Method and apparatus for dry and solvent-free production of an electrode using powder

Abstract

【Solution means】A system for dry manufacturing an electrode for an energy storage device includes a substrate configured to move in a feed direction. Further, the system includes a powder application device configured to deposit dry powder on the surface of the substrate. Further, the system includes at least one pair of dispersion rollers. The pair of dispersion rollers includes an upper dispersion roller and a lower dispersion roller disposed below the upper dispersion roller. The upper dispersion roller and the lower dispersion roller are disposed downstream of the powder application device in the feed direction. Each dispersion roller has a rotation central axis and a radially outer surface. The radially outer surface of the upper dispersion roller is configured to directly contact the dry powder and disperse the dry powder on the substrate. The upper dispersion roller is configured to rotate in a rotation direction opposite to the feed direction of the substrate in the vicinity of the substrate and the dry powder, and the lower dispersion roller is configured to rotate in the same rotation direction as the rotation direction of the upper dispersion roller. Further, the system includes at least one pair of compression rollers. The pair of compression rollers includes an upper compression roller and a lower compression roller disposed below the upper compression roller. The at least one pair of dispersion rollers is disposed downstream of the upper dispersion roller and the lower dispersion roller with respect to the feed direction. Each compression roller has a rotation central axis and a radially outer surface. The radially outer surface of the upper compression roller is configured to directly contact the dry powder, compress the dry powder, and form an electrode on the surface of the substrate. The upper compression roller is configured to rotate in a rotation direction opposite to the rotation direction of the upper dispersion roller.

Description

Technical Field

[0001] Reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 355,727, filed on June 27, 2022, entitled "Methods and Apparatus for Dry Manufacturing Electrodes Using Powder", the entire content of which is incorporated herein by reference for all purposes.

[0002] Description of Federally Sponsored Research and Development Not applicable.

[0003] Background The present disclosure generally relates to manufacturing methods and manufacturing apparatuses. Specifically, the present disclosure relates to methods and apparatuses for dry manufacturing electrodes for energy storage devices such as batteries (e.g., lithium-ion batteries, solid-state batteries, etc.).

Background Art

[0004] The production capacity of lithium-ion batteries (LIBs) is expected to increase significantly in the next few years. Therefore, it is expected that in order to meet the demand for lithium-ion batteries, the manufacturing capacity needs to be increased by about four times in the next ten years. Argonne National Lab estimates that the cost of manufacturing facilities for battery electrodes alone could be about $66 million per 5 GWh factory. To build a new production capacity of 1000 GWh, 200 such factories need to be built.

[0005] The rapid growth of battery manufacturing has a significant impact on energy consumption and greenhouse gas emissions. For example, a current 5 GWh lithium-ion battery factory consumes approximately 565 GWh of electricity per year. In particular, conventional methods for manufacturing lithium-ion battery electrodes use drying that requires a large amount of energy, environmentally harmful solvents, and slurry casting techniques that require a relatively large installation area.

[0006] All-solid-state battery (ASSB) technology is expected to become the mainstream battery technology in the next few years due to its potential to achieve safer and higher energy density batteries. However, all-solid-state batteries pose new requirements and challenges in the manufacturing of battery electrodes, such as film thickness, uniformity, and the interface between the electrolyte and the active material. In particular, many organic polar solvents have an adverse effect on solid-state electrolytes (SSEs). The poor miscibility between the solid electrolyte and the solvent is a major factor hindering the commercialization of some types of all-solid-state batteries based on solid electrolytes. As a result, conventional slurry-based battery manufacturing technologies that rely on solvents cannot be directly applied to the manufacturing of thin-film solid electrolytes and composite electrodes for all-solid-state batteries. To avoid the problem of miscibility with solvents, solvent-free or dry-mixing-based pelletization processes that dry-mix solid electrolytes, additives, and active materials and then perform a mechanical pressing process have been attempted in laboratory-scale manufacturing. However, such dry-mixing-based pelletization processes have issues related to scalable manufacturing.

Summary of the Invention

[0007] This application discloses an embodiment of a system for dry manufacturing an electrode for an energy storage device. As one embodiment, a system for dry manufacturing an electrode for an energy storage device has a substrate configured to move in a feed direction. Further, the system includes a powder application device configured to deposit dry powder on the surface of the substrate. Further, the system includes at least one pair of dispersion rollers. The at least one pair of dispersion rollers includes an upper dispersion roller and a lower dispersion roller disposed below the upper dispersion roller. The upper dispersion roller and the lower dispersion roller are disposed downstream of the powder application device in the feed direction. Each dispersion roller has a rotation central axis and a radially outer surface, and the radially outer surface of the upper dispersion roller is configured to directly contact the dry powder and disperse it on the substrate. The upper dispersion roller is configured to rotate in a rotation direction opposite to the feed direction of the substrate in the vicinity of the substrate and the dry powder, and the lower dispersion roller is configured to rotate in the same rotation direction as the rotation direction of the upper dispersion roller. Further, the system includes at least one pair of compression (consolidation) rollers. The at least one pair of compression rollers includes an upper compression roller and a lower compression roller disposed below the upper compression roller. The upper compression roller and the lower compression roller are disposed downstream of the at least one pair of dispersion rollers in the feed direction. Each compression roller has a rotation central axis and a radially outer surface. The radially outer surface of the upper compression roller is configured to directly contact and compress the dry powder to form an electrode on the surface of the substrate. The upper compression roller is configured to rotate in a rotation direction opposite to the rotation direction of the upper dispersion roller.

[0008] This application discloses an embodiment of a method for dry manufacturing an electrode for an energy storage device. As one embodiment, a method for dry manufacturing an electrode for an energy storage device includes the process of depositing dry powder on the surface of a substrate moving in a feed direction. Further, the method includes the process of, after (a), conveying the dry powder together with the substrate under a first dispersion roller rotating in a first rotation direction to disperse the dry powder on the substrate. The first rotation direction is opposite to the feed direction at the contact point between the first dispersion roller and the dry powder. Further, the method includes the process of, after (b), conveying the dry powder together with the substrate under a compression roller rotating in a second rotation direction opposite to the first rotation direction to compress the dry powder composition and manufacture an electrode on the surface of the substrate.

