Method for manufacturing electrode and electrode manufacturing apparatus

Abstract

A granule containing an active substance powder and a binder is prepared. The granule is supplied to the surface of a roller. The granule is charged. By rotation of the roller, the granule is transported from a first region to a second region. By forming a first electric field between the second region and a third region, the granule flies from the second region toward the third region. By forming a second electric field between the third region and a substrate, the granule flies from the third region toward the substrate.

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing electrodes and an apparatus for manufacturing electrodes. Background Technology

[0002] Japanese Patent Application Publication No. 2020-149862 discloses a method for manufacturing an electrode sheet. Summary of the Invention

[0003] An electrode comprises a substrate and an active material layer. The active material layer can be formed by coating the surface of the substrate with powder (electrode material).

[0004] A method for manufacturing electrodes using electrostatic coating has been proposed. Electrostatic coating can be used to form an active material layer with a homogeneous composition. Furthermore, to improve productivity, electrostatic coating can be performed using a roll-to-roll method.

[0005] To apply roll-to-roll electrostatic coating, a magnetic roller can be considered, for example. That is, powder is attracted to the surface of the magnetic roller by magnetic force. The substrate is supported by a support roller. An electric field is formed in the gap between the magnetic roller and the support roller. Electrostatic force acts on the powder in the electric field. The electric field strength is adjusted so that the electrostatic force prevails over the magnetic force. The powder detaches from the magnetic roller by electrostatic force. The powder flies towards the substrate. The powder adheres to the substrate. This allows the formation of an active material layer, i.e., the fabrication of electrodes. Electrodes can be continuously fabricated by the rotation of the roller.

[0006] When the electrode material is not magnetic, a magnetic carrier (magnetic particles) can be used. That is, the electrode material and magnetic particles are mixed, and the electrode material is attached to the magnetic particles. Through magnetic force, the magnetic particles are attracted to the magnetic roller. Thus, the electrode material can be supported on the magnetic roller.

[0007] However, the adhesion between the electrode material and the magnetic particles tends to be highly variable. When the adhesion is excessively strong, even with electrostatic forces, the electrode material may not detach from the magnetic particles. This can result in uneven coating.

[0008] The purpose of this disclosure is to reduce uneven coating.

[0009] The technical structure and effects of this disclosure are described below. However, the mechanisms of action described in this specification are presumptive. The mechanisms of action do not limit the technical scope of this disclosure.

[0010] 1. The method for manufacturing the electrode includes the following steps (a) to (f).

[0011] (a) Prepare particles containing active substance powder and binder.

[0012] (b) Feeding particles onto the surface of the roller.

[0013] (c) Charge the particles.

[0014] (d) The particles are transported from the first area to the second area by the rotation of the roller.

[0015] (e) By forming a first electric field between the second and third regions, the particles fly from the second region toward the third region.

[0016] (f) By forming a second electric field between the third region and the substrate, the particles fly from the third region toward the substrate.

[0017] In the vertical direction, region 2 is positioned lower than region 1. In the direction intersecting the vertical direction, region 3 is separated from region 2. In the vertical direction, the substrate is positioned lower than region 3. An active material layer is formed by the adhesion of particles to the substrate.

[0018] When transporting powder (electrode material) without relying on magnetic force, it is difficult to transport the powder in a direction that opposes gravity. This is because the powder may fall off the roller due to gravity. Therefore, when transporting powder without relying on magnetic force, in the vertical direction, the powder will be transported from a higher position to a lower position.

[0019] Figure 1 This is a conceptual diagram showing the electrode manufacturing apparatus in the first reference configuration. In the first reference configuration, powder is transported from a high position to a low position in the vertical direction (Z-axis direction). Furthermore, in the first reference configuration, electrostatic coating (powder flight) is performed vertically downwards.

[0020] In the vertical direction, the support roller 212 is adjacent to the supply roller 211. The support roller 212 is positioned lower than the supply roller 211. The supply roller 211 conveys powder 1 into the gap between the supply roller 211 and the support roller 212. The support roller 212 conveys substrate 13 into the gap between the supply roller 211 and the support roller 212. Electrostatic coating is performed in the gap between the supply roller 211 and the support roller 212. However, before the powder 1 reaches the gap between the supply roller 211 and the support roller 212, the powder 1 may fall off the supply roller 211 due to gravity. Therefore, it can be considered that uneven coating and yield loss will occur in the first reference embodiment.

[0021] Figure 2 This is a conceptual diagram showing the electrode manufacturing apparatus in the second reference configuration. In the second reference configuration, powder is also transported from a high position to a low position in the vertical direction (Z-axis direction). Furthermore, in the second reference configuration, electrostatic coating (powder flight) is performed in the horizontal direction (X-axis direction).

[0022] The supply roller 221 transports powder 1. The powder 1 is transported within a range where it is unlikely to fall due to gravity. In the horizontal direction, the support roller 222 is adjacent to the supply roller 221. Electrostatic coating is performed in the gap between the supply roller 221 and the support roller 222. However, some of the powder 1 that reaches the substrate 13 may not be able to adhere to the substrate 13 and may fall due to gravity. Therefore, it can be considered that uneven coating and yield loss will also occur in the second reference embodiment.

[0023] Figure 3 This is a conceptual diagram showing the electrode manufacturing apparatus in this embodiment. The coating material in this disclosure is particle 11. Particle 11 can be prepared by granulation of powder. Particle 11 can also be referred to as "granulated body". Ordinary powders, due to their low flowability, tend to easily cause particle agglomeration during transport. If particle agglomeration occurs, it tends to be difficult to fly even when electrostatic forces are applied. Particle 11 can have higher flowability than powder. It is expected that particle 11 can be easily flown by electrostatic forces.

