WO2023245986A1 - Core-shell structure micron silicon-carbon composite material and preparation method therefor, electrode, and battery - Google Patents

Core-shell structure micron silicon-carbon composite material and preparation method therefor, electrode, and battery Download PDF

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WO2023245986A1
WO2023245986A1 PCT/CN2022/135031 CN2022135031W WO2023245986A1 WO 2023245986 A1 WO2023245986 A1 WO 2023245986A1 CN 2022135031 W CN2022135031 W CN 2022135031W WO 2023245986 A1 WO2023245986 A1 WO 2023245986A1
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micron silicon
carbon
core
silicon
shell structure
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PCT/CN2022/135031
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French (fr)
Chinese (zh)
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王胜彬
王世贤
杨琪
俞会根
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北京卫蓝新能源科技有限公司
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of lithium batteries, and specifically relates to a core-shell structure micron silicon-carbon composite material and a preparation method thereof, electrodes and batteries including the core-shell structure micron silicon-carbon composite material.
  • Nanostructured silicon can alleviate the breakage of silicon particles to a certain extent and has become an important direction of current research.
  • the disadvantages of nano-silicon are high cost, poor batch stability, high activity, easy to oxidize, easy to agglomerate, and difficult to disperse, which makes its preparation difficult and poor consistency.
  • Micron silicon can solve the above problems, and it has gradually attracted attention due to its low cost, simple preparation process and high first efficiency.
  • micron silicon compared with nano-silicon, micron silicon has a more severe volume expansion effect and poorer electronic conductivity, resulting in a rapid decline in its cycle performance.
  • General core-shell structures are also difficult to withstand the volume expansion of silicon.
  • this application aims to provide a core-shell structure micron silicon-carbon composite material and a preparation method of a core-shell structure micron silicon-carbon composite material, which can effectively improve improve the cycle performance and Coulombic efficiency of the battery.
  • a core-shell structure micron silicon carbon composite material characterized in that it includes:
  • a carbon shell layer covering the core wherein the carbon shell layer includes a dense carbon layer one, a porous carbon layer and a dense carbon layer two from the inside to the outside.
  • the core-shell structure micron silicon-carbon composite material according to item 1 characterized in that the average particle size D50 of the micron silicon is 1 to 8 ⁇ m, and the sphericity is 0.3 to 0.95.
  • the porosity of the dense carbon layer 1 is 10% to 50%, preferably 10% to 30%.
  • the core-shell structure micron silicon carbon composite material according to any one of items 1 to 3, characterized in that the thickness of the porous carbon layer is 5% to 25% of the average particle diameter D50 of the micron silicon, Preferably, it is 10% to 20%;
  • the pores of the porous carbon layer are formed by a pore-forming agent and an etchant, and the pore-forming agent is selected from the group consisting of nano zinc oxide, nano magnesium oxide, nano aluminum oxide, nano silicon oxide, nano copper oxide, and nano iron oxide. and one or more types of nanomanganese oxide;
  • the average particle size D50 of the pore-forming agent is 50 to 500 nm, preferably 50 to 200 nm;
  • the average pore diameter of the pores is not less than the average particle diameter D50 of the pore-forming agent
  • the etchant is selected from one, two or three types of hydrochloric acid, nitric acid and hydrofluoric acid.
  • the core-shell structure micron silicon-carbon composite material according to any one of items 1 to 4, characterized in that the thickness of the second dense carbon layer is 0.05% to 1% of the average particle diameter D50 of the micron silicon. , preferably 0.1% to 0.2%;
  • the porosity of the second dense carbon layer is 5% to 30%, preferably 5% to 25%.
  • the core-shell structure micron silicon-carbon composite material according to any one of items 1 to 5, characterized in that the Shore hardness of the carbon shell layer is 10-50HSD, preferably 25-40HSD.
  • the core-shell structure micron silicon carbon composite material according to any one of items 1 to 6, characterized in that the carbon source of the dense carbon layer one is selected from the group consisting of asphalt, phenolic resin, humic acid, and tannic acid. , one or more of polymerized dopamine, polypyrrole, methane and ethane; or,
  • the carbon source of the porous carbon layer is selected from one or more of asphalt, phenolic resin, humic acid, tannic acid, polymerized dopamine, polypyrrole, methane and ethane; or,
  • the carbon source of the dense carbon layer 2 is selected from one or more of asphalt, phenolic resin, humic acid, tannic acid, polymerized dopamine, polypyrrole, methane and ethane.
  • the core-shell structure micron silicon carbon composite material according to any one of items 1 to 7, characterized in that the core-shell structure micron silicon carbon composite material has a true density of 1.2 to 2.1 g/cc, preferably 1.4 ⁇ 1.8g/cc.
  • a method for preparing core-shell structure micron silicon-carbon composite material characterized in that it includes the following steps:
  • the composite particle two is sintered in an inert atmosphere and dispersed in an etchant to obtain a composite particle three including micron silicon, a dense carbon layer one and a porous carbon layer;
  • the composite particle three is coated with carbon source three and sintered to obtain a core-shell structure micron silicon-carbon composite material including micron silicon, dense carbon layer one, porous carbon layer and dense carbon layer two.
  • the preparation method according to item 9 or 10 characterized in that the sintering temperature for coating the composite particles three with carbon source three and then sintering is 600 to 1100°C, preferably 700 to 1000°C, preferably The sintering time for coating the composite particles three using carbon source three and then sintering is 2 to 6 hours.
  • the preparation method according to item 10 characterized in that the sintering temperature after coating the composite particles one with a carbon source two and a pore-forming agent is 700 to 1000°C, preferably 800 to 900°C. , it is preferable that the sintering time for coating the composite particles one with the carbon source two and the pore-forming agent and then sintering is 1 to 3 hours.
  • a core-shell structure micron silicon-carbon composite material prepared by the preparation method described in any one of items 9 to 13.
  • micron silicon has an average particle size D50 of 1 to 8 ⁇ m and a sphericity of 0.3 to 0.8.
  • micron silicon is spherical micron Silicon, the interior of which is crystalline silicon and the surface is amorphous silicon.
  • the average particle size D50 of the spherical micron silicon is 1 to 8 ⁇ m, and the sphericity is 0.7 to 0.95;
  • the average particle size D50 of the spherical micron silicon is 2 to 5 ⁇ m;
  • the sphericity of the spherical micron silicon is 0.8 to 0.95;
  • the specific surface area of the spherical micron silicon is 0.5 to 5 m 2 /g, preferably 1 to 4 m 2 /g;
  • the thickness of the amorphous silicon is 1 to 20 nm, preferably 2 to 10 nm.
  • An electrode characterized in that it includes an electrode current collector and an electrode active material layer coated on the surface of the electrode current collector, and the electrode active material layer includes any one of items 1 to 8 and 14.
  • the electrode is a negative electrode.
  • a battery characterized in that it includes a positive electrode, a negative electrode, a separator and an electrolyte, wherein the negative electrode is the negative electrode described in item 17.
  • micron silicon-dense carbon layer one-porous carbon layer-dense carbon layer two.
  • Each carbon layer is organically connected and does not exist as a separate component.
  • the dense carbon layer tightly covers the micron silicon, providing inward pressure during circulation, maintaining physical contact between the small particles produced after the micron silicon particles are broken, and at the same time serving as an expansion force transmission medium to transfer stress to the porous carbon layer for absorption ; And avoid direct contact between silicon and the cavities in the porous carbon layer to prevent the fine particles after broken silicon from falling into the cavities and losing electrochemical activity.
  • the porous carbon layer has numerous cavities, which provide reversible compression space and space for the expansion of silicon.
  • the reverse effect of stress is used to compress the dense carbon layer during the delithiation state, so that the dense carbon layer will be released after the electrochemical process.
  • the broken micron silicon particles are tightly packed to maintain ion/electron channels.
  • the dense carbon layer 2 serves as a strong coating layer to maintain the structural integrity and mechanical stability of the porous carbon layer when it is subjected to micron silicon expansion stress.
  • the dense carbon layer 2 is combined with the porous carbon layer to effectively absorb and release the expansion stress.
  • the dense carbon layer isolates the infiltration of electrolyte and avoids side reactions between the many active sites of the porous carbon layer and the electrolyte, thereby improving cycle performance and Coulombic efficiency.
  • the porous carbon layer of the core-shell structure micron silicon-carbon composite material of this application has carbon pillars connecting the dense carbon layer one and the dense carbon layer two.
  • the carbon pillars play the role of conducting ions and electrons during the electrochemical process. Avoid the existence of cavity layers in the core-shell structure from blocking the conduction of isolators and electrons.
  • the core-shell structure micron silicon-carbon composite material of this application can not only alleviate the volume expansion of micron silicon and maintain particle stability; it can also provide an inward pressure for the broken particles after circulation, maintaining the physical properties of the primary particles after being broken. Contact to maintain electron and ion diffusion paths and improve cycle performance.
  • Figure 1 is a schematic structural diagram of a micron silicon-carbon composite material with a core-shell structure according to a specific embodiment of the present application.
  • Figure 2 is a TEM image of spherical micron silicon according to a specific embodiment of the present application.
  • this application provides a core-shell structure micron silicon carbon composite material, which includes:
  • a carbon shell layer covering the core wherein the carbon shell layer includes a dense carbon layer one, a porous carbon layer and a dense carbon layer two from the inside to the outside.
  • the core-shell structure micron silicon-carbon composite material of the present application constructs the cavity in the carbon coating layer, which avoids the obstacles in ion and electron conduction caused by the direct contact between the cavity and silicon.
  • the internal dense carbon layer wraps the micron silicon, and the coating forms inward pressure during circulation, ensuring that the particles after the micron silicon is broken still maintain physical contact and maintain electronic and ion conductivity.
  • the dense carbon layer 2 on the surface is combined with the porous carbon layer inside to jointly absorb and release expansion stress. At the same time, the dense carbon layer isolates the infiltration of electrolyte and avoids side reactions between the many active sites of the porous carbon layer and the electrolyte, thereby improving cycle performance and Coulombic efficiency.
  • Inside-out in this application refers to the direction from the core to the carbon shell.
  • the core-shell structure micron silicon-carbon composite material is composed of: a core formed of micron silicon 1 and a carbon shell layer covering the core, wherein the carbon
  • the shell layer includes a dense carbon layer 2, a porous carbon layer 3 and a dense carbon layer 2 4 from the inside to the outside.
  • the average particle size D50 of the micron silicon of the present application is 1 to 8 ⁇ m, for example, it can be 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 3 ⁇ m, 3.5 ⁇ m, 4 ⁇ m, 4.5 ⁇ m, 5 ⁇ m, 5.5 ⁇ m, 6 ⁇ m, 6.5 ⁇ m, 7 ⁇ m, 7.5 ⁇ m, 8 ⁇ m, etc.
  • the sphericity is 0.3 ⁇ 0.95, for example, it can be 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43 ⁇ 0.44 ⁇ 0.45 ⁇ 0.45 ⁇ 0.46 ⁇ 0.47 ⁇ 0.48 ⁇ 0.49 ⁇ 0.5 ⁇ 0.51 ⁇ 0.52 ⁇ 0.53 ⁇ 0.54 ⁇ 0.55 ⁇ 0.56 ⁇ 0.57 ⁇ 0.58 ⁇ 0.59 ⁇ 0.6 ⁇ 0.61 ⁇ 0.62 ⁇ 0.63 ⁇ 0.64 ⁇ 0.65 ⁇ 0.66 ⁇ 0.67 , 0.68, 0.69,
  • the “average particle size D50” in this application refers to the particle size corresponding to when the cumulative particle size distribution number of a sample reaches 50%. Its physical meaning is that particles with a particle size smaller than it account for 50% of the total. Particle size distribution can be detected using conventional instruments used by those skilled in the art, such as using a laser particle size analyzer.
  • the “sphericity” used in this application is a parameter that characterizes the morphology of particles. The closer a particle is to a sphere in shape, the closer its sphericity is to 1.
  • the ratio of the surface area of a sphere with the same volume as the object to the surface area of the object is sphericity.
  • the sphericity of the ball is equal to 1, and the sphericity of other objects is less than 1.
  • the sphericity formula of any particle is: Among them, ⁇ is the particle sphericity, Vp is the particle volume, and Sp is the particle surface area.
  • the sphericity of the present application can be detected, for example, by the specific methods given in the examples, and measured using a dynamic image particle analyzer.
  • the thickness of the dense carbon layer I is 0.05% to 1% of the average particle size D50 of micron silicon, for example, it can be 0.05%, 0.07%, 0.09%, 0.1%, 0.1%, 0.15 %, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, etc., preferably 0.1% to 0.4%.
  • the dense carbon layer wraps the micron silicon. During circulation, the coating layer forms inward pressure to ensure that the particles after the micron silicon is broken still maintain physical contact and maintain electronic and ion conductivity.
  • the thickness of the dense carbon layer is too small, it will not be able to withstand it. Micron silicon expands and transfers its expansion stress to the porous carbon layer, resulting in the failure of the cladding layer structure and a decrease in the electrochemical performance of the material; if the thickness of the dense carbon layer is too large, the electronic conductive channels are affected, and at the same time the material's electrochemical properties are affected. Specific capacity and first effect.
  • the thickness of the dense carbon layer 1 of the present application can be obtained by measuring multiple points through a transmission electron microscope and taking the average value.
  • it can be 2 points, 3 points, 4 points, 5 points, 6 points, 7 points, 8 points. points, 9 points, 10 points, etc.
  • the porosity of the dense carbon layer one is 10% to 50%, for example, it can be 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, etc., preferably 10% to 30%.
  • the dense carbon layer needs to transfer the expansion force of micron silicon to the porous carbon layer, and it bears a very huge force in this process.
  • the smaller porosity in this application can reduce defects in the carbon layer structure and improve the yield of the material. strength.
  • the porosity of the dense carbon layer 1 of the present application can be measured, for example, by a true density tester.
  • the thickness of the porous carbon layer is 5% to 25% of the average particle diameter D50 of micron silicon, for example, it can be 5%, 6%, 7%, 8%, 9%, 10% , 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, etc., preferably 10 % ⁇ 20%.
  • the thickness of the porous carbon layer of the present application can be obtained by measuring multiple points through a transmission electron microscope and taking the average, for example, it can be 2 points, 3 points, 4 points, 5 points, 6 points, 7 points, or 8 points. points, 9 points, 10 points, etc.
  • the pores of the porous carbon layer are formed by a pore-forming agent and an etchant.
  • the pore-forming agent is added and mixed with the carbon source, and then an etchant that can react with the pore-forming agent is added to form the said pore-forming agent.
  • Porous, reaction products of pore formers and etchants as well as excess etchant can be removed by cleaning and subsequent sintering steps.
  • the pore-forming agent can be selected from one or more of nano zinc oxide, nano magnesium oxide, nano aluminum oxide, nano silicon oxide, nano copper oxide, nano iron oxide and nano manganese oxide; the etchant can be Select one, two or three types from hydrochloric acid, nitric acid and hydrofluoric acid.
  • the average particle size D50 of the pore-forming agent is 50 to 500nm, for example, it can be 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, etc., preferably 50 to 500nm. 200nm.
  • the average pore size of the porous carbon layer is not less than the average particle size D50 of the pore-forming agent.
  • the average pore size of the present application can be measured by gas permeation method.
  • the thickness of the second dense carbon layer is 0.05% to 1% of the average particle diameter D50 of micron silicon, for example, it can be 0.05%, 0.07%, 0.09%, 0.1%, 0.1%, 0.15 %, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, etc., preferably 0.1% to 0.2%.
  • the second dense carbon layer is coated on the porous carbon layer, which plays the role of closing the porous carbon layer and isolating the electrolyte.
  • the thickness of the dense carbon layer 2 of the present application can be obtained by measuring multiple points through a transmission electron microscope and taking the average value. For example, it can be 2 points, 3 points, 4 points, 5 points, 6 points, 7 points, 8 points. points, 9 points, 10 points, etc.
  • the porosity of the second dense carbon layer is 5% to 30%, for example, it can be 5%, 7%, 9%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, etc., preferably 5% to 25%.
  • the second dense carbon layer cooperates with the two inner coating layers to alleviate the expansion of micron silicon. It will be affected by the expansion of micron silicon during the cycle. If the porosity is too high, the structure will There are many defects, and the yield strength of the structure decreases, which will cause the structure to be destroyed during the cycle; at the same time, the dense carbon layer 2 also plays a role in isolating the electrolyte. Excessive porosity will lead to the penetration of the electrolyte, thereby reducing the electrochemical performance of the material. .
  • the porosity of the dense carbon layer 2 of the present application can be measured, for example, by a true density tester.
  • the Shore hardness of the carbon shell layer is 10-50HSD, for example, it can be 20HSD, 25HSD, 30HSD, 35HSD, 40HSD, 45HSD, etc., preferably 25-40.
  • the Shore hardness of the carbon shell layer in this application refers to the Shore hardness of the carbon shell layer including dense carbon layer one, porous carbon layer and dense carbon layer two.
  • “Shore hardness” in this application refers to a method of testing and expressing the hardness of materials. It is measured using a Shore hardness tester. For example, the material can be mixed with a binder and then pressed into tablets. The pressure is the limit when the particles are not broken.
  • the maximum pressure it can withstand can be observed and adjusted with SEM), and then measured using this piece.
  • the Shore hardness that is too small cannot maintain the structure of the coating layer itself and the stress generated by silicon expansion. Only an appropriate Shore hardness can be maintained. Its own structure is stable and its digestion volume expands.
  • the true density of the core-shell structure micron silicon carbon composite material is 1.2-2.1g/cc, for example, it can be 1.2g/cc, 1.3g/cc, 1.4g/cc, 1.5g/cc , 1.6g/cc, 1.7g/cc, 1.8g/cc, 1.9g/cc, 2.0g/cc, 2.1g/cc, etc., preferably 1.4 to 1.8g/cc.
  • the “true density” in this application refers to the actual mass of solid matter per unit volume of the material in an absolutely dense state, that is, the density after removing internal pores or gaps between particles. The true density of this application is measured using a powder true density tester.
  • the sample can be placed in the true density tester, using helium as the medium, gradually pressurizing the measuring chamber to a specified value, and then the helium expands into the expansion chamber.