[0009] The embodiments described herein include combinations of features and characteristics intended to address various drawbacks associated with certain conventional devices, systems, and methods. The foregoing is a rather general overview of the features and technical characteristics of the disclosed embodiments and is provided to enable a better understanding of the following detailed description. The various characteristics and features described above, as well as other characteristics and features, will be readily understood by those skilled in the art upon reading the following detailed description and referring to the accompanying drawings. It should be understood that the disclosed concepts and specific embodiments are readily available as a basis for modifying or designing other structures for carrying out the same purposes as the disclosed embodiments. It should also be understood that such equivalent structures do not depart from the spirit and scope of the principles disclosed in this application.

Brief Description of the Drawings

[0010] For a detailed description of various exemplary embodiments, reference is now made to the accompanying drawings.

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

[0011] The following discussion is directed to various exemplary embodiments. However, one of ordinary skill in the art will understand that the examples disclosed herein have broad applications, and that any discussion of an embodiment is intended only as an illustration of that embodiment and does not suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

[0012] In the following description and claims, specific terms are used to refer to particular features or components. As one of ordinary skill in the art will appreciate, different people may refer to the same feature or component by different names. This document is not intended to distinguish between components or features that have different names but the same function. The drawings are not necessarily to scale. Certain features or components of this document may be shown with exaggerated scale, in somewhat schematic form, or with some details of conventional elements not shown for clarity and conciseness.

[0013] Unless the context indicates otherwise, all ranges defined in this application should be interpreted as including their endpoints, and ranges without defined limits should be interpreted as including only commercially practical values. Similarly, unless the context provides otherwise, all lists of values should be considered to include intermediate values.

[0014] In the following discussion and claims, the terms "comprising" and "including" are used in an open-ended fashion and should therefore be interpreted to mean "including but not limited to". Also, the term "coupled" is intended to mean either an indirect or direct connection. Thus, when a first device is coupled to a second device, the connection may be made through a direct engagement between the two devices or through an indirect connection consisting of other devices, components, nodes, connections. Further, as used herein, the terms "axial" and "axially" generally mean along or parallel to a particular axis (e.g., the central axis of a body or port), and the terms "radial" and "radially" generally mean perpendicular to a particular axis. For example, an axial distance refers to a distance measured along or parallel to an axis, and a radial distance means a distance measured perpendicular to an axis. In this specification and the claims, the terms "upper" and "lower" are for the purpose of clarity, and "upward", "upper side", "upward direction", "(hole) upward", "upstream" mean toward the surface of the hole regardless of the direction of the hole, and "downward", "lower side", "downward direction", "(hole) downward", "downstream" mean toward the end of the hole. Terms such as "approximately", "about", "substantially" used in this application mean within 10% of the stated value (i.e., plus or minus 10%). Thus, for example, an angle described as "about 80 degrees" refers to an angle in the range of 72 degrees to 88 degrees.

[0015] As described above, the methods for manufacturing electrodes for conventional energy storage devices (e.g., lithium-ion batteries, all-solid-state batteries, etc.) usually have high energy requirements, rely on environmentally harmful solvents, may require a relatively large installation area, and may not be expandable for large-scale production. Therefore, embodiments of the systems and methods for manufacturing electrodes for energy storage devices disclosed in the present application are directed to solvent-free (or "dry") technologies that are environmentally friendly and offer the potential to reduce energy consumption and greenhouse gas emissions. For example, the systems and methods for dry manufacturing the electrodes disclosed in the present application are estimated to be able to reduce power consumption by up to about 40% compared to the slurry molding technology for manufacturing electrodes for conventional lithium-ion batteries. In particular, switching from conventional slurry casting technology to embodiments of the systems and methods for dry manufacturing the electrodes described herein may reduce the annual power consumption in a 5 GWh lithium-ion battery factory to 226 GWh and the CO2 emissions to 94,000 tons. Given that the lithium-ion battery production volume in 2030 is predicted to be 1300 GWh, switching to the systems and methods for dry and solvent-free manufacturing of the electrodes described herein may reduce the annual power consumption and CO2 emissions by 58760 GWh and 2.444 million tons, respectively. Most of these reductions are due to the reduction in energy usage by eliminating the need for solvent drying and solvent recovery. Although these estimates are based on the manufacture of lithium-ion batteries, it is expected that the manufacture of all-solid-state batteries will follow a similar trend.

[0016] Next, referring to FIG. 1, one embodiment of a system 100 for dry manufacturing an electrode for an energy storage device such as a lithium-ion battery or an all-solid-state battery is shown. More specifically, this system 100 forms a continuous sheet or layer of electrode material 101 on a web or substrate 105. The electrode material 101 and the substrate 105 can be cut as needed to produce a plurality of individual electrodes for the energy storage device. Therefore, in this specification, for clarity and for further explanation, the electrode material 101 may also be referred to as the electrode 101.

