Coatings using discrete carbon nanotubes for energy storage and additive manufacturing.

Abstract

Novel coating compositions for use in energy storage devices and additive manufacturing are disclosed. The coating is composed of discrete carbon nanotubes, and to improve the wetting or flow of material through the pores of the carbon nanotube coating, the coating has a selected range of porosity, and optionally, the discrete carbon nanotubes have a selected surface modification. The coating has bundles or ropes of carbon nanotubes having dimensions greater than about 5 micrometers, less than about 20% by mass. The coating is a coating with an average thickness of about 5 nanometers to about 2000 nanometers and can be applied to particles or films with a diameter of less than about 1000 micrometers. Improved performance of energy storage or additive components includes, but is not limited to, higher electronic conductivity of electrodes in energy storage devices and higher electronic conductivity of components fabricated by additive manufacturing. The coating is particularly suitable for additive manufacturing of energy storage devices and electrodes fabricated using dry electrode processes.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to U.S. Provisional Patent Application No. 63 / 459,007, filed on 13 April 2023, and U.S. Non-Provisional Patent Application No. 18 / 633,960, filed on 12 April 2024, which are incorporated herein by reference.

[0002] This disclosure relates to novel compositions of discrete carbon nanotube coatings on particles or flat surfaces, for example, on films or sheets, wherein the coating has a selected range of porosity and thickness to improve sintering, wetting, or material flow through the pores of the carbon nanotube coating, and optionally has a selected surface modification in which discrete carbon nanotubes are present. Furthermore, the carbon nanotube coatings include coatings in the form of bundles or ropes of highly entangled carbon nanotubes, less than about 20% by mass, where the bundles or ropes of carbon nanotubes have at least one dimension of size greater than about 5 micrometers. These coatings provide improved performance in energy storage devices and in the additive manufacturing of energy storage devices or other articles using additive manufacturing, particularly in additive manufacturing processes using lasers. [Background technology]

[0003] Carbon nanotubes (CNTs) can be classified as monolayer, dilayer, and multilayer based on the number of wall layers. Each wall layer of a CNT can be further classified into chiral or non-chiral forms. Some of the carbon atoms in a CNT may be substituted with nitrogen atoms. Some of the wall layers may contain Stone-Wales defects, defined as seven-membered-ring-five-membered-ring pairs. CNTs are currently produced in large quantities using chemical vapor deposition reactors, producing aggregated bundles or rope-like carbon nanotubes. However, their commercial applications are very limited because they perform poorly as reinforcing fillers in the aggregated state. The use of CNTs as reinforcing or filling agents in polymer composites, or as conductive fillers, is an area where CNTs are expected to have significant utility, provided that they can be prepared as discrete carbon nanotubes. However, the use of CNTs in these applications has been hindered because it is generally impossible to reliably produce discrete or individualized CNTs.

[0004] Various methods have been developed for debunking or unbundling carbon nanotubes (CNTs) in various media. For example, CNTs can be significantly shortened by aggressive oxidation methods and then dispersed as individual nanotubes in dilute solutions. However, these tubes have a low aspect ratio that is unsuitable for high-strength composite materials. CNTs can also be dispersed as individual tubes in very dilute solutions by sonication in the presence of a surfactant. Exemplary surfactants used to disperse CNTs in aqueous solutions include, for example, sodium dodecyl sulfate or cetyltrimethylammonium bromide. In some examples, solutions of individualized CNTs can be prepared from polymer-coated carbon nanotubes. Solutions of individualized single-walled CNTs have also been prepared in very dilute solutions using polysaccharides, polypeptides, water-soluble polymers, nucleic acids, DNA, polynucleotides, polyimides, and polyvinylpyrrolidone, but these dilute solutions are not economical to use and are generally unsuitable for energy storage devices or additive manufacturing.

[0005] Additive manufacturing (AM) is a set of techniques for constructing three-dimensional objects by processing materials layer by layer. Materials commonly include, but are not limited to, crosslinkable monomers or oligomers, thermoplastics, metals, ceramics, cements, and biological tissues. AM techniques typically utilize computers, 3D modeling software (computer-aided design - CAD), hardware equipment, and supplied raw materials. After a CAD model of a part is generated, AM hardware converts data from the CAD file and deposits liquid, powder, sheet, or other forms of material in layered patterns to create the 3D object. The term AM encompasses many techniques and is synonymous with 3D printing, rapid prototyping, direct digital manufacturing, additive manufacturing, and additive fabrication. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Many materials have been used in additive manufacturing (AM), including, but not limited to, crosslinkable monomers and oligomers crosslinked by means such as radiation or heat, thermosetting and thermoplastic powders, thermoplastic filaments, and hot-melt plastic inks. However, many limitations remain in AM material properties, such as heat deformation resistance, rigidity, conductivity for shielding electromagnetic radiation or electrostatic control, heat transport, impact strength, and deformation during processing. For example, the conductivity of sintered articles can be significantly increased by using a coating of discrete carbon nanotubes on particles. In batteries, ion-active cathode and anode materials are often highly compressed particles that are bound together with a small amount of binder to form layers. Controlling the porosity of the cathode and anode layers is crucial because this porosity strongly affects the electrolyte's ability to transport ions throughout the layers. Maintaining and controlling the porosity around all particles is highly desirable, and this can be provided by the coating of the present invention. [Means for solving the problem]

[0007] A general object of the systems and methods disclosed herein is to provide novel compositions of discrete carbon nanotube coatings on particles or flat surfaces, for example, on films or sheets, wherein the coating has a selected range of porosity and thickness, and optionally the discrete carbon nanotubes have a selected surface modification, in order to improve bonding, sintering, wetting, or material flow through the pores of the carbon nanotube coating. Furthermore, the discrete carbon nanotube coatings include coatings in the form of bundles or ropes of highly entangled carbon nanotubes, less than about 10% by mass, where the bundles or ropes of carbon nanotubes have at least one dimension of size greater than about 5 micrometers. These coatings provide improved performance in energy storage devices and additive manufacturing of energy storage devices, or other articles using additive manufacturing, particularly in additive manufacturing processes using lasers. The coating compositions are designed to work in conjunction with a wide variety of battery assembly processes, as well as additive manufacturing processes and techniques. The coatings of the present invention can improve electron, ion, and heat transport in anodes and cathodes and electrolytes. In addition, the coatings of the present invention can be used to improve the strength of materials constituting batteries.

[0008] The coating can also be used with inorganic materials, for example, but not limited to, calcium carbonate, talc, magnesium carbonate, wollastonite, glass beads, glass fibers, glass flakes, fly ash, silica, dolomite, barium sulfate, aluminum hydroxide, halloysite, zinc oxide, titanium oxide, mica, and hematite. The coated inorganic fillers can be used as additives to elastomers, thermoplastics, thermosetting materials, and combinations thereof, namely monomers and polymers, and can be processed by means of extrusion, injection molding, casting, thermoforming, blow molding, rotational molding, film forming, pultrusion, and filament winding, but not limited to these.

[0009] Additive manufacturing can be used in the production of energy storage devices, namely batteries, such as, but not limited to, lithium-ion batteries and sodium-ion batteries. The battery components, including the casing, current collector, anode and cathode, separator, and gel and solid electrolytes, are all expected to be manufactured by additive manufacturing, as may be the case.

[0010] One general embodiment involves a coating of particles, strands, or flat surfaces having a thickness of about 5 nanometers to about 2000 nanometers on particles with an average diameter of less than about 1000 micrometers, wherein the coating is selected from the group of discrete carbon nanotubes.

[0011] The particles are selected from the group consisting of organic polymers and inorganic species. Organic polymers are selected from the group consisting of elastomers with a glass transition temperature of less than approximately 25°C and polymers with a glass transition temperature greater than approximately 25°C. Inorganic species are selected from the group consisting of silicon, sulfur, carbon, ceramics, metals, metal oxides, metal salts, and mixtures thereof. Examples of inorganic particles useful for lithium-ion battery cathodes include, but are not limited to, nickel-manganese-cobalt oxide and lithium iron phosphate. Ceramics are non-metallic inorganic materials.

[0012] The coating has a porosity of approximately 0.05 to 0.95 (porosity is defined as the ratio of voids or open space to the total volume of the carbon nanotube coating). The main characteristic defining pores is their size, i.e., their spatial dimensions. The pore size of a material can also be described by its pore distribution. Convenient analytical tools for measuring porosity are scanning electron microscopy or mercury porosimetry. Mercury porosimetry is based on the penetration of mercury into the porous structure of a material by applying isotropic pressure. This technique is based on Washburn's equation, which relates the applied pressure to the diameter of the pore into which mercury is introduced. Mercury porosimetry provides information on pores having a size in the range of approximately 900 microns to approximately 4 nanometers in diameter.

[0013] A further aspect of the porosity of coatings using discrete carbon nanotubes is that the pores are interconnected, allowing for more free passage of materials, such as gases and liquids, including, but not limited to, electrolytes, molten polymers, metals, and alloys.

[0014] Discrete carbon nanotubes are selected from the group consisting of single-walled carbon nanotubes, double-walled carbon nanotubes, or multi-walled carbon nanotubes, and mixtures thereof. The aspect ratio of the discrete carbon nanotubes may be unimodal or at least bimodal. At least a portion of the carbon nanotubes are longer than about 0.2 micrometers, preferably longer than about 0.5 micrometers, and more preferably longer than about 0.8 micrometers.

[0015] The discrete carbon nanotube coating covers at least about 50%, preferably at least about 75%, more preferably at least about 90%, and most preferably at least about 95% of the available particle surface area.

[0016] Coated particles may constitute only a portion of the particles, i.e., a mixture of uncoated and coated particles may be present. The proportion of coated particles to the present particles may be at least about 5% by weight, preferably at least about 10% by weight, more preferably at least about 25% by weight, even more preferably at least about 50% by weight, and most preferably at least about 75% by weight.

[0017] The discrete carbon nanotubes are preferably uniformly dispersed, with less than about 20% by mass of carbon nanotubes present in the coating in the form of bundles or ropes of carbon nanotubes with a dimensional scale larger than about 5 micrometers; more preferably, less than about 10% by mass of carbon nanotubes present in the coating in the form of bundles or ropes of carbon nanotubes with a dimensional scale larger than about 5 micrometers; even more preferably, less than about 5% by mass of carbon nanotubes present in the coating in the form of bundles or ropes of carbon nanotubes with a dimensional scale larger than about 5 micrometers; and most preferably, less than about 2% by mass of carbon nanotubes present in the coating in the form of bundles or ropes of carbon nanotubes with a dimensional scale larger than about 5 micrometers.

