Method and apparatus for solvent-free production of electrodes using powder drying

Abstract

A system for dry manufacturing an electrode of an energy storage device includes a substrate configured to move in a feed direction. Further, the system includes a powder applicator configured to deposit a dry powder onto the surface of the substrate. Further, the system includes at least one pair of spreading rollers. The pair of spreading rollers comprises an upper spreading roller and a lower spreading roller located below the upper spreading roller. The upper spreading roller and the lower spreading roller are positioned downstream of the powder applicator with respect to the feed direction. Still further, the system includes at least one pair of compaction rollers.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 355,727, filed on June 27, 2022, entitled “Method and Apparatus for Dry Manufacturing of Electrode Using Powders,” the entire contents of which are incorporated herein by reference for all purposes.

[0003] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0004] not applicable. Technical Field

[0005] The present disclosure relates generally to manufacturing methods and apparatus. More specifically, the present disclosure relates to methods and apparatus for dry manufacturing of electrodes for energy storage devices such as batteries (eg, lithium-ion batteries, solid-state batteries, etc.). Background Art

[0006] Lithium-ion battery (LIB) production capacity is expected to grow significantly in the coming years. Therefore, it is expected that about 4 times more manufacturing capacity will be needed in the next decade to meet the demand for lithium-ion batteries. Argonne National Lab has estimated that for each 5GWh factory, the battery electrode manufacturing equipment alone may cost about $66 million. In order to establish 1,000GWh of new production capacity, 200 such factories need to be built.

[0007] The rapid growth of battery manufacturing has had a significant impact on energy consumption and greenhouse gas emissions. For example, a current 5GWh lithium-ion battery factory consumes about 565GWh / year of electricity. In particular, conventional methods for manufacturing electrodes for Li-ion batteries utilize slurry casting techniques, which require energy-intensive drying, environmentally harmful solvents, and a relatively large footprint.

[0008] All-solid-state battery (ASSB) technology is expected to become the dominant battery technology in the coming years due to its prospects for safer and more energy-dense batteries. However, solid-state batteries pose new requirements and challenges for battery electrode manufacturing, including film thickness, uniformity, and electrolyte-active material interface. In particular, many organic polar solvents are harmful to solid electrolytes (SSEs). The poor compatibility of solid electrolytes with solvents is an important factor hindering the commercialization of selected types of solid electrolytes based on all-solid-state batteries. Therefore, conventional slurry-based battery manufacturing techniques that rely on solvents cannot be directly applied to the manufacture of thin-film solid electrolytes and composite electrodes for all solid-state batteries. In order to circumvent the solvent compatibility issue, solvent-free or dry-mixing based stacking processes have been attempted in laboratory-scale manufacturing, in which solid electrolytes, additives, and active material materials are dry-mixed and then subjected to a mechanical pressing process. However, such dry-mixing based stacking processes are challenging in terms of scalable manufacturing. Summary of the invention

[0009] Embodiments of systems for dry manufacturing of electrodes for energy storage devices are disclosed herein. In one embodiment, a system for dry manufacturing of electrodes for energy storage devices includes a substrate configured to move in a feed direction. In addition, the system includes a powder applicator configured to deposit dry powder onto the surface of the substrate. In addition, the system includes at least one pair of spreading rollers. At least one pair of spreading rollers includes an upper spreading roller and a lower spreading roller located below the upper spreading roller. The upper spreading roller and the lower spreading roller are positioned downstream of the powder applicator relative to the feed direction. Each spreading roller has a central rotation axis and a radial outer surface, wherein the radial outer surface of the upper spreading roller is configured to directly contact and spread the dry powder on the substrate. The upper spreading roller is configured to rotate in a rotation direction opposite to the feed direction of the substrate near the substrate and the dry powder, and the lower spreading roller is configured to rotate in a rotation direction identical to the rotation direction of the upper spreading roller. Further, the system includes at least one pair of compacting rollers. At least one pair of compacting rollers includes an upper compacting roller and a lower compacting roller located below the upper compacting roller. The upper compacting roller and the lower compacting roller are located downstream of at least one pair of spreading rollers relative to the feed direction. Each compacting roller has a central rotation axis and a radial outer surface. The radial outer surface of the upper compacting roller is configured to directly contact and compress the dry powder to form an electrode on the surface of the substrate. The upper compacting roller is configured to rotate in a rotation direction opposite to the rotation direction of the upper spreading roller.

[0010] Disclosed herein are embodiments of methods for dry manufacturing of electrodes for energy storage devices. In one embodiment, the method for dry manufacturing of electrodes for energy storage devices includes (a) depositing dry powder onto the surface of a substrate moving in a feed direction. In addition, the method includes (b) after (a), conveying the dry powder onto the substrate under a first spreading roller rotating in a first rotational direction to spread the dry powder on the substrate. The first rotational direction is opposite to the feed direction at the contact point between the first spreading roller and the dry powder. In addition, the method includes (c) after (b), conveying the dry powder and the substrate to under a compacting roller rotating in a second rotational direction opposite to the first rotational direction to compress the dry powder composition and produce an electrode on the surface of the substrate.