[0017] In this embodiment, the system 100 includes a pay - out roller or supply roller 110, a take - up roller or receiving roller 120 arranged horizontally spaced from the supply roller 110, a powder supply device or powder applying device 130, a pair of dispersing rollers 140, 141 arranged vertically, a pair of compression rollers 150, 151 arranged vertically horizontally spaced from the dispersing rollers 140, 141, and a plurality of air bearings 160 arranged horizontally spaced. The dispersing rollers 140, 141 are arranged horizontally between the compression rollers 150, 151 and the supply roller 110, and the compression rollers 150, 151 are arranged horizontally between the take - up roller 120 and the dispersing rollers 140, 141. In this embodiment, one air bearing 160 is arranged horizontally between the supply roller 110 and the dispersing rollers 140, 141, and the other air bearing 160 is arranged horizontally between the dispersing rollers 140, 141 and the compression rollers 150, 151. Although a pair of dispersing rollers 140, 141 and a pair of compression rollers 150, 151 are shown in FIG. 1, in another embodiment, two or more pairs of dispersing rollers (e.g., dispersing rollers 140, 141) arranged in series and / or two or more pairs of compression rollers (e.g., compression rollers 150, 151) arranged in series are provided, and it should be understood that each dispersing roller is arranged between a supply roller (e.g., supply roller 110) and a compression roller (e.g., compression rollers 150, 151). Further, in the system 100 shown in FIG. 1, the number of pairs of dispersing rollers 140, 141 and compression rollers 150, 151 is the same (one pair of dispersing rollers 140, 141 and one pair of compression rollers 150, 151), but as another embodiment, the number of pairs of dispersing rollers (e.g., dispersing rollers 140, 141) and the number of pairs of compression rollers (e.g., compression rollers 150, 151) may be different (e.g., one pair of dispersing rollers 140, 141 and multiple pairs of compression rollers 150, 151, or vice versa).

[0018] The supply roller 110 generally supplies a continuous sheet of the base material 105 which serves as the base on which the electrode 101 is formed in the system 100. The base material 105 is unwound from the supply roller 110 or supplied by another roller (not shown), and is passed through the supply roller 110 to the rest of the system 100. The supply roller 110 rotates in the rotational direction 111 about the central axis 115, and feeds the base material 105 in a substantially horizontal feed direction 106 through the system 100. As shown in FIG. 1, the rotational direction 111 is counterclockwise, and the feed direction 106 is leftward. In the embodiment described herein, the base material 105 is supplied from the supply roller 110 and moves in the feed direction 106 at a feed rate greater than 0.0 m / min and less than or equal to 80.0 m / min.

[0019] The receiving roller 120 generally receives a continuous sheet of the base material 105 and the electrode 101 formed thereon. The base material 105 and the electrode 101 are wound around the receiving roller 120 or passed through the receiving roller 120 to another roller (not shown). The receiving roller 120 rotates in the rotational direction 121 around the central axis 125, and receives the base material 105 and the electrode 101 along the substantially horizontal feed direction 106. As shown in FIG. 1, the rotational direction 121 is counterclockwise, and thus is the same as the rotational direction 111 of the supply roller 110. As described above, in the embodiment described herein, the base material 105 is moved in the feed direction 106 at a feed rate in the range greater than 0.0 m / min and less than or equal to 80.0 m / min, and thus the base material 105 and the electrode 101 formed thereon are received by the receiving roller 120 at the same speed.

[0020] In the embodiments described herein, the substrate 105 preferably includes a conductive base material 107 in the form of a sheet of conductive material and a friction-enhancing coating 108 applied to the upper surface of the base material 107. Generally, the base material 107 can be a sheet of any suitable conductive material, including but not limited to a sheet of aluminum foil or a sheet of copper foil. The friction-enhancing coating 108 on the surface of the base material 107 can be any suitable material for (i) increasing the coefficient of friction between the surface of the substrate 105 and the dry powder 131, and (ii) increasing the adhesion between the electrode 101 and the substrate 105, including but not limited to carbon coatings and polyvinylidene fluoride (PVDF) coatings. In one embodiment, the base material 107 is aluminum foil and the friction-enhancing coating 108 is carbon. The substrate 105 has a thickness T 105 measured perpendicular between its upper and lower surfaces. In the embodiments described herein, the thickness T 105 of the substrate 105 ranges from 1.0 micron to 200.0 microns, or alternatively from 1.0 micron to 30.0 microns.

[0021] The powder application device 130 supplies the dry powder 131 for forming the electrode 101 onto the substrate 105. Specifically, the powder application device 130 applies the dry powder 131 onto the upper surface of the substrate 105, and the substrate 105 conveys and moves the dry powder 131 to the dispersion rollers 140, 141 in the supply direction 105, and then to the compression rollers 150, 151. The dispersion rollers 140, 141 disperse the dry powder 131 onto the substrate 105, and then the compression rollers 150, 151 compress the dispersed dry powder 131 onto the substrate 105 to form the electrode 101 on the substrate 105. In most electrode manufacturing processes, the mass supply rate of the dry powder 131 onto the substrate 105 is greater than 0.0 grams / s and less than or equal to 20.0 grams / s per 100 mm width of the substrate 105. The dry powder 131 is "dry", which should be understood to mean that it does not contain a solvent.

[0022] In an embodiment where the electrode 101 is manufactured for use in a Li-ion battery, the dry powder 131 includes an active material, a binder, and a conductive additive (each in powder form). When the electrode 101 is manufactured for a solid Li-ion battery, optionally one or more solid electrolytes (also in powder form) can be included in the dry powder 131. The active material can include, but is not limited to, cathode (positive electrode) materials such as lithium nickel cobalt manganese oxide (NMC), lithium iron phosphate (LFP), lithium cobalt oxide (LCO), or combinations thereof, and anode (negative electrode) materials such as graphite, carbonaceous anode materials (e.g., graphite, graphene, disordered carbon, etc.), lithium transition metal oxides, Si-based composite materials, or combinations thereof. The binder can include, but is not limited to, one or more of polymer materials, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyethylene oxide (PEO), polytetrafluoroethylene (PTFE), polymethyl methacrylate (PMMA), carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), polyurethane, ethylene vinyl acetate (EVA), acrylic polymers, polyethylene (PE). The conductive additive can include, but is not limited to, one or more of carbon black, carbon nanotubes, carbon fibers, graphene, etc. The one or more solid electrolytes can include, but are not limited to, solid polymer electrolyte PEO / LiTFSI, lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanate (LLTO), Li3InCl6, Li6PS5Cl, silica nanofiller, Al2O3 nanofiller, LLZO nanofiller, or combinations thereof. In some embodiments, the solid electrolyte can function as a binder, in which case the binder may be described as including the solid electrolyte.

