Supercapacitor electrode coating material comprising active composite particles and conductive carbonaceous particles

Abstract

Disclosed herein is a coating for use as a supercapacitor electrode. The coating comprises active composite particles and conductive carbon-containing particles, the active composite particles comprising activated metal oxide particles and carbon-containing support particles.

Description

[0001] Government Contracts

[0002] This disclosure was made with government support under Government Contract No. 2021039-142041 awarded by the U.S. Army Ground Vehicle Systems Center. The U.S. Government has certain rights in this disclosure.

[0003] CROSS-REFERENCE TO RELATED APPLICATIONS

[0004] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 378,886, filed on October 10, 2022, which is incorporated herein by reference. Technical Field

[0005] Disclosed are coatings for supercapacitor electrodes comprising active composite particles and conductive carbonaceous particles. Background Art

[0006] There is a large demand for high-power energy resources for various products, such as portable electronic devices and electric vehicles. Supercapacitors provide a promising alternative to conventional capacitors and can replace or be combined with batteries for such uses. The specific energy of supercapacitors can be several orders of magnitude higher than that of conventional capacitors. In addition, supercapacitors are able to store energy and deliver power at relatively high rates that exceed what batteries can achieve. Summary of the invention

[0007] Disclosed herein is a coating for use as a supercapacitor electrode, wherein the coating comprises active composite particles and conductive carbonaceous particles, wherein the active composite particles comprise activated metal oxide particles and carbonaceous support particles.

[0008] Disclosed herein are active composite particles for use in supercapacitor electrode coatings. The active composite particles comprise activated metal oxide particles and carbonaceous support particles.

[0009] A method for preparing active composite particles for supercapacitor electrode coating is disclosed herein, which comprises spray drying an aqueous solution containing activated metal oxide particles and carbonaceous support particles, and recovering active composite particles containing activated metal oxide particles and carbonaceous support particles.

[0010] Disclosed herein is a supercapacitor electrode comprising a current collector substrate and an electrode coating, wherein the electrode coating comprises active composite particles and conductive carbonaceous particles, wherein the active composite particles comprise activated metal oxide particles and carbonaceous support particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Included are rheological curves of various aqueous graphene dispersions.

[0012] Figure 2 Included are viscosity measurements of aqueous dispersions containing various amounts of graphene.

[0013] Figure 3 Includes instability indices for various aqueous graphene dispersions.

[0014] Figure 4 Included are rheological data for dispersions containing MnO2, graphene, conductive carbon, and a binder.

[0015] Figure 5 is a cross-sectional scanning electron microscope image of the MnO2+GNP cathode coating on carbon-coated Ni foil.

[0016] Figure 6 is a cross-sectional scanning electron microscope electron dispersive spectroscopy (SEM-EDS) image of the MnO2+GNP cathode coating on carbon-coated Ni foil.

[0017] Figure 7 is a cross-sectional scanning electron microscope image of the MnO2|GNP cathode coating on carbon-coated Ni foil.

[0018] Figure 8 is a cross-sectional scanning electron microscope electron dispersive spectroscopy (SEM-EDS) image of the MnO2|GNP cathode coating on carbon-coated Ni foil.

[0019] Fig. 9 is a cross-sectional scanning electron microscope image of the spray-dried MnO2|GNP cathode coating on carbon-coated Ni foil.

[0020] Fig.10 is a cross-sectional scanning electron microscopy electron dispersive spectroscopy (SEM-EDS) image of a spray-dried MnO2|GNP cathode coating on carbon-coated Ni foil.

[0021] Fig.11 Included is a plot of capacitance versus current density (j) for an electrode having an 80 / 10 / 10 active / carbon black / binder coating.

[0022] Fig.12 Included is a plot of capacitance versus current density (j) for an electrode having an 88 / 2 / 10 active / carbon black / binder coating.

[0023] Fig.13 Included is a plot of capacitance versus current density (j) for an electrode having an 80 / 10 / 10 active / carbon black / binder coating.

[0024] Fig.14Included is a plot of capacitance versus current density (j) for an electrode having an 80 / 10 / 10 active / carbon black / binder coating.

[0025] Fig.15 Cyclic voltammetry of full cells using an 80 / 10 / 10 active / carbon black / binder electrode composition was included.

[0026] Fig.16 Included is a plot of capacitance versus current density (j) for an electrode having an 80 / 10 / 10 active / carbon black / binder coating.

[0027] Fig.17 Includes composite and interfacial resistivity measurements of supercapacitor cathode coatings on foil having an 88 / 2 / 10 active / carbon black / binder formulation. DETAILED DESCRIPTION

[0028] The supercapacitor electrode coating comprises active composite particles and conductive carbonaceous particles. The supercapacitor electrode coating may also include a binder. The active composite particles may include activated metal oxide particles and graphene carbon nanoparticles. As used herein, when referring to metal oxide particles, the term "activated" means that the material undergoes physical, thermal and / or chemical processes during use to store ionic charge and / or electrochemically interact or react with other components.

[0029] Electrode coatings can be used in various types of supercapacitors, including asymmetric supercapacitors, symmetric supercapacitors, lithium ion capacitors, sodium ion capacitors, etc. For example, as known to those skilled in the art, an asymmetric supercapacitor or an asymmetric pseudocapacitor includes two electrodes of different materials, namely a cathode and an anode, which are separated by an ion-conducting, electrically insulating electrolyte and a separator contained in the cell. The electrodes of different composition store electrical energy by adsorbing ions with opposite charges onto their respective surfaces.

[0030] The electrode coating can be used to produce a supercapacitor cathode and / or a supercapacitor anode. Although supercapacitor cathodes are primarily described herein, it should be understood that the supercapacitor coatings of the present invention can also be used as supercapacitor anodes.

[0031] Based on the total weight of the coating, the supercapacitor electrode coating can generally contain at least 50 weight percent, or at least 60 weight percent, or at least 70 weight percent of active composite particles. The supercapacitor electrode coating can generally contain up to 99 weight percent, or up to 98 weight percent, or up to 95 weight percent of active composite particles. The supercapacitor electrode coating can generally contain 50 to 99 weight percent, such as 60 to 98 weight percent or 70 to 95 weight percent of active composite particles.

[0032] Based on the total weight of the coating, the supercapacitor electrode coating can generally include at least 0.5 weight percent, or at least 1 weight percent, or at least 2 weight percent, or at least 4 weight percent, or at least 5 weight percent, or at least 8 weight percent of conductive carbonaceous particles. The supercapacitor electrode coating can generally include up to 50 weight percent, or up to 30 weight percent, or up to 20 weight percent, or up to 15 weight percent, or up to 12 weight percent of conductive carbonaceous particles. The supercapacitor electrode coating can generally include 0.5 to 50 weight percent, such as 1 to 30 weight percent, or 2 to 20 weight percent, or 5 to 15 weight percent, or 8 to 12 weight percent of conductive carbonaceous particles. The conductive carbonaceous particles can include carbon black, graphite.

[0033] The supercapacitor electrode coating may typically include a binder, for example, at least 0.01 weight percent, or at least 0.1 weight percent, or at least 1 weight percent, or at least 2 weight percent of the binder, based on the total weight of the coating. The supercapacitor electrode coating may typically include up to 20 weight percent, or up to 15 weight percent, or up to 10 weight percent of the binder. The supercapacitor electrode coating may typically include 0 to 20 weight percent, for example, 1 to 15 weight percent or 2 to 10 weight percent of the binder.

[0034] The active composite particles can generally contain at least 1 weight percent, such as at least 50 weight percent or at least 70 weight percent of activated metal oxide particles. The active composite particles can contain up to 99 weight percent, such as up to 95 weight percent or up to 90 weight percent of activated metal oxide particles.

[0035] The active composite particles can generally contain at least 1 weight percent, such as at least 5 weight percent or at least 10 weight percent of carbonaceous support particles. The active composite particles can contain up to 99 weight percent, such as up to 50 weight percent or up to 30 weight percent of carbonaceous support particles.

[0036] The active composite particles can generally contain 1 to 99 weight percent of activated metal oxide particles and 1 to 99 weight percent of carbonaceous support particles, for example, 50 to 95 weight percent of activated metal oxide particles and 5 to 50 weight percent of carbonaceous support particles, or 70 to 90 weight percent of activated metal oxide and 10 to 30 weight percent of carbonaceous support particles.

[0037] Active composite particles can include composite binders, which can help to bond activated metal oxide particles and graphene carbon nanoparticles together, and / or help to bond particles comprising growth or the activated metal particles deposited on the graphene carbon nanoparticles together. Suitable composite binders include polyacrylic acid, polyvinyl pyrrolidone, poly-(maleic acid), poly-(4-styrene sulfonic acid) sodium salt, poly-(4-styrene sulfonic acid-co-maleic acid) sodium salt etc. Composite binders can also be cross-linked with carbodiimide crosslinking agents such as Carbodilite V-02-L2 or melamine. Composite binders can account for zero to 10 weight percents or 0.01 to 5 weight percents or 0.1 to 2 weight percents of active composite particles.

[0038] There may be 0 to 5 or 10 weight percent of a dispersant in the active composite particles and / or in a powder comprising the active composite particles. For example, suitable dispersants in or mixed with the active composite particles may include polyacrylic acid, polyvinyl pyrrolidone, poly(maleic acid), poly(4-styrene sulfonic acid) sodium salt, poly(4-styrene sulfonic acid-co-maleic acid) sodium salt, and the like. For example, the dispersant may be an acrylic polymer containing acrylic acid neutralized with sodium hydroxide or potassium hydroxide. The dispersant may also be crosslinked with a carbodiimide crosslinking agent such as Carbodilite V-02-L2.

