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WO2013085498A1 - Pâtes à base de nanotubes de carbone - Google Patents

Pâtes à base de nanotubes de carbone Download PDF

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Publication number
WO2013085498A1
WO2013085498A1 PCT/US2011/063614 US2011063614W WO2013085498A1 WO 2013085498 A1 WO2013085498 A1 WO 2013085498A1 US 2011063614 W US2011063614 W US 2011063614W WO 2013085498 A1 WO2013085498 A1 WO 2013085498A1
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Prior art keywords
paste composition
carbon nanotube
poly
agglomerates
paste
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PCT/US2011/063614
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Inventor
Caihong Xing
Jianfeng Wang
Zhaojie Wei
Jun Ma
Ching-Jung Tsai
Qi Li
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Cnano Technology Ltd
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Cnano Technology Ltd
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Priority to PCT/US2011/063614 priority Critical patent/WO2013085498A1/fr
Publication of WO2013085498A1 publication Critical patent/WO2013085498A1/fr
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/24—Conductive material dispersed in non-conductive organic material the conductive material comprising carbon-silicon compounds, carbon or silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present disclosure relates to carbon nanotube-based pastes and methods of making such. Moreover, this paste may be applied as an electro-conductive additive in battery, capacitor, and other electronic devices.
  • Carbon nanotubes have many unique properties stemming from small sizes, cylindrical graphitic structure, and high aspect ratios.
  • a single-walled carbon nanotube (SWCNT) consists of a single graphite sheet wrapped around to form a cylindrical tube.
  • a multiwall carbon nanotube (MWCNT) includes a set of concentrically single layered nanotube placed along the fiber axis with interstitial distance of 0.34 nanometer.
  • Carbon nanotubes have extremely high tensile strength (-150 GPa), high modulus ( ⁇ 1 TPa), good chemical and environmental stability, and high thermal and electrical conductivity.
  • Carbon nanotubes have found many applications, including the preparation of conductive, electromagnetic and microwave absorbing and high-strength composites, fibers, sensors, field emission displays, inks, energy storage and energy conversion devices, radiation sources and nanometer-sized semiconductor devices, probes, and interconnects, etc.
  • polymers such as poly(vinylpyrrolidone) (PVP), poly(styrene sulfonate) (PSS), poly(pheny!acetylene) (PAA), poly(meta- phenylenevinylene) (PmPV), polypyrrole (PPy), poly(p-phenylene benzobisoxazole) (PBO) and natural polymers have been used to wrap carbon nanotubes and render them soluble in water or organic solvents.
  • SWCNTs single-walled carbon nanotubes
  • SDS sodium dodecyl sulfate
  • PVP polyvinylpyrrolidone
  • electro-conductive pastes or inks are comprised primarily of polymeric binders which contain or have mixed in a lesser amount of electro-conductive filler such as finely divided particles of metal such as silver, gold, copper, nickel, palladium or platinum and/or carbonaceous materials like carbon black or graphite, and a liquid vehicle.
  • a polymeric binder may attach the conductive filler to a substrate and/or hold the electro-conductive filler in a conductive pattern which serves as a conductive circuit.
  • the liquid vehicle includes solvents (e.g., liquids which dissolve the solid components) as well as non-solvents (e.g., liquids which do not dissolve the solid components).
  • the liquid vehicle serves as a carrier to help apply or deposit the polymeric binder and electro-conductive filler onto certain substrates.
  • An electro- conductive paste with carbon nanotubes dispersed within is a versatile material wherein carbon nanotubes form low resistance conductive networks.
  • an electro-conductive paste is in a liquid form; for example, a polymeric binder is a liquid at room temperature and a electro-conductive filler is dispersed therein.
  • Such electro-conductive pastes are described in U.S.5,098,771 to Friend entitled "Conductive Coatings and Inks"; incorporated herein in its entirety by reference. Friend describes a composite suitable for application to a surface comprising polymeric binder and between about 30 and 0.5 percent carbon nanotubes.
  • the coatings made by the conductive inks of Friend have bulk resistivity between 10 " 2 and 106 ohm-cm, and preferably between 10 " 1 and 10 4 ohm -cm.
  • Binder choices include polyethylene, polypropylene, polyamide, polyurethane, polyvinyl chloride, polyvinyl fluoride and thermoplastic polyester resins.
