676 results about "N-methylpyrrolidone" patented technology

An electro-optic assembly comprises an adhesive layer and a layer of electro-optic material. The adhesive layer comprises a polymeric adhesive material and an ionic material having either its cation or its anion fixed to the polymeric adhesive material. The ionic material reduces the volume resistivity of the polymeric adhesive material and is not removed upon heating to 50° C. In a similar electro-optic assembly comprising an adhesive layer and a layer of electro-optic material, the adhesive layer comprises a polymeric adhesive material which has been subjected to dialysis or diafiltration to remove organic species having a molecular weight less than about 3,500, so that the adhesive material has a content of N-methylpyrrolidone not exceeding 500 ppm based upon the total weight of the adhesive layer and layer of electro-optic material.

The invnetion provides a preparation method for a graphene oxide / polyvinylidene fluoride composite ultrafiltration membrane and relates to the preparation method of the graphene oxide / polyvinylidene fluoride composite ultrafiltration membrane. The invention aims to solve the problem of poor hydrophilicity and stain resistance of the existing polyvinylidene fluoride ultrafiltration membrane. The method provided by the invention comprises the following steps of: 1. respectively adding graphene oxide, polyvinylpyrrolidone and polyvinylidene fluoride with N-methylpyrrolidone as solvent, heating and stirring to obtain casting membrane solution; 2. putting the casting membrane solution on a clean glass plate and scrapping to a certain thickness by a coating device, and then immersing distilled water, shedding and drying to obtain the graphene oxide / polyvinylidene fluoride composite ultrafiltration membrane. The preparation method provided by the invention can be applied to the fields of drinking water preparation, food industry, pharmaceutical industry, biotechnology, chemical process and environmental engineering.

The invention relates to a method for modifying aramid fiber by using carbon nano tubes, which comprises the following steps of: selecting an epoxy resin / aramid fiber composite material as a research object, selecting the carbon nano tubes as a surface modification material, forming free amino groups in a certain ratio on the aramid fiber by a chemical modification method, soaking the aramid fiber into N-methylpyrrolidone solution (NMP), and reacting the solution and the surface carboxylation carbon nano tubes with the aid of ultrasonic, wherein part of carbon nano tubes enter the interior of Kevlar fiber, and the other part of carbon nano tubes are fixed on the surface of the fiber through amido bonds formed by the carbon nano tubes and amino, thus, a aramid fiber complex inside and outside which the carbon nano tubes are doped is formed. Single fiber tensile test results and single fiber pull-out test results show that the mechanical property of the modified aramid fiber and the interface bonding strength with the epoxy resin are improved.

The invention discloses a high-performance flat-type cellulose acetate / graphene blend forward osmosis membrane. 5 to 25 percent by weight of cellulose acetate, 1 to 15 percent by weight of additives, 0.01 to 2 percent by weight of graphene and mixed solvent of dimethylformamide, dimethylacetamide, or N-methylpyrrolidone and acetone are added into a dissolving tank according to a given sequence and are stirred and dissolved for 2 to 18 hours at the temperature of 5 to 75 DEG C to be uniformly mixed so as to prepare a forward osmosis membrane casting solution; the high-performance flat-type cellulose acetate / graphene blend forward osmosis membrane is prepared on a supporting material by adopting a phase inversion method. According to the forward osmosis membrane, 1M NaCl is used as a driving liquid, the deionized water is used as a raw material solution, the flux of pure water of the forward osmosis membrane is more than 21L / m<2> within the test time of one hour, and the salt flux in the reverse direction is less than 3.5g / m<2>.

A polishing composition which achieves surfaces with high planarity and the reduction of corrosions in the wiring metal surface at the same time is provided.Such compositions include(A) an oxidizing agent;(B) at least one acid selected from an amino acid, a carboxylic acid of no more than 8 carbon atoms, and an inorganic acid;(C) a sulfonic acid having a concentration of 0.01% by mass or more and having an alkyl group of 8 or more carbon atoms;(D) a fatty acid having a concentration of 0.001% by mass or more and having an alkyl group of 8 or more carbon atoms; and(E) at least one compound selected from a pyridine carbonyl compound, a nonionic water-soluble polymer, 2-pyrrolidone, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, gramine, adenine, N,N′-diisopropylethylenediamine, N,N′-bis(2-hydroxyethyl)ethylenediamine, N,N′-dibenzylethylenediamine, and N,N′-diphenylethylenediamine.