[0039] The active composite particles can have an average particle size of 100 nanometers to 100 microns, or 1 to 20 microns, or 2 to 10 microns, as measured by standard scanning electron microscope (SEM) tests. The composite particles can be dispersed on a fragment of a carbon tape attached to an aluminum sample stage and coated with Au / Pd for 20 seconds. The sample can then be analyzed in a Quanta250FEG SEM under high vacuum. The accelerating voltage can be set to 20.00 kV, and the spot size can be 3.0. Thirty particles can be measured from three different areas to provide the average particle size of each sample.

[0040] The activated metal oxide particles may include manganese oxide, potassium manganese oxide, sodium manganese oxide, lithium manganese oxide, nickel manganese oxide, iron manganese oxide, ruthenium oxide, cobalt oxide, manganese cobalt oxide, iron oxide, nickel oxide, nickel hydroxide, titanium oxide, iron cobalt oxide, vanadium oxide, etc. When the activated metal oxide is manganese oxide, it may be provided as stoichiometric MnO2, or as substoichiometric or superstoichiometric manganese oxide. Manganese oxide may be activated by including alkaline cations and water within the structure so that the chemical structure may be described as A x MnO ynH2O, where "A" is an alkali metal such as lithium, sodium or potassium, "x" is the number of alkali metals in the reduced chemical formula, "y" is the number of oxygens contained in the metal oxide structure, wherein y is generally less than or equal to 2, and "n" is the number of water molecules in the reduced chemical structure of the activated metal oxide. Manganese oxides can be further activated by reducing the oxidation state from 7+ to 4+, 3+, 2+ or neutral by electrochemical reduction with the aid of applied voltage or by chemical reducing agents such as ethanol, isopropanol, ethylene glycol, benzyl alcohol, 2-pyridinemethanol, furfuryl alcohol, poly(ethylene glycol), sodium thiosulfate, manganese(II) acetate, manganese(II) chloride, manganese(II) sulfate, etc. The other metal oxides mentioned above can be activated in a similar manner.

[0041] The carbonaceous carrier particles of the active composite particles can provide a conductive carrier structure on which the activated metal oxide particles can grow or deposit. As used herein, when referring to activated metal oxide particles and carbonaceous carrier particles, the term "growing on" means that the activated metal oxide particles are deposited on preformed carbonaceous carrier particles, including being directly deposited on the surface of such carbonaceous carrier particles, being deposited on other activated metal oxide particles previously deposited on carbonaceous carrier particles, growing in solution in the presence of carbonaceous carrier particles, and combinations thereof. Therefore, physical and / or chemical interactions may occur between the activated metal oxide particles and the carbonaceous carrier particles. For example, the activated metal oxide particles can grow or deposit on the carbonaceous carrier particles before or during a spray drying process, in which an aqueous solution or slurry containing particles is spray dried, as described more fully below. The carbonaceous carrier particles can include graphene carbon nanoparticles, such as thermally generated graphene carbon nanoparticles, exfoliated graphite graphene nanoparticles, carbon nanotubes, reduced graphene oxides, graphene oxides, fullerenes, etc.

[0042] The carbonaceous support particles may include activated carbon, which may be used in place of or in addition to the graphene carbon nanoparticles. The activated carbon support particles may be activated by thermal heat treatment, exposure to reactive metal oxide precursor materials such as potassium permanganate, manganese acetate, nickel acetate, nickel acetylacetonate, iron acetate, iron acetylacetonate, cobalt acetate, cobalt acetylacetonate, titanium chloride, titanyl sulfate, vanadium chloride, vanadium oxychloride, vanadium acetylacetonate, ruthenium chloride, (1,5-cyclooctadiene) ruthenium chloride, ruthenium acetylacetonate, etc. The activated carbon support particles may also be activated by using alkaline hydroxide salts such as lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, etc.

[0043] When the carbon-containing support particles include graphene carbon nanoparticles, such nanoparticles can include exfoliated graphite graphene, which can be obtained from commercial sources, such as Angstron, XG Sciences, and other commercial sources.

[0044] The hot graphene carbon nanoparticles can be thermally generated according to the methods and apparatus described in U.S. Patent Nos. 8,486,363, 8,486,364 and 9,221,688, which are incorporated herein by reference. Such thermally generated graphene carbon nanoparticles can be commercially available from Raymor. Other carbonaceous materials such as activated carbon can be used in combination with graphene carbon nanoparticles, or in place of graphene carbon nanoparticles.

[0045] As used herein, the term "graphene carbon particles" refers to particles having one or more layers of sp 2 Carbon particles of the structure of single-atom-thick planar sheets of bonded carbon atoms, carbon atoms densely packed in a honeycomb lattice. The average number of stacked layers can be less than 100, for example less than 50. The average number of stacked layers can be 30 or less, such as 20 or less, 10 or less, or in some cases 5 or less. The average number of stacked layers can be greater than 2, for example greater than 3 or greater than 4. At least a portion of the graphene carbon particles can be in the form of substantially curved, curled, wrinkled or buckled flakes. Graphene carbon nanoparticles can be turbostatic, that is, adjacent stacked atomic layers do not show the ordered AB Bernal stacking associated with conventionally exfoliated graphene, but show disordered or non-ABABAB stacking. Alternatively, graphene carbon particles can be in the form of nanotubes. Particles do not generally have a spherical or equiaxed morphology.

[0046] Graphene carbon nanoparticles can have a thickness of no more than 10 nanometers, no more than 5 nanometers or no more than 4 or 3 or 2 or 1 nanometers measured in a direction perpendicular to the carbon atom layer, such as no more than 3.6 nanometers. Graphene carbon particles can be from 1 atomic layer to 3, 6, 9, 12, 20 or 30 atomic layers thick or thicker at the most. The graphene carbon particles present in the composition can have at least 50 nanometers measured in a direction parallel to the carbon atom layer, such as greater than 100 nanometers, greater than 100 nanometers at the most 500 nanometers, or greater than 100 nanometers at the most 200 nanometers width and length in some cases. Graphene carbon particles can be provided in the form of ultrathin flakes, flakes or sheets with relatively high aspect ratio (aspect ratio is defined as the ratio of the longest dimension of particle to the shortest dimension of particle), and the ratio is greater than 3:1, such as greater than 10:1. Alternatively, when the graphene carbon particles are in the form of nanotubes, they can have an outer diameter ranging from 0.3 to 100 nanometers or 0.4 to 40 nanometers, a length ranging from 0.3 nanometers to 50 centimeters or 500 nanometers to 500 microns, and a length:diameter aspect ratio ranging from 1:1 to 100,000,000:1 or 10:1 to 10,000:1.

[0047] The graphene carbon particles can have a relatively low oxygen content. For example, even when having a thickness of no more than 5 nanometers or no more than 2 nanometers, the graphene carbon particles can also have an oxygen content of no more than 2 atomic weight percent, such as no more than 1.5 or 1 atomic weight percent, or no more than 0.6 atomic weight percent, such as about 0.5 atomic weight percent. The oxygen content of the graphene carbon particles can be measured using X-ray photoelectron spectroscopy, such as described in: DR Dreyer et al., Chem. Soc. Rev. 39, 228-240 (2010).

[0048] The graphene carbon particles may have a BET specific surface area of ​​at least 50 m2 / g, such as 70 to 1000 m2 / g, or in some cases 200 to 1000 m2 / g or 200 to 400 m2 / g. As used herein, the term "BET surface area" refers to a specific surface area determined by nitrogen adsorption according to the Bruno-Emmett-Taylor method described in the journal "The Journal of the American Chemical Society", 60, 309 (1938) according to ASTMD 3663-78 standard.

[0049] The graphene carbon particles may have a Raman spectrum 2D / G peak ratio of at least 0.9:1, or 0.95:1, or 1:1, such as at least 1.2:1 or 1.3:1. As used herein, the term "2D / G peak ratio" refers to the peak at 2692 cm -1 The intensity of the 2D peak at 1,580 cm -1 This 2D / G peak ratio may exist in graphene carbon nanoparticles having an average stacking layer number greater than 2, such as 3 or more stacking layers.

[0050] The graphene carbon particles may have a relatively low bulk density. For example, the graphene carbon particles may be characterized by having a bulk density of less than 0.2 g / cm 3 , such as not more than 0.1 g / cm 3 The bulk density (tapped density) of the ground graphene carbon particles can be determined by placing 0.4 grams of graphene carbon particles in a glass measuring cylinder with a readable scale. The cylinder is raised about one inch and tapped 100 times by hitting the bottom of the cylinder against a hard surface to allow the graphene carbon particles to settle inside the cylinder. The volume of the particles is then measured and the bulk density is calculated by dividing 0.4 grams by the measured volume, where the bulk density is expressed in g / cm 3 express.

[0051] The compression density and densification percentage of the graphene carbon particles may be less than the compression density and densification percentage of graphite powder and certain types of substantially flat graphene carbon particles. Compared with graphene carbon particles exhibiting higher compression density and higher density percentage, it is currently believed that lower compression density and lower density percentage each contribute to better dispersion and / or rheological properties. The compression density of the graphene carbon particles may be 0.9 or less, such as less than 0.8, less than 0.7, such as 0.6 to 0.7. The densification percentage of the graphene carbon particles may be less than 40%, such as less than 30%, such as 25% to 30%.

[0052] The compression density of the graphene carbon particles can be calculated from the measured thickness of a given mass of particles after compression. Specifically, the measured thickness is determined by subjecting 0.1 grams of graphene carbon particles to a cold press at a force of 15,000 pounds for 45 minutes in a 1.3 cm mold, with a contact pressure of 500 MPa. The compression density of the graphene carbon particles is then calculated from this measured thickness according to the following equation:

[0053]

[0054] The densification percentage of the graphene carbon particles was then determined as the calculated compressed density of the graphene carbon particles as determined above divided by 2.2 g / cm 3 (which is the density of graphite).

