Systems and methods for dry electrode manufacturing using electrically charged particles

Abstract

A method for manufacturing an electrode on a current collector includes contacting nano-particle coated micro-particles with a rubbing element to impart an electrical charge to the nano-particle coated micro-particles to form electrically charged nano-particle coated micro-particles, and electrostatically adhering to a current collector the electrically charged nano-particle coated micro-particles to form an electrode on the current collector whereby the electrically charged nano-particle coated micro-particles exhibit sufficient adhesion to the current collector to resist detachment under the force of gravity.

Description

2238-22801SYSTEMS AND METHODS FOR DRY ELECTRODE MANUFACTURING USING ELECTRICALLY CHARGED PARTICLESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of U.S. provisional patent application Serial No. 63 / 695,033 filed September 16, 2024, and entitled "Systems and Methods for Dry Electrode Manufacturing Using Charged Particles," which is hereby incorporated herein by reference in its entirety for all purposes.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.TECHNICAL FIELD

[0003] The disclosure relates generally to systems and methods for dry manufacturing electrodes for energy storage devices such as batteries (e.g., lithium ion batteries, solid- state batteries, etc.). More specifically, the disclosure relates to systems and methods that enhance adhesion of powder particles onto current collectors of the electrode to facilitate solvent free-electrode manufacturing.BACKGROUND

[0004] Dry electrode manufacturing offers a sustainable alternative to traditional solventbased methods, particularly for using polyvinylidene fluoride (PVDF) as a binder in battery production. Unlike solvent methods, which require hazardous solvents like N- Methyl-2-pyrrolidone (NMP) and energy-intensive drying processes, dry manufacturing methods eliminate solvents entirely, thereby reducing environmental impacts, production costs, and energy consumption. The dry manufacturing methods not only simplify manufacturing but also align with industry goals for greener, more efficient production processes while maintaining or even exceeding the mechanical and electrochemical performance of electrodes made by traditional wet manufacturing methods.BRIEF SUMMARY OF THE DISCLOSURE

[0005] An embodiment of a method for manufacturing an electrode on a current collector comprises (a) contacting nano-particle coated micro-particles with a rubbing element to impart an electrical charge to the nano-particle coated micro-particles to form electrically2238-22801 charged nano-particle coated micro-particles, and (b) electrostatically adhering to a current collector the electrically charged nano-particle coated micro-particles to form an electrode on the current collector whereby the electrically charged nano-particle coated micro-particles exhibit sufficient adhesion to the current collector to resist detachment under the force of gravity. In some embodiments, the method comprises (c) imparting by a tribocharger triborcharges to the nano-particle coated micro-particles to form initially electrically charged nano-particle coated micro-particles, wherein (a) comprises contacting the initially electrically charged nano-particle coated micro-particles with the rubbing element to impart an additional electrical charge to the initially electrically charged nano-particle coated micro-particles to form finally electrically charged nanoparticle coated micro-particles. In some embodiments, the method comprises (c) applying by an electrical source an electrical voltage to the rubbing element to increase an electrical voltage differential between the rubbing element and the current collector. In certain embodiments, the rubbing element comprises at least one of a rubbing roller or a plate. In certain embodiments, the rubbing element is one of electrically insulated, electrically grounded, or electrically biased. In some embodiments, the method comprises (c) contacting, following (b), the electrode with a compression roller to provide the electrode with a selected thickness. In some embodiments, at least one of the electrical charge imparted to the nano-particle coated micro-particles is positive and the rubbing element has an electropositivity that is greater than an electropositivity of the current collector, or the electrical charge imparted to the nano-particle coated microparticles is negative and the rubbing element has an electropositivity that is less than an electropositivity of the current collector. In certain embodiments, the current collector is one of electrically insulated, electrically grounded, or electrically biased. In certain embodiments, the current collector is oriented at a non-zero angle from horizontal with respect to the direction of gravity when the electrically charged nano-particle coated micro-particles are adhered to the current collector. In some embodiments, the nanoparticle coated micro-particles comprise a cathode or an anode powder mixture containing one or more of active materials, a binder, and a conductive additive.

[0006] An embodiment of a method for manufacturing an electrode on a current collector comprises (a) contacting nano-particle coated micro-particles with a surface of a tribocharger to impart an electrical charge to the nano-particle coated micro-particles to form electrically charged nano-particle coated micro-particles, and (b) electrostatically adhering to a current collector the electrically charged nano-particle coated micro-2238-22801 particles to form an electrode on the current collector whereby the electrically charged nano-particle coated micro-particles exhibit sufficient adhesion to the current collector to resist detachment under the force of gravity. In some embodiments, the method comprises (c) contacting the electrically charged nano-particle coated microparticles with a rubbing element to impart an additional electrical charge to the electrically charged nano-particle coated microparticles, and (d) applying by an electrical source an electrical voltage to the rubbing element to increase an electrical voltage differential between the rubbing element and the current collector. In certain embodiments, the rubbing element comprises at least one of a rubbing roller or a plate. In certain embodiments, the current collector is one of electrically insulated, electrically grounded, or electrically biased. In some embodiments, at least one of the electrical charge imparted to the nano-particle coated micro-particles is positive and the surface of the tribocharger has an electropositivity that is greater than an electropositivity of the current collector, or the electrical charge imparted to the nano-particle coated microparticles is negative and the surface of the tribocharger has an electropositivity that is less than an electropositivity of the current collector.

[0007] An embodiment of a system for manufacturing an electrode on a current collector comprises a powder deposition system for providing nano-particle coated microparticles, at least one of a tribocharger or a rubbing element for contacting the nanoparticle coated micro-particles to impart an electrical charge to the nano-particle coated micro-particles and thereby form electrically charged nano-particle coated microparticles, and a coating roller for directing a current collector into contact with the electrically charged nano-particle coated micro-particles whereby the electrically charged nano-particle coated micro-particles are electrostatically adherable to the current collector to form an electrode on the current collector such that the electrically charged nano-particle coated micro-particles exhibit sufficient adhesion to the current collector to resist detachment under the force of gravity. In some embodiments, the rubbing element comprises at least one of a rubbing roller or a plate. In certain embodiments, the rubbing element is one of electrically insulated, electrically grounded, or electrically biased. In certain embodiments, the current collector is one of electrically insulated, electrically grounded, or electrically biased. In some embodiments, the current collector is oriented at a non-zero angle from horizontal with respect to the direction of gravity at a location adjacent to or downstream from the at least one of the tribocharger or the rubbing element. In some embodiments, the system comprises one2238-22801 or more electrical sources electrically connected to at least one of the current collector or the rubbing element to increase an electrical voltage differential between the rubbing element and the current collector.

[0008] Embodiments described herein comprise a combination of features and characteristics intended to address various shortcomings associated with certain prior devices, systems, and methods. The foregoing has outlined rather broadly the features and technical characteristics of the disclosed embodiments in order that the detailed description that follows may be better understood. The various characteristics and features described above, as well as others, will be readily apparent to those skilled in the art upon reading the following detailed description, and by referring to the accompanying drawings. It should be appreciated that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes as the disclosed embodiments. It should also be realized that such equivalent constructions do not depart from the spirit and scope of the principles disclosed herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] For a detailed description of various exemplary embodiments, reference will now be made to the accompanying drawings in which:

[0010] FIGS. 1 and 2 are schematic side views embodiments of systems for dry manufacturing an electrodes for energy storage devices such as batteries in accordance with principles described herein;

[0011] FIGS. 3A and 3B are schematic views of exemplary micro-particles;

[0012] FIGS. 4-7 are schematic side views embodiments of systems for dry manufacturing an electrodes for energy storage devices such as batteries in accordance with principles described herein;

[0013] FIGS. 8 and 9 are flow charts illustrating embodiments of methods for manufacturing an electrode on a current collector in accordance with principles described herein;

[0014] FIGS. W and 11 are graphs depicting electrical current overtime in accordance with principles described herein;

[0015] FIGS. 12-15 are graphs depicting measured triboelectric current for different rubbing materials in accordance with principles described herein; and2238-22801

[0016] FIGS. 16-20 are images of exemplary electrodes adhered to current collectors in accordance with principles described herein.DETAILED DESCRIPTION

[0017] The following discussion is directed to various exemplary embodiments. However, one skilled in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

[0018] Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.