[0024] In this disclosure, electrostatic coating (powder flight) is performed in two stages. A first roller 110 transports particles 11. Particles 11 are transported from a first region R1 to a second region R2. Particles 11 are transported within a range where they are unlikely to fall due to gravity. Therefore, the falling of particles 11 due to gravity before electrostatic coating can be reduced. That is, yield loss can be reduced.

[0025] Figure 4 This is a conceptual diagram illustrating the electrostatic coating in this embodiment. In a direction intersecting the vertical direction, the third region R3 separates from the second region R2. In the same direction, a first electrostatic coating is performed. That is, a first electric field E1 is formed between the second region R2 and the third region R3, and a first electrostatic force F1 acts on the particle 11. Driven by the first electrostatic force F1, the particle 11 flies from the second region R2 toward the third region R3.

[0026] Furthermore, a second electrostatic coating is performed in the vertical direction. That is, by forming a second electric field E2 between the third region R3 and the substrate 13, a second electrostatic force F2 acts on the particles 11 moving to the third region R3. Driven by the second electrostatic force F2, the particles 11 fly from the third region R3 toward the substrate 13. In addition to the second electrostatic force F2, gravity F3 also acts on the flying particles 11. This is because, in the vertical direction, the substrate 13 is at a lower position than the third region R3. With the combined force of the second electrostatic force F2 and gravity F3 acting on the flying particles 11, it is expected that the particles 11 will firmly adhere to the substrate 13. Through the synergistic effect of the above actions, it is expected that coating unevenness can be reduced in this disclosure.

[0027] 2. The particles may have a solids fraction of, for example, 70 to 100% by mass.

[0028] "Solids fraction" refers to the mass fraction of components other than the solvent relative to the total mass of the mixture. Particles are prepared by granulation of active material powder and binder. Particles can be in a dry state or a wet state. That is, particles can also contain a solvent (liquid). However, particles differ from slurries (particle dispersions). In particles, the solvent forms droplets. In particles, the solvent (liquid) is dispersed in the powder particles (solids). On the other hand, in slurries, the solvent is the dispersion medium. In slurries, the powder particles (solids) are dispersed in the solvent (liquid). Slurries can have a solids fraction of, for example, less than 60%.

[0029] Conventionally, electrodes are manufactured by coating a slurry. However, conventional methods use large amounts of solvent. This disclosure reduces the amount of solvent used. By reducing solvent usage, reductions in manufacturing costs and environmental impact can be expected.

[0030] 3. The particles may have a D50 of, for example, 100 to 200 μm.

[0031] With particles having a D50 of 100–200 μm, it is possible to expect the particles to exhibit suitable flowability, for example.

[0032] 4. The particles may have an angle of repose of, for example, less than 50°.

[0033] The angle of repose is an indicator of powder flowability. A smaller angle of repose generally indicates higher powder flowability. The angle of repose can be reduced through powder granulation. Particles with an angle of repose of less than 50° can, for example, be expected to reduce coating unevenness.

[0034] 5. The first electric field has a first electric field strength. The second electric field has a second electric field strength. For example, the second electric field strength can be lower than the first electric field strength.

[0035] The first electrostatic force can be adjusted by the first electric field strength. The second electrostatic force can be adjusted by the second electric field strength. In the second electrostatic coating, in addition to the second electrostatic force, gravity also acts on the particles. Therefore, for example, the second electric field strength can be set lower than the first electric field strength.

[0036] 6. Step (d) above may also include, for example, the step of spreading (spreading) the particles evenly on the surface of the roller.

[0037] By spreading the particles evenly on the surface of the roller, the deviation in the particle supply can be reduced. Thus, for example, it can be expected to reduce coating unevenness.

[0038] 7. The method of manufacturing the electrode may also include, for example, the following step (g).

[0039] (g) The active material layer is fixed to the substrate by applying pressure and heat to the active material layer.

[0040] Through the above step (g), for example, it is expected that the peel strength of the active material layer can be improved.

[0041] 8. The electrode manufacturing apparatus manufactures electrodes by attaching particles containing active material powder and binder to a substrate. The electrode manufacturing apparatus includes a first roller, a relay plate, a second roller, and an electric field forming device.

[0042] In a direction intersecting the vertical direction, the relay plate separates from the first roller. In the vertical direction, the second roller is positioned lower than the first roller and the relay plate. The electric field forming apparatus is configured to form a first electric field between the first roller and the relay plate, and a second electric field between the relay plate and the second roller. The first roller is configured to transport particles into the first electric field. The second roller is configured to transport a substrate into the second electric field.

[0043] In the electrode manufacturing apparatus described in 8. above, the particles can reach the substrate by flying sequentially in the first electric field and the second electric field. That is, the electrode manufacturing method described in 1. above can be performed.

[0044] 9. The electrode manufacturing apparatus may, for example, further include a third roller. The electrode manufacturing apparatus may also be configured such that the particles are spread evenly in the gap between the first roller and the third roller before the particles reach the first electric field.

[0045] The electrode manufacturing apparatus described in 9. above can perform the electrode manufacturing method described in 6. above.

[0046] The above and other objects, features, aspects and advantages of this disclosure will become apparent from the following detailed description of this disclosure, which is understood in conjunction with the accompanying drawings. Attached Figure Description

[0047] Figure 1 This is a conceptual diagram showing an electrode manufacturing apparatus in the first reference configuration.