[0055] The graphene carbon particles can have a measured bulk liquid conductivity of at least 100 microSiemens, such as at least 120 microSiemens, such as at least 140 microSiemens, immediately after mixing and at a later time point, such as at 10 minutes or 20 minutes or 30 minutes or 40 minutes. The bulk liquid conductivity of the graphene carbon particles can be determined as follows. First, a sample of a solution including 0.5% graphene carbon particles in butyl cellosolve is sonicated for 30 minutes with a bath sonicator. Immediately after sonication, the sample is placed in a standard calibrated electrolytic conductivity cell (K=1). A Fisher Scientific AB 30 conductivity meter is introduced into the sample to measure the conductivity of the sample. The conductivity is plotted over the course of about 40 minutes.

[0056] The graphene carbon particles can be substantially free of unwanted or harmful materials. For example, the graphene carbon particles can contain zero or only trace amounts of polycyclic aromatic hydrocarbons (PAHs), for example, less than 2 weight percent PAH, less than 1 weight percent PAH, or zero PAH.

[0057] The starting graphene carbon nanoparticles can be prepared, for example, by heat treatment. The heat-generated graphene carbon particles can be made of a carbon-containing precursor material, which is heated to a high temperature in a hot zone such as a plasma. A carbon-containing precursor (such as a hydrocarbon provided in a gas or liquid form) is heated in a hot zone to produce graphene carbon particles in the hot zone or downstream thereof. For example, the heat-generated graphene carbon particles can be prepared by the system and method disclosed in U.S. Patent Nos. 8,486,363, 8,486,364 and 9,221,688.

[0058] Graphene carbon particles may be prepared by using the apparatus and method described in U.S. Pat. No. 8,486,363, wherein (i) one or more hydrocarbon precursor materials capable of forming dicarbon fragment species (such as n-propanol, ethane, ethylene, acetylene, vinyl chloride, 1,2-dichloroethane, allyl alcohol, propionaldehyde, and / or vinyl bromide) are introduced into a hot zone (such as a plasma); and (ii) the hydrocarbon is heated in the hot zone to a temperature of at least 1,000° C. to form graphene carbon particles. Graphene carbon particles may be prepared by using the apparatus and method described in U.S. Pat. No. 8,486,364, wherein (i) a methane precursor material (such as a material containing at least 50 percent methane or, in some cases, gaseous or liquid methane having a purity of at least 95 percent or 99 percent or more) is introduced into a hot zone (such as a plasma); and (ii) the methane precursor is heated in the hot zone to form graphene carbon particles. Such methods may produce graphene carbon particles having at least some, and in some cases all, of the characteristics described above.

[0059] During the production of graphene carbon particles by the above-mentioned thermal production method, a carbon-containing precursor is provided as a feed material that can be contacted with an inert carrier gas. The carbon-containing precursor material can be heated in a hot zone, for example, by a plasma system such as a DC plasma, an RF plasma, a microwave plasma, etc. The precursor material can be heated to a temperature ranging from greater than 2,000°C to 20,000°C or higher, such as 3,000°C to 15,000°C. For example, the temperature of the hot zone can be in the range of 3,500 to 12,000°C, such as 4,000 to 10,000°C. Although the hot zone can be generated by a plasma system, it should be understood that any other suitable heating system can be used to generate the hot zone, such as various types of furnaces, including electrically heated tubular furnaces, etc.

[0060] The gaseous stream may be contacted with one or more quench streams injected into the plasma chamber through at least one quench stream injection port. The quench stream may cool the gaseous stream to promote the formation of graphene carbon particles or control the particle size or morphology of the graphene carbon particles. After the gaseous product stream is contacted with the quench stream, ultrafine particles may be passed through a converging member. After the graphene carbon particles leave the plasma system, they may be collected. Any suitable device may be used to separate the graphene carbon particles from the gas stream, such as, for example, a bag filter, a cyclone separator, or deposition on a substrate.

[0061] Without being bound by any theory, it is currently believed that the aforementioned method for manufacturing graphene carbon nanoparticles is particularly suitable for producing graphene carbon nanoparticles with relatively low thickness and relatively high aspect ratio and relatively low oxygen content, as described above. In addition, contrary to the particles mainly produced with substantially two-dimensional (or flat) morphology, it is currently believed that such methods produce a large number of graphene carbon nanoparticles with substantially bending, curling, wrinkling or buckling morphology (referred to as "3D" morphology in this article). This characteristic is considered to be reflected in the previously described compression density characteristics, and is considered to be beneficial, because it is currently believed that when most of the graphene carbon particles have 3D morphology, "edge to edge" and "edge to face" contact between the graphene carbon particles in the composition can be promoted. This is considered to be because the particles with 3D morphology are less likely to assemble (due to lower van der Waals forces) in the composition compared with the particles with two-dimensional morphology. Furthermore, it is currently believed that even in the case of "face-to-face" contact between particles having 3D morphology, since a particle may have more than one face plane, the entire particle surface does not participate in a single "face-to-face" interaction with another single particle, but may participate in interactions with other particles, including other "face-to-face" interactions in other planes. Therefore, graphene carbon particles having 3D morphology may provide good electrical and / or thermal conductive paths in active composite particles and may be useful for obtaining electrical and / or thermal conductive properties in coatings.

[0062] Binders that can be used for supercapacitor electrode coatings include polymers such as poly(vinyl esters), poly(vinyl alcohols), poly(vinyl acetals), poly(vinyl ethers), poly(N-vinyl amides), poly(N-vinyl lactams), poly(N-vinyl amines), and copolymers thereof. Examples of poly(vinyl esters) include poly(vinyl acetate), poly(vinyl benzoate), poly(vinyl propionate), poly(vinyl pivalate), poly(vinyl 2-ethylhexanoate), poly(vinyl neodecanoate), and poly(vinyl neononanoate), and copolymers thereof. Examples of poly(vinyl ethers) include poly(methyl vinyl ether), poly(ethyl vinyl ether), poly(butyl vinyl ether), poly(isobutyl vinyl ether), poly(cyclohexyl vinyl ether), poly(phenyl vinyl ether), and poly(benzyl vinyl ether), and copolymers thereof. Examples of poly(N-vinylamides) and poly(N-vinyllactams) include poly(N-vinylformamide), poly(N-vinylacetamide), poly(N-vinyl-N-methylacetamide), poly(N-vinylphthalimide), poly(N-vinylsuccinimide), poly(N-vinylpyrrolidone), poly(N-vinylpiperidone) and poly(N-vinylcaprolactam) and copolymers thereof. Examples of poly(N-vinylamines) include poly(N-vinylimidazole) and poly(N-vinylcarbazole) and copolymers thereof. In addition to these vinyl monomers, other comonomers such as acrylates, methacrylates, unsaturated acids (acrylic acid, methacrylic acid), maleic anhydride, styrene and other vinyl aromatic monomers, acrylonitrile, methacrylonitrile and olefins such as ethylene, propylene, butylene and long-chain α-olefins may be used. Poly(vinyl alcohol) may be produced by saponification of poly(vinyl esters) such as poly(vinyl acetate) and copolymers of poly(vinyl acetate). The poly(vinyl alcohol) group can further react with different aldehydes and ketones to produce poly(vinyl alcohol acetals) such as poly(vinyl alcohol butyral). Aldehydes that can be used are formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, pivalaldehyde, glyoxylic acid and benzaldehyde. Poly(vinyl alcohol butyral) is typically a terpolymer comprising the residues of vinyl acetate, vinyl alcohol and cyclic butyral groups. The characteristics of poly(vinyl alcohol butyral) and related poly(vinyl alcohol acetals) include degree of acetalization, residual hydroxyl content, residual acetate content and molecular weight. In addition, other polymers can include polysaccharides such as chitosan, chitin, sodium carboxymethyl cellulose, cellulose acetate, sodium alginate, etc. For example, a binder can include poly(vinyl alcohol butyral) or a binder of similar types, such as other poly(vinyl alcohol acetals), such as poly(vinyl formaldehyde), poly(vinyl acetaldehyde), poly(vinyl benzaldehyde), and optionally include any comonomer listed above. When poly(vinyl butyral) or similar compositions are used as binders, they may optionally be functionalized.

[0063] Functionalized poly(vinyl butyral) binder materials can be prepared by methods such as the reaction between residual hydroxyl functional groups of poly(vinyl butyral) and electrophilic reagents such as carboxylic acids, anhydrides or isocyanate functional materials. In the case of the reaction between residual hydroxyl groups and cyclic anhydrides, side chain carboxylic acids can be formed. Reactions such as these can be carried out in solution and catalyzed using a suitable catalyst.

[0064] Functionalized poly(vinyl butyral)s can have properties and characteristics that can be controlled by the components of the reaction. Due to the functionalization process, the base poly(vinyl butyral) polymer can be changed so that the molecular weight of the polymer increases. In addition, by changing the functionality, the thermal transitions of the material, such as the glass transition temperature, can be changed. Due to the functionalization process, the hydroxyl equivalent weight is generally reduced, while the acid number may increase. Therefore, the functionalized poly(vinyl butyral) can also be more or less hydrophobic compared to the original material, depending on the functionality added. In addition, due to the added functional groups, such as carboxylic acids, the functionalized poly(vinyl butyral) can provide ionic interactions with other coating components.

[0065] When used in supercapacitor electrode coatings, functionalized poly(vinyl butyral) binders can provide advantages including increased adhesion to activated metal oxide / activated carbon particles, carbon within the coating and / or current collector, increased dispersion of the material within the coating during slurry preparation, and increased hydrophilicity.