  • Dispersing carbon nanotubes can also be assisted with a surfactant as described by Sakakibara and co-workers in US Patent Application No.2007/0224106, now U.S.7,682,590; both incorporated herein in their entirety by reference; Sakakibara discloses single-walled carbon nanotubes are dispersed in polyvinylpyrrolidone dissolved in n-methylpyrrolidone with the presence of polyoxyethylene surfactant.
  • PVP and PVDF may undergo strong interaction as shown by N. Chen in "Surface phase morphology and composition of the casting films of PVDF-PVP blend", Polymer, 43, 1429 (2002).
  • the addition of PVP altered the crystallization of PVDF and hence modified its mechanical and adhesion properties.
  • the decreased of PVDF or combined PVP-PVDF can further improve the battery performance by allowing more addition of cathode material, so that improve the total capacity.
  • the present technology provides an electro-conductive paste, in one embodiment, comprising multi-wall carbon nanotubes, polyvinylpyrrolidone and a solvent.
  • multi-wall carbon nanotubes provide a means to create superior electro-conductive network in liquid form.
  • multi-wall carbon nanotubes provide a convenient means to pattern carbon nanotubes on a substrate or within the interstitial space of particulates when the properties of nanotubes are to be exploited.
  • the present technology relates to electro-conductive pastes that contain multi- wall carbon nanotubes.
  • the electro-conductive paste comprises dispersed carbon nanotubes and a liquid vehicle in which the size of solid particulates or agglomerates is less than 10 micrometers in at least one dimension.
  • electro-conductive pastes may further comprise a polymeric dispersant.
  • the polymeric dispersant is present in an amount less than that of carbon nanotubes by weight.
  • One exemplary dispersant is polyvinylpyrrolidone; polyvinylpyrrolidone provides sufficient bonding between CNT's and a liquid vehicle to stabilize the dispersed nanotubes; no additional binder is required, in some embodiments.
  • the present technology also addresses a method of making concentrate pastes, which may serve as a "masterbatch" comprising more nanotube filler content than required for some applications.
  • a master batch is diluted with additional liquid or solid, a concentration of nanotubes therein can be adjusted down to a desired level for final applications; for example, use as electro-conductive additive in lithium ion battery electrodes.
  • Figure 1 illustrates a process of making carbon nanotube-based electro-conductive paste.
  • Figure 2 shows the relationship of paste viscosity as a function of the duration of milling as described in Example 1.
  • Figure 3 illustrates the relationship of paste viscosity as a function of the ratio of carbon nanotube versus PVP as described in Example 2.
  • Figure 4 shows the electron micrograph of dispersed carbon nanotubes within a Lithium iron phosphate particulate network.
  • Figure 5 shows the comparison of charge/discharge cycles at various charge speed from carbon nanotube and carbon black-decorated Lithium ion coin battery.
  • Figure 6 shows spherical agglomerates of carbon nanotube made in a fluidized bed reactor.
  • Figures 6a, b and c of U.S. 2009/0286675 show spherical agglomerates of carbon nanotube made in a fluidized bed reactor with distinctive properties critical to the instant invention.
  • Figure 6a are carbon nanotube agglomerates with an average diameter of about 100 microns.
  • Figure 6b shows that the large spherical agglomerates are actually a composite agglomerate with hundreds of nano agglomerate in an adhesion formation.
  • Figure 6c shows the entanglement of interwoven carbon nanotubes within the nano-sized agglomerates.
  • Figure 6 of the instant invention is another view of agglomerates as required by the instant invention.
  • the carbon nanotubes are in the form of agglomerates; most of the agglomerates are near spherical in shape with diameters of less than 100 microns.
  • the carbon nanotube agglomerates are the roughly spherical particles with an average diameter of about 100 microns.
  • the density of the agglomerates is from 0.050 to 0.200 g/cm 3 .
  • the carbon nanotubes produced using a fluidized bed with the carbon nanotube agglomerates are highly crystalline, having a purity of greater than 96%. Forming nano-agglomerates is a critical step for growth of carbon nanotubes in a fluidized-bed reactor.
  • Nano-agglomerates are defined as agglomerates with a dimension of 1-1000 microns composed of nano-scale materials in an aggregated structure.
  • the catalyst agglomerates are not only effecting the catalytic growth but also impacting the microstructure and morphology of the final carbon nanotube agglomerates with diameters of 4-100 nm, and length of 0.5 to 1000 micron.
  • the aggregation strength of the composite agglomerates is not very high. For purposes herein, aggregation of small agglomerates is called a “simple agglomerate”, and re-aggregation of simple agglomerates together to form large aggregates is called “composite agglomerate" or "complex agglomerate”.
