1629results about "Nano-carbon" patented technology

The present disclosure relates to a carbon-based nanomaterial composition that may be formed from a gas mixture and a sulfur powder. The gas mixture may include a carbon based gas, an oxygen gas, and a hydrogen gas. The carbon-based nanomaterial composition may include sulfur doped nanospheres.

The invention discloses a synthesis method of amphiphilic quantum dots and application of the amphiphilic quantum dots in nano oil displacement, and belongs to the field of nano oil displacement. The synthesis method comprises the following steps: heating a mixture containing a carbon source and a nitrogen source in an air atmosphere for reaction, and centrifuging, filtering and drying a reaction product to obtain the amphiphilic quantum dots, the carbon source is selected from at least one of glucose, mannose, citric acid, lignin, chitosan and starch; the nitrogen source is selected from at least one of alkylamine, and the carbon chain length of the alkylamine is C6 to C12. The synthesis method is simple, heating of a high-pressure reaction kettle is not needed, the technological process is simple, and the method is suitable for large-scale industrial production; the series of amphiphilic carbon quantum dots show better solubility and higher absolute fluorescence quantum yield in water and various organic solvents.

The invention discloses a high-entropy nanoparticle catalytic material with a metal atom shell structure and a preparation method of the high-entropy nanoparticle catalytic material, and belongs to the technical field of preparation of catalytic materials. The preparation method comprises the following steps: dispersing a metal salt and a nanofiber precursor in an organic solvent, and carrying out electrostatic spinning to obtain a nanofiber membrane; and then calcining and pre-oxidizing the nanofiber membrane, and then carbonizing and calcining to obtain the nanofiber membrane. Wherein the selection principle of the metal salt is as follows: (n-1)-(n-2) metals are selected as an alloy substrate, and the sum of the mixing enthalpy of elements of the alloy substrate is not greater than-5kJ mol <-1 >; one or two metal elements serve as a precipitated phase, and the sum of the mixing enthalpy of the metal elements of the precipitated phase and the elements of the alloy substrate is larger than 20 kJ mol <-1 >; the high-entropy nanoparticle catalytic material obtained by the method shows relatively high catalytic activity and stability, and the method has wide universality.

The invention relates to a sodium ion battery, and belongs to sodium ion batteries. The battery cell of the sodium-ion battery comprises a positive plate, a negative plate and an electrolyte, the active material of the positive plate is carbon-coated aluminum-doped sodium ferric sulfate; the chemical formula of the aluminum-doped sodium ferric sulfate is Na < 2 + 2y > Fe < 2-x-y > Al < x > (SO4) 3, x is more than or equal to 0.01 and less than or equal to 0.05, and y is more than or equal to 0.1 and less than or equal to The particle size of the carbon-coated aluminum-doped sodium ferric sulfate ranges from 50 nm to 100 nm; the weight ratio of a carbon coating layer in the carbon-coated aluminum-doped sodium ferric sulfate is 1%-5%; the active material of the negative plate is carbon-coated sodium titanate; the specific surface area of the carbon-coated sodium titanate is 20 m < 2 > / g to 25 m < 2 > / g; the weight ratio of a carbon coating layer in the carbon-coated sodium titanate is 0.5%-3%. Volume expansion is jointly inhibited through structural stability of positive and negative electrode materials, and the cycle life is prolonged.

The invention relates to a carbon quantum dot for strengthening and promoting growth of microalgae and application thereof. In the process of preparing the carbon quantum dots by a conventional hydrothermal method, a precursor mixture is subjected to acidification modification in advance, the pH value is adjusted to 2 by using nitric acid, and then a hydrothermal reaction is performed, so that the prepared carbon quantum dots have the capability of promoting the growth of microalgae. However, if other acids are adopted or pH adjustment is not in place, the effect cannot be achieved, and even the inhibition effect can be achieved. The obtained product is good in effect and stable in performance, no special reaction device needs to be additionally arranged in the acidification modification process, and the method has the advantages that operation is easy and convenient, raw materials are easy to obtain, and the process can be quantified; the method is simple and convenient in process operation, has universality and is easy for industrial production.