[0066] Supercapacitor electrode coatings can be produced by combining or mixing metal oxide particles and carbon particles produced separately, or by producing one type of particles and then producing another type of particles. For example, as described more fully below, carbon particles such as graphene carbon nanoparticles can be initially provided in an aqueous dispersion, followed by the production of metal oxide particles such as manganese oxide in an aqueous dispersion containing preformed graphene carbon nanoparticles. Spray drying techniques can be used to produce active composite particles and / or coatings of the present invention. Spray drying involves passing a solution or slurry through a small nozzle, which atomizes the solution or slurry by hot gas. The hot gas is responsible for rapidly drying a single atomized particle at a high temperature with minimal residence time, removing volatile solvents and producing dry spherical particles of a solid material composed of non-volatile materials from the original solution or slurry. The final dried particles are then collected. A slurry of an activated metal oxide particle composite with a carbon-based carrier and a polymer material can be delivered by a spray drying nozzle, atomized from the nozzle, rapidly dried by hot air, and collected. After the spray drying of the slurry is completed, the final active material powder can be collected for further processing into an electrode coating. Spray drying allows the formation of a relatively uniform particle size consisting of a substantially uniform mixture of activated metal oxide, carbon-based support and polymeric material, preventing the formation of activated metal oxide agglomerates typically observed in conventional oven drying. The lack of large agglomerates of activated metal oxide particles can be attributed to the rapid drying properties of spray drying, which limits the time typically required for agglomerates of metal oxide to form and forces them to dry into a uniform mixture with the carbon support and polymeric material. For example, an aqueous solution comprising activated metal oxide particles and carbon-containing support particles can be spray dried to produce active composite particles.

[0067] Supercapacitor electrode coatings can be deposited on various types of substrates used in supercapacitors. For example, the coating can be deposited on current collector plates, foils, meshes, foams, etc. Suitable current collector substrates can be made of metals such as nickel, stainless steel (e.g., 316 stainless steel, 304 stainless steel), aluminum, copper, and titanium, as well as other conductive materials such as graphite, carbon fiber, etc. Any suitable type of coating process can be used, such as spraying, roller coating, brushing, additive manufacturing, etc.

[0068] When the coating is formed by an additive manufacturing process, such process may include any suitable process such as material jetting, binder jetting, directed energy deposition, material extrusion, sheet lamination, powder bed fusion, barrel photopolymerization, etc. Material jetting is an additive manufacturing process in which droplets of feedstock material are selectively deposited. The feedstock material can be deposited layer by layer until a coating of desired thickness is formed. Binder jetting is an additive manufacturing process in which a liquid binder is selectively deposited to join powdered material. The powdered material can be spread in a thin layer on a printing plate. Droplets of binder can be deposited into the powder bed to bind the powder at the location of the droplets. After one layer is completed, the printing plate can be lowered and another layer of powdered material can be spread on the printing plate. The process is repeated until the coating is complete.

[0069] The supercapacitor electrode coating may have a controlled thickness, such as greater than 20 microns, or greater than 50 microns, or greater than 70 microns. The electrode coating may have a thickness of at most 500 microns, such as at most 350 microns or at most 200 microns. Typical electrode coating thicknesses may be in the range of 20 to 500 microns, such as 50 to 350 microns or 70 to 200 microns.

[0070] Supercapacitor electrode coating thickness can also be measured in terms of weight per unit surface area. Electrode coating thickness can typically be greater than 1 mg / cm 2 , for example, greater than 3 mg / cm 2 or greater than 5 mg / cm 2 The electrode coating thickness can be up to 50 mg / cm 2 , for example up to 20 mg / cm 2 or up to 10 mg / cm 2 The electrode coating thickness can usually be between 1 and 50 mg / cm 2 , or 3 to 20 mg / cm 2 , or 5 to 10 mg / cm 2 within the range.

[0071] The supercapacitor electrode coating can have a controlled porosity, for example, a porosity of at least 20 volume percent or at least 40 volume percent or at least 60 volume percent. A porosity of up to 90 volume percent, or up to 80 volume percent, or up to 75 volume percent can be provided. The porosity of the electrode coating can generally be in the range of 20 to 90 volume percent, for example 50 to 80 volume percent, or 60 to 75 volume percent. The porosity can be measured by standard techniques known to those skilled in the art. For example, the relative density of all components of the coating can be calculated, the total volume of the components can be determined by conventional imaging techniques using commercially available software, the total volume of the coating can be determined by measuring the thickness and other dimensions of the film coating, and the porosity expressed in volume percent can be calculated thereby.

[0072] Due to the controlled agglomeration of activated metal oxide particles, activated carbon particles and polymer dispersants, the supercapacitor electrode coating can have a controlled microstructure, so that uniformity of materials and microstructure can be achieved. The proximity of the particle surface to the electrolyte may be due to the space between the MnO2|GNPs, binders and CNTs in the particles, which may exist because the MnO2|GNPs are prevented from agglomerating with each other in a manner that hinders the surface from approaching the electrolyte. If the MnO2|GNP is combined with another MnO2|GNP particle by agglomeration, the surface in direct contact with the other particle may not be available to the electrolyte, thereby reducing the capacitance. By spray drying, the surfaces of the MnO2|GNP particles can be inhibited from combining with each other, but can be fixed to a position that makes the surface of the primary particles more exposed to the electrolyte within the secondary particles, thereby allowing these surfaces to be more close to the electrolyte.

[0073] The supercapacitor electrode coating may comprise a substantially uniform distribution of active composite particles and / or conductive carbonaceous particles, for example, throughout the thickness of the coating. Alternatively, the active composite particles and / or conductive carbonaceous particles may be distributed non-uniformly in a gradient structure throughout the thickness of the coating. For example, the active composite particles and / or conductive carbonaceous particles may be provided at a higher concentration or loading on or near the surface of the electrode coating, or conductive carbonaceous particles such as carbon black may be provided at a higher concentration on or near the bottom of the coating near the conductive substrate.

[0074] Before the supercapacitor electrode coating is deposited on the substrate, the substrate can be pretreated. For example, for the cathode coating, the current collector substrate can be pretreated by processes such as acid treatment to remove the oxide layer and applying an organic coating to improve the adhesion of the supercapacitor electrode coating and prevent oxidation or reduction electrochemical reactions from occurring on the current collector surface. The native oxide present on the metal current collector can be removed by immersion in an acidic solution (such as hydrochloric acid, hydrofluoric acid or oxalic acid). The pH value of these solutions can be in the range of 0 to 4. The removal of the current collector oxide layer can be accelerated by applying an electrochemical bias. For example, a 5V electrochemical potential can be applied to a substrate immersed in an acid solution for 2 minutes.

[0075] After deoxidation of the metal substrate surface, the organic coating can be applied to the surface using a wet application method such as blade coating. The organic coating formulation can contain a carbon material such as carbon black, graphite, or a combination of the two blended with a fluoropolymer binder such as polyvinylidene fluoride, an acrylic polymer, and a melamine crosslinker dispersed in an organic solvent. For example, the binder may include fluoropolymers and addition polymers as described in paragraphs

[0020] to

[0023] ,

[0037] to

[0049] ,

[0166] , and

[0173] of U.S. Patent Application Publication No. US2020 / 0176777. The carbon content is typically 70 to 95 weight percent of the solid, with the remainder being polyvinylidene fluoride and 0.5 to 2 weight percent of melamine. The films can then be cured at 120°C for 4 minutes. When applied to a deoxidized current collector, the pretreatment coating is typically 0.2 to 0.6 mg / cm 2 range and can be used without further processing.

[0076] When activated metal oxide particles and activated carbon particles are combined in a rapid drying process, a slurry or suspension of activated metal oxide particles and activated carbon particles in a liquid carrier can be provided, which is rapidly dried to form a powder of a composite particle comprising activated metal oxide and activated carbon. For example, each composite particle can include a combination of activated metal oxide particles and graphene carbon nanosheets, wherein the activated metal oxide particles contact each other to form a continuous or interconnected network of activated metal oxide particles, and the graphene carbon nanosheets are distributed throughout the composite particles. Alternatively, the graphene carbon nanosheets can contact each other to form a continuous or interconnected network of graphene carbon in the composite particles. Therefore, each composite particle can include a plurality of activated metal oxide particles and a plurality of graphene carbon nanosheets, which are adjacent, adhered or agglomerated together to form a composite particle. In such agglomerated composite particles, activated metal oxide particles and graphene carbon nanosheets can be evenly distributed in each particle, or unevenly distributed.

[0077] The following examples are provided for illustrative purposes, however, they should not be considered limiting.

[0078] Examples

[0079] Preparation of water-based graphene dispersions

[0080] Using a pigment to dispersant ratio of 14 / 1, an aqueous dispersion of 1500g of graphene carbon particles was prepared, with a total solid loading of 3 to 6 weight percent depending on the formulation. The graphene carbon source includes thermally produced graphene carbon nanoparticles sold under the names Raymor PureWave graphene nanosheets and XG Sciences M25 exfoliated graphite graphene nanosheets. Dispersants are typically polyvinylpyrrolidone with a molecular weight close to 1.3MDa. First, the dispersion was mixed between 500 and 1000rpm with Cowles blades in an appropriate amount of water for about 60 minutes, then transferred to an Eiger grinder with a 250mL grinding chamber volume. The grinding media used during the grinding step was about 1.0mm (Zirmil Y) in size, and added to the grinding chamber to occupy about 80% of the total volume. The dispersion was ground at 2000rpm for 15 minutes.

[0081] Table 1 Particle size distribution of various graphene dispersions in aqueous solution with P:B=14

[0082]

[0083] Particle sizes were collected using a Mastersizer 2000 with a Hydro 2000S(A) attachment using the Universal (Spherical) analysis model.

[0084] The rheological curves of the dispersions listed in Table 1 are provided in Figure 1 middle. Figure 1 Rheological curves for (·) Raymor PureWave graphene, (+) XG Sciences M25 graphene, 3 weight percent aqueous graphene dispersions of Raymor PureWave graphene and XG Sciences M25 graphene in (■) 1:1 and (▲) 1:3 weight ratios, and 6 weight percent aqueous dispersion of (◆) 1:3 Raymor PureWave graphene and XG Sciences M25 graphene.