The invention relates to a separation and recovery method for n-methylpyrrolidone (NMP) and a lithium chloride catalyst during polyphenylene sulfide producing. The method is characterized by: directly carrying out vacuum distillation for a polyphenylene sulfide polycondensation mother liquid until the polyphenylene sulfide polycondensation mother liquid is dried to recover a solvent of the NMP, wherein the NMP can be used in the next recycling production; adding water to the distilled residues, then heating to a temperature of 40 DEG C, carrying out stirring and completely dissolving the distilled residues, carrying out filtering and washing the filter residues, mixing the resulting filtrate and the washing solution, and analyzing lithium content in the mixed solution; adding the mixed solution to a phosphoric acid solution or a sodium aluminate solution, wherein the phosphoric acid solution or the sodium aluminate solution has a lithium reaction equivalent of 105-115%, then completely stirring to enable lithium phosphate or lithium aluminate to be precipitated completely, then carrying out steps of filtering, washing, drying for the lithium phosphate or the lithium aluminate to recover the lithium salt having a purity more than 97%. According to the present invention, the operation of the method is simple; the cost is low; the recovered NMP and the recovered lithium salt havehigh purities.

The invention relates to a graphene / conductive polymer composite film and a preparation method thereof. The graphene / conductive polymer composite film comprises products prepared by the following reaction: 1) preparing graphite oxide from graphite by a chemical oxidation method; 2) adding an oxidant ammonium persulfate into monomer containing acid solution to prepare conductive polymer; 3) performing ultrasonic dispersion on the graphite oxide and the conductive polymer in N-methylpyrrolidone, adding a reducing agent, and stirring; 4) coating solution prepared by step 3) on the surface of a substrate to form a film, washing and drying; and 5) repeating the step 4) until the film has the required thickness. The graphene / conductive polymer composite film and the preparation method have the advantages that: 1) the formed graphene / conductive polymer composite film has good electric conduction and antistatic property, and has the conductivity between 1*10<-3> and 1*10<2>S / cm; 2) the conjugated structure of the grapheme and the conductive polymer ensures that the grapheme and the conductive polymer have high compatibility; 3) the composite film has controllable thickness; and 4) the preparation method has simple conditions and easy operation.

A binder for electrode of lithium ion secondary battery, comprised of a copolymer composed of 15 to 80 weight % of units from ethylenically unsaturated monomer (A) whose homopolymerization yields a polymer soluble in N-methylpyrrolidone (NMP) and 20 to 85 weight % of units from ethylenically unsaturated monomer (B) whose homopolymerization yields a polymer insoluble in NMP, which copolymer exhibits a swelling degree of 4 or below, in an electrolyte obtained by dissolving LiPF6 in the concentration of 1 mol / liter into a solvent of 1:2 (volume ratio at 20° C.) mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) . This binder for electrode of lithium ion secondary battery enables obtaining an electrode having a flexible electrode layer excelling in binding properties with industrial advantage.

The invention discloses a recycling method of retired lithium iron phosphate battery positive-electrode materials. The method includes the steps: soaking and dissolving binding agents in an N-methylpyrrolidone solvent by the aid of the N-methylpyrrolidone solvent to strip LiFePO4 positive-electrode materials and aluminum foil fluid collectors; mixing the stripped waste LiFePO4 positive-electrode materials and binding agents; coating a carbon fabric or titanium mesh with mixture of the waste LiFePO4 positive-electrode materials and the binding agents to serve as a positive electrode; taking a graphite electrode as a negative electrode; building an electrolytic tank in electrolyte solution; driving lithium removal by the aid of a direct-current electric field to collectively recycle lithiumions and lithium removal product iron phosphate. According to the method, lithium removal is driven and adjusted by the direct-current electric field, lithium can be basically completely removed, subsequent treatment of the electrode materials after lithium removal is performed, so that treated electrode materials can be converted into the iron phosphate, and the iron phosphate can be used for preparing lithium iron phosphate positive-electrode materials and is good in electrochemical performance. The method is simple and convenient in operation process, controllable in condition, high in recycling rate and environmentally friendly, and popularization and application are facilitated.

