70results about How to "Many defects" patented technology

The invention provides a multi-pot melt growth technique for growing sapphire crystals, comprising: (1) pretreating aluminum oxide raw material; (2) placing the pretreated aluminum oxide blocks and the oriented seed crystals into pots and moving into high temperature descending furnace, sealing the whole system and power-on to raise temperature, starting mechanical pump and diffusion pump in turn, vacuumizing to 10-3-10-4Pa, and when the furnace temperature up to 1500-1800deg.C, charging inert gas and continuing raising temperature to the set temperature (2100-2250deg.C); (3) when the furnace temperature up to the set temperature, preserving heat for 4-8 hours, regulating hearth temperature and pot positions to smelt raw material and seed crystal top to implement inoculation growth and setting solid-liquid interface temperature gradient at 10-50deg.C / cm and controlling pot descending rate at 0.1-3.0mm / h; and (4) after the crystal growth ends, making in-situ annealing treatment. And the process has features of raw material pretreatment, special temperature field design, multi-pot technique, in-situ annealing treatment, etc, and advantages of stable temperature field, adjustable temperature gradient, operating convenience, low average energy consumption, high yielding by one furnace, and beneficial to industrialized production.

The invention provides a preparation method for Portland cement with iron tailings. The Portland cement comprises at least the following raw materials in percentage by weight: 60-70% of calcium oxide, 12-20% of silicon oxide, 5-20% of the iron tailings and 3-6% of aluminium oxide. The preparation method comprises the following steps: weighing the raw materials according to the mass ratio, and mixing uniformly and fine grinding the weighed raw materials; calcining the fine grinded raw materials in a high-temperature furnace, and drawing out and quenching the calcined raw materials to obtain clinkers; adding the iron tailings to the clinkers, mixing uniformly mixtures of the iron tailings and the clinkers, and fine grinding the mixtures to obtain the Portland cement with the iron tailings, wherein the mass of the added iron tailings is 1-8% of the total mass of the clinkers. The method provided by the invention can effectively use the iron tailings as raw materials for production to prepare the Portland cement with excellent quality, so that the deficiencies in the prior art can be overcome, the use of the iron tailings can be maximized, and the purposes of saving resources, reducing the production cost, protecting environment and the like can be realized.

The invention discloses an adjustable table which is characterized in that four pull pipes are inserted into four upright table legs respectively; a transverse rod is fixed to the upper ends of the pull pipes of the two rear table legs, two hinged seats penetrate the transverse rod, and a base is fixed on the back surface of a table panel; the upper ends of the pull pipes of the two front table legs are fixed on the left side and right side of a table bucket, a supporting plate is fixed on the upper edge of the table bucket, and the front edge of the table panel is arranged on the supporting plate; both the table panel and the supporting plate can be lifted by pulling the pull pipes; the table panel slides back and forth on the supporting plate when the table panel or the supporting plate is separately lifted, so that the tilt degree of the table panel can be changed; oblique bracing plates at the lower ends of the pull pipes are used for positioning; the high ends of the bracing plates are propped against the inner walls of the pull pipes, and the low ends of the bracing plates are propped against the inner walls of the table legs; the low ends of the bracing plates are connected with the lower ends of connecting rods, connecting levers are connected to the upper ends of the connecting rods, and the low ends of the bracing plates are loosened downwards for lifting adjustment; after adjustment, the low ends of the bracing plates are pulled to ascend through the connecting levers to support the inner walls of the table legs again; due to the arrangement of the supporting plate, the defects of difficult operation and inconvenient fetching in the prior art are overcome; due to the arrangement of the connecting levers, the bolt screwing angle during adjustment is changed and the operation is convenient; besides, other defects are overcome.

A thermionic cathode (100) comprises an individual carbon nanotube (102) attached between two electrodes (104, 106). The electrodes (104, 106) each comprise a post (110, 112) and a carbon fibre (114, 116). A gap (118) narrower than the length of the nanotube (102) is provided between the two carbon fibres and the carbon nanotube (102) bridges the gap. This provides an extremely efficient thermionic cathode (100).