[0018] The composition may include a carbonaceous material selected from the group consisting of carbon black, carbon fibers, graphite, graphene, randomly layered graphene, reduced graphene, carbon nanorods, and graphene oxide. Randomly layered graphene is a multilayer graphene that has similar electrical properties to monolayer graphene due to its small interlayer interaction. In addition, the layered structure of randomly layered multilayer graphene can reduce the effects of the adhesion of charged impurities and surface roughness. The weight ratio of discrete carbon nanotubes to the carbonaceous material selected from the group consisting of carbon black, carbon fibers, graphite, graphene, reduced graphene, randomly layered graphene, carbon nanorods, and graphene oxide is in the range of about 1:99 to about 99:1. Parts made by sintering particles, powders, or strands having the coating composition have a surface resistance of less than about 10 billion ohms square, preferably less than about 10 million ohms square, more preferably less than about 10,000 ohms square, and most preferably less than about 1,000 ohms square.

[0019] The composition may include magnetic or paramagnetic materials. Electromagnetic interference (EMI) can be important in electronic equipment and telecommunications because it can, for example, damage electronic chips or cause signal amplification problems. Magnetic or paramagnetic materials can absorb electromagnetic radiation, and are particularly useful at radiation frequencies above about 2 GHz, but are not limited to these frequencies. Components fabricated by sintering particles, powders, or strands having a coating composition containing magnetic or paramagnetic materials may show an improvement of at least about 5 dB at a frequency of 2 GHz compared to a coating without magnetic or paramagnetic materials. Magnetic or paramagnetic materials may adhere to discrete carbon nanotubes.

[0020] The composition also includes a coating with a thickness of about 5 nanometers to about 2000 nanometers on particles with an average diameter of less than about 1000 micrometers, or on a surface such as a current collector in a battery, the coating being selected from the group of discrete carbon nanotubes and optionally including surface modification of discrete carbon nanotubes.

[0021] Surface modification of discrete carbon nanotubes can be performed using covalent, ionic, or hydrogen bonds of molecular entities selected from the group consisting of molecules containing oxygen, silicon, titanium, zirconium, sulfur, phosphorus, or nitrogen. Discrete carbon nanotubes may further include surface modifications selected from the group consisting of anionic, cationic, nonionic, and zwitterionic surfactants, polyvinyl alcohol, copolymers of polyvinyl alcohol and polyvinyl acetate, polyvinylpyrrolidone and its copolymers, carboxymethylcellulose, carboxypropylcellulose, carboxymethylpropylcellulose, hydroxyethylcellulose, polyetherimines, polyethers, starch, and mixtures thereof.

[0022] Surface modification is approximately 2J from the Hansen dispersion parameter value of the polymer particles or strands. 0.5 m -1.5has a value of the dispersion parameter of the Hansen solubility parameter within. The surface modification of the discrete carbon nanotubes can be miscible with the polymer particles or strands. The surface modification can also enable chemical interactions between the particle composition and the surface modification. For example, without limitation, the discrete carbon nanotubes can be oxidized to provide carboxylic acid groups, which can react with other molecules, such as, without limitation, polymers, such as polyamides or polyesters, or inorganic materials, such as, without limitation, calcium carbonate, talc, halloysite, mica, and hematite. The surface modification can be at least partially removed or partially modified during the heat treatment of the particles, for example, to sinter or bond the particles. In a ceramic where sintering can be performed at a temperature higher than the decomposition temperature of the carbon nanotubes, the coating can serve to provide sub-micrometer channels for gas transport.

[0023] There is a constant need to improve the performance-cost ratio of energy harvesting and storage devices, such as, but not limited to, batteries, capacitors, and photoelectric conversion elements. The improvement in performance can be achieved by material selection and device design, and the cost can be reduced by using lower-cost or smaller amounts of materials, device design, and manufacturing improvements. In energy storage devices such as batteries and capacitors, reducing manufacturing energy and labor consumption and increasing the electrode thickness are two effective ways to reduce manufacturing costs. For example, in the formation of electrodes for lithium-ion batteries using the conventional slurry casting method, it involves mixing an active material, such as nickel-manganese-cobalt oxide for the cathode, a polymer that binds the active material, and a conductive additive, such as carbon black, and N-methyl-pyrrolidone (NMP). After mixing for several hours, the slurry is cast onto the current collector, dried, and calendared to form the electrode. NMP is an organic solvent commonly used in cathode formation, while water is generally used for the anode where the active material is generally graphite. For both the anode and cathode, the drying process requires an oven with a temperature exceeding 120°C and a length of dozens of meters. The energy consumed in slurry preparation and coating, combined with the solvent recovery of NMP, can account for 50% of the individual device manufacturing. Therefore, solvent-free or dry processes are an attractive proposition for reducing the cost of manufacturing energy storage or harvesting devices.

[0024] There are several techniques that can create solvent-free processes for electrodes, including laser technology, high-frequency magnetron sputtering, dry spraying, electrostatic spray deposition, and mixing with additives to assist in the binding of electrode active materials and particles. The mixing of electrode active materials and polymer binders, and further processing, such as hot calendaring, is considered the most cost-effective manufacturing route and can be easily scaled up for mass production.

[0025] Polytetrafluoroethylene (PTFE) has also been demonstrated for solvent-free electrode fabrication. For example, in a published paper, Yang et al. fabricated silicon oxide anodes using PTFE and polyvinylidene fluoride (PVDF), where PTFE, PVDF, silicon oxide, and acetylene black were dry-mixed and pressed to form the final electrode [Yang, J.; Takeda, Y.; Imanishi, N.; Capiglia, C.; Xie, J.; Yamamoto, O.SiOx-based anodes for secondary lithium batteries. Solid State Ion. 2002, 152, 125-129].

[0026] U.S. Patent No. 8,072,734 discloses an inexpensive and reliable dry process-based capacitor method for producing self-supporting dry electrode films. U.S. Patent No. 8,072,734 also discloses an exemplary process for manufacturing electrodes for use in energy storage device products, comprising the steps of supplying dry carbon particles, supplying a dry binder, dry mixing the dry carbon particles and the dry binder, and dry fibrillating the dry binder to prepare a matrix for supporting the dry carbon particles as a dry material. The binder used for fibrillation is a fluoropolymer, such as polytetrafluoroethylene (PTFE). Where a high-shear process is involved, PTFE can be stretched under high shear to form fibers, which can act as a net for supporting the active material and conductive additives. After mixing the electrode component mixture under high shear, it is hot-rolled to form a self-supporting film, and finally, hot-rolling is used again to laminate it with a current collector. However, some believe that PTFE is unsuitable for lithium-ion battery anodes due to its oxidative instability when applied to the anode. The energy level of PTFE's lowest empty molecular orbital (LUMO) is relatively low, which means that PTFE readily accepts electrons and becomes electrochemically unstable in the anodic environment.

[0027] Carbon nanotubes have been found to be usable to improve cathode conductivity in conventional cathode preparation slurry processes using NMP as a solvent medium for PVDF, or in anode preparation slurry processes that conventionally use, for example, water-based slurries of graphite and silicon. U.S. Patent No. 8,808,909 describes the addition of discrete carbon nanotubes to enhance the performance of energy storage or collection devices. In the case of cathodes, a common procedure is to pass carbon nanotubes through a high-shear instrument at a concentration of less than about 4 wt% in NMP and add them to the lithium-activated cathode material together with polyvinylidene difluoride as a binder, PVDF, and additional conductive carbon black. A common formulation may be nickel-manganese-cobalt oxide (NMC) with 3 wt% PVDF, 1 wt% multi-walled carbon nanotubes, and 3 wt% carbon black added. As the slurry dries, the PVDF, carbon black, and carbon nanotubes associate, forming adhesive regions between the NMC particles and also binding the NMC particles to the aluminum current collector. As a result, in this method, the carbon nanotubes do not coat the NMC particles beyond approximately 20% of the available surface area of ​​the NMC. In addition, the void content of the PVDF-carbon black-carbon nanotube composite is 0.

[0028] The ability to more completely coat cathode and anode materials with discrete carbon nanotubes according to the present invention is considered advantageous for improving electron and ion transfer, thereby improving battery performance. While not theoretically bound, it is hypothesized that coating of discrete carbon nanotubes on the electroactive material allows for a more uniform potential gradient across the entire electrode, and therefore the battery would have a longer cycle life than a battery made without discrete carbon nanotube coating. It is even more desirable that the coating be porous, allowing the electrolyte to pass through. The discrete carbon nanotube coating may be applied to the separator film of the battery or to copper or aluminum current collectors. The discrete carbon nanotube coating can also be applied to lithium foil.

[0029] In electrode processes using n-methylpyrrolidone, surface modification of discrete carbon nanotubes that do not dissolve in n-methylpyrrolidone is used; for example, although not limited to, it is desirable that the surface modification of the carbon nanotubes be sodium carboxymethylcellulose.

