物質の体積平均粒径の測定方法に準ずる方法により測定する。
電解液としては、特に制限されず、公知の電解液を利用できる。電解液としては、例えば、電解質と、溶剤と、を含む電解液が挙げられる。具体的な電解液としては、例えば、電解質としてリチウム塩化合物と、溶剤としてカーボネート化合物と、を含む電解液が挙げられる。
電極材料における電解液の含有率の下限は、0体積%超であればよく、10体積%以上であることが好ましい。
溶剤としては、例えば、アルコール化合物溶剤、エーテル化合物溶剤、アミド化合物溶剤、アミノ化合物溶剤、ケトン化合物溶剤、芳香族化合物溶剤、脂肪族化合物溶剤、及びニトリル化合物溶剤が挙げられる。
電極材料における液体成分の含有量が80体積%以下であることで、電極材料を成形した際に液体成分が滲み出ることを抑制することができる。また、液体成分が溶剤を含む場合には、電池性能の劣化を抑制することができる。
電極材料における液体成分の含有率の下限は、0体積%超であればよく、10体積%以上であることが好ましい。
製造される電極材料は、電極活物質の電子伝導性の向上という観点から、導電助剤を含むことが好ましい。導電助剤としては、制限されず、公知の導電助剤を利用できる。
導電助剤は、固体成分に含まれる。
製造される電極材料は、上述成分の他、バインダ、分散剤、その他の添加剤等を含んでいてもよい。
バインダとしては、例えば、含フッ素樹脂、炭化水素系熱可塑性樹脂、アクリル樹脂、及びウレタン樹脂が挙げられる。
また、分散剤としては、分散対象物を分散しうる公知の分散剤であればよい。
更に、その他の添加剤としては、電極材料に添加される公知の添加剤を利用することができる。
電極材料は、例えば、電極活物質と、電解液と、必要に応じて用いるその他の成分と、を混合することによって調製できる。
混合方法としては、例えば、ボールミル、ビーズミル、プラネタリミキサー、ブレードミキサー、ロールミル、ニーダー、又はディスクミルを用いる方法が挙げられる。
本開示に係るシート状電極用成形体の製造方法によって得られるシート電極用成形体は、種々の電極として用いることができる。
シート状電極用成形体は、半固体二次電池の電極用成形体であることが好ましい。
電極用成形体の平均厚みは、支持体の平均厚みと同様の方法で測定される。
(1)炭酸エチレン(EC)と、炭酸プロピレン(PC)と、炭酸ジエチル(DEC)と、を混合した混合液に、LiPF6(電解質)を混合した後に、更に、ビニレンカーボネート(VC)を混合した。得られた混合液のうち、64gを取り出し、これを電解液X1とした。
(2)導電助剤(ケッチェンブラック)2gと、正極電極活物質(リン酸鉄リチウム)174gと、をミキサー(あわとり練太郎ARE-310、(株)シンキー製)にて、1500rpm(revolutions per minute、以下同じ)で30秒撹拌し、混練物Y1(176g)を調製した。
(3)混練物Y1(176g)に電解液X1(64g)を加え、ミキサー(あわとり練太郎ARE-310、(株)シンキー製)にて、1500rpmで120秒撹拌して、正極用電極材料(P1)を得た。
得られた正極用電極材料(P1)の固体成分と液体成分との体積比率は48:52であった。
支持体(S1):正極集電体(アルミニウム箔)
ブレード(B1):ステンレス鋼製のブレード
連続搬送されている支持体(S1)上に、予め作製しておいた塊状物(P1)を散布供給し、支持体上に複数の塊状物を分散して配置した(工程A)。
支持体上に分散して配置された複数の塊状物は、平均高さは3mmであり、径は3mm~5mmであり、隣接する塊状物の面積重心間距離(距離D)が10mmであり、面積率が15%であった。
図4及び図5に示すように、支持体10表面とブレード30の先端との距離Cを0.3mmとするようにブレード30を配置した。そして、図4及び図5に示すように、支持体10を矢印X方向に搬送移動させ、支持体10上に分散して配置された複数の塊状物20を、ブレード30に接触させて、距離Cを有する空隙を通過させた。これにより、支持体10上には、支持体10の搬送方向(矢印X方向)に沿って、連続膜である電極材料膜24を形成した。得られた電極材料膜24の膜厚は0.3mmであった。
なお、上記のように、比(H/C)は10であった。また、連続膜である電極材料膜を形成している際、比(Y/X)は体積基準にて1≦Y/X≦5を満たしていた。
実施例1において、成形部材であるブレードから電極材料(塊状物(P1))に印加される圧力は100kPaであった。
特開2021-027043号公報の図2に示すようなホッパーを用意した。このホッパーは、電極材料を吐出するための、開口幅200mm、開口高さ1mmのノズルを有していた。このホッパーに正極用電極材料(P1)を入れ、搬送移動させている支持体上に、ノズルから正極用電極材料(P1)を吐出させた。これにより、支持体上に、膜厚1mmの電極材料膜を形成した。
比較例1にて、ノズルから吐出させるときに電極材料に印加される圧力は10,000kPaであった。
このことから、本開示に係るシート状電極用成形体の製造方法では、電極材料にかかる荷重を低減しつつも、目的とする厚みのシート状電極用成形体を製造することができることが分かる。
10:支持体
20:塊状物
20C:面積重心
22:粒状物
24:電極材料膜
30:ブレード
C:ブレードと支持体表面との距離
D:隣接する塊状物の面積重心間距離
H:塊状物の高さ
X:支持体の搬送方向
Claims (9)
- 電極活物質と電解液とを含み且つ固体成分濃度が20体積%~90体積%である電極材料の複数の塊状物を、支持体上に分散して配置させる工程Aと、
支持体上に分散して配置された複数の塊状物を成形部材により合一し、支持体上に電極材料膜を形成する工程Bと、