The invention provides hollow carbon nano-particles and a wave-absorbing material prepared therefrom. A preparation method of the hollow carbon nano-particles comprises the steps of mixing aniline, pyrrole, a non-ionic surface active agent and water to obtain a first solution; carrying out ice bath on an ammonium persulfate solution and adding the ammonium persulfate solution to the first solution to obtain a second solution; reacting the second solution, carrying out suction filtration, washing and freeze drying to obtain a head product; and carrying out carbonization treatment on the head product to obtain the hollow carbon nano-particles. A preparation method of the wave-absorbing material comprises the steps of adding graphene, the hollow carbon nano-particles and polypropylene to a torque rheometer for banburying to obtain a mixture; and carrying out hot pressing and cold pressing on the mixture to obtain the wave-absorbing material. By adopting the graphene and the hollow carbon nano-particles as wave-absorbing media and polypropylene as a carrier, the prepared wave-absorbing material can reach the effective absorption effect on an electromagnetic wave, and meanwhile, a series of advantages of low density and fatigue resistance of the polypropylene material are also integrated.

The invention discloses an optical film defect laser damage threshold test method. According to the method, after a laser beam passes through an attenuator and arrives at a beam splitter, and the laser beam in the transmission direction of the beam splitter passes through a focusing lens and arrives at a metal film; a CCD camera records a spot position where the laser irradiates on the surface ofthe metal film and a laser damage point coordinate where the laser irradiates on the surface of the optical film; and a scanning electron microscope records the longitudinal depth position of the defect damage point of the optical film in the irradiation of the laser and completes a defect damage point lateral energy density subdivision and longitudinal electric field normalization processing-combined analysis. In an optical film defect laser damage threshold test in the prior art, randomly-distributed defect damage points and laser energy density of Gaussian distribution in a laser spot are considered to be uniformly-distributed damage points and laser energy density equivalently, and influence on the defect damage point caused by the electric field distribution of the optical film is ignored, and as a result, many problems are brought about, while with the optical film defect laser damage threshold test method of the invention adopted, the above problems can be solved, and test accuracy can be improved.

Production of magnesium-base and hydrogen-storage alloy and composite material by laser sintering method is carried out by mixing elementary metal or hydrogen-storage alloy powders by ball mill, pressing mixed alloy biscuit, loading at 20-30MPa for 30 seconds, laser sintering by CO2 laser at 500-1600W, inducing into circulation water and cooling. The scanning speed ratio reaches to 100-120mm / min and diameter of light spot is 3-5mm. It's cheap, has less consumption, more yield and shorter sintering time, better performance.

A two component composition for making chemical mechanical polishing pad for polishing a semiconductor substrate is provided comprising a liquid aromatic isocyanate component having an unreacted isocyanate (NCO) concentration of from 15 to 40 wt. %, based on the total solids weight of the aromatic isocyanate component, such as methylene di(phenylisocyanate) (MDI), a liquid polyol component of a polyol having a polyether backbone and having from 5 to 7 hydroxyl groups per molecule, and a curative of one or more polyamine or diamine, wherein the reaction mixture comprises 50 to 65 wt. % of hard segment materials, based on the total weight of the to reaction mixture. The composition when mixed cured to form a polyurethane reaction product. Also provided are CMP polishing pads made from the polyurethane reaction product by spraying the composition into a mold.

The invention discloses a system for testing a defect laser-damaged threshold of an optical thin film, and the system comprises a laser, an attenuator, a beam splitter, an energy meter, a beam qualityanalyzer, a focusing lens, a CCD camera, a metal film, an optical thin film, a moving platform, a scanning electron microscope and a computer, wherein the laser, the attenuator, the beam splitter, the energy meter, the beam quality analyzer, the focusing lens, the CCD camera, the metal film, the optical thin film, the moving platform, the scanning electron microscope and the computer are sequentially placed according to an optical path. A laser beam emitted by the laser passes through the attenuator to reach the beam splitter. The laser beam in the transmission direction of the beam splitterpasses through the focusing lens to reach the metal film, and the CCD camera records the spot position of the laser irradiation on the surface of the metal film and the coordinates of the laser damagepoint when laser irradiation is on the surface of the optical thin film. The scanning electron microscope records the longitudinal depth position of the laser damage point of the optical thin film, and completes the combination analysis of the subdivision of the lateral energy density of the defect damage point and the normalization processing of a longitudinal electric field. The system can solve a problem caused by a condition that the peak energy density is taken as the defect damage density, thereby improving the testing precision.