[0019] Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints, and open-ended ranges should be interpreted to include only commercially practical values. In addition, with respect to all ranges disclosed herein, such ranges are intended to include any combination of the mentioned upper and lower limits even if the particular combination is not specifically listed. All lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11 , 0.12, 0.13, etc.).

[0020] In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to... .” As used herein, the phrases “consist(s) of’ and “consisting of” are used to refer to exclusive components of a composition, meaning only those expressly recited components are included in the composition; whereas the phrases “consist(s) essentially of’ and “consisting essentially of” are used to refer to the2238-22801 primary components of a composition, meaning that only small or trace amounts of components other than the expressly recited components (e.g., impurities, byproducts, etc. ) may be included in the composition. For example, a composition consisting of X and Y refers to a composition that only includes X and Y, and thus, does not include any other components ; and a composition consisting essentially of X and Y refers to a composition that primarily comprises X and Y, but may include small or trace amounts of components other than X and Y. In embodiments described herein , any such small or trace amounts of components other than those expressly recited following the phrase “consist (s) essentially of’ or “consisting essentially of’ preferably represent less than 5.0 wt% of the composition, more preferably less than 4.0 wt% of the composition, even more preferably less than 3.0 wt% of the composition, and still more preferably less than 1.0 wt% of the composition. Use of broader terms such as comprises, includes, having, etc. should be understood to provide support for narrower terms such as consisting of, consisting essentially of, comprised substantially of, etc. Use of the term "optionally" with respect to any element of a claim is intended to mean that the subject element is required, or alternatively, is not required. Both alternatives are intended to be within the scope of the claim.

[0021] The term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct engagement between the two devices, or through an indirect connection that is established via other devices, components, nodes, and connections. As used herein, the terms “approximately,” “about,” “substantially,” and the like mean within 10% (i.e., plus or minus 10%) of the recited value. Thus, for example, a recited angle of “about 80 degrees” refers to an angle ranging from 72 degrees to 88 degrees.

[0022] As previously described, solvent-free, dry electrode manufacturing methods offer several advantages over conventional wet electrode manufacturing methods. A key factor in the solvent-free, dry fabrication of high-performance electrodes is the adhesion of the dry powder used to form the electrodes. Particularly, existing dry electrode manufacturing techniques involve orienting the current collector horizontally in order to evenly distribute the active material (e.g., the dry powder) onto the current collector via gravity. However, this limits application of the active material onto one surface of the current collector at a time, requiring multiple separate applications of the2238-22801 dry powder onto the current collector in order to coat each side of the current collector with the dry powder to complete the dry electrode manufacturing process of the electrode.

[0023] Accordingly, embodiments of systems and methods for dry electrode coating are described herein that do not require the current collector to be in a horizontal orientation such that each side of the current collector may be coated by an active material (e.g., a dry powder) in a single application process. In some embodiments, a vertical, solvent- free electrode manufacturing process that leverages controlled tribocharging is disclosed to enhance powder adhesion on current collectors in achieving vertical dry coating. In certain embodiments, cathode powders comprising LiNi0.eMn0.2Co0.2O2 (NMC), carbon black, and polyvinylidene fluoride (PVDF) are initially charged in a tribocharger. The initially charged dry powder may be subsequently fed into a vertical coater to be deposited onto a current collector such as, for example, carbon-coated aluminum foil. In some embodiments, the vertical coater may include of a rubbing roller, which imparts additional charges to the powder, and a coating roller, which works in concert to ensure the electrostatically deposited particles exhibit sufficient adhesion to the current collector surface to resist detachment under gravity. In certain embodiments, strong negative current flow out of the aluminum rubbing roller during the frictional interaction with the powder thereby imparting positive electrical charges to the powder particles.

[0024] In some embodiments, the active material coated onto the current collector comprises initially charged powder particles in the form of tribocharged particles. For instance, in certain embodiments, a powder may first be charged by a tribocharger to impart charges (e.g., tribocharges) to the particles of the dry powder. In certain embodiments, the material forming or defining an interior surface material of the tribocharger is selected from the tribocharge series in order to impart proper charges to the powder particles. In some embodiments, the system includes a rubbing element such as a rubbing roller for imparting an additional charge to the initially charged particles to form finally charged powder particles. In some embodiments, the material defining an outer or exterior surface of the rubbing element or roller is similarly selected from the tribocharge series. The electrostatically charged dry powder may be applied to one or both of opposing lateral sides of a current collector simultaneously with the electrically charged particles of the dry powder adhering to the one side or both sides of the current collector to form an electrode. In some embodiments, the rubbing element2238-22801 comprises a rubbing roller. In some embodiments, the rubbing element is one of electrically insulated, electrically grounded, or electrically biased. In certain embodiments, the current collector comprises an aluminum foil or a copper foil or a carbon coated aluminum foil. In certain embodiments, the current collector is oriented at a non-zero angle (e.g., an angle greater than zero and less than 180 degrees) from horizontal with respect to the direction of gravity.

[0025] In some embodiments, the system comprises a coating element such as a coating roller for coating the current collector with the finally charged powder particles. In certain embodiments, the coating element works in concert with the rubbing element to coat the current collector with the finally charged powder particles. A gap extending directly between the rubbing element and the coating element may be controlled. In embodiments where the rubbing element and coating element comprise rollers, the rotational direction of the coating roller and the rubbing roller may be individually controlled. The current collector on the coating roller may be biased, grounded or insulated. The coating roller may be biased, grounded or insulated. Additionally, the surface material of the current collector may be selected from the tribocharge series or selected based on applications.

[0026] Referring now to FIG. 1 , an embodiment of a system 10 for dry manufacturing an electrodes forenergy storage devices such as batteries (e.g., Li-ion batteries, solid-state batteries, etc.) is shown. Generally, system 10 mechanically produces a continuous sheet or layer of electrode material or simply electrode 1 by adhering a stream of solvent-free, dry powder 12 onto a current collector or substrate 20. It is to be understood that dry powder 12 is “dry,” meaning it does not include any solvent. In this exemplary embodiment, system 10 generally includes an unwinding or supply roller 30, a coating roller 40, a rubbing element 50, and a powder supply or deposition system 60.

[0027] In some embodiments, the coating roller 40 is horizontally spaced (relative to the direction of gravity) from the supply roller 30. Supply roller 30 generally provides a continuous sheet of current collector 20 on which electrode 1 is formed by system 10. In general, current collector 20 can be unwound from supply roller 30, or provided by another roller (not shown) and passed over supply roller 30 to the remainder of system 10. Supply roller 30 rotates in a rotational direction 31 about a central axis 35 to supply current collector 20 in a generally horizontal feed direction 36 through system 10. As shown in the side view of FIG. 1 , rotational direction 31 is counterclockwise and feed direction 36 is to the left. In embodiments described herein, current collector 20 is fed2238-22801 from supply roller 30 and moved in feed direction 36 at a desired feed rate or speed. For purposes of clarity and further explanation, the terms “upstream” and “downstream” are used herein to refer to positions of different components of system 10 relative to feed direction 36.