[0023] In an embodiment in which the electrode 101 is manufactured for use in an all-solid-state battery, the dry powder 131 contains an active material (the same as that described above for use in a Li-ion battery), a solid electrolyte (the same as that described above for use in a Li-ion battery), and additives (each in powder form). The additives include, but are not limited to, a binder (the same as that described above for use in a Li-ion battery), a conductive additive (the same as that described above for use in a Li-ion battery), or a combination thereof.

[0024] Regardless of whether the electrode 101 is manufactured for use in a lithium-ion battery or a all-solid-state battery, the dry powder 131 contains at least 70 wt% active material and less than 30 wt% of other components. Further, the dry powder 131 preferably contains a plurality of microparticles at least partially coated with a plurality of nanoparticles (i.e., each microparticle is at least partially coated with a plurality of nanoparticles). As used herein, the term "microparticle" refers to particles having a size (e.g., diameter) of 1.0 micron or more, and the term "nanoparticle" refers to particles having a size (e.g., diameter) of less than 1.0 micron. Thus, in the embodiments described herein, the size of the microparticles in the dry powder 131 is preferably at least 10 times the size of the nanoparticles. The size of the components (e.g., active material, binder, conductive additive, solid electrolyte, etc.) in the dry powder 131 can range from nanometers (e.g., nanoparticles) to tens of microns (e.g., microparticles). For example, the size of the active material can range from 0.5 micron to 40 microns, while the size of the conductive additive and a part of the solid polymer electrolyte (e.g., nanofiller) can be less than 1 micron. Generally, any one or more of the individual components (e.g., active material, binder, conductive additive, solid electrolyte, etc.) in the dry powder 131 can be used as microparticles, and any one or more of the individual components (e.g., active material, binder, conductive additive, solid electrolyte, etc.) in the dry powder 131 can be used as nanoparticles. For example, referring briefly to FIG. 2A, a single active material microparticle 190, a plurality of conductive additive nanoparticles 191, and a plurality of solid electrolyte nanoparticles 192 are shown. The active material microparticle 190 has a size at least 10 times that of the conductive additive nanoparticles 191 and the solid electrolyte nanoparticles 192. In FIG. 2B, a state is shown in which the active material microparticle 190 is coated with the conductive additive nanoparticles 191 and the solid electrolyte nanoparticles 192 to form one nanoparticle-coated microparticle 193. A plurality of such nanoparticle-coated microparticles 193 can be used as the dry powder 131.

[0025] Although not limited to this theory or a particular theory, the nano-particle coated microparticles in the dry powder 131 have the advantage that the cohesiveness and shear thinning characteristics of the dry powder 131 are reduced, thereby improving the fluidity of the dry powder 131 during dispersion and compression on the substrate 105, and enabling the continuous and uniform formation of the electrode 101 by dry molding (dry casting) to be advantageously possible. In particular, the nano-particle coated microparticles are considered to be able to reduce cohesiveness and friction even when the shear rate increases. The nano-particle coated microparticles forming the dry powder 131 are prepared by any suitable means (such as dry mixing) known in the art and then introduced into a powder applying device 130 for controlled deposition on the substrate 105.

[0026] Continuing to refer to FIG. 1, the dispersion rollers 140, 141 uniformly disperse the dry powder 131 on the upper surface of the substrate 105 and the friction enhancing coating 108. The dispersion rollers 140, 141 are vertically arranged, and thus can be described as the upper dispersion roller 140 and the lower dispersion roller 141. Each dispersion roller 140, 141 has a central axis 145 that rotates in the rotational direction 146, a cylindrical surface 142 on the outer radial side, and an outer diameter D sand. In this embodiment, the dispensing rollers 140, 141 are arranged such that the central axes 145 are in a common vertical plane. However, in other embodiments, the central axes of the dispensing rollers (e.g., the central axes 145 of the dispensing rollers 140, 141) do not lie in a common vertical plane. As a result, the uppermost part of the outer surface 142 of the lower roller 141 directly faces the lowermost part of the outer surface 142 of the upper roller 140 vertically. The lower part of the upper roller 140 directly contacts the dry powder 131 to disperse the dry powder 131 onto the substrate 105, and the upper part of the lower roller 141 directly contacts the lower surface of the substrate 105 to support the substrate 105. In this embodiment, the upper part of the lower dispensing roller 141 is arranged slightly above the upper part of the supply roller 110, and the substrate 105 is slightly inclined upward when moving from the supply roller 110 to the dispensing rollers 140, 141. More specifically, in some embodiments, the substrate 105 is inclined upward at an angle greater than 0.0° and less than or equal to 15.0° with respect to the horizontal when moving from the supply roller 110 to the dispensing rollers 140, 141. As another embodiment, the substrate 105 can be made to be horizontal between the supply roller 110 and the dispensing rollers 140, 141 without being inclined upward when moving from the supply roller 110 to the dispensing rollers 140, 141.

[0027] The outer diameter D of each spraying roller 140, 141 s is in the range of 5.0 mm to 200.0 mm. In this embodiment, the outer diameter D of the dispensing rollers 140, 141 s is the same, but in other embodiments, the outer diameter D of the dispensing rollers 140, 141 s may be different.

[0028] Each dispensing roller 140, 141 rotates at a uniform rotational speed about the corresponding axis 145. In the embodiments described herein, the rotational speed of each dispensing roller 140, 141 is preferably in the range of 0.1 to 200.0 RPM. In this embodiment, the rotational speeds of both dispensing rollers 140, 141 are the same, but as another embodiment, the rotational speeds of the dispensing rollers 140, 141 may be different.