The invention discloses a method for preparing Mg nano particles under a carbon source atmosphere. An Mg block is heated to evaporate through an electric arc under the mixed atmosphere of an inert gas and a carbon source gas, the Mg steam is separated from a heating area, nucleated and condensed to form Mg nano particles, and the Mg nano particles are passivated to form nano Mg particles in a particle diameter distribution range of 20 to 50 nanometers. The carbon source gas is decomposed under the action of arc plasma in the method, and the generated carbon is covered on the surface of the magnesium particles to inhibit the generation of magnesium oxide and inhibit the agglomeration of the magnesium particles, and meanwhile, the shape and the structure of the magnesium nano particles can be controlled by adjusting the content of the carbon source gas. The method is simple in equipment, high in synthesis speed and low in cost; and the prepared Mg nano particles have high purity and excellent mechanical property in hydrogen absorption and release when being used as a hydrogen storage material.

The invention belongs to the field of refractory materials, and mainly relates to a high-purity zirconia insulating refractory product. The high-purity zirconia insulating refractory product is composed of an aggregate and a matrix; the aggregate is porous zirconia particles prepared by a sintering method and having a volume density of 3.0-5.0 g / cm<3>; the aggregate accounts for 55%-80% of the total mass of the whole refractory product, and the aggregate has a particle size of 0.2-3 mm; the matrix comprises a mixture composed of zirconia fine powder and zirconia fine powder; the high-purity zirconia insulating refractory product is a refractory material having a certain shape at the normal temperature, and is subjected to heat treatment under a high temperature oxidizing atmosphere of which the maximum firing temperature is 1600-1800 DEG C. The high-purity zirconia insulating refractory product has the characteristics of high use temperature, moderate thermal conductivity and high mechanical strength, and has the functions of heat preservation and structural support at the high temperature.

The invention relates to a preparation method of a phosphorus-doped carbon-loaded molybdenum-tungsten carbide electrochemical hydrogen evolution catalyst, and belongs to the technical field of electrocatalytic materials. According to the invention, MoWCu multi-element metal-based MOF is used as a precursor, and then high-temperature heat treatment is carried out to obtain the catalyst; through nano confinement carbonization of an organic ligand and in-situ conversion of metal center ions, a component-controllable multi-element metal carbide / phosphorus-doped carbon nano composite structure is synthesized, so that an efficient electrochemical hydrogen evolution catalyst is created; the preparation method is simple in process, agglomeration of molybdenum-tungsten carbide nanoparticles is limited to a great extent, repeatability is good, and mass production is easy; and the catalyst shows good performance in an electro-catalytic hydrogen evolution reaction (HER) under an alkaline condition, and has a certain application prospect.

The invention discloses nitrogen-doped graphene for in-situ growth of a self-assembled denitration sulfur-resistant catalyst, and a preparation method thereof. The preparation method comprises the following steps: taking graphene oxide as a precursor, preparing modified nitrogen-doped graphene from 2,4,6-triaminopyrimidine and cyanuric acid, and growing a ternary Mn-Ce-SnOx catalyst on the surfaceof the modified nitrogen-doped graphene as a catalyst carrier in situ. The self-assembled ternary Mn-Ce-SnOx catalyst is uniformly and firmly loaded on the surface of the modified nitrogen-doped graphene in a surface in-situ growth manner, so that the obtained composite material has good sulfur resistance while having efficient denitration capability.

The invention provides a method for preparing a nano-structure of magnesium, which includes the following steps of: fully mixing MgO powder with C powder to make a block; then adopting an electric-arc heating method for evaporation to generate the nano-structure of magnesium; and selecting a variety of carbons to adjust the appearances of the nano-structure of magnesium. The method is simple in the device, high in resultant velocity, low in cost, and easy for realizing industrialized batch production. Products of the nano-structure of magnesium, which is obtained via the method, are less than 30 nanometers in dimension, with high purity and controllable appearances and structures. Besides, products of the nano-structure of magnesium have superb kinetic property for absorbing / desorbing hydrogen, with promising application prospects.

The invention relates to a nitrogen-doped carbon nanotube and a preparation method thereof. The method comprises the following steps: (a) mixing a carbon nanotube with alkali metal hydroxide or alkaline earth metal hydroxide according to a mass ratio of 1: 0.5 to 1: 3, then placing the obtained mixture in a reactor, introducing inert gas into the reactor so as to allow an inert atmosphere to be formed in the reactor, carrying out heating to 800 to 900 DEG C, then carrying out cooling to room temperature after a full reaction and cleaning and drying the obtained solid product so as to obtain a modified carbon nanotube; and (b) mixing the modified carbon nanotube with a nitrogen doping agent, successively carrying out full stirring and drying, placing the obtained mixture in the inert atmosphere, then carrying out heating to 800 to 900 DEG C, maintaining the temperature for 0.5 to 1 h, then carrying out cooling to room temperature and cleaning and drying the obtained solid product so as to obtain the nitrogen-doped carbon nanotube. According to the invention, the carbon nanotube activated by potassium hydroxide has a great number of defects and has high nitrogen content during nitrogen doping; and the preparation method has the advantages of low cost and easy realization of large-scale industrial production.