[0011] The embodiments described herein include combinations of features and characteristics that are intended to address various shortcomings associated with certain existing devices, systems, and methods. The features and technical characteristics of the disclosed embodiments have been outlined quite extensively above so that the following detailed description can be better understood. By reading the following detailed description and referring to the accompanying drawings, the various characteristics and features described above and other characteristics and features will be apparent to those skilled in the art. It should be understood that the disclosed concepts and specific embodiments can be easily used as the basis for modifying or designing other structures for performing the same purpose as the disclosed embodiments. It should also be recognized that such equivalent constructions do not depart from the spirit and scope of the principles disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For a detailed description of various exemplary embodiments, reference will now be made to the accompanying drawings, in which:

[0013] Figure 1 is a schematic side view of an embodiment of a system for dry manufacturing of electrodes for energy storage devices according to principles described herein;

[0014] Figure 2A Can be used to form Figure 1 Schematic diagram of exemplary micron particles and a plurality of exemplary nanoparticles of a dry powder;

[0015] Figure 2B Is Figure 2A A schematic diagram of an exemplary nanoparticle-coated microparticle formed of an exemplary microparticle and an exemplary nanoparticle;

[0016] Figure 3 is a schematic side view of an embodiment of a system for dry manufacturing of electrodes for energy storage devices according to principles described herein; and

[0017] Figure 4 is a schematic diagram of an embodiment of a method for dry manufacturing an electrode for an energy storage device according to principles described herein. DETAILED DESCRIPTION

[0018] The following discussion relates to various exemplary embodiments. However, those skilled in the art will appreciate that the examples disclosed herein have broad applications, and the discussion of any embodiment is only meant to be an example of that embodiment, and is not intended to imply that the scope of the present disclosure (including claims) is limited to that embodiment.

[0019] Certain terms are used throughout the following description and claims to refer to particular features or components. As will be appreciated by those skilled in the art, 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 differ in name but function the same. The drawings are not necessarily drawn to scale. Certain features and components herein may be shown exaggerated in proportion or in slightly schematic form, and some details of conventional elements may not be shown for clarity and conciseness.

[0020] Unless the context dictates otherwise, all ranges set forth herein should be interpreted as including their endpoints, and open ranges should be interpreted as including only commercially practical values. Similarly, unless the context dictates otherwise, all value lists should be deemed to include intermediate values.

[0021] In the following discussion and claims, the terms "include" and "comprising" are used in an open-ended manner and should therefore be interpreted to mean "including but not limited to ...". In addition, the terms "couple" or "couples" are intended to indicate an indirect or direct connection. Thus, if a first device is coupled to a second device, the connection may be through a direct engagement between the two devices, or through an indirect connection established via other devices, components, nodes, and connections. In addition, 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), while 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 refers to a distance measured perpendicular to an axis. Any reference to upward or downward in the specification and claims is for the purpose of clarity, where "upward", "upper", "upwardly", "uphole" or "upstream" means toward the surface of a borehole, and where "downward", "lower", "downwardly", "downhole" or "downstream" means toward the terminal end of a borehole, regardless of the borehole orientation. As used herein, the terms "approximately," "about," "substantially," and the like mean within 10% (ie, plus or minus 10%) of the stated value. Thus, for example, an angle of "about 80 degrees" means an angle within the range of 72 to 88 degrees.

[0022] As described above, conventional methods for manufacturing electrodes for energy storage devices (e.g., Li-ion batteries, all-solid-state batteries, etc.) typically have high energy requirements, rely on environmentally harmful solvents, may require a relatively large footprint, and may not be scalable for large-scale production. Therefore, embodiments of the systems and methods for manufacturing electrodes for energy storage devices disclosed herein relate to solvent-free (or "dry") technologies that are environmentally friendly and provide the potential to reduce energy consumption and greenhouse gas emissions. For example, it is estimated that the dry electrode manufacturing systems and methods disclosed herein can provide up to about 40% reduction in electricity consumption compared to conventional slurry casting techniques for manufacturing electrodes for lithium-ion batteries. In particular, the conversion from conventional slurry casting techniques to embodiments of dry electrode manufacturing systems and methods as described herein provides the potential to reduce annual electricity consumption by 226GWh and reduce CO2 emissions from a 5GWh lithium-ion battery factory by 94,000 tons. Based on a projected lithium-ion battery production of 1,300 GWh in 2030, the annual reductions in electricity consumption and CO2 emissions by switching to a dry, solvent-free electrode manufacturing system and method as described herein can be 58,760 GWh and 24,440,00 tons, respectively. Most of these reductions are due to reduced energy use by eliminating the requirement for solvent drying and solvent recovery. While these estimates are based on Li-ion battery manufacturing, it is expected that the manufacturing of all solid-state batteries will follow similar trends.

[0023] Reference now Figure 1 , an embodiment of a system 100 for dry manufacturing of electrodes for energy storage devices (e.g., Li-ion batteries and all-solid-state batteries) is shown. More specifically, the system 100 produces a continuous sheet or layer of electrode material 101 on a web or substrate 105. The electrode material 101 and substrate 105 can be cut as needed to produce multiple individual electrodes for energy storage devices. Therefore, for the purpose of clarity and further explanation, the electrode material 101 may also be referred to as electrode 101 herein.