  • the average volume diameter of simple agglomerates is on the order of microns while that of composite agglomerate is on order of the tens of microns.
  • High-magnification scanning electron microscope shows that the agglomerates are rich in carbon nanotubes, similar to fluffy cotton. Formation of loose agglomerate structure is unique and unexpected, requiring specific conditions; not all nano- material processes form a loose agglomerate structure. Formation of loose agglomerate structure is unique to the cited prior art of the assignee.
  • the fluidized bed reaction is under a dense phase fluidization and there is no deposit of amorphous carbons on the nanotubes.
  • Carbon nanotubes and carbon nanotube agglomerates of various structures and morphologies can be prepared using the methods of the cited inventions.
  • starting with spherical agglomerates is critical to attaining a paste composite composition with the desired properties.
  • agglomerate refers to microscopic particulate structures of carbon nanotubes; for example, an agglomerate is typically an entangled mass of nanotubes; a mass having dimensions between about 0.5 ⁇ to about 5 mm as made.
  • carbon nanotube means a hollow carbon structure having a diameter from about 4 to about 100 nm; for purposes herein "carbon nanotube” means multi-walled nanotubes exhibiting little to no chirality.
  • multi-wall carbon nanotube refers to carbon nanotubes wherein graphene layers form more than one concentric cylinder placed along the fiber axis.
  • carbon nanotube-based paste refers to an electro-conductive composite in which an electro-conductive filler is combined with multi-wall carbon nanotubes.
  • composite means a material comprising at least one polymer and at least one multi-wall carbon nanotube and/or agglomerate.
  • a composite may be a suspension or paste or other mixture comprising nanotubes and one or more other materials; a suspension is also mixture comprising nanotubes and one or more other materials, typically a dispersant(s) and liquid vehicle(s).
  • carbon nanotubes often form entanglements, also known as agglomerates.
  • U.S. 7,563,427 hereby incorporated herein in its entirety by reference, describes such agglomerates comprising a plurality of transition metal nanoparticles and solid supports, wherein a plurality of metal nanoparticles and supports are combined to form a plurality of catalyst nano-agglomerates; a plurality of multi-walled carbon nanotubes deposited on a plurality of catalyst nano-agglomerates.
  • the agglomerates have sizes from about 0.5 to 10,000 micrometers, wherein carbon nanotubes are in the form of multiwall nanotubes having diameters of about 4 to 100 nm.
  • the size of as-made agglomerates can be reduced by various means.
  • a representative characteristic of these agglomerates is their tap density; the tap density of as-made agglomerates can vary from 0.02 to 0.20 g/cm 3 depending upon catalyst, growth condition, process design, and other factors. Rigid agglomerates tend to have high tap densities, while fluffy ones and single-walled nanotubes have low tap densities.
  • Dispersant serves as an aid for dispersing carbon nanotubes in a solvent. It can be a polar polymeric compound, a surfactant, or high viscosity liquid such as mineral oil or wax.
  • Dispersants used in the current invention include poly(vinylpyrrolidone) (PVP), poly(styrene sulfonate) (PSS), poly(phenylacetylene) (PAA), poly(meta-phenylenevinylene) (PmPV), polypyrrole (PPy), poly(p-phenylene benzobisoxazole) (PBO), natural polymers, amphiphilic materials in aqueous solutions, anionic aliphatic surfactant, sodium dodecyl sulfate (SDS), cyclic lipopeptide biosurfactant, surfactin, water-soluble polymers, poly(vinyl alcohol), PVA, sodium dodecyl sulfate (SDS), polyoxyethylene surfactant, poly(vinyl
  • Polyvinylpyrrolidone binds polar molecules extremely well.
  • PVP has different properties when used as a binder or as a dispersing agent such as a thickener; as used herein a thickener may be a viscous polymer, a binder or dispersant.
  • molecular weights for dispersants and/or binders range between about 9,000 and 1,800,000 Daltons; in some embodiments, between about 50,000 to 1,400,000 Daltons are preferred; in some embodiments between about 55,000 to 80,000 Daltons are preferred.
  • a liquid vehicle may serve as a carrier for carbon nanotubes.
  • Liquid vehicles may be a solvent or a non-solvent, depending upon whether or not a vehicle dissolves solids which are mixed therein.
  • the volatility of a liquid vehicle should not be so high that it vaporizes readily at relatively low temperatures and pressures such as room temperature and pressure, for instance, 25°C and 1 atm. The volatility, however, should not be so low that a solvent does not vaporize somewhat during paste preparation.