The invention relates to a defect-rich Fe2O3-FeF2 nano porous film, a preparation method and application thereof, and aims to solve the technical problems of complex preparation process, high reactiontemperature, long preparation cycle and high cost in existing hydrogen and oxygen evolution bifunctional electrocatalysts. The technical scheme adopted by the invention includes: firstly conducting anodic oxidation treatment on an ordinary iron foil, then using NH4F as the fluorine source, in an argon atmosphere, carrying out fluorination reaction on the iron foil subjected to anodic oxidation treatment by chemical vapor deposition (CVD) method, and performing natural cooling to room temperature, thus obtaining the Fe2O3-FeF2 nano porous film. According to the invention, the preparation process is simple, only needs anodic oxidation equipment and a CVD furnace, and can complete preparation of the Fe2O3-FeF2 composite nano porous film without special atmosphere and pressure environment, and the obtained Fe2O3-FeF2 nano porous film contains FeF2 and Fe2O3 phases, is rich in defects, and has the advantages of high electrocatalytic hydrogen and oxygen evolution activity, low initial potential, large electric current density, stable performance and the like.

The invention discloses a tin-manganese stannate-nitrogen carbon composite material with a hollow cubic structure as well as a preparation method and application thereof. The composite material is prepared by taking zinc hydroxystannate as a Sn source precursor, potassium permanganate as a Mn source precursor and dopamine as a nitrogen-doped carbon precursor through a multi-step hydrothermal method and a high-temperature carbonization method. The composite material is of a hollow cubic structure, and the cubic structure can provide enough space to buffer volume expansion during charging and discharging, so the pulverization of an electrode is prevented. Meanwhile, the carbon layer wrapped on the outer layer of the composite material relieves the stress of the volume change of the electrode on one hand, and improves the conductivity of the material on the other hand. Particularly, nitrogen atoms are doped, so that the carbon material has more defects, the conductivity of electrons / ions is improved, the transmission of the electrons / ions is accelerated, and the specific capacity and the cycle performance of the material are improved.

The invention relates to a lithium iron phosphate material, and a preparation method and application thereof. The preparation method comprises the following steps: (1) dispersing a lithium source, aniron source, a phosphorus source, a template and a chelating agent in water to prepare a raw material mixed solution, wherein the template can generate bubbles in the water; and (2) carrying out a hydrothermal reaction on the raw material mixed solution under a preset pressure to obtain a pre-product. The template and the chelating agent are added into the raw material mixed solution, the templatecan generate bubbles in water to form vacuole films, further, lithium iron phosphate crystals in the raw material mixed solution are promoted to directionally grow along gaps among the vacuole films,the chelating agent can make the vacuole films stably exist in the reaction system under the predetermined pressure, and the size of the vacuole films is controlled by adjusting the pressure of the system so as to stably control the pore size and the morphology of the lithium iron phosphate.

The invention discloses a method for preparing Mg nano particles under a carbon source atmosphere. An Mg block is heated to evaporate through an electric arc under the mixed atmosphere of an inert gas and a carbon source gas, the Mg steam is separated from a heating area, nucleated and condensed to form Mg nano particles, and the Mg nano particles are passivated to form nano Mg particles in a particle diameter distribution range of 20 to 50 nanometers. The carbon source gas is decomposed under the action of arc plasma in the method, and the generated carbon is covered on the surface of the magnesium particles to inhibit the generation of magnesium oxide and inhibit the agglomeration of the magnesium particles, and meanwhile, the shape and the structure of the magnesium nano particles can be controlled by adjusting the content of the carbon source gas. The method is simple in equipment, high in synthesis speed and low in cost; and the prepared Mg nano particles have high purity and excellent mechanical property in hydrogen absorption and release when being used as a hydrogen storage material.

