1225 results about "Natural graphite" patented technology

Processes for synthesizing graphene films. Graphene films may be synthesized by heating a metal or a dielectric on a substrate to a temperature between 400° C. and 1,400° C. The metal or dielectric is exposed to an organic compound thereby growing graphene from the organic compound on the metal or dielectric. The metal or dielectric is later cooled to room temperature. As a result of the above process, standalone graphene films may be synthesized with properties equivalent to exfoliated graphene from natural graphite that is scalable to size far greater than that available on silicon carbide, single crystal silicon substrates or from natural graphite.

This invention provides a graphite or graphite-carbon particulate for use as a lithium secondary battery anode material having a high-rate capability. The particulate is formed of a core carbon or graphite particle and a plurality of satellite carbon or graphite particles that are each separately bonded to the core particle wherein the core particle is spherical in shape, slightly elongate in shape with a major axis-to-minor axis ratio less than 2, or fibril in shape, and wherein the satellite particles are disc-, platelet-, or flake-like particles each containing a graphite crystallite with a crystallographic c-axis dimension Lc and a lateral dimension. Preferably, Lc is less than 100 nm and the flake/platelet lateral dimension is less than 1 μm. The core particle may be selected from natural graphite, artificial graphite, spherical graphite, graphitic coke, meso-carbon micro-bead, soft carbon, hard carbon, graphitic fibril, carbon nano-fiber, carbon fiber, or graphite fiber. Preferably, the flat-shaped particles are randomly oriented with respect to one another.

The invention discloses a silicon-carbon negative electrode material of a lithium ion battery and a preparation method thereof, and solves the technological problem of improving the charge and discharge cycling stability of the electrode material. The silicon-carbon negative electrode material is prepared by mixing a silicon-carbon composite material and a natural graphite material, wherein the weight of the silicon-carbon composite material is 7-20% and the silicon-carbon composite material is prepared by depositing carbon nanotube and/or carbon nanofiber on the surface of nanometer silica fume and/or embedding into the nanometer silica fume to form core, the surface of which is covered with 3-15wt% of a carbon layer. The preparation method provided by the invention comprises steps of: precursor silicon powder preparation; chemical vapor deposition; liquid-coating roasting; crushing; and mixing. In comparison with the prior art, the reversible specific capacity of the silicon-carbon composite negative electrode material is greater than 500mAh/g; the coulombic efficiency for a first cycle is greater than 80%; the capacity conservation rate of cycling for 50 weeks is greater than 95%. The preparation method is simple, is easy to operate, requires low cost and is suitable for a high-volume negative electrode material of lithium ion batteries used for various portable devices.

The invention relates to a method for simply and innoxiously preparing single-layer graphene, belonging to the chemical field of inorganic field. The technical processes of the invention are as follows: adopting a fixed amount of natural graphite powder; oxidizing the natural graphite powder in a strong oxidizing condition to obtain the graphite oxide; dispersing the obtained graphite oxide in the de-ionized water; then ultrasonically processing for a certain period in an ultrasonic machine to peel the graphite oxide off into single-layer graphite oxide sheet; then dispersing the graphite oxide sheet in the dimethylsulfoxide solution; transferring the mixture solution to a reaction kettle and reacting for 10 to 16 hours in 150 to 200 degrees centigrade; after filtered, obtaining the mass colour product, that is, single-layer grapheme. The invention adopts nontoxic reducing agent, dimethylsulfoxide, so it is good for environment protection. The invention has simple technique, operation convenience, and low manufacturing cost.

The invention relates to an anode for lithium secondary battery comprising vapor grown carbon fiber uniformly dispersed without forming an agglomerate of 10 μm or larger in an anode active material using natural graphite or artificial graphite, which anode is excellent in long cycle life and large current characteristics. Composition used for production for the anode can be produced, for example, by mixing a thickening agent solution containing an anode active material, a thickening agent aqueous solution and styrene butadiene rubber as binder with a composition containing carbon fiber dispersed in a thickening agent with a predetermined viscosity or by mixing an anode active material with vapor grown carbon fiber in dry state and then adding polyvinylidene difluoride thereto.

There are provided modified and rounded graphite particles derived from scaly natural graphite particles by modification so as to bring their form close to a spherical form and satisfying all the following requirements (a) to (c): (a) that the degree of circularity should be not less than 0.86; (b) that, upon microscopic observation, the broken-out section should show a cabbage-like appearance with graphite slices taking various directions; and (c) that, upon X ray diffraction, the peak intensity ratio (Ih110/Ih002) between the 002 face (parallel to graphite layers) and 110 face (perpendicular to graphite layers), which serves as an index of the randomness of orientation, should be not less than 0.0050. They retain good qualities of the raw material scaly natural graphite particles and are additionally unique in structure and characteristics. A method of producing such modified particles is also provided. Further provided are secondary cells or batteries in which the modified particles showing good slurry characteristics are used as an electrode material and with which the decrease in discharge capacity is small even at high discharge current values.