[0029] The rotation directions 146 of the dispersion rollers 140 and 141 are the same. For example, in FIG. 1, the rotation directions 146 of the dispersion rollers 140 and 141 are both counterclockwise. However, since the dispersion rollers 140 and 141 are respectively arranged above and below the base material 105 and the dry powder 131, the rotation direction 146 of the upper dispersion roller 140 is generally opposite to the feeding direction 106 in the vicinity of the base material 105 and the dry powder 131, while the rotation direction 146 of the lower dispersion roller 141 is generally in the same direction as the feeding direction in the vicinity of the base material 105. In particular, due to the rotation direction 146 of the upper dispersion roller 140, the lower part of the outer surface 142 of the upper dispersion roller 140 that contacts the dry powder 131 moves in a direction opposite to the feeding direction 106. However, due to the rotation direction 146 of the lower dispersion roller 141, the upper part of the outer surface 142 of the lower dispersion roller 141 that contacts the base material 105 moves in the same direction as the feeding direction 106. For example, as shown in FIG. 1, at the location where the outer surface 142 of the upper dispersion roller 140 engages with the dry powder 131, the outer surface 142 of the upper dispersion roller 140 generally moves to the right, while the feeding direction 106 is to the left. Also, at the location where the outer surface 142 of the lower dispersion roller 141 engages with the base material 105, the outer surface 142 of the lower dispersion roller 141 generally moves to the left, while the feeding direction 106 is to the left. Therefore, the upper dispersion roller 140 can be expressed as "rotating in reverse" with respect to the feeding direction 106. The reverse rotation of the upper dispersion roller 140 that contacts the dry powder 131 provides the possibility of improving the uniformity of the dispersion of the dry powder 131 onto the base material 105 (for example, the thickness of the dry powder 131 dispersed on the base material 105 becomes more uniform).

[0030] The dispersion rollers 140 and 141 are arranged at a vertical interval of a distance sufficient to provide a gap G s measured vertically from the upper surface of the base material 105 to the lowermost part of the outer surface 142 of the upper dispersion roller 140. Therefore, the vertical distance between the dispersion rollers 140 and 141 is equal to the thickness T 105 plus the gap G s The gap G sIt should be understood that the vertical thickness of the dry powder 131 dispersed on the substrate 105 by the dispersing rollers 140, 141 is defined. In the embodiments described herein, the gap G s , and thus the vertical thickness of the dry powder 131 after passing between the dispersing rollers 140, 141, is in the range of 0 to 2000 microns, or alternatively in the range of 20.0 microns to 500.0 microns.

[0031] In the embodiments described herein, the outer cylindrical surface 142 of the counter-rotating dispersing roller 140 that is in direct contact with the dry powder 131 is preferably a low-friction surface in order to reduce the friction between the dispersing roller 140 and the dry powder 131. The low-friction surface preferably has an average surface roughness Ra of less than 0.05 microns, or alternatively less than 0.02 microns. Generally, the low-friction surface can be formed by surface treatment or coating. Examples of surface treatment and coating include, but are not limited to, polished surfaces, carbide coatings, ceramic coatings, chrome plating, PTFE coatings, and graphite coatings (or the entire roller 140 can be made of a graphite material).

[0032] As described above, the upper dispersing roller 140 in contact with the dry powder 131 preferably has an outer surface 142 with reduced friction, and the upper surface of the substrate 105 in direct contact with the dry powder 131 preferably includes a coating 108 that increases friction. More specifically, the coefficient of friction (μ 基板-粉末 ) between the substrate 105 and the dry powder 131 is preferably greater than the coefficient of friction (μ ローラー-粉末 ) between the dispersing roller 141 and the dry powder 131. Combining these features provides the advantage that the minimum principal stress applied to the dry powder 131 between the dispersing roller 140 and the substrate 105 is maintained at zero or more, thereby enabling reliable continuous dry casting of the dry powder 131 via the counter-rotating dispersing rollers 140, 141.

[0033] After passing between the dispersion rollers 140 and 141, in order to achieve the desired uniformity of the thickness of the dry powder 131 (i.e., the uniformity of the gap G along both the length and width of the substrate 105) s In order to achieve the uniformity), the dispersion rollers 140 and 141 are preferably manufactured with relatively strict tolerances and oriented relative to each other. More specifically, each of the dispersion rollers 140 and 141 preferably has a radial runout error of 3.0 microns or less, or 1.0 micron or less after manufacturing and assembly, and the dispersion rollers 140 and 141 are preferably oriented such that the rollers 140 and 141 exhibit a roller parallelism of 5.0 microns or less, or 1.0 micron or less. The terms "radial runout error" and "roller parallelism" used in the present application have the meanings known in the art. Specifically, the term "radial runout error" refers to the variation in the outer radius of the roller (the difference between the maximum radius and the minimum radius), and the term "roller parallelism" refers to the variation in the distance between the central axes of the rollers oriented substantially parallel to each other (the difference between the maximum distance and the minimum distance).

[0034] Referring to FIG. 1 again, the compression rollers 150 and 151 uniformly compress the dispersed dry powder 131 (after passing through the dispersion rollers 140 and 141) onto the upper surface of the substrate 105 and the friction enhancing coating 108. The compression rollers 150 and 151 are vertically arranged, and thus can be described as the upper compression roller 150 and the lower compression roller 151. Each of the compression rollers 150 and 151 has a central axis 155 that rotates in the rotational direction 156, a cylindrical surface 152 on the radially outer side, and an outer diameter D cIt has the following. The compression rollers 150 and 151 are arranged such that the central axis 155 is present in a common vertical plane. However, in another embodiment, the central axes of the compression rollers (for example, the central axis 155 of the dispersion rollers 150 and 151) are not present in a common vertical plane. As a result, the uppermost part of the outer surface 152 of the lower roller 151 directly faces the lowermost part of the outer surface 152 of the upper roller 150 in the vertical direction. The lower part of the upper roller 150 directly contacts the dry powder 131 on the substrate 105 and compresses it, and the upper part of the lower roller 151 directly contacts the lower surface of the substrate 105 and supports it. In the embodiment described herein, the compression rollers 150 and 151 can apply a compression load of up to about 3.5 tons / cm (along the line contact between the roller 150 and the dry powder 131) to disperse the dry powder 131, and more preferably, a compression load in the range of 0.1 to 1.5 tons / cm (along the line contact between the roller 150 and the dry powder 131) can be applied to disperse the dry powder 131.