  • a liquid vehicle is used to dissolve polymeric dispersant(s) and entrain carbon nanotubes in order to render a composition that is easily applied to a substrate.
  • liquid vehicles include, but are not limited to, water, alcohols, ethers, aromatic hydrocarbons, esters, ketones, n-methyl pyrrolidone and mixtures thereof.
  • water is used as a solvent to dissolve polymers and form liquid vehicles.
  • these aqueous systems can replace solvent based inks while maintaining designated thixotropic properties, as disclosed in U.S.4,427,820, incorporated herein in its entirety by reference.
  • one means of reducing the size of large agglomerates to acceptable size agglomerates is to apply a shear force to an agglomerate; a shear force is one technique to aid with dispersion.
  • Means to apply a shear force include, but are not limited to, milling, sand milling, sonication, grinding, cavitation, or others known to one knowledgeable in the art.
  • carbon nanotubes are first reduced in size by using a jet-miller.
  • the tap density can decrease after dispersion, optionally by milling, to around 0.06 g/cm 3 in some embodiments, or 0.04 g/cm 3 in some embodiments, or 0.02 g/cm 3 in some embodiments.
  • a colloid mill or sand mill or other technique is then used to provide sufficient shear force to further break up nanotube agglomerates, as required by an application.
  • nanotube agglomerates is decreased as nanotubes are freed from entanglements, entering a liquid vehicle as individualized nanotubes or agglomerates of size less than 10 micrometers, preferably less than 5 micrometers and more preferably less than 1 micrometers in one dimension.
  • the fineness of remaining agglomerates can be measured using a Hegman gauge as indicated by "Hegman scale”.
  • Hegman Fineness-of-Grind Gage is a flat steel block in the surface of which are two flat-bottomed grooves varying uniformly in depth from a maximum at one end of the block to zero near the other end.
  • Groove depth is graduated on the block according to one or more scales used for measuring particle size.
  • the degree of dispersion is indicated in microns or "Hegman”.
  • the Hegman scale or National Standard scale may be abbreviated "NS"; the scale ranges from 0 to 8 with numbers increasing as the particle size decreases.
  • a Hegman reading of 7 or greater is indicative of a MWNT agglomerate size of less than 10 microns in one dimension.
  • a MWNT agglomerate size is less than 10 microns; optionally less than 5 microns; optionally less than one micron.
  • Dispersed nanotubes are known in the art to increase the viscosity of a medium therein. Thus viscosity measurement can also serve as a barometer of possible dispersion limit as the paste viscosity reaches a maximum.
  • a paste viscosity 5,000 cps or greater is preferred depending upon the application.
  • carbon nanotube paste can be treated via centrifugation to remove excessive liquid vehicle while preventing nanotubes re-agglomerating into large particles.
  • Alternative methods include but are not limited to vacuum filtration, pressurized filtration, or combinations thereof.
  • the extracted solvent can be recycled and reused as liquid vehicle.
  • the nanotube content in the condensed paste in one embodiment is 1-20%, in one embodiment 2-15%, and in one embodiment 5-10% by weight.
  • an electro-conductive paste comprising a dispersant, carbon nanotubes and liquid vehicle
  • a solution is first formed by blending a dispersant with a liquid vehicle until the dispersant is uniformly mixed in the vehicle.
  • Any conventional means of mixing or agitation known in the art can be used, for example, a blender, mixer, stir bar, or other means.
  • as-made carbon nanotube agglomerates are reduced in size with a jet miller or other means of size reduction as previously listed. Ground nanotubes of the desired concentration are then added and/or mixed with the solution. The carbon nanotubes can optionally be added via another liquid carrier. On the other hand, if no polymeric binder is used to form the electro-conductive paste, then carbon nanotubes can be added initially to a liquid vehicle and mixed therein.
  • carbon nanotubes are dispersed uniformly in a solution using one or more uniform dispersion means; exemplary dispersion means are jet mill, sonicator, ultrasonics, colloid-mill, ball-mill, bead-mill, sand-mill, and roll-mill.
  • exemplary dispersion means are jet mill, sonicator, ultrasonics, colloid-mill, ball-mill, bead-mill, sand-mill, and roll-mill.
  • a colloid mill can be used at a high enough power setting to ensure uniform dispersion. The milling generates shear forces that make carbon nanotube particles more uniform and smaller resulting in increased homogeneity. Milling may continue until gel-like slurry of uniformly dispersed nanotubes is obtained.