[0048] Figure 2 This is a conceptual diagram showing the electrode manufacturing apparatus in the second reference configuration.

[0049] Figure 3 This is a conceptual diagram showing the electrode manufacturing apparatus in this embodiment.

[0050] Figure 4 This is a conceptual diagram illustrating electrostatic coating in this embodiment.

[0051] Figure 5This is a simplified flowchart of the electrode manufacturing method in this embodiment.

[0052] Figure 6 This is a conceptual diagram illustrating an example of an electrode.

[0053] Figure 7 These are photographs showing the manufacturing results of the first and second manufacturing examples. Detailed Implementation

[0054] <Definitions of terms, etc.>

[0055] The following describes the embodiments of this disclosure (which may be abbreviated as "this embodiment" in this specification) and the examples of this disclosure (which may be abbreviated as "this example" in this specification). However, this embodiment and this example do not limit the technical scope of this disclosure.

[0056] In this specification, the expressions "possessing," "comprising," "having," and variations thereof (e.g., "constructed by employing...") are open forms. Open forms may or may not include additional elements besides the essential elements. The expression "constructed by..." is a closed form. However, even in a closed form, impurities or additional elements unrelated to the present disclosure are not excluded. The expression "substantially constituted by..." is a semi-closed form. In a semi-closed form, the addition of elements that do not substantially affect the basic and novel characteristics of the present disclosure is permitted.

[0057] In this specification, expressions such as "can be carried out" and "able to be carried out" are not used in an obligatory sense meaning "must be carried out," but rather in an permissive sense meaning "has the possibility of carrying out."

[0058] In this specification, elements expressed in the singular form also include the plural form unless otherwise specified. For example, "particle" does not only mean "one particle" but can also mean "a swarm of particles".

[0059] In the methods described in this manual, the order of execution of multiple steps, actions, and operations is not limited to the order in which they are described, unless otherwise specified. For example, multiple steps can be performed simultaneously. For example, multiple steps can also be performed in reverse order.

[0060] In this specification, geometric terms (such as "parallel," "orthogonal," etc.) should not be understood in a strict sense. For example, "parallel" can deviate slightly from the strict meaning of "parallel." Geometric terms in this specification may include tolerances and errors in design, operation, manufacturing, etc. Dimensional relationships in the drawings may not always match actual dimensions. To aid in understanding the technology disclosed herein, dimensional relationships (length, width, thickness, etc.) in the drawings are sometimes altered. Furthermore, sometimes parts of the structure are omitted.

[0061] In this specification, "direction intersecting the vertical direction" refers to any direction that is not parallel to the vertical direction. Directions intersecting the vertical direction include, for example, directions orthogonal to the vertical direction (i.e., horizontal directions). Directions intersecting the vertical direction may also be orthogonal to the rotation axis of each roller.

[0062] In this specification, numerical ranges such as "70 to 100%" include both upper and lower limits unless otherwise specified. That is, "70 to 100%" represents a numerical range of "70% or more and 100% or less." Alternatively, values ​​arbitrarily selected from the numerical range can be used as new upper and lower limits. For example, new numerical ranges can be set by arbitrarily combining values ​​within the numerical range with values ​​described in other parts of this specification, tables, figures, etc.

[0063] In this specification, all numerical values ​​may be modified using the term "approximately". The term "approximately" can mean, for example, ±5%, ±3%, ±1%, etc. All numerical values ​​are approximate values ​​that can vary depending on the application of the technology disclosed herein. All numerical values ​​are expressed in significant figures. The measured value can be the average of multiple measurements. The number of measurements can be 3 or more, 5 or more, or 10 or more. The measured values, etc., can be rounded based on the number of significant figures. The measured value may include, for example, errors associated with the detection limits of the measuring device.

[0064] In this specification, "D50 of 100 μm or more" refers to the particle size in the mass (number) standard particle size distribution where the cumulative frequency from the smaller particle size side reaches 50%. The mass standard particle size distribution can be determined according to "JIS Z 8815 General Rules for Sieve Analysis".

[0065] In this specification, "D50 less than 100 μm" refers to the particle size in the volumetric particle size distribution where the cumulative frequency from the smallest particle size side reaches 50%. The volumetric particle size distribution can be determined using a laser diffraction particle size distribution measuring device.

[0066] In this manual, "angle of repose" refers to the angle formed by the inclined surface of the cone (powder mound) formed when powder particles fall naturally onto a horizontal surface and the horizontal surface. The angle of repose can be measured using the "Powder Properties Evaluation Device" manufactured by Hosokawa Mikron Co., Ltd., or an equivalent device.

[0067] In this specification, when a compound is expressed by a stoichiometric formula such as "LiCoO2", the stoichiometric formula is merely a representative example. The composition ratio can also be non-stoichiometric. For example, when lithium cobalt oxide is expressed as "LiCoO2", unless otherwise specified, lithium cobalt oxide is not limited to the composition ratio of "Li / Co / O = 1 / 1 / 2", and can contain Li, Co, and O in any composition ratio. Furthermore, doping and substitution using trace elements are also permissible.

[0068] In this specification, "melting point" refers to the peak temperature of the melting peak (endothermic peak) in the DSC (Differential Scanning Calorimetry) curve. The DSC curve can be determined according to "JIS K 7121 Method for Determination of Transition Temperature of Plastics". "Near the melting point" can indicate, for example, a range of ±20°C from the melting point.