[0028] The coating roller 40 of system 10 is downstream of supply roller 30 and generally receives the continuous sheet of current collector 20 formed thereon. Current collector 20 can be wound onto coating roller 40, or passed overcoating roller 40 to another roller (not shown). Coating roller 40 comprises an outer cylindrical surface 42 and rotates in a rotational direction 41 about a central axis 45 to receive current collector 20 and electrode 15 along the generally horizontal feed direction 36. As shown in FIG. 1 , rotational direction 41 is counterclockwise, and thus, rotational directions 31 , 41 of supply roller 30 and coating roller 40, respectively, are the same. In this exemplary embodiment, as the current collector 20 passes over the coating roller 40, the direction of travel of current collector 20 changes from the feed direction 36 to a coating direction 38 that extends at a non-zero angle from the feed direction 36. In this exemplary embodiment, the coating direction 38 extends vertically or parallel the direction of gravity at approximately ninety degrees from the horizontal (e.g., orthogonal the direction of gravity) feed direction 36. In other embodiments, the angles (e.g., angles greater than 0 degrees and less than 180 degrees relative to the horizontal extending orthogonal the direction of gravity) formed between feed direction 36 and coating direction 38 may be greater or less than ninety degrees.

[0029] The rubbing element 50 of system 10 is horizontally spaced from the coating roller 40 whereby a horizontally extending gap 70 is formed between the coating roller 40 and the rubbing element 50. The minimum width of gap 70 may be controlled to adjust a thickness of the powdered coating ultimately applied to the electrode 1 . In some embodiments, the minimum width of gap 70 is approximately between 100 microns (pm) and 200 pm. However, in other embodiments, the magnitude of the minimum width of gap 70 may vary. Additionally, in this exemplary embodiment, gap 70 is vertically spaced and positioned vertically beneath the powder deposition system 60 of system 10 such that at least some of the dry powder 12 traveling along the stream thereof enter into the gap 70 formed between coating roller 40 and rubbing element 50. Further, in some embodiments, coating roller 40 and rubbing element 50 are electrically grounded. In other embodiments, rubbing element 50 may be electrically biased or electrically insulated.2238-22801

[0030] In this exemplary embodiment, rubbing element 50 comprises a roller that rotates in a rotational direction 51 about a central axis 55 to contact at least some of the dry powder 12 traveling along the stream thereof. Rotation of rubbing element 50 about central axis 55 is driven by a prime mover 56 such an actuator or motor (e.g. , an electric motor). In some embodiments, central axis 55 of rubbing element 50 may be vertically aligned with the central axis 45 of coating roller 40. As shown in FIG. 1 , rotational direction 51 is counterclockwise, and thus, rotational directions 41 , 51 of coating roller 40 and rubbing element 50, respectively, are the same. In other embodiments, rotational direction 51 may instead be counterclockwise. Additionally, given that rubbing element 50 is horizontally spaced across gap 70 from coating roller 40, the portion of coating roller 40 that defines gap 70 at a given point in time travels in a tangential direction (indicated by arrow 43 in FIG. 1 ) that is generally opposed to a tangential direction (indicated by arrow 53 in FIG. 1 ) of the portion of rubbing element 50 that also defines gap 70 at the given point in time. Alternatively, in other embodiments, these tangential directions of the portions of coating roller 540 and rubbing element 50 that define gap 70 may instead be in the same tangential direction.

[0031] In this exemplary embodiment, the rubbing element 50 defines a generally annular or cylindrical rubbing surface 52 that contacts or rubs against the stream of dry powder 12 produced by the powder deposition system 60. Particularly, the stream of dry powder 12 is released from powder deposition system 60 such that the dry powder 12 travels in a vertical (relative to the direction of gravity) release direction 13 that is parallel coating direction 38. In this manner, at least portion of the dry powder 12 travelling in release direction 13 “falls” into the gap 70 between coating roller 40 and rubbing element 50 and thereby enters into contact with the rubbing surface 52 of rubbing element 50. Rubbing contact between the rubbing surface 52 of rubbing element 50 imparts an electrical charge to the dry powder 12 to form a stream of electrically charged dry powder 12 to facilitate adhesion of the electrically charged dry powder 12 with the current collector 20 as will be discussed further herein. In some embodiments, rubbing surface 52 may be textured (e.g., at least partially covered by dimples, ridges, and / or other surface features) to maximize a surface area of the rubbing surface 52. Additionally, rubbing surface 52 may spread and / or compact an adhered layer 16 of dry powder 12 deposited on the first surface 22-1 surface of current collector 20.2238-22801

[0032] Particularly, the materials for the rubbing surface 52 of rubbing element 50 may be strategically selected with respect to the triboelectric series in view of the materials comprising the current collector 20 and / or the dry powder 12. In other words, materials having a desired electropositivity may be selected for the rubbing surface 52 where the desired electropositivity is based on the materials comprising the current collector 20 and / or the dry powder 12. In some embodiments, the dry powder 12 can be positively charged with the rubbing surface 52 of the rubbing element 50 having a greater electropositivity than the first surface 22-1 of current collector 20 whereby a negative electrical current flows from the rubbing surface 52 to positively electrically charge the dry powder 12, enhancing adhesion of the positively (e.g., electrostatically) electrically charged dry powder 12 onto the first surface 22-1 of the current collector 20. In some embodiments, to achieve the negative electrical current flow, the rubbing surface 52 of rubbing element 50 may comprise aluminum (Al) (smooth or textured in finish) while the first surface 22-1 of current collector 20 comprises carbon-coated aluminum (CB-AI). In other embodiments, the dry powder 12 can be negatively electrically charged with the rubbing surface 52 of the rubbing element 50 having a lesser electropositivity than the current collector 20 whereby a positive electrical current flows from the rubbing surface 52 to negatively (e.g., electrostatically) electrically charge the dry powder 12.

[0033] Although rubbing element 50 is depicted as a roller in FIG. 1 , the configuration of rubbing element 50 may vary in other embodiments. For example, and referring briefly to FIG. 2, another embodiment of a system 80 for dry manufacturing an electrodes for energy storage devices such as batteries is shown. System 80 includes features in common with system 10 shown in FIG. 1 , and shared features are labeled similarly. Particularly, in this exemplary embodiment, system 80 includes a rubbing element 90 in the form of a block or plate rather than a roller. The rubbing element 90 includes a contact or rubbing surface 92 that contacts or rubs against the stream of dry powder 12 produced by the powder deposition system 60. Rubbing contact between the rubbing surface 92 of rubbing element 90 imparts an electrical charge to the dry powder 12 to form a stream of electrically charged dry powder 12. Additionally, rubbing surface 92 may spread and / or compact adhered layer 16 of dry powder 12 deposited on the first surface 22-1 surface of current collector 20. Particularly, in this exemplary embodiment, may, rather than rotating about a central axis, vibrate or reciprocate in opposing directions 94. Motion of rubbing element 90 in the opposing directions 94 is driven by a prime mover 96 such an actuator or motor (e.g., an electric motor). In still other2238-22801 embodiments, systems for dry manufacturing electrodes disclosed herein may include various kinds of rubbing elements besides the exemplary roller and plate shown in FIGS. 1 and 2, respectively.