[0024] In this embodiment, the system 100 includes an unwind or supply roller 110, a winding or receiving roller 120 horizontally spaced apart from the supply roller 110, a powder feeder or applicator 130, a pair of vertically arranged spreading rollers 140, 141, a pair of vertically arranged compacting rollers 150, 151 horizontally spaced apart from the spreading rollers 140, 141, and a plurality of horizontally spaced apart air bearings 160. The spreading rollers 140, 141 are horizontally positioned between the compacting rollers 150, 151 and the supply roller 110, and the compacting rollers 150, 151 are horizontally positioned between the winding roller 120 and the spreading rollers 140, 141. In this embodiment, one air bearing 160 is horizontally positioned between the supply roller 110 and the spreading rollers 140, 141, and another air bearing 160 is horizontally positioned between the spreading rollers 140, 141 and the compacting rollers 150, 151. Although Figure 1 A pair of spreading rollers 140, 141 and a pair of compacting rollers 150, 151 are shown in FIG, but it should be understood that in other embodiments, two or more pairs of tandem spreading rollers (e.g., spreading rollers 140, 141) and / or two or more pairs of tandemly arranged compacting rollers (e.g., compacting rollers 150, 151) may be provided, wherein each spreading roller is located between a supply roller (e.g., supply roller 110) and a compacting roller (e.g., compacting rollers 150, 151). In addition, Figure 1 The system 100 shown includes the same number of pairs of spreading rollers 140, 141 and compacting rollers 150, 151 (a pair of spreading rollers 140, 141 and a pair of compacting rollers 150, 151), and in other embodiments, the number of pairs of spreading rollers (e.g., spreading rollers 140, 141) and the number of pairs of compacting rollers (e.g., compacting rollers 150, 151) may be different (e.g., a pair of spreading rollers 140, 141 and multiple pairs of compacting rollers 150, 151, or vice versa).

[0025] The supply roll 110 generally provides a continuous sheet of substrate 105 on which the electrode 101 is formed using the system 100. The substrate 105 can be unwound from the supply roll 110, or provided by another roll (not shown) and passed over the supply roll 110 to the rest of the system 100. The supply roll 110 rotates in a rotational direction 111 about a central axis 115 to supply the substrate 105 through the system 100 in a generally horizontal feed direction 106. Figure 1 As shown, the rotation direction 111 is counterclockwise and the feed direction 106 is leftward. In the embodiments described herein, the substrate 105 is fed from the supply roll 110 and moves in the feed direction 106 at a feed rate or speed greater than 0.0 m / min and less than or equal to 80.0 m / min.

[0026] The receiving roller 120 generally receives a continuous sheet of the substrate 105 and the electrode 101 formed thereon. The substrate 105 and the electrode 101 may be wound onto the receiving roller 120 or passed through the receiving roller 120 to another roller (not shown). The receiving roller 120 rotates in a rotation direction 121 about a central axis 125 to receive the substrate 105 and the electrode 101 along a generally horizontal feed direction 106. Figure 1 As shown, the rotation direction 121 is counterclockwise and is therefore the same as the rotation direction 111 of the supply roller 110. As previously described, in the embodiments described herein, the substrate 105 moves in the feed direction 106 at a feed rate or speed ranging from greater than 0.0 m / min and less than or equal to 80.0 m / min, and therefore, the substrate 105 and the electrode 101 formed thereon are received by the receiving roller 120 at the same rate.

[0027] In the embodiments described herein, the substrate 105 preferably includes a conductive base 107 in the form of a sheet of conductive material and a friction enhancing coating 108 applied to the upper surface of the base 107. In general, the base 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 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 a carbon coating or a polyvinylidene fluoride (PVDF) coating. In one embodiment, the base 107 is an aluminum foil and the friction enhancing coating 108 is carbon. The substrate 105 has a thickness T measured vertically between its upper and lower surfaces. 105 In the embodiments described herein, the thickness T of the substrate 105 is 105 In the range of 1.0 micron to 200.0 microns, or in the range of 1.0 micron to 30.0 microns.

[0028] The powder applicator 130 supplies a dry powder 131 that forms the electrode 101 on the substrate 105. In particular, the powder applicator 130 applies the dry powder 131 to the upper surface of the substrate 105, and the substrate 105 carries and moves the dry powder 131 to the spreading rollers 140, 141 in the feeding direction 105, and then to the compacting rollers 150, 151. The spreading rollers 140, 141 spread the dry powder 131 on the substrate 105, and then the compacting rollers 150, 151 compact the spread dry powder 131 on the substrate 105 to form the electrode 101 on the substrate 105. For most electrode manufacturing operations, the mass feed rate of the dry powder 131 to the substrate 105 is greater than 0.0 g / s and less than or equal to 20.0 g / s per 100 mm width of the substrate 105. It should be understood that the dry powder 131 is "dry", meaning that it does not include any solvent.

[0029] In an embodiment where the electrode 101 is manufactured for a Li-ion battery, the dry powder 131 includes an active material, a binder, and a conductive additive (each in powder form). Optionally, when the electrode 101 is manufactured for a solid-state Li-ion battery, one or more solid electrolytes (also in powder form) may be included in the dry powder 131. The active material may include, but is not limited to, a cathode material such as lithium nickel cobalt manganese oxide (NMC), lithium iron phosphate (LFP), lithium cobalt oxide (LCO), or a combination thereof; and an anode material such as graphite, a carbonaceous anode material (e.g., graphite, graphene, disordered carbon, etc.), a lithium transition metal oxide, a Si-based composite material, or a combination thereof. The binder may include, but is not limited to, one or more of a polymer material, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyethylene oxide (PEO), polytetrafluoroethylene (PTFE), poly(methyl methacrylate) (PMMA), carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyurethane, ethylene vinyl acetate (EVA), acrylic polymer, and polyethylene (PE). Conductive additives may include, but are not limited to, one or more of carbon black, carbon nanotubes, carbon fibers, graphene, etc. The one or more solid electrolytes may include, but are not limited to, solid polymer electrolytes PEO / LiTFSI, lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanate (LLTO), Li3InCl6, Li6PS5Cl, silica nanofillers, Al2O3 nanofillers, LLZO nanofillers, or combinations thereof. In some embodiments, the solid electrolyte may be used as a binder, in which case the binder may be described as comprising a solid electrolyte.