[0069] Electrode Manufacturing Device

[0070] Figure 3 This is a conceptual diagram showing the electrode manufacturing apparatus of this embodiment. Hereinafter, "electrode manufacturing apparatus of this embodiment" can be abbreviated as "this manufacturing apparatus". This manufacturing apparatus 100 manufactures the electrode 10 by attaching particles 11 to a substrate 13.

[0071] This manufacturing apparatus 100 includes a first roller 110, a relay plate 140, a second roller 120, and an electric field forming device 150. This manufacturing apparatus 100 may also include, for example, a hopper 160, a third roller 130, etc.

[0072] This manufacturing apparatus 100 may also include, for example, a control device (not shown). The control device may also restrict the operation of each element.

[0073] The manufacturing apparatus 100 may also include, for example, a fixing device (not shown). The fixing device is capable of applying at least one of heat and pressure to the active material layer 12. The fixing device may also include, for example, a pair of heated rollers.

[0074] exist Figure 3 In this configuration, the rotation axes of each roller can be substantially parallel. The curved arrows drawn on each roller indicate the direction of rotation.

[0075] Electric field forming device

[0076] Figure 4 This is a conceptual diagram illustrating electrostatic coating in this embodiment. The electric field forming apparatus 150 includes a first power source 151 and a second power source 152. Each of the first power source 151 and the second power source 152 may include, for example, a high-voltage power supply device. The first power source 151 and the second power source 152 may, for example, be independent of each other. Alternatively, the first power source 151 and the second power source 152 may also be integrated, for example.

[0077] A first power source 151 applies a DC voltage (potential difference) between the first roller 110 and the relay plate 140. That is, the first power source 151 creates a first electric field E1 between the first roller 110 and the relay plate 140. A second power source 152 applies a DC voltage between the relay plate 140 and the second roller 120. That is, the second power source 152 creates a second electric field E2 between the relay plate 140 and the second roller 120.

[0078] In this manufacturing apparatus 100, the particles 11 fly sequentially in the first electric field E1 and the second electric field E2, and the particles 11 can reach the substrate 13. By attaching the particles 11 to the substrate 13, an active material layer 12 can be formed.

[0079] hopper

[0080] Particle 11 can be filled, for example, into hopper 160 (see reference). Figure 3 The hopper 160 includes a rotary feeder 161. The rotary feeder 161 can deliver the particles 11 at, for example, a certain flow rate.

[0081] Roller 1

[0082] The first roller 110 is conductive. The first roller 110 may be made of, for example, metal. The entire first roller 110 may be conductive, or only a portion of the first roller 110 may be conductive. For example, the portion in contact with the particle 11 may be conductive. For example, the surface layer of the first roller 110 may be conductive. The first roller 110 is electrically connected to the first power source 151.

[0083] The first roller 110 can also be referred to as a "feed roller". The first roller 110 receives particles 11 from the hopper 160 in the first region R1. The particles 11 are transported in the circumferential direction by the rotation of the first roller 110. The particles 11 are transported from the first region R1 to the second region R2.

[0084] In the vertical direction, the second region R2 is located lower than the first region R1. The second region R2 is formed in the gap between the first roller 110 and the relay plate 140. A first electric field E1 is formed between the first roller 110 and the relay plate 140. That is, the first roller 110 transports the particles 11 into the first electric field E1.

[0085] The first region R1 can be, for example, arc-shaped. For example, the "clock position" can be set with the rotation axis of the first roller 110 as the center. The 6 o'clock and 12 o'clock directions in the clock position are parallel to the vertical direction (Z-axis). The 3 o'clock and 9 o'clock directions in the clock position are parallel to the horizontal direction (X-axis). The first region R1 can, for example, be formed between the 11 o'clock and 1 o'clock directions. The first region R1 can also, for example, be formed between the 12 o'clock and 1 o'clock directions. The central angle of the sector formed by the two ends of the first region R1 and the center (rotation axis) of the first roller 110 can be, for example, 1 to 45°.

[0086] The second region R2 is opposite to the relay plate 140. The range of the second region R2 can be adjusted, for example, by the size and shape of the relay plate 140. The second region R2 can be, for example, arc-shaped. The second region R2 can be formed, for example, between the 2 o'clock and 4 o'clock directions. The second region R2 can also be formed, for example, between the 2 o'clock and 3 o'clock directions. Thus, for example, it is expected to reduce the falling of particles 11 (yield loss). The central angle of the fan-shaped area formed by the two ends of the second region R2 and the center of the first roller 110 can be, for example, 1 to 45°.

[0087] 3rd roller

[0088] The third roller 130 is positioned between the hopper 160 and the relay plate 140 (see reference). Figure 3 The third roller 130 is opposite to the first roller 110. The third roller 130 may also be referred to as a "squeegee". In the gap between the first roller 110 and the third roller 130, the particles 11 are spread evenly. As a result, for example, it is possible to reduce the deviation in the supply of particles 11.

[0089] The diameter of the third roller 130 can, for example, be smaller than the diameter of the first roller 110. The rotation direction of the third roller 130 can, for example, be opposite to the rotation direction of the first roller 110. By rotating the third roller 130 in the opposite direction to the rotation direction of the first roller 110, the deviation in the feed amount of particles 11 (the thickness of the particle layer) can be reduced. Furthermore, a scraper of a form other than a roller can also be used. For example, a blade-type scraper can also be used.

[0090] relay board

[0091] The relay board 140 is conductive. The relay board 140 may be made of, for example, metal. The entire relay board 140 may be conductive, or only a portion of the relay board 140 may be conductive. For example, the surface layer of the relay board 140 may be conductive. The relay board 140 is electrically connected to the first power supply 151. The relay board 140 is also electrically connected to the second power supply 152 (see reference). Figure 3 ,4 ).