[0034] Returning to FIG. 1 , powder deposition system 60 is horizontally positioned between coating roller 40 and rubbing element 50. Thus, powder deposition system 60 is generally downstream of supply roller 30. In this exemplary embodiment, current collector 20 is a sheet of conductive material onto which electrode 1 is formed. In general, current collector 20 can be a sheet of any suitable conductive material including, without limitation, a sheet of aluminum foil or a sheet of copper foil. Additionally, current collector 20 has a thickness T 20 measured perpendicularly between opposing first and second surfaces 22-1 and 22-2, respectively, with the dry powder 12 being deposited on the first surface 22-1 thereof in this exemplary embodiment. In embodiments, described herein, the thickness T20 of current collector 20 ranges from 1 .0 micron to 200.0 micron, and alternatively ranges from 1 .0 micron to 30.0 micron. In addition, current collector 20 has a uniform width measured perpendicular to feed direction 36 between the parallel, lateral sides or edges of current collector 20.

[0035] Powder deposition system 60 generally feeds or delivers dry powder 12 that is used to form electrode 15 on current collector 20. In particular, powder deposition system 60 deposits a continuous stream of dry powder 12 onto the first surface 22-1 of current collector 20 as the dry powder 12 is contacted by the rubbing surface 52 of rubbing element 50 to impart an electrical charge to the dry powder 12 via particlesurface interactions between dry powder 12 and the rubbing surface 52 of rubbing element 50. The electrical charge imparted to dry powder 12 by rubbing element 50 facilitates the adhesion of dry powder 12 along the first surface 22-1 of current collector 20 to form the adhered layer 16 of (electrically charged) dry powder 12 as the current collector 20 travels in the coating direction 38. In some embodiments, in addition to imparting an electrical charge to the dry powder 12, rubbing element 50 may also spread and / or compact the adhered layer 16 of dry powder 12 on current collector 20 to form electrode 15 on current collector 20. Additionally, in certain embodiments, the mass feed rate of dry powder 12 onto current collector 20 by powder deposition system 60 is greater than 0.0 gram / s and less than or equal to 300.0 gram / s per 100 mm of width of current collector 20. . Although system 10 is shown configured for the continuous production of electrode 15, in other embodiments, system 10 may be configured for producing electrode 15 in discrete and separate batches.2238-22801

[0036] In embodiments in which electrode 15 is manufactured for use in Li-ion batteries, dry powder 12 includes an active material and a conductive additive (each in a powder form). Optionally, one or more solid-state electrolytes (also in a powder form) can be included in dry powder 12 when electrode 15 is manufactured for use in solid-state Li- ion batteries. Regardless of whether electrode 15 is manufactured for use in a Li-ion battery or an all-solid-state battery, dry powder 12 typically comprises at least 70 wt% active material and less than 30 wt% other components. The active material can include, without limitation, cathode materials such as lithium transition metal oxides, lithium transition metal sulfides, lithium transition metal phosphates (e.g., lithium nickel- cobalt-manganese oxide (NMC), lithium iron phosphate (LFP), lithium cobalt oxide (LCO)), sodium manganese oxide, sodium cobalt phosphate, sodium nickel phosphate, sodium iron phosphate, sodium manganese phosphate, sodium iron hexacyanoferrate, sodium manganese hexacyanoferrate, or combinations thereof; and anode materials such as graphite, carbonaceous anode materials (e.g., graphite, graphene, disordered carbon, and the like), lithium transition metal oxides, Si-based composites, or combinations thereof. In some embodiments, dry powder 12 comprises at least 90 wt% active material. In certain embodiments, including embodiments in which dry powder 12 does not include a binder, dry powder 12 comprises at least 95 wt% active material.

[0037] In some embodiments, the dry powder 12 may also include a binder. The binder can include, without limitation, a thermoplastic polymer such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), poly(vinyl alcohol) (PVA), polyethylene oxide (PEO), poly(methyl methacrylate) (PMMA), styrene-butadiene rubber (SBR), polyurethanes, ethylene vinyl acetate (EVA), acrylic polymers, polyethylene (PE), other thermoplastic polymer, or combinations thereof. The conductive additive can include, without limitation, one or more of carbon black (CB), nanoparticles, nanowires, nanotubes (e.g., carbon nanotubes (CNT)), carbon fibers, graphene, nanosilica, nanoalumina, or the like. The one or more solid-state electrolytes can include, without limitation, solid polymer electrolyte PEO / LiTFSI, lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanate (LLTO), LisInCle, LiePSsCI, silica nanofillers, AI2O3 nanofillers, LLZO nanofillers, or combinations thereof. In some embodiments, the solid- state electrolyte can function as a binder, in which case the binder may be described as comprising a solid-state electrolyte. In some embodiments, the solid-state electrolyte can function as an active material, in which case the active material may be described as comprising a solid-state electrolyte.2238-22801

[0038] In some embodiments, dry powder 12 comprises a plurality of micro-particles at least partially coated in a plurality of nano-particles (i.e. , each micro-particle is at least partially coated in a plurality of nano-particles). As used herein, the term “micro-particle” refers to a single, individual particle, which may comprise, without limitation, a single crystal particle, a polycrystal particle, a partial crystalline particle, a composite particle, or an aggregate or agglomeration of a plurality of smaller particles (e.g., a plurality of smaller single crystal particles, a plurality of polycrystal particles, a particle of an amorphous material, a plurality of nano-particles, or combinations thereof), having a size (e.g., diameter or average diameter) greater than or equal to 1 .0 micron; and the term “nano-particle” refers to a single, individual particle, which may comprise, without limitation, a single crystal particle, a polycrystal particle, a particle of an amorphous material, or a partial crystalline particle having a size (e.g., diameter or average diameter) less than 1.0 micron. Thus, in embodiments where dry powder 12 comprises a plurality of micro-particles at least partially coated in a plurality of nano-particles, the micro-particles in dry powder 12 have sizes that are typically at least 10x the size of the nano-particles.

[0039] As an example, and referring briefly to FIGS. 3A and 3B, a single micro-particle100 comprising a first material (e.g., an active material), a first plurality of nano-particles101 comprising a second material (e.g., conductive additive), and a second plurality of nano-particles 102 comprising a third material (e.g., binder) is shown in FIG. 3A. The micro-particle 100 has a size that is at least 10x the size of the first plurality of nanoparticles 101 and the second plurality of nano-particles 102. Additionally, the microparticle 100 is shown coated in the nano-particles 101 and the nano-particles 102 to form one nano-particle coated micro-particle 103. Additionally, FIG. 3B shows a single micro-particle 100 coated in the fist plurality of nano-particles 101 but not the second plurality of nano-particles 102 to form another nano-particle coated microparticle 105. A plurality of such nano-particle coated micro-particles 103 and / or 105 can be used as dry powder 12.

[0040] In general, the sizes of the various components in dry powder 12 (e.g., active material, binder, conductive additive, solid-state electrolytes, etc.) can range from nanometers (e.g., nano-particles) to tens of microns (e.g., micro-particles). For example, the active materials may have sizes ranging from 0.5 micron to 40 microns, whereas the conductive additives and some of the solid polymer electrolyte (e.g., nanofillers) can have sizes less than 1 micron. In general, any one or more of the2238-22801 individual components in dry powder 12 (e.g., active material, binder, conductive additive, solid-state electrolytes, etc.) can serve as and define the micro-particles, and any one or more of the individual components in dry powder 12 (e.g., active material, binder, conductive additive, solid-state electrolytes, etc.) can serve as and define the nano-particles. For example, in FIGS. 3A and 3B, the micro-particle 100 may comprise an active material, the first plurality of nano- particles 101 may comprise conductive additives, and the second plurality of nano-particles 102 may comprise binder.