The invention provides a nitrogen-doped biomass-based fluorescent carbon quantum dot, a preparation method and application, and relates to the technical field of carbon nanomaterials, the method comprises the following steps: mixing a biomass material and deionized water under an ultrasonic condition, adding a nitrogen source, and carrying out ultrasonic dispersion to obtain a uniformly dispersed to-be-reacted solution; reacting the to-be-reacted solution at a preset temperature for a preset time to obtain a mixed product solution; and filtering and dialyzing the mixed product solution to obtain the nitrogen-doped biomass-based fluorescent carbon quantum dot solution. The nitrogen-doped biomass-based fluorescent carbon quantum dot prepared by the method shows a stable fluorescent effect and good water solubility, the free radical clearance rate can reach 90% or above, and the antibacterial rate can reach 99% or above. The method can be used in the fields of drug sustained release, bioimaging and the like.

The invention discloses an oxygen-sulfur double-vacancy modified SnO2 / SnS2 / C nano material as well as a preparation method and application thereof, and belongs to the technical field of electrode materials. The preparation method comprises the following steps: mixing a structure regulating agent with tin salt, dropwise adding alkali liquor, stirring, and carrying out suction filtration to obtain Sn6O4 (OH) 4; the preparation method comprises the following steps: adding glucose and polyvinylpyrrolidone into distilled water, stirring to form a uniform solution, adding Sn6O4 (OH) 4 into the uniform solution, stirring, and carrying out ultrasonic and hydrothermal reaction to obtain SnO2 / glucose; and calcining the SnO2 / glucose and a sulfur source in an inert atmosphere to obtain the SnO2 / SnS2 / C nano material modified by oxygen and sulfur double vacancies. The SnO2 / SnS2 / C disclosed by the invention is used for a lithium / sodium ion battery negative electrode, can effectively relieve volume expansion of tin-based oxysulfide and improve the conductivity of an electrode material, and shows high charge-discharge specific capacity, excellent rate capability and high-rate long-cycle stability.

The invention discloses a solid-state capacitor and a preparation method thereof, and the preparation method comprises the following steps: (1) core package winding: interposing electrolytic paper between an anode foil and a cathode foil, and winding to form a core package; (2) a repairing step: immersing the core package into a formation liquid for repairing treatment; (3) a drying step: carrying out drying treatment on the core package in the step (2); (4) an impregnation step: immersing the core package in the step (3) into a first impregnation liquid for impregnation treatment; performing drying; immersing into a second impregnation liquid for impregnation treatment, and drying; (5) a polymerization step: immersing the core cladding in the step (4) into an oxidation liquid for polymerization; and (6) assembling, girdling and aging treatment.

The invention relates to the technical field of lithium ion batteries, in particular to a carbon source mixed gas CVD coated silicon-carbon negative electrode material, a preparation method and a lithium ion battery. The preparation method comprises the following steps: 1) preparation of a silicon-carbon material: placing porous carbon in equipment, regulating and controlling the gas speed and the dynamic rotation speed of the equipment to uniformly disperse the porous carbon, heating to 380-650 DEG C, and introducing silane mixed gas with the concentration of 5-50% to form the silicon-carbon material; and 2) coating the silicon-carbon material with mixed gas carbon: introducing mixed gas sources with different proportions into equipment, regulating and controlling the gas speed and the dynamic rotation speed of the equipment to uniformly disperse the mixed gas sources, and heating to 450-700 DEG C to realize uniform carbon coating on the surface of the silicon-carbon material. According to the invention, the problem of explosion caused by self-polymerization reaction of single acetylene is solved; and moreover, the uniform carbon coating isolates the side reaction problem caused by direct contact between the electrolyte and the nano silicon, and the stability of the silicon-carbon material is improved.