[0092] In a direction intersecting the vertical direction, the relay plate 140 separates from the first roller 110. In the horizontal direction, the relay plate 140 may also separate from the first roller 110. The gap between the relay plate 140 and the first roller 110 can, for example, be 10 to 50 times the D50 of the particle 11. This gap represents the shortest distance between the relay plate 140 and the first roller 110. The gap between the relay plate 140 and the first roller 110 can, for example, be 1 to 10 mm, or 2 to 6 mm.

[0093] Repeater board 140 includes region 3 R3 (refer to...) Figure 4 Region 3 R3 separates from Region 2 R2 in the direction intersecting the vertical direction. Region 3 R3 can also separate from Region 2 R2 in the horizontal direction.

[0094] The relay plate 140 can have any shape. For example, the relay plate 140 can be flat or curved. In the relay plate 140, the surface receiving the particles 11 can be, for example, spherical or parabolic. For example, a cross-section of the relay plate 140 parallel to the thickness direction (see reference...) Figure 3 , 4 The particles 11 can be bent or folded vertically downwards. In the first electrostatic coating, the particles 11 can reach the relay plate 140 from multiple directions. For example, by bending the relay plate 140, the position of the particles 11 adhering to the substrate 13 can be stabilized in the second electrostatic coating. Thus, for example, it is expected to reduce coating unevenness.

[0095] The relay board 140 can also be referred to as a "counter board". The relay board 140 includes a first counter surface 141 and a second counter surface 142 (see reference). Figure 4 The first opposing surface 141 is opposite to the first roller 110. The first opposing surface 141 can extend along the vertical direction. The second opposing surface 142 is opposite to the second roller 120 (substrate 13). The second opposing surface 142 can extend in a direction intersecting the vertical direction.

[0096] The second opposing surface 142 may be continuous with the first opposing surface 141. The second opposing surface 142 may also be separate from the first opposing surface 141. There are also cases where the second opposing surface 142 and the first opposing surface 141 are integrated and indistinguishable. For example, a portion of the second opposing surface 142 may overlap with the first opposing surface 141. For example, the entire second opposing surface 142 may overlap with the first opposing surface 141. The second opposing surface 142 may also be substantially identical to the first opposing surface 141. For example, when the relay plate 140 is flat, the second opposing surface 142 will be substantially identical to the first opposing surface 141.

[0097] Roller 2

[0098] The second roller 120 is conductive. The second roller 120 may be made of, for example, metal. The entire second roller 120 may be conductive, or only a portion of the second roller 120 may be conductive. For example, the portion in contact with the substrate 13 may be conductive. For example, the surface layer of the second roller 120 may be conductive. The second roller is electrically connected to the second power supply 152. The second roller 120 may also be grounded.

[0099] In the vertical direction, the second roller 120 is positioned lower than the first roller 110 and the relay plate 140 (see reference). Figure 3 The second roller 120 may be positioned, for example, directly below the first roller 110. The second roller 120 may be positioned, for example, directly below the relay plate 140. The diameter of the second roller 120 may be, for example, larger than the diameter of the first roller 110.

[0100] The gap between the second roller 120 and the relay plate 140 can be, for example, 20 to 100 times the D50 of the particle 11. This gap represents the shortest distance between the second roller 120 and the relay plate 140. The gap between the second roller 120 and the relay plate 140 can be, for example, 2 to 20 mm, or 6 to 10 mm.

[0101] The second roller 120 can also be referred to as a "support roller". The second roller 120 supports the substrate 13. The substrate 13 is transported by rotating the second roller 120. The second roller 120 transports the substrate 13 into the second electric field E2. In the vertical direction, the substrate 13 is located at a position lower than the third region R3 (see reference). Figure 4 ).

[0102] <Electrode Manufacturing Method>

[0103] Figure 5 This is a simplified flowchart of the electrode manufacturing method in this embodiment. Hereinafter, "electrode manufacturing method in this embodiment" will be abbreviated as "this manufacturing method". This manufacturing method includes "(a) particle preparation", "(b) supply", "(c) charging", "(d) roller conveying", "(e) first electrostatic coating", and "(f) second electrostatic coating". This manufacturing method may, for example, include "(g) fixing" after "(f) second electrostatic coating". The aforementioned manufacturing apparatus 100 can perform, for example, "(b) supply" to "(g) fixing".

[0104] This manufacturing method can produce electrodes, for example, used in lithium-ion batteries. However, lithium-ion batteries are just one example. This manufacturing method can be applied to any battery system. This manufacturing method can produce at least one of a positive electrode and a negative electrode.

[0105] (a) Particle preparation

[0106] This manufacturing method includes the step of preparing particles 11 comprising active substance powder and binder. Particles 11 are, in other words, precursors to the active substance layer 12. Particles 11 can be prepared by granulation of powder. Particles 11 comprise active substance powder and binder. That is, particles 11 can be prepared by granulation of a mixture of active substance powder and binder. The mixed powder can further comprise any component (conductive material, etc.). For example, particles 11 can be prepared by dry granulation or by wet granulation. In this manufacturing method, any dry granulator or wet granulator can be used.

[0107] Particle 11 is an aggregate of composite particles. One composite particle contains more than one active substance particle. One composite particle may also contain two or more active substance particles. One composite particle may also contain an aggregate of active substance particles.

[0108] Composite particles can have any shape. For example, composite particles can be in the form of pellets, spheres, flakes, columns, or irregular shapes.