[0085] The viscosity measurements of the dispersions listed in Table 1 are provided in Figure 2 middle. Figure 2Included are viscosity measurements of aqueous dispersions containing varying amounts of XG Sciences M25 exfoliated graphite graphene carbon, Raymor PureWave graphene carbon, and dispersant at either 3 weight percent or 6 weight percent total solids.

[0086] Figure 1 The rheological curves and Figure 2 The viscosity measurements shown in were measured by standard procedures using an Anton Paar MCR 302 and a CP50-1TG measuring cone. Viscosity measurements at a shear rate of 10 Hz can be used for comparison of the dispersion rheology.

[0087] The instability index graphs for the dispersions listed in Table 1 provide Figure 3 Instability index properties were measured as described above. Figure 3 Instability index including 3 weight percent aqueous graphene dispersions containing (·) Raymor PureWave graphene, (+) XG Sciences M25 graphene, (■) 1:1 and (▲) 1:3 weight ratios of Raymor PureWave graphene and XG Sciences M25 graphene blends, and (◆) 1:3 6 weight percent aqueous dispersions of Raymor PureWave graphene and XG Sciences M25 graphene. The instability index is measured by the following procedure.

[0088] The instability index analysis can be used for the accelerated assessment of long-term stability, which measures the dispersion sedimentation at a specified centrifugal speed and temperature. Unless otherwise specified in the specification or claims, the "instability index" is measured as follows: the dispersion sample is loaded in a centrifuge and a pulsed near-IR light of 865nm is transmitted through the sample. During the centrifugation process, the near-IR light transmitted through the sample is measured with a dispersion analyzer sold by LuM GmbH as LUMiSizer model 611. The measurement was carried out at 25°C and a centrifugal speed of 4000rpm, and the relative centrifugal acceleration (RCA) was 2202 during the centrifugation process of about 20 to 35 minutes. The transmission level at the beginning of the centrifugation was compared with the transmission level at the end of the 20-minute period, and the instability index was calculated by normalizing the change in the transmission level recorded. The reported instability index is a dimensionless number between 0 and 1, where "0" indicates that the particle concentration has not changed, and "1" indicates that the dispersion has completely phase separated. A relatively unstable dispersion will show a higher transmittance increase due to significant phase separation of the graphene carbon nanoparticles and the solvent, while a relatively stable dispersion will show a lower transmittance increase due to less phase separation. The instability index can be calculated using Software tool calculation. In the article entitled "Instability Index" (T. Detloff, T. Sobisch, D. Lerche, Instability Index, Dispersion Letters Technical, T4 (2013) 1-4, updated 2014) provides information on A description of how the software tool determines the instability index is incorporated herein by reference. The instability index of the aqueous dispersion of graphene carbon nanoparticles can generally be less than 0.7, such as less than 0.6, or less than 0.5, or less than 0.4, or less than 0.3, or less than 0.1.

[0089] Figures 1 to 3 The rheological changes observed when expanded or exfoliated graphite graphene particles are dispersed together with turbostratic, thermally generated graphene carbon particles, and the increased stability of the graphene carbon in solution obtained when a 1:1 w / w ratio of expanded graphene and turbostratic, thermally generated graphene carbon particles is used in solution and then the particles are used as a conductive support for the growth of activated metal oxides such as manganese dioxide are demonstrated.

[0090] Synthesis of MnO2|GNPs

[0091] Potassium permanganate (182.7 g, 1.16 moles) was dissolved in 2818 g of deionized water. Separately, benzyl alcohol (375.1 g, 3.47 moles) was added to a 500 mL addition funnel and assembled into a 5 L multi-necked flask. A water-based graphene dispersion (3 weight percent graphene, total graphene / polyvinylpyrrolidone dispersant ratio of 14:1) was added to a 5 L multi-necked round bottom flask (374 g total dispersion, 11.97 g total solid material) and was heated with a pneumatic motor mounted on a 1200 rpm flask. The stirring blade stirs at a speed between 100 and 500 rpm. During the reaction, the speed of the stirring blade can be adjusted between 100 and 1000 rpm as needed to keep the material fully cooled and dispersed. The flask is then placed in an ice bath and benzyl alcohol is added at a rate of about 6 mL / min for 5 minutes. Then, potassium permanganate is added at a rate of about 50 mL / min using a peristaltic pump and a silicone tube. Nitrogen is added to the reaction flask throughout the experiment to help cool and remove oxygen from the reaction atmosphere. The reaction temperature is maintained at about 15°C to 25°C throughout the reaction. It takes about 1 hour to completely add the reagents to the flask, after which the reaction is allowed to continue stirring at about room temperature for another hour to ensure complete reaction. The final reaction is then filtered and washed with DI water and isopropanol, followed by a final rinse with DI water, and then the hydrated product is collected. The total solid content of the powder is measured to determine the hydration level. In some instances, the intermediate powder is dried at 100°C under vacuum for at least 4 to 6 hours.

[0092] After collecting the product of potassium permanganate reduction, a portion of the powder was resuspended in an aqueous solution containing poly(acrylic acid) (Sigma Aldrich, 450 kg / mol) (denoted as KPAA) and carbon nanotubes (C-Nano LB217-54, denoted as CNT) neutralized to pH 7 with potassium hydroxide to obtain a total solid dispersion of approximately 34 weight percent. The weight percentage can be adjusted as needed to accommodate changes in viscosity to ensure adequate mixing of the materials, ranging from 5 to 40 weight percent. This solution of KPAA and CNT is prepared before adding the powder. For example, 11.6 g of a 13 weight percent KPAA solution is placed in a small plastic container with a lid along with 20.0 g of a 6.25 weight percent CNT dispersion (1.25 weight percent dispersant) containing 5 weight percent CNT. The solution is thoroughly mixed at 2000 rpm in a small planetary THINKY mixer for about 2 to 5 minutes. The solution was then transferred to a larger plastic container with an appropriately sized Cowles blade mixer and 264 g of MnO2|GNP hydrated powder was incorporated (powder measured to be 37 weight percent solids, 63% water). Additional deionized water was added if necessary to ensure a shear-thinning, relatively high viscosity slurry was stirred between 1000 and 1500 rpm. When the solution was diluted with 704 g of deionized water, the solution was allowed to mix for 1 hour and then the stirring speed was reduced to between 250 and 750 rpm. The solution was stirred at 250 to 750 rpm for an additional hour. If desired, the dispersion could also be probe sonicated at 80% power for 1 hour (Branson 550) and cooled in an ice bath. Before the next step, a solution of 0.4 g of a carbodiimide crosslinker (40 weight percent, Carbodilite V-02-L2) was prepared and allowed to stir for at least 10 to 20 minutes.

[0093] The solution was then spray dried using a micro spray dryer (Büchi) with an inlet temperature set at 220° C., an aspirator set at 60% and a pump speed of 18% to 26% to control the outlet temperature at approximately 90° C. to 95° C. In some examples, the resulting powder was further dried at 150° C. under vacuum for at least 4 to 6 hours.

[0094] Figure 4 Included are rheological data for dispersions containing approximately equal concentrations of MnO2, graphene, conductive carbon, and binder measured as described above, wherein (O) commercially available activated MnO2 physically mixed with 1:1 w / w ratio of PureWave graphene and M25 graphene, (Δ) synthetically grown MnO2 in the presence of 1:1 w / w ratio of PureWave graphene and M25 graphene, which was dried under vacuum at 100°C for at least 4 hours, and (□) synthetically grown MnO2 in the presence of 1:1 w / w ratio of PureWave graphene and M25 graphene, which was formulated with an acrylic binder and carbon nanotubes prior to spray drying. All samples contained approximately 69 to 71 weight percent MnO2, 7 to 8 weight percent graphene, 10 to 11 weight percent of a binder consisting of 4:1 w / w ratio of PVBA and PVP, and approximately 10 to 12 weight percent of a conductive carbon black such as Super P. The solvent was butyl cellosolve and all slurries had a total solids content of 33.5 weight percent.

[0095] Figure 5 is a cross-sectional scanning electron microscope image of a MnO2+GNP cathode coating on a carbon-coated Ni foil. The carbon coating contains both Super P and graphite at the Ni interface.

[0096] Figure 6 is a cross-sectional scanning electron microscope electron dispersion spectroscopy (SEM-EDS) image of a MnO2+GNP cathode coating on carbon-coated Ni foil, highlighting the inhomogeneous dispersion of (upper left) carbon, (upper right) oxygen, (lower left) manganese, and (lower right) nickel.

[0097] Figure 7 is a cross-sectional scanning electron microscope image of a MnO2|GNP (not spray dried) cathode coating on a carbon coated Ni foil. The carbon coating contains both Super P and graphite at the Ni interface.

[0098] Figure 8is a cross-sectional scanning electron microscope electron dispersive spectroscopy (SEM-EDS) image of a MnO2|GNP (not spray dried) cathode coating on carbon-coated Ni foil, highlighting the dispersion of (upper left) carbon, (upper middle) oxygen, (upper right) potassium, (lower left) manganese, and (lower right) nickel.

[0099] Fig. 9 is a cross-sectional scanning electron microscope image of a spray-dried MnO2|GNP cathode coating on a carbon-coated Ni foil. The carbon coating contains both Super P and graphite at the Ni interface.

[0100] Fig.10 is a cross-sectional scanning electron microscopy electron dispersive spectroscopy (SEM-EDS) image of a spray-dried MnO2|GNP cathode coating on carbon-coated Ni foil, highlighting the uniform dispersion of (top left) nickel, (top right) carbon, (bottom left) potassium, (bottom middle) manganese, and (bottom right) oxygen.