[0030] In an embodiment where the electrode 101 is manufactured for an all-solid-state battery, the dry powder 131 includes an active material (same as described above for Li-ion batteries), a solid electrolyte (same as described above for Li-ion batteries), and additives (each in powder form). The additives may include, but are not limited to, a binder (same as described above for Li-ion batteries), a conductive additive (same as described above for Li-ion batteries), or a combination thereof.

[0031] Whether the electrode 101 is manufactured for a lithium-ion battery or an all-solid-state battery, the dry powder 131 includes at least 70 wt% of active materials and less than 30 wt% of other components. In addition, the dry powder 131 preferably includes a plurality of micron particles at least partially coated in a plurality of nanoparticles (i.e., each micron particle is at least partially coated in a plurality of nanoparticles). As used herein, the term "micron particle" refers to a particle having a size (e.g., diameter) greater than or equal to 1.0 micron, and the term "nanoparticle" refers to a particle having a size (e.g., diameter) less than 1.0 micron. Therefore, in the embodiments described herein, the size of the micron particles in the dry powder 131 is preferably at least 10 times the size of the nanoparticles. The size of the components in the dry powder 131 (e.g., active materials, binders, conductive additives, solid electrolytes, etc.) can range from nanometers (e.g., nanoparticles) to tens of microns (e.g., micron particles). For example, the active material can have a size of 0.5 microns to 40 microns, while the conductive additive and some solid polymer electrolytes (e.g., nanofillers) can have a size less than 1 micron. Generally, any one or more individual components of dry powder 131 (e.g., active material, binder, conductive additive, solid electrolyte, etc.) can be used as micron particles, and any one or more individual components of dry powder 131 (e.g., active material, binder, conductive additive, solid electrolyte, etc.) can be used as nanoparticles. For example, briefly referring to Figure 2A , showing a single active material micron particle 190, a plurality of conductive additive nanoparticles 191, and a plurality of solid electrolyte nanoparticles 192. The size of the active material micron particle 190 is at least 10 times the size of the conductive additive nanoparticle 191 and the solid electrolyte nanoparticle 192. Figure 2B , it is shown that active material microparticles 190 are coated in conductive additive nanoparticles 191 and solid electrolyte nanoparticles 192 to form one nanoparticle-coated microparticle 193. A plurality of such nanoparticle-coated microparticles 193 can be used as dry powder 131.

[0032] Without being limited to this theory or any particular theory, the nanoparticle-coated micron particles in the dry powder 131 advantageously exhibit reduced cohesiveness and shear-thinning properties of the dry powder 131, which enhances the fluidity of the dry powder 131 during spreading and compaction on the substrate 105 to advantageously allow dry casting, continuous and uniform formation of the electrode 101. In particular, it is believed that the nanoparticle-coated micron particles can reduce cohesion and friction at increased shear rates. The nanoparticle-coated micron particles that form the dry powder 131 are prepared by any suitable means known in the art (e.g., dry mixing) and then added to the powder applicator 130 for controlled deposition on the substrate 105.

[0033] Still reference Figure 1 , spreading rollers 140, 141 spread the dry powder 131 uniformly on the upper surface of the substrate 105 and the friction enhancing coating 108. The spreading rollers 140, 141 are arranged vertically one above the other, and therefore, can be described as an upper spreading roller 140 and a lower spreading roller 141. Each spreading roller 140, 141 has a central axis 145, a radially outer cylindrical surface 142, and an outer diameter D s , the spreading rollers 140, 141 rotate around the central axis 145 in the rotation direction 146. In this embodiment, the spreading rollers 140, 141 are positioned so that the central axis 145 is arranged in a common vertical plane. However, in other embodiments, the central axis of the spreading rollers (e.g., the central axis 145 of the spreading rollers 140, 141) is not located in a common vertical plane. Therefore, the uppermost portion of the outer surface 142 of the lower roller 141 is directly vertically opposite to the lowermost portion of the outer surface 142 of the upper roller 140. The lower portion of the upper roller 140 directly contacts and spreads the dry powder 131 on the substrate 105, while the upper portion of the lower roller 141 directly contacts and supports the lower surface of the substrate 105. In this embodiment, the upper portion of the lower spreading roller 141 is positioned slightly higher than the upper portion of the supply roller 110, so that the substrate 105 tilts slightly upward when it moves from the supply roller 110 to the spreading rollers 140, 141. More specifically, in some embodiments, the substrate 105 tilts upwardly, moving from the supply roller 110 to the spreading rollers 140, 141 at an angle greater than 0.0° and less than or equal to 15.0° relative to the horizontal plane. In other embodiments, the substrate 105 may not move upwardly tilted from the supply roller 110 to the spreading rollers 140, 141, but may be horizontally oriented therebetween.

[0034] The outer diameter D of each spreading roller 140, 141 s In the range of 5.0 mm to 200.0 mm. In this embodiment, the outer diameter D of the spreading rollers 140, 141 is s are the same, however, in other embodiments, the outer diameter D of the spreading rollers 140, 141 is s Can be different.

[0035] Each spreading roller 140, 141 rotates at a uniform rotational speed about its respective axis 145. In the embodiments described herein, the rotational speed of each spreading roller 140, 141 is preferably in the range of 0.1 to 200.0 RPM. In this embodiment, both spreading rollers 140, 141 have the same rotational speed, however, in other embodiments, the rotational speeds of the spreading rollers 140, 141 may be different.