[0041] In some embodiments, each micro-particle (e.g., each micro-particle 100) has a size ranging from 1 .0 micron to 30.0 microns and each nano-particle has a size ranging from 1.0 nm to 500.0 nm. In general, the nano-particle coated micro-particles forming dry powder 12 can be prepared by any suitable means known in the art (e.g., intensive dry mixing) and then added to powder deposition system 60 for controlled deposition on current collector 20 shown in FIGS. 1 and 2.

[0042] In addition to the active material, the binder, the conductive additive, and other optional components described above (e.g., solid-state electrolytes for solid-state Li-ion batteries), the dry powder 12 can optionally include other types of nano-particles as functional additives to fine-tune particular aspects of battery performance such as safety, energy density, integrity, rate performance, and cycle life. For instance, TiO2 nano-particles can be added in graphite (micro-particle) anode to improve rate capability and thermal stability. Further, particles or units of nanomaterials such as nanowires and / or nanotubes can be used in conjunction with nano-particles or as an alternative to nano-particles to coat the micro-particles to achieve similar effects. Examples of such other nanomaterials include hollow nano-particles, core-shell nano-particles, nano-dots, nano-tubes, nano-rods, nano-wires, nano-sheets, (graphene quantum dots, silicon nano-wires, carbon nano-tubes, silicon nano-tubes, nano-sized carbon fiber, mesoporous carbon, graphene, etc.). Any such particles or units of nanomaterials may have at least one dimension less than 1 .0 micron, and more at least one dimension less than 100 nm.

[0043] As previously described, in some embodiments, dry powder 12 comprises a plurality of nano-particle coated micro-particles (e.g., nano-particle coated microparticles 103 and / or 105). However, in other embodiments, dry powder 12 may comprise a mixture of other types of particles other than nano-particle coated micro-particles 103 and / or 105.2238-22801

[0044] Referring to FIG. 4, another embodiment of a system 110 for dry manufacturing an electrodes for energy storage devices such as batteries is shown. System 110 includes features in common with system 10 shown in FIG. 1 , and shared features are labeled similarly. Particularly, in this exemplary embodiment, system 110 includes a tribocharger 112 located vertically (e.g., with respect to the direction of gravity) between the powder deposition system 60 and the coating roller 40, and a compression roller 120 located vertically below the tribocharger 112 and horizontally spaced from the coating roller 40. In some embodiments, tribocharger 112 is horizontally aligned with the powder deposition system 60 for receiving the stream of dry powder 12 that is produced therefrom. Particularly, tribocharger 112 is configured to impart an electrical charge to the dry powder 12 before it comes into contact with the current collector 20 whereby the dry powder 12 may adhere to the first surface 22-1 of current collector 20 as the adhered layer 16 which forms the electrode 15.

[0045] In this exemplary embodiment, tribocharger 112 generally includes a body 113 that defines a fluid passage 114 for receiving the stream of dry powder 12 that is at least partially defined by an inner surface 115 of tribocharger body 113. In this manner, the stream of dry powder 12 may pass (e.g, vertically fall) continuously through the fluid passage 114 of tribocharger body 113 whereby at least a portion of the dry powder 12 contacts the inner surface 115 thereof. In other embodiments, system 110 may be configured for batch production rather than continuous production of electrode 15 with tribocharger body 113 comprising a container that receives batches of dry powder 12 within a closable or sealable internal receptacle thereof.

[0046] Tribocharger 112 also includes a prime mover 116 such an actuator or motor (e.g., an electric motor) that is configured to move (indicated by arrow 117 in FIG. 4) tribocharger body 113 relative to the stream of dry powder 12 that flows through the fluid passage 114 thereof. In some embodiments, prime mover 116 may move the tribocharger 113 in directions other than direction 117 such as, for example, horizontally. The prime mover 116 may vibrate or shake tribocharger body 113, reciprocate tribocharger body 113, rotate tribocharger body 113, and the like. The relative movement in tribocharger body 113 induced by prime mover 116 facilitates rubbing contact between dry powder 12 and inner surface 115 such that tribocharger may impart (e.g., electrostatically) an electrical charge to the dry powder 12 via particle-surface interactions therebetween whereby the electrically charged dry powder 12 may adhere2238-22801 to the first surface 22-1 of current collector 20. The inner surface 115 of tribocharger body 113 may be electrically ungrounded in some embodiments.

[0047] Similar to the rubbing element 50 described above, the materials for the inner surface 115 of tribocharger 112 may be strategically selected with respect to the triboelectric series in view of the materials comprising the current collector 20 and / or the dry powder 12. In some embodiments, the dry powder 12 may be positively electrically charged with the inner surface 115 of tribocharger 112 having a greater electropositivity as Aluminum

[0048] The compression roller 120 of system 110 spreads or compacts the electrically charged dry powder 12 to form the adhered layer 16 of dry powder 12 onto the first surface 22-1 of current collector 20, thereby forming electrode 15. Compression roller 120 has a central axis 125 about which it rotates, and comprises a radially outer cylindrical surface 122. Compression roller 120 rotates in a rotational direction 121 (shown as clockwise in FIG. 4) about its central axis 125. In this arrangement, the portion of outer cylindrical surface 122 of compression roller 120 contacting the dry powder 12 moves in the same direction as coating direction 38 Alternatively, in other embodiments, coating roller 120 may rotate in an opposing rotational direction (e.g., counterclockwise in FIG. 4) opposite the coating direction 38. The outer cylindrical surface 122 of compression roller 120 directly contacts and compacts dry powder 12 on the first surface 22-1 of current collector 20 to form electrode 15.

[0049] Referring to FIG. 5, another embodiment of a system 130 for dry manufacturing an electrodes for energy storage devices such as batteries is shown. System 130 includes features in common with system 10 shown in FIG. 1 , and shared features are labeled similarly. For instance, in this exemplary embodiment, system 130 includes both tribocharger 112 and rubbing element 50 each imparting electrical charges (e.g., each imparting positive electrical charges or negative electrical charges) to the dry powder 12 to facilitate adhesion of dry powder 12 to the first surface 22-1 of current collector 20 to thereby form the adhered layer 16 and ultimately the electrode 15. For example, tribocharger 112 may initially electrically charge the dry powder 12 to produce a stream of initially electrically charged particles (e.g., nano-particle coated microparticle 103 and / or 105) while the rubbing element 50 may impart an additional electrical charge to the initially charged particles of dry powder 12 to produce a stream of finally electrically charged particles (e.g., nano-particle coated micro-particle 103 and / or 105) with the magnitude of the electrical charge of the finally electrically charged particles (be2238-22801 it negative or positive) being greater than the electrical charge of the initially electrically charged particles. This additional electrical charging of the particles of dry powder 12 may enhance the adhesion of dry powder 12 onto the current collector 20.

[0050] Additionally, in this exemplary embodiment, system 130 includes a pair of compression rollers 140-1 and 140-2 that are vertically spaced (e.g., positioned vertically beneath) from the coating roller 40 and rubbing element 50 and horizontally spaced from each other along a common horizontal plane. Particularly, compression rollers 140-1 and 140-2 are separated by a horizontally extending gap 150 that is smaller in magnitude than the gap 70. The pair of compression rollers 140-1 and 140-2 are thus located downstream from the coating roller 40 and rubbing element 50 whereby the current collector 20 with the adhered layer 16 of dry powder 12 formed onto the first surface 22-1 thereof is continuously inserted into the gap 150 extending between compression rollers 140-1 and 140-2.