[0101] Table 2

[0102] ICP results highlighting the metal content of each MnO2|GNP

[0103] Active materials containing various graphene sources.

[0104]

[0105] No. 1 cathode binder

[0106] In a four-necked round bottom flask, 120 grams of poly (vinyl butyral-co-vinyl alcohol-co-vinyl acetate) [Mw 90,000–120,000] [88 weight percent butyraldehyde, 11 weight percent hydroxyl, 1 weight percent acetate], 360 grams of 2-butoxyethanol acetate, 27 grams of succinic anhydride, and 0.15 grams of 1,4-diazabicyclo [2.2.2] octane were added and the flask was equipped with a mechanical stirring blade, a thermocouple, and a reflux condenser. The flask was heated to a set point of 100° C. under a nitrogen atmosphere. The reaction was then held at 100° C. for 4 hours. The reaction temperature was subsequently raised to 120° C. for 4 hours. After this hold, the reaction was cooled and poured into a suitable container. The final measured solids of the resin were determined to be 30.4% solids.

[0107] No. 2 cathode binder

[0108] In a four-necked round bottom flask, 104 grams of Mowital B30-T, 312.5 grams of 2-butoxyethanol acetate, 30 grams of succinic anhydride and 0.13 grams of 1,4-diazabicyclo[2.2.2]octane were added and the flask was equipped with a mechanical stirring blade, a thermocouple and a reflux condenser. The flask was heated to a set point of 120°C under a nitrogen atmosphere. The reaction was then held at 120°C for 8 hours. The reaction temperature was then reduced to 90°C and 223 grams of 2-butoxyethanol was added to the flask. The reaction mixture was stirred for 2 hours. After this hold, the reaction was cooled and poured into a suitable container. The final measured solids of the resin were determined to be 18.4% solids.

[0109] No. 3 cathode binder

[0110] In a four-necked round bottom flask, 92.4 grams of Mowital B30-T, 462 grams of 2-butoxyethanol acetate, 48 grams of succinic anhydride, and 0.12 grams of 1,4-diazabicyclo[2.2.2]octane were added, and the flask was equipped with a mechanical stirring blade, a thermocouple, and a reflux condenser. The flask was heated to a set point of 100°C under a nitrogen atmosphere. The reaction was then held at 100°C for 6 hours. The reaction temperature was then reduced to 90°C, and 224 grams of 2-butoxyethanol were added to the flask. The reaction mixture was stirred for 30 minutes. After this hold, the reaction was cooled and poured into a suitable container. The final measured solids of the resin were determined to be 16.5% solids.

[0111] No. 4 cathode binder

[0112] In a four-necked round bottom flask, 120 grams of poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate) [Mw 90,000–120,000] [88 weight percent butyraldehyde, 11 weight percent hydroxyl, 1 weight percent acetate], 360 grams of 2-butoxyethanol acetate, 27 grams of succinic anhydride, and 0.15 grams of 1,4-diazabicyclo[2.2.2]octane were added and the flask was equipped with a mechanical stirring blade, a thermocouple, and a reflux condenser. The flask was heated to a set point of 100° C. under a nitrogen atmosphere. The reaction was then held at 100° C. for 8 hours. 81.5 grams of 2-butoxyethanol was subsequently added to the flask. The reaction mixture was stirred for 15 minutes. After this hold, the reaction was cooled and poured into a suitable container. The final measured solids of the resin were determined to be 24.6% solids.

[0113] Carbon Pretreatment Recipes

[0114] 5.2 g of Timcal graphite and carbon super P conductive carbon black (MTI) were added to 37.15 g of triethyl phosphate solution containing 2 weight percent PVDF and acrylic copolymer mixture. The dispersion was mixed manually for 30 seconds and then mixed in a centrifugal mixer at 2000 rpm, mixing every 2 minutes for a total of 6 minutes. After the carbon was fully dispersed, 0.4 g of triethyl phosphate solution containing 10 weight percent melamine formaldehyde crosslinker was added and mixed in a centrifugal mixer at 2000 rpm for 15 seconds. The carbon dispersion was coated on Ni foil using a 5 mil blade rod and then cured at 150°C for 10 minutes to obtain 0.7 mg cm -2 of load.

[0115] MnO2|GNP cathode electrode formulation – 80 / 10 / 10 “active” / conductive carbon / binder

[0116] The sample of MnO2|GNP without spray drying, 15 5-mm yttrium-infused zirconia grinding beads were added to the mixer to ensure the proper decomposition of the particles. 0.67g of carbon super P conductive carbon black (MTI) was added to 5.26g of butyl cellosolve and 1.26g of butyl cellosolve solution containing 11 weight percent polyvinyl pyrrolidone (1.3MDa, Aldrich). The dispersion was mixed at 2000rpm in a centrifugal mixer, mixed once every 2 minutes, and mixed for a total of 4 minutes or until fully dispersed. After mixing, the black dispersion was diluted with 5.26g and mixed for 2 minutes at 2000rpm in a centrifugal mixer. After dilution, 2.18g of butyl cellosolve / butyl cellosolve solution containing 25 weight percent acid-functionalized polyvinyl butyral copolymer resin (PVBA) was added, and mixed for 2 minutes at 2000rpm in a centrifugal mixer. Once fully dispersed, 5.36 g of MnO2|GNPs were added and the final slurry was mixed in a centrifugal mixer at 2000 rpm, mixing every 2 minutes for a total of 6 minutes or until fully dispersed. In the case of commercial MnO2 or synthetic MnO2|GNPs that were not spray dried, the milling time was stopped after a total of 12 minutes of milling. The final dispersion was coated onto a carbon pretreated Ni foil (25 μm Ni foil with a carbon pretreatment layer of approximately 15 to 20 μm thick, with a loading of 0.7 mg cm) using a draw bar thickness range of 5 to 10 mils, preferably 6 to 8 mils. -2 ) and subsequently cured at 55° C. and 120° C. for two minutes at each temperature. The final cured film is then calendered to the desired porosity, typically 60 to 75 volume percent.

[0117] Fig.11 1.27cm including active material 2Capacitance versus current density (j) of electrodes with active materials including (○) commercial manganese (IV) oxide mixed with a 1:1 w / w blend of PureWave and XG Sciences graphene in a weight ratio of 9:1 MnO2:graphene, (Δ) MnO2|GNP raw powder not blended with CNT or KPAA and not spray dried, and (□) MnO2|GNP spray dried with CNT and KPAA. The coating formulation was 80 / 10 / 10 "active": carbon black:binder. The binder in this system was PVBA / PVP in a 4:1 w / w ratio, and the carbon black source was Super P. After calendering, the final film porosity was measured to be approximately 73 volume percent. Each electrochemical cell was cycled between 0 and 1.25 V versus Ag / AgCl using a Pt mesh counter electrode and an Ag / AgCl (saturated KCl) reference electrode.

[0118] Fig.12 Including 1.27cm of MnO2|GNP 2 Capacitance versus current density (j) plot of an electrode having a formulation of 88 / 2 / 10 active / carbon black / binder, where the graphene used in the active material is estimated to be a 9:1 w / w ratio of MnO2 and a graphene source, the graphene source being PureWave graphene, XG Sciences M25 graphene, or a 1:1 w / w ratio of PureWave and M25 graphene. The binder in this system is a 4:1 w / w ratio of PVBA / PVP, and the carbon black source is Super P. Each electrochemical cell was cycled between 0 and 1.25 V vs. Ag / AgCl using a Pt mesh counter electrode and an Ag / AgCl (saturated KCl) reference electrode.

[0119] Fig.13 1.27 cm of MnO2|GNPs were synthesized using (black, open circles) benzyl alcohol, (dark grey, triangles) ethylene glycol, or (light grey, squares) manganese(II) acetate as a reducing agent in solution with potassium permanganate, followed by spray drying with potassium-modified polyacrylic acid and carbon nanotubes. 3 Capacitance of the electrode versus current density (j). The coatings were prepared with a 80 / 10 / 10 active material / carbon black / binder formulation using Super P as the carbon black source and PVBA / PVP (4:1 w / w) as the binder.

[0120] Fig.14 1.27 cm of MnO2|GNPs comprising a formulation of 80 / 10 / 10 active / carbon black / binder 2Capacitance versus current density (j) of the electrode, where the graphene used in the active material is estimated to be a graphene source of MnO2 and PureWave Graphene in a 4:1 w / w ratio. The binder in this system is PVBA / PVP in a 4:1 w / w ratio, and the carbon black source is Super P. Each electrochemical cell was cycled between 0 and 1.25 V vs. Ag / AgCl using a Pt mesh counter electrode and an Ag / AgCl (saturated KCl) reference electrode.

[0121] Figures 11 to 14 The data shown in were generated by testing the coating in half-cell form with a Ag / AgCl (saturated KCl) reference electrode and a Pt mesh counter electrode in a 7 m NaClO4 acetonitrile / water in salt (AWiS) electrolyte. The cell was charged at a constant current between 1 and 10 A / g and then allowed to rest for 1 minute, then discharged symmetrically to the charge rate and allowed to rest for 10 minutes. The charge passed during discharge is divided by the change in discharge voltage.