[0036] The spreading rollers 140, 141 have the same rotation direction 146. Figure 1, the rotation direction 146 of the spreading rollers 140 and 141 are both counterclockwise. However, since the spreading rollers 140 and 141 are positioned above and below the substrate 105 and the dry powder 131, respectively, the rotation direction 146 of the upper spreading roller 140 is generally opposite to the feed direction 106 near the substrate 105 and the dry powder 131, while the rotation direction 146 of the lower spreading roller 141 is generally the same as the feed direction near the substrate 105. In particular, due to the rotation direction 146 of the upper spreading roller 140, the lower portion of the outer surface 142 of the upper spreading roller 140 that contacts the dry powder 131 moves in a direction opposite to the feed direction 106; however, due to the rotation direction 146 of the lower spreading roller 141, the upper portion of the outer surface 142 of the lower spreading roller 141 that contacts the substrate 105 moves in the same direction as the feed direction 106. For example, as Figure 1 As shown, at the point of engagement of the outer surface 142 of the upper spreading roller 140 with the dry powder 131, the outer surface 142 of the upper spreading roller 140 generally moves to the right, while the feed direction 106 moves to the left; and at the point of engagement of the outer surface 142 of the lower spreading roller 141 with the substrate 105, the outer surface 142 of the lower spreading roller 141 generally moves to the left, while the feed direction 106 is to the left. Therefore, the upper spreading roller 140 can be described as "counter-rotating" relative to the feed direction 106. The counter-rotation of the upper spreading roller 140 that contacts the dry powder 131 provides the possibility of improving the uniformity of the spreading of the dry powder 131 on the substrate 105 (e.g., a more uniform thickness of the dry powder 131 spread on the substrate 105).

[0037] The spreading rollers 140, 141 are vertically spaced a sufficient distance apart to provide a gap G measured vertically from the upper surface of the substrate 105 to the lowermost portion of the outer surface 142 of the upper spreading roller 140. s Therefore, the vertical distance between the spreading rollers 140, 141 is equal to the thickness T 105 Plus gap G s It should be understood that the gap G s The vertical thickness of the dry powder 131 spread on the substrate 105 by the spreading rollers 140 and 141 is defined. s And the vertical thickness of the dry powder 131 after passing between the spreading rollers 140, 141 is in the range of 0 to 2,000 microns, or in the range of 20.0 microns to 500.0 microns.

[0038] In the embodiments described herein, the outer cylindrical surface 142 of the counter-rotating spreading roller 140 that directly contacts the dry powder 131 is preferably a low friction surface to reduce the friction between the spreading roller 140 and the dry powder 131. The low friction surface preferably exhibits an average surface roughness Ra of less than 0.05 microns, or less than 0.02 microns. Typically, the low friction surface can be defined by a surface treatment or coating. Examples of surface treatments and coatings 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).

[0039] As previously described, the upper spreading roller 140 in contact with the dry powder 131 preferably has an outer surface 142 that reduces friction, and the upper surface of the substrate 105 in direct contact with the dry powder 131 preferably includes a friction enhancing coating 108. More specifically, the coefficient of friction (μ 基底-粉末 ) is preferably greater than the friction coefficient (μ) between the spreading roller 141 and the dry powder 131 辊-粉末 ). The combination of these features advantageously provides the potential to ensure continuous dry casting of dry powder 131 via counter-rotating spreading rollers 140, 141 by maintaining a minimum principal stress applied to dry powder 131 between spreading roller 140 and substrate 105 greater than or equal to zero.

[0040] In order to achieve the desired uniformity in thickness of the dry powder 131 after passing between the spreading rollers 140, 141 (i.e., the gap G along both the length and width of the substrate 105), s In order to ensure uniformity of the spreading rollers 140, 141, the spreading rollers 140, 141 are preferably manufactured and oriented relative to each other with relatively close tolerances. More specifically, each spreading roller 140, 141 preferably has a radial run-out error of less than or equal to 3.0 microns, or less than or equal to 1.0 microns after manufacturing and assembly; and the spreading rollers 140, 141 are preferably oriented so that the rollers 140, 141 exhibit a roller parallelism of less than or equal to 5.0 microns, and optionally less than or equal to 1.0 microns. As used herein, the terms "radial run-out error" and "roller parallelism" have meanings known in the art. Specifically, the term "radial run-out error" refers to the variation in the outer radius of the roller (the difference between the maximum and minimum radii); and the term "roller parallelism" refers to the variation in the distance between the center axes of rollers oriented substantially parallel to each other (the difference between the maximum distance and the minimum distance).

[0041] Reference again Figure 1, compacting rollers 150, 151 evenly compact the spread dry powder 131 (after it has passed through spreading rollers 140, 141) on the upper surface of substrate 105 and friction enhancing coating 108. Compacting rollers 150, 151 are arranged vertically one above the other and can therefore be described as an upper compacting roller 150 and a lower compacting roller 151. Each compacting roller 150, 151 has a central axis 155, a radially outer cylindrical surface 152 and an outer diameter D c , the compacting rollers 150, 151 rotate around the central axis 155 in the rotation direction 156. The compacting rollers 150, 151 are positioned so that the central axis 155 is arranged in a common vertical plane. However, in other embodiments, the central axis of the compacting rollers (e.g., the central axis 155 of the spreading rollers 150, 151) is not located in a common vertical plane. Therefore, the uppermost portion of the outer surface 152 of the lower roller 151 is directly vertically opposite to the lowermost portion of the outer surface 152 of the upper roller 150. The lower portion of the upper roller 150 directly contacts and compacts the dry powder 131 on the substrate 105, while the upper portion of the lower roller 151 directly contacts and supports the lower surface of the substrate 105. In the embodiments described herein, the compaction rollers 150, 151 can apply a compaction load of up to about 3.5 tons / cm to spread the dry powder 131 (along the line contact between the rollers 150 and the dry powder 131), and more preferably apply a compaction load in the range of 0.1 to 1.5 tons / cm to spread the dry powder 131 (along the line contact between the rollers 150 and the dry powder 131).