[0109] Particle 11 may, for example, have a D50 of 50 to 500 μm. Particle 11 may, for example, have a D50 of 100 to 200 μm. By having a D50 of 100 to 200 μm, it is for example possible to expect that particle 11 will exhibit suitable flowability.

[0110] Granulation can improve flowability. The active ingredient powder (before granulation) can, for example, have an angle of repose greater than 50°. The particles 11 (after granulation) can, for example, have an angle of repose less than 50°. By having particles 11 with an angle of repose less than 50°, it is possible to expect reduced coating unevenness. Particles 11 can, for example, have an angle of repose less than 45°. Particles 11 can, for example, have an angle of repose greater than 30°.

[0111] <Active Substance Powder>

[0112] Active substance powders contain active substance particles. Active substance powders are aggregates of active substance particles. Active substance powders may have a D50 of 1–30 μm, 1–20 μm, or 1–10 μm, for example.

[0113] The active material particles undergo an electrode reaction. The active material particles can contain any components. They can contain, for example, a positive electrode active material. The active material particles can contain at least one material selected from, for example, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li(NiCoMn)O2, Li(NiCoAl)O2, and LiFePO4. For example, in "Li(NiCoMn)O2", "(NiCoMn)" indicates that the total proportions within the parentheses are 1. As long as the total is 1, the amount of each component is arbitrary. Li(NiCoMn)O2 can contain, for example, Li(Ni... 1 / 3 Co 1 / 3 Mn 1 / 3 O2, Li(Ni) 0.5 Co 0.2 Mn 0.3 O2, Li(Ni) 0.8 Co 0.1 Mn 0.1 O2, etc.

[0114] The active material particles may include, for example, a negative electrode active material. The active material particles may include, for example, graphite, soft carbon, hard carbon, silicon, silicon oxide, silicon-based alloys, tin, tin oxide, tin-based alloys, and Li4Ti5O. 12 At least one of them.

[0115] <Adhesive>

[0116] The adhesive can be in powder form. The adhesive bonds solid materials together in the active material layer 12. The amount of adhesive can be, for example, 0.1 to 10 parts by weight relative to 100 parts by weight of the active material powder. The adhesive can contain any components. The adhesive can contain at least one selected from, for example, polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), PVdF-HFP copolymer, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyimide (PI), polyamide-imide (PAI), and polyacrylic acid (PAA).

[0117] <Any ingredient>

[0118] Particles 11 may also include, for example, a conductive material. The conductive material may be in powder form. The conductive material can form an electronic conduction pathway in the active material layer 12. The amount of conductive material may be, for example, 0.1 to 10 parts by mass relative to 100 parts by mass of the active material powder. The conductive material may contain any components. The conductive material may include, for example, conductive carbon particles, conductive carbon fibers, etc. The conductive material may contain at least one selected from, for example, carbon black, vapor-grown carbon fibers, carbon nanotubes, and graphene sheets. The carbon black may contain at least one selected from, for example, acetylene black, furnace black, channel black, and thermal black.

[0119] Particles 11 may also contain, for example, a solvent. The solvent is a liquid. The solvent may also be dispersed in particles 11 as droplets. For example, the binder may absorb the solvent and swell. The solvent can contain any components. The solvent may contain at least one selected from, for example, water, N-methyl-2-pyrrolidone (NMP), and butyl butyrate. Particles 11 may, for example, have a solids content of 70-100%, 80-100%, or 90-100%.

[0120] Particle 11 may also include, for example, a solid electrolyte. That is, in this manufacturing method, an electrode 10 for an all-solid-state battery can also be manufactured. The solid electrolyte can be in powder form. The solid electrolyte can form ion conduction pathways in the active material layer 12. The solid electrolyte can contain any components. The solid electrolyte can contain at least one selected from, for example, Li₂S-P₂S₅, LiI-Li₂S-P₂S₅, LiBr-Li₂S-P₂S₅, and LiI-LiBr-Li₂S-P₂S₅.

[0121] (b) Supply

[0122] This manufacturing method includes the step of feeding particles 11 onto the surface of the first roller 110 (see reference). Figure 3 For example, granules 11 can be filled into hopper 160. Rotary feeder 161 can feed granules 11 into the first region R1 at, for example, a certain flow rate.

[0123] (c) Charged

[0124] This manufacturing method includes the step of charging the particles 11. Furthermore, in Figure 5 For convenience, "(c) Charging" is shown between "(b) Supply" and "(d) Roller Conveying". However, "(c) Charging" can be performed at any time between "(a) Particle Preparation" and "(e) First Electrostatic Coating". For example, "(c) Charging" and "(d) Roller Conveying" can also be performed simultaneously.

[0125] For example, the first power source 151 can supply charge (electrons) to the first roller 110. For example, the first roller 110 can inject charge into the particle 11 (see reference). Figure 3 Therefore, particle 11 can carry a negative charge.

[0126] (d) Roller conveying

[0127] This manufacturing method includes the step of conveying particles 11 from a first region R1 to a second region R2 by rotating a first roller 110 (see reference). Figure 3 In the vertical direction, region 2 R2 is located lower than region 1 R1. Region 2 R2 is located within the first electric field E1 (refer to...). Figure 4 ).

[0128] The particles 11 can be spread evenly on the surface of the first roller 110 before they reach the first electric field E1 (the second region R2). For example, the particles 11 can be spread evenly in the gap between the first roller 110 and the third roller 130. As a result, the supply of particles 11 to the first electric field E1 can be expected to be stable.