  • the equilibrium pressure of the two processes is automatically recorded by the instrument. According to the law of conservation of mass, after calibrating the volumes of the measurement chamber and the expansion chamber through the standard ball, the volume of the sample is determined and the true density is calculated.
  • the mass ratio of the carbon shell to the core is 0.16-0.5:1, preferably 0.22-0.36:1, for example, it can be 0.16:1, 0.18:1, 0.2:1, 0.22:1 , 0.28:1, 0.3:1, 0.32:1, 0.36:1, 0.38:1, 0.4:1, 0.42:1, 0.46:1, 0.48:1, 0.5:1, etc.
  • the carbon sources of the first dense carbon layer, the porous carbon layer and the second dense carbon layer may be exactly the same, may be completely different, or may not be exactly the same.
  • the carbon source in this application is not limited and can be any carbon source.
  • the carbon source of each layer can be selected from one of asphalt, phenolic resin, humic acid, tannic acid, polymerized dopamine, polypyrrole, methane and ethane. Or two or more, preferably one or two or more selected from the group consisting of asphalt, phenolic resin and humic acid.
  • the carbon source of the dense carbon layer I is selected from one or more of asphalt, phenolic resin and humic acid; and/or the carbon source of the porous carbon layer is selected from asphalt. , one or more of phenolic resin and humic acid; and/or the carbon source of the dense carbon layer 2 is selected from one or more of asphalt, phenolic resin and humic acid.
  • this application also provides a method for preparing a core-shell structure micron silicon-carbon composite material, which includes the following steps:
  • the composite particle three is coated with carbon source three and sintered to obtain a core-shell structure micron silicon-carbon composite material including micron silicon, dense carbon layer one, porous carbon layer and dense carbon layer two.
  • the preparation method of the core-shell structure micron silicon carbon composite material of the present application includes the following steps:
  • the composite particle three is coated with carbon source three and sintered to obtain a core-shell structure micron silicon-carbon composite material including micron silicon, dense carbon layer one, porous carbon layer and dense carbon layer two.
  • This application does not specifically limit the etching time of the etchant, as long as the etchant is excessive.
  • the sintering temperature for coating micron silicon with the second carbon source and then sintering is 700 to 1000°C, for example, it can be 700°C, 720°C, 740°C, 760°C, 780°C, 800°C, 820°C, 840°C, 860°C, 880°C, 900°C, 920°C, 940°C, 960°C, 980°C, 1000°C, etc., preferably 800 ⁇ 900°C, preferably using carbon Source 2 coats the micron silicon and then sinters the sintering time for 1 to 3 hours.
  • the sintering temperature for coating the composite particles three with carbon source three and then sintering is 600 to 1100°C, for example, it can be 600°C, 620°C, 640°C, 660°C, 680°C, 700°C, 720°C, 740°C, 760°C, 780°C, 800°C, 820°C, 840°C, 860°C, 880°C, 900°C, 920°C, 940°C, 960°C, 980°C, 1000°C, 1020°C , 1040°C, 1060°C, 1080°C, 1100°C, etc., preferably 700 to 1000°C, and the sintering time for coating the composite particles three with carbon source three and then sintering is preferably 2 to 6 hours.
  • the sintering device in this application. Any device that can pass into the atmosphere and heat up the sintering can be used.
  • it can be a dry rotary kiln, an electric furnace, a tube furnace, a box furnace, a roller kiln, etc.
  • it can be used Oxygen-acetylene flame, oxygen-hydrogen flame, etc. sintering.
  • the sintering of the present application is performed under an inert gas.
  • the inert atmosphere of the present application is not limited and can be any inert atmosphere, such as nitrogen or argon.
  • the coating is solid phase coating.
  • a mechanical fusion machine can be used for solid phase coating.
  • both the porous carbon layer and the dense carbon layer are solid phase coatings, and the dense carbon layer one can be solid phase coating, gas phase coating, or liquid phase coating.
  • the dense carbon layer The first carbon layer is solid phase coating.
  • the sintering includes cooling.
  • the composite particles are dispersed in an etchant, stirred, filtered, washed, and dried to obtain micron silicon, Composite particles of dense carbon layer one and porous carbon layer three.
  • the present application also provides a core-shell structure micron silicon-carbon composite material prepared by any of the aforementioned preparation methods.
  • the micron silicon can be crystalline silicon or amorphous silicon-coated crystal. Spherical micron silicon in the state of silicon.
  • the average particle diameter D50 of the crystalline micron silicon of the present application is 1 to 8 ⁇ m, for example, it can be 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 3 ⁇ m, 3.5 ⁇ m, 4 ⁇ m, 4.5 ⁇ m, 5 ⁇ m, 5.5 ⁇ m, 6 ⁇ m, 6.5 ⁇ m, 7 ⁇ m, 7.5 ⁇ m, 8 ⁇ m, etc.
  • the sphericity is 0.3 ⁇ 0.8, for example, it can be 0.3, 0.31, 0.32, 0.33, 034, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.45, 0.46, 0.48, 0.48, 0.5, 0.51, 0.52, 0.54, 0.55, 0.57, 0.58, 0.59, 0.62, 0.64, 0.66, 0.67, 0.68, 0.69, 0.68, 0.69, 0.68, 0.69, 0.69, 0.69, 0.69, 0.
  • the interior of the spherical micron silicon in this application is crystalline silicon and the surface is amorphous silicon.
  • the average particle size D50 of the spherical micron silicon is 1 to 8 ⁇ m, for example, it can be 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 3 ⁇ m, 3.5 ⁇ m, 4 ⁇ m, 4.5 ⁇ m, 5 ⁇ m, 5.5 ⁇ m, 6 ⁇ m, 6.5 ⁇ m, 7 ⁇ m, 7.5 ⁇ m, 8 ⁇ m, etc.
  • the sphericity is 0.7 ⁇ 0.95, for example, it can be 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, etc.
  • Micron silicon in the existing technology is irregularly shaped crystalline silicon with many edges and corners on the surface. Crystalline silicon has anisotropy and anisotropic expansion. During the silicon lithium insertion process, anisotropic volume expansion easily causes failure at the edges and corners. or destroy particle integrity.
  • the spherical micron silicon in this application has a certain thickness of amorphous silicon on the surface. The amorphous silicon is isotropic and expands in the same direction, so that the spherical micron silicon exerts uniform force on its outer coating layer in all directions, which is beneficial to maintaining the Particle structural stability during electrochemical processes.
  • the average particle size D50 of the spherical micron silicon of the present application is 2 to 5 ⁇ m; the sphericity of the spherical micron silicon is 0.8 to 0.95.
  • the specific surface area of the spherical micron silicon of the present application is 0.5-5m 2 /g, for example, it can be 0.5m 2 /g, 1m 2 /g, 1.5m 2 /g, 2m 2 / g, 2.5 m 2 /g, 3m 2 /g, 3.5m 2 /g, 4m 2 /g, 4.5m 2 /g, 5m 2 /g, etc., preferably 1 to 4m 2 /g.
  • the specific surface area of the spherical micron silicon of the present application can be detected by the specific method given in the embodiment, and measured using the BET specific surface tester.
  • the spherical micron silicon particle size distribution of the present application is moderate and the sphericity is high.
  • Such structural advantages enable it to have a lower specific surface area, higher particle fluidity and higher tap density, thereby reducing the difficulty of subsequent processes and having It is beneficial to maintain the stability of the particle structure during the electrochemical process.
  • the thickness of the amorphous silicon in the spherical micron silicon of the present application is 1 to 20nm, for example, it can be 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 11nm , 12nm, 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm, 20nm, etc., preferably 2 to 10nm.
  • the thickness of amorphous silicon can be obtained by averaging multiple measurements through a transmission electron microscope, for example, it can be 2 points, 3 points, 4 points, 5 points, 6 points, 7 points, 8 points, 9 points, 10 points, etc.
  • the structure of the spherical micron silicon of the present application is shown in the TEM picture of Figure 2.
  • the part with visible lattice stripes on the left side of the figure is the crystalline silicon 5 inside the spherical micron silicon; the part without the lattice stripes on the right side is the spherical micron silicon.
  • the thickness of the amorphous silicon in the outer layer is 10 nm.
  • This application can simply prepare the spherical micron silicon of this application through the following method, which method includes the following steps:
  • the crystalline micron silicon is sintered, kept warm, cooled and crushed under an inert atmosphere to obtain spherical micron silicon.
  • the crystalline micron silicon is crystalline micron silicon of the related art.
  • the average particle size D50 of the crystalline micron silicon is 1 to 8 ⁇ m, for example, it can be 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 3 ⁇ m, 3.5 ⁇ m, 4 ⁇ m, 4.5 ⁇ m, 5 ⁇ m, or 5.5 ⁇ m.
  • the sphericity of the crystalline micron silicon is 0.3 to 0.7, for example, it can be 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, etc.
  • the average particle size D50 of the spherical micron silicon of the present application is less than or equal to the average particle size D50 of the crystalline micron silicon.
  • the sphericity of the spherical micron silicon of the present application is greater than the sphericity of the crystalline micron silicon.
  • the inert atmosphere is not limited and can be any inert atmosphere, such as nitrogen or argon.
  • the sintering temperature is 1300-1600°C, for example, it can be 1300°C, 1310°C, 1320°C, 1330°C, 1340°C, 1350°C, 1360°C, 1370°C, 1380°C, 1390°C, 1400°C, 1410°C, 1420°C, 1430°C, 144°C, 1450°C, 1460°C, 1470°C, 1480°C, 1490°C, 1500°C, 1510°C, 1520°C, 1530°C, 1540°C, 1550°C, 1560°C , 1570°C, 1580°C, 1590°C, 1600°C, etc., preferably 1400 to 1500°C.
  • the sintering device in this application. Any device capable of heating up sintering can be used.
  • it can be a dry rotary kiln, an electric furnace, a tube furnace, a box furnace, a roller kiln, etc., and for example, an oxygen-acetylene flame can be used. , oxygen-hydrogen flame and other sintering.
  • the temperature is raised to the sintering temperature at a heating rate of 1 to 10°C/min, preferably 3 to 6°C/min.
  • the heating rate can be, for example, 1°C/min, 1.5°C/min, 2°C/min, 2.5°C/min, 3°C/min, 3.5°C/min, 4°C/min, 4.5°C/min, 5°C/min, 5.5°C/min, 6°C/min, 6.5°C/min, 7°C/min, 7.5°C/min, 8°C/min, 8.5°C/min, 9°C/min, 9.5°C/min, 10°C/min, etc.
  • the sintering temperature is higher than 1300°C.
  • the temperature starts to rise to the sintering temperature at a heating rate of 3 to 6°C/min.
  • the heating rate needs to be adjusted so that it is not too fast to avoid the rapid melting of the silicon edges and the adhesion of the particles.
  • the adhesion can be opened by crushing, the crushing process may create edges and corners.
  • the holding time is 0.5-10h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5 h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, etc., preferably 0.5 to 4h. If the heat preservation time is too short, the edges and corners are not fully melted, and the sphericity is not high; if the heat preservation time is too long, the edges and corners are fully melted and may cause contact transfer between the particles, resulting in adhesion.
  • the cooling rate is 10-100°C/min, for example, it can be 10°C/min, 15°C/min, 20°C/min, 25°C/min, 30°C/min, 35°C/min. min, 40°C/min, 45°C/min, 50°C/min, 55°C/min, 60°C/min, 65°C/min, 70°C/min, 75°C/min, 80°C/min, 85°C/ min, 90°C/min, 95°C/min, 100°C/min, etc., preferably 50 to 80°C/min. Controlling the cooling rate, crystal dislocations form a layer of amorphous silicon.
  • Controlling the cooling rate at 10-100°C/min can make the thickness of amorphous silicon reach 1-20nm.
  • the cooling device in this application, and any device capable of cooling can be used, for example, it can be a method of purging a low-temperature inert atmosphere.
  • the core-shell structure composite material including spherical micron silicon of the present application When used in a lithium-ion battery, the spherical micron silicon expands isotropically, and its spherical structure improves the continuity of the surface coating, and the coating layer is evenly stressed during expansion. , the composite material overcomes the huge expansion effect of micron silicon, thereby reducing the deformation of the battery during cycling and improving the safety performance of the battery. At the same time, the composite material maintains structural stability during the cycle, avoiding the growth of the irreversible SEI film at the interface and the infiltration of electrolyte, thus improving the cycle performance of the battery.
  • the present application also provides an electrode.
  • the electrode of the present application includes an electrode current collector and an electrode active material layer coated on the electrode current collector.
  • the electrode active material layer at least contains spherical micron silicon as the electrode active material.
  • the spherical micron silicon is any of the aforementioned spherical micron silicon or spherical micron silicon prepared by any of the foregoing preparation methods of the present application.
  • the electrode active material layer may also include any of the core-shell structure composite materials mentioned above in this application.
  • the electrode of the present application is preferably a negative electrode.
  • the electrode active material of the present application can be a negative electrode active material, which is not particularly limited, and negative electrode active materials commonly used in this technical field can be used.
  • the electrode active material uses the spherical micron silicon of the present application as the main component.
  • the electrode active material layer may also contain other electrode active materials. Next, other electrode active materials will be described.
  • Examples of the negative electrode active material include highly crystalline carbon graphite (natural graphite, artificial graphite, etc.), low crystalline carbon (soft carbon), hard carbon, carbon black (Ketjen Black (registered trademark), acetylene black , channel carbon black, lamp black, oil furnace carbon black, thermal carbon black, etc.), fullerene, carbon nanotubes, carbon nanofibers, carbon nanohorns, carbon filaments and other carbon materials.
  • examples of negative electrode active materials include Si, Ge, Sn, Pb, Al, In, Zn, H, Ca, Sr, Ba, Ru, Rh, Ir, Pd, Pt, Ag, Au, Cd, and Hg.
  • the negative electrode active material include metal materials such as lithium metal and lithium-transition metal composite oxides such as lithium-titanium composite oxides (for example, lithium titanate Li 4 Ti 5 O 12 ).
  • the material is not limited to these materials, and conventionally known materials that can be used as negative electrode active materials for lithium ion batteries can be used. Only one type of these negative electrode active materials may be used alone, or two or more types may be used in combination.
  • the electrode current collector of the present application may be a negative electrode current collector, which is made of conductive material.
  • the thickness of the electrode current collector is usually about 0.1 to 1000 ⁇ m, preferably about 1 to 100 ⁇ m.
  • the shape of the electrode current collector is not particularly limited.
  • the material constituting the electrode current collector is not particularly limited. For example, it can be copper.
  • the electrode may be prepared by forming the active material layer on the electrode current collector using conventionally known methods, but is not limited thereto. Those skilled in the art can select a suitable method to manufacture electrodes according to the type of battery to be manufactured.
  • the electrode using the electrode active material can be produced by a conventional method. That is, the electrode active material and the conductive agent, as well as the binder and thickener used as needed, can be dry-mixed into a sheet, and the sheet-shaped material can be pressed onto the electrode current collector, or These materials are dissolved or dispersed in a liquid medium to form a slurry, and the slurry is applied to an electrode current collector and dried to form an electrode active material layer on the electrode current collector, thereby obtaining an electrode.
  • the conductive agent may contain any other component that can be used as a conductive agent.
  • it may also include metal materials such as copper and nickel; graphite such as natural graphite and artificial graphite; carbon black such as acetylene black; and carbon materials such as amorphous carbon such as needle coke.
  • metal materials such as copper and nickel; graphite such as natural graphite and artificial graphite; carbon black such as acetylene black; and carbon materials such as amorphous carbon such as needle coke.
  • These conductive agents may be used alone or in combination of two or more in any combination and ratio.
  • the electrode active material layer may further contain a binder.
  • a binder used to produce the electrode active material layer.
  • it may be a material that can be dissolved or dispersed in the liquid medium used in producing the electrode.
  • the solvent used to form the slurry is not particularly limited as long as it can dissolve or disperse the electrode active material, the conductive agent, the binder and, if necessary, the thickener.
  • Water-based solvents can be used. Solvents and any solvent in organic solvents.
  • the electrode active material layer may also contain a thickener.
  • a thickening agent there are no particular restrictions.
  • the present application also provides a battery, which includes a positive electrode, a negative electrode, a separator and an electrolyte, wherein the negative electrode is the aforementioned negative electrode of the present application.
  • a battery in this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity.
  • the battery mentioned in this application may include a battery module or a battery pack.
  • the battery cells of this application may include one or more of lithium ion secondary batteries, lithium ion primary batteries, lithium sulfur batteries, sodium lithium ion batteries, sodium ion batteries and magnesium ion batteries. This application does not limited.
  • the battery cell of the present application may be in the shape of a cylinder, a flat body, a rectangular parallelepiped or other shapes, and the embodiments of the present application are not limited to this. Battery cells are generally divided into three types according to packaging methods: cylindrical battery cells, prismatic battery cells and soft-pack battery cells. This application is not limited thereto.
  • the separator is usually disposed between the positive electrode and the negative electrode.
  • any known separator can be used.
  • resins, glass fibers, inorganic substances, etc. can be used, and materials in the form of porous sheets or nonwoven fabrics that are excellent in liquid retention are preferably used.
  • Electrolyte is filled between the positive and negative electrodes.
  • the electrolyte may be an aqueous electrolyte or a non-aqueous electrolyte.
  • the electrolyte may be an electrolyte, a polymer gel electrolyte, or a solid polymer electrolyte.
  • reagents or instruments used are conventional reagents that can be purchased commercially if the manufacturer is not indicated. or instrument.
  • 1kg of crystalline micron silicon with a D50 of 5 ⁇ m and a sphericity of 0.3 is heated to 1400°C at a rate of 5°C/min in a nitrogen atmosphere. After being kept for 5 hours, it is cooled to room temperature at a rate of 50°C/min. Take it out and crush it to obtain a D50 of 4 ⁇ m, spherical micron silicon with a sphericity of 0.8.
  • 1kg of crystalline micron silicon with a D50 of 6 ⁇ m and a sphericity of 0.5 is heated to 1500°C at 10°C/min in a nitrogen atmosphere. After being kept for 2 hours, it is cooled to room temperature at a rate of 100°C/min. Take it out and crush it to obtain a D50 of 6 ⁇ m. , spherical micron silicon with a sphericity of 0.9.