[0042] The outer diameter D of each compacting roller 150 , 151 c In the range of 100.0 mm to 300.0 mm. In this embodiment, the outer diameter D of the compacting rollers 150, 151 is c However, in other embodiments, the outer diameter D of the compaction rollers 150, 151 is c Each compacting roller 150, 151 rotates around its corresponding axis 155 at a uniform rotation speed. In the embodiment described herein, the rotation speed of each compacting roller 150, 151 is preferably in the range of 0.1 to 80.0 RPM. In this embodiment, the two compacting rollers 150, 151 have the same rotation speed, however, in other embodiments, the rotation speeds of the compacting rollers 150, 151 may be different.

[0043] The directions of rotation 156 of the compacting rollers 150, 151 are opposite to each other. Figure 1, the rotation direction 156 of the upper compacting roller 150 is clockwise, while the rotation direction 156 of the lower compacting roller 151 is counterclockwise. However, since the compacting rollers 150, 151 are positioned above and below the substrate 105 and the dry powder 131, respectively, the rotation direction 156 is generally in the same direction as the feed direction 106 near the substrate 105 and the dry powder 131. In particular, due to the rotation direction 156 of the upper compacting roller 150, the lower portion of the outer surface 152 of the upper compacting roller 150 that contacts the dry powder 131 moves in the same direction as the feed direction 106; and due to the rotation direction 156 of the lower compacting roller 151, the upper portion of the outer surface 152 of the lower compacting roller 151 that contacts the substrate 105 moves in the same direction as the feed direction 106. For example, as Figure 1 As shown, at the point where the outer surface 152 of the upper compacting roller 140 engages the dry powder 131, the outer surface 152 of the upper compacting roller 150 generally moves to the left, and the feed direction 106 also moves to the left; and at the point where the outer surface 152 of the lower compacting roller 151 engages the substrate 105, the outer surface 152 of the lower compacting roller 151 generally moves to the left, and the feed direction 106 also moves to the left. Therefore, the two compacting rollers 150, 151 can be described as "non-counter-rotating" relative to the feed direction 106.

[0044] The compaction rollers 150, 151 are vertically spaced a sufficient distance apart to provide a gap G measured vertically from the upper surface of the substrate 105 to the lowermost portion of the outer surface 152 of the upper compaction roller 150. c Therefore, the vertical distance between the compaction rollers 150, 151 is equal to the thickness T 105 Plus gap G c It should be understood that the gap G c The vertical thickness of the dry powder 131 compacted by the compacting rollers 140, 141 on the substrate 105 to form the electrode 101 is defined. c defines the thickness of the electrode 101. In the embodiments described herein, the gap G c , and thus the vertical thickness of the dry powder 131 after passing between the compacting rollers 150 , 151 and the thickness of the electrode 101 , ranges from 0 to 2,000.0 microns, or alternatively ranges from 20.0 microns to 200.0 microns.

[0045] Still reference Figure 1, the supply roller 110, the receiving roller 120, the lower spreading roller 141 and the lower compacting roller 151 support the substrate 105 (and the parts disposed thereon, such as the dry powder 131 and the electrode 101) via direct contact with the substrate 105. In this embodiment, an air bearing 160 is also provided to support the substrate 105 (and the parts disposed thereon, such as the dry powder 131) in a non-contact manner. The air bearing 160 also reduces the vertical vibration of the substrate 105 to allow more precise conveying of the substrate 105 (and the parts thereon). In the embodiments described herein, each air bearing 160 is configured to provide both a positive pressure air cushion 161 (higher than the ambient atmospheric pressure) and a negative pressure suction 162 (lower than the ambient atmospheric pressure) to allow frictionless support of the substrate 105 while reducing the vibration of the substrate 105 for relatively high-speed production operations. In the embodiments described herein, air bearing 160 preferably minimizes vertical vibration of the portion of substrate 105 positioned horizontally between rollers 110, 120, 140, 141, 150, 152 to less than 3.0 microns (measured vertically from the lowest point of substrate 105 to the highest point of substrate 105).

[0046] Reference now Figure 3 , an embodiment of a method 200 for manufacturing an electrode 101 on a substrate 105 is shown. The method 200 utilizes the previously described and Figure 1 The present invention is performed by the system 100 shown in FIG. 1 , and therefore, will be described with reference to the system 100 .

[0047] In this embodiment, the method 200 begins at frame 201, where a dry powder 131 is prepared. As described above, the dry powder 131 includes a plurality of nanoparticle-coated micron particles (e.g., nanoparticle-coated micron particles 193) and is "dry" (i.e., does not include any solvent and is not prepared using any solvent). Next, in frame 202, the powder applicator 130 is loaded with the dry powder 131, and in frame 203, the substrate 105 moves in the feed direction 106 via the rollers 110, 120. Now moving to frame 204, the dry powder 131 is deposited on the substrate 105 via the powder applicator 130. The substrate 105 (moving in the feed direction 106) transports the dry powder 131 through the rest of the system 100. In particular, the substrate 105 conveys the dry powder 131 from the powder applicator 130 to the spreading rollers 140, 141, then from the spreading rollers 140, 141 to the compacting rollers 150, 151, and then from the compacting rollers 150, 151 to the receiving roller 120 along the feed direction 106. Thus, the rollers 140, 141, 150, 151 may be described as being downstream of the powder applicator 130, the compacting rollers 150, 151 may be described as being downstream of the spreading rollers 140, 141 and the powder applicator 130, and the receiving roller 120 may be described as being downstream of the rollers 140, 141, 150, 151 and the powder applicator 130 with respect to the feed direction 106. During the conveyance of the dry powder 131 through the system 100, the substrate 105 is vertically supported by the rollers 141, 151 and the air bearings 160. Additionally, as previously described, the air bearing 160 is used to reduce vibrations of the substrate 105 .