[0051] In this exemplary embodiment, rubbing element 50 uniformly coat layer 16 of dry powder 12 on the first surface 22-1 of current collector 20, and then compression rollers 140-1 and 140-2 compact (or further compact) adhered layer 16 of dry powder 12 deposited on the first surface 22-1 of current collector 20 to form electrode 15. For example, rubbing element 50 may spread the adhered layer 16 of dry powder 12 on current collector 20, and then compression rollers 140-1 and 140-2 may compact the spread adhered layer 16 of dry powder 12 onto current collector 20; or rubbing element 50 may compact adhered layer 16 of dry powder 12 on current collector 20, and then compression rollers 140-1 and 140-2 may further compact adhered layer 16 of dry powder 12 onto current collector 20.

[0052] Each compression roller 140-1 and 140-2 has a central axis 145 about which it rotates, and comprises a radially outer cylindrical surface 142. A first compression roller 140-1 rotates in a first rotational direction 141-1 (shown as clockwise in FIG. 5) about its central axis 145 while a second compression roller 140-2 rotates in an opposing second rotational direction 141-2 (shown as counterclockwise in FIG. 5) about its central axis 145. In this arrangement, the portion of outer cylindrical surface 142 of both compression rollers 140-1 and 140-2 contacting the dry powder 12 and current collector 20 move in the same direction as coating direction 38 The outer cylindrical surface 142 of first compression roller 140-1 directly contacts and compacts dry powder 12 on the first surface 22-1 of current collector 20 to form electrode 15, while the outer cylindrical surface 142 of second compression roller 140-2 supports the second surface 22-2 of2238-22801 current collector 20. In embodiments described herein, compression rollers 140-1 and 140-2 can apply a compaction load of up to about 3.5 tons / cm to compress dry powder 12 (along a line contact between first compression roller 140-1 and dry powder 12). In some embodiments, compression rollers 140-1 and 140-2 can apply a compression load ranging from 0.01 to 1 .5 tons / cm to compress dry powder 12 (along a line contact between first compression roller 140-1 and dry powder 12). Additionally, in some embodiments, following compression by compression rollers 140-1 and 140-2 the thickness (e.g., horizontal thickness extending between the first surface 22-1 of current collector 20 and an opposing, exposed outer surface thereof) of dry powder 12 and electrode 15, after passing between compression rollers 140-1 and 140-2, ranges from 0.0 to 3,000.0 micron, and alternatively ranges from 0.0 micron to 500.0 micron.

[0053] In this exemplary embodiment, system 130 additionally includes a receiving or coiling roller 160 is downstream of compression rollers 140-1 and 140-2 and generally receives the continuous sheet of current collector 20 and electrode 15 formed thereon. Current collector 20 and electrode 15 can be wound onto receiving roller 160, or passed over receiving roller 160 to another roller (not shown). Receiving roller 160 rotates in a rotational direction 165 about a central axis 165 to receive current collector 20 and electrode 15 along the generally vertical coating direction 38. Rotational direction 165 is counterclockwise, and thus, rotational directions 31 , 165 of supply roller 30 and receiving roller 160, respectively, are the same. As previously described, in some embodiments, current collector 20 is moved in feed direction 36 at a feed rate or speed ranging greater than 0.0 m / min and less than or equal to 130.0 m / min, and thus, current collector 20 and electrode 15 formed thereon are received by receiving roller 160 at that same rate.

[0054] Referring to FIG. 6, another embodiment of a system 170 for dry manufacturing an electrodes for energy storage devices such as batteries is shown. System 170 includes features in common with system 10 shown in FIG. 1 , and shared features are labeled similarly. System 170 is configured to form the adhered layer 16 of electrically charged dry powder 12 simultaneously onto both the first surface 22-1 and the opposing second surface 22-2 of current collector 20. Particularly, in this exemplary embodiment, system 170 includes a powder deposition system 172 for producing a stream of dry powder 12 (e.g., comprising nano-particle coated micro-particles 103, 105, and the like) and a pair of rubbing elements 50-1 and 50-2. Powder deposition system 172 is similar to powder deposition system 60 shown in FIGS. 1-5 except that powder deposition2238-22801 system 172 may include an opening through which the current collector 20 may travel in the coating direction 38. In this manner, the stream of dry powder 12 is released adjacent each side 22-1 and 22-2 of current collector 20.

[0055] The pair of rubbing elements 50-1 and 50-2 comprise rollers that are horizontally spaced from each other such that rubbing elements 50-1 and 50-2 are separated by gap 70. In this exemplary embodiment, rubbing elements 50-1 and 50-2 comprise rollers in which the central axes 55 of rubbing elements 50-1 and 50-2 are positioned along a common horizontal plane. In other embodiments, the configuration of rubbing elements 50-1 and / or 50-2 may vary from that shown in FIG. 6. For example, in other embodiments, rubbing elements 50-1 and / or 50-2 may comprise a block or plate (e.g., similar to rubbing element 90 shown in FIG. 2).

[0056] In this exemplary embodiment, a first rubbing element 50-1 rotates in a first rotational direction 50-1 (shown as counterclockwise in FIG. 6) about its central axis 55 while a second compression roller 50-2 rotates in an opposing second rotational direction 51-2 (shown as counterclockwise in FIG. 5) about its central axis 55. In this arrangement, the portion of rubbing surface 52 of both rubbing elements 50-1 and 50-2 contacting the dry powder 12 and current collector 20 move in the same vertically upwards direction which is opposite of the coating direction 38 of current collector 20 The rubbing surface 52 of first rubbing element 50-1 directly contacts and compacts dry powder 12 onto the first surface 22-1 of current collector 20 to form a first electrode 15 -1 on the first surface 22-1 , while the rubbing surface 52 of second rubbing element 50- 2 simultaneously directly contacts and compacts dry powder 12 onto the second surface 22-2 of current collector 20 to form a second electrode 15-2 on the second surface 22- 2.

[0057] Referring to FIG. 7, another embodiment of a system 190 for dry manufacturing an electrodes for energy storage devices such as batteries is shown. System 190 includes features in common with system 10 shown in FIG. 1 , and shared features are labeled similarly. Particularly, in this exemplary embodiment, system 190 includes a first electrical source (e.g., an electrical voltage or current source) 192 electrically connected to the current collector 20 and a second electrical source (e.g., an electrical voltage or current source) 194 electrically connected to the rubbing element 50. While system 190 is shown in FIG. 7 as including both electrical sources 192 and 194, in other embodiments, system 190 may include only first electrical source 192 or second electrical source 194.2238-22801

[0058] Electrical sources 192 and 194 of system 190 may electrically bias (either positively or negatively) the current collector 20 and / or the rubbing element 50, respectively, as desired by an operator of system 190. For instance, electrical sources 192 and / or 194 may be operated to increase a difference in voltage between the rubbing element 50 and the current collector 20 to increase or enhance the transference of electrical charge from the rubbing element 50 to the dry powder 12 and, concomitantly, the adherence of dry powder 12 to the first surface 22-1 of current collector 20 to form the electrode 15 thereon.

[0059] Referring to FIG. 8, an embodiment of a method 200 for manufacturing an electrode (e.g., electrode 15 shown in FIGS. 1-7) on a current collector (e.g., current collector 20 shown in FIGS. 1-7) is shown. At block 202, method 200 includes contacting nano-particle coated micro-particles (e.g., nano-particle coated microparticles 103 and / or 105 shown in FIGS. 3A and 3B) with a rubbing element (e.g., rubbing element 50 shown in FIG. 1 , rubbing element 90 shown in FIG. 2) to impart an electrical charge to the nano-particle coated micro-particles to form electrically charged nano-particle coated micro-particles. At block 204, method 200 includes electrostatically adhering to a current collector the electrically charged nano-particle coated micro-particles to form an electrode (e.g., electrode 15 shown in FIGS. 1 -7) on the current collector whereby the electrically charged nano-particle coated microparticles exhibit sufficient adhesion to the current collector to resist detachment under the force of gravity.