The invention provides an amphiphilic carbon dot, a carbon nanofluid and application of the amphiphilic carbon dot and the carbon nanofluid, and belongs to the technical field of nanomaterial oil displacement, and the amphiphilic carbon dot is prepared by taking alkylphenol polyoxyethylene ether and glucose as raw materials to perform solvothermal reaction; the alkylphenol polyoxyethylene ether comprises octylphenol polyoxyethylene ether and / or nonylphenol polyoxyethylene ether; the mass ratio of the alkylphenol polyoxyethylene ether to the glucose is 1: (0.1-2). According to the invention, alkylphenol polyoxyethylene ether and glucose are taken as raw materials, and simple preparation of the amphiphilic carbon dots with high surface and interface activity is realized. The amphiphilic carbon dots provided by the invention show good surface and interface activity at high temperature and high salinity. According to the carbon nanofluid provided by the invention, the amphiphilic carbon dots and the zwitterionic surfactant are compounded, so that the stability of a carbon nanofluid oil displacement system at high temperature and high salt can be further improved, the crude oil recovery rate is increased, and efficient yield-increasing development of high-temperature and high-salt deep oil reservoirs is realized.

The invention relates to an external composition for hair growth regulation and a preparation method thereof, and belongs to the technical field of cosmetics and medicines. The composition disclosed by the invention comprises nano mesoporous carbon for enhancing permeation, various surface functional modifications on the nano mesoporous carbon, minoxidil, protein fragments, polypeptides, oligopeptides, amino acids, dutasteride, bimatoprost, traditional Chinese medicine extracts, vitamins, caffeine, nucleosides, growth factors and various auxiliary functional components. Wherein the pore diameter of mesopores of the nano mesoporous carbon for enhancing permeation is 2-30 nm, the total pore volume of the mesopores is 1.5-3.5 cm < 3 > / g, and the particle size of the nano mesoporous carbon is 50-200 nm. The prepared nano mesoporous carbon is granular, controllable in size, stable in structure, free of irritation to skin, capable of keeping inert to various active ingredients in the composition, capable of enhancing absorption and permeation of other ingredients on the skin, wide in application range, capable of compounding various types of active ingredients and high in biological safety.

The invention belongs to the technical field of lithium battery materials, and particularly relates to a lithium trifluoromethanesulfonate in-situ doped graphdiyne composite material and a preparation method and application thereof. The preparation method of the lithium trifluoromethanesulfonate in-situ doped graphdiyne composite material adopts a one-step in-situ synthesis method, and specifically comprises the following steps: adding hexaacetylene benzene and lithium trifluoromethanesulfonate into a solvent, mixing, adding a catalyst, carrying out a heating reaction, and carrying out post-treatment on the obtained reactant to obtain the lithium trifluoromethanesulfonate in-situ doped graphdiyne composite material. Finally, the lithium trifluoromethanesulfonate in-situ doped graphdiyne composite material is obtained. The preparation method of the lithium trifluoromethanesulfonate in-situ doped graphdiyne composite material provided by the invention is simple in process, the prepared composite material is good in interface stability, and when the composite material is applied to a negative electrode of a lithium ion battery, the electrochemical performance of the battery can be improved, and the service life of the battery can be prolonged.

The invention discloses a carbon quantum dot loaded diatom electrocatalyst and a preparation method and application thereof. The preparation method comprises the following steps: dissolving and mixing diethylene triamine pentaacetic acid and salt of metal M1 in water, and performing reflux reaction to obtain a complex solution of the metal M1; adding salt of metal M2 for reflux reaction, filtering after the reaction is finished, and removing a solvent from filtrate to obtain a solid complex of bimetals M1 and M2; drying and calcining to obtain a diatomic electrocatalyst precursor; and carrying out post-treatment and freeze-drying to obtain the diatomic electrocatalyst. The carbon quantum dot loaded bimetallic atom site catalyst is obtained by a preparation strategy of coupling molecular design and quantum dot confinement, and is used for research on deep reduction of carbon dioxide into methane through electro-catalysis. The obtained catalyst has excellent methane production activity on an electro-catalysis carbon dioxide reduction reaction under an alkaline condition and a flow cell configuration, and still has relatively good stability under long-term work.