The invention relates to a conductive heating material. The material comprises a substrate and a conductive heating layer evenly adhered to the substrate, wherein the conductive heating layer is made from a conductive heating coating material; the conductive heating coating material comprises a conductive heating base material and a bonding agent; the conductive heating base material is selected from natural graphite, artificial graphite and conductive carbon black; the bonding agent is selected from acrylic resin, epoxy resin, polyurethane resin, glutin, carboxymethyl cellulose, polyvinyl alcohol, and the like; and the substrate can adopt paper in a plurality of practical implementation modes. The conductive heating material can be used to make the conductive heating floor; the surface temperature of the floor can reach 15 to 70 DEG C within 5 minutes after the floor is energized with 220V voltage; moreover, the floor can maintain stable temperature for a long time. Therefore, the conductive heating floor can be used to replace the prior ground heating system and has low cost, reliable operation, energy saving, environmental protection and convenient maintenance and replacement.

Carbon powder having low temperature calcined carbon derived from pitch adhered to a portion of the surface of natural graphite powder is obtained by solids mixing of natural graphite powder and pitch powder as a carbon precursor followed by heat treatment at 900-1500° C. to carbonize the pitch. The amount of pitch powder is such that the ratio V2/V1 of the pore volume V2 of pores having a diameter of 50-200 nm to the pore volume V1 of pores having a diameter of 2-50 nm in a pore size distribution curve obtained by analysis of the nitrogen desorption isotherm of the resulting carbon powder by the BJH method is at least 1. This carbon powder can be used as a negative electrode material for a nonaqueous secondary battery able to operate at low temperatures.

The invention may be practiced to make graphite composites. Preferred composites which may be made in accordance with the invention include conductive polymeric composites (thermally or electrically), paint composites, battery composites, capacitor composites, and pollution abatement catalyst support composites. One method of making the graphite aforementioned composites includes introducing an intercalant into at least one interstice of at least one flake of natural graphite. The method also includes introducing a fluid into the at least one interstices of the flake. Preferably, the fluid comprises at least one of a sub-critical fluid, near critical point fluid, or a supercritical fluid. Furthermore the method includes blending the flake with a polymer, thereby forming a graphite-polymeric composite.

The invention discloses a carbon contact strip of a pantograph and a manufacturing method thereof. The carbon contact strip is prepared from following raw materials, by weight, 28-43 parts of petroleum coke powder, 25-28 parts of asphalt coke powder, 10-12 parts of sprayed carbon black, 2-5 parts of sulfur, 3-5 parts of boron nitride, 5-8 parts of carbon fiber, 4-6 parts of natural graphite, 5-7 parts of artificial graphite, 1-3 parts of calcium chloride powder and 30-35 parts of modified asphalt. The carbon contact strip is high in mechanical strength, is good in self-lubricating performance and electric arc resistance and is wear-resistant. The carbon contact strip can be not only used in various locomotives in railway main lines with speed per hour being 120-250 km/h, but also used in motor train units and high-speed trains with speed per hour being higher than 250 km/h. The carbon contact strip is free of limit of environment and climate conditions.

The invention provides a high-rate charge-discharge lithium-ion battery and a preparation method thereof. The anode active material of the lithium-ion battery is lithium manganate; the cathode active material is selected from one or more of mesocarbon microbeads, artificial graphite or natural graphite coated by mesophase pitch; a conductive agent is selected from one or more of conductive graphite, conductive carbon black, nano Ag, nano SiO2 or nano Al2O3. The preparation method of the lithium-ion battery comprises the preparation of the anode plate, the parathion of the cathode plate and the assembly of the battery. The lithium-ion battery has the advantages of high-rate charge-discharge performance, long cycle life, high capacity, safe use, environmental protection, low cost and the like. The preparation method has the advantage of simple and easy process operation, and is applicable to the mass production.