[0060] Referring to FIG. 9, another embodiment of a method 210 for manufacturing an electrode (e.g., electrode 15 shown in FIGS. 1-7) on a current collector (e.g., current collector 20 shown in FIGS. 1-7) is shown. At block 212, method 210 includes contacting nano-particle coated micro-particles (e.g., nano-particle coated microparticles 103 and / or 105 shown in FIGS. 3A and 3B) with a surface of a tribocharger (e.g., surface 115 of tribocharger 112 shown in FIG. 2) to impart an electrical charge to the nano-particle coated micro-particles to form electrically charged nano-particle coated micro-particles. At block 214, method 210 includes electrostatically adhering to a current collector the electrically charged nano-particle coated micro-particles to form an electrode (e.g., electrode 15 shown in FIGS. 1-7) on the current collector whereby the electrically charged nano-particle coated micro-particles exhibit sufficient adhesion to the current collector to resist detachment under the force of gravity.2238-22801EXAMPLES

[0061] The subject matter having been generally described, the following examples are given as particular aspects of the disclosure and are included to demonstrate the practice and advantages thereof, as well as aspects and features of the presently disclosed subject matter. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventors to function well in the practice of the present subject matter, and thus can be considered to constitute exemplary modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific aspects which are disclosed and still obtain a like or similar result without departing from the scope of the instant disclosure. It is understood that the examples are given by way of illustration and are not intended to limit the specification of the claims to follow in any manner.

[0062] A variety of tests were conducted to coat dry powder vertically onto a current collector. In an example, LiNi0.eMn0.2Co0.2O2 powder (NMC 622, BASF) were introduced with PVDF (Kynar, HSV900) and CB (Super C65) for fabricating electrodes, and carbon-coated aluminum foil, served as current collectors. PVDF, CB, and NMC powders were stored in a nitrogen-rich glovebox upon receiving. Two different cathode compositions were prepared: 96 / 2 wt% (NMC / CB) and 97 / 1 / 3 wt% (NMC / PVDF / CB). The 96 / 2 wt% powder was used to demonstrate that the coating performance was due to the tribocharge without any binder assistance during the vertical coating. Electrode powders were first mixed in a powder mixer, developing an initial surface charge. A tribocharger was then used to further adjust the triboelectric charge state of the powders through controlled mechanical agitation and particle-surface interactions.

[0063] In this example, the electrode powder was first blended in a mixer, resulting in the presence of negative charges within the mixed powder. To impart positive charges, the mixture was subsequently introduced into a tribocharger with an interior ungrounded aluminum wall, where particle-wall interactions generated the desired charge transfer.

[0064] In this example, a one-sided coater was utilized that included a rubbing roller, a coating roller, and a pair of compressions rollers. The coating roller carried and supported the current collector, which travelled downward vertically to be coated with electrode powders. The initially charged powder (by tribocharger), was introduced to the gap between the rubbing roller and coating roller. The rubbing roller was rotating in a counter-clockwise direction and the coating roller was rotating in the same direction.2238-22801The gap between rollers, the rotation speed, the material of the rubbing rollers, and the material of the current collector were selected such that the rubbing roller rubs (or slides) against the powder and impart proper charges on the powders. For example, if the powders were required to be positively charged, the current flowing out of the rubbing roller was required to be negative when the rubbing roller rotates against the powder. In this example, the rubbing roller material was more electropositive than the material of the current collector.

[0065] The rubbing roller could be grounded, biased, or insulated. However, in this example, the rubbing roller was grounded. The charged particles were then attached to the current collector as they passed the gap between the two rollers and coat on the current collector vertically. The coating roller (or the current collector) could be insulated, biased or grounded. However, in this example, it was grounded. The coated electrode was then passed through a pair of compression rollers to form the electrode vertically.

[0066] In this example, the triboelectric behavior of electrode powders was systematically investigated under different pre-charging and rubbing conditions to elucidate the influence of material properties and charge history on coating performance. Particular attention was given to the evolution of net charge during loading, rubbing, and after rub stages. A series of coating performance results were also prepared to illustrate the relationship between tribocharge magnitude and the adhesion of powder to the current collector.

[0067] Referring to FIG. 10, a graph 220 is shown presenting an exemplary time evolution of the electrical current measured during and after loading of pure NMC powder without prior tribocharging. As shown in graph 220, the powder exhibited a net negative charge immediately upon loading. A strong negative discharge peak (-15nA) was observed upon loading and sustained for an extended period, reflecting the high initial charge and limited opportunities for charge dissipation before deposition.

[0068] Referring to FIG. 11 , a graph 230 is shown indicating an exemplary triboelectric current profile of 97 / 1 / 3 powder across three stages from powder loading, rubbing, to after rubbing. After initial charging in a tribocharger, the powder became positively charged, producing a positive current during the loading stage (3.6 nA). During the rubbing stage, the current shifted to a strongly negative value (-27.5 nA), indicating substantial charging during rubbing. Intimate contact between the aluminum foil (rubbing roller) and the powder promoted triboelectric charging. Aluminum on the2238-22801 rubbing roller, being more electropositive than the coating roller (current collector which was CB-coated Al foil), negative current flowed out of the rubbing roller, which charged the powders positively. With the picoammeter registering a negative current, the measurement during rubbing was consistently negative. Additionally, once the rubbing process stopped, the current rapidly reversed to positive, reaching positive currents of 15 nA the after rubbing stage, significantly higher than the initial loading current.

[0069] Referring to FIGS. 12-15, graphs 240, 250, 260, and 270 are shown, respectively, that illustrate the measured triboelectric currents recorded during the rubbing process and immediately after rubbing, using different rubbing roller materials. Three different rubbing roller materials were evaluated: roughened aluminum foil (graph 240), aluminum foil (graph 250), and stainless steel (graphs 260 and 270). For each material, two powder preparation conditions were tested: without shaking (marked as no shake in graphs 240-270), and after shaking in an isolated tribocharger (marked as shaken in graphs 240-270).

[0070] For powders tested without shaking, rubbing against electropositive materials such as aluminum and roughened aluminum generated large negative currents during rubbing. Roughened aluminum produced the largest magnitude of negative currents, attributed to its enhanced effective contact area, which increased tribocharge generation rates. After rubbing, the currents in the no shake case typically remained slightly positive (in Al case) or slightly negative (in steel case), indicating that the powders were more positively charged as compared with the powders before rubbing.

[0071] On the other hand, powders shaken in the isolated tribocharger also showed negative current magnitudes during rubbing, and in every case the polarity shifted to positive after rubbing. This behavior suggests that shaking in the tribocharger modified the initial surface charge state of the powder, likely through repeated powder-wall and powder-powder contacts. The higher positive charges after rubbing observed in the tribocharged powders imply more efficient charging which might benefit in improving coating adhesion.

[0072] In summary, the combination of electropositive rubbing surfaces and powder preconditioning by shaking promotes more positively charged particles after rubbing, which could enhance coating performance by facilitating stronger electrostatic attraction between powder particles and the grounded current collector.

[0073] Referring to FIGS. 16-18, images 280, 290, and 300, respectively, are shown comparing the coating performance achieved with different rubbing roller materials2238-22801 whereby the adhesion strength of the deposited powder layer was evaluated through an external disturbance test on the current collector. In this evaluation, foil vibration was used to induce mechanical detachment, and the areas of coating loss are encircled in images 280-300. The rubbing materials that promoted stronger and more stable triboelectric charging during rubbing such as roughened aluminum foil (shown in image 280) and smooth aluminum foil (shown in image 290), consistently produced a good coating with higher adhesion to the CB-AI substrate. This enhancement was likely due to the greater electrostatic attraction generated during powder deposition, which improved particle adhesion and interfacial bonding. By contrast, rubbing rollers with lower charging capability, such steel (shown in image 300), yielded weaker coatings that were more prone to detachment after disturbance.