  • wet milling can be performed (i) in a mixture with the liquid vehicle with, or without, the polymer binder, or (ii) at a dilute level in the liquid vehicle with subsequent concentration and drying.
  • Dispersion is not very effective at carbon nanotube concentrations higher than 5% by weight because high viscosity prevents convection and mixing; lower concentrations of nanotubes result in greater dispersion.
  • a paste is condensed by removing excess liquid with, for example, a centrifuge; centrifugation causes dispersed material to become more concentrated.
  • a final dispersed state is affected by a final concentration, additional milling processes and dispersant and/or liquid content.
  • a liquid vehicle can be recycled or reused to make additional paste.
  • One method to formulate a carbon nanotube-based conductive paste comprises the steps: selecting an as-grown, multi-walled carbon nanotube; optionally, reducing the size of the as-grown, multi-walled carbon nanotube agglomerates by dry milling; mixing with a dispersant with a liquid vehicle; optionally, reducing the size of the as-grown, multi-walled carbon nanotube agglomerates by wet milling ; mixing the size reduced carbon nanotubes with the mixed dispersant and liquid vehicle followed, optionally, by high shear milling particles and/or agglomerates remaining in the said paste to achieve a Hegman scale of 7 or higher; and, optionally, removing a predetermined portion of the liquid vehicle by centrifuge or other drying means to achieve a viscosity of greater than 5000 cps.
  • FIG. 1 illustrates an exemplary process of making carbon nanotube-based conductive paste.
  • a starting material “1” is as-made carbon nanotube agglomerates.
  • the ground nanotubes are mixed with dispersant and liquid vehicle in a vessel "3".
  • the mixture then passes through a colloid mill “4" for a predetermined amount of time before becoming a conductive paste "5". Further condensation in a centrifuge "6” forms preferred formulations with concentrated nanotube content "7". Excessive amounts of solvent and dispersant are sent back to "3" for reuse.
  • Lithium-ion batteries are a type of rechargeable battery in which lithium ions move from the negative electrode (anode) to the positive electrode (cathode) during discharge, and from the cathode to the anode during charge.
  • the three primary functional components of a lithium-ion battery are the anode, cathode, and electrolyte, for which a variety of materials may be used.
  • the most popular material for the anode is graphite.
  • the cathode is generally one of three materials: a layered oxide (such as lithium cobalt oxide), one based on a polyanion (such as lithium iron phosphate), or a spinel (such as lithium manganese oxide), although materials such as TiS 2 (titanium disulfide) originally were also used.
  • a layered oxide such as lithium cobalt oxide
  • a polyanion such as lithium iron phosphate
  • a spinel such as lithium manganese oxide
  • TiS 2 titanium disulfide
  • Li-ion batteries also contain polymeric binders, conductive additives, separator, and current collectors. Carbon black such as Super-PTM made by Timcal Corporation is usually used as conductive additives.
  • the instant invention discloses the use of carbon nanotube-based conductive paste for both the cathode and the anode in a Lithium-ion battery. Once deposited inside the active materials, the carbon nanotubes create conductive networks within particulates, so as to enhance overall conductivity and reduce battery internal resistance. A modified battery can have improved capacity and cycle life owing to the conductive network built by carbon nanotubes.
  • Example 1 Dispersion of carbon nanotubes in n-methylpyrrolidone
  • Viscosity was taken at 25°C using Brookfield viscometer for each sample and recorded in Figure 2. Hegman scale reading was taken simultaneously and illustrated. Maximum dispersion was observed after milling for 90 minutes. The fineness of this pastes reached better than 10 micrometer after 60 minutes of milling.
  • a CNT paste comprising 2%CNT and 0.4% PVP k30 was selected to make a Lithium-ion coin battery.
  • LiFePC manufactured by Phostech/Sud Chemie was used as cathode material and Lithium foil was used as anode.
  • the cathode materials containing LiFeP0 4 , CNT, PVP, and PVDF were prepared by mixing appropriate amounts of LiFeP0 4 , CNT paste and PVDF together with n-methylpyrrolidone in a Warren blender. Coating of such paste was made on an Al foil using a doctor blade followed by drying and compression.
  • Figure 4 showed a conductive network formed by CNT coating on LiFeP0 4 observed under scanning electron microscope (SEM)
  • a coin battery was assembled using cathode composition defined in Example 5 and Lithium foil as anode.
  • the capacity of cycle life was evaluated at 25°C.
  • the charge and discharge cycles under different speed were illustrated in Figure 5.
  • the CNT-modified battery exhibited better performance in term of charge capacity and stability.