The invention discloses slurry for battery negative electrodes, which comprises a carbon negative active material, a conductive agent, a thickening agent, a binding agent and a solvent, the proportion by weight of the carbon negative active material, the conductive agent, the thickening agent, the binding agent and the solvent is 70-130: 1-10: 1-10: 1-10: 80-200, wherein the carbon negative active material is a mixture of native graphite and artificial graphite of the proportion of 0-3: 7-10. The invention further discloses a preparing method of the slurry for battery negative electrodes and a battery manufactured by utilizing the negative electrode slurry. Based on the artificial graphite, the invention creates a proper negative material aqueous formula, which can significantly increase volumetric capacity of the negative electrode based on the artificial graphite on the premise of excellent circulation performance, and thereby a lithium ion battery with high volumetric capacity and long cycle life can be manufactured.

The invention discloses a modified natural graphite material used in lithium ion battery negative electrodes. With a core-shell structure, the material comprises an inner core and a shell coated on the inner-core. The inner-core is composed of natural graphite, and the shell coated on the core is composed of an inner shell and an outer shell. The inner shell is a boron-containing hard carbon layer, and the outer shell is a soft carbon layer. The boron-containing hard carbon layer is coated on natural graphite, and the soft carbon layer is coated on the boron-containing hard layer. The method has advantages of simple technology, suitability for mass production, low graphitization processing temperature, and low cost. With advantages of small specific surface area, high tap density, high first efficiency, high specific capacity, excellent cycling performance, and good rate performance, the modified natural graphite material can be applied in power batteries.

The invention relates to a high-capacity graphite material and a preparation method as well as application thereof. The high-capacity graphite material comprises artificial graphite and natural graphite, wherein the mass ratio of artificial graphite to natural graphite is 20:1 to 1:1. According to the preparation method, the artificial graphite and the natural graphite are uniformly mixed according to a certain mass ratio, and then surface modification is carried out on the mixture. The prepared graphite material has the advantages of high discharge capacity, high first efficiency, long cycle life, low cost and the like; the discharge capacity of the high-capacity graphite material can reach up to more than 350mAh/g (even reach up to more than 368mAh/g); a half-cell of the high-capacity graphite material charges and discharges at the 1C multiple power; after the high-capacity graphite material cycles for 100 times, the capacity retention ratio of the high-capacity graphite material is still more than 90% (even reaches up to more than 96.3%); the first efficiency reaches up to more than 95.5%; and the manufacturing cost is reduced by about 1-10%. The high-capacity graphite material provided by the invention not only can meet the requirement of a lithium ion power battery for the high multiplying power charge-discharge of the material, but also reduces the manufacturing cost of the cathode material of the lithium ion battery.

The invention discloses a silicon monoxide composite cathode material for a lithium ion battery, and a preparation method of the silicon monoxide composite cathode material, aiming at improving the cycle performance. The composite cathode material comprises the components by mass percent: 10-30% of composite particle material and 70-90% of natural graphite or artificial graphite, wherein the composite particle material is silicon monoxide covered by a carbon nano tube and an amorphous carbon coating layer. The method comprises the following steps of: forming the carbon nano tube and the amorphous carbon coating layer on the surface of silicon monoxide to obtain composite particles, and mixing the composite particles with the graphite. Compared with the prior art, the preparation method enables cracking carbon to be covered on the surfaces of silicon monoxide particles, so that the volume effect of the silicon monoxide particles can be effectively inhibited in the charge-discharge process of a battery, the cycle performance is good, the specific capacity is more than 500mAh/ g, and the capacity retention ratio is more than 85% after the circulation is carried out for 100 times; and the preparation method is simple in preparation technology, low in raw material cost and suitable for the cathode material for the high-capacity lithium ion battery.

The present invention relates to the physical or chemical specific purification of natural mineral graphite. This purification is preferably applied to the surface of natural graphite in order to allow the formation of a passivation film during the first electrical discharge or the insertion of lithium in the graphite when the latter is used in a lithium-ion cell. The grinding to a small size before purification allows the optimization of the distribution of the particles, resulting in a more uniform electrode. This grinding is carried out in the presence of the natural impurities of the graphite that play the role of a micro-abrasive and result in a hardness of the graphite that increases its mechanical properties.

This invention discloses one lithium ion second battery compound negative materials and its process method, wherein, the materials comprise modified natural graphite and artificial graphite with quality proportion of 30í†70í½80í†20 and the process method comprises the following steps: a, the natural graphite surface is covered with organism; b, making the thermal process in temperature range of 800íµí½1500íµ for one to six hours; c, mixing the natural graphite with the artificial graphite as proportion of 30í†70í½80í†20.