The present invention belongs to the technical field of batteries. Disclosed are an iron(III) phosphate material, a preparation method therefor, and a use thereof. The iron(III) phosphate material comprises a carbon quantum dot core located internally and an iron(III) phosphate shell formed on the surface of the carbon quantum dot core, and the surface of the iron(III) phosphate shell is provided with a carbon coating layer formed from a carbon-containing dispersing agent. The iron(III) phosphate material is nanoscale iron(III) phosphate and has a uniform crystal size. The preparation method therefor comprises the following steps: mixing a first mixed solution containing a divalent iron salt and carbon quantum dots, a second mixed solution containing a phosphate and a dispersing agent, and an oxidizing agent to undergo a reaction to obtain iron(III) phosphate dihydrate; and annealing and calcining the iron(III) phosphate dihydrate. The iron(III) phosphate material can be further used for preparing a lithium iron phosphate positive electrode material and a battery.

The invention belongs to the field of carbon nanomaterials, and provides a method for preparing a carbon quantum dot material doped with elements such as silicon and aluminum by oxidative depolymerization and stripping of coal gangue. Comprising the steps of screening and matching of coal gangue, oxidative depolymerization stripping, centrifugal dialysis membrane filtration and modification, drying and the like, raw materials and all the steps are specifically set, and the particle size or fluorescence performance of fluorescent carbon dots can be specifically selected and set according to selective oxidative depolymerization stripping conditions. The main particle size of the prepared multi-inorganic-element doped carbon quantum dot material is kept within the range of 1.5-2.0 nm, the structure is stable, the optical performance also meets the requirements, and the material can be further modified and is expected to be applied to the fields of photovoltaic equipment, biological imaging, photocatalytic degradation of organic pollutants or sensing and the like.

The invention discloses a preparation method of ocimum gratissimum carbon dots and application of the ocimum gratissimum carbon dots in antibacterial drugs and food preservation. The preparation method of the ocimum gratissimum carbon dots comprises the following steps: performing steam distillation on ocimum gratissimum leaves to remove essential oil, drying in the shade, and crushing; adding an alcohol solvent into the powder, extracting, filtering, concentrating and drying to obtain an alcohol extract; dispersing the alcohol extract in distilled water, and stirring and pyrolyzing on a heating table; and diluting the pyrolysis product with distilled water, centrifuging, taking supernate, filtering with a filter membrane, dialyzing, and freeze-drying to obtain the carbon dots. The obtained carbon dots have a carbon dot-vesicle coexisting structure, and the average particle size is 5.732 + / -0.5 nm. The prepared ocimum gratissimum carbon dots can be applied to preparation of antibacterial drugs, especially drugs for inhibiting the activity of bacillus cereus and listeria, and the field of food preservation, and have the advantages of being wide in raw material source, simple in preparation method, low in cost, environmentally friendly and the like.

The invention discloses a high-performance sodium ion battery negative electrode ZnS / CoS (at) C composite material and a preparation method thereof, the material preparation method has the characteristics of definite control parameter, easy purity control, simple operation, good process repeatability and the like, and the prepared sodium ion secondary battery negative electrode material has excellent sodium ion intercalation and deintercalation capability and can be used for preparing a sodium ion secondary battery negative electrode material. The specific capacity, the cycling stability, the coulombic efficiency and the rate capability of the sodium ion secondary battery can be effectively improved, the requirements of different conditions can be met, and the application prospect is wide.