  • Example 1 Samples made in Example 1 were subject to centrifuge to extract excessive amount of solvent and the CNT content can reach 5, 10 and 15%. The condensed can be re- diluted with additional n-methylpyrrolidone under high-speed agitation. Battery with the same CNT loading made from such paste was made using procedure described in Example 3, and evaluated following the same procedure as shown in Example 4. There was no significant difference in battery performance among various batteries.
  • a highly conductive CNT paste can be prepared using very small amounts of PVP and no other binders. Using such paste in a Lithium ion battery can greatly improve the battery performance.
  • Exemplary lithium ion battery materials comprise lithium based compounds and or mixtures comprising lithium and one or more elements chosen from a list consisting of oxygen, phosphorous, sulphur, nitrogen, nickel, cobalt, manganese, vanadium, silicon, carbon, aluminum, niobium and zirconium and iron.
  • Typical cathode materials include lithium-metal oxides, such as LiCo0 2 , LiMn 2 0 , and Li(Ni x Mn y Co z )0 2 ], vanadium oxides, olivines, such as LiFeP0 4 , and rechargeable lithium oxides.
  • Layered oxides containing cobalt and nickel are materials for lithium-ion batteries also.
  • Exemplary anode materials are lithium, carbon, graphite, lithium-alloying materials, intermetallics, and silicon and silicon based compounds such as silicon dioxide. Carbonaceous anodes comprising silicon and lithium are utilized anodic materials also. Methods of coating battery materials in combination with a carbon nanotube agglomerate onto anodic or cathodic backing plates such as aluminum or copper, for example, are disclosed as an alternative embodiment of the instant invention.
  • a paste composition comprises carbon nanotube agglomerates; a dispersant; and a liquid vehicle; wherein the carbon nanotube agglomerates are dispersed as defined by a Hegman scale reading of 7 or more; optionally, the carbon nanotubes are multiwall carbon nanotubes; optionally carbon nanotubes are in a spherical agglomerates; optionally, a paste composition comprises a dispersant selected from a group consisting of poly(vinylpyrrolidone) (PVP), poly(styrene sulfonate) (PSS), poly(phenylacetylene) (PAA), poly(meta-phenylenevinylene) (PmPV), polypyrrole (PPy), poly(p-phenylene benzobisoxazole) (PBO), natural polymers, amphiphilic materials in aqueous solutions, anionic aliphatic surfactant, sodium dodecyl sulfate (SDS),
  • PVP poly(vin
  • a method for making a paste composition comprises the steps: selecting carbon nanotube agglomerates; adding the carbon nanotubes agglomerates to a liquid vehicle to form a suspension; dispersing the carbon nanotubes agglomerates in the suspension; reducing the size of the carbon nanotube agglomerates to a Hegman scale of 7 or less; and removing a portion of the liquid vehicle from the suspension to form a concentrated paste composition such that the paste composition has carbon nanotubes present in the range of about 1 to 15% by weight, a bulk electrical resistivity of about 10 "1 ⁇ -cm or less and a viscosity greater than 5,000 cps; optionally, a method further comprises the step of mixing a dispersant with the liquid vehicle before adding the carbon nanotube agglomerates; optionally, a method wherein the dispersing step is performed by a means for dispersing chosen from a group consisting of jet mill, ultra-sonicator, ultrasonics, colloid-mill,
  • a paste composition consists of multi-walled carbon nanotubes of diameter greater than 4nm; a dispersant chosen from a group consisting of poly(vinylpyrrolidone) (PVP), poIy(styrene sulfonate) (PSS), poly(phenylacetylene) (PAA), poly(meta-phenylenevinylene) (PmPV), polypyrrole (PPy), poly(p-phenylene benzobisoxazole) (PBO), natural polymers, amphiphilic materials in aqueous solutions, anionic aliphatic surfactant, sodium dodecyl sulfate (SDS), cyclic lipopeptide biosurfactant, surfactin, water- soluble polymers, carboxyl methyl cellulose, hydroxyl ethyl cellulose, poly(vinyl alcohol), PVA, sodium dodecyl sulfate, SDS, polyoxyethylene surfactant, poly(
  • a method of preparing an battery electrode coating using a paste composition as disclosed herein comprises the steps: mixing the paste composition with lithium ion battery materials; coating the paste onto a metallic film to form an electrode for a lithium ion battery and removing excess or at least a portion of the liquid from the coating; optionally, a method further comprises the step of mixing a polymeric binder with a liquid vehicle before mixing the paste composition with lithium ion battery materials; optionally, a method uses a polymeric binder chosen from a group consisting of polyethylene, polypropylene, polyamide, polyurethane, polyvinyl chloride, polyvinylidene fluoride, thermoplastic polyester resins, and mixtures thereof and is less than about 5% by weight of the paste composition; optionally, a method utilizes spherical carbon nanotube agglomerates fabricated in a fluidized bed reactor as described in Assignee's inventions U.S.