[0030] In a dry electrode process for manufacturing a battery or capacitor, electroactive particles may be coated using a liquid medium, and then the coated particles may be used in the dry electrode process. [Brief explanation of the drawing]

[0031] [Figure 1] The image shows an electron microscope photograph of a dry coating of discrete oxide multilayer carbon nanotubes, demonstrating the porosity of the coating and the presence of many open ends of the discrete oxide carbon nanotubes. The magnification is 250,000x. [Figure 2]This image shows a 50,000x electron microscope image of a discrete carbon oxide nanotube coating on Vestasint 3054D powder particles. The discrete carbon nanotubes are coated with 50 wt% polyvinylpyrrolidone, with a molecular weight of 10,000 daltons. The polyvinylpyrrolidone is visible on the tube surface as small spheres with a diameter of approximately 20-40 nanometers. The magnification is 50,000x. [Figure 3] This image shows an electron microscope photograph of a 0.1 wt% coating of discrete carbon nanotubes on Vestasint 3054D. The magnification is 10,000x. [Figure 4] The thermogram shows Vestasint 3054D powder being heated to sinter the particles, then cooled and reheated. [Figure 5] A thermogram is shown of Vestasint 3054D powder with a 2 wt% discrete multilayer carbon nanotube coating, which is heated to sinter the particles, then cooled and reheated. [Figure 6] This image shows an electron microscope photograph of a discrete carbon nanotube coating on Luvosint HTN particles. The coating consists of 0.25 wt% discrete oxidized multilayer carbon nanotubes using a polyvinyl alcohol dispersant. The magnification is 20,000x. [Figure 7] This image shows an electron microscope photograph of a discrete multiwall carbon nanotube coating on Luvosint HTN particles. The coating consists of 0.5 wt% discrete oxide carbon nanotubes using a polyvinyl alcohol dispersant. To determine the coating thickness, the coating was partially removed from the powder surface of Luvosint HTN. The magnification is 20,000x. [Figure 8] This image shows an electron microscope photograph (magnification 20,000x) of a coating of discrete single-walled carbon nanotubes on silicon particles, which is used as an anode electroactive material in lithium-ion batteries. [Figure 9]This image shows an electron microscope photograph (magnification 20,000x) of a coating of discrete single-walled carbon nanotubes on nickel-manganese-cobalt oxide (BASF NMC 523) particles, which are used as a cathode electroactive material in lithium-ion batteries. [Modes for carrying out the invention]

[0032] In the following description, certain details, such as specific quantities and sizes, are described in order to provide a complete understanding of the embodiments disclosed herein. However, it will be apparent to those skilled in the art that this disclosure can be implemented without such specific details. In many cases, details regarding such considerations are not necessary to obtain a complete understanding of this disclosure and are omitted insofar as they are within the scope of the skills of those skilled in the art.

[0033] Most terms used herein are recognizable to those skilled in the art; however, where not explicitly defined, terms should be interpreted as adopting the meaning currently accepted by those skilled in the art. Where the construction of a term renders it meaningless or essentially meaningless, its definition should be adopted from Webster's Dictionary, 3rd Edition, 2009. Definitions and / or interpretations should not be incorporated from other patent applications, patents, or publications, whether relevant or not.

[0034] The functionalized carbon nanotubes of this disclosure, also called surface-modified carbon nanotubes, generally refer to any modification of the carbon nanotube types described above or below. Such modifications may involve the nanotube ends, the inner and / or outer sidewalls, or both. Modifications may include, but are not limited to, covalent bonds, ionic bonds, chemisorption, intercalation, surfactant interactions, polymer wrapping, cleavage, solvation, and combinations thereof. In some embodiments, carbon nanotubes may be functionalized before, during, and after individualization or exfoliation.

[0035] Any embodiment disclosed herein using discrete carbon nanotubes may be modified within the spirit and scope of this disclosure to replace other tubular or non-tubular nanostructures, planar nanostructures, and / or other nanostructures, for example, organic, inorganic, or mineral nanotubes. Examples of inorganic or mineral nanotubes include silicon nanotubes, boron nitride nanotubes, and carbon nanotubes having heteroatomic substitutions in the nanotube structure. Nanotubes may contain, or associate with, organic or inorganic elements, such as carbon, silicon, boron, and nitrogen. Association may occur inside or outside the inorganic or mineral nanotube via van der Waals bonds, ionic bonds, or covalent bonds to the nanotube surface. Examples of planar nanostructures include substantially planar carbon compounds, such as graphene, and similar structures composed of, or containing, silicon and boron nitride, as well as carbon structures having heteroatomic substitutions in the nanostructure. These planar nanostructures may contain or associate with organic or inorganic elements, such as carbon, silicon, boron, and nitrogen. Association can occur on one or both surfaces of the planar nanostructure via van der Waals bonds, ionic bonds, or covalent bonds to the surface of the planar nanostructure. Other nanostructures include three-dimensional carbon structures, such as fullerenes, and similar structures composed of or containing silicon and boron nitride, as well as carbon structures having heteroatom substitutions in the nanostructure. These other nanostructures may also contain or associate with organic or inorganic elements, such as carbon, silicon, boron, and nitrogen. Association can occur inside or outside the nanostructure via van der Waals bonds, ionic bonds, or covalent bonds to the surface of the nanotube.

[0036] In various embodiments, discrete, i.e., individual carbon nanotubes are disclosed, including single-walled carbon nanotubes, double-walled carbon nanotubes, or multi-walled carbon nanotubes having lengths greater than approximately 200 nanometers. The aspect ratio is defined as the length of an individual carbon nanotube divided by its diameter. In some cases, since carbon nanotubes are not linear, the effective aspect ratio can be defined as the effective length relative to the effective diameter. The effective aspect ratio is generally smaller than the actual aspect ratio of an individual carbon nanotube. To define the aspect ratio of a carbon nanotube, it is necessary to determine the length and diameter of the same carbon nanotube. In most cases, a distribution of length and diameter exists, which can be used to define the distribution of length, diameter, or aspect ratio. In single-walled carbon nanotubes, the single-walled carbon nanotubes have strong association energy along their length and readily form ropes containing many individual single-walled carbon nanotubes. The diameter of the resulting rope can be up to several micrometers in size. Therefore, the effective diameter of a single-walled carbon nanotube can be considered to be up to several micrometers in size. In another example, a bundle of carbon nanotubes has an effective aspect ratio of the composite material, where the average length of the bundle is divided by the diameter of the bundle. The curvature of the carbon nanotubes can be selected to obtain a coating of carbon nanotubes with various porosity and pore sizes.

[0037] Theoretically, fusion between two polymer particles is considered to have occurred when polymer molecules have diffused across the interparticle boundary to a distance of at least one times the polymer's radius of gyration. Practically, this minimum interparticle boundary for molten thermoplastics is typically in the range of 10 nanometers. Without delving into the thermodynamic and viscosity equations for this diffusion phenomenon with respect to temperature and pressure, it is practically known that in low-viscosity polymers in molten materials, such as nylon, this diffusion can occur rapidly, i.e., within seconds. The radius of gyration for nylon molecules is in the range of 4–5 nm. This radius of gyration value for nylon is sufficiently small compared to the average mesh or pore size of a random multi-walled carbon nanotube array, as shown in Figure 1, meaning that low-viscosity molten polymers should be able to flow through the porous mesh of discrete carbon nanotubes. Using bundles of carbon nanotubes with a bundle size larger than about 2 micrometers makes it very difficult for the polymer molten material to flow through the entire bundle. By using well-dispersed discrete carbon nanotubes, uniform coatings can be achieved on particles or strands with a coating thickness of less than about 2 micrometers. The surface of carbon nanotubes, and, if used, the modification of the carbon nanotube surface, plays a crucial role in the sintering of polymer particles or the flow of material through the carbon nanotube coating. If the thermodynamics or surface tension of the carbon nanotube surface or modified carbon nanotube surface are similar to those of the polymer particles being sintered, and at least some interconnection voids exist, then the penetration of the polymer through the coating should be less hindered than if there were a significant difference in thermodynamics or surface tension. In some cases, a dispersant on the carbon nanotubes may be selected to diffuse into the material of the particles being sintered.

[0038] Carbon nanotubes can be oxidized with an oxidizing agent to provide carboxylic acid groups, hydroxyl groups, ketones, and lactones having an overall (total) oxidation level of about 0.1 to about 15 weight percent of the carbon nanotubes, preferably about 0.5 to about 10 weight percent, more preferably about 1 to 5 weight percent, and more preferably about 1 to 3 weight percent of the carbon nanotubes. Using the TA TGA Q50 instrument, thermogravimetric analysis (TGA) to determine the weight percentage of oxygenated species on the carbon nanotubes involves the steps of taking about 7 to 15 mg of dry oxidized carbon nanotubes and heating them in a dry nitrogen atmosphere from 100°C to 700°C at 5°C / min. The weight loss percentage from 200°C to 600°C is taken as the weight loss percentage of the oxygenated species. The oxygenated species are then analyzed by Fourier transform infrared spectroscopy (FTIR), particularly at 1730 to 1680 cm⁻¹. -1 It can also be used and quantified within the wavelength range.

[0039] Carbon nanotubes can also include oxygen-containing species with molecular weights exceeding about 100 daltons, such as, but not limited to, polyethers, polyamides, polyurethanes, polyesters, and polyketones. In these cases, the amount of oxygen-containing species may be in the range of about 1 to about 80% by weight of carbon nanotubes, preferably in the range of about 1 to about 70% by weight of carbon nanotubes, more preferably in the range of about 2 to about 50% by weight of carbon nanotubes, and most preferably in the range of about 3 to about 50% by weight of carbon nanotubes. Typically, after the oxidation and shearing processes are complete, the amount of discrete carbon nanotubes is majority (i.e., multiple), and based on the total number of carbon nanotubes, it can be as much as 70, 80, 90 or even 99 percent discrete carbon nanotubes, with the remaining tubes still partially entangled in some form. It is most preferable that the nanotubes are completely converted into discrete individual tubes (i.e., 100 percent). By using carboxyl and hydroxyl groups, carbon nanotubes can be subjected to reactions with various chemical entities, such as, but not limited to, amines, silanes, isocyanates, glycidyls, anhydrides, titanates, and acylchlorides, to provide other chemical modifications.

[0040] The discrete carbon nanotubes may further contain a dispersant or surfactant bonded to the surface of the discrete carbon nanotubes ionically or covalently by adhesion. The surfactant may be a biocompatible surfactant. The surfactant molecules can be selected such that they are prevented from entering the discrete carbon nanotubes themselves, depending on the size of the surfactant molecules in the liquid medium. The selection of the minimum size of surfactant molecules that cannot enter the tube opening is related to the diameter of the tube opening and the hydrodynamic radius of the molecules in the liquid medium.

[0041] Bundle-like or rope-like carbon nanotubes can be prepared by any known means, such as chemical vapor deposition, laser ablation, and high-pressure carbon monoxide synthesis. Bundle-like carbon nanotubes can exist in various forms, including, for example, soot, powder, fibers, and buckypaper. Furthermore, bundle-like carbon nanotubes can be of any length, diameter, or chirality. Carbon nanotubes can be metallic, metalloid, semiconductor, or nonmetallic, based on their chirality and the number of lamination walls. Examples of discrete oxide carbon nanotubes include single-walled carbon nanotubes, double-walled carbon nanotubes, or multi-walled carbon nanotubes, and combinations thereof. Those skilled in the art will recognize that some of the specific embodiments of the present invention exemplified using certain types of carbon nanotubes can be equivalently carried out within the spirit and scope of this disclosure using other types of nanotubes, such as those containing boron, nitrogen, or silicon atoms. However, controlling the desired structure of multiple discrete carbon nanotubes requires specific control of the chemical structure, thermal, and mechanical energy, which vary according to the starting structure of the carbon nanotubes.