The present invention discloses a positive electrode sheet of a lithium iron phosphate type lithium ion battery, and a preparation method thereof. According to the present invention, a positive active material coating comprise a nano-lithium iron phosphate positive active material coating a and a nano-lithium iron phosphate positive active material coating b; nano-lithium iron phosphate positive active material slurry a is coated on a current collector; nano-lithium iron phosphate positive active material slurry b is coated on the nano-lithium iron phosphate positive active material coating a; electrode lugs are spot welded on reserved blank of the current collector. The method comprises the following steps that: A, a lithium iron phosphate positive active material is respectively mixed with a nano carbon black conductive agent, a polyvinylidene difluoride agglomerant and a N-methylpyrrolidone solvent according to the ratio to prepare the nano-lithium iron phosphate positive active material slurry a and the nano-lithium iron phosphate positive active material slurry b; B, the slurry prepared from the lithium iron phosphate are coated on a side or both sides of the current collector having a certain thickness to form the coatings; C, the positive electrode sheet having coatings is prepared. The lithium iron phosphate type lithium ion battery has characteristics of high capacity, high rate, good effect. With the positive electrode sheet provided by the present invention, the service life of the lithium ion battery is prolonged.

A composition for intranasal delivery of a drug comprising: includes: (i) the drug; and (ii) a non-aqueous vehicle containing (a) propylene glycol and at least one additional solvent selected from N-methylpyrrolidone, propylene carbonate, dimethyl sulfoxide and at least one propylene glycol fatty acid ester; (b) from about 40 to 100% by volume of N-methylpyrrolidone; or (c) from about 40 to 100% by volume of dimethyl sulfoxide (DMSO).

An exemplary printable composition comprises a liquid or gel suspension of a plurality of metallic nanofibers; a first solvent; and a viscosity modifier, resin, or binder. In various embodiments, the metallic nanofibers are between about 10 microns to about 100 microns in length, are between about 10 nm to about 120 nm in diameter, and are typically functionalized with a coating or partial coating of polyvinyl pyrrolidone or a similar compound. An exemplary metallic nanofiber ink which can be printed to produce a substantially transparent conductor comprises a plurality of metallic nanofibers; one or more solvents such as 1-butanol, ethanol, 1-pentanol, n-methylpyrrolidone, cyclohexanone, cyclopentanone, 1-hexanol, acetic acid, cyclohexanol, or mixtures thereof; and a viscosity modifier, resin, or binder such as polyvinyl pyrrolidone or a polyimide, for example.

An exemplary printable composition comprises a liquid or gel suspension of a plurality of metallic nanofibers or nanowires; a first solvent; and a viscosity modifier, resin, or binder. In various embodiments, an exemplary metallic nanowire ink which can be printed to produce a substantially transparent conductor comprises a plurality of metallic nanowires at least partially coated with a first polymer comprising polyvinyl pyrrolidone having a molecular weight less than about 50,000; one or more solvents such as 1-butanol, ethanol, 1-pentanol, n-methylpyrrolidone, cyclohexanone, cyclopentanone, 1-hexanol, acetic acid, cyclohexanol, and mixtures thereof; and a second polymer or polymeric precursor such as polyvinyl pyrrolidone or a polyimide, having a molecular weight greater than about 500,000.

The invention belongs to the technical field of inorganic functional nano materials, and particularly relates to a curved-surface molybdenum disulfide nanosheet and a preparation method thereof. The preparation method comprises the following steps: 1. dissolving a molybdenum source and a sulfur source in a mixed solution composed of deionized water and N-methylpyrrolidone, and carrying out heat treatment to obtain a reaction product A, wherein the mole ratio of the sulfur source to the molybdenum source is 1:8-1:32, the volume ratio of the deionized water to the N-methylpyrrolidone in the mixed solution is 1:4-4:1, the heat treatment temperature is 180-240 DEG C, and the heat treatment time is 5-30 hours; and 2. alternately washing the reaction product obtained in the step 1 with water and ethanol, and drying at 50-80 DEG C to obtain the curved-surface molybdenum disulfide nanosheet. By using the N-methylpyrrolidone as the solvent, the method can be used for quickly preparing the curved-surface molybdenum disulfide nanosheet by simple magnanimous steps.

An electrophotographic photosensitive member wherein a charge generating layer of the electrophotographic photosensitive member includes a gallium phthalocyanine crystal in which an organic compound is contained, wherein the organic compound is at least one compound selected from the group consisting of dimethylsulfoxide, N,N-dimethylformamide, N-methylformamide, N-propylformamide, N-vinylformamide and N-methylpyrrolidone, the content of the organic compound is 0.1% by mass or more and 2.0% by mass or less based on a gallium phthalocyanine in the gallium phthalocyanine crystal, and a charge transporting layer of the electrophotographic photosensitive member includes a polycarbonate resin having structural units represented by formulae (1) and (2).