  • a paste composition as disclosed herein utilizes spherical carbon nanotube agglomerates fabricated in a fluidized bed reactor as described in Assignee's inventions U.S. 7,563,427, and U.S. Applications 2009/0208708, 2009/0286675, and U.S. 12/516,166.
  • this writing sets forth at least the following: carbon-nanotube based pastes and methods for making and using the same. Carbon nanotubes are dispersed via milling; resultant paste has Hegman scale of greater than 7.
  • the pastes can be used as electro- conductivity enhancement in electronic devices such as batteries, capacitors, electrodes or other devices needing high conductivity paste.
  • a paste composition comprising:
  • Concept 3 The paste composition of Concept 1, wherein the dispersant is selected from a group consisting of polyvinylpyrrolidone) (PVP), poly(styrene sulfonate) (PSS), poly(phenylacetyIene) (PAA), poly(meta-phenylenevinylene) (PmPV), polypyrrole (PPy), poly(p-phenylene benzobisoxazole) (PBO), natural polymers, amphiphilic materials in aqueous solutions, anionic aliphatic surfactant, sodium dodecyl sulfate (SDS), cyclic lipopeptide biosurfactant, surfactin, water-soluble polymers, carboxyl methyl cellulose, hydroxyl ethyl cellulose, poly(vinyl alcohol), PVA, sodium dodecyl sulfate, SDS, polyoxyethylene surfactant, poly(vinylidene fluoride), PVdF, carboxyl methyl cellulose (C
  • a method for making a paste composition comprising the steps:
  • removing a portion of the liquid vehicle from the suspension to form a concentrated paste composition such that the paste composition has carbon nanotubes present in the range of about 1 to 15% by weight, a bulk electrical resistivity of about 10-1 ⁇ -cm or less and a viscosity greater than 5,000 cps.
  • Concept 17 The method of Concept 15, further comprising the step of mixing a dispersant with the liquid vehicle before adding the carbon nanotube agglomerates.
  • Concept 18 The method of Concept 15, wherein the dispersing step is performed by a means for dispersing.
  • a paste composition consisting of;
  • a dispersant chosen from a group consisting of poly(vinylpyrrolidone) (PVP), poly(styrene sulfonate) (PSS), poly(phenylacetylene) (PAA), poly(meta- phenylenevinylene) (PmPV), polypyrrole (PPy), poly(p-phenylene benzobisoxazole) (PBO), natural polymers, amphiphilic materials in aqueous solutions, anionic aliphatic surfactant, sodium dodecyl sulfate (SDS), cyclic lipopeptide biosurfactant, surfactin, water-soluble polymers, carboxyl methyl cellulose, hydroxyl ethyl cellulose, poly(vinyl alcohol), PVA, sodium dodecyl sulfate, SDS, polyoxyethylene surfactant, poly(vinylidene fluoride), PVdF, carboxyl methyl cellulose (CMC), hydroxyl ethyl
  • a liquid vehicle chosen from a group consisting of water, alcohols, ethers, aromatic hydrocarbons, esters, ketones, n-methyl pyrrolidone and mixtures thereof such that the paste composition has carbon nanotubes present in the range of about 1 to 15% by weight, a bulk electrical resistivity of about 10-1 ⁇ -cm or less and a viscosity greater than 5,000 cps.
  • the paste composition of Concept 19 further consisting of lithium ion battery electrode materials chosen from a group consisting of lithium, oxygen, phosphorous, sulphur, nitrogen, nickel, cobalt, manganese, vanadium, silicon, carbon, aluminum, niobium and zirconium and iron wherein the paste composition is present in a range from about 2% to about 50% by weight and the viscosity is greater than about 5,000 cps.
  • Concept 25 The method of Concept 23 wherein the polymeric binder is chosen from a group consisting of polyethylene, polypropylene, polyamide, polyurethane, polyvinyl chloride, polyvinylidene fluoride, thermoplastic polyester resins, and mixtures thereof and is less than about 5% by weight of the paste composition.