[0074] Referring to FIGS. 19 and 20, images 310 and 320, respectively, are shown to demonstrate vertical coating performance with a roughened Al at the rubbing side using 96 / 2 (CB) powder without any binder incorporation, where adhesion was entirely dependent on triboelectric interactions between the powder and the current collector. A uniform coating with a thickness of approximately 200 pm is shown in image 310, exhibiting a smooth surface and good coating layer. Following the application of mechanical vibration to the current collector (shown in image 320), some particle detachment was observed along the coating edges; however, most of the deposited powder remained intact. This result highlights that triboelectric charging during deposition can generate sufficient electrostatic attraction to achieve robust adhesion even in the absence of binders.

[0075] This example developed a tribocharging approach and apparatus to vertically coat the cathode powders on the current collector using an additional tribocharger and selecting the appropriate rubbing material to maximize the powder charging. Experimental results demonstrated that the choice of rubbing material significantly influences both the magnitude and polarity of triboelectric current, with materials such as roughened or smooth aluminum yielding superior coating performance compared to more electronegative surfaces. Furthermore, the approach achieved robust adhesion even in the absence of binder, as validated by post-deposition disturbance tests, underscoring the potential of tribocharging optimization for scalable, solvent-free electrode manufacturing.

[0076] While exemplary embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or2238-22801 teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the systems, apparatus, and processes described herein are possible and are within the scope of the disclosure. For example, the relative dimensions of various parts, the materials from which the various parts are made, and other parameters can be varied. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. Unless expressly stated otherwise, the steps in a method claim may be performed in any order. The recitation of identifiers such as (a), (b), (c) or (1 ), (2), (3) before steps in a method claim are not intended to and do not specify a particular order to the steps, but rather are used to simplify subsequent reference to such steps.

[0077] Each and every claim is incorporated into the specification as an aspect of the present disclosure. Thus, the claims are a further description and are an addition to the aspects of the present invention. The discussion of a reference herein is not an admission that it is prior art to the presently disclosed subject matter, especially any reference that may have a publication date after the priority date of this application. The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference, to the extent that they provide exemplary, procedural or other details supplementary to those set forth herein. In the event of conflict, the present specification, including definitions, is intended to control.

Claims

2238-22801CLAIMSWhat is claimed is:

1. A method for manufacturing an electrode on a current collector, the method comprising:(a) contacting nano-particle coated micro-particles with a rubbing element to impart an electrical charge to the nano-particle coated micro-particles to form electrically charged nano-particle coated micro-particles; and(b) electrostatically adhering to a current collector the electrically charged nano-particle coated micro-particles to form an electrode on the current collector whereby the electrically charged nano-particle coated micro-particles exhibit sufficient adhesion to the current collector to resist detachment under the force of gravity.

2. The method of claim 1 , further comprising:(c) imparting by a tribocharger triborcharges to the nano-particle coated micro-particles to form initially electrically charged nano-particle coated micro-particles; wherein (a) comprises contacting the initially electrically charged nano-particle coated micro-particles with the rubbing element to impart an additional electrical charge to the initially electrically charged nano-particle coated micro-particles to form finally electrically charged nano-particle coated micro-particles.

3. The method of claim 1 , further comprising:(c) applying by an electrical source an electrical voltage to the rubbing element to increase an electrical voltage differential between the rubbing element and the current collector.

4. The method of claim 1 , wherein the rubbing element comprises at least one of a rubbing roller or a plate.

5. The method of claim 1 , wherein the rubbing element is one of electrically insulated, electrically grounded, or electrically biased.

6. The method of claim 1 , further comprising:2238-22801(c) contacting, following (b), the electrode with a compression roller to provide the electrode with a selected thickness.

7. The method of claim 1 , wherein at least one of: the electrical charge imparted to the nano-particle coated micro-particles is positive and the rubbing element has an electropositivity that is greater than an electropositivity of the current collector; or the electrical charge imparted to the nano-particle coated micro-particles is negative and the rubbing element has an electropositivity that is less than an electropositivity of the current collector.

8. The method of claim 1 , wherein the current collector is one of electrically insulated, electrically grounded, or electrically biased.

9. The method of claim 1 , wherein the current collector is oriented at a non-zero angle from horizontal with respect to the direction of gravity when the electrically charged nano-particle coated micro-particles are adhered to the current collector.

10. The method of claim 1 , wherein the nano-particle coated micro-particles comprise a cathode or an anode powder mixture containing one or more of active materials, a binder, and a conductive additive.

11. A method for manufacturing an electrode on a current collector, the method comprising:(a) contacting nano-particle coated micro-particles with a surface of a tribocharger to impart an electrical charge to the nano-particle coated micro-particles to form electrically charged nano-particle coated micro-particles; and(b) electrostatically adhering to a current collector the electrically charged nano-particle coated micro-particles to form an electrode on the current collector whereby the electrically charged nano-particle coated micro-particles exhibit sufficient adhesion to the current collector to resist detachment under the force of gravity.

12. The method of claim 1 1 , further comprising:2238-22801(c) contacting the electrically charged nano-particle coated microparticles with a rubbing element to impart an additional electrical charge to the electrically charged nano-particle coated microparticles; and(d) applying by an electrical source an electrical voltage to the rubbing element to increase an electrical voltage differential between the rubbing element and the current collector.

13. The method of claim 12, wherein the rubbing element comprises at least one of a rubbing roller or a plate.

14. The method of claim 11 , wherein the current collector is one of electrically insulated, electrically grounded, or electrically biased.

15. The method of claim 11 , wherein at least one of: the electrical charge imparted to the nano-particle coated micro-particles is positive and the surface of the tribocharger has an electropositivity that is greater than an electropositivity of the current collector; or the electrical charge imparted to the nano-particle coated micro-particles is negative and the surface of the tribocharger has an electropositivity that is less than an electropositivity of the current collector.

16. A system for manufacturing an electrode on a current collector, the system comprising: a powder deposition system for providing nano-particle coated micro-particles; at least one of a tribocharger or a rubbing element for contacting the nano-particle coated micro-particles to impart an electrical charge to the nano-particle coated microparticles and thereby form electrically charged nano-particle coated micro-particles; and a coating roller for directing a current collector into contact with the electrically charged nano-particle coated micro-particles whereby the electrically charged nanoparticle coated micro-particles are electrostatically adherable to the current collector to form an electrode on the current collector such that the electrically charged nano-particle coated micro-particles exhibit sufficient adhesion to the current collector to resist detachment under the force of gravity.2238-2280117. The system of claim 16, wherein the rubbing element comprises at least one of a rubbing roller or a plate.

18. The system of claim 16, wherein the rubbing element is one of electrically insulated, electrically grounded, or electrically biased.

19. The system of claim 16, wherein the current collector is one of electrically insulated, electrically grounded, or electrically biased.

20. The system of claim 16, wherein the current collector is oriented at a non-zero angle from horizontal with respect to the direction of gravity at a location adjacent to or downstream from the at least one of the tribocharger or the rubbing element.

21. The system of claim 16, further comprising one or more electrical sources electrically connected to at least one of the current collector or the rubbing element to increase an electrical voltage differential between the rubbing element and the current collector.

Images