  • 1kg of crystalline micron silicon with a D50 of 2 ⁇ m and a sphericity of 0.6 is heated to 1400°C at 3°C/min in a nitrogen atmosphere. After being kept for 4 hours, it is cooled to room temperature at a rate of 60°C/min, taken out, and crushed to obtain a D50 of 2 ⁇ m spherical micron silicon with a sphericity of 0.95.
  • 1kg of crystalline micron silicon with a D50 of 4 ⁇ m and a sphericity of 0.3 is heated to 1450°C at a rate of 5°C/min in a nitrogen atmosphere. After incubation for 5 hours, it is cooled to room temperature at a rate of 80°C/min. Take it out and crush it to obtain a D50 of 3 ⁇ m. , spherical micron silicon with a sphericity of 0.8.
  • the difference between this embodiment and Embodiment 3 is that the cooling rate is 50°C/min.
  • the thickness of the dense carbon layer one is 20 nm
  • the thickness of the porous carbon layer is 1 ⁇ m
  • the thickness of the second dense carbon layer is 5 nm.
  • Embodiment 2-1 The difference between this embodiment and Embodiment 2-1 is that the sphericity of crystalline micron silicon is 0.3.
  • the thickness of the dense carbon layer one is 14 nm
  • the thickness of the porous carbon layer is 0.8 ⁇ m
  • the thickness of the second dense carbon layer is 4 nm.
  • Embodiment 2-1 The difference between this embodiment and Embodiment 2-1 is that the D50 of crystalline micron silicon is 8 ⁇ m.
  • the thickness of the dense carbon layer one is 12 nm
  • the thickness of the porous carbon layer is 0.64 ⁇ m
  • the thickness of the second dense carbon layer is 3.2 nm.
  • Embodiment 2-1 The difference between this embodiment and Embodiment 2-1 is that the pore-forming agent is nano-alumina.
  • the thickness of the dense carbon layer one is 20 nm
  • the thickness of the porous carbon layer is 0.92 ⁇ m
  • the thickness of the second dense carbon layer is 5 nm.
  • Example 2-1 The difference between this embodiment and Example 2-1 is that the average particle size D50 of the pore-forming agent is 50 nm.
  • the thickness of the dense carbon layer one is 20 nm
  • the thickness of the porous carbon layer is 1.24 ⁇ m
  • the thickness of the second dense carbon layer is 3.6 nm.
  • Example 2-1 The difference between this embodiment and Example 2-1 is that the average particle size D50 of the pore-forming agent is 500 nm.
  • the thickness of the dense carbon layer one is 20 nm
  • the thickness of the porous carbon layer is 0.76 ⁇ m
  • the thickness of the second dense carbon layer is 6 nm.
  • Example 2-1 The difference between this embodiment and Example 2-1 is that the carbon sources in steps (1), (2) and (4) are all phenolic resins.
  • the thickness of the dense carbon layer one is 16 nm
  • the thickness of the porous carbon layer is 0.68 ⁇ m
  • the thickness of the second dense carbon layer is 4 nm.
  • Example 2-1 The difference between this embodiment and Example 2-1 is that the carbon sources in steps (1), (2) and (4) are all humic acid.
  • the thickness of the dense carbon layer one is 16 nm
  • the thickness of the porous carbon layer is 1.12 ⁇ m
  • the thickness of the second dense carbon layer is 6 nm.
  • Embodiment 2-1 The difference between this embodiment and Embodiment 2-1 is that the amount of nano-magnesium oxide is 100g.
  • the thickness of the dense carbon layer one is 20 nm
  • the thickness of the porous carbon layer is 0.2 ⁇ m
  • the thickness of the second dense carbon layer is 5 nm.
  • Embodiment 2-1 The difference between this embodiment and Embodiment 2-1 is that the amount of nano-magnesium oxide is 250g.
  • the thickness of the dense carbon layer one is 20 nm
  • the thickness of the porous carbon layer is 0.6 ⁇ m
  • the thickness of the second dense carbon layer is 5 nm.
  • the thickness of the dense carbon layer one is 18 nm
  • the thickness of the porous carbon layer is 0.88 ⁇ m
  • the thickness of the second dense carbon layer is 4 nm.
  • the thickness of the dense carbon layer one is 24 nm
  • the thickness of the porous carbon layer is 1.24 ⁇ m
  • the thickness of the second dense carbon layer is 7.2 nm.
  • Example 2-11 The difference between this embodiment and Example 2-11 is that the crystalline micron silicon with a D50 of 4 ⁇ m and a sphericity of 0.8 is replaced with the D50 of 4 ⁇ m, a sphericity of 0.8 and a crystalline interior prepared in Example 1-1. Silicon, spherical micron silicon with amorphous silicon surface.
  • the thickness of the carbon layer is 55nm.
  • the core-shell structure composite material (90wt%) obtained in Examples 2-1 to 2-13 was mixed with conductive agent (1wt% CNT and 3wt% SP), binder (4wt% CMC and 2wt% SBR) and deionized Mix water into a slurry, apply it, dry it and cut it to obtain a lithium electrode sheet, where "wt%" represents the percentage of each component in the total weight of the core-shell structure composite material, conductive agent and binder. Assemble the lithium electrode sheet and conventional electrolyte into a button half cell, and perform charge and discharge tests. The test conditions are: in the voltage range of 5mV-0.8V, activate at 0.1C/0.1C for 2 turns, and cycle at 0.3C/0.3C. After testing, the electrochemical performance parameters of the batteries made with the materials of Examples 2-1 to 2-13 are as shown in Table 5 below.
  • Example 2-5 2785 88.9 88
  • Example 2-6 2802 88.5
  • Example 2-7 2678 87.2
  • Example 2-8 2843 89.6 79
  • Example 2-9 2821 89.4
  • Example 2-10 2842 89.8
  • Example 2-11 2863 90.1
  • Example 2-12 2763 88.6
  • Example 2-13 1957 83.6 90
  • Example 2-14 2851 90.3 92 Comparative example 1 2762 90.8 28

Abstract

The present application discloses a core-shell structure micron silicon-carbon composite material, comprising: a core formed by micron silicon; and a carbon shell layer coated on the core, wherein the carbon shell layer sequentially comprises, from inside to outside: a compact carbon layer 1, a porous carbon layer, and a compact carbon layer 2. The present application further discloses a preparation method for the core-shell structure micron silicon-carbon composite material, an electrode comprising the core-shell structure micron silicon-carbon composite material, a battery comprising the electrode, a circuit comprising the battery, and an electric device comprising the circuit.

Description

核壳结构微米硅碳复合材料及制备方法、电极及电池Core-shell structure micron silicon carbon composite materials and preparation methods, electrodes and batteries 技术领域Technical field
本申请涉及锂电池技术领域，具体涉及一种核壳结构微米硅碳复合材料及其制备方法、包括该核壳结构微米硅碳复合材料的电极及电池。The present application relates to the technical field of lithium batteries, and specifically relates to a core-shell structure micron silicon-carbon composite material and a preparation method thereof, electrodes and batteries including the core-shell structure micron silicon-carbon composite material.
背景技术Background technique
目前，硅材料由于其高比容量成为最具发展前景的下一代锂电池负极材料。纳米结构硅在一定程度上可以缓解硅颗粒的破碎，成为目前研究的重要方向。但是纳米硅成本高、批次稳定性较差、活性大容易氧化、易团聚、难以分散的缺点导致其制备困难、一致性较差。At present, silicon material has become the most promising next-generation lithium battery anode material due to its high specific capacity. Nanostructured silicon can alleviate the breakage of silicon particles to a certain extent and has become an important direction of current research. However, the disadvantages of nano-silicon are high cost, poor batch stability, high activity, easy to oxidize, easy to agglomerate, and difficult to disperse, which makes its preparation difficult and poor consistency.
微米硅可以解决以上问题，其由于成本低、制备工艺简单、首效高的特点逐渐受到重视。但是微米硅相较于纳米硅更加剧烈的体积膨胀效应、更差的电子电导，导致其循环性能急速衰减，一般的核壳结构也难以抵挡硅的体积膨胀。Micron silicon can solve the above problems, and it has gradually attracted attention due to its low cost, simple preparation process and high first efficiency. However, compared with nano-silicon, micron silicon has a more severe volume expansion effect and poorer electronic conductivity, resulting in a rapid decline in its cycle performance. General core-shell structures are also difficult to withstand the volume expansion of silicon.
目前涉及微米硅结构改进的技术非常少，都是以纳米硅为基础进行硅碳材料的构筑。为了缓解纳米硅材料的体积效应，维持颗粒完整，构筑多孔结构如核壳结构，为膨胀提供空间是目前的主要改进手段。但是以上结构中的空腔直接与硅材料相接，导致电子、离子无法形成面扩散，仅为点扩散；同时预留空间导致的无应力包覆层会使循环中硅颗粒破裂后的一次颗粒散落在预留空间中，打断了锂离子、电子的扩散路径；综上导致电化学过程中阻抗持续增加，循环性能降低，无法更进一步的提升性能。At present, there are very few technologies involving the improvement of micron silicon structure, and they are all based on nano-silicon to construct silicon-carbon materials. In order to alleviate the volume effect of nano-silicon materials and maintain the integrity of the particles, building porous structures such as core-shell structures to provide space for expansion is currently the main improvement method. However, the cavity in the above structure is directly connected to the silicon material, causing electrons and ions to be unable to form surface diffusion and only point diffusion; at the same time, the stress-free coating layer caused by the reserved space will cause the primary particles after the silicon particles are broken during the cycle. Scattered in the reserved space, interrupting the diffusion path of lithium ions and electrons; in summary, the impedance continues to increase during the electrochemical process, the cycle performance decreases, and the performance cannot be further improved.
发明内容Contents of the invention
为克服现有技术中的微米硅颗粒作为电极材料的技术难点，本申请旨在提供一种核壳结构微米硅碳复合材料，以及一种核壳结构微米硅碳复合材料的制备方法，有效提高了电池的循环性能和库伦效率。In order to overcome the technical difficulties of using micron silicon particles as electrode materials in the prior art, this application aims to provide a core-shell structure micron silicon-carbon composite material and a preparation method of a core-shell structure micron silicon-carbon composite material, which can effectively improve improve the cycle performance and Coulombic efficiency of the battery.
本申请的具体技术方案如下：The specific technical solutions of this application are as follows:
1.一种核壳结构微米硅碳复合材料，其特征在于，其包括：1. A core-shell structure micron silicon carbon composite material, characterized in that it includes:
由微米硅形成的内核；和A core formed from micron silicon; and
包覆在所述内核上的碳壳层，其中所述碳壳层由内向外依次包括致密碳层一、多孔碳层和致密碳层二。A carbon shell layer covering the core, wherein the carbon shell layer includes a dense carbon layer one, a porous carbon layer and a dense carbon layer two from the inside to the outside.
2.根据项1所述的核壳结构微米硅碳复合材料，其特征在于，所述微米硅的平均粒径D50为1～8μm，球形度为0.3～0.95。2. The core-shell structure micron silicon-carbon composite material according to item 1, characterized in that the average particle size D50 of the micron silicon is 1 to 8 μm, and the sphericity is 0.3 to 0.95.
3.根据项1或2所述的核壳结构微米硅碳复合材料，其特征在于，所述致密碳层一的厚度为所述微米硅平均粒径D50的0.05％～1％，优选为0.1％～0.4％；3. The core-shell structure micron silicon carbon composite material according to item 1 or 2, characterized in that the thickness of the dense carbon layer 1 is 0.05% to 1% of the average particle diameter D50 of the micron silicon, preferably 0.1 %~0.4%;
优选地，所述致密碳层一的孔隙率为10％～50％，优选为10％～30％。Preferably, the porosity of the dense carbon layer 1 is 10% to 50%, preferably 10% to 30%.
4.根据项1～3中任一项所述的核壳结构微米硅碳复合材料，其特征在于，所述多孔碳层的厚度为所述微米硅平均粒径D50的5％～25％，优选为10％～20％；4. The core-shell structure micron silicon carbon composite material according to any one of items 1 to 3, characterized in that the thickness of the porous carbon layer is 5% to 25% of the average particle diameter D50 of the micron silicon, Preferably, it is 10% to 20%;
优选地，所述多孔碳层的多孔由造孔剂和刻蚀剂形成，所述造孔剂选自纳米氧化锌、纳米氧化镁、纳米氧化铝、纳米氧化硅、纳米氧化铜、纳米氧化铁和纳米氧化锰中的一种或两种以上；Preferably, the pores of the porous carbon layer are formed by a pore-forming agent and an etchant, and the pore-forming agent is selected from the group consisting of nano zinc oxide, nano magnesium oxide, nano aluminum oxide, nano silicon oxide, nano copper oxide, and nano iron oxide. and one or more types of nanomanganese oxide;
优选地，所述造孔剂的平均粒径D50为50～500nm，优选为50～200nm；Preferably, the average particle size D50 of the pore-forming agent is 50 to 500 nm, preferably 50 to 200 nm;
优选地，所述多孔的平均孔径不小于所述造孔剂的平均粒径D50；Preferably, the average pore diameter of the pores is not less than the average particle diameter D50 of the pore-forming agent;
优选地，所述刻蚀剂选自盐酸、硝酸和氢氟酸中的一种或两种或三种。Preferably, the etchant is selected from one, two or three types of hydrochloric acid, nitric acid and hydrofluoric acid.
5.根据项1～4中任一项所述的核壳结构微米硅碳复合材料，其特征在于，所述致密碳层二的厚度为所述微米硅平均粒径D50的0.05％～1％，优选为0.1％～0.2％；5. The core-shell structure micron silicon-carbon composite material according to any one of items 1 to 4, characterized in that the thickness of the second dense carbon layer is 0.05% to 1% of the average particle diameter D50 of the micron silicon. , preferably 0.1% to 0.2%;
优选地，所述致密碳层二的孔隙率为5％～30％，优选为5％～25％。Preferably, the porosity of the second dense carbon layer is 5% to 30%, preferably 5% to 25%.
6.根据项1～5中任一项所述的核壳结构微米硅碳复合材料，其特征在于，所述碳壳层的肖氏硬度为10～50HSD，优选为25～40HSD。6. The core-shell structure micron silicon-carbon composite material according to any one of items 1 to 5, characterized in that the Shore hardness of the carbon shell layer is 10-50HSD, preferably 25-40HSD.
7.根据项1～6中任一项所述的核壳结构微米硅碳复合材料，其特征在于，所述致密碳层一的碳源选自沥青、酚醛树脂、腐殖酸、单宁酸、聚合多巴胺、聚吡咯、甲烷和乙烷中的一种或两种以上；或者，7. The core-shell structure micron silicon carbon composite material according to any one of items 1 to 6, characterized in that the carbon source of the dense carbon layer one is selected from the group consisting of asphalt, phenolic resin, humic acid, and tannic acid. , one or more of polymerized dopamine, polypyrrole, methane and ethane; or,
所述多孔碳层的碳源选自沥青、酚醛树脂、腐殖酸、单宁酸、聚合多巴胺、聚吡咯、甲烷和乙烷中的一种或两种以上；或者，The carbon source of the porous carbon layer is selected from one or more of asphalt, phenolic resin, humic acid, tannic acid, polymerized dopamine, polypyrrole, methane and ethane; or,
所述致密碳层二的碳源选自沥青、酚醛树脂、腐殖酸、单宁酸、聚合多巴胺、聚吡咯、甲烷和乙烷中的一种或两种以上。The carbon source of the dense carbon layer 2 is selected from one or more of asphalt, phenolic resin, humic acid, tannic acid, polymerized dopamine, polypyrrole, methane and ethane.
8.根据项1～7中任一项所述的核壳结构微米硅碳复合材料，其特征在于，所述核壳结构微米硅碳复合材料的真密度为1.2～2.1g/cc，优选1.4～1.8g/cc。8. The core-shell structure micron silicon carbon composite material according to any one of items 1 to 7, characterized in that the core-shell structure micron silicon carbon composite material has a true density of 1.2 to 2.1 g/cc, preferably 1.4 ~1.8g/cc.
9.一种核壳结构微米硅碳复合材料的制备方法，其特征在于，其包括下述步骤：9. A method for preparing core-shell structure micron silicon-carbon composite material, characterized in that it includes the following steps:
使用碳源一对微米硅进行包覆，得到包括微米硅和致密碳层一的复合颗粒一；Use a carbon source to coat a pair of micron silicon to obtain a composite particle 1 including micron silicon and a dense carbon layer 1;
使用碳源二和造孔剂对所述复合颗粒一进行包覆，得到复合颗粒二；Use carbon source two and a pore-forming agent to coat the composite particle one to obtain composite particle two;
将所述复合颗粒二在惰性气氛下烧结，分散于刻蚀剂中，得到包括微米硅、致密碳层一和多孔碳层的复合颗粒三；The composite particle two is sintered in an inert atmosphere and dispersed in an etchant to obtain a composite particle three including micron silicon, a dense carbon layer one and a porous carbon layer;
使用碳源三对所述复合颗粒三进行包覆，烧结，得到包括微米硅、致密碳层一、多孔碳层和致密碳层二的核壳结构微米硅碳复合材料。The composite particle three is coated with carbon source three and sintered to obtain a core-shell structure micron silicon-carbon composite material including micron silicon, dense carbon layer one, porous carbon layer and dense carbon layer two.
10.根据项9所述的核壳结构微米硅碳复合材料的制备方法，其特征在于，使用碳源二和造孔剂对所述复合颗粒一进行包覆，烧结，得到复合颗粒二。10. The preparation method of core-shell structure micron silicon carbon composite material according to item 9, characterized in that the composite particle one is coated with a carbon source two and a pore-forming agent and sintered to obtain a composite particle two.
11.根据项9或10所述的制备方法，其特征在于，使用碳源三对所述复合颗粒三进行包覆后再烧结的烧结温度为600～1100℃，优选为700～1000℃，优选使用碳源三对所述复合颗粒三进行包覆后再烧结的烧结时间为2～6h。11. The preparation method according to item 9 or 10, characterized in that the sintering temperature for coating the composite particles three with carbon source three and then sintering is 600 to 1100°C, preferably 700 to 1000°C, preferably The sintering time for coating the composite particles three using carbon source three and then sintering is 2 to 6 hours.