  • the polymeric binder is chosen from a group consisting of polyethylene, polypropylene, polyamide, polyurethane, polyvinyl chloride, polyvinylidene fluoride, thermoplastic polyester resins, and mixtures thereof and is less than about 5% by weight of the paste composition.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Dispersion Chemistry (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Carbon And Carbon Compounds (AREA)

Abstract

La présente invention a trait à des pâtes à base de nanotubes de carbone ainsi qu'à leurs procédés de fabrication et d'utilisation. Les nanotubes de carbone sont décomposés par le biais d'un broyage, la pâte ainsi obtenue possède une valeur supérieure à 7 sur l'échelle Hegman. Ces pâtes peuvent servir à accroître l'électro-conductivité dans des dispositifs électroniques, tels que des batteries, des condensateurs, des électrodes ou d'autres dispositifs ayant besoin d'une pâte à haute conductivité.
PCT/US2011/063614 2011-12-06 2011-12-06 Pâtes à base de nanotubes de carbone Ceased WO2013085498A1 (fr)

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JP2015195143A (ja) * 2014-03-31 2015-11-05 戸田工業株式会社 カーボンナノチューブ分散液および非水電解質二次電池
JP2018503946A (ja) * 2015-01-13 2018-02-08 エルジー・ケム・リミテッド リチウム二次電池の正極形成用組成物の製造方法、及びこれを利用して製造した正極及びリチウム二次電池
JP2018127397A (ja) * 2018-02-19 2018-08-16 戸田工業株式会社 カーボンナノチューブ分散液および非水電解質二次電池
CN109935888A (zh) * 2017-12-19 2019-06-25 成都亦道科技合伙企业（有限合伙） 集流体结构、锂电池电芯及其锂电池
CN112794308A (zh) * 2020-12-31 2021-05-14 西安理工大学 一种分列式层级结构碳微球的制备方法
CN112909250A (zh) * 2019-11-19 2021-06-04 中能中科（天津）新能源科技有限公司 碳材料微球、锂碳粉及其制备方法和应用
CN113036146A (zh) * 2021-03-10 2021-06-25 哈尔滨万鑫石墨谷科技有限公司 一种碳纳米管导电浆料及其制备方法和应用
CN113680463A (zh) * 2021-07-02 2021-11-23 中国科学院重庆绿色智能技术研究院 一种提高二元光学吸收剂复合效率的过程控制剂
CN113826239A (zh) * 2019-03-22 2021-12-21 卡博特公司 用于电池应用的阳极电极组合物和含水分散体
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CN114324335A (zh) * 2021-12-30 2022-04-12 沈阳汇晶纳米科技有限公司 一种表征锂电池导电浆料分散状态的测试方法
CN114824264A (zh) * 2021-01-27 2022-07-29 通用汽车环球科技运作有限责任公司 电池组电极的碳基导电填料前体分散体及制造和使用方法
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CN116435513A (zh) * 2023-04-11 2023-07-14 深圳市金百纳纳米科技有限公司 一种水性单壁碳纳米管导电浆料及其制备方法和应用
CN116803901A (zh) * 2022-03-17 2023-09-26 曲靖华金雨林科技有限责任公司 一种制备碳纳米管溶液的方法
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WO2025024382A3 (fr) * 2023-07-25 2025-04-03 Birla Carbon U.S.A., Inc. Procédé de roulage des bords et de séchage de compositions à base de nanotubes de carbone

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CN103886932A (zh) * 2014-03-25 2014-06-25 深圳市纳米港有限公司 碳纳米管导电浆料及其制备方法和用途
JP2015195143A (ja) * 2014-03-31 2015-11-05 戸田工業株式会社 カーボンナノチューブ分散液および非水電解質二次電池
JP2018503946A (ja) * 2015-01-13 2018-02-08 エルジー・ケム・リミテッド リチウム二次電池の正極形成用組成物の製造方法、及びこれを利用して製造した正極及びリチウム二次電池
US10290859B2 (en) 2015-01-13 2019-05-14 Lg Chem, Ltd. Method of preparing composition for forming positive electrode of lithium secondary battery, and positive electrode and lithium secondary battery manufactured by using the composition
CN109935888A (zh) * 2017-12-19 2019-06-25 成都亦道科技合伙企业（有限合伙） 集流体结构、锂电池电芯及其锂电池
JP2018127397A (ja) * 2018-02-19 2018-08-16 戸田工業株式会社 カーボンナノチューブ分散液および非水電解質二次電池
CN113826239B (zh) * 2019-03-22 2024-01-23 卡博特公司 用于电池应用的阳极电极组合物和含水分散体
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