The invention discloses a mucosal epithelial cell targeted oral ROS response type nano-enzyme as well as a preparation method and application thereof, and relates to the technical field of biological medicines. The oral ROS response type nano-enzyme comprises Ce-CDs carbon dots and a betaine polymer, and the betaine polymer is coated on the surfaces of the Ce-CDs carbon dots to form nano-particles; the Ce-CCDs carbon dots are prepared by taking a metal cerium source and chlorogenic acid as raw materials through a pyrolysis method. Through structural innovation and function integration, the prepared nano-enzyme shows outstanding advantages in the aspects of catalytic activity, targeted delivery, collaborative treatment, industrial application and the like, a new technical scheme is provided for efficient and safe treatment of inflammatory bowel diseases, and the nano-enzyme has remarkable technical innovation and clinical application value.

A composite, comprising a binder, the binder comprising one or more of polymeric, metallic, or ceramic, or pyrolytic carbon binder and a nanostructured carbon having a cellular structure. The cellular structure comprises one or more cell walls having a structure formed by a template and one or more cavities. Each cavity is substantially enclosed by the one or more cell walls and substantially unimpregnated by a liquid or solid.

The invention discloses a silicon-based composite material, a negative pole piece and a secondary battery, and belongs to the technical field of batteries. According to the product, a core-shell structure is constructed by taking nano-sized silicon-carbon composite particles as an inner core and taking a derivative carbon nanosheet of an MOF material ZIF-90 with a nanosheet-shaped zinc imidazole skeleton as a shell, so that a good silicon element volume effect limiting effect can be realized, and the size stability of the product serving as a negative pole piece active material is guaranteed; meanwhile, the conductivity is high, the structural strength is good, high compaction density can be achieved, and a further prepared secondary battery can also have high rate performance while achieving high capacity and excellent cycle performance.

Disclosed are a nano silicon-carbon composite material, a preparation method therefor, and a use thereof. The nano silicon-carbon composite material comprises co-agglomerated nano silicon particles and nano carbon particles. The mass ratio of the nano silicon particles to the nano carbon particles is (45-60):(40-55). The nano silicon particles have an average particle size of 1-50 nm and a crystallite grain size of 1-10 nm. The nano silicon particles have varied crystal orientations and are freely combined with the nano carbon particles. In the nano silicon-carbon composite material, the nano silicon particles and the nano carbon particles are uniformly dispersed, and the particle size of the nano silicon particles is small. Moreover, due to the dispersion of the nano carbon, the phenomenon of agglomeration between the nano silicon particles can be reduced. When the composite material is applied to negative electrode materials and batteries, the phenomenon of electrochemical sintering can be effectively mitigated.

The invention relates to the technical field of agricultural application of nano materials, and discloses a preparation method and application of a photosynthetic accelerant containing carbon quantum dots. Urea and citric acid are adopted as raw materials, and the nitrogen-carbon molar ratio and hydrothermal reaction parameters are optimized, so that efficient doping of nitrogen and accurate regulation and control of the particle size are achieved, and the photosynthetic accelerant containing the carbon quantum dots is obtained. The nitrogen-doped carbon quantum dot photosynthetic promoter with excellent upconversion performance is successfully synthesized, the promoter has good water solubility and biocompatibility, the photosynthetic efficiency of plants can be greatly improved within the concentration range of 0-100 mg / L, a safe application window is defined, and by establishing foliage spraying and water planting dual-mode application specifications, the application range of the nitrogen-doped carbon quantum dot photosynthetic promoter is widened, and the application range of the nitrogen-doped carbon quantum dot photosynthetic promoter is widened. The problems that current crops are insufficient in solar spectrum utilization and low in light energy conversion efficiency are solved in a targeted manner by utilizing an ultraviolet light-photosynthetically active radiation conversion function mediated by the carbon quantum dots and combining the targeted enrichment permeation characteristic of the carbon quantum dots in chloroplast.