[0048] Still reference Figure 3 The substrate 105 conveys the dry powder 131 between the spreading rollers 140, 141, and the spreading rollers 140, 141 spread the dry powder 131 on the substrate 105. Several features of the system 100 are specifically designed and configured to ensure that the dry powder 131 is evenly and uniformly spread to the gap G. s In particular, the system 100 includes a friction enhancing coating 108 that contacts the dry powder 131, a low friction outer surface 142 of an upper spreading roller 140 that contacts the dry powder 131, counter-rotating spreading rollers 140, 141 that move proximally to the dry powder 131 in a rotational direction 146 that is generally opposite to the feed direction 106, and high precision spreading rollers 140, 141 (manufactured and oriented relative to each other with relatively tight tolerances on radial runout error and roller parallelism) to ensure that the dry powder 131 is evenly and uniformly spread to the gap G defined by the gap G. s The desired thickness is defined. Moving now to block 206 , the substrate 105 conveys the spread dry powder 131 between compacting rollers 150 , 151 , which compact the dry powder 131 on the substrate 105 to form the electrode 101 .

[0049] exist Figure 1 In the embodiment of the system 100 shown in FIG. 1 and described above, the electrode 101 is formed on one side of the substrate 105. However, in other embodiments, the electrodes may be formed on both sides of the substrate. For example, referring now to Figure 4 , an embodiment of a system 100' for dry manufacturing electrodes for energy storage devices (such as Li-ion batteries and all-solid-state batteries) is shown. System 100' is substantially the same as system 100 previously described, except that system 100' produces continuous sheets or layers of electrode material 101 on both sides of substrate 105'. Therefore, features of system 100' that are the same as system 100 will be given the same figure numbers and will not be described in detail for the purposes of clarity and conciseness, it being understood that these common features are the same as those previously described with respect to system 100. The electrode material 101 and substrate 105' can be cut as needed to produce multiple individual electrodes for an energy storage device, and therefore, for the purposes of clarity and further explanation, each layer of electrode material 101 may also be referred to herein as electrode 101.

[0050] Still reference Figure 4 In this embodiment, the system 100' includes a supply roller 110, a receiving roller 120 horizontally spaced apart from the supply roller 110, a powder applicator 130, a pair of spreading rollers 140, 141, a pair of compacting rollers 150, 151, and a plurality of air bearings 160, each as previously described. The supply roller 110 generally provides a continuous sheet of a substrate 105' on which the electrode 101 is formed using the system 100', and the receiving roller 120 generally receives the continuous sheet of the substrate 105' and the electrode 101 formed on the substrate 105'.

[0051] The substrate 105' is similar to the substrate 105 described previously. In particular, the substrate 105' includes a conductive base 107 in the form of a sheet of conductive material and a friction enhancing coating 108 applied to the upper surface of the base 107. However, in this embodiment, the friction enhancing coating 108 is also applied to the lower surface of the base 107. In order to manufacture the electrodes 101 on both sides of the substrate 105', the substrate 105' passes through the system 100' twice. More specifically, the substrate 105' passes through the system 100' for the first time to form the electrodes 101 on the upper surface of the substrate 105', and then the substrate 105 is turned over and passes through the system 100' for the second time to form the electrodes 101 on the upper surface of the substrate 105', the upper surface of the substrate 105' being the lower surface of the substrate 105' when passing through the system 100' for the first time. The first pass of the substrate 105' through the system 100' to form the electrodes 101 on one side of the substrate 105' is the same as previously described. The second pass of the substrate 105' through the system 100' to form the electrode 101 on the opposite side of the substrate 105' is the same as previously described, except that the vertical distance between the lower spreading roller 141 and the substrate 105', the vertical distance between the lower compacting roller 151 and the substrate 105', and the vertical distance between the air bearing 160 and the substrate 105' are increased by a gap G c To accommodate the previously formed electrode 101 vertically positioned between the rollers 141, 151 and the substrate 105' and vertically positioned between the air bearing 160 and the substrate 105'.

[0052] In the manner 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 for energy storage devices such as batteries (e.g., lithium-ion batteries, solid-state batteries, etc.). Such embodiments provide the potential for several advantages over conventional systems and methods. In particular, the embodiments described herein can increase dry powder and electrode uniformity and are suitable for a wide range of electrode compositions. In addition, the use of "dry" powders to form electrodes according to the embodiments described herein can reduce manufacturing costs, manufacturing equipment footprint, and energy consumption by eliminating the need for solvent drying and recovery.

[0053] Although preferred embodiments have been shown and described, modifications thereof may be made by those skilled in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not restrictive. Many variations and modifications of the systems, devices, and processes described herein are possible and are within the scope of the present disclosure. For example, the relative sizes of the various components, the materials used to make the various components, and other parameters may be changed. Therefore, the scope of protection is not limited to the embodiments described herein, but is limited only by the appended claims, the scope of which shall include all equivalents of the subject matter of the claims. Unless otherwise expressly stated, the steps in the method claims may be performed in any order. The recitation of identifiers such as (a), (b), (c) or (1), (2), (3) before the steps in the method claims is not intended to and does not specify a particular order of the steps, but is used to simplify subsequent references to these steps.