12.根据项10所述的制备方法，其特征在于，使用碳源二和造孔剂对所述复合颗粒一进行包覆后再烧结的烧结温度为700～1000℃，优选为800～900℃，优选使用碳源二和造孔剂对所述复合颗粒一进行包覆后再烧结的烧结时间为1～3h。12. The preparation method according to item 10, characterized in that the sintering temperature after coating the composite particles one with a carbon source two and a pore-forming agent is 700 to 1000°C, preferably 800 to 900°C. , it is preferable that the sintering time for coating the composite particles one with the carbon source two and the pore-forming agent and then sintering is 1 to 3 hours.
13.根据项9～12中任一项所述的制备方法，其特征在于，所述包覆为固相包覆。13. The preparation method according to any one of items 9 to 12, characterized in that the coating is solid phase coating.
14.一种由项9～13中任一项所述的制备方法制得的核壳结构微米硅碳复合材料。14. A core-shell structure micron silicon-carbon composite material prepared by the preparation method described in any one of items 9 to 13.
15.根据项1～8中任一项所述的核壳结构微米硅碳复合材料，或根据项9～13中任一项所述的制备方法，其特征在于，所述微米硅为晶态微米硅，其平均粒径D50为1～8μm，球形度为0.3～0.8。15. The core-shell structure micron silicon carbon composite material according to any one of items 1 to 8, or the preparation method according to any one of items 9 to 13, characterized in that the micron silicon is in a crystalline state Micron silicon has an average particle size D50 of 1 to 8 μm and a sphericity of 0.3 to 0.8.
16.根据项1～8中任一项所述的核壳结构微米硅碳复合材料，或根据项9～13中任一项所述的制备方法，其特征在于，所述微米硅为球形微米硅，其内部为晶态硅，表面为非晶态硅，所述球形微米硅的平均粒径D50为1～8μm， 球形度为0.7～0.95；16. The core-shell structure micron silicon carbon composite material according to any one of items 1 to 8, or the preparation method according to any one of items 9 to 13, characterized in that the micron silicon is spherical micron Silicon, the interior of which is crystalline silicon and the surface is amorphous silicon. The average particle size D50 of the spherical micron silicon is 1 to 8 μm, and the sphericity is 0.7 to 0.95;
优选地，所述球形微米硅的平均粒径D50为2～5μm；Preferably, the average particle size D50 of the spherical micron silicon is 2 to 5 μm;
优选地，所述球形微米硅的球形度为0.8～0.95；Preferably, the sphericity of the spherical micron silicon is 0.8 to 0.95;
优选地，所述球形微米硅的比表面积为0.5～5m 2/g，优选为1～4m 2/g； Preferably, the specific surface area of the spherical micron silicon is 0.5 to 5 m 2 /g, preferably 1 to 4 m 2 /g;
优选地，所述非晶态硅的厚度为1～20nm，优选为2～10nm。Preferably, the thickness of the amorphous silicon is 1 to 20 nm, preferably 2 to 10 nm.
17.一种电极，其特征在于，其包括电极集流体和涂覆在所述电极集流体表面的电极活性物质层，所述电极活性物质层包括项1～8和14中任一项所述的核壳结构微米硅碳复合材料，或由项9～13中任一项所述的制备方法制得的核壳结构微米硅碳复合材料；17. An electrode, characterized in that it includes an electrode current collector and an electrode active material layer coated on the surface of the electrode current collector, and the electrode active material layer includes any one of items 1 to 8 and 14. Core-shell structure micron silicon-carbon composite materials, or core-shell structure micron silicon-carbon composite materials prepared by the preparation method described in any one of items 9 to 13;
优选地，所述电极为负极。Preferably, the electrode is a negative electrode.
18.一种电池，其特征在于，其包括正极、负极、隔膜和电解质，其中所述负极是项17所述的负极。18. A battery, characterized in that it includes a positive electrode, a negative electrode, a separator and an electrolyte, wherein the negative electrode is the negative electrode described in item 17.
发明的效果Effect of the invention
(1)本申请的核壳结构微米硅碳复合材料具体结构为微米硅-致密碳层一-多孔碳层-致密碳层二。各个碳层间是有机联系的，并非作为单独的组分存在。致密碳层一紧密包覆微米硅，在循环中提供向内压力，维持微米硅颗粒破碎后产生的小颗粒之间的物理接触，同时作为膨胀力传递介质，将应力传递给多孔碳层进行吸收；并避免硅直接与多孔碳层中的空腔接触，防止硅破碎后的细微颗粒掉入空腔中，失去电化学活性。多孔碳层具有众多的空腔，为可逆压缩空间，为硅的膨胀提供空间，并利用应力的反向作用，在脱锂态时压缩致密碳层一，使致密碳层一将电化学过程后破碎的微米硅颗粒进行紧密包裹，维持离子/电子通道。致密碳层二作为坚固的包覆层，维持多孔碳层受到微米硅膨胀应力时的结构完整和机械稳定性，致密碳层二与多孔碳层结合，有效进行膨胀应力的吸收和释放。同时，致密碳层二隔绝电解液的渗入，避免多孔碳层众多活性位点与电解液发生副反应，从而提高循环性能和库伦效率。(1) The specific structure of the core-shell structure micron silicon-carbon composite material of this application is micron silicon-dense carbon layer one-porous carbon layer-dense carbon layer two. Each carbon layer is organically connected and does not exist as a separate component. The dense carbon layer tightly covers the micron silicon, providing inward pressure during circulation, maintaining physical contact between the small particles produced after the micron silicon particles are broken, and at the same time serving as an expansion force transmission medium to transfer stress to the porous carbon layer for absorption ; And avoid direct contact between silicon and the cavities in the porous carbon layer to prevent the fine particles after broken silicon from falling into the cavities and losing electrochemical activity. The porous carbon layer has numerous cavities, which provide reversible compression space and space for the expansion of silicon. The reverse effect of stress is used to compress the dense carbon layer during the delithiation state, so that the dense carbon layer will be released after the electrochemical process. The broken micron silicon particles are tightly packed to maintain ion/electron channels. The dense carbon layer 2 serves as a strong coating layer to maintain the structural integrity and mechanical stability of the porous carbon layer when it is subjected to micron silicon expansion stress. The dense carbon layer 2 is combined with the porous carbon layer to effectively absorb and release the expansion stress. At the same time, the dense carbon layer isolates the infiltration of electrolyte and avoids side reactions between the many active sites of the porous carbon layer and the electrolyte, thereby improving cycle performance and Coulombic efficiency.
(2)本申请的核壳结构微米硅碳复合材料多孔碳层有连接致密碳层一和致密碳层二的碳支柱，在电化学过程中碳支柱起到传导离子、电子的作用。避免核壳结构中空腔层的存在阻隔离子、电子的传导。(2) The porous carbon layer of the core-shell structure micron silicon-carbon composite material of this application has carbon pillars connecting the dense carbon layer one and the dense carbon layer two. The carbon pillars play the role of conducting ions and electrons during the electrochemical process. Avoid the existence of cavity layers in the core-shell structure from blocking the conduction of isolators and electrons.
(3)本申请的核壳结构微米硅碳复合材料，既能缓解微米硅的体积膨 胀，维持颗粒稳定性；又能对循环后破碎的颗粒提供一个向内压力，维持破碎后一次颗粒的物理接触，保持电子、离子扩散路径，提高循环性能。(3) The core-shell structure micron silicon-carbon composite material of this application can not only alleviate the volume expansion of micron silicon and maintain particle stability; it can also provide an inward pressure for the broken particles after circulation, maintaining the physical properties of the primary particles after being broken. Contact to maintain electron and ion diffusion paths and improve cycle performance.
(4)本申请从微米硅的结构改性入手，有效推进了微米硅的实用化进程。(4) This application starts from the structural modification of micron silicon and effectively promotes the practical application of micron silicon.
附图说明Description of the drawings
图1为本申请的一个具体实施方式的核壳结构微米硅碳复合材料结构示意图。Figure 1 is a schematic structural diagram of a micron silicon-carbon composite material with a core-shell structure according to a specific embodiment of the present application.
图2为本申请一个具体实施方式的球形微米硅的TEM图。Figure 2 is a TEM image of spherical micron silicon according to a specific embodiment of the present application.
符号说明Symbol Description
1微米硅          2致密碳层一        3多孔碳层1 micron silicon 2 dense carbon layers 1 3 porous carbon layers
4致密碳层二      5晶态硅            6非晶态硅4 Dense carbon layer 2 5 Crystalline silicon 6 Amorphous silicon
具体实施方式Detailed ways
下面对本申请做以详细说明。虽然以下显示了本申请的具体实施方式，然而应当理解，可以以各种形式实现本申请而不应被这里阐述的实施方式所限制。相反，提供这些实施方式是为了能够更透彻地理解本申请，并且能够将本申请的范围完整地传达给本领域的技术人员。This application will be described in detail below. Although specific embodiments of the present application are shown below, it should be understood that the present application can be implemented in various forms and should not be limited to the embodiments set forth here. Rather, these embodiments are provided so that a thorough understanding of the present application will be provided, and the scope of the present application will be fully conveyed to those skilled in the art.
需要说明的是，在通篇说明书及权利要求当中所提及的“包含”或“包括”为开放式用语，故应解释成“包含但不限定于”。说明书后续描述为实施本申请的较佳实施方式，然而所述描述乃以说明书的一般原则为目的，并非用以限定本申请的范围。本申请的保护范围当视所附权利要求所界定者为准。It should be noted that the words "include" or "include" mentioned throughout the description and claims are open-ended terms, and therefore should be interpreted as "include but not limited to". The following descriptions of the description are preferred embodiments for implementing the present application. However, the descriptions are for the purpose of general principles of the description and are not intended to limit the scope of the present application. The scope of protection of this application shall be determined by the appended claims.
1.核壳结构微米硅碳复合材料1. Core-shell structure micron silicon carbon composite material
一方面，本申请提供一种核壳结构微米硅碳复合材料，其包括：On the one hand, this application provides a core-shell structure micron silicon carbon composite material, which includes:
由微米硅形成的内核；和A core formed from micron silicon; and
包覆在所述内核上的碳壳层，其中所述碳壳层由内向外依次包括致密碳层一、多孔碳层和致密碳层二。A carbon shell layer covering the core, wherein the carbon shell layer includes a dense carbon layer one, a porous carbon layer and a dense carbon layer two from the inside to the outside.
本申请的核壳结构微米硅碳复合材料，将空腔构筑在碳包覆层中，避免了空腔与硅直接接触造成的离子、电子传导的障碍。内部的致密碳层一包裹微米硅，在循环时包覆层形成向内的压力，保证微米硅破碎后的颗粒依旧维 持物理接触，保持电子、离子电导。表面的致密碳层二与内部的多孔碳层结合，共同进行膨胀应力的吸收和释放。同时，致密碳层二隔绝电解液的渗入，避免多孔碳层众多活性位点与电解液发生副反应，从而提高循环性能和库伦效率。The core-shell structure micron silicon-carbon composite material of the present application constructs the cavity in the carbon coating layer, which avoids the obstacles in ion and electron conduction caused by the direct contact between the cavity and silicon. The internal dense carbon layer wraps the micron silicon, and the coating forms inward pressure during circulation, ensuring that the particles after the micron silicon is broken still maintain physical contact and maintain electronic and ion conductivity. The dense carbon layer 2 on the surface is combined with the porous carbon layer inside to jointly absorb and release expansion stress. At the same time, the dense carbon layer isolates the infiltration of electrolyte and avoids side reactions between the many active sites of the porous carbon layer and the electrolyte, thereby improving cycle performance and Coulombic efficiency.
本申请中的“由内向外”是指由内核向碳壳层方向。“Inside-out” in this application refers to the direction from the core to the carbon shell.
在一个具体实施方式中，如图1所示，所述核壳结构微米硅碳复合材料由：由微米硅1形成的内核以及包覆在所述内核上的碳壳层组成，其中所述碳壳层由内向外依次包括致密碳层一2、多孔碳层3和致密碳层二4。In a specific embodiment, as shown in Figure 1, the core-shell structure micron silicon-carbon composite material is composed of: a core formed of micron silicon 1 and a carbon shell layer covering the core, wherein the carbon The shell layer includes a dense carbon layer 2, a porous carbon layer 3 and a dense carbon layer 2 4 from the inside to the outside.
在一个具体实施方式中，本申请的微米硅的平均粒径D50为1～8μm，例如可为1μm、1.5μm、2μm、2.5μm、3μm、3.5μm、4μm、4.5μm、5μm、5.5μm、6μm、6.5μm、7μm、7.5μm、8μm等，球形度为0.3～0.95，例如可为0.3、0.31、0.32、0.33、0.34、0.35、0.36、0.37、0.38、0.39、0.4、0.41、0.42、0.43、0.44、0.45、0.45、0.46、0.47、0.48、0.49、0.5、0.51、0.52、0.53、0.54、0.55、0.56、0.57、0.58、0.59、0.6、0.61、0.62、0.63、0.64、0.65、0.66、0.67、0.68、0.69、0.7、0.71、0.72、0.73、0.74、0.75、0.76、0.77、0.78、0.79、0.80、0.81、0.82、0.83、0.84、0.85、0.86、0.87、0.88、0.89、0.90、0.91、0.92、0.93、0.94、0.95等。In a specific embodiment, the average particle size D50 of the micron silicon of the present application is 1 to 8 μm, for example, it can be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, etc., the sphericity is 0.3~0.95, for example, it can be 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43 、0.44、0.45、0.45、0.46、0.47、0.48、0.49、0.5、0.51、0.52、0.53、0.54、0.55、0.56、0.57、0.58、0.59、0.6、0.61、0.62、0.63、0.64、0.65、0.66、0.67 , 0.68, 0.69, 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.9 2 , 0.93, 0.94, 0.95, etc.
本申请的“平均粒径D50”指一个样品的累计粒度分布数达到50％时所对应的粒径。它的物理意义是粒径小于它的颗粒占总量的50％。粒径分布可以采用本领域技术人员采用的常规仪器来进行检测，例如采用激光粒度分析仪进行检测。The “average particle size D50” in this application refers to the particle size corresponding to when the cumulative particle size distribution number of a sample reaches 50%. Its physical meaning is that particles with a particle size smaller than it account for 50% of the total. Particle size distribution can be detected using conventional instruments used by those skilled in the art, such as using a laser particle size analyzer.
本申请的“球形度”是表征颗粒形貌的参数，形貌上越接近球的颗粒，其球形度越接近于1。与物体相同体积的球体的表面积和物体的表面积的比为球形度。球的球形度等于1，其它物体球形度小于1。任意颗粒的球形度公式为：
Figure PCTCN2022135031-appb-000001
其中，ψ为颗粒球形度，Vp为颗粒体积，Sp为颗粒表面积。本申请的球形度例如可以通过实施例中给出的具体方法检测，利用动态图像颗粒分析仪进行测定。 The “sphericity” used in this application is a parameter that characterizes the morphology of particles. The closer a particle is to a sphere in shape, the closer its sphericity is to 1. The ratio of the surface area of a sphere with the same volume as the object to the surface area of the object is sphericity. The sphericity of the ball is equal to 1, and the sphericity of other objects is less than 1. The sphericity formula of any particle is:
Figure PCTCN2022135031-appb-000001
Among them, ψ is the particle sphericity, Vp is the particle volume, and Sp is the particle surface area. The sphericity of the present application can be detected, for example, by the specific methods given in the examples, and measured using a dynamic image particle analyzer.
在一个具体实施方式中，所述致密碳层一的厚度为所述微米硅平均粒径D50的0.05％～1％，例如可为0.05％、0.07％、0.09％、0.1％、0.1％、0.15％、 0.2％、0.25％、0.3％、0.35％、0.4％、0.45％、0.5％、0.55％、0.6％、0.65％、0.7％、0.75％、0.8％、0.85％、0.9％、0.95％、1％等，优选为0.1％～0.4％。致密碳层一包裹微米硅，在循环时包覆层形成向内的压力，保证微米硅破碎后的颗粒依旧维持物理接触，保持电子、离子电导；如果致密碳层一厚度过小，则无法承受微米硅的膨胀并将其膨胀应力转移至多孔碳层，导致构筑的包覆层结构失效，材料的电化学性能下降；如果致密碳层一厚度过大，电子导电通道受到影响，同时影响材料的比容量及首效。In a specific embodiment, the thickness of the dense carbon layer I is 0.05% to 1% of the average particle size D50 of micron silicon, for example, it can be 0.05%, 0.07%, 0.09%, 0.1%, 0.1%, 0.15 %, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, etc., preferably 0.1% to 0.4%. The dense carbon layer wraps the micron silicon. During circulation, the coating layer forms inward pressure to ensure that the particles after the micron silicon is broken still maintain physical contact and maintain electronic and ion conductivity. If the thickness of the dense carbon layer is too small, it will not be able to withstand it. Micron silicon expands and transfers its expansion stress to the porous carbon layer, resulting in the failure of the cladding layer structure and a decrease in the electrochemical performance of the material; if the thickness of the dense carbon layer is too large, the electronic conductive channels are affected, and at the same time the material's electrochemical properties are affected. Specific capacity and first effect.
本申请的致密碳层一的厚度可以通过透射电镜进行多点测量取平均值得到，例如可为2个点、3个点、4个点、5个点、6个点、7个点、8个点、9个点、10个点等。The thickness of the dense carbon layer 1 of the present application can be obtained by measuring multiple points through a transmission electron microscope and taking the average value. For example, it can be 2 points, 3 points, 4 points, 5 points, 6 points, 7 points, 8 points. points, 9 points, 10 points, etc.
在一个具体实施方式中，所述致密碳层一的孔隙率为10％～50％，例如可为10％、12％、14％、16％、18％、20％、22％、24％、26％、28％、30％、32％、34％、36％、38％、40％、42％、44％、46％、48％、50％等，优选为10％～30％。致密碳层一需要将微米硅膨胀的作用力传递给多孔碳层，此过程中承受着非常巨大的作用力，本申请这样的较小孔隙率能够降低碳层结构中的缺陷，提高材料的屈服强度。本申请的致密碳层一的孔隙率例如可通过真密度测试仪进行测定。In a specific embodiment, the porosity of the dense carbon layer one is 10% to 50%, for example, it can be 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, etc., preferably 10% to 30%. The dense carbon layer needs to transfer the expansion force of micron silicon to the porous carbon layer, and it bears a very huge force in this process. The smaller porosity in this application can reduce defects in the carbon layer structure and improve the yield of the material. strength. The porosity of the dense carbon layer 1 of the present application can be measured, for example, by a true density tester.