The invention relates to a preparation method for an acrylic resin/graphene oxide nanometer composite leather finishing agent. In the preparation method, a nanometer graphene oxide suspension liquid is formed through peeling and dispersing; and then the acrylic resin/graphene oxide nanometer composite acrylic resin finishing agent is prepared through in-situ polymerization. The preparation methodcomprises the following specific steps: carrying out oxidization and ultrasonic stripping on natural graphite powder to prepare graphene oxide; adding graphene oxide to a mixed monomer of methyl acrylate, ethyl acrylate, butyl acrylate, acrylic acid and hydroxyethyl acrylate under the action of ultrasonic waves; and carrying out in-situ free radical copolymerization reaction under the action of an initiator ammonium persulfate to obtain the acrylic resin/graphene oxide nanometer composite leather finishing agent. The preparation method has the characteristics that the acrylic resin/graphene oxide nanometer composite leather finishing agent with excellent film-forming hand feel, strength and anti-static performances and no heat bonding and cold brittleness defects is prepared by using the specific laminated structure and performance of graphene oxide.

The invention relates to a capacitor of a lithium ion battery. The capacitor comprises a capacitor shell, an organic electrolyte arranged in the capacitor shell, a winding core formed by isolating a positive plate from a negative plate through an ion permeability microporous membrane and winding, wherein the positive plate and the negative plate are respectively connected with a positive lug and a negative lug and are led out by the positive lug and the negative lug to a positive end and a negative end of the capacitor shell. A negative active material comprises a material A and a material B, wherein the material A comprises at least one of hard carbon and soft carbon, the material B comprises at least one of natural graphite, modified graphite and synthetic graphite, the material A accounts for 50.0%-95.0% of the capacity percentage of the negative active material, and the material B accounts for 5.0%-50.0% of the capacity percentage of the negative active material. The capacitor has the high-energy density characteristic of the lithium ion battery and the high-power density characteristic of a double electric layer capacitor.

The invention discloses a high-voltage high-energy-density lithium ion battery which comprises a positive pole piece, a negative pole piece, a diaphragm, electrolyte and a shell, wherein the positive pole piece comprises a positive active material, a conducting agent, an adhesive and a current collector, and the weight percents of the positive active material, the conducting agent and the adhesion are 92 to 97%: 2 to 3.5%: 1 to 6%; the negative pole piece comprises a negative material, a conducting agent, an adhesive and a current collector, and the weight percents of the negative material, the conducting agent and the adhesive are respectively 90 to 96%, 1 to 5% and 4 to 10%; the lithium ion battery is prepared by adopting modified lithium cobalt oxides (LiCoO2) as the positive active material and the artificial graphite or natural graphite as the negative material and matching the corresponding ceramic diaphragm, high-voltage electrolyte, adhesive and conducting agent. The lithium ion battery not only has high energy density and high discharging platform, but also is good in chemical performance and safety performance and is applicable to the commercialized mass production.

The invention discloses a method for preparing a polyamide-amine in-situ intercalation graphene composite material. The method comprises the following steps of: (1) dispersing graphite in an imidazole-compound-containing organic solvent with ultrasonic, and centrifuging to obtain multi-layer graphene suspension; and (2) polymerizing to generate polyamide-amine in the multilayer graphene by adopting an in-situ polymerization method to prepare the polyamide-amine in-situ intercalation graphene composite material. According to the method, natural graphite is directly subjected to ultrasonic exfoliation in the organic solvent to obtain single-layer or multi-layer graphene suspension, the original sp2 structure of the graphene is slightly damaged because an oxidation step is not carried out, the polyamide-amine in-situ intercalation graphene composite material is prepared by using an in-situ polymerization method, so that graphene laminas are spread, interlamellar spacings are enlarged, the polyamide-amine on the surface of the graphene functionally prevents agglomeration of the graphene laminas, the graphene laminas are uniformly dispersed, and the product has good stability and is hardly precipitated.

The disclosed composite carbon cathode material for Li ion electro-kinetic cell is prepared by bonding composite spherical or near-spherical graphite particle, wherein the material composes by: graphous or natural graphite powder or their mixture, 0.1-5wt% additive, and 1-50wt% bonding agent. The preparation method comprises: granulating, baking, dipping, impregnating, carbonizating, and graphitizing. Compared with prior art, this invention has reversible specific capacity more than 350mAh/g, first circulation coulomb efficiency more than 94%, capacity conservation rate more than 80% after 500 times of circulation, and other well performances.

In an anode material of a lithium-ion secondary battery and its preparation method, a natural graphite, an artificial graphite or both are mixed to form a graphite powder, and the graphite powder is mixed with a resin of a high hard carbon content and processed by a mist spray drying process, and finally added or coated with a special resin material after a carburizing heat treatment takes place to prepare a graphite composite of the anode material of the lithium-ion secondary battery and achieve a smaller surface area of an anode graphite composite of the battery and extended cycle life and capacity.