[0042] The specific control for forming carbon nanotubes in this invention involves incorporating a portion of a structure called a Stone-Wales defect, which rearranges the six-membered rings of graphene into seven-membered-five-membered-ring pairs that fit within the six-membered-ring lattice of condensed benzene rings that constitute the laminar wall of the carbon nanotube. These Stone-Wales defects are useful in creating sites with higher bond strain energy to more easily oxidize the laminar wall of graphene or carbon nanotube. These defects and other types of condensed ring structures may also promote bending or curvature along the length of the carbon nanotube.

[0043] Stone-Wales defects are considered more common at the end caps where the curvature of the laminar walls of carbon nanotubes is greater. During oxidation, the ends of carbon nanotubes may become open, and these open ends may result in more advanced oxidation than along the laminar walls. More advanced oxidation at the tube ends, and therefore higher polarity or hydrogen bonding, is thought to help increase the average profile length to end-to-end distance ratio when the tubes are in a low-polarity medium, such as oil. The ratio of profile length to end-to-end distance can be favorably controlled by the degree of thermodynamic interaction between the tube and the medium. Surfactants and electrolytes can also be usefully used to modify the thermodynamic interaction between the tube and the selected medium. Alternative means of influencing the ratio of profile length to end-to-end distance include the use of inorganic or ionic salts and organic-containing functional groups that can adhere to or come into contact with the tube surface.

[0044] Carbon nanotubes can be obtained from various sources, such as CNano Technology, Nanocyl, Arkema, OcSiAl, LG Chem, and Kumho Petrochemical, in the form of bundles, highly entangled aggregates, or ropes. Carbon nanotubes are prepared using metal catalysts containing elements such as iron, aluminum, or cobalt, and may retain a considerable amount of catalyst, about 5 weight percent or more, associated or trapped within the carbon nanotubes. These residual metals can be harmful in applications such as thermoplastic molding compounds (where the metal accelerates the thermal decomposition of the polymer) or drug delivery, processing, imaging, and / or diagnostics (as such residual metals may be biocompatible). Furthermore, during the oxidation of carbon nanotubes, these divalent or polyvalent metal ions may associate with carboxylic acid groups on the carbon nanotubes, hindering the discretization of the carbon nanotubes during subsequent dispersion processes. Preferably, the carbon oxide nanotubes contain a residual metal concentration of less than about 25,000,000 parts per million (ppm), preferably less than about 5,000,000 parts per million. The metal composition and concentration can be conveniently determined using energy-dispersive X-ray spectroscopy or thermogravimetric analysis.

[0045] An example of a method for producing discrete carbon nanotubes with targeted oxidation is as follows: A mixture of 0.5% to 5% by weight, preferably 3% by weight, of carbon nanotubes is prepared using CNano-grade Flotube 9000 carbon nanotubes and nitric acid. CNano Flotube 9000 carbon nanotubes are multi-walled carbon nanotubes with an average diameter of 13 nm. The acid may be a mixture of sulfuric acid and nitric acid. Preferably, the initial nitric acid concentration is over 65% nitric acid. Other oxidizing media, such as but not limited to potassium permanganate or hydrogen peroxide, may also be used. The as-received CNano Flotube 9000 has a morphology similar to tangled wool balls. The mixture of nitric acid and carbon nanotubes is heated to 70-90°C for 2-4 hours with stirring. The formed oxidized carbon nanotubes are then isolated from the acid mixture. The oxidized carbon nanotubes are mainly in the form of tangled bundles. To isolate carbon oxide nanotubes, several methods can be used, but are not limited to centrifugation, filtration, mechanical compression, decantation, and other solid-liquid separation techniques. The carbon oxide nanotubes are then washed with an aqueous medium, such as water, preferably deionized water, to a pH of 3–4 to remove residual acid. The carbon nanotubes are then suspended in water at a concentration of about 0.5% to about 4% by weight, preferably about 1.5% by weight. 8 Joules / m 3The solution is subjected to strong destructive forces generated by shear (turbulence) and / or cavitation using process equipment capable of generating an energy density of . Equipment that satisfies this specification includes, but is not limited to, ultrasonic processors, cavitators, mechanical homogenizers, pressure homogenizers, and microfluidizers. Typically, based on a given starting amount of entangled carbon nanotubes in the as-received and as-prepared states, multiple discrete oxidized carbon nanotubes are produced from this process, based on the total number of nanotubes rather than the total weight of the nanotubes, preferably at least about 60%, more preferably at least about 75%, most preferably at least about 95%, and as high as 100%, with a small number of tubes, usually very few, remaining entangled, i.e., substantially unindividualized. As those skilled in the field of nanotubes will understand, since at least around 2010, “multiple” has been used in the art to mean more than any other. That is, for example, a typical sample may contain more discrete nanotubes than when aggregated as bundles or ropes. Multiple discrete oxidized carbon nanotubes may be those in which the amount of oxidized discrete carbon nanotubes exceeds approximately 50% based on the total number of carbon nanotubes present. If desired, oxidation, such as oxidation with an acid, may be carried out in the presence of a high-energy mixer to increase the weight fraction of oxidized discrete carbon nanotubes before filtration and washing. Furthermore, after the acid is removed, the catalyst residue initially present in the carbon nanotubes during production is reduced.

[0046] Obtaining discrete single-walled carbon nanotubes (WW) is more difficult than obtaining discrete WW carbon nanotubes (WW) because they need to be de-rope-bound. A convenient method for obtaining discrete WW carbon nanotubes is to utilize surface modification of WW carbon nanotubes, with or without high-energy dispersion techniques. For example, oxidized discrete WW carbon nanotubes can be obtained by treating a suspension of 0.2 wt% WW tubes (OCSiAl, Tuball) in 90% concentrated nitric acid at 90°C for 3 hours while sonicating with an ultrasonic probe. After removing the acid by filtration and washing to a pH of less than approximately 4, the oxidized WW carbon nanotubes can be dispersed in water using a surfactant, such as sodium carboxymethylcellulose, in a weight ratio of surfactant to discrete WW carbon nanotubes, with a porosity of greater than approximately 0.05 and less than approximately 0.95 in the dry coating.

[0047] Powder bed fusion is one of seven additive manufacturing processes that uses either a laser, heat, or electron beam to melt and fuse materials together to form three-dimensional objects. Powder bed fusion encompasses various techniques, such as direct metal laser sintering (DLMS), selective laser fusion (SLM), electron beam fusion (EBM), selective laser sintering (SLS), multi-jet fusion (MJF), selective thermal sintering (SHS), and selective absorption fusion (SAF). All of these methods create 3D objects by fusing / melting powdered feedstock.

[0048] Polymer powder bed melting (also known as laser sintering or LS) uses a laser to fuse thin layers of powdered polymer deposited across a construction area by leveling rollers or blades. A typical LS process proceeds as follows: Control software slices a CAD model of the component to be constructed into individual cross-sectional layers. The construction platform descends by the thickness of one layer. A powder feeder is indexed upwards and supplies the powder. Rollers or blades collect a portion of the raw material powder from the feed chamber and deposit it on the construction platform to form a smooth layer. The laser scans the cross-section of the component, selectively melting the powdered polymer. Parts of the powder bed not irradiated by laser energy remain powder. The construction chamber is moved down by the thickness of one layer. The powder feeder moves upwards to bring in the next powder layer, and this process is repeated until construction is complete. The component is removed from the powder bed, and any unsintered powder is brushed off.

[0049] Common materials used in polymer powder bed melting are polyamides (nylon 11 and 12) available from 3DChimera or Evonik Industries. Other commercially available materials include, but are not limited to, polyether block amides (PEBA), thermoplastic polyurethanes (TPU), thermoplastic elastomers (TPE), polypropylene (PP), and high-temperature polyaryl ether ketones (PAEK), including polyether ether ketones (PEK), PEEK, and polyether ketones (PEK), available from Arkema. These polymers are available in powder form from Formlabs. These polymers may also contain other particles known as fillers to improve specific properties, such as stiffness. Particles or fillers in polymers include, but are not limited to, carbon black, graphene, graphene oxide, reduced graphene oxide, carbon nanotubes, carbon nanorods, glass fibers, glass flakes, glass powder, mineral fillers, and carbon fibers.

[0050] Multi-Jet Fusion (MJF) is a powder bed melting process technology introduced by HP in 2016. In the MJF process, a machine deposits a layer of powdered feed material onto a construction platform, and an inkjet printhead moves across the powder, depositing a fusing agent and a detailing agent on top of it. An infrared (IR) heating unit then moves across the powder bed. Powder exposed to the fusing agent melts, while powder exposed to the detailing agent remains unchanged. At the end of construction, the entire powder bed is transferred to a separate processing station where unfused powder is removed by vacuum. MJF-compatible materials include polyamides 11 and 12, polypropylene, thermoplastic polyurethane (TPU), and thermoplastic polyamide elastomers (TPA).

[0051] Selective thermal sintering (SHS) is an additive manufacturing (AM) process that uses a thermal printhead to solidify powder layer by layer to create 3D objects. In SHS, the powdered feed material is heated to just below its melting point and then spread onto a construction platform using rollers. The thermal printhead moves across the construction platform, melting the cross-sectional layers of the part. After each layer is complete, the construction platform moves down by the thickness of one layer, depositing a new layer of powder on top of the previously fused layers. This process is repeated until the part is complete. The finished part is removed from the construction chamber, and any unused powder can be reused.

[0052] Selective absorption melting is a polymer powder bed melting process that uses a piezoelectric print head to deposit a highly absorbent fluid onto a powder bed to define the region of a 3D object. The powder bed is then exposed to infrared energy, and the portion of the powder bed containing the highly absorbent fluid absorbs the IR energy, selectively fusing and forming a layer. Currently, polyamides 11 and 12 are used as SAF materials.