を含む、シート状電極用成形体の製造方法。 - 成形部材を、支持体表面から一定の距離を保ったまま、支持体表面に沿って相対移動させることで、支持体上に分散して配置された複数の塊状物を合一し、支持体上に電極材料膜を形成する、請求項1に記載の、シート状電極用成形体の製造方法。
- 支持体上に分散して配置された複数の塊状物の平均高さをHとし、成形部材と支持体表面との距離をCとしたとき、距離Cに対する高さHの比(H/C)が、1<H/C≦100を満たす、請求項2に記載のシート状電極用成形体の製造方法。
- 成形部材から電極材料に印加される圧力が10kPa~500kPaである、請求項1又は請求項2に記載のシート状電極用成形体の製造方法。
- 支持体上に分散して配置された複数の塊状物において、隣接する塊状物の面積重心間距離が0.1mm~50mmである、請求項1又は請求項2に記載のシート状電極用成形体の製造方法。
- 支持体上に分散して配置された複数の塊状物が占める領域が、支持体上における電極材料膜の形成領域に対し、10%~90%である、請求項1又は請求項2に記載のシート状電極用成形体の製造方法。
- 工程Aを、電極活物質と電解液とを含み且つ固体成分濃度が20体積%~90体積%である電極材料の複数の塊状物を、支持体上に散布供給することで行う、請求項1又は請求項2に記載のシート状電極用成形体の製造方法。
- 工程A及び工程Bを連続搬送されている支持体を用いて行い、工程Bにて支持体の搬送方向に沿って連続膜である電極材料膜を形成する、請求項1又は請求項2に記載のシート状電極用成形体の製造方法。
- 成形部材と支持体表面との距離と同じ厚さで且つ隙間のない電極材料膜を形成しうる理論上の電極材料の量をXとし、支持体上への電極材料の塊状物の供給量をYとしたとき、量Xに対する供給量Yの比(Y/X)が体積基準にて1≦Y/X≦5を満たす、請求項7に記載のシート状電極用成形体の製造方法。
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| WO2021033520A1 (ja) * | 2019-08-19 | 2021-02-25 | 富士フイルム株式会社 | 電極用成形体の製造方法 |
| JP2022120971A (ja) | 2021-02-08 | 2022-08-19 | 株式会社Ihi | 外接ギヤポンプのギヤ軸受構造 |
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2023
- 2023-07-24 CN CN202380056459.0A patent/CN119604988A/zh active Pending
- 2023-07-24 WO PCT/JP2023/027039 patent/WO2024024735A1/ja not_active Ceased
- 2023-07-24 JP JP2024537713A patent/JPWO2024024735A1/ja active Pending
- 2023-07-24 EP EP23846465.5A patent/EP4564462A4/en active Pending
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2025
- 2025-01-27 US US19/037,291 patent/US20250174622A1/en active Pending
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| JP2014186969A (ja) | 2013-03-25 | 2014-10-02 | Toyota Motor Corp | 粉体供給装置および電極製造装置 |
| JP2017228429A (ja) * | 2016-06-22 | 2017-12-28 | トヨタ自動車株式会社 | 捲回型二次電池用電極板の製造方法 |
| JP2020129448A (ja) * | 2019-02-07 | 2020-08-27 | 日産自動車株式会社 | 電池用電極の製造方法 |
| JP2021027043A (ja) | 2019-08-06 | 2021-02-22 | 三洋化成工業株式会社 | リチウムイオン電池用電極材の製造方法及びリチウムイオン電池用電極材の製造装置 |
| WO2021033520A1 (ja) * | 2019-08-19 | 2021-02-25 | 富士フイルム株式会社 | 電極用成形体の製造方法 |
| JP2022120971A (ja) | 2021-02-08 | 2022-08-19 | 株式会社Ihi | 外接ギヤポンプのギヤ軸受構造 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2025204772A1 (ja) * | 2024-03-27 | 2025-10-02 | 富士フイルム株式会社 | 準固体電池の製造方法 |
Also Published As
| Publication number | Publication date |
|---|---|
| EP4564462A4 (en) | 2025-12-31 |
| JPWO2024024735A1 (ja) | 2024-02-01 |
| CN119604988A (zh) | 2025-03-11 |
| EP4564462A1 (en) | 2025-06-04 |
| US20250174622A1 (en) | 2025-05-29 |
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