[0122] Fig.15 Included are cyclic voltammetry of full cells using an 80 / 10 / 10 active material / carbon black / binder formulation, with (dark grey, dash-dotted line) a symmetric YP-80F activated carbon electrode on Al foil using PVDF as a binder in 1 M TEABF4 in acetonitrile, (light grey, dash-dotted line) a symmetric YP-80F activated carbon electrode on bare Ni foil using chitosan as a binder at the anode and carbon-coated Ni foil and PVBA / PVB (4:1 w / w) binder at the cathode in 7 M NaClO4 acetonitrile / water in salt electrolyte, and (black, solid line) asymmetric YP-80F / MnO2|GNP electrode on bare Ni foil using YP-80F activated carbon as the active material and chitosan as a binder at the anode and carbon-coated Ni foil using MnO2|GNPs as the active material and PVBA as a binder at the cathode in 7 M NaClO4 acetonitrile / water in salt (AWiS) electrolyte. All systems used Super P as the conductive carbon black source. Fig.15The data shown in the are generated by first assembling the related and charge-balanced anode and cathode electrodes into 2032 stainless steel button cells with a polyolefin-based separator and an appropriate electrolyte (1M tetraethylammonium tetrafluoroborate in anhydrous acetonitrile or 7 molar sodium perchlorate acetonitrile / water-in-salt electrolyte). For cells tested using 1M TEABF4 in acetonitrile, all cells were properly dried and assembled in a glove box under an Ar atmosphere. For cells tested with acetonitrile / water-in-salt electrolyte, the electrolyte contained a 2:3 acetonitrile / water molar ratio and the cells were prepared under ambient conditions. The voltage of these cells was then scanned by cyclic voltammetry at a rate of 1 mV / s using a Bio-Logic VSP potentiostat until the desired voltage was reached.

[0123] Fig.16 1.27 cm of MnO2|GNPs comprising a formulation of 80 / 10 / 10 active material / carbon black / binder 2 Capacitance versus current density (j) plot of the electrode, where the graphene used in the active material is estimated to be a graphene source of MnO2 and PureWave Graphene at 4:1 w / w. The binder in this system is PVBA / PVP at a 4:1 w / w ratio, and the carbon black source is Super P. Each electrochemical cell was cycled between 0 and 1.25 V vs. Ag / AgCl using a Pt mesh counter electrode and an Ag / AgCl (saturated KCl) reference electrode. Fig.16 as well as Figures 11 to 14 The data shown in were generated by applying constant current charge and discharge to the working electrode in a flooded half-cell electrochemical cell at various current densities using a Bio-Logic VSP potentiostat. In all cases of the half-cell tests described herein, the reference electrode was Ag / AgCl (saturated KCl) and the counter electrode was Pt. The electrolyte used was a 7 molar sodium perchlorate acetonitrile / water in salt electrolyte AWiS, with an acetonitrile / water molar ratio of 2:3.

[0124] Devices comprising electrode coatings of the present invention can achieve a capacitance of at least 100 F / g, such as at least 140 F / g or at least 150 F / g. The capacitance can be in the range of 100 to 300 F / g, or 140 to 250 F / g, or 150 to 200 F / g. The current density can be in the range of 0.1 to 30 A / g, or 0.5 to 20 A / g, or 1 to 10 A / g, where the mass in grams refers to the mass of active material on the electrode.

[0125] Fig.17(Left) Composite resistivity and (right) interface resistivity measurements of supercapacitor cathode coatings on Ni foil under the 88 / 2 / 10 formulation of MnO2|GNP / Super P / binder (modified polyvinyl butyral). The resistivity of the electrode coating was measured using a HIOKI electrode resistor meter (HIOKI RM26111). The composite volume resistivity and interfacial contact resistivity were measured after calibrating the instrument with a gold-coated plate (short circuit) and a bare plastic plate (open circuit) provided by the manufacturer and entering the known resistivity of the metal current collector. Resistivity data were collected at three different areas of the electrode and averaged to ensure accuracy. The resistivity of the film can affect charge transport in the coating, where a higher resistivity means poor conductivity and therefore slow charge transport, and vice versa for a lower resistivity. Better charge transport (lower resistivity) in the electrode coating enables power performance (fast charge-discharge) of the electrode.

[0126] For the purpose of detailed description, it should be understood that, unless clearly indicated to the contrary, the present disclosure can take various alternative variations and step sequences. In addition, except in any operating example or in the case of additional indication, all numerals such as those numerals of representation value, amount, percentage, range, sub-range and fraction etc. can be interpreted as starting with the word "about", even if the term does not clearly appear. Therefore, unless indicated to the contrary, the numerical parameter set forth in the following specification and the appended claims is an approximate value that can be changed according to the desired properties to be obtained by the present disclosure. At least, and not attempting to limit the application of the principle of equivalents to the scope of the claim, each numerical parameter should at least be explained according to the number of reported significant figures and by applying common rounding techniques. In the case of closed or open numerical ranges described herein, all numerals, values, amounts, percentages, sub-ranges and fractions covered in this numerical range or by this numerical range should be considered as specifically included in the original disclosure of the application and belong to the original disclosure of the application, as these numerals, values, amounts, percentages, sub-ranges and fractions have all been clearly written out.

[0127] Notwithstanding that the numerical ranges and parameters setting forth the broad scope are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0128] In addition, it should be understood that any numerical range described herein is intended to include all subranges contained therein. For example, a range of "1 to 10" is intended to include all subranges between (and including the endpoints) the recited minimum value of 1 and the recited maximum value of 10, i.e., having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0129] As used herein, unless otherwise specified, plural terms may encompass their singular counterparts, and vice versa, unless otherwise specified. In addition, in this application, unless otherwise specifically specified, the use of "or" means "and / or", even though "and / or" may be explicitly used in certain circumstances.

[0130] As used herein, "comprising," "containing," and similar terms are understood in the context of this application to be synonymous with "comprising," and are therefore open-ended and do not exclude the presence of additional undescribed or unrecited elements, materials, components, or method steps. As used herein, "consisting of" is understood in the context of this application to exclude the presence of any unspecified elements, ingredients, or method steps. As used herein, "consisting essentially of" is understood in the context of this application to include the specified elements, materials, ingredients, or method steps "as well as those elements, materials, ingredients, or method steps that do not materially affect the basic and novel characteristics."

[0131] As used herein, the terms "on", "onto", "applied on", "applied onto", "formed on", "deposited on", "deposited onto" mean formed, covered, deposited, or provided on a surface but not necessarily in contact with the surface. For example, an electrodepositable coating composition "deposited on a substrate" does not exclude the presence of one or more other intermediate coatings of the same or different composition positioned between the electrodepositable coating composition and the substrate.

[0132] While specific examples of the present disclosure have been described above for purposes of illustration, it will be apparent to those skilled in the art that numerous changes may be made in the details of the disclosure without departing from the present disclosure as defined in the appended claims.

Claims

1. A coating for use as a supercapacitor electrode, the coating comprising: Active composite particles comprising activated metal oxide particles and carbonaceous support particles; and Conductive carbonaceous particles.

2. The coating of claim 1, wherein the activated metal oxide particles are grown on the carbon-containing support particles.

3. The coating of claim 1, wherein the activated metal oxide particles comprise manganese oxide, potassium manganese oxide, sodium manganese oxide, lithium manganese oxide, or a combination thereof.

4. The coating of claim 1, wherein the activated metal oxide particles comprise stoichiometric manganese oxide.

5. The coating of any one of claims 1 to 4, wherein the carbon-containing support particles comprise graphene carbon nanoparticles.

6. The coating of claim 5, wherein the graphene carbon nanoparticles comprise thermally generated graphene carbon nanoparticles.

7. The coating of claim 6, wherein the graphene carbon nanoparticles comprise exfoliated graphite graphene nanoparticles.

8. The coating of any one of claims 5 to 7, wherein the graphene carbon nanoparticles comprise carbon nanotubes.

9. The coating of any one of claims 1 to 8, wherein the activated metal oxide particles comprise at least 1 weight percent, or at least 50 weight percent, or at least 70 weight percent of the active composite particles.

10. The coating of any one of claims 1 to 9, wherein the activated metal oxide particles comprise at most 99 weight percent, or at most 95 weight percent, or at most 90 weight percent of the active composite particles.

11. The coating of any one of claims 1 to 10, wherein the activated metal oxide particles comprise 1 to 99 weight percent, or 50 to 95 weight percent, or 70 to 90 weight percent of the active composite particles.

12. The coating of any one of claims 1 to 11, wherein the carbon-containing support particles comprise at least 1 weight percent, or at least 5 weight percent, or at least 10 weight percent of the active composite particles.

13. The coating of any one of claims 1 to 12, wherein the carbon-containing support particles comprise at most 99 weight percent, or at most 50 weight percent, or at most 30 weight percent of the active composite particles.

14. The coating of any one of claims 1 to 13, wherein the carbon-containing support particles comprise 1 to 99 weight percent, or 5 to 50 weight percent, or 10 to 30 weight percent of the active composite particles.

15. The coating of any one of claims 1 to 14, wherein the conductive carbonaceous particles comprise carbon black, graphite, carbon nanotubes, graphene, activated carbon, or a combination thereof.

16. The coating of any one of claims 1 to 15, wherein the conductive carbon-containing particles comprise carbon black.

17. The coating of any one of claims 1 to 16, wherein the electrically conductive carbon-containing particles are activated.

18. The coating of claim 1, wherein the active composite particles further comprise a composite binder.

19. The coating of claim 18, wherein the composite binder comprises polyacrylic acid neutralized with potassium hydroxide.

20. The coating of claim 18 or 19, wherein the composite binder comprises at most 10 weight percent, or at most 5 weight percent, or at most 2 weight percent, and / or at least 0.01 weight percent, or at least 0.1 weight percent of the active composite particles.

21. The coating of any one of claims 1 to 20, wherein the active composite particles comprise at least 50 weight percent, or at least 60 weight percent, or at least 70 weight percent of the coating.

22. The coating of any one of claims 1 to 21, wherein the active composite particles comprise at most 99 weight percent, or at most 98 weight percent, or at most 95 weight percent of the coating.

23. The coating of any one of claims 1 to 22, wherein the active composite particles comprise 50 to 99 weight percent, or 60 to 98 weight percent, or 70 to 98 weight percent of the coating.

24. The coating of any one of claims 1 to 23, wherein the active composite particles have an average particle size of at least 100 nanometers, or at least 1 micrometer, or at least 2 micrometers.