[0053] Compound-based additive manufacturing (CBAM) is another additive manufacturing process that uses powder as a feedstock. This is fundamentally different from other powder-based technologies. CBAM uses carbon fiber or glass fiber sheets and powder to form sheet fiber-reinforced parts. The process begins by depositing long fiber sheets of carbon or glass fibers onto a construction platform. Using a transparent bonding fluid and thermal inkjet technology, layers of the part are deposited onto the fiber sheet. Next, polymer powder is deposited on top of that, adhering to the printing fluid and the fiber sheet below. Excess powder is removed and recycled back into the machine, leaving only the powder-coated layers. This process is repeated for all subsequent layers. Once all layers have been deposited, the part is heated under load to the melting point of the polymer. The molten polymer particles envelop the fibers, fusing the layers together. The unbonded portions of the sheet fibers are then passed through mechanical or chemical processes to expose the final part. Polymers, such as PEEK and polyamide 12, are currently used as matrix materials in the CBAM process.

[0054] Powders or strands for additive manufacturing of articles can be coated with the discrete carbon nanotube composition of the present invention by means of preparing a slurry of powder and a dispersion of discrete carbon nanotubes in a liquid medium, followed by drying, or by spraying the dispersion of discrete carbon nanotubes in a liquid medium onto the powder or strands and drying. Preferably, coating conditions, such as the amount of powder in the slurry and the concentration and temperature of the discrete carbon nanotubes, are selected to control the quality of the coating, the amount of coverage of the particle or strand surface by the discrete carbon nanotubes, and the thickness of the dried coating. In particular, it is desirable to prevent a significant amount of powder aggregation from occurring during the coating process. By maintaining the porosity within the discrete carbon nanotube coating, interparticle adhesion during the drying process can be better controlled.

[0055] Electroactive materials are materials used to store or provide energy for the purpose of energy storage or energy collection. Examples of electroactive materials for lithium-ion batteries, but not limited to, include transition metal oxides, transition metal salts, silicon, silicon oxide, tin, graphite, hard carbon, gallium, germanium, electroactive ceramics, sulfur, graphene, graphene oxide, lithium, and titanium dioxide. A common electroactive material for the cathode of lithium-ion batteries is nickel-manganese-cobalt oxide, or NMC.

[0056] A method for preparing electrodes for a battery or capacitor may include mixing an electrical active material with the composition of the present invention, and subsequently calendering the mixture to form a self-supporting film. In some examples, additional polymers, sometimes called binders, such as, but not limited to, polyvinylidene difluorolide, polytetrafluoroethylene, acrylonitrile rubber, polyacrylic acid, styrene-butadiene, and carboxymethylcellulose, may be used to improve the bonding of the particles themselves or to the current collector.

[0057] A suitable additive manufacturing process for fabricating energy storage devices involves binder ejection, in which metal or polymer powders coated with discrete carbon nanotubes are bound layer by layer with a fluid, the fluid itself may consist of other polymers in a solvent or water, and optionally discrete carbon nanotubes.

[0058] One embodiment includes a coating with an average thickness of about 5 nanometers to about 2000 nanometers applied to particles with an average diameter of less than about 1000 micrometers, or to a curved or flat surface, wherein the coating is selected from the group consisting of discrete carbon nanotubes. Preferably, the coating selected from the group consisting of discrete carbon nanotubes has an average thickness of about 5 to 1000 nm, more preferably about 5 to 500 nm.

[0059] Another embodiment includes a coating with an average thickness of about 5 nanometers to about 2000 nanometers, wherein the carbon nanotubes further include portions of unbundled or rope-like carbon nanotubes. Preferably, the portions of unbundled or rope-like carbon nanotubes have bundle or rope dimensions of less than about 100 micrometers, more preferably less than about 50 micrometers, even more preferably less than about 10 micrometers, and most preferably less than about 5 micrometers. The mass of the portions of unbundled or rope-like carbon nanotubes relative to the mass of all carbon nanotubes in the coating is less than about 20%, preferably less than about 10%, more preferably less than about 5%, and most preferably less than about 1%. The portions and sizes of the unbundled or rope-like carbon nanotubes are selected to maintain an average coating thickness of less than about 2000 nanometers.

[0060] In some embodiments, the coating is applied to particles with an average diameter of less than approximately 1000 micrometers, preferably less than 200 micrometers, more preferably less than 50 micrometers, and most preferably less than 20 microns. In some embodiments, the particles are substantially spherical. In some embodiments, the particles are hollow. In some embodiments, the particles have an irregular shape. In some embodiments, the particles have a dumbbell shape. In some embodiments, the particles are strands or fibers. In some embodiments, the coating is applied to continuous polymer strands, for example, strands produced by polymer extrusion, but not limited to these. In some embodiments, the particle shape is plate-like.

[0061] In a further embodiment, the coating is applied to particles so that at least about 25% of the particle surface is coated, preferably at least about 50% of the particle surface is coated, more preferably at least about 75% of the particle surface is coated, and most preferably at least about 90% of the particle surface is coated.

[0062] In some embodiments, discrete carbon nanotubes are selected from the group consisting of single-walled tubes, double-walled tubes, multi-walled tubes, or combinations thereof.

[0063] In further embodiments, the particles may comprise an organic polymer. In some embodiments, the particles may be non-organic. In some embodiments, the organic polymer may comprise elastomers with a glass transition temperature of less than about 25°C and polymers with a glass transition temperature greater than about 25°C. The polymer may be linear molecules, branched molecules, homopolymers, random copolymers, block polymers, or combinations thereof. The polymer may be thermoplastic or thermosetting. The polymer may be in the form of fine particles, strands, films, or sheets having curved or flat surfaces.

[0064] In some embodiments, the particles are magnetic or paramagnetic. Magnetic or paramagnetic particles can be prepared using metals and / or alloys having elements selected from the group consisting of iron, chromium, aluminum, uranium, platinum, copper, cobalt, lithium, nickel, neodymium, oxygen, palladium, manganese, tin, molybdenum, and samarium, as well as mixtures thereof.

[0065] In some embodiments, the coating of discrete carbon nanotubes includes magnetic or paramagnetic species. Preferably, the magnetic or paramagnetic species have an average diameter of less than about 10 micrometers, more preferably less than about 5 micrometers, and most preferably less than about 1 micrometer. Furthermore, if present, magnetic or paramagnetic particles are present in the coating of discrete carbon nanotubes in a weight fraction of more than about 0.1, preferably more than about 0.25, more preferably more than about 0.5, and most preferably more than about 0.75 of the coating.

[0066] The coating of discrete carbon nanotubes can be applied to particles of gel electrolytes or elastomers to improve the handling of the gel electrolyte or elastomer. For example, but not limited to, droplets of gel electrolyte can be coated with discrete carbon nanotubes to incorporate fluid particles into electrodes of energy storage devices. The coated gel electrolyte can be added to an electroactive material in a specific proportion, after calendering or pressing, allowing the gel electrolyte to penetrate the electroactive material. Similarly, solid polymer electrolytes can be coated with the discrete carbon nanotubes of the present invention and, when mixed with an electroactive material, can be thermally compressed to obtain a continuous medium of polymer electrolyte. The coated electrolyte particles can be part of a dry electrode process.

[0067] The dry electrode process is a process in which no solvent is used during the fabrication of battery electrodes. Typical solvent or liquid processes for preparing cathodes involve drying a slurry of electroactive particles, such as, but not limited to, nickel-manganese-cobalt oxide, n-methylpyrrolidone, and polyvinylidene difluoride as a binder.

[0068] The inorganic particles are selected from the group consisting of silicon, sulfur, carbon, ceramics, metals, metal oxides, metal salts, and mixtures thereof. The electroactive material is preferred for energy storage devices. Useful inorganic particles for the cathode of lithium-ion batteries include, but are not limited to, sulfur, nickel-manganese-cobalt oxide, and lithium iron phosphate. Useful inorganic particles for the anode include, but are not limited to, silicon, lithium, graphite, graphene, and titanium dioxide.

[0069] In some embodiments, the coating may have a porosity of about 0.05 to about 0.95 (porosity is defined as the void ratio or the ratio of open space in the coating to the total volume of the coating). In surface-modified discrete carbon nanotubes, porosity can be increased by removing some or all of the surface modification during the process of assembling the particles into an article. For example, polymer dispersants for coating discrete carbon nanotubes can be removed by thermal means or by the electrolyte of a battery.

[0070] In further embodiments, some of the carbon nanotubes are longer than about 0.2 micrometers, preferably longer than about 0.5 micrometers, and more preferably longer than about 0.8 micrometers. A length distribution in which some of the discrete carbon nanotubes are longer than 50% of the average length is also preferred.

[0071] In another embodiment, the aspect ratio of the discrete carbon nanotubes can be unimodal, bimodal, or multimodal.

[0072] In yet another embodiment, the composition may include a carbonaceous material. In some embodiments, the carbonaceous material may be selected from the group including carbon black, carbon fibers, graphite, graphene, reduced graphene, randomly layered graphene, and graphene oxide. The weight ratio of discrete carbon nanotubes to the carbonaceous material selected from the group including carbon black, carbon fibers, graphite, graphene, reduced graphene, randomly layered graphene, and graphene oxide is in the range of about 0.1:99.9 to about 99.9:0.1. Preferably, the ratio is about 0.25:1 to 99.9:0.1, more preferably about 0.5:1 to about 99.9:0.1, and most preferably 0.75:1 to 99.9:0.1.

[0073] In yet another embodiment, the coating comprises discrete carbon nanotubes dispersed on particles, strands, films, or sheets in the form of bundles or ropes of entangled carbon nanotubes having a mass of less than about 20% of the coating, wherein the bundles or ropes of carbon nanotubes have at least one dimension of greater than about 5 micrometers. Preferably, the mass of the coating in the form of bundles or ropes of entangled carbon nanotubes, wherein the bundles or ropes of carbon nanotubes have at least one dimension of greater than about 5 micrometers, is less than about 10% by weight of the carbon nanotubes, more preferably less than about 5% by weight. Even more preferably, the mass of the coating in the form of bundles or ropes of entangled carbon nanotubes, wherein the bundles or ropes of carbon nanotubes have at least one dimension of greater than about 2 micrometers, is less than about 10% by weight of the carbon nanotubes, most preferably less than about 5% by weight.

[0074] In another embodiment, the coating composition may include surface modification of discrete carbon nanotubes. Surface modification may include functionalizing the surface of the carbon nanotubes to improve the ability of the coated particles to sinter or bond. In some embodiments, modification may include functionalizing the surface of the carbon nanotubes to improve the ability of the coated particles to laser sinter or bond.