The invention relates to a method for preparing waterborne polyurethane taken as a waterborne epoxy hardener. The method comprises the following steps of: adding aliphatic polyisocyanate into low polymer polyalcohol; dissolving dimethylolpropionic acid taken as a hydrophilic chain extender in N-methylpyrrolidone; adding dibutyltin dilaurate taken as a catalyst into the mixture; stirring the mixture and raising the temperature to a certain extent to prepare a preformed polymer containing a terminated isocyanate group; cooling the prepared preformed polymer to room temperature; adding triethylamine into the preformed polymer to perform neutralization reaction for a certain period of time; and adding an appropriate amount of distilled water and violently stirring the mixture to emulsify the mixture; and adding a polyamine chain extender to perform chain extension reaction for a certain period of time to obtain amino-terminated waterborne polyurethane emulsion. The method has the advantages of preparing polyurethane emulsion which can be directly applied to curing epoxy resin, realizing a simple synthetic method and more easily controlled operation, enhancing the compatibility of epoxy resin emulsion with a curing agent, enabling a synthetized paint product to achieve the advantages of polyurethane and the epoxy resin and realizing high performance of paint.

Disclosed is a polishing composition which realizes both high planarity and reduction of corrosion in the surface of a wiring metal. Specifically disclosed is a polishing composition containing an oxidizing agent (A), at least one or more acids (B) selected from amino acids, carboxylic acids having 8 or less carbon atoms and inorganic acids, a sulfonic acid (C) having a concentration of not less than 0.01% by mass and an alkyl group having 8 or more carbon atoms, a fatty acid (D) having a concentration of not less than 0.001% by mass and an alkyl group having 8 or more carbon atoms, and at least one or more compounds (E) selected from pyridinecarbonyl compounds, nonionic water-soluble polymers, 2-pyrrolidone, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, gramine, adenine, N,N'-diisopropylethylenediamine, N,N'-bis(2-hydroxyethyl)ethylenediamine, N,N'-dibenzylethylenediamine and N,N'-diphenylethylenediamine.

The invention discloses a diamond nonstick coating composition and a preparation method thereof. The coating composition comprises a primer and a finishing coat, wherein the primer comprises the following components in percentage by weight: 1-5% of carbon black, 5-10% of a surfactant, 10-32% of polytetrafluoroethylene, 10-20% of N-methylpyrrolidone, 30-50% of water, 0-5% of diamond powder and 5-15% of bonding resin, totally 100%; the finishing coat comprises the following components in percentage by weight: 5-20% of a surfactant, 35-50% of polytetrafluoroethylene, 20-40% of water, 0-5% of diamond powder and 15-19% of an organic solvent, totally 100%; the percentages by weight of the diamond powder in the primer and finishing coat are not zero at the same time. The diamond nonstick coating composition disclosed by the invention has excellent coating pencil hardness, heat conductivity and wear resistance.

The invention provides aqueous polyurethane matting resin. According to the aqueous polyurethane matting resin, any matting material does not need to be added, coating is uniform, the matting effect is good and the service life is long. The aqueous polyurethane matting resin contains following components in parts by weight: 10-18 parts of diisocyanate, 0.5-5 parts of dimethylolpropionic acid (DMPA), 35-60 parts of dihydric alcohol, 0.05-1 part of organic bismuth catalyst, 0.5-5 parts of dimethylethanolamine, 0.5-10 parts of 2-[(2-aminoethyl)amino]sodium sulfonate, 0.5-5 parts of hydrazine hydrate, 1-10 parts of N-methylpyrrolidone catalyst and 104-180 parts of de-ionized water. The invention further provides a preparation method of the aqueous polyurethane matting resin.

The invention provides a method for preparing environment-friendly aromatic oil from catalytic cracking slurry oil. The environment-friendly aromatic oil which meets the European 2005 / 69 / EC directive is prepared by performing repeated extraction with double solvents on the catalytic cracking slurry oil by using an alkyl solvent with small polarity and the solvents such as furfural, N-methylpyrrolidone, dimethyl sulfoxide and the like with large polarity. Toxic polycyclic aromatic hydrocarbon in the obtained environment-friendly aromatic oil is less than 3 percent, and the benzopyrene content is less than 0.1ppm, so the oil can be used as environment-friendly rubber filling oil and environment-friendly aromatic oil for other purposes.