25. A coating according to any one of claims 1 to 24, wherein the active composite particles have an average particle size of at most 100 microns, or at most 20 microns, or at most 10 microns.

26. The coating of any one of claims 1 to 25, wherein the active composite particles have an average particle size of 100 nanometers to 100 micrometers, or 1 to 20 micrometers, or 2 to 10 micrometers.

27. A coating according to any one of claims 1 to 26, wherein the conductive carbon-containing particles constitute at least 0.5 weight percent, or at least 1 weight percent, or at least 2 weight percent, or at least 4 weight percent, or at least 5 weight percent, or at least 8 weight percent of the coating.

28. The coating of any one of claims 1 to 27, wherein the conductive carbon-containing particles comprise at most 50 weight percent, or at most 30 weight percent, or at most 20 weight percent, or at most 15 weight percent, or at most 12 weight percent of the coating.

29. The coating of any one of claims 1 to 28, wherein the conductive carbon-containing particles comprise 0.5 to 50 weight percent, or 1 to 30 weight percent, or 2 to 20 weight percent, or 5 to 15 weight percent, or 8 to 12 weight percent of the coating.

30. The coating of any one of claims 1 to 29, wherein the coating further comprises a binder.

31. The coating of claim 30, wherein the binder comprises poly(vinyl esters), poly(vinyl alcohols), poly(vinyl acetals), poly(vinyl ethers), poly(N-vinyl amides), poly(N-vinyl lactams), poly(N-vinyl amines) and copolymers thereof, acrylates, methacrylates, unsaturated acids (acrylic acid, methacrylic acid), maleic anhydride, styrene and other vinyl aromatic monomers, acrylonitrile, methacrylonitrile and olefins, polysaccharides, and combinations thereof.

32. A coating according to claim 30 or 31, wherein the binder comprises poly(vinyl butyral).

33. The coating of claim 32, wherein the poly(vinyl butyral) is functionalized.

34. The coating of claim 33, wherein the poly(vinyl butyral) is functionalized with a cyclic anhydride.

35. The coating of any one of claims 30 to 34, wherein the binder comprises at least 0.01 weight percent, or at least 0.1 weight percent, or at least 1 weight percent, or at least 2 weight percent of the coating.

36. The coating of any one of claims 30 to 35, wherein the binder comprises at most 20 weight percent, or at most 15 weight percent, or at most 10 weight percent of the coating.

37. The coating of any one of claims 30 to 36, wherein the binder comprises 0.01 to 20 weight percent, or 0.1 to 20 weight percent, or 1 to 15 weight percent, or 2 to 10 weight percent of the coating.

38. The coating of any one of claims 1 to 37, wherein the conductive carbon-containing particles form an interconnected network in the coating.

39. The coating of any one of claims 1 to 38, wherein at least a portion of the active composite particles are separated from one another in the coating.

40. The coating of any one of claims 1 to 39, wherein at least a portion of the active composite particles are separated from each other by the conductive carbon-containing particles.

41. A coating according to any one of claims 1 to 40, wherein the coating has a thickness of at least 20 microns, or at least 50 microns, or at least 70 microns.

42. A coating according to any one of claims 1 to 41, wherein the coating has a thickness of at most 500 microns, or at most 350 microns, or at most 200 microns.

43. A coating according to any one of claims 1 to 42, wherein the coating has a thickness of 20 to 500 microns, or 50 to 350 microns, or 70 to 200 microns.

44. The coating according to any one of claims 1 to 43, wherein the coating has a g / cm 2 , or at least 3 mg / cm 2 , or at least 5 mg / cm 2 Thickness.

45. A coating according to any one of claims 1 to 44, wherein the coating has a maximum of 50 mg / cm 2 , or up to 20 mg / cm 2 , or up to 10 mg / cm 2 Thickness.

46. ​​The coating according to any one of claims 1 to 45, wherein the coating has a g / cm 2 , or 3 to 20 mg / cm 2 , or 5 to 10 mg / cm 2 Thickness.

47. A coating according to any one of claims 1 to 46, wherein the coating has a porosity of at least 20 volume percent, or at least 40 volume percent, or at least 60 volume percent.

48. A coating according to any one of claims 1 to 47, wherein the coating has a porosity of at most 90 volume percent, or at most 80 volume percent, or at most 75 volume percent.

49. A coating according to any one of claims 1 to 48, wherein the coating has a porosity of 20 to 90 volume percent, or 40 to 80 volume percent, or 60 to 75 volume percent.

50. An active composite particle for a supercapacitor electrode coating, the active composite particle comprising: activated metal oxide particles; and Carbonaceous support particles.

51. The active composite particle of claim 50, wherein the activated metal oxide particles are grown on the carbon-containing support particles.

52. The active composite particle of claim 50, wherein the activated metal oxide particles comprise manganese oxide, potassium manganese oxide, sodium manganese oxide, lithium manganese oxide, or combinations thereof.

53. The activated composite particle of claim 50, wherein the activated metal oxide particles comprise manganese oxide.

54. The active composite particle of claim 53, wherein the manganese oxide comprises MnO2.

55. The active composite particle of any one of claims 50 to 54, wherein the carbon-containing support particles comprise graphene carbon nanoparticles.

56. The active composite particle of any one of claims 50 to 55, wherein the graphene carbon nanoparticles comprise thermally generated graphene carbon nanoparticles.

57. The active composite particle of any one of claims 50 to 56, wherein the graphene carbon nanoparticles comprise exfoliated graphite nanoparticles.

58. The active composite particle of any one of claims 50 to 57, wherein the graphene carbon nanoparticles comprise carbon nanotubes.

59. The active composite particle of any one of claims 50 to 58, wherein the activated metal oxide particles comprise at least 1 weight percent, or at least 50 weight percent, or at least 70 weight percent of the active composite particle.

60. The active composite particle of any one of claims 50 to 59, wherein the activated metal oxide particles comprise at most 99 weight percent, or at most 95 weight percent, or at most 90 weight percent of the active composite particle.

61. The active composite particle of any one of claims 50 to 60, wherein the activated metal oxide particles comprise 1 to 99 weight percent, or 50 to 95 weight percent, or 70 to 90 weight percent of the active composite particle.

62. The active composite particle of any one of claims 50 to 61, wherein the graphene carbon nanoparticles account for at least 1 weight percent, or at least 5 weight percent, or at least 10 weight percent of the active composite particle.

63. The active composite particle of any one of claims 50 to 62, wherein the graphene carbon nanoparticles comprise at most 99 weight percent, or at most 50 weight percent, or at most 30 weight percent of the active composite particle.

64. The active composite particle of any one of claims 50 to 63, wherein the graphene carbon nanoparticles comprise 1 to 99 weight percent, or 5 to 50 weight percent, or 10 to 30 weight percent of the active composite particle.

65. The active composite particle of any one of claims 50 to 64, wherein the active composite particle further comprises a composite binder or dispersant.

66. The active composite particle of claim 65, wherein the composite binder or dispersant comprises polyacrylic acid neutralized with potassium hydroxide, or polyvinyl pyrrolidone.

67. The active composite particle of claim 65 or 66, wherein the composite binder comprises at most 10 weight percent, or at most 5 weight percent, or at most 2 weight percent, and / or at least 0.01 weight percent, or at least 0.1 weight percent of the active composite particle.

68. The active composite particle of any one of claims 50 to 67, wherein the active composite particle has an average particle size of at least 100 nanometers, or at least 1 micrometer, or at least 2 micrometers.

69. The active composite particle of any one of claims 50 to 68, wherein the active composite particle has an average particle size of at most 100 microns, or at most 20 microns, or at most 10 microns.

70. The active composite particle of any one of claims 50 to 69, wherein the active composite particle has an average particle size of 100 nanometers to 100 microns, or 1 to 20 microns, or 2 to 10 microns.

71. The active composite particle of any one of claims 50 to 70, wherein the active composite particle is spray dried.

72. A method for preparing active composite particles for supercapacitor electrode coatings, the method comprising: spray drying an aqueous solution comprising activated metal oxide particles and carbonaceous support particles; as well as The active composite particles comprising the activated metal oxide particles and the carbon-containing support particles are recovered.

73. A supercapacitor electrode comprising: Current collector substrate; as well as An electrode coating, the electrode coating comprising: Active composite particles comprising activated metal oxide particles and carbonaceous support particles; and Conductive carbonaceous particles.

74. The supercapacitor electrode of claim 73, wherein the supercapacitor electrode comprises a cathode.

75. The ultracapacitor electrode of claim 74, wherein the cathode is pretreated.

76. The supercapacitor electrode of claim 75, wherein the pretreated cathode comprises a surface layer comprising conductive carbon particles.

77. The supercapacitor electrode of claim 75 or 76, wherein the surface layer further comprises a binder.

78. The supercapacitor electrode of claim 77, wherein the binder comprises poly(vinylidene fluoride) and an acrylic acid copolymer cross-linked with melamine.

79. The supercapacitor electrode of any one of claims 73 to 78, wherein the current collector substrate comprises nickel, stainless steel, 316 stainless steel, 304 stainless steel, aluminum, copper, titanium, zirconium, graphite foil, carbon paper, or a combination thereof.

80. A supercapacitor comprising a supercapacitor electrode according to any one of claims 73 to 79, wherein the supercapacitor has a capacitance of at least 100 F / g, or at least 140 F / g, or at least 150 F / g.

81. A supercapacitor comprising a supercapacitor electrode according to any one of claims 73 to 79, wherein the supercapacitor has a capacitance of 100 to 300 F / g, or 140 to 250 F / g, or 150 to 200 F / g.

82. The ultracapacitor of any one of claims 80 and 81, wherein the capacitance is measured at a current density of 1 to 10 A / g.

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