[0035] The outer diameter D of each fastening roller 150, 151 c is in the range of 100.0 mm to 300.0 mm. In this embodiment, the outer diameter D of the compression rollers 150 and 151 c is the same, but in other embodiments, the outer diameter D of the compression rollers 150 and 151 c may be different. Each compression roller 150, 151 rotates at a uniform rotational speed about the corresponding axis 155. In the embodiment described herein, the rotational speed of each compression roller 150, 151 is preferably in the range of 0.1 to 80.0 RPM. In this embodiment, the rotational speeds of both compression rollers 150 and 151 are the same, but as another embodiment, the rotational speeds of the compression rollers 150 and 151 may be different.

[0036] The rotation directions 156 of the compression rollers 150 and 151 are opposite to each other. For example, in FIG. 1, the rotation direction 156 of the upper compression roller 150 is clockwise, while the rotation direction 156 of the lower compression roller 151 is counterclockwise. However, since the compression rollers 150 and 151 are respectively arranged above and below the base material 105 and the dry powder 131, the rotation direction 156 is substantially the same as the feeding direction 106 close to the base material 105 and the dry powder 131. In particular, due to the rotation direction 156 of the upper compression roller 150, the lower part of the outer surface 152 of the upper compression roller 150 in contact with the dry powder 131 moves in the same direction as the feeding direction 106. Also, due to the rotation direction 156 of the lower compression roller 151, the upper part of the outer surface 152 of the lower compression roller 151 in contact with the base material 105 moves in the same direction as the feeding direction 106. For example, as shown in FIG. 1, at the location where the outer surface 152 of the upper compression roller 140 is involved with the dry powder 131, the outer surface 152 of the upper compression roller 150 generally moves leftward, and the feeding direction 106 is also leftward. Also, at the location where the outer surface 152 of the lower compression roller 151 is involved with the base material 105, the outer surface 152 of the lower compression roller 151 generally moves leftward, and the feeding direction 106 is also leftward. Therefore, both compression rollers 150 and 151 can be expressed as "non-reverse rotation" with respect to the feeding direction 106.

[0037] The compression rollers 150 and 151 are vertically spaced by a distance sufficient to provide a gap G measured vertically from the upper surface of the base material 105 to the lowermost part of the outer surface 152 of the upper compression roller 150. c They are arranged at a vertical interval. Therefore, the vertical distance between the compression rollers 150 and 151 is equal to the thickness T 105 plus the gap G c . The gap G c should be understood to define the vertical thickness by which the dry powder 131 is compressed by the compression rollers 140 and 141 on the base material 105 to form the electrode 101. Therefore, the gap G c defines the thickness of the electrode 101. In the embodiments described in this specification, the gap G cTherefore, the vertical thickness of the dry powder 131 after passing between the compression rollers 150 and 151 and the thickness of the electrode 101 are in the range of 0 to 2000.0 microns, or in the range of 20.0 microns to 200.0 microns.

[0038] Continuing to refer to FIG. 1, the supply roller 110, the receiving roller 120, the lower dispersion roller 141, and the lower compression roller 151 directly contact the substrate 105 (and components disposed on the substrate 105 such as the dry powder 131 and the electrode 101) to support the substrate 105. In this embodiment, an air bearing 160 is also provided to support the substrate 105 (and components disposed on the substrate 105 such as the dry powder 131) without contact. The air bearing 160 also reduces the vertical vibration of the substrate 105 and enables the substrate 105 (and the components on the substrate) to be fed more accurately. In the embodiments described herein, each air bearing 160 is configured to provide both a positive pressure air cushion 161 (above ambient atmospheric pressure) and a negative pressure suction 162 (below ambient atmospheric pressure), so as to support the substrate 105 without friction, while reducing the vibration of the substrate 105 and enabling a relatively high-speed production process. In the embodiments described herein, the air bearing 160 preferably minimizes the vertical vibration (measured vertically from the lowest point of the substrate 105 to the highest point of the substrate 105) of the portion of the substrate 105 disposed horizontally between the rollers 110, 120, 140, 141, 150, 152 to less than 3.0 microns.

[0039] Next, referring to FIG. 3, one embodiment of a method 200 for manufacturing the electrode 101 on the substrate 105 is shown. Since the method 200 is performed using the system 100 described above and shown in FIG. 1, it will be described with reference to the system 100.

[0040] In this embodiment, method 200 begins with block 201 of preparing dry powder 131. As described above, dry powder 131 includes a plurality of micro-particles coated with nano-particles (e.g., micro-particles 193 coated with nano-particles) and is "dry" (i.e., does not contain a solvent and is not prepared using a solvent). Next, in block 202, dry powder 131 is loaded into powder applying device 130, and in block 203, substrate 105 moves in feed direction 106 via rollers 110, 120. Next, it moves to block 204 where dry powder 131 is deposited onto substrate 105 via powder applying device 130. Substrate 105 (moving in feed direction 106) conveys dry powder 131 through the remaining part of system 100. In particular, substrate 105 conveys dry powder 131 from powder applying device 130 to dispersion rollers 140, 141, then from dispersion rollers 140, 141 to compression rollers 150, 151, and then from compression rollers 150, 151 to receiving roller 120 in feed direction 106. Therefore, rollers 140, 141, 150, 151 can be described as being downstream of powder applying device 130 in feed direction 106, compression rollers 150, 151 can be described as being downstream of dispersion rollers 140, 141 and powder applying device 130, and receiving roller 120 can be described as being downstream of rollers 140, 141, 150, 151 and powder applying device 130. While dry powder 131 is being conveyed within system 100, substrate 105 is vertically supported by rollers 141, 151 and air bearing 160. Also, air bearing 160 functions to reduce the vibration of substrate 105 as described above.