A surface enhanced raman spectroscopy substrate of continuous three dimensional structural nano silver and a preparation method thereof relate to a surface enhanced raman spectroscopy substrate of nano silver and a preparation method thereof. The invention solves the problems of the surface enhanced raman spectroscopy substrate of nano silver prepared by the prior art, such as poor signal uniformity, low sensitivity, complicated preparation technique and high cost. The substrate consists of a polyaniline film, a nano gold layer and a three dimensional nano silver layer sequentially from bottom to top. The preparation method of the substrate comprises the steps of: dissolving undoped polyaniline powder in N-methylpyrrolidone to form homogeneous solution, spreading the solution on a glass substrate, conducting curing to obtain the polyaniline film; later dipping the polyaniline film in gold-bearing solution to obtain the nano gold layer; and then dipping the polyaniline film coated with the nano gold layer in silver nitrate soluation for reaction to obtain the surface enhanced raman spectroscopy substrate of the continuous three dimensional structural nano silver. The substrate can be used for detection of organic molecules and biological molecules with ppm concentration and has uniform signal response, high sensitivity, simple and fast method, and low cost.

Provided is an electrophotographic photosensitive member, including in the following order: a support; a charge-generating layer; and a charge-transporting layer, in which: the charge-generating layer includes a gallium phthalocyanine crystal in which an organic compound is contained; the organic compound is at least one compound selected from the group consisting of dimethyl sulfoxide, N,N-dimethylformamide, N-methylformamide, N-propylformamide, N-vinylformamide, and N-methylpyrrolidone; a content of the organic compound is 0.1% by mass or more and 1.5% by mass or less with respect to a mass of gallium phthalocyanine in the gallium phthalocyanine crystal; and the charge-transporting layer comprises at least one compound selected from the group consisting of a compound represented by the formula (1), a compound represented by the formula (2), a compound represented by the formula (3), and a compound represented by the formula (4).

A preparation method for the p-phenylene terephthalamide p-phenylenediamine with high molecular weight, which comprises the following steps: adding anhydrous calcium chloride and N-methylpyrrolidone (NMP) to a reactor according to the weight proportion of 4-20: 100; adding proper amount of p-phenylenediamine (PPD), starting stirring, stirring for 30min at room temperature; inletting cooling medium to the reactor jacket to reduce temperature; reducing the system temperature to 0-15 DEG C below zero; adding the first batch of terephthaloyl chloride (TPC), continually stirring for 30min; reducing the temperature to 0-15 DEG C below zero again; adding the second batch of TPC; stirring quickly; stopping reaction after the system occurs pole-climbing and gel and is stirred to prepare the p-phenylene terephthalamide p-phenylenediamine. By adding the reactant TPC by two batches, the method of the invention can effectively control the reaction temperature; by cooling and reducing the temperature of the system, the method reduces the occurrence of side reaction and prepares the p-phenylene terephthalamide p-phenylenediamine with higher molecular weight and better color and luster.

The invention relates to a paint remover for plane aluminium alloy skin depainting treatment; the paint remover comprises more than two kinds of 70-80 parts of main solvent, two kinds of 12-18 parts of accelerators, 4-5 parts of thickening agents and 0.5-2 parts of corrosion inhibitors; the main solvent includes N-methylpyrrolidone (N-P), alpha-pyrrolidone (alpha-P), benzyl alcohol and dimethyl sulfoxide; the accelerator is soluble organic acid with lower than 1000 of molecular weight, and the molecular weight includes methanoic acid, salicylic acid, p-toluenesulfonic acid and terephthalic acid; the thickening agent is carboxymethylcellulose or carboxyethyl cellulose; and the corrosion inhibitor is p-methyl pyrrodiazole, thiazole and benzotriazole. The paint remover can remove the paint film on the surface of the plane aluminium alloy skin in a short time (within 35min) in a in-situ way, and the paint remover has no over etching to the surface of the aluminium alloy and has recoatability.

The invention relates to a preparation method of lithium battery anode slurry. The preparation method comprises the following steps of 1, preparing a glue solution through the processes of putting a right amount of N-methylpyrrolidone (NMP) and a right amount of polyvinylidene fluoride (PVDF) into a vacuum dispersator, and carrying out vacuum-pumping and stirring, b, carrying out preblend of a conductive agent, an active material and Li2CO3, adding the mixture of the conductive agent, the active material and Li2CO3 into the glue solution obtained by the step 1, and stirring for 3 to 5 hours, and c, testing viscosity of the solid-liquid mixture obtained by the step b, and adding N-methylpyrrolidone (NMP) into the solid-liquid mixture to adjust the viscosity of the solid-liquid mixture so that the viscosity the solid-liquid mixture satisfies a coating requirement. The preparation method of the lithium battery anode slurry has the advantages of simple operation and preparation processes. The preparation method of the lithium battery anode slurry also has the advantages of improving production efficiency, reducing energy consumption, reducing a total amount of gas produced by subsequent formation of a lithium battery prepared from the lithium battery anode slurry, increasing battery reversible capacity, and realizing the optimal cycle performance.