[0129] (e) First electrostatic coating

[0130] This manufacturing method includes the step of causing particle 11 to fly from region 2 R2 toward region 3 R3 by forming a first electric field E1 between region 2 R2 and region 3 R3 (see reference). Figure 4 ).

[0131] For example, the first power source 151 can apply a DC voltage between the first roller 110 and the relay plate 140. This creates a first electric field E1 between the second region R2 and the third region R3. A first electrostatic force F1 can act on the particles 11 supplied to the second region R2. Through the first electrostatic force F1, the particles 11 can detach from the first roller 110 and fly towards the relay plate 140.

[0132] (f) Second electrostatic coating

[0133] This manufacturing method includes the step of causing particles 11 to fly from the third region R3 toward the substrate 13 by forming a second electric field E2 between the third region R3 and the substrate 13 (see reference). Figure 4 The particles 11 that reach the substrate 13 can adhere to the substrate 13. This allows the formation of an active material layer 12. In other words, it enables the fabrication of an electrode 10.

[0134] For example, the second power source 152 can apply a DC voltage between the relay plate 140 and the second roller 120. This allows a second electric field E2 to be formed between the third region R3 and the substrate 13. A second electrostatic force F2 can act on the particles 11 attached to the relay plate 140. Furthermore, gravity F3 can also act on the particles 11. Through the combined force of the second electrostatic force F2 and gravity F3, the particles 11 can detach from the relay plate 140 and fly towards the substrate 13. It is expected that the particles 11 will be firmly attached to the substrate 13 by the combined force of the second electrostatic force F2 and gravity F3.

[0135] <Substrate>

[0136] The substrate 13 may be, for example, sheet-like. The substrate 13 may be, for example, strip-like. The substrate 13 is conductive. The substrate 13 may be a current collector. The substrate 13 may comprise, for example, a metal foil. The substrate 13 may comprise at least one selected from, for example, aluminum (Al) foil, Al alloy foil, copper (Cu) foil, Cu alloy foil, nickel (Ni) foil, Ni alloy foil, titanium (Ti) foil, and Ti alloy foil. The substrate 13 may, for example, have a thickness of 5–50 μm, or a thickness of 5–20 μm.

[0137] <Electric field strength>

[0138] The electrostatic force can be adjusted by the electric field strength. A first electric field E1 has a first electric field strength. A second electric field E2 has a second electric field strength. In the first electric field E1, a first electrostatic force F1 acts on particle 11. In the second electric field E2, in addition to the second electrostatic force F2, gravity F3 also acts on particle 11. Therefore, for example, the second electric field strength can be lower than the first electric field strength.

[0139] The first electric field strength is determined by dividing the DC voltage applied between the first roller 110 and the relay plate 140 by the gap (shortest distance) between them. If the first electric field strength is too low, there is a possibility that the particle 11 may not be able to fly. If the first electric field strength is too high, the impact of the particle 11 colliding with the relay plate 140 may become excessively large. Through the reaction force of the collision, the particle 11 may bounce back from the relay plate 140. The first electric field strength can be, for example, 75,000 to 300,000 V / m, or 100,000 to 200,000 V / m.

[0140] The second electric field strength is determined by dividing the DC voltage applied between the relay plate 140 and the second roller 120 by the gap (shortest distance) between them. If the second electric field strength is too low, there is a possibility that the particles 11 may not be able to adhere to the substrate 13. If the second electric field strength is too high, the impact of the particles 11 colliding with the substrate 13 may become excessively large. Through the reaction force of the collision, the particles 11 may bounce back from the substrate 13. The second electric field strength can be, for example, 37,500 to 150,000 V / m, or 50,000 to 100,000 V / m.

[0141] (g) Fixed

[0142] This manufacturing method may also include the step of fixing the active material layer 12 to the substrate 13 by applying pressure and heat to the active material layer 12. By fixing the active material layer 12, for example, it is expected to improve the peel strength of the active material layer 12.

[0143] Pressure and heat can be applied separately. Alternatively, pressure and heat can be applied substantially simultaneously. For example, the active material layer 12 can be compressed using hot rollers, hot plates, etc. The heating temperature of the active material layer 12 can be, for example, a temperature near the melting point of the adhesive. By softening, melting, and then curing the adhesive, an increase in adhesion can be expected. The heating temperature can be, for example, 80–200°C, 120–200°C, or 140–180°C.

[0144] The pressure can be adjusted according to the target thickness, target density, etc. of the active material layer 12. For example, a pressure of 50 to 200 MPa can be applied to the active material layer 12.

[0145] other

[0146] Based on the above description, electrode 10 can be manufactured. When the active material layer 12 (particles 11) contains a solvent, electrode 10 can also be dried. The electrode can also be cut into a predetermined planar shape to suit the battery design.

[0147] <Electrode>

[0148] Figure 6 This is a conceptual diagram illustrating an example of an electrode. Electrode 10 can be either a positive or negative electrode. Electrode 10 can have any shape to fit the battery design. Electrode 10 can be, for example, strip-shaped. Electrode 10 includes a substrate 13 and an active material layer 12. The active material layer 12 is disposed on the surface of the substrate 13. The active material layer 12 may be disposed on only one side of the substrate 13. The active material layer 12 may also be disposed on both the front and back sides of the substrate 13.

[0149] The active material layer 12 can have any thickness. For example, the active material layer 12 can have a thickness of 10–500 μm, or 50–200 μm. When the electrode 10 is a positive electrode, the active material layer 12 can have a thickness of, for example, 2–4 g / cm³. 3 The density. When electrode 10 is the negative electrode, the active material layer 12 can have, for example, a density of 1 to 2 g / cm³. 3 The density of the active material layer 12 is further expressed as "apparent density". Apparent density is obtained by dividing the mass of the active material layer 12 by its apparent volume. Apparent volume includes void volume.