[0041] Continuing to refer to FIG. 3, substrate 105 conveys dry powder 131 between dispersion rollers 140, 141, and dispersion rollers 140, 141 disperse dry powder 131 onto substrate 105. Some features of system 100 are gap G sIt is specially designed and configured so that the dry powder 131 is surely uniformly and homogeneously dispersed to the desired thickness defined thereby. In particular, the system 100 includes a friction-enhancing coating 108 that contacts the dry powder 131, a low-friction outer surface 142 of the upper dispersion roller 140 that contacts the dry powder 131, reverse-rotation dispersion rollers 140, 141 that move in a rotational direction 146 generally opposite to the feed direction 106 in the vicinity of the dry powder 131, and a gap G s It includes high-precision dispersion rollers 140, 141 (manufactured with relatively strict tolerances regarding radial runout error and roller parallelism and arranged relative to each other) for surely uniformly dispersing the dry powder 131 to the desired thickness defined by s . Next, when moving to block 206, the substrate 105 conveys the dispersed dry powder 131 between the compression rollers 150, 151, and the compression rollers 150, 151 compress the dry powder 131 on the substrate 105 to form the electrode 101.

[0042] In the embodiment of the system 100 shown and described above with reference to FIG. 1, the electrode 101 is formed on one side of the substrate 105. However, as another embodiment, the electrodes can also be formed on both sides of the substrate. For example, referring to FIG. 4, an embodiment of a system 100' for dry manufacturing electrodes for energy storage devices such as lithium-ion batteries and all-solid-state batteries is shown. The system 100' is substantially the same as the aforementioned system 100 except that continuous sheets or layers of the electrode material 101 are formed on both sides of the substrate 105'. Therefore, the same reference numerals are given to the features of the system 100' that are the same as those of the system 100, and for clarity and brevity, such common features are not described in detail on the understanding that they are the same as those described previously for the system 100. The electrode material 101 and the substrate 105' can be cut as needed to manufacture a plurality of individual electrodes for energy storage devices. For this reason, for clarity and for further explanation, each layer of the electrode material 101 may also be referred to as the electrode 101 in this specification.

[0043] Continuing to refer to FIG. 4, in this embodiment, the system 100' includes a supply roller 110, a receiving roller 120 disposed horizontally spaced from the supply roller 110, a powder applying device 130, a pair of dispersion rollers 140, 141, a pair of compression rollers 150, 151, and a plurality of air bearings 160, each as described above. The supply roller 110 generally supplies a continuous sheet of the substrate 105' for forming the electrode 101 in the system 100', and the receiving roller 120 generally receives the continuous sheet of the substrate 105' and the electrode 101 formed thereon.

[0044] The substrate 105' is the same as the aforementioned substrate 105. In particular, the substrate 105' includes a conductive base material 107 in the form of a sheet of a conductive material and a friction enhancing coating 108 applied to the upper surface of the base material 107. However, in this embodiment, the friction enhancing coating 108 is also applied to the lower surface of the base material 107. In order to manufacture the electrode 101 on both sides of the substrate 105', the substrate 105' is passed through the system 100' twice. More specifically, the substrate 105' is first passed through the system 100' to form the electrode 101 on the upper surface of the substrate 105', then the substrate 105 is turned over, and then passed through the system 100' a second time to form the electrode 101 on the upper surface of the substrate 105'. This upper surface was the lower surface of the substrate 105' when it was first passed through the system 100'. The first pass of passing the substrate 105' through the system 100' to form the electrode 101 on one side of the substrate 105' is the same as described above. The second pass of passing the substrate 105' through the system 100' to form the electrode 101 on the opposite side of the substrate 105' is such that the vertical distance between the lower dispersion roller 141 and the substrate 105', the vertical distance between the lower compression roller 151 and the substrate 105', and the vertical distance between the air bearing 160 and the substrate 105' are increased by only the gap G c except that it is the same as described above in that it can accommodate the previously formed electrode 101 which is in the vertical direction between the rollers 141, 151 and the substrate 105' and in the vertical direction between the air bearing 160 and the substrate 105'.

[0045] As described, embodiments of the systems (e.g., systems 100, 100') and methods (e.g., method 200) described herein can be used to dry manufacture electrodes of energy storage devices such as batteries (e.g., lithium-ion batteries, solid-state batteries, etc.). Such embodiments may offer several advantages over conventional systems and methods. In particular, the embodiments described herein can enhance the uniformity of dry powders and electrodes and are applicable to a wide range of electrode compositions. Further, forming electrodes using powders "dried" in accordance with the embodiments described herein eliminates the need for solvent drying and recovery, thus reducing manufacturing costs, the floor area of manufacturing equipment, and energy consumption.

[0046] Although the preferred embodiments have been illustrated and described, those skilled in the art can make those changes without departing from the scope or teachings of this specification. The embodiments described herein are merely exemplary and not limiting. Many variations and modifications are possible to the systems, devices, and processes described herein, and all of them are within the scope of the disclosure. For example, the relative dimensions of various components, the materials of various components, and other parameters can be changed. Accordingly, the scope of protection is not limited to the embodiments described herein but is limited only by the subsequent claims, which shall include all equivalents of the subject matter of the claims. Unless explicitly stated otherwise, the steps in the method claims can be performed in any order. The descriptions of identifiers such as (a), (b), (c) or (1), (2), (3), etc. preceding the steps in the method claims are not intended to, nor do they, specify a particular order of the steps, but rather are used to simplify subsequent references to such steps.