在一个具体实施方式中，所述多孔碳层的厚度为所述微米硅平均粒径D50的5％～25％，例如可为5％、6％、7％、8％、9％、10％、11％、12％、13％、14％、15％、16％、17％、18％、19％、20％、21％、22％、23％、24％、25％等，优选为10％～20％。本申请的多孔碳层的厚度例如可通过透射电镜进行多点测量取平均值得到，例如可为2个点、3个点、4个点、5个点、6个点、7个点、8个点、9个点、10个点等。In a specific embodiment, the thickness of the porous carbon layer is 5% to 25% of the average particle diameter D50 of micron silicon, for example, it can be 5%, 6%, 7%, 8%, 9%, 10% , 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, etc., preferably 10 %~20%. The thickness of the porous carbon layer of the present application can be obtained by measuring multiple points through a transmission electron microscope and taking the average, for example, it can be 2 points, 3 points, 4 points, 5 points, 6 points, 7 points, or 8 points. points, 9 points, 10 points, etc.
在一个具体实施方式中，所述多孔碳层的多孔由造孔剂和刻蚀剂形成，首先加入造孔剂与碳源混合，然后加入能够与造孔剂反应的刻蚀剂，形成所述多孔，造孔剂与刻蚀剂的反应产物以及多余的刻蚀剂可通过清洗以及后续的烧结步骤去除。所述造孔剂可选自纳米氧化锌、纳米氧化镁、纳米氧化铝、纳米氧化硅、纳米氧化铜、纳米氧化铁和纳米氧化锰中的一种或两种以上；所述刻蚀剂可选自盐酸、硝酸和氢氟酸中的一种或两种或三种。In a specific embodiment, the pores of the porous carbon layer are formed by a pore-forming agent and an etchant. First, the pore-forming agent is added and mixed with the carbon source, and then an etchant that can react with the pore-forming agent is added to form the said pore-forming agent. Porous, reaction products of pore formers and etchants as well as excess etchant can be removed by cleaning and subsequent sintering steps. The pore-forming agent can be selected from one or more of nano zinc oxide, nano magnesium oxide, nano aluminum oxide, nano silicon oxide, nano copper oxide, nano iron oxide and nano manganese oxide; the etchant can be Select one, two or three types from hydrochloric acid, nitric acid and hydrofluoric acid.
本申请通过控制造孔剂的量，能够实现造孔剂颗粒与造孔剂颗粒之间不会密切接触，从而会存在碳材料。当将造孔剂通过刻蚀剂刻蚀后，之前颗粒 之间存在的碳材料形成碳支柱。By controlling the amount of pore-forming agent in this application, it is possible to prevent close contact between pore-forming agent particles and the presence of carbon materials. When the pore former is etched through an etchant, the carbon material previously present between the particles forms carbon pillars.
在一个具体实施方式中，所述造孔剂的平均粒径D50为50～500nm，例如可为50nm、100nm、150nm、200nm、250nm、300nm、350nm、400nm、450nm、500nm等，优选为50～200nm。所述多孔碳层的多孔的平均孔径不小于所述造孔剂的平均粒径D50。本申请的平均孔径可通过气体渗透法进行测量。In a specific embodiment, the average particle size D50 of the pore-forming agent is 50 to 500nm, for example, it can be 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, etc., preferably 50 to 500nm. 200nm. The average pore size of the porous carbon layer is not less than the average particle size D50 of the pore-forming agent. The average pore size of the present application can be measured by gas permeation method.
在一个具体实施方式中，所述致密碳层二的厚度为所述微米硅平均粒径D50的0.05％～1％，例如可为0.05％、0.07％、0.09％、0.1％、0.1％、0.15％、0.2％、0.25％、0.3％、0.35％、0.4％、0.45％、0.5％、0.55％、0.6％、0.65％、0.7％、0.75％、0.8％、0.85％、0.9％、0.95％、1％等，优选为0.1％～0.2％。致密碳层二包覆于多孔碳层之上，起到封闭多孔碳层、隔绝电解液的作用。如果厚度过小，会暴露出多孔碳层中的孔结构，从而使电解液能够渗入，使各包覆层结构丧失原来的功能；如果厚度过大会降低复合材料的库伦效率。本申请的致密碳层二的厚度可以通过透射电镜进行多点测量取平均值得到，例如可为2个点、3个点、4个点、5个点、6个点、7个点、8个点、9个点、10个点等。In a specific embodiment, the thickness of the second dense carbon layer is 0.05% to 1% of the average particle diameter D50 of micron silicon, for example, it can be 0.05%, 0.07%, 0.09%, 0.1%, 0.1%, 0.15 %, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, etc., preferably 0.1% to 0.2%. The second dense carbon layer is coated on the porous carbon layer, which plays the role of closing the porous carbon layer and isolating the electrolyte. If the thickness is too small, the pore structure in the porous carbon layer will be exposed, allowing the electrolyte to penetrate, causing each coating layer structure to lose its original function; if the thickness is too large, the Coulombic efficiency of the composite material will be reduced. The thickness of the dense carbon layer 2 of the present application can be obtained by measuring multiple points through a transmission electron microscope and taking the average value. For example, it can be 2 points, 3 points, 4 points, 5 points, 6 points, 7 points, 8 points. points, 9 points, 10 points, etc.
在一个具体实施方式中，所述致密碳层二的孔隙率为5％～30％，例如可为5％、7％、9％、10％、12％、14％、16％、18％、20％、22％、24％、26％、28％、30％等，优选为5％～25％。致密碳层二与内部的两层包覆层协同作用，起到缓解微米硅膨胀的作用，其在循环过程中是会受到微米硅膨胀的作用力的，如果孔隙率太高，则结构中的缺陷多，结构的屈服强度下降，会使循环过程中结构被破坏；同时致密碳层二也起到隔离电解液的作用，孔隙率过高将导致电解液的渗入，从而降低材料的电化学性能。本申请的致密碳层二的孔隙率例如可通过真密度测试仪进行测定。In a specific embodiment, the porosity of the second dense carbon layer is 5% to 30%, for example, it can be 5%, 7%, 9%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, etc., preferably 5% to 25%. The second dense carbon layer cooperates with the two inner coating layers to alleviate the expansion of micron silicon. It will be affected by the expansion of micron silicon during the cycle. If the porosity is too high, the structure will There are many defects, and the yield strength of the structure decreases, which will cause the structure to be destroyed during the cycle; at the same time, the dense carbon layer 2 also plays a role in isolating the electrolyte. Excessive porosity will lead to the penetration of the electrolyte, thereby reducing the electrochemical performance of the material. . The porosity of the dense carbon layer 2 of the present application can be measured, for example, by a true density tester.
在一个具体实施方式中，所述碳壳层的肖氏硬度为10～50HSD，例如可为20HSD、25HSD、30HSD、35HSD、40HSD、45HSD等，优选为25～40。本申请的碳壳层的肖氏硬度是指包括致密碳层一、多孔碳层和致密碳层二的碳壳层的肖氏硬度。本申请中的“肖氏硬度”是指材料硬度的一种测试和表示方法，使用肖氏硬度计进行测量，例如可将材料与粘结剂混合后进行压片，压力为颗粒不破碎时所能承受的最大压力(可用SEM进行观察并调节)，再用该片进行测量。肖氏硬度越小，表明材料的柔软性越好，表明孔结构的成 功构筑，但太小的肖氏硬度无法维持包覆层自身的结构及硅膨胀产生的应力，适当的肖氏硬度才能维持自身结构稳定及消化体积膨胀。In a specific embodiment, the Shore hardness of the carbon shell layer is 10-50HSD, for example, it can be 20HSD, 25HSD, 30HSD, 35HSD, 40HSD, 45HSD, etc., preferably 25-40. The Shore hardness of the carbon shell layer in this application refers to the Shore hardness of the carbon shell layer including dense carbon layer one, porous carbon layer and dense carbon layer two. "Shore hardness" in this application refers to a method of testing and expressing the hardness of materials. It is measured using a Shore hardness tester. For example, the material can be mixed with a binder and then pressed into tablets. The pressure is the limit when the particles are not broken. The maximum pressure it can withstand (can be observed and adjusted with SEM), and then measured using this piece. The smaller the Shore hardness, the better the softness of the material, indicating the successful construction of the pore structure. However, the Shore hardness that is too small cannot maintain the structure of the coating layer itself and the stress generated by silicon expansion. Only an appropriate Shore hardness can be maintained. Its own structure is stable and its digestion volume expands.
在一个具体实施方式中，所述核壳结构微米硅碳复合材料的真密度为1.2～2.1g/cc，例如可为1.2g/cc、1.3g/cc、1.4g/cc、1.5g/cc、1.6g/cc、1.7g/cc、1.8g/cc、1.9g/cc、2.0g/cc、2.1g/cc等，优选1.4～1.8g/cc。本申请中的“真密度”是指材料在绝对密实的状态下单位体积的固体物质的实际质量，即去除内部孔隙或者颗粒间的空隙后的密度。本申请的真密度使用粉末真密度测试仪进行测定，例如可将试料置于真密度测试仪中，用氦气作介质,在测量室逐渐加压到一个规定值，然后氦气膨胀进入膨胀室内，两个过程的平衡压力由仪器自动记录，根据质量守恒定律，通过标准球校准测量室和膨胀室的体积后，再确定试料的体积,计算出真密度。In a specific embodiment, the true density of the core-shell structure micron silicon carbon composite material is 1.2-2.1g/cc, for example, it can be 1.2g/cc, 1.3g/cc, 1.4g/cc, 1.5g/cc , 1.6g/cc, 1.7g/cc, 1.8g/cc, 1.9g/cc, 2.0g/cc, 2.1g/cc, etc., preferably 1.4 to 1.8g/cc. The “true density” in this application refers to the actual mass of solid matter per unit volume of the material in an absolutely dense state, that is, the density after removing internal pores or gaps between particles. The true density of this application is measured using a powder true density tester. For example, the sample can be placed in the true density tester, using helium as the medium, gradually pressurizing the measuring chamber to a specified value, and then the helium expands into the expansion chamber. In the room, the equilibrium pressure of the two processes is automatically recorded by the instrument. According to the law of conservation of mass, after calibrating the volumes of the measurement chamber and the expansion chamber through the standard ball, the volume of the sample is determined and the true density is calculated.
在一个具体实施方式中，所述碳壳层与内核的质量比为0.16～0.5:1，优选为0.22～0.36:1，例如可为0.16:1、0.18:1、0.2:1、0.22:1、0.28:1、0.3:1、0.32:1、0.36:1、0.38:1、0.4:1、0.42:1、0.46:1、0.48:1、0.5:1等。In a specific embodiment, the mass ratio of the carbon shell to the core is 0.16-0.5:1, preferably 0.22-0.36:1, for example, it can be 0.16:1, 0.18:1, 0.2:1, 0.22:1 , 0.28:1, 0.3:1, 0.32:1, 0.36:1, 0.38:1, 0.4:1, 0.42:1, 0.46:1, 0.48:1, 0.5:1, etc.
在一个具体实施方式中，所述致密碳层一、多孔碳层和致密碳层二的碳源可以完全相同，也可以完全不同，也可以不完全相同。本申请的碳源不作限定，可以为任何碳源，各层碳源例如可分别选自沥青、酚醛树脂、腐殖酸、单宁酸、聚合多巴胺、聚吡咯、甲烷和乙烷中的一种或两种以上，优选为分别选自沥青、酚醛树脂和腐殖酸中的一种或两种以上。In a specific embodiment, the carbon sources of the first dense carbon layer, the porous carbon layer and the second dense carbon layer may be exactly the same, may be completely different, or may not be exactly the same. The carbon source in this application is not limited and can be any carbon source. For example, the carbon source of each layer can be selected from one of asphalt, phenolic resin, humic acid, tannic acid, polymerized dopamine, polypyrrole, methane and ethane. Or two or more, preferably one or two or more selected from the group consisting of asphalt, phenolic resin and humic acid.
在一个具体实施方式中，所述致密碳层一的碳源选自沥青、酚醛树脂和腐殖酸中的一种或两种以上；和/或，所述多孔碳层的碳源选自沥青、酚醛树脂和腐殖酸中的一种或两种以上；和/或，所述致密碳层二的碳源选自沥青、酚醛树脂和腐殖酸中的一种或两种以上。In a specific embodiment, the carbon source of the dense carbon layer I is selected from one or more of asphalt, phenolic resin and humic acid; and/or the carbon source of the porous carbon layer is selected from asphalt. , one or more of phenolic resin and humic acid; and/or the carbon source of the dense carbon layer 2 is selected from one or more of asphalt, phenolic resin and humic acid.
2.核壳结构微米硅碳复合材料制备方法2. Preparation method of core-shell structure micron silicon-carbon composite materials
本申请的发明人发现，采用下述制备方法可以简便地制备本申请的核壳结构微米硅碳复合材料。因此，另一方面，本申请还提供一种核壳结构微米硅碳复合材料的制备方法，其包括下述步骤：The inventor of the present application found that the core-shell structure micron silicon-carbon composite material of the present application can be easily prepared by using the following preparation method. Therefore, on the other hand, this application also provides a method for preparing a core-shell structure micron silicon-carbon composite material, which includes the following steps:
使用碳源一对微米硅进行包覆，得到包括微米硅和致密碳层一的复合颗粒一；Use a carbon source to coat a pair of micron silicon to obtain a composite particle 1 including micron silicon and a dense carbon layer 1;
使用碳源二和造孔剂对所述复合颗粒一进行包覆，得到复合颗粒二；Use carbon source two and a pore-forming agent to coat the composite particle one to obtain composite particle two;
将所述复合颗粒二分散于刻蚀剂中，得到包括微米硅、致密碳层一和多孔碳层的复合颗粒三；Disperse the composite particle 2 in an etchant to obtain a composite particle 3 including micron silicon, dense carbon layer 1 and porous carbon layer;
使用碳源三对所述复合颗粒三进行包覆，烧结，得到包括微米硅、致密碳层一、多孔碳层和致密碳层二的核壳结构微米硅碳复合材料。The composite particle three is coated with carbon source three and sintered to obtain a core-shell structure micron silicon-carbon composite material including micron silicon, dense carbon layer one, porous carbon layer and dense carbon layer two.
在一个具体实施方式中，本申请的核壳结构微米硅碳复合材料的制备方法包括下述步骤：In a specific embodiment, the preparation method of the core-shell structure micron silicon carbon composite material of the present application includes the following steps:
使用碳源一对微米硅进行包覆，得到包括微米硅和致密碳层一的复合颗粒一；Use a carbon source to coat a pair of micron silicon to obtain a composite particle 1 including micron silicon and a dense carbon layer 1;
使用碳源二和造孔剂对所述复合颗粒一进行包覆，烧结，得到复合颗粒二；Use carbon source two and a pore-forming agent to coat the composite particle one and sinter to obtain composite particle two;
将所述复合颗粒二分散于刻蚀剂中，得到包括微米硅、致密碳层一和多孔碳层的复合颗粒三；Disperse the composite particle 2 in an etchant to obtain a composite particle 3 including micron silicon, dense carbon layer 1 and porous carbon layer;
使用碳源三对所述复合颗粒三进行包覆，烧结，得到包括微米硅、致密碳层一、多孔碳层和致密碳层二的核壳结构微米硅碳复合材料。The composite particle three is coated with carbon source three and sintered to obtain a core-shell structure micron silicon-carbon composite material including micron silicon, dense carbon layer one, porous carbon layer and dense carbon layer two.
本申请对刻蚀剂的刻蚀时间不做具体限定，刻蚀剂过量即可。This application does not specifically limit the etching time of the etchant, as long as the etchant is excessive.
在一个具体实施方式中，在一个具体实施方式中，使用所述碳源二对微米硅进行包覆后再烧结的烧结温度为700～1000℃，例如可为700℃、720℃、740℃、760℃、780℃、800℃、820℃、840℃、860℃、880℃、900℃、920℃、940℃、960℃、980℃、1000℃等，优选为800～900℃，优选使用碳源二对微米硅进行包覆后再烧结的烧结时间为1～3h。In a specific embodiment, the sintering temperature for coating micron silicon with the second carbon source and then sintering is 700 to 1000°C, for example, it can be 700°C, 720°C, 740°C, 760℃, 780℃, 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 920℃, 940℃, 960℃, 980℃, 1000℃, etc., preferably 800~900℃, preferably using carbon Source 2 coats the micron silicon and then sinters the sintering time for 1 to 3 hours.
在一个具体实施方式中，使用碳源三对所述复合颗粒三进行包覆后再烧结的烧结温度为600～1100℃，例如可为600℃、620℃、640℃、660℃、680℃、700℃、720℃、740℃、760℃、780℃、800℃、820℃、840℃、860℃、880℃、900℃、920℃、940℃、960℃、980℃、1000℃、1020℃、1040℃、1060℃、1080℃、1100℃等，优选为700～1000℃，优选使用碳源三对所述复合颗粒三进行包覆后再烧结的烧结时间为2～6h。In a specific embodiment, the sintering temperature for coating the composite particles three with carbon source three and then sintering is 600 to 1100°C, for example, it can be 600°C, 620°C, 640°C, 660°C, 680°C, 700℃, 720℃, 740℃, 760℃, 780℃, 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 920℃, 940℃, 960℃, 980℃, 1000℃, 1020℃ , 1040°C, 1060°C, 1080°C, 1100°C, etc., preferably 700 to 1000°C, and the sintering time for coating the composite particles three with carbon source three and then sintering is preferably 2 to 6 hours.
本申请中对烧结装置没有限定，可以使用任何能够通入气氛、烧结升温的装置，例如可为干式回转窑、电热炉、管式炉、箱式炉、辊道窑等，又例如可使用氧-乙炔火焰、氧-氢火焰等烧结。There is no limit to the sintering device in this application. Any device that can pass into the atmosphere and heat up the sintering can be used. For example, it can be a dry rotary kiln, an electric furnace, a tube furnace, a box furnace, a roller kiln, etc. For example, it can be used Oxygen-acetylene flame, oxygen-hydrogen flame, etc. sintering.