The invention discloses a lycium ruthenicum biomass carbon dot as well as a preparation method and application thereof. The novel lycium ruthenicum carbon dots are prepared by taking lycium ruthenicum as a raw material and adopting a one-step hydrothermal method, and the novel lycium ruthenicum carbon dots are used for detecting residual herbicides in soil without being interfered by other substances. The method for detecting the herbicide residues in the soil by adopting the prepared novel carbon dots is superior to a large instrument, the detection method has the advantages of simplicity in operation, low cost, high sensitivity and the like, the source of the lycium ruthenicum is wide, and the preparation process is green and environment-friendly. Therefore, the prepared carbon dots provide a new method for detection of the fine phosphinate ammonium salt, and a thought and a method are provided for specific application in agricultural production.

The invention relates to the technical field of pharmaceutical preparations, in particular to a preparation process of carbon dots for killing helicobacter pylori and application of the carbon dots in oral pharmaceutical preparations. The preparation method comprises the following steps: mixing microcrystalline cellulose and glycerol, freezing and crushing at an ultralow temperature, and selectively hydrolyzing by combining citric acid-malic acid mixed acid liquor to efficiently prepare a high-crystallinity cellulose nanocrystal template; the controllable synthesis of the carbon dots is realized by utilizing the hydrogen-bond interaction of hydroxyl / carboxyl on the surface of the cellulose nanocrystal and the nitrogen doping effect in the polymerization and carbonization process of citric acid and urea. Besides, when a sodium alginate-chitosan double-layer structure is constructed, carbon dots are introduced into the inner layer to endow the inner layer with special performance, a protein-polysaccharide network is formed on the outer layer through transglutaminase enzymatic crosslinking, and the oxidation resistance and mechanical strength are enhanced through secondary curing of tea polyphenol. According to the invention, food-grade raw materials are used for realizing high-efficiency antibiosis, the oral preparation safety specification is met, and the clinical transformation potential is realized.

The invention belongs to the technical field of hepatopathy treatment drugs, and particularly relates to an anti-inflammatory and anti-oxidative stress nano-enzyme Cu5.4O atCNDs with cascade enzyme activity and application of the nano-enzyme Cu5.4O atCNDs. The nano-enzyme Cu5.4O-coated CNDs is prepared by the following steps: dissolving CuCl2 in a carbon dot aqueous solution, reacting for 10-12 minutes at the temperature of 75-80 DEG C, then adding an L-ascorbic acid aqueous solution, regulating the pH value to 7.0-8.0 by using a NaOH solution, reacting for 10-12 hours at the temperature of 75-80 DEG C, after the reaction is finished, centrifuging to remove precipitates, dialyzing supernate, and freeze-drying to obtain the Cu5.4O-coated CNDs. Research results of the invention prove that the nano-enzyme Cu5.4O-coated CNDs has the potential of treating various acute liver injury diseases, and is an intervention strategy with a good clinical application prospect.

The invention relates to the technical field of mesoporous materials, and discloses an ordered mesoporous phenolic resin sphere, an ordered mesoporous carbon sphere and a preparation method and application thereof. The ordered mesoporous phenolic resin sphere has a uniform spherical morphology and a highly ordered mesoporous structure, the particle size of the ordered mesoporous phenolic resin sphere is 40-2000nm, and the aperture of the ordered mesoporous phenolic resin sphere is 3-10nm; the solid content reaches 100g / L. The preparation method comprises the following steps: dissolving a surfactant in a composite solvent, and uniformly stirring to obtain a precursor solution; dissolving a phenolic precursor and formaldehyde in the precursor solution, and slowly adding a pore-enlarging agent to obtain a uniform emulsion; adding a catalyst into the emulsion to carry out polymerization reaction; and after the reaction, collecting a solid phase, and carrying out heat treatment in an inert atmosphere to obtain the ordered mesoporous phenolic resin spheres. The ordered mesoporous phenolic resin spheres and the ordered mesoporous carbon spheres have uniform spherical structures, highly ordered mesoporous structures and high solid content; the preparation method is simple in process, high in expansibility and beneficial to large-scale production.