[0075] In some embodiments, the surface modification is attached to the surface of the discrete carbon nanotube by covalent, ionic, or hydrogen bonds. In some embodiments, the compositions disclosed herein further include discrete carbon nanotubes having at least one surface modification selected from the group of molecules containing oxygen, silicon, titanium, zirconium, sulfur, phosphorus, or nitrogen.

[0076] In some embodiments, the surface modification is selected from the group of molecules consisting of anionic, cationic, nonionic, and zwitterionic surfactants, polyvinyl alcohol, copolymers of polyvinyl alcohol and polyvinyl acetate, polyvinylpyrrolidone and its copolymers, carboxymethylcellulose, carboxypropylcellulose, carboxymethylpropylcellulose, hydroxyethylcellulose, polyetherimines, polyethers, starch, and mixtures thereof.

[0077] In some embodiments, the surface modifications disclosed herein result in a value of approximately 2 J from the dispersion parameter of the Hansen solubility parameter of the polymer particles or film. 0.5 m -1.5 The Hansen solubility parameter has a dispersion parameter value within [value]. In some embodiments, the surface modification is miscible with the polymer constituting the particles or film. In some embodiments, the surface modification allows for chemical interactions between the particle composition and the surface modification.

[0078] Some embodiments involve selecting a composition for surface modification of discrete carbon nanotubes, where the surface modification can be at least partially removed or partially modified during sintering or bonding of the particles for usability. For example, a dispersant for discrete carbon nanotubes may be selected such that the dispersant is soluble in the electrolyte of the energy storage device. This increases the permeability of the electrolyte through the coating.

[0079] In another embodiment, the surface-modified portion is selected so as not to provide a continuous film between the discrete carbon nanotubes. The surface-modified portion may be selected such that its volume fraction is less than about 0.8 of the total volume of the discrete carbon nanotubes and the surface-modified portion, preferably less than about 0.6 of the total volume of the discrete carbon nanotubes and the surface-modified portion, more preferably less than 0.4 of the total volume of the discrete carbon nanotubes and the surface-modified portion, and most preferably less than about 0.2 of the total volume of the discrete carbon nanotubes and the surface-modified portion.

[0080] In another embodiment, a component made by sintering or bonding coated particles, strands, or films has a surface resistance of less than about 10 billion ohms square, preferably less than about 10 million ohms square, more preferably less than about 10,000 ohms square, and most preferably less than about 1,000 ohms square.

[0081] In another embodiment, the discrete carbon nanotube coating is on a particle, and the particle is submicrometer in size in at least one dimension.

[0082] In another embodiment, particles coated with discrete carbon nanotubes are mixed with uncoated particles. Preferably, the weight ratio of coated particles to uncoated particles is greater than about 0.1, more preferably greater than about 0.25, even more preferably greater than about 0.5, and most preferably greater than about 0.75.

[0083] In another embodiment, the coated particles are assembled using a dry or liquid electrode process to produce electrodes for an energy storage or collection device.

[0084] In some embodiments, parts fabricated using the coatings of the present invention result in parts with improved properties, such as, but not limited to, mechanical, thermal, electrical, magnetic, and chemical properties, as well as improved processing properties, such as, but not limited to, greater laser energy absorption, increased particle flowability, and higher unfired (green) strength. [Examples]

[0085] Example 1.

[0086] Coating of Vestasint 3045D, an elastomer block polymer of nylon 12 and poly(tetramethylene oxide).

[0087] The polymer structure of Vestasint 3045D is thought to consist of a sub-block polymer phase of nylon 12, whose domains are crystallized by approximately 20-30 wt% nylon 12, and a block polymer phase of poly(tetramethylene oxide) that may also have some degree of crystallinity. The elastomeric behavior of articles made from Vestasint 3045D is derived from the poly(tetramethylene oxide) in the main part, which has a glass transition temperature of less than -50°C and is effectively crosslinked by nanoscale domains of semi-crystalline nylon 12.

[0088] Dispersion of oxidatively dispersed multilayer carbon nanotubes by polyvinylpyrrolidone (PVP).

[0089] Discrete oxide multilayer carbon nanotubes were prepared using CNano Flotube 9000 at a reaction temperature of 90°C for 2.5 hours with nitric acid (65% nitric acid concentration), followed by filtration to remove the acid and washing with deionized water to pH 3.5. Next, the oxide carbon nanotubes were subjected to vigorous mixing in a slurry with water to obtain discrete oxide carbon nanotubes. The amount of oxidation species in the functionalized carbon nanotubes was determined to be 2.3 wt% using the TGA method described in detail earlier. Figure 1 shows an electron microscope image of a dried sample of discrete oxide multilayer carbon nanotubes, demonstrating the porosity of the discrete oxide carbon nanotubes and the presence of many open ends.

[0090] A 3 wt% dispersion of oxidatively discrete carbon nanotubes was prepared by taking 20.45 g of an aqueous wet cake containing 4.4% solids of the above-mentioned oxidatively discrete carbon nanotubes into a 50 cc glass bottle and adding 9.55 g of a solution prepared by dissolving 0.45 g of 10,000 daltons of polyvinylpyrrolidone (PVP) in 9.15 g of water. The weight ratio of PVP to discrete carbon nanotubes was 0.5 to 1. The bottle and its contents were then ultrasonically treated for 3 hours using an ultrasonic treatment bath while maintaining the temperature below 40°C. This process was repeated as needed to prepare larger volumes for coating the powder. Polyvinylpyrrolidone with a molecular weight of 10,000 daltons was selected due to its compatibility with Vestasint. The Hansen solubility parameters for the dispersion, polarity, and hydrogen bonding components of PVP were 17.4, 8.8, and 14.9, respectively. For nylon 12, the Hansen solubility parameters for dispersion, polarity, and hydrogen bonding components are 18.5, 8.1, and 9.1, respectively.

[0091] Coating with Vestasint 3054D powder.

[0092] Appropriate weights of discrete carbon oxide nanotubes were added to the dispersion to create a coating thickness ranging from 0.05 to 2% by weight on a total of 60 g of coating powder. The discrete carbon nanotube to polymer ratio ranged from 0.05 to 2% by weight. Water was added to bring the total weight to 130 g, and the slurry was mixed using a Thinky mixer at 2000 rpm for 3 minutes. The slurry was then spread thinly on a glass tray and dried in a convection oven at 100°C for 4 hours.

[0093] Differential scanning calorimetry (DSC) was performed using a TA DSC Q20 instrument by first placing approximately 10 mg of coated pellets into a DSC pan, heating to 180°C at 10°C / min, then cooling to -100°C at 5°C / min, and subsequently reheating to 180°C at 10°C / min. The glass transition temperature, peak melting point, endothermic melting, peak recrystallization temperature, and exothermic recrystallization were recorded. The heat of fusion for 100% crystalline nylon 12 was assumed to be 246 J / g. ASTM E1356-08 (2014) is used as a standard test method for determining the glass transition temperature by differential scanning calorimetry.

[0094] Optical photographs of the powder before and after sintering were taken using a Nikon camera.

[0095] To determine the properties of the coating, secondary electron microscopy (SEM) was performed on the powder. The powder was pressed onto an adhesive carbon disk placed on an aluminum stub. An electron beam energy of 2KV or 5KV was selected at a working distance of approximately 9 mm.

[0096] The particle size of Vestasint 3054D ranged from approximately 30 to 150 micrometers, with a median of approximately 70 micrometers. The discrete carbon nanotube coating thickness was estimated based on spherical particles with an average diameter of 70 micrometers, the relative weight of the carbon nanotubes to the polymer, and the assumption of a packing density of 0.25 g / cc for the dried discrete multilayer carbon nanotube coating. The packing density of the carbon nanotubes coating the particles can be obtained from electron microscopy studies of microtome-sintered particles or by exfoliation of the coating from the particles.

[0097] [Table 1]

[0098] Figure 2 shows a 50,000x electron microscope image of a single layer of discrete oxidized multilayer carbon nanotube coating on Vestasint 3054D powder particles. Polyvinylpyrrolidone is observed on the tube surface as small spheres with a diameter of approximately 20-40 nanometers. The spherical nature of the PVP indicates that the PVP does not form a continuous coating, i.e., the porosity is maintained by the discrete carbon nanotubes. Figure 3 shows a discrete carbon nanotube coating with 0.1 wt% discrete carbon nanotubes.

[0099] The nylon 12 polymer itself has a glass transition temperature (Tg) of approximately 50°C and a melting peak at 175°C. Because the molecular weight of block nylon 12 in Vestasint is lower compared to homopolymer nylon 12, the melting point is expected to decrease, and the Tg may also decrease compared to homopolymer nylon 12.

[0100] Figures 4 and 5 show thermograms of the heating-cooling-heating cycle for uncoated Vestasint 3054D and coated Vestasint 3054D, respectively. The differential scanning calorimeter thermogram of the initial heating cycle shown in Figure 4 indicates that particle melting is complete when the particles begin to melt at approximately 140°C. Upon cooling, the peak temperature for crystallization of nylon 12 domains appears at 128°C for Vestasint without the discrete carbon nanotube coating and at approximately 125°C for Vestasint with a 2 wt% discrete carbon nanotube coating (Figure 5).

[0101] Another small thermal event occurs during cooling at approximately 50°C. Upon reheating, a small endothermic event, named Tm1 in Table 2, is present in the 35-41.5°C range. These two events during cooling and heating are due to the Tg of the nylon phase and / or the crystallization of small amounts of poly(tetramethylene oxide). The Tg during heating is shown as approximately -58°C, due to the almost amorphous PTMO phase, followed by the melting of the nylon 12 block with a peak melting temperature of approximately 152°C. The results for the specimens from the first cooling and second reheating are shown in Table 2.

[0102] [Table 2]

[0103] As can be seen from the values ​​of the heat of fusion ΔHm during melting and the heat of fusion ΔHc during recrystallization in Table 2, coating with oxidized discrete carbon nanotubes clearly increases the amount of crystallinity of nylon 12 domains.

[0104] Vestasint 3054D particles coated with discrete carbon oxide nanotubes in the range of 0.05–2 wt% of the particle size were observed to fuse well after heating to 180°C. The fused film was observed to decrease in surface gloss as the thickness of the initial discrete carbon nanotube coating increased. At an interparticle coating thickness of approximately 2 micrometers, the Vestasint polymer could still diffuse through the coating, allowing for the creation of a coherent film.