在一个具体实施方式中，本申请的烧结在惰性气体下进行，本申请的惰性气氛可以不做限制，可以为任何惰性气氛，如氮气或氩气等。In a specific embodiment, the sintering of the present application is performed under an inert gas. The inert atmosphere of the present application is not limited and can be any inert atmosphere, such as nitrogen or argon.
在一个具体实施方式中，所述包覆为固相包覆，例如可采用机械融合机进行固相包覆。In a specific embodiment, the coating is solid phase coating. For example, a mechanical fusion machine can be used for solid phase coating.
在一个具体实施方式中，所述多孔碳层和致密碳层二均为固相包覆，所述致密碳层一可为固相包覆、气相包覆或液相包覆，优选所述致密碳层一为固相包覆。In a specific embodiment, both the porous carbon layer and the dense carbon layer are solid phase coatings, and the dense carbon layer one can be solid phase coating, gas phase coating, or liquid phase coating. Preferably, the dense carbon layer The first carbon layer is solid phase coating.
在一个具体实施方式中，所述烧结后包括降温。In a specific embodiment, the sintering includes cooling.
在一个具体实施方式中，所述核壳结构微米硅碳复合材料的制备方法中，将所述复合颗粒二分散于刻蚀剂中，搅拌后抽滤，清洗，烘干，得到包括微米硅、致密碳层一和多孔碳层的复合颗粒三。In a specific embodiment, in the preparation method of the core-shell structure micron silicon carbon composite material, the composite particles are dispersed in an etchant, stirred, filtered, washed, and dried to obtain micron silicon, Composite particles of dense carbon layer one and porous carbon layer three.
又一方面，本申请还提供一种由前述任一种制备方法制得的核壳结构微米硅碳复合材料。On the other hand, the present application also provides a core-shell structure micron silicon-carbon composite material prepared by any of the aforementioned preparation methods.
3.微米硅3. Micron silicon
本申请的核壳结构微米硅碳复合材料中，或本申请的核壳结构微米硅碳复合材料的制备方法中，所述微米硅可为晶态硅，也可为非晶态硅包覆晶态硅的球形微米硅。In the core-shell structure micron silicon-carbon composite material of the present application, or in the preparation method of the core-shell structure micron silicon-carbon composite material of the present application, the micron silicon can be crystalline silicon or amorphous silicon-coated crystal. Spherical micron silicon in the state of silicon.
3.1.晶态微米硅3.1. Crystalline micron silicon
本申请的晶态微米硅的平均粒径D50为1～8μm，例如可为1μm、1.5μm、2μm、2.5μm、3μm、3.5μm、4μm、4.5μm、5μm、5.5μm、6μm、6.5μm、7μm、7.5μm、8μm等，球形度为0.3～0.8，例如可为0.3、0.31、0.32、0.33、034、0.35、0.36、0.37、0.38、0.39、0.4、0.41、0.42、0.43、0.44、0.45、0.45、0.46、0.47、0.48、0.49、0.5、0.51、0.52、0.53、0.54、0.55、0.56、0.57、0.58、0.59、0.6、0.61、0.62、0.63、0.64、0.65、0.66、0.67、0.68、0.69、0.7、0.71、0.72、0.73、0.74、0.75、0.76、0.77、0.78、0.79、0.8等。The average particle diameter D50 of the crystalline micron silicon of the present application is 1 to 8 μm, for example, it can be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7μm, 7.5μm, 8μm, etc., the sphericity is 0.3~0.8, for example, it can be 0.3, 0.31, 0.32, 0.33, 034, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.45, 0.46, 0.48, 0.48, 0.5, 0.51, 0.52, 0.54, 0.55, 0.57, 0.58, 0.59, 0.62, 0.64, 0.66, 0.67, 0.68, 0.69, 0.68, 0.69, 0.68, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.69, 0.68, 0.69, 0.68, 0.69, 0.68, 0.69, 0.68, 0.699, 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.8, etc.
3.2.球形微米硅3.2. Spherical micron silicon
本申请的球形微米硅的内部为晶态硅，表面为非晶态硅，所述球形微米硅的平均粒径D50为1～8μm，例如可为1μm、1.5μm、2μm、2.5μm、3μm、3.5μm、4μm、4.5μm、5μm、5.5μm、6μm、6.5μm、7μm、7.5μm、8μm等，球形度为0.7～0.95，例如可为0.7、0.71、0.72、0.73、0.74、0.75、0.76、0.77、0.78、0.79、0.80、0.81、0.82、0.83、0.84、0.85、0.86、0.87、0.88、0.89、0.90、0.91、0.92、0.93、0.94、0.95等。The interior of the spherical micron silicon in this application is crystalline silicon and the surface is amorphous silicon. The average particle size D50 of the spherical micron silicon is 1 to 8 μm, for example, it can be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, etc., the sphericity is 0.7~0.95, for example, it can be 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, etc.
现有技术的微米硅为表面具有很多棱角的无规则形状晶态硅，晶态硅各向异性，各向膨胀异性，在硅嵌锂过程中，各向异性的体积膨胀容易在棱角处发生失效或破坏颗粒完整性。本申请的球形微米硅，表面具有一定厚度的非晶态硅，非晶硅各向同性，各向膨胀同向，使得球形微米硅对其外侧包覆层的各向作用力均匀，有利于维持电化学过程中的颗粒结构稳定性。Micron silicon in the existing technology is irregularly shaped crystalline silicon with many edges and corners on the surface. Crystalline silicon has anisotropy and anisotropic expansion. During the silicon lithium insertion process, anisotropic volume expansion easily causes failure at the edges and corners. or destroy particle integrity. The spherical micron silicon in this application has a certain thickness of amorphous silicon on the surface. The amorphous silicon is isotropic and expands in the same direction, so that the spherical micron silicon exerts uniform force on its outer coating layer in all directions, which is beneficial to maintaining the Particle structural stability during electrochemical processes.
在一个具体实施方式中，本申请的球形微米硅的平均粒径D50为2～5μm；球形微米硅的球形度为0.8～0.95。In a specific embodiment, the average particle size D50 of the spherical micron silicon of the present application is 2 to 5 μm; the sphericity of the spherical micron silicon is 0.8 to 0.95.
在一个具体实施方式中，本申请的球形微米硅的比表面积为0.5～5m 2/g，例如可为0.5m 2/g、1m 2/g、1.5m 2/g、2m 2/g、2.5m 2/g、3m 2/g、3.5m 2/g、4m 2/g、4.5m 2/g、5m 2/g等，优选为1～4m 2/g。 In a specific embodiment, the specific surface area of the spherical micron silicon of the present application is 0.5-5m 2 /g, for example, it can be 0.5m 2 /g, 1m 2 /g, 1.5m 2 /g, 2m 2 / g, 2.5 m 2 /g, 3m 2 / g, 3.5m 2 /g, 4m 2 /g, 4.5m 2 /g, 5m 2 /g, etc., preferably 1 to 4m 2 /g.
本申请的球形微米硅的比表面积可以通过实施例中给出的具体方法检测，利用BET比表面测试仪进行测定。The specific surface area of the spherical micron silicon of the present application can be detected by the specific method given in the embodiment, and measured using the BET specific surface tester.
本申请的球形微米硅粒径分布适中，球形度高，这样的结构优势使其具有较低的比表面积、较高的颗粒流动性以及较高的振实密度，进而使后续工艺难度降低，有利于维持电化学过程中的颗粒结构稳定性。The spherical micron silicon particle size distribution of the present application is moderate and the sphericity is high. Such structural advantages enable it to have a lower specific surface area, higher particle fluidity and higher tap density, thereby reducing the difficulty of subsequent processes and having It is beneficial to maintain the stability of the particle structure during the electrochemical process.
在一个具体实施方式中，本申请的球形微米硅中的非晶态硅的厚度为1～20nm，例如可为1nm、2nm、3nm、4nm、5nm、6nm、7nm、8nm、9nm、10nm、11nm、12nm、13nm、14nm、15nm、16nm、17nm、18nm、19nm、20nm等，优选为2～10nm，非晶态硅的厚度例如可通过透射电镜进行多点测量取平均值得到，例如可为2个点、3个点、4个点、5个点、6个点、7个点、8个点、9个点、10个点等。In a specific embodiment, the thickness of the amorphous silicon in the spherical micron silicon of the present application is 1 to 20nm, for example, it can be 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 11nm , 12nm, 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm, 20nm, etc., preferably 2 to 10nm. The thickness of amorphous silicon can be obtained by averaging multiple measurements through a transmission electron microscope, for example, it can be 2 points, 3 points, 4 points, 5 points, 6 points, 7 points, 8 points, 9 points, 10 points, etc.
本申请的球形微米硅的结构如图2的TEM图所示，图中左侧可见晶格条纹的部分为球形微米硅内部的晶态硅5；右侧无晶条格纹的部分为球形微米硅外层的非晶态硅6。在一个具体实施方式中，如图2所示，外层的非晶态硅厚度为10nm。The structure of the spherical micron silicon of the present application is shown in the TEM picture of Figure 2. The part with visible lattice stripes on the left side of the figure is the crystalline silicon 5 inside the spherical micron silicon; the part without the lattice stripes on the right side is the spherical micron silicon. Amorphous silicon 6 in the outer layer of silicon. In a specific embodiment, as shown in Figure 2, the thickness of the amorphous silicon in the outer layer is 10 nm.
3.3.球形微米硅的制备方法3.3. Preparation method of spherical micron silicon
本申请可以通过下述方法简便地制备本申请的球形微米硅，所述方法包括下述步骤：This application can simply prepare the spherical micron silicon of this application through the following method, which method includes the following steps:
将晶态微米硅在惰性气氛下烧结、保温、降温和破碎，得到球形微米硅。The crystalline micron silicon is sintered, kept warm, cooled and crushed under an inert atmosphere to obtain spherical micron silicon.
这里，晶态微米硅为现有技术的晶态微米硅。在一个具体实施方式中，所述晶态微米硅的平均粒径D50为1～8μm，例如可为1μm、1.5μm、2μm、 2.5μm、3μm、3.5μm、4μm、4.5μm、5μm、5.5μm、6μm、6.5μm、7μm、7.5μm、8μm等，所述晶态微米硅的球形度为0.3～0.7，例如可为0.3、0.35、0.4、0.45、0.5、0.55、0.6、0.65、0.7等。本申请的球形微米硅的平均粒径D50小于或等于所述晶态微米硅的平均粒径D50，本申请的球形微米硅的球形度大于晶态微米硅的球形度。Here, the crystalline micron silicon is crystalline micron silicon of the related art. In a specific embodiment, the average particle size D50 of the crystalline micron silicon is 1 to 8 μm, for example, it can be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, or 5.5 μm. , 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, etc., the sphericity of the crystalline micron silicon is 0.3 to 0.7, for example, it can be 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, etc. The average particle size D50 of the spherical micron silicon of the present application is less than or equal to the average particle size D50 of the crystalline micron silicon. The sphericity of the spherical micron silicon of the present application is greater than the sphericity of the crystalline micron silicon.
这里，惰性气氛可以不做限制，可以为任何惰性气氛，如氮气或氩气等。Here, the inert atmosphere is not limited and can be any inert atmosphere, such as nitrogen or argon.
在一个具体实施方式中，所述烧结温度为1300～1600℃，例如可为1300℃、1310℃、1320℃、1330℃、1340℃、1350℃、1360℃、1370℃、1380℃、1390℃、1400℃、1410℃、1420℃、1430℃、144℃、1450℃、1460℃、1470℃、1480℃、1490℃、1500℃、1510℃、1520℃、1530℃、1540℃、1550℃、1560℃、1570℃、1580℃、1590℃、1600℃等，优选为1400～1500℃。将温度升至晶体硅的熔点附近，由于棱角处的反应活性高于本体，所以棱角处先发生熔融，从而棱角处的硅材料由于表面张力的作用发生重组或转移，从而棱角转变为圆滑结构，球形度增大。本申请中对烧结装置没有限定，可以使用任何能够烧结升温的装置，例如可为干式回转窑、电热炉、管式炉、箱式炉、辊道窑等，又例如可使用氧-乙炔火焰、氧-氢火焰等烧结。In a specific embodiment, the sintering temperature is 1300-1600°C, for example, it can be 1300°C, 1310°C, 1320°C, 1330°C, 1340°C, 1350°C, 1360°C, 1370°C, 1380°C, 1390°C, 1400℃, 1410℃, 1420℃, 1430℃, 144℃, 1450℃, 1460℃, 1470℃, 1480℃, 1490℃, 1500℃, 1510℃, 1520℃, 1530℃, 1540℃, 1550℃, 1560℃ , 1570°C, 1580°C, 1590°C, 1600°C, etc., preferably 1400 to 1500°C. When the temperature is raised to near the melting point of crystalline silicon, since the reactivity at the corners is higher than that of the bulk, the corners melt first, and the silicon material at the corners is reorganized or transferred due to the surface tension, and the corners are transformed into a smooth structure. Increased sphericity. There is no limit to the sintering device in this application. Any device capable of heating up sintering can be used. For example, it can be a dry rotary kiln, an electric furnace, a tube furnace, a box furnace, a roller kiln, etc., and for example, an oxygen-acetylene flame can be used. , oxygen-hydrogen flame and other sintering.
在一个具体实施方式中，以1～10℃/min、优选为3～6℃/min的升温速率升温至所述烧结温度，所述升温速率例如可为1℃/min、1.5℃/min、2℃/min、2.5℃/min、3℃/min、3.5℃/min、4℃/min、4.5℃/min、5℃/min、5.5℃/min、6℃/min、6.5℃/min、7℃/min、7.5℃/min、8℃/min、8.5℃/min、9℃/min、9.5℃/min、10℃/min等。In a specific embodiment, the temperature is raised to the sintering temperature at a heating rate of 1 to 10°C/min, preferably 3 to 6°C/min. The heating rate can be, for example, 1°C/min, 1.5°C/min, 2℃/min, 2.5℃/min, 3℃/min, 3.5℃/min, 4℃/min, 4.5℃/min, 5℃/min, 5.5℃/min, 6℃/min, 6.5℃/min, 7℃/min, 7.5℃/min, 8℃/min, 8.5℃/min, 9℃/min, 9.5℃/min, 10℃/min, etc.
在一个具体实施方式中，所述烧结温度高于1300℃，当升温至1300℃时，开始以3～6℃/min的升温速率升温至所述烧结温度。当升温至1300℃时需要调整升温速率使之不至于过快，避免硅棱角的快速融化导致颗粒发生黏连，虽然黏连可通过破碎打开，但是破碎过程可能又会造出棱角。In a specific embodiment, the sintering temperature is higher than 1300°C. When the temperature rises to 1300°C, the temperature starts to rise to the sintering temperature at a heating rate of 3 to 6°C/min. When the temperature rises to 1300°C, the heating rate needs to be adjusted so that it is not too fast to avoid the rapid melting of the silicon edges and the adhesion of the particles. Although the adhesion can be opened by crushing, the crushing process may create edges and corners.
在一个具体实施方式中，所述保温时间为0.5～10h，例如可为0.5h、1h、1.5h、2h、2.5h、3h、3.5h、4h、4.5h、5h、5.5h、6h、6.5h、7h、7.5h、8h、8.5h、9h、9.5h、10h等，优选为0.5～4h。保温时间过短，棱角未充分熔融，球形度不高；保温时间过长，棱角充分熔融并可能在颗粒将发生接触转移，导致黏连。In a specific embodiment, the holding time is 0.5-10h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5 h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, etc., preferably 0.5 to 4h. If the heat preservation time is too short, the edges and corners are not fully melted, and the sphericity is not high; if the heat preservation time is too long, the edges and corners are fully melted and may cause contact transfer between the particles, resulting in adhesion.
在一个具体实施方式中，所述降温速率为10～100℃/min，例如可为 10℃/min、15℃/min、20℃/min、25℃/min、30℃/min、35℃/min、40℃/min、45℃/min、50℃/min、55℃/min、60℃/min、65℃/min、70℃/min、75℃/min、80℃/min、85℃/min、90℃/min、95℃/min、100℃/min等，优选为50～80℃/min。控制降温速率，晶型位错，形成一层非晶态硅，将降温速率控制在10～100℃/min，可使非晶态硅的厚度达到1～20nm。本申请中对降温装置没有限定，可以使用任何能够降温的装置，例如可为吹扫低温惰性气氛的方式。In a specific embodiment, the cooling rate is 10-100°C/min, for example, it can be 10°C/min, 15°C/min, 20°C/min, 25°C/min, 30°C/min, 35°C/min. min, 40℃/min, 45℃/min, 50℃/min, 55℃/min, 60℃/min, 65℃/min, 70℃/min, 75℃/min, 80℃/min, 85℃/ min, 90°C/min, 95°C/min, 100°C/min, etc., preferably 50 to 80°C/min. Controlling the cooling rate, crystal dislocations form a layer of amorphous silicon. Controlling the cooling rate at 10-100°C/min can make the thickness of amorphous silicon reach 1-20nm. There is no limit to the cooling device in this application, and any device capable of cooling can be used, for example, it can be a method of purging a low-temperature inert atmosphere.
本申请的包括球形微米硅的核壳结构复合材料应用于锂离子电池中时，球形微米硅各向同性膨胀，其球形结构提高了表面包覆的连续性，膨胀时包覆层的受力均匀，复合材料克服了微米硅的巨大膨胀效应，从而降低了电池在循环过程中的形变，提高电池的安全性能。同时复合材料在循环过程中保持结构稳定性，避免了界面不可逆SEI膜的生长、电解液的渗入，从而提高电池的循环性能。When the core-shell structure composite material including spherical micron silicon of the present application is used in a lithium-ion battery, the spherical micron silicon expands isotropically, and its spherical structure improves the continuity of the surface coating, and the coating layer is evenly stressed during expansion. , the composite material overcomes the huge expansion effect of micron silicon, thereby reducing the deformation of the battery during cycling and improving the safety performance of the battery. At the same time, the composite material maintains structural stability during the cycle, avoiding the growth of the irreversible SEI film at the interface and the infiltration of electrolyte, thus improving the cycle performance of the battery.