Claims

1. A system for dry manufacturing of electrodes for energy storage devices, the system comprising: a substrate configured to move in a feed direction; a powder applicator configured to deposit a dry powder onto a surface of a substrate; at least one pair of spreading rollers, wherein the at least one pair of spreading rollers comprises an upper spreading roller and a lower spreading roller located below the upper spreading roller, wherein the upper spreading roller and the lower spreading roller are positioned downstream of the powder applicator relative to the feed direction, wherein each spreading roller has a central rotation axis and a radially outer surface, wherein the radially outer surface of the upper spreading roller is configured to directly contact and spread the dry powder on the substrate; wherein the upper spreading roller is configured to rotate proximally of the substrate and the dry powder in a rotation direction opposite to a feed direction of the substrate, and the lower spreading roller is configured to rotate in a rotation direction that is the same as the rotation direction of the upper spreading roller; and at least one pair of compacting rollers, wherein the at least one pair of compacting rollers comprises an upper compacting roller and a lower compacting roller located below the upper compacting roller, wherein the upper compacting roller and the lower compacting roller are positioned downstream of the at least one pair of spreading rollers relative to the feed direction, wherein each compacting roller has a central rotational axis and a radially outer surface, wherein the radially outer surface of the upper compacting roller is configured to directly contact and compress the dry powder to form an electrode on a surface of a substrate; Wherein the upper compacting roller is configured to rotate in a rotation direction opposite to a rotation direction of the upper spreading roller.

2. The system of claim 1, wherein the upper spreading roller is spaced a gap G above the surface of the substrate. s , and the upper compacting roller is spaced above the surface of the substrate by a gap G c , where the gap G c Smaller than the gap G s .

3. The system according to claim 2, wherein the gap G s and the gap G c Each is in the range of 0 to 2,000 microns.

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

5. The system of claim 1, wherein the substrate comprises a conductive base and a friction enhancing coating applied to the conductive base.

6. The system of claim 5, wherein the conductive base comprises a conductive foil and the friction enhancing coating comprises carbon.

7. The system according to claim 5, wherein the friction coefficient μ between the radially outer surface of the first spreading roller and the dry powder is 辊-粉末 The friction coefficient μ between the friction enhancing coating of the substrate and the dry powder is less than 基底-粉末 .

8. The system of claim 1, wherein the dry powder comprises a plurality of nanoparticle-coated microparticles.

9. The system of claim 1, further comprising an air bearing positioned below and supporting the substrate, and wherein the air bearing is configured to reduce vibration of the substrate.

10. The system of claim 1, wherein a radially outer surface of the lower spreading roller contacts and supports a substrate; wherein each spreading roller has a radial runout error of less than or equal to 3.0 microns; Wherein a central axis of the upper spreading roller and a central axis of the lower spreading roller exhibit a roller parallelism of less than or equal to 5.0 microns.

11. The system of claim 1 , wherein the dry powder comprises: Active materials; and Binder.

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

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

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

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

16. The system of claim 1, wherein the substrate has a thickness ranging from 1.0 microns to 30.0 microns.

17. A method for dry manufacturing of an electrode for an energy storage device, the method comprising: (a) depositing dry powder onto the surface of a substrate moving in a feed direction; (b) after (a), conveying the dry powder on the substrate under a first spreading roller rotating in a first rotational direction to spread the dry powder on the substrate, wherein the first rotational direction is opposite to the feed direction at a contact point between the first spreading roller and the dry powder; and (c) After (b), conveying the dry powder and substrate beneath a compacting roller rotating in a second rotational direction opposite to the first rotational direction to compress the dry powder composition and produce an electrode on the surface of the substrate.

18. The method of claim 17, wherein (b) comprises rotating the first spreading roller at a first rotational speed, and (c) comprises rotating the compacting roller at a second rotational speed, wherein the first rotational speed is in the range of 0.1 to 200.0 RPM and the second rotational speed is in the range of 0.1 to 80.0 RPM.

19. A method according to claim 17, wherein (b) includes spreading the dry powder to a first thickness measured from the surface of the substrate to the first spreading roller, and (c) includes compressing the dry powder to a second thickness measured from the surface of the substrate to the compacting roller, wherein the second thickness is less than the first thickness.

20. The method of claim 19, wherein the first thickness and the second thickness are each in a range of 0.0 micrometers to 2,000.0 micrometers.

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

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

23. The method of claim 17, wherein the first spreading roller has a radially outer surface that contacts and spreads the dry powder in (b), wherein the friction coefficient μ between the radially outer surface of the first spreading roller and the dry powder is 辊-粉末 The friction coefficient μ between the friction enhancing coating of the substrate and the dry powder is less than 基底-粉末 .

24. The method of claim 17, wherein the dry powder comprises a plurality of nanoparticle-coated microparticles.

25. The method of claim 17, further comprising: (d) supporting the substrate during (a), (b), and (c) with one or more air bearings positioned below the substrate; (e) reducing vibration of the substrate during (a), (b) and (c) with the one or more air bearings by providing both a positive pressure air cushion and a negative pressure suction force to the substrate with the one or more air bearings.

26. The method of claim 17, wherein (b) further comprises: conveying the dry powder on the substrate onto a second spreading roller rotating in a first rotational direction; contacting the substrate with a second spreading roller; wherein each spreading roller has a central rotational axis and a radially outer surface, wherein each spreading roller has a radial run-out error less than or equal to 3.0 microns, and Wherein the central axis of the first spreading roller and the central axis of the second spreading roller exhibit a roller parallelism of less than or equal to 5.0 microns.

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