A semiconductor wafer cleaning formulation for use in post plasma ashing semiconductor fabrication comprising at least one organic chelating agent and at least one polar solvent, wherein the chelating agent and polar solvent are in sufficient amounts to effectively remove inorganic compound residue from a semiconductor wafer. Preferably, the chelating agent is selected from the group consisting of 2,4-Pentanedione, Malonic acid, Oxalic acid, p-Toluenesulfonic acid, and Trifluoroacetic acid; and the polar solvent is selected from the group consisting of Water, Ethylene glycol, N-Methylpyrrolidone (NMP), Gamma butyrolactone (BLO), Cyclohexylpyrrolidone (CHP), Sulfolane, 1,4-Butanediol, and Butyl carbitol.

The invention relates to a purifying method of N-methylpyrrolidone, comprising the following steps: absorbing aminomethane from N-methylpyrrolidone to be purified through an activated-charcoal column; then removing water through a molecular sieve column; and finally removing solid particulates through ultrafiltration to obtain a finished product. The purifying method of N-methylpyrrolidone is used for purifying the N-methylpyrrolidone by utilizing a solid (activated charcoal and a molecular sieve) absorbing method instead of a distillation method. The method has simple process route and easy operation; the activated-charcoal column is used for removing the aminomethane in the N-methylpyrrolidone so that the content of the aminomethane reach below 0.005 percent, and the molecular sieve column ensures that the water content in the N-methylpyrrolidone is lowered to below 0.01 percent, thereby efficiently removing impurities. The N-methylpyrrolidone purified by the method has stable quality, high yield of at least 95 percent and low manufacturing cost; and the activated charcoal and the molecular sieve are recyclable after losing efficacy, thereby having the advantages of cost saving and environment protection.

This invention discloses a method for resolving amlodipine. The method uses tartaric acid as the chiral reagent, and N-methylpyrrolidone as the chiral aid. The method has such advantages as high resolving rate, high product optic purity and simple process, and is suitable for mass production.

The invention discloses a negative pole made of a silicon / graphite nanosheet composite material of a lithium ion battery, which comprises the following components in percentage by mass: 85 to 95 percent of nanometer silicon powder-graphite nanosheet composite material, and 5 to 15 percent of polyvinylidene fluoride, wherein the content of nanometer silicon powder is between 20 and 75 percent in the nanometer silicon powder-graphite nanosheet composite material. A preparation method thereof comprises the steps of: preparing graphite oxide, preparing a mixed dispersion system of the nanometer silicon powder and graphite oxide nanosheets; adding a reducing agent, namely hydrazine hydrate into the mixed dispersion system of the nanometer silicon powder and the graphite oxide nanosheets, and reducing the graphite oxide nanosheets into graphite nanosheets to obtain a composite material of the nanometer silicon powder and the graphite nanosheets; and fully mixing the composite material of the nanometer silicon powder and the graphite nanosheets with N-methylpyrrolidone sol of the polyvinylidene fluoride, blending the mixture into paste, evenly coating the paste onto a copper coil, and performing drying and roller compaction. The negative pole made of the silicon / graphite nanosheet composite material of the lithium ion battery has high electrochemical capacity and good cycling stability performance.

The invention provides a preparation method of polycondensed asphalt, a preparation method of needle coke and a needle coke. The preparation method of polycondensed asphalt comprises the following steps: S1. extracting asphalt in coal liquefication residues with an extraction solvent to obtain refined asphalt, wherein the extraction solvent is composed of one or more of 120-300 DEG C distillate segment coal liquefied oil, N-methylpyrrolidone, tetrahydrofuran, quinoline, pyridine and anthracene oil; and S2. carrying out polycondensation reaction on the refined asphalt to form the polycondensed asphalt. The refined asphalt is separated from the coal liquefication residues in an extraction mode, and such process can adopt the currently common extraction technique having high operability; the obtained refined asphalt is mainly composed of polycyclic condensed aromatics, has the characteristics of high aromaticity, high carbon content and high polymerization or crosslinking tendency, and is suitable to be used as a precursor of a polycondensed asphalt raw material for preparing needle coke; and the invention finds out a new application direction for coal liquefication residues.