4.电极4.Electrode
另一方面，本申请还提供一种电极，本申请的电极包括电极集流体和涂覆在所述电极集流体上的电极活性物质层，所述电极活性物质层至少包含球形微米硅作为电极活性物质，其中所述球形微米硅是前述任一种球形微米硅或采用本申请的前述任一种制备方法制备的球形微米硅。所述电极活性物质层还可包含本申请前述任一种核壳结构复合材料。本申请的电极优选为负极。On the other hand, the present application also provides an electrode. The electrode of the present application includes an electrode current collector and an electrode active material layer coated on the electrode current collector. The electrode active material layer at least contains spherical micron silicon as the electrode active material. Substance, wherein the spherical micron silicon is any of the aforementioned spherical micron silicon or spherical micron silicon prepared by any of the foregoing preparation methods of the present application. The electrode active material layer may also include any of the core-shell structure composite materials mentioned above in this application. The electrode of the present application is preferably a negative electrode.
4.1.电极活性物质4.1.Electrode active material
本申请的电极活性物质可以负极活性物质，对其并无特殊限制，可以使用本技术领域通常使用的负极活性物质。The electrode active material of the present application can be a negative electrode active material, which is not particularly limited, and negative electrode active materials commonly used in this technical field can be used.
优选地，所述电极活性物质以本申请的球形微米硅作为主成分。Preferably, the electrode active material uses the spherical micron silicon of the present application as the main component.
对除本申请的球形微米硅以外，所述电极活性物质层还可以包含其他电极活性物质。以下，对其他电极活性物质进行说明。In addition to the spherical micron silicon of the present application, the electrode active material layer may also contain other electrode active materials. Next, other electrode active materials will be described.
作为负极活性物质，可以列举出例如：作为高结晶性碳的石墨(天然石墨、人造石墨等)、低结晶性碳(软碳)、硬碳、炭黑(Ketjen Black(注册商标)、乙炔黑、槽法炭黑、灯黑、油炉法炭黑、热裂炭黑等)、富勒烯、碳纳米管、碳纳米纤维、碳纳米突、碳纤丝等碳材料。此外，作为负极活性物质，还可以列举出Si、Ge、Sn、Pb、Al、In、Zn、H、Ca、Sr、Ba、Ru、Rh、Ir、Pd、Pt、Ag、Au、Cd、Hg、Ga、Tl、C、N、Sb、Bi、O、S、Se、Te、Cl等与 锂发生合金化的元素的单质、包含这些元素的氧化物及碳化物等。作为这样的氧化物，可以列举出一氧化硅(SiO)、SiO x(0<x<2)、二氧化锡(SnO 2)、SnO x(0<x<2)、SnSiO 3等，作为碳化物，可以列举出碳化硅(SiC)等。此外，作为负极活性物质，还可以列举出锂金属等金属材料、锂-钛复合氧化物(例如钛酸锂Li 4Ti 5O 12)等锂-过渡金属复合氧化物。但并不限定于这些材料，可以使用可被用作锂离子电池用负极活性物质的传统公知的材料。这些负极活性物质可以仅单独使用一种，也可以将两种以上组合使用。 Examples of the negative electrode active material include highly crystalline carbon graphite (natural graphite, artificial graphite, etc.), low crystalline carbon (soft carbon), hard carbon, carbon black (Ketjen Black (registered trademark), acetylene black , channel carbon black, lamp black, oil furnace carbon black, thermal carbon black, etc.), fullerene, carbon nanotubes, carbon nanofibers, carbon nanohorns, carbon filaments and other carbon materials. In addition, examples of negative electrode active materials include Si, Ge, Sn, Pb, Al, In, Zn, H, Ca, Sr, Ba, Ru, Rh, Ir, Pd, Pt, Ag, Au, Cd, and Hg. , Ga, Tl, C, N, Sb, Bi, O, S, Se, Te, Cl and other elements that are alloyed with lithium, as well as oxides and carbides containing these elements. Examples of such oxides include silicon monoxide (SiO), SiO x (0<x<2), tin dioxide (SnO 2 ), SnO x (0<x<2), SnSiO 3 , etc., as carbonized Materials include silicon carbide (SiC), etc. Examples of the negative electrode active material include metal materials such as lithium metal and lithium-transition metal composite oxides such as lithium-titanium composite oxides (for example, lithium titanate Li 4 Ti 5 O 12 ). However, the material is not limited to these materials, and conventionally known materials that can be used as negative electrode active materials for lithium ion batteries can be used. Only one type of these negative electrode active materials may be used alone, or two or more types may be used in combination.
4.2.电极集流体4.2.Electrode current collector
本申请的电极集流体可为负极集流体，其由导电性材料构成。对电极集流体的厚度没有特殊限制。电极集流体的厚度通常为0.1～1000μm左右、优选1～100μm左右。对于电极集流体的形状没有特别地限定。对构成电极集流体的材料没有特殊限制。例如，可以为铜。The electrode current collector of the present application may be a negative electrode current collector, which is made of conductive material. There is no particular limit on the thickness of the electrode current collector. The thickness of the electrode current collector is usually about 0.1 to 1000 μm, preferably about 1 to 100 μm. The shape of the electrode current collector is not particularly limited. The material constituting the electrode current collector is not particularly limited. For example, it can be copper.
4.3.电极4.3.Electrode
可以采用传统公知的方法在所述电极集流体上形成所述活性物质层来制备所述电极，但不限于此。本领域技术人员可以根据所要制造的电池的类型，来选择合适的方法制造电极。The electrode may be prepared by forming the active material layer on the electrode current collector using conventionally known methods, but is not limited thereto. Those skilled in the art can select a suitable method to manufacture electrodes according to the type of battery to be manufactured.
使用电极活性物质的电极的制造可利用常规方法进行。即，可以将电极活性物质和导电剂、以及根据需要而使用的粘结剂及增稠剂等进行干式混合并制成片状，再将该片状材料压合在电极集流体上，或将这些材料溶解或分散在液体介质中制成浆料，将该浆料涂布于电极集流体上并进行干燥，由此在电极集流体上形成电极活性物质层，从而得到电极。The electrode using the electrode active material can be produced by a conventional method. That is, the electrode active material and the conductive agent, as well as the binder and thickener used as needed, can be dry-mixed into a sheet, and the sheet-shaped material can be pressed onto the electrode current collector, or These materials are dissolved or dispersed in a liquid medium to form a slurry, and the slurry is applied to an electrode current collector and dried to form an electrode active material layer on the electrode current collector, thereby obtaining an electrode.
作为导电剂，其可以包含任何可用作导电剂的其它成分。例如，还可以包含：铜、镍等金属材料；天然石墨、人造石墨等石墨(graphite)；乙炔黑等炭黑；针状焦等无定形碳等碳材料等。这些导电剂可以单独使用一种，也可以以任意组合及比例将两种以上组合使用。As the conductive agent, it may contain any other component that can be used as a conductive agent. For example, it may also include metal materials such as copper and nickel; graphite such as natural graphite and artificial graphite; carbon black such as acetylene black; and carbon materials such as amorphous carbon such as needle coke. These conductive agents may be used alone or in combination of two or more in any combination and ratio.
此外，所述电极活性物质层还可以包含粘结剂。作为用于制造电极活性物质层的粘结剂，并无特殊限制，采用涂布法的情况下，只要是可溶解或分散于制造电极时所使用的液体介质中的材料即可。In addition, the electrode active material layer may further contain a binder. There is no particular restriction on the binder used to produce the electrode active material layer. When a coating method is used, it may be a material that can be dissolved or dispersed in the liquid medium used in producing the electrode.
作为用于形成浆料的溶剂，只要是可以溶解或分散电极活性物质、导电剂、粘结剂、以及根据需要而使用的增稠剂的溶剂即可，对其种类没有特殊限制，可以使用水性溶剂和有机类溶剂中的任意溶剂。The solvent used to form the slurry is not particularly limited as long as it can dissolve or disperse the electrode active material, the conductive agent, the binder and, if necessary, the thickener. Water-based solvents can be used. Solvents and any solvent in organic solvents.
增稠剂通常可用于调节浆料的粘度。所述电极活性物质层中还可以包含增稠剂。作为增稠剂，并无特殊限制。Thickeners are often used to adjust the viscosity of the slurry. The electrode active material layer may also contain a thickener. As a thickening agent, there are no particular restrictions.
5.电池5.Battery
本申请的电极可用于电池。因此，另一方面，本申请还提供一种电池，其包括正极、负极、隔膜和电解质，其中，所述负极是本申请前述的负极。The electrodes of this application can be used in batteries. Therefore, on the other hand, the present application also provides a battery, which includes a positive electrode, a negative electrode, a separator and an electrolyte, wherein the negative electrode is the aforementioned negative electrode of the present application.
在本申请中电池是指包括一个或多个电池单体以提供更高的电压和容量的单一的物理模块。例如，本申请中所提及的电池可以包括电池模块或电池包等。A battery in this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application may include a battery module or a battery pack.
本申请的电池单体可以包括锂离子二次电池、锂离子一次电池、锂硫电池、钠锂离子电池、钠离子电池和镁离子电池中的一种或两种以上，本申请对此并不限定。本申请的电池单体可呈圆柱体、扁平体、长方体或其它形状等，本申请实施例对此也不作限定。电池单体一般按封装的方式分成三种：圆柱电池单体、方形电池单体和软包电池单体，本申请并不限于此。The battery cells of this application may include one or more of lithium ion secondary batteries, lithium ion primary batteries, lithium sulfur batteries, sodium lithium ion batteries, sodium ion batteries and magnesium ion batteries. This application does not limited. The battery cell of the present application may be in the shape of a cylinder, a flat body, a rectangular parallelepiped or other shapes, and the embodiments of the present application are not limited to this. Battery cells are generally divided into three types according to packaging methods: cylindrical battery cells, prismatic battery cells and soft-pack battery cells. This application is not limited thereto.
所述隔膜通常配置在所述正极与负极之间。对隔膜的材料及形状没有特殊限制，可任意采用公知的隔膜。例如，可使用由树脂、玻璃纤维、无机物等，优选使用保液性优异的多孔片或无纺布状形态的材料等。The separator is usually disposed between the positive electrode and the negative electrode. There are no special restrictions on the material and shape of the separator, and any known separator can be used. For example, resins, glass fibers, inorganic substances, etc. can be used, and materials in the form of porous sheets or nonwoven fabrics that are excellent in liquid retention are preferably used.
电解质填充在所述正极和负极之间。所述电解质可以是水性电解质，也可以是非水电解质。此外，所述电解质可以是电解液、高分子凝胶电解质、固体高分子电解质。Electrolyte is filled between the positive and negative electrodes. The electrolyte may be an aqueous electrolyte or a non-aqueous electrolyte. In addition, the electrolyte may be an electrolyte, a polymer gel electrolyte, or a solid polymer electrolyte.
实施例Example
本申请对试验中所用到的材料以及试验方法进行一般性和/或具体的描述，在下面的实施例中，所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规试剂或仪器。This application provides a general and/or specific description of the materials and test methods used in the test. In the following examples, the reagents or instruments used are conventional reagents that can be purchased commercially if the manufacturer is not indicated. or instrument.
实施例1-1Example 1-1
按照以下步骤制备本实施例的球形微米硅：The spherical micron silicon of this embodiment is prepared according to the following steps:
将1kg D50为5μm、球形度为0.3的晶态微米硅在氮气气氛下以5℃/min升温至1400℃，保温5h后，以50℃/min的速率降温至室温，取出，破碎得到D50为4μm、球形度为0.8的球形微米硅。1kg of crystalline micron silicon with a D50 of 5 μm and a sphericity of 0.3 is heated to 1400°C at a rate of 5°C/min in a nitrogen atmosphere. After being kept for 5 hours, it is cooled to room temperature at a rate of 50°C/min. Take it out and crush it to obtain a D50 of 4μm, spherical micron silicon with a sphericity of 0.8.
实施例1-2Example 1-2
按照以下步骤制备本实施例的球形微米硅：The spherical micron silicon of this embodiment is prepared according to the following steps:
将1kgD50为6μm、球形度为0.5的晶态微米硅在氮气气氛下以10℃/min升温至1500℃，保温2h后，以100℃/min的速率降温至室温，取出，破碎得到D50为6μm、球形度为0.9的球形微米硅。1kg of crystalline micron silicon with a D50 of 6 μm and a sphericity of 0.5 is heated to 1500°C at 10°C/min in a nitrogen atmosphere. After being kept for 2 hours, it is cooled to room temperature at a rate of 100°C/min. Take it out and crush it to obtain a D50 of 6 μm. , spherical micron silicon with a sphericity of 0.9.
实施例1-3Example 1-3
按照以下步骤制备本实施例的球形微米硅：The spherical micron silicon of this embodiment is prepared according to the following steps:
将1kg D50为2μm、球形度为0.6的晶态微米硅在氮气气氛下以3℃/min升温至1400℃，保温4h后，以60℃/min的速率降温至室温，取出，破碎得到D50为2μm、球形度为0.95的球形微米硅。1kg of crystalline micron silicon with a D50 of 2 μm and a sphericity of 0.6 is heated to 1400°C at 3°C/min in a nitrogen atmosphere. After being kept for 4 hours, it is cooled to room temperature at a rate of 60°C/min, taken out, and crushed to obtain a D50 of 2μm spherical micron silicon with a sphericity of 0.95.
实施例1-4Examples 1-4
按照以下步骤制备本实施例的球形微米硅：The spherical micron silicon of this embodiment is prepared according to the following steps:
将1kgD50为4μm、球形度为0.3的晶态微米硅在氮气气氛下以5℃/min升温至1450℃，保温5h后，以80℃/min的速率降温至室温，取出，破碎得到D50为3μm、球形度为0.8的球形微米硅。1kg of crystalline micron silicon with a D50 of 4 μm and a sphericity of 0.3 is heated to 1450°C at a rate of 5°C/min in a nitrogen atmosphere. After incubation for 5 hours, it is cooled to room temperature at a rate of 80°C/min. Take it out and crush it to obtain a D50 of 3 μm. , spherical micron silicon with a sphericity of 0.8.
实施例1-5Examples 1-5
本实施例与实施例1-3的区别在于，烧结温度为1600℃。The difference between this embodiment and Examples 1-3 is that the sintering temperature is 1600°C.
实施例1-6Examples 1-6
本实施例与实施例1-3的区别在于，烧结温度为1300℃。The difference between this embodiment and Examples 1-3 is that the sintering temperature is 1300°C.
实施例1-7Example 1-7
本实施例与实施例1-3的区别在于，烧结温度为1500℃。The difference between this embodiment and Examples 1-3 is that the sintering temperature is 1500°C.
实施例1-8Example 1-8
本实施例与实施例1-3的区别在于，升温速率为1℃/min。The difference between this embodiment and Examples 1-3 is that the heating rate is 1°C/min.
实施例1-9Example 1-9
本实施例与实施例1-3的区别在于，升温速率为10℃/min。The difference between this embodiment and Examples 1-3 is that the heating rate is 10°C/min.
实施例1-10Examples 1-10
本实施例与实施例1-3的区别在于，保温时间为0.5h。The difference between this embodiment and Examples 1-3 is that the holding time is 0.5h.
实施例1-11Example 1-11
本实施例与实施例1-3的区别在于，保温时间为10h。The difference between this embodiment and Examples 1-3 is that the holding time is 10 hours.
实施例1-12Examples 1-12
本实施例与实施例1-3的区别在于，降温速率为10℃/min。The difference between this embodiment and Examples 1-3 is that the cooling rate is 10°C/min.
实施例1-13Examples 1-13
本实施例与实施例1-3的区别在于，降温速率为100℃/min。The difference between this embodiment and Examples 1-3 is that the cooling rate is 100°C/min.
实施例1-14Examples 1-14
本实施例与实施例3的区别在于，降温速率为50℃/min。The difference between this embodiment and Embodiment 3 is that the cooling rate is 50°C/min.
实施例1-15Examples 1-15
本实施例与实施例1-3的区别在于，降温速率为80℃/min。The difference between this embodiment and Examples 1-3 is that the cooling rate is 80°C/min.
将各实施例的参数条件、试剂、产品参数等列于下表1和2中：The parameter conditions, reagents, product parameters, etc. of each embodiment are listed in the following Tables 1 and 2:
表1Table 1
Figure PCTCN2022135031-appb-000002
Figure PCTCN2022135031-appb-000002
表2Table 2
Figure PCTCN2022135031-appb-000003
Figure PCTCN2022135031-appb-000003
实施例2-1Example 2-1
(1)取1kgD50为4μm、球形度为0.8的晶态微米硅与100g沥青混合均匀，置于机械融合机中进行包覆，得到复合颗粒一；(1) Take 1kg of crystalline micron silicon with a D50 of 4 μm and a sphericity of 0.8 and mix it evenly with 100g of asphalt, place it in a mechanical fusion machine for coating, and obtain composite particles 1;
(2)取100g沥青、300g D50为200nm的纳米氧化镁、1kg复合颗粒一混合均匀后，置于机械融合机中进行包覆后，在氮气气氛下烧结800℃保持4h，降温，得到复合颗粒二；(2) Take 100g of asphalt, 300g of nano-magnesium oxide with D50 of 200nm, and 1kg of composite particles. Mix them evenly, place them in a mechanical fusion machine for coating, and sinter them at 800°C for 4 hours in a nitrogen atmosphere. Then cool down to obtain composite particles. two;
(3)将复合颗粒二分散于盐酸中，搅拌4h后抽滤，清洗，烘干，得到复合颗粒三；(3) Disperse composite particle 2 in hydrochloric acid, stir for 4 hours, then filter, wash, and dry to obtain composite particle 3;
(4)将1kg复合颗粒三与50g沥青混合均匀，进行机械融合后，在氮气气氛下烧结800℃保持4h，得到核壳结构微米硅碳复合材料。(4) Mix 1kg of composite particles 3 and 50g of asphalt evenly, mechanically fuse, and then sinter at 800°C for 4 hours in a nitrogen atmosphere to obtain a core-shell structure micron silicon-carbon composite material.
得到的核壳结构微米硅碳复合材料中，致密碳层一的厚度为20nm，多孔碳层的厚度为1μm，致密碳层二的厚度为5nm。In the core-shell structure micron silicon-carbon composite material obtained, the thickness of the dense carbon layer one is 20 nm, the thickness of the porous carbon layer is 1 μm, and the thickness of the second dense carbon layer is 5 nm.
实施例2-2Example 2-2
本实施例与实施例2-1的区别在于，晶态微米硅的球形度为0.3。The difference between this embodiment and Embodiment 2-1 is that the sphericity of crystalline micron silicon is 0.3.