Claims

1. A system for dry manufacturing an electrode for an energy storage device, comprising: a substrate configured to move in a feed direction; a powder application device configured to deposit dry powder on the surface of the substrate; at least one pair of dispersion rollers, the at least one pair of dispersion rollers including an upper dispersion roller and a lower dispersion roller disposed below the upper dispersion roller, the upper dispersion roller and the lower dispersion roller being disposed downstream of the powder application device in the feed direction, each dispersion roller having a rotation central axis and a radially outer surface, the radially outer surface of the upper dispersion roller being configured to directly contact the dry powder to disperse the dry powder on the substrate; the upper dispersion roller is configured to rotate in a rotation direction opposite to the feed direction of the substrate in the vicinity of the substrate and the dry powder, and the lower dispersion roller is configured to rotate in the same rotation direction as the rotation direction of the upper dispersion roller; further comprising at least one pair of compression rollers, the at least one pair of compression rollers including an upper compression roller and a lower compression roller disposed below the upper compression roller, the upper compression roller and the lower compression roller being disposed downstream of the at least one pair of dispersion rollers in the feed direction, each compression roller having a rotation central axis and a radially outer surface, the radially outer surface of the upper compression roller being configured to directly contact the dry powder to compress the dry powder and form an electrode on the surface of the substrate; a system in which the upper compression roller is configured to rotate in a rotation direction opposite to the rotation direction of the upper dispersion roller.

2. The system according to claim 1, wherein the upper dispersion roller is spaced upward from the surface of the base material by a gap G s only, and the upper compression roller is spaced upward from the surface of the base material by a gap G s smaller than the gap G c only.

3. The system of claim 2, wherein the gap G s and the gap G c are each in the range of 0 to 2000 microns.

4. The system according to claim 3, wherein the gap G s is in the range of 20.0 microns to 500.0 microns, and the gap G c is in the range of 20.0 microns to 200.0 microns.

5. The system according to claim 1, wherein the substrate includes a conductive base and a friction-enhancing coating applied to the conductive base.

6. The system according to claim 5, wherein the conductive base includes a sheet of conductive foil, and the friction-enhancing coating includes carbon.

7. The system according to claim 5, wherein a coefficient of friction μ between the radially outer surface of the first dispersion roller and the dry powder ローラー－粉末 is smaller than a coefficient of friction μ between the friction-enhancing coating of the substrate and the dry powder 基材－粉末 of the system.

8. The system according to claim 1, wherein the dry powder includes microparticles coated with a plurality of nanoparticles.

9. The system according to claim 1, further comprising an air bearing disposed below the substrate and supporting the substrate, the air bearing being configured to reduce vibration of the substrate.

10. The system according to claim 1, wherein an outer surface in the radial direction of the lower dispersion roller contacts the substrate to support the substrate, a radial runout error of each of the dispersion rollers is 3.0 microns or less, and a roller parallelism between a central axis of the upper spraying roller and a central axis of the lower dispersion roller is 5.0 microns or less.

11. The system according to claim 1, wherein the dry powder comprises an active material, and a binder.

12. The system according to claim 11, wherein the active material is a cathode material selected from the group consisting of lithium nickel cobalt manganese oxide (NMC), lithium iron phosphate (LFP), lithium cobalt oxide (LCO), or combinations thereof, or is an anode material selected from the group consisting of graphite, a carbonaceous anode material, a lithium transition metal oxide, an Si-based composite material, or combinations thereof.

13. The system according to claim 11, wherein the dry powder further comprises a solid electrolyte.

14. The system according to claim 11, wherein the binder comprises a polymer material, a solid electrolyte, or a combination thereof.

15. The system according to claim 11, wherein the dry powder further comprises a conductive material.

16. The system according to claim 1, wherein the substrate has a thickness in the range of 1.0 micron to 30.0 microns.

17. A method for dry manufacturing an electrode for an energy storage device, comprising: (a) depositing a dry powder on a surface of a substrate moving in a feed direction; after (a), (b) conveying the dry powder on the substrate under a first dispersion roller rotating in a first rotation direction to disperse the dry powder on the substrate, the first rotation direction being opposite to the feed direction at a point where the first dispersion roller contacts the dry powder; and after (b), (c) conveying the dry powder together with the substrate under a compression roller rotating in a second rotation direction opposite to the first rotation direction to compress a dry powder composition and generate an electrode on the surface of the substrate.

18. The method of claim 17, wherein in said (b), the first dispersion roller is rotated at a first rotational speed, and in said (c), the compression roller is rotated at a second rotational speed, the first rotational speed being in the range of 0.1 to 200.0 RPM and the second rotational speed being in the range of 0.1 to 80.0 RPM.

19. The method of claim 17, wherein said (b) includes a process of dispersing the dry powder to a first thickness measured from the surface of the substrate to the first dispersion roller, and said (c) includes a process of compressing the dry powder to a second thickness measured from the surface of the substrate to the compression roller, the second thickness being smaller than the first thickness.

20. The method of claim 19, wherein the first thickness and the second thickness are each in the range of 0.0 to 2000.0 microns.

21. The method of claim 20, wherein the first thickness is in the range of 20.0 to 500.0 microns and the second thickness is in the range of 20.0 to 200.0 microns.

22. The method of claim 17, wherein the substrate has a conductive base and a friction-enhancing coating applied to the conductive base, and in said (a), the dry powder is deposited on the friction-enhancing coating of the substrate.

23. The method according to claim 17, wherein the first dispersion roller has a radially outer surface that contacts and disperses the dry powder in (b), and a coefficient of friction μ between the radially outer surface of the first dispersion roller and the dry powder ローラー－粉末 is smaller than the coefficient of friction μ between the friction-enhanced coating of the substrate and the dry powder 基材－粉末 than the method.

24. The method of claim 17, wherein the dry powder includes microparticles coated with a plurality of nanoparticles.

25. The method of claim 17, further comprising: (d) between said (a), (b), and (c), a process of supporting the substrate with one or more air bearings disposed below the substrate; and (e) by applying both positive-pressure air cushion and negative-pressure suction to the substrate using the one or more air bearings, a process of reducing vibration of the substrate using the one or more air bearings between said (a), (b), and (c).

26. The method of claim 17, wherein said (b) further includes: a process of conveying the dry powder on the substrate onto a second dispersion roller that rotates in a first rotational direction; and a process of bringing the substrate into contact with the second dispersion roller, each dispersion roller has a rotation central axis and a radially outer surface, and the radial runout error of each dispersion roller is 3.0 microns or less. A method in which the central axis of the first dispersion roller and the central axis of the second dispersion roller have a roller parallelism of 5.0 microns or less.

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