The invention relates to a preparation method of the phosphorus residue portland clinker. The clinker is includes limestone, pyrite residue, river sand, phosphorus reside and gangue raw material. It is formed by the following steps that the raw material is mixed in proportion, used pulverizing together and fired by the pre-decomposition kiln system at the condition of new type dry method cement system. The weight mixing proportion of the raw material orderly is from seventy to eighty five, from five to seven, from one point five to three, from eight to fifteen, and from zero point five to five. The invention can use the industry waste that phosphorus reside, pyrite residue and gangue as the raw material to prepare the low temperature loading type portland clinker. So it can solve the shortage of the fat limestone, clay, and iron ore, as well as supply a perfect approach for industry waste processing. Moreover, it can save the resource and energy source, reduce the pollution discharging, and is good for reducing cost, protecting environment, and increasing output and quality of the clinker, so that it is easy to popularly use in the new type dry method cement plant.

The invention relates to a method for preparing a polycrystalline ultra-thin metal film and two-dimensional nano pattern. The method comprises a step of preparing a two-dimensional array structure formed by units with special morphology by using UV photolithographic process, and forming a polymer mask, a step of realizing the dense self-assembly of a monodisperse silver nano plate at a substrate through an ascorbic acid AA modified high yield silver nano plate solution, a step of removing the polymer mask through a developer, and forming a patterned self-assembled silver nano plate array on the substrate, a step of removing a silver nano plate coating on the substrate through a physical or chemical method, and a step of forming a (quasi) continuous polycrystalline ultra-thin metal film and two-dimensional nano pattern through continued growth. According to the method, the large-scale preparation of special plane structure sub wavelength devices is realized, the key problem of large area metal thin film optoelectronic device application is solved, the loss of the device is reduced greatly, the performance of the device is improved, the preparation of an ultra-thin continued metal film with the minimum of 10 nm is realized, and the method is a breakthrough of existing preparation technology.

The invention relates to a method for preparing a metal / metal oxide composite electrocatalyst. The method comprises the following steps: (a), growing a metal oxide on a conductive carrier; (b), assembling the metal oxide used as a working electrode, a lithium sheet used as a counter electrode and electrolyte to form a lithium ion half cell; circularly charging and discharging until the dischargingstate is the final state; (c), taking out a product processed by the step (b), washing, and drying. According to the method, lithium ion induced phase transformation reaction is carried out to transform the metal oxide into a metal phase, so that the obtained metal / metal oxide composite material is rich in interface, few in defects and outstanding in conductivity; when the metal / metal oxide composite material is treated as an electrolyzing water catalyst, the catalyzing activity bit density is greatly increased; the substance transferring in the electro-catalysis reaction is speed up, and thus the catalyzing activity is outstanding. The method is generally suitable for a plurality of metal oxides; compared with an existing composite metal oxide synthesizing method, the method is simple, easy to carry out, low in price, high in efficiency, high in controllability, and high in repeatability.

The invention relates to a nitrogen-doped carbon nanotube and a preparation method thereof. The method comprises the following steps: placing a carbon nanotube in a reactor with plasma for 1 to 2 h so as to obtain a modified carbon nanotube; mixing the modified carbon nanotube with a nitrogen doping agent, successively carrying out full stirring and drying, then introducing inert gas into the reactor so as to allow an inert atmosphere to be formed in the reactor, then carrying out heating to 800 to 900 DEG C, maintaining the temperature for 0.5 to 1 h and carrying out cooling to room temperature after a reaction; and cleaning and drying the obtained solid product so as to obtain the nitrogen-doped carbon nanotube. According to the invention, the carbon nanotube treated by plasma has a great number of defects and has high nitrogen content during nitrogen doping; and the preparation method has the advantages of low cost and easy realization of large-scale industrial production.

The invention relates to a railway vehicle air resistance calculation method based on numerical simulation. The method comprises the steps that a model needed by numerical simulation is established, and grids are divided; analogue simulation is performed, the air resistance coefficient of the vehicle is corrected according to the air pressure difference resistance and the air friction resistance of the rail vehicle; and according to the corrected vehicle air resistance coefficient, a vehicle air resistance rapid calculation formula is constructed and the vehicle air resistance rapid calculation formula is verified. According to the method, numerical simulation calculation is carried out on the numerical value of the air resistance borne by a common rail vehicle model moving under typical working conditions, calculation of the middle vehicle differential pressure resistance, the tail vehicle differential pressure resistance and the whole vehicle air friction resistance is added, and thevehicle air resistance coefficient is corrected. Defects in an existing air resistance calculation formula are overcome, and the accuracy of the air resistance calculation formula is improved, so that the air resistance calculation formula is suitable for vehicles with large slenderness ratios, such as railway vehicles.