[0105] Example 2.

[0106] A process for coating Luvosint HTN particles with discrete oxide carbon nanotubes.

[0107] Luvosint HTN is a low-temperature pulverized, high-temperature semi-crystalline nylon copolymer prepared from hexamethylenediamine and isophthalic acid. The average particle size was determined to be 73 micrometers. The oxidized discrete multilayer carbon nanotubes used were the same as those in Example 1.

[0108] An aqueous dispersion of 3% by weight of oxidized discrete multilayer carbon nanotubes and 1.05% by weight of polyvinyl alcohol with an Mw of approximately 30,000 Daltons and a hydrolysis value of approximately 3% was prepared using an ultrasonic bath over 3 hours while maintaining the temperature below 40°C.

[0109] A series of coatings of 0.05, 0.1, 0.25, and 0.5 by weight of oxidized discrete carbon nanotubes were applied to the final dried material. 70 g of a concentrated solution was prepared by adding a weight appropriate for coating 60 g of powder to water, and then added to 60 g of Luvosint HTN. The slurry was mixed manually and then mixed in a Thinky mixer at 2000 rpm for 3 minutes. The resulting mixture was spread thinly on a glass tray and dried in a convection oven at 100°C for 4 hours, followed by drying under vacuum at 80°C for 2 hours. The powder was easily crushed in a glass bottle to obtain a fine powder.

[0110] The coating thickness of discrete carbon nanotubes was estimated by assuming spherical particles with an average diameter of 73 micrometers, a particle density of 1.14 g / cc, and a packing density of discrete carbon nanotubes of 0.25 g / cc.

[0111] [Table 3]

[0112] To observe the coating, secondary electron microscopy (SEM) was performed on the powder. The powder was pressed onto an adhesive carbon disk placed on an aluminum stub. SEM images can be difficult to obtain on non-conductive polymers due to electron charging. Electron charging can result in blurring or undulation. Higher loading of the coating made imaging at higher magnification easier. Typical conditions were a 1KV electron beam with a working distance of approximately 9 mm.

[0113] In a 0.25 wt% discrete oxidized multilayer carbon nanotube coating on powder, separation of the carbon nanotube coating from Luvosint HTN was observed in several small areas on the particle surface (electron microscope image Figure 6). However, some discrete carbon nanotubes remained adhered to the nylon surface from which the thick coating had been removed. This indicates that polyvinyl alcohol is suitable both as a polymer surfactant for the dispersion of discrete carbon nanotubes and for providing adhesion of discrete carbon nanotubes to nylon particles.

[0114] The electron microscope image in Figure 7 shows a coating of 0.5 wt% discrete oxide carbon nanotubes and polyvinyl alcohol on Luvosint HTN particles, after removing a portion of the coating and polishing the particles to determine the thickness of the coating layer. The coating thickness was determined to be 313 nm. The coating was also observed to be porous throughout its entire thickness.

[0115] DSC was performed by first placing approximately 10 mg of coated pellets into a DSC pan, heating to 300°C at 10°C / min, then cooling to 0°C at 10°C / min, and subsequently reheating to 300°C at 10°C / min. The glass transition temperature, peak melting point, endothermic melting, peak recrystallization temperature, and exothermic recrystallization temperature were recorded. The heat of fusion for 100% crystalline nylon was assumed to be 246 J / g. The midpoint of the glass transition temperature during reheating was 89.5°C.

[0116] [Table 4]

[0117] The DSC of the first heating cycle shows that particle sintering begins in the 200°C range for uncoated Luvosint HTN powder, with a slight increase in particle sintering temperature with increasing discrete carbon nanotube coating content, reaching approximately 205°C for powder coated with 0.5 wt%. Within the range of discrete carbon nanotubes used herein, the Tg and Tm peak values ​​are essentially the same regardless of coating. The increase in Tc value is considered to be a result of improved heat transport in the powder due to the discrete carbon nanotube coating. The heat of fusion values ​​suggest a crystallinity of 20–22% by weight.

[0118] After sintering the particles at 300°C, the discrete carbon nanotube coated powders at 0.05% and 0.1% by weight yielded a glossy surface, while the discrete carbon nanotube coated powders at 0.25% and 0.5% by weight were matte. In each case, the coated powders up to 0.5% by weight yielded a coherent film after cooling, meaning that aromatic nylon penetrated through the coating, resulting in good interparticle adhesion.

[0119] Two-electrode resistance measurements using a digital resistance meter (capable of measuring up to 25 megaohms) on powder sintered on an aluminum plate yielded values ​​of 6 megaohms for a 0.25 wt% discrete carbon oxide nanotube coating on Luvosint HTN particles and 0.6 megaohms for a 0.5 wt% discrete carbon oxide nanotube coating.

[0120] Example 3.

[0121] Coating of polyetherketone powder with carbon fiber fillers.

[0122] The polyether ketone has an estimated chopped carbon fiber content of 12% by weight. The average particle size is 70 micrometers. The oxidative-discrete multilayer carbon nanotubes used were the same as those used in Example 1.

[0123] An aqueous dispersion of 3 wt% oxidized discrete multilayer carbon nanotubes and 0.75 wt% polyvinylpyrrolidone with a molecular weight of approximately 40,000 daltons (Mw) was prepared using an ultrasonic bath over 3 hours while maintaining the temperature below 40°C.

[0124] A series of coatings of 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, and 0.4 wt% discrete oxidized carbon nanotubes were prepared for PEK carbon fiber powder. A concentrated solution of discrete oxidized carbon nanotubes, in a weight appropriate for coating 60 g of powder, was added to water to prepare 70 g of the solution, which was then added to 60 g of powder. The slurry was mixed manually and then in a Thinky mixer at 2000 rpm for 3 minutes. The resulting mixture was spread thinly on a glass tray and dried in a convection oven at 100°C for 4 hours, followed by drying under vacuum at 80°C for 2 hours. The powder was easily crushed in a glass bottle to obtain a fine powder.

[0125] Optical microscopy revealed that the coating uniformly covered the surface of the powder. Sintering the particles using a hot plate yielded a film with good mechanical integrity. When the coating load on the particles was 0.25% by weight or more, the surface electrical resistivity after sintering was 10 8 It is determined to be less than an ohm square, and therefore suitable for producing articles with electrostatic dissipation properties.

[0126] Example 4.

[0127] Coating of silicon anode material (MSE supplies).

[0128] 10 g of single-walled carbon nanotubes (Korbon) and 3 g of carboxymethylcellulose sodium CMC (Ashland) with a molecular weight of approximately 30,000 daltons were added to 990 g of deionized water. The mixture was passed through a high-shear mixer while maintaining the temperature below 35°C until a stable dispersion of discrete single-walled carbon nanotubes was obtained, as observed by optical microscopy at a magnification of 168x. A slurry of silicon anode material was prepared using 1 g of silicon anode and 1.1 g of the single-walled carbon nanotube CMC dispersion. This resulted in a weight ratio of silicon anode material to single-walled carbon nanotubes of 1:0.011. The slurry was dried at 110°C for 1 hour with stirring during the process.

[0129] Figure 7, an electron microscope image at 20,000x magnification, shows discrete single-walled carbon nanotubes coating silicon anode particles. Most of the single-walled carbon nanotubes were in the form of thin ropes. No aggregates of single-walled carbon nanotubes with diameters exceeding 5 micrometers were observed.

[0130] A pressed layer of anode particles coated with 1.1 wt% discrete single-walled carbon nanotubes yielded a surface resistance of approximately 70 ohms square, while uncoated anode particles yielded a resistance of approximately 3 kiloohms square.

[0131] Example 5.

[0132] Nickel-manganese-cobalt oxide material (BASF NMC 523) coating

[0133] The same single-walled carbon nanotube dispersion as in Example 4 was used. A slurry of NMC cathode material was prepared using 5.9 g of NMC material and 1.85 g of single-walled carbon nanotube CMC dispersion. This resulted in a weight ratio of NMC cathode material to single-walled carbon nanotubes of 1:0.0031. The slurry was dried at 110°C for 1 hour with stirring during the process.

[0134] Figure 8, an electron microscope image at 20,000x magnification, shows discrete single-walled carbon nanotubes coating NMC cathode electroactive material particles. Most of the single-walled carbon nanotubes were in the form of thin ropes. No aggregates of single-walled carbon nanotubes with diameters exceeding 5 micrometers were observed.

[0135] A pressed layer of NMC particles coated with 0.31 wt% discrete single-walled carbon nanotubes yielded a surface resistance of approximately 200 ohms square, while uncoated NMC cathode particles yielded a resistance exceeding 25 megaohms square.

[0136] Embodiment

[0137] 1. A composition for energy storage and additive manufacturing,

[0138] A composition comprising a coating containing discrete carbon nanotubes, wherein the coating has an average thickness of about 5 nanometers to about 2000 nanometers, the coating covers at least about 50% of the surface area of ​​the particles, and the particles have an average diameter of less than about 1000 micrometers.

[0139] 2. The composition according to Embodiment 1, wherein the particles having an average diameter of less than approximately 1000 micrometers are selected from the group consisting of organic polymers, non-metallic materials, and any mixture thereof.

[0140] 3. The composition according to Embodiment 2, wherein the organic polymer is an elastomer having a glass transition temperature of less than approximately 25°C.

[0141] 4. The composition according to Embodiment 2, wherein the organic polymer is a thermoplastic having a glass transition temperature greater than approximately 25°C.

[0142] 5. The composition according to Embodiment 2, wherein the element is selected from the group consisting of silicon, sulfur, carbon, ceramics, metals, metal oxides, metal salts, transition metal oxides, transition metal salts, silicon oxide, tin, graphite, hard carbon, gallium, germanium, electroactive ceramics, graphene, graphene oxide, lithium, titanium dioxide, and any mixture thereof.

[0143] 6. The composition according to Embodiment 5, wherein the unequipped element is an electroactive material.

[0144] 7. The composition according to Embodiment 1, wherein the coating has a porosity of about 0.05 to about 0.95.

[0145] 8. The composition according to Embodiment 1, wherein the carbon nanotubes are selected from the group consisting of single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, and any mixture thereof.

[0146] 9. The composition according to Embodiment 1, further comprising a carbonaceous material selected from the group consisting of carbon black, carbon fiber, graphite, graphene, reduced graphene, carbon nanorods, randomly stratified graphene, graphene oxide, and any mixture thereof.