The invention relates to the technical field of traditional Chinese medicine carbon dots, in particular to ligusticum wallichii carbon dots, a medicine and application. The ligusticum wallichii carbon dots disclosed by the invention are obtained by carbonizing ligusticum wallichii by a hydrothermal method, wherein the hydrothermal method carbonization is a hydrothermal reaction at 175-195 DEG C for 8-12 hours; research finds that the ligusticum wallichii carbon dots have the characteristic of treating myocardial apoptosis caused by myocardial ischemia reperfusion injury, and compared with ligusticum wallichii carbon dots synthesized by ligustrazine and a pyrolysis method, the ligusticum wallichii carbon dots have the advantage that the heart function can be better recovered. The invention provides a new candidate drug for treating myocardial ischemia reperfusion injury.

The invention relates to the technical field of lithium ion batteries, and particularly discloses a silicon-carbon-based composite material, a preparation method and application of the silicon-carbon-based composite material in a lithium ion battery. Silicon-carbon particles with different silicon content distributions are obtained by controlling the deposition concentration of the silicon particles, a nonporous carbon layer and a silicon-carbon composite layer are sequentially deposited on the surfaces of the silicon-carbon particles, silicon in the silicon-carbon composite layer is etched to obtain a porous carbon layer, and finally the porous polymer composite solid electrolyte layer is coated. The non-porous carbon layer has a compact structure, can effectively inhibit the volume change of silicon particles in the charging and discharging process, and prevents the silicon particles from being broken and falling off in the circulation process; the porous carbon layer effectively increases the specific surface area of the material, and opens up more paths for lithium ion storage and transmission; the outermost porous polymer composite solid electrolyte layer can uniformly coat the silicon carbon particles, and the porous structure can improve the compatibility with the electrolyte, so that the high-temperature, fast-charging and cycling stability of the material is remarkably improved.

The invention relates to a method for preparing a hard carbon material from carbon dot heterogeneous cross-linked bituminous coal, a coal-based hard carbon material and application. The preparation method comprises the following steps: (1) soaking pretreated bituminous coal in an acid solution, washing to be neutral, and drying to obtain dry pulverized coal; (2) dispersing the carbon dots in an alcohol solvent for ultrasonic treatment to obtain a dispersion liquid; (3) mixing the dried pulverized coal obtained in the step (1) and the dispersion liquid obtained in the step (2), mechanically stirring, and drying to obtain a mixture; (4) performing low-temperature heating crosslinking on the mixture obtained in the step (3) in an oxygen-containing atmosphere so as to obtain a heterogeneous crosslinking product; and (5) performing high-temperature carbonization on the heterogeneous cross-linked product in an inert atmosphere to obtain the coal-based hard carbon material. The coal-based hard carbon material can be used as a sodium ion battery / potassium ion battery negative electrode, and has excellent sodium / potassium storage performance.

The invention discloses a preparation method of a doped and modified silicon-based negative electrode material, and aims to solve the problems of poor cycle performance and the like caused by large volume expansion and poor conductivity of the existing silicon-based negative electrode material. The method comprises the following steps: mixing nano silicon powder with a transition metal and alkaline earth metal composite doping source and a carbon source in a specific ratio, carrying out differential ball milling treatment twice, carrying out a gradient calcination process, and finally carrying out carbon nanotube coating in a fluidized bed by utilizing a chemical vapor deposition method. According to the invention, a conductive-buffer dual-function network is constructed through dual-metal synergistic doping, and a gradient heat treatment process is combined to optimize the crystallinity and pore structure of the material, so that the first coulombic efficiency of the prepared negative electrode material reaches 87% or more, the volume expansion rate is reduced to 150%, and the capacity retention rate exceeds 92% after 100 cycles; and the electrochemical performance and the structural stability of the silicon-based negative electrode material are remarkably improved.