[0150] The active material layer 12 may, for example, contain 1 to 10% binder, 0 to 10% conductive material, and the balance active material powder by mass fraction. The active material powder may contain either positive or negative electrode active material.

[0151] Example

[0152] <Electrode Manufacturing>

[0153] The following describes this embodiment. In the first manufacturing example, a positive electrode was manufactured. In the second manufacturing example, a negative electrode was manufactured.

[0154] Manufacturing Example 1

[0155] The following materials have been prepared.

[0156] Active substance powder: Li(NiCoMn)O2

[0157] Conductive material: Acetylene black

[0158] Adhesive: PVdF

[0159] Substrate 13: Al foil (12μm thickness)

[0160] An Artecniker mixing apparatus, the "High-Speed ​​Mixer," was prepared. Active material powder, conductive material, and binder were added to the mixing tank of the apparatus. The material ratio was "active material powder / conductive material / binder = 90 / 5 / 5 (mass ratio)." The stirring blade speed was set to 4500 rpm. The materials were mixed for 1 minute. A mixed powder was thus prepared. The mixed powder has an angle of repose of 59.6°.

[0161] A dry granulator was prepared. The mixed powder was granulated using the dry granulator. This resulted in particles 11. Each of the composite particles constituting particle 11 was formed into a thin sheet. Particle 11 was granulated using a 16-mesh metal mesh. The granulated particles 11 have a D50 of 100–200 μm. The granulated particles 11 have an angle of repose of 42.1°.

[0162] Prepared Figure 4 , 5 The electrode manufacturing apparatus. The settings of each part are as follows.

[0163] Electric field E1: Roller 110 (-1200V), relay plate 140 (-600V)

[0164] The gap between the first roller 110 and the relay plate 140: 4mm

[0165] First electric field strength: 150000 V / m

[0166] Second electric field E2: relay plate 140 (-600V), second roller 120 (0V, GND)

[0167] Gap between relay plate 140 and second roller 120: 8mm

[0168] Second electric field strength: 75000 V / m

[0169] Particles 11 are supplied from hopper 160 to the surface of first roller 110. Particles 11 become charged by receiving charge injection from first roller 110. Through the rotation of first roller 110, particles 11 are transported from first region R1 to second region R2. Particles 11 adhere to substrate 13 by sequentially flying through first electric field E1 and second electric field E2. Thus, an active material layer 12 is formed. That is, electrode 10 is manufactured. The active material layer 12 has a planar dimension of 60 mm × 200 mm.

[0170] Electrode 10 is sandwiched between two hot plates (flat plates). The temperature of the hot plates is 160°C. A load of 15 tf (ton-force) is applied to the active material layer 12 by the hot plates over 30 seconds. Thus, the active material layer 12 is fixed to the substrate 13.

[0171] Manufacturing Example 2

[0172] The following materials have been prepared.

[0173] Active material powder: amorphous carbon-coated graphite

[0174] Adhesive: PVdF

[0175] Substrate 13: Cu foil (8μm thickness)

[0176] In amorphous carbon-coated graphite, the surface of each graphite particle is coated with an amorphous carbon material. A high-speed mixing apparatus, manufactured by Artecnica, was prepared. Active material powder and binder were added to the mixing tank of the apparatus. The material ratio was "active material powder / binder = 97.5 / 2.5 (mass ratio)". The stirring blade speed was set to 4500 rpm. The materials were mixed for 1 minute. A mixed powder was thus prepared. The mixed powder has an angle of repose of 49.7°.

[0177] The mixed powder was granulated using a dry granulator. Particles 11 were thus prepared. Each of the composite particles constituting particle 11 was formed into a sheet shape. Particles 11 were granulated using a 16-mesh metal mesh. The granulated particles 11 have a D50 of 100–200 μm. The granulated particles 11 have an angle of repose of 44.3°. Apart from these, the electrode 10 was manufactured in the same manner as in the first manufacturing example.

[0178] <Manufacturing Results>

[0179] Figure 7 These are photographs showing the manufacturing results of the first and second manufacturing examples. In both the first and second manufacturing examples, no uneven coating was observed on the active material layer 12. Furthermore, in both the first and second manufacturing examples, the entire amount of particles 11 was used for the formation of the active material layer 12. That is, no substantial loss in yield occurred.

[0180] This embodiment and this example are illustrative in all respects. This embodiment and this example are not limiting. The scope of this disclosure includes all modifications within the meaning and scope equivalent to the claims. For example, it was assumed from the outset that any structure could be extracted from this embodiment and this example and combined arbitrarily.

Claims

1. An electrode manufacturing apparatus for manufacturing electrodes by attaching particles comprising active substance powder and binder to a substrate, comprising: Roller 1; Repeater board; The second roller; and Electric field forming device In a direction intersecting the vertical direction, the relay plate separates from the first roller. In the vertical direction, the second roller is positioned lower than the first roller and the relay plate. The electric field forming device is configured to form a first electric field between the first roller and the relay plate, and a second electric field between the relay plate and the second roller. The first roller is configured to transport the particles into the first electric field. The second roller is configured to transport the substrate into the second electric field.

2. The electrode manufacturing apparatus according to claim 1, It also includes the third roller. Furthermore, it is configured such that the particles are spread evenly in the gap between the first roller and the third roller before the particles reach the first electric field.

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