[0147] 10. The composition according to Embodiment 8, wherein the aspect ratio pattern of the discrete carbon nanotubes is unimodal.

[0148] 11. The composition according to Embodiment 8, wherein the aspect ratio pattern of the discrete carbon nanotubes is at least bimodal.

[0149] 12. The composition according to Embodiment 8, wherein the majority of the carbon nanotubes have a length greater than about 0.2 micrometers.

[0150] 13. The composition according to Embodiment 1, wherein the coating further comprises carbon nanotubes in the form of entangled bundles or ropes, the bundles or ropes of carbon nanotubes having at least one dimension of less than about 10 micrometers, and the bundles or ropes constitute less than about 20% of the total mass of the coating.

[0151] 14. The composition according to Embodiment 9, wherein the weight ratio of discrete carbon nanotubes to carbonaceous material is about 1:99 to about 99:1.

[0152] 15. The composition according to Embodiment 1, wherein at least a portion of the discrete carbon nanotubes comprises surface-modified discrete carbon nanotubes.

[0153] 16. The composition according to Embodiment 15, wherein at least a portion of surface-modified discrete carbon nanotubes are attached to particles having an average diameter of less than about 1000 micrometers by covalent bonds, ionic bonds, hydrogen bonds, or any mixture thereof.

[0154] 17. The composition according to Embodiment 15, wherein the surface-modified discrete carbon nanotubes include surface modifications selected from the group consisting of molecules containing oxygen, silicon, titanium, zirconium, sulfur, phosphorus, nitrogen, or any mixture thereof.

[0155] 18. The composition according to embodiment 15, wherein the surface-modified discrete carbon nanotubes comprise surface modification with a compound selected from the group consisting of anionic, cationic, nonionic and zwitterionic surfactants, polyvinyl alcohol, a copolymer of polyvinyl alcohol and polyvinyl acetate, polyvinyl pyrrolidone and its copolymers, carboxymethyl cellulose, carboxypropyl cellulose, carboxymethylpropyl cellulose, hydroxyethyl cellulose, polyetherimine, polyethers, starch, and any mixture thereof.

[0156] 19. The composition according to embodiment 18, wherein the surface modification of the discrete carbon nanotubes has a value of the dispersion parameter of the Hansen solubility parameter within about 2 J from the value of the dispersion parameter of the Hansen solubility parameter of particles having an average diameter of less than about 1000 micrometers. 0.5 m -1.5

[0157] 20. The composition according to embodiment 15, further comprising an electrolyte, wherein the surface modification of the discrete carbon nanotubes has a value of the dispersion parameter of the Hansen solubility parameter within about 2 J from the value of the dispersion parameter of the Hansen solubility parameter of the electrolyte. 0.5 m -1.5

[0158] 21. The composition according to embodiment 18, wherein the surface modification is miscible with particles having an average diameter of less than about 1000 micrometers.

[0159] 22. The composition according to embodiment 15, wherein the surface-modified discrete carbon nanotubes and the particles having an average diameter of less than about 1000 micrometers are selected to promote a chemical interaction between the surface-modified discrete carbon nanotubes and the particles having an average diameter of less than about 1000 micrometers.

[0160] 23. The composition according to embodiment 22, wherein the surface-modified discrete carbon nanotubes and the particles having an average diameter of less than about 1000 micrometers are chemically bonded.

[0161] 24. The composition according to Embodiment 18, wherein the surface modification is miscible with the electrolyte.

[0162] 25. An article comprising the composition described in Embodiment 1.

[0163] 26. The article according to Embodiment 25, wherein the composition is bonded or sintered.

[0164] 27. The composition according to Embodiment 15, wherein the volume fraction of the surface modification is less than about 0.8 of the total volume of the discrete carbon nanotubes and the surface modification.

[0165] 28. The article according to Embodiment 26, having a surface resistance of less than approximately 10 billion ohms square.

[0166] 29. The composition according to Embodiment 1, further comprising an electrolyte selected from the group consisting of gels, solids, or any mixture thereof, wherein the particles have an average diameter of less than approximately 1000 micrometers.

[0167] 30. The composition according to Embodiment 1, wherein at least a portion of the particles having an average diameter of less than approximately 1000 micrometers are of a size of less than 1 micrometer in at least one dimension.

[0168] 31. The composition according to Embodiment 1, further comprising uncoated particles, wherein the ratio of coated particles to uncoated particles is in the range of 10:90 to 99:1 based on the total weight of the particles.

[0169] 32. The composition according to Embodiment 1, wherein the coated particles are assembled using a dry or liquid electrode process to produce electrodes for an energy storage or collection device.

[0170] 33. The composition according to Embodiment 1, which has been sintered or bonded by a laser.

[0171] 34. The composition according to Embodiment 1, comprising at least one magnetic metal and / or alloy.

[0172] 35. The composition according to Embodiment 34, wherein the magnetic metal and / or alloy thereof is selected from the group consisting of iron, chromium, aluminum, uranium, platinum, copper, cobalt, lithium, nickel, neodymium, oxygen, palladium, manganese, tin, molybdenum, and samarium elements, and mixtures thereof.

Claims

1. A composition for energy storage and additive manufacturing, A composition comprising a coating containing discrete carbon nanotubes, wherein the coating has an average thickness of about 5 nanometers to about 2000 nanometers, the coating covers at least about 50% of the surface area of ​​the particles, and the particles have an average diameter of less than about 1000 micrometers.

2. The composition according to claim 1, wherein the particles having an average diameter of less than approximately 1,000 micrometers are selected from the group consisting of organic polymers, non-metallic materials, and any mixture thereof.

3. The composition according to claim 2, wherein the organic polymer is an elastomer having a glass transition temperature of less than about 25°C.

4. The composition according to claim 2, wherein the organic polymer is a thermoplastic having a glass transition temperature of about 25°C.

5. The composition according to claim 2, wherein the aforementioned non-metallic element is selected from the group consisting of silicon, sulfur, carbon, ceramics, metals, metal oxides, metal salts, transition metal oxides, transition metal salts, silicon oxide, tin, graphite, hard carbon, gallium, germanium, ceramics, graphene, graphene oxide, lithium, titanium dioxide, calcium carbonate, talc, magnesium carbonate, wollastonite, glass beads, glass fibers, glass flakes, fly ash, dolomite, barium sulfate, aluminum hydroxide, halloysite, mica, hematite, and any mixtures thereof.

6. The composition according to claim 5, wherein the aforementioned non-functional element is an electroactive material.

7. The composition according to claim 1, wherein the coating has a porosity of about 0.05 to about 0.

95.

8. The composition according to claim 1, wherein the carbon nanotube is selected from the group consisting of single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, and any mixture thereof.

9. The composition according to claim 1, further comprising a carbonaceous material selected from the group consisting of carbon black, carbon fiber, graphite, graphene, reduced graphene, carbon nanorods, randomly stratified graphene, graphene oxide, and any mixture thereof.

10. The composition according to claim 8, wherein the aspect ratio of the discrete carbon nanotubes is unimodal.

11. The composition according to claim 8, wherein the aspect ratio pattern of the discrete carbon nanotubes is at least bimodal.

12. The composition according to claim 8, wherein the majority of the carbon nanotubes have a length greater than about 0.2 micrometers.

13. The composition according to claim 1, wherein the coating further comprises carbon nanotubes in the form of entangled bundles or ropes, the bundles or ropes of carbon nanotubes having at least one dimension of less than about 10 micrometers, and the bundles or ropes constitute less than about 20% of the total mass of the coating.

14. The composition according to claim 9, wherein the weight ratio of discrete carbon nanotubes to carbonaceous material is about 1:99 to about 99:

1.

15. The composition according to claim 1, wherein at least a portion of the discrete carbon nanotubes comprises surface-modified discrete carbon nanotubes.

16. The composition according to claim 15, wherein at least a portion of the surface-modified discrete carbon nanotubes are attached to the particles having an average diameter of less than about 1,000 micrometers by covalent bonds, ionic bonds, hydrogen bonds, or any combination thereof.

17. The composition according to claim 15, wherein the surface-modified discrete carbon nanotubes include a surface modification selected from the group consisting of molecules containing oxygen, silicon, titanium, zirconium, sulfur, phosphorus, nitrogen, or any mixture thereof.

18. The composition according to claim 15, wherein the surface-modified discrete carbon nanotubes are surface-modified with compounds selected from the group consisting of anionic, cationic, nonionic, and zwitterionic surfactants, polyvinyl alcohol, copolymers of polyvinyl alcohol and polyvinyl acetate, polyvinylpyrrolidone and its copolymers, carboxymethylcellulose, carboxypropylcellulose, carboxymethylpropylcellulose, hydroxyethylcellulose, polyetherimines, polyethers, starch, and any mixtures thereof.

19. The surface modification of the discrete carbon nanotubes results in a value of approximately 2 J from the dispersion parameter of the Hansen solubility parameter of particles having an average diameter of less than approximately 1000 micrometers. ０．５ I understand －１．５ The composition according to claim 18, having a value of the dispersion parameter of the Hansen solubility parameter within the range of the Hansen solubility parameter.

20. The electrolyte further contains the surface modification of the discrete carbon nanotubes, which is approximately 2 J from the value of the dispersion parameter of the Hansen solubility parameter of the electrolyte. ０．５ I understand －１．５ The composition according to claim 15, having a value of the dispersion parameter of the Hansen solubility parameter within the range of the Hansen solubility parameter.

21. The composition according to claim 16, wherein the surface-modified discrete carbon nanotubes and the particles having an average diameter of less than about 1,000 micrometers are chemically bonded together.

22. The composition according to claim 18, wherein the surface-modifying compound is miscible with an electrolyte.

23. The composition according to claim 15, wherein the volume fraction of the surface modification is less than about 0.8 of the total volume of the discrete carbon nanotubes and the surface modification.

24. The composition according to claim 1, wherein the particles having an average diameter of less than approximately 1,000 micrometers further comprise an electrolyte selected from the group consisting of gels, solids, and any mixtures thereof.

25. The composition according to claim 1, comprising at least one magnetic metal and / or alloy, wherein the magnetic metal and / or alloy thereof is selected from the group consisting of iron, chromium, aluminum, uranium, platinum, copper, cobalt, lithium, nickel, neodymium, oxygen, palladium, manganese, tin, molybdenum, and samarium elements, and mixtures thereof.

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