A two component composition for making chemical mechanical polishing pad for polishing a semiconductor substrate is provided comprising a liquid aromatic isocyanate component having an unreacted isocyanate (NCO) concentration of from 15 to 40 wt. %, based on the total solids weight of the aromatic isocyanate component, such as methylene di(phenylisocyanate) (MDI), a liquid polyol component of a polyol having a polyether backbone and having from 5 to 7 hydroxyl groups per molecule, and a curative of one or more polyamine or diamine, wherein the reaction mixture comprises 50 to 65 wt. % of hard segment materials, based on the total weight of the reaction mixture. The composition when mixed cured to form a polyurethane reaction product. Also provided are CMP polishing pads made from the polyurethane reaction product by spraying the composition into a mold.

The invention discloses a wide-spectral-response soft bismuth ore-based efficient photocatalyst and a preparation method thereof, and belongs to the field of environmental science and inorganic material preparation. The novel broad-spectrum-response soft bismuth ore-based photocatalyst Bi[24](Bi[2-x]Co[x])O[39+x] (x is greater than 0 and less than or equal to 1) for efficient photocatalytic degradation of organic pollutants is prepared by adopting a hydrothermal method, specifically, bismuth salt and cobalt salt are dissolved in alkali liquor with a specific concentration, and hydrothermal reaction is carried out at a relatively mild temperature for a relatively long time, so that the photocatalyst Bi[24](Bi[2-x]Co[x])O[39+x] is prepared. The preparation method provided by the invention islow in cost, simple in process and easy to control, and provides a new preparation idea for preparation of other soft bismuth ore photocatalysts with similar structures; the obtained catalyst has thecharacteristics of narrow energy gap, good crystallinity and high purity, shows good visible light catalytic degradation activity on organic pollutants in water such as dyes, phenols and the like, and has a wide potential application prospect in the field of visible light organic pollutant degradation.

The invention provides a high-activity cementing material based on engineering residue soil, and the material is prepared from the following raw materials in parts by mass: 70 to 80 parts of engineering residue soil, 5 to 10 parts of siliceous tailings, 5 to 10 parts of fly ash and 10 to 15 parts of kiln dust, the preparation method comprises the following steps: (1) mixing the engineering residue soil, the siliceous tailings and the fly ash, and grinding to obtain mixed powder; (2) putting the mixed powder and kiln dust into a calcining container, and performing calcining in a calcining kiln at 700-800 DEG C for 2-3 hours; (3) grinding the calcined product into powder to obtain the high-activity cementing material. The materials of the high-activity cementing material are simple and easy to obtain, resource utilization of the engineering residue soil and the siliceous tailings is achieved, the production cost is low, meanwhile, the cementing material has high cementing activity through thermal and chemical excitation dual treatment, and the early-stage activity of concrete can be remarkably improved.

The invention relates to a novel lithium ion secondary battery positive electrode material--NbOx (wherein x is equal to 1 to 2). A lithium ion secondary battery with the positive electrode material containing the active substance NbOx and a negative electrode prepared from a lithium sheet is characterized in that charge and discharge voltage platforms of the lithium ion secondary battery are 1.8 v and 1.6 V, respectively, and the lithium ion secondary battery has good charge-discharge cycle performance, environment friendliness, no pollution, etc. NbOx (wherein x is equal to 1 to 2) is a novel lithium ion battery positive electrode material with application prospects, high capacity and high safety.

The invention discloses a CoS-SnS-NC composite material with a heterojunction structure as well as a preparation method and application thereof. The CoS / SnS heterojunction structure is taken as a core of the composite material, and a nitrogen-doped carbon layer is taken as a shell of the composite material; an internal electric field can be introduced by the heterojunction structure, so that the electron conductivity and the ion diffusion kinetics are improved, and the transmission of electrons and ions is further facilitated; and the composite material is of a spherical structure, and the particle size is 0.8-1.2 [mu] m. The composite material has a spherical micro / nano structure, and the micro / nano structure can shorten the diffusion distance of sodium ions and provide more sodium storage active sites. The preparation method comprises the following steps: S1, taking cobalt nitrate, urea and ammonium fluoride as raw materials, and synthesizing a Co precursor through a hydrothermal method; s2, carrying out solvothermal reaction on the Co precursor, thioacetamide and tin tetrachloride to obtain Co3S4@ SnS2; s3, coating the prepared sample with a polydopamine layer, and forming Co3S4 @SnS2-PDA; and S4, carrying out high-temperature reaction under the protection of Ar, so as to obtain CoS-SnS-NC.