得到的核壳结构微米硅碳复合材料中，致密碳层一的厚度为14nm，多孔碳层的厚度为0.8μm，致密碳层二的厚度为4nm。In the core-shell structure micron silicon-carbon composite material obtained, the thickness of the dense carbon layer one is 14 nm, the thickness of the porous carbon layer is 0.8 μm, and the thickness of the second dense carbon layer is 4 nm.
实施例2-3Example 2-3
本实施例与实施例2-1的区别在于，晶态微米硅的D50为8μm。The difference between this embodiment and Embodiment 2-1 is that the D50 of crystalline micron silicon is 8 μm.
得到的核壳结构微米硅碳复合材料中，致密碳层一的厚度为12nm，多孔碳层的厚度为0.64μm，致密碳层二的厚度为3.2nm。In the core-shell structure micron silicon-carbon composite material obtained, the thickness of the dense carbon layer one is 12 nm, the thickness of the porous carbon layer is 0.64 μm, and the thickness of the second dense carbon layer is 3.2 nm.
实施例2-4Example 2-4
本实施例与实施例2-1的区别在于，造孔剂为纳米氧化铝。The difference between this embodiment and Embodiment 2-1 is that the pore-forming agent is nano-alumina.
得到的核壳结构微米硅碳复合材料中，致密碳层一的厚度为20nm，多孔碳层的厚度为0.92μm，致密碳层二的厚度为5nm。In the core-shell structure micron silicon-carbon composite material obtained, the thickness of the dense carbon layer one is 20 nm, the thickness of the porous carbon layer is 0.92 μm, and the thickness of the second dense carbon layer is 5 nm.
实施例2-5Example 2-5
本实施例与实施例2-1的区别在于，造孔剂的平均粒径D50为50nm。The difference between this embodiment and Example 2-1 is that the average particle size D50 of the pore-forming agent is 50 nm.
得到的核壳结构微米硅碳复合材料中，致密碳层一的厚度为20nm，多孔碳层的厚度为1.24μm，致密碳层二的厚度为3.6nm。In the core-shell structure micron silicon-carbon composite material obtained, the thickness of the dense carbon layer one is 20 nm, the thickness of the porous carbon layer is 1.24 μm, and the thickness of the second dense carbon layer is 3.6 nm.
实施例2-6Example 2-6
本实施例与实施例2-1的区别在于，造孔剂的平均粒径D50为500nm。The difference between this embodiment and Example 2-1 is that the average particle size D50 of the pore-forming agent is 500 nm.
得到的核壳结构微米硅碳复合材料中，致密碳层一的厚度为20nm，多孔碳层的厚度为0.76μm，致密碳层二的厚度为6nm。In the core-shell structure micron silicon-carbon composite material obtained, the thickness of the dense carbon layer one is 20 nm, the thickness of the porous carbon layer is 0.76 μm, and the thickness of the second dense carbon layer is 6 nm.
实施例2-7Example 2-7
本实施例与实施例2-1的区别在于，步骤(1)、(2)和(4)中的碳源均为酚醛树脂。The difference between this embodiment and Example 2-1 is that the carbon sources in steps (1), (2) and (4) are all phenolic resins.
得到的核壳结构微米硅碳复合材料中，致密碳层一的厚度为16nm，多孔碳层的厚度为0.68μm，致密碳层二的厚度为4nm。In the core-shell structure micron silicon-carbon composite material obtained, the thickness of the dense carbon layer one is 16 nm, the thickness of the porous carbon layer is 0.68 μm, and the thickness of the second dense carbon layer is 4 nm.
实施例2-8Example 2-8
本实施例与实施例2-1的区别在于，步骤(1)、(2)和(4)中的碳源均为腐殖酸。The difference between this embodiment and Example 2-1 is that the carbon sources in steps (1), (2) and (4) are all humic acid.
得到的核壳结构微米硅碳复合材料中，致密碳层一的厚度为16nm，多孔碳层的厚度为1.12μm，致密碳层二的厚度为6nm。In the core-shell structure micron silicon-carbon composite material obtained, the thickness of the dense carbon layer one is 16 nm, the thickness of the porous carbon layer is 1.12 μm, and the thickness of the second dense carbon layer is 6 nm.
实施例2-9Example 2-9
本实施例与实施例2-1的区别在于，纳米氧化镁为100g。The difference between this embodiment and Embodiment 2-1 is that the amount of nano-magnesium oxide is 100g.
得到的核壳结构微米硅碳复合材料中，致密碳层一的厚度为20nm，多孔碳层的厚度为0.2μm，致密碳层二的厚度为5nm。In the core-shell structure micron silicon-carbon composite material obtained, the thickness of the dense carbon layer one is 20 nm, the thickness of the porous carbon layer is 0.2 μm, and the thickness of the second dense carbon layer is 5 nm.
实施例2-10Example 2-10
本实施例与实施例2-1的区别在于，纳米氧化镁为250g。The difference between this embodiment and Embodiment 2-1 is that the amount of nano-magnesium oxide is 250g.
得到的核壳结构微米硅碳复合材料中，致密碳层一的厚度为20nm，多孔碳层的厚度为0.6μm，致密碳层二的厚度为5nm。In the core-shell structure micron silicon-carbon composite material obtained, the thickness of the dense carbon layer one is 20 nm, the thickness of the porous carbon layer is 0.6 μm, and the thickness of the second dense carbon layer is 5 nm.
实施例2-11Example 2-11
本实施例与实施例2-1的区别在于，步骤(2)和(4)烧结温度均为1000℃。The difference between this embodiment and Embodiment 2-1 is that the sintering temperatures in steps (2) and (4) are both 1000°C.
得到的核壳结构微米硅碳复合材料中，致密碳层一的厚度为18nm，多孔碳层的厚度为0.88μm，致密碳层二的厚度为4nm。In the core-shell structure micron silicon-carbon composite material obtained, the thickness of the dense carbon layer one is 18 nm, the thickness of the porous carbon layer is 0.88 μm, and the thickness of the second dense carbon layer is 4 nm.
实施例2-12Example 2-12
本实施例与实施例2-1的区别在于，步骤(2)和(4)烧结温度均为700℃。The difference between this embodiment and Embodiment 2-1 is that the sintering temperatures in steps (2) and (4) are both 700°C.
得到的核壳结构微米硅碳复合材料中，致密碳层一的厚度为24nm，多孔碳层的厚度为1.24μm，致密碳层二的厚度为7.2nm。In the core-shell structure micron silicon-carbon composite material obtained, the thickness of the dense carbon layer one is 24 nm, the thickness of the porous carbon layer is 1.24 μm, and the thickness of the second dense carbon layer is 7.2 nm.
实施例2-13Example 2-13
本实施例与实施例2-1的区别在于，碳源一为200g，碳源三为400g。The difference between this embodiment and Embodiment 2-1 is that carbon source one is 200g and carbon source three is 400g.
实施例2-14Example 2-14
本实施例与实施例2-11的区别在于，将D50为4μm、球形度为0.8的晶态微米硅替换为实施例1-1制备得到的D50为4μm、球形度为0.8、内部为晶态硅、表面为非晶态硅的球形微米硅。The difference between this embodiment and Example 2-11 is that the crystalline micron silicon with a D50 of 4 μm and a sphericity of 0.8 is replaced with the D50 of 4 μm, a sphericity of 0.8 and a crystalline interior prepared in Example 1-1. Silicon, spherical micron silicon with amorphous silicon surface.
对比例1Comparative example 1
(1)取1kg D50为4μm、球形度为0.8的晶态微米硅与250g沥青混合均匀，置于机械融合机中进行包覆，在氮气气氛下烧结800℃保持4h，得到该对比例的核壳结构微米硅碳复合材料。(1) Take 1kg of crystalline micron silicon with a D50 of 4 μm and a sphericity of 0.8 and mix it evenly with 250g of asphalt, place it in a mechanical fusion machine for coating, and sinter it at 800°C for 4 hours in a nitrogen atmosphere to obtain the core of this comparative example. Shell structure micron silicon carbon composite materials.
得到的核壳结构微米硅碳复合材料中，碳层的厚度为55nm。In the obtained core-shell structure micron silicon-carbon composite material, the thickness of the carbon layer is 55nm.
表3table 3
Figure PCTCN2022135031-appb-000004
Figure PCTCN2022135031-appb-000004
表4Table 4
Figure PCTCN2022135031-appb-000005
Figure PCTCN2022135031-appb-000005
Figure PCTCN2022135031-appb-000006
Figure PCTCN2022135031-appb-000006
试验例1锂电池制备及性能测试Test Example 1 Lithium Battery Preparation and Performance Test
将实施例2-1～2-13中所得的核壳结构复合材料(90wt％)与导电剂(1wt％CNT与3wt％SP)、粘结剂(4wt％CMC与2wt％SBR)和去离子水混成浆料进行涂布烘干裁切，得到锂电极片，其中“wt％”表示各组分占核壳结构复合材料、导电剂和粘结剂总重量的百分比。对锂电极片和常规电解液装配成扣式半电池，进行充放电测试。测试条件为：在5mV-0.8V电压范围，以0.1C/0.1C活化2圈，0.3C/0.3C进行循环。经测试，以实施例2-1～2-13的材料制作的电池的电化学性能参数如下表5所示。The core-shell structure composite material (90wt%) obtained in Examples 2-1 to 2-13 was mixed with conductive agent (1wt% CNT and 3wt% SP), binder (4wt% CMC and 2wt% SBR) and deionized Mix water into a slurry, apply it, dry it and cut it to obtain a lithium electrode sheet, where "wt%" represents the percentage of each component in the total weight of the core-shell structure composite material, conductive agent and binder. Assemble the lithium electrode sheet and conventional electrolyte into a button half cell, and perform charge and discharge tests. The test conditions are: in the voltage range of 5mV-0.8V, activate at 0.1C/0.1C for 2 turns, and cycle at 0.3C/0.3C. After testing, the electrochemical performance parameters of the batteries made with the materials of Examples 2-1 to 2-13 are as shown in Table 5 below.
表5table 5
编号serial number 首次可逆容量first reversible capacity 首次库伦效率first coulomb efficiency 50圈循环保持率50 lap cycle retention rate
实施例2-1Example 2-1 28162816 89.289.2 8484
实施例2-2Example 2-2 28242824 89.189.1 6262
实施例2-3Example 2-3 28692869 89.889.8 5656
实施例2-4Example 2-4 28212821 89.289.2 8383
实施例2-5Example 2-5 27852785 88.988.9 8888
实施例2-6Example 2-6 28022802 88.588.5 7878
实施例2-7Example 2-7 26782678 87.287.2 6969
实施例2-8Example 2-8 28432843 89.689.6 7979
实施例2-9Example 2-9 28212821 89.489.4 5656
实施例2-10Example 2-10 28422842 89.889.8 7676
实施例2-11Example 2-11 28632863 90.190.1 8888
实施例2-12Example 2-12 27632763 88.688.6 7272
实施例2-13Example 2-13 19571957 83.683.6 9090
实施例2-14Example 2-14 28512851 90.390.3 9292
对比例1Comparative example 1 27622762 90.890.8 2828
以上所述，仅是本申请的较佳实施例而已，并非是对本申请作其它形式的限制，任何熟悉本专业的技术人员可能利用上述揭示的技术内容加以变更或改型为等同变化的等效实施例。但是凡是未脱离本申请技术方案内容，依据本申请的技术实质对以上实施例所作的任何简单修改、等同变化与改型，仍属于本申请技术方案的保护范围。The above are only preferred embodiments of the present application, and are not intended to limit the present application in other forms. Any skilled person familiar with the art may make changes or modifications to equivalent changes using the technical contents disclosed above. Example. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still fall within the protection scope of the technical solution of the present application.

Claims (18)

  1. 一种核壳结构微米硅碳复合材料，其特征在于，其包括：A core-shell structure micron silicon carbon composite material, which is characterized in that it includes:
    由微米硅形成的内核；和A core formed from micron silicon; and
    包覆在所述内核上的碳壳层，其中所述碳壳层由内向外依次包括致密碳层一、多孔碳层和致密碳层二。A carbon shell layer covering the core, wherein the carbon shell layer includes a dense carbon layer one, a porous carbon layer and a dense carbon layer two from the inside to the outside.
  2. 根据权利要求1所述的核壳结构微米硅碳复合材料，其特征在于，所述微米硅的平均粒径D50为1～8μm，球形度为0.3～0.95。The core-shell structure micron silicon carbon composite material according to claim 1, characterized in that the average particle size D50 of the micron silicon is 1 to 8 μm, and the sphericity is 0.3 to 0.95.
  3. 根据权利要求1或2所述的核壳结构微米硅碳复合材料，其特征在于，所述致密碳层一的厚度为所述微米硅平均粒径D50的0.05％～1％，优选为0.1％～0.4％；The core-shell structure micron silicon carbon composite material according to claim 1 or 2, characterized in that the thickness of the dense carbon layer I is 0.05% to 1% of the average particle size D50 of the micron silicon, preferably 0.1% ~0.4%;
    优选地，所述致密碳层一的孔隙率为10％～50％，优选为10％～30％。Preferably, the porosity of the dense carbon layer 1 is 10% to 50%, preferably 10% to 30%.
  4. 根据权利要求1～3中任一项所述的核壳结构微米硅碳复合材料，其特征在于，所述多孔碳层的厚度为所述微米硅平均粒径D50的5％～25％，优选为10％～20％；The core-shell structure micron silicon carbon composite material according to any one of claims 1 to 3, characterized in that the thickness of the porous carbon layer is 5% to 25% of the average particle diameter D50 of the micron silicon, preferably is 10%~20%;
    优选地，所述多孔碳层的多孔由造孔剂和刻蚀剂形成，所述造孔剂选自纳米氧化锌、纳米氧化镁、纳米氧化铝、纳米氧化硅、纳米氧化铜、纳米氧化铁和纳米氧化锰中的一种或两种以上；Preferably, the pores of the porous carbon layer are formed by a pore-forming agent and an etchant, and the pore-forming agent is selected from the group consisting of nano zinc oxide, nano magnesium oxide, nano aluminum oxide, nano silicon oxide, nano copper oxide, and nano iron oxide. and one or more types of nanomanganese oxide;
    优选地，所述造孔剂的平均粒径D50为50～500nm，优选为50～200nm；Preferably, the average particle size D50 of the pore-forming agent is 50 to 500 nm, preferably 50 to 200 nm;
    优选地，所述多孔的平均孔径不小于所述造孔剂的平均粒径D50；Preferably, the average pore diameter of the pores is not less than the average particle diameter D50 of the pore-forming agent;
    优选地，所述刻蚀剂选自盐酸、硝酸和氢氟酸中的一种或两种或三种。Preferably, the etchant is selected from one, two or three types of hydrochloric acid, nitric acid and hydrofluoric acid.
  5. 根据权利要求1～4中任一项所述的核壳结构微米硅碳复合材料，其特征在于，所述致密碳层二的厚度为所述微米硅平均粒径D50的0.05％～1％，优选为0.1％～0.2％；The core-shell structure micron silicon carbon composite material according to any one of claims 1 to 4, characterized in that the thickness of the second dense carbon layer is 0.05% to 1% of the average particle diameter D50 of the micron silicon, Preferably, it is 0.1% to 0.2%;
    优选地，所述致密碳层二的孔隙率为5％～30％，优选为5％～25％。Preferably, the porosity of the second dense carbon layer is 5% to 30%, preferably 5% to 25%.
  6. 根据权利要求1～5中任一项所述的核壳结构微米硅碳复合材料，其特征在于，所述碳壳层的肖氏硬度为10～50HSD，优选为25～40HSD。The core-shell structure micron silicon-carbon composite material according to any one of claims 1 to 5, characterized in that the Shore hardness of the carbon shell layer is 10-50HSD, preferably 25-40HSD.
  7. 根据权利要求1～6中任一项所述的核壳结构微米硅碳复合材料，其特征在于，所述致密碳层一的碳源选自沥青、酚醛树脂、腐殖酸、单宁酸、聚合多巴胺、聚吡咯、甲烷和乙烷中的一种或两种以上；或者，The core-shell structure micron silicon carbon composite material according to any one of claims 1 to 6, characterized in that the carbon source of the dense carbon layer one is selected from the group consisting of asphalt, phenolic resin, humic acid, tannic acid, One or more of polymerized dopamine, polypyrrole, methane and ethane; or,
    所述多孔碳层的碳源选自沥青、酚醛树脂、腐殖酸、单宁酸、聚合多巴胺、聚吡咯、甲烷和乙烷中的一种或两种以上；或者，The carbon source of the porous carbon layer is selected from one or more of asphalt, phenolic resin, humic acid, tannic acid, polymerized dopamine, polypyrrole, methane and ethane; or,
    所述致密碳层二的碳源选自沥青、酚醛树脂、腐殖酸、单宁酸、聚合多巴胺、聚吡咯、甲烷和乙烷中的一种或两种以上。The carbon source of the dense carbon layer 2 is selected from one or more of asphalt, phenolic resin, humic acid, tannic acid, polymerized dopamine, polypyrrole, methane and ethane.
  8. 根据权利要求1～7中任一项所述的核壳结构微米硅碳复合材料，其特征在于，所述核壳结构微米硅碳复合材料的真密度为1.2～2.1g/cc，优选1.4～1.8g/cc。The core-shell structure micron silicon carbon composite material according to any one of claims 1 to 7, characterized in that the core-shell structure micron silicon carbon composite material has a true density of 1.2 to 2.1 g/cc, preferably 1.4 to 1.4 g/cc. 1.8g/cc.
  9. 一种核壳结构微米硅碳复合材料的制备方法，其特征在于，其包括下述步骤：A method for preparing core-shell structure micron silicon-carbon composite materials, which is characterized in that it includes the following steps:
    使用碳源一对微米硅进行包覆，得到包括微米硅和致密碳层一的复合颗粒一；Use a carbon source to coat a pair of micron silicon to obtain a composite particle 1 including micron silicon and a dense carbon layer 1;
    使用碳源二和造孔剂对所述复合颗粒一进行包覆，得到复合颗粒二；Use carbon source two and a pore-forming agent to coat the composite particle one to obtain composite particle two;
    将所述复合颗粒二在惰性气氛下烧结，分散于刻蚀剂中，得到包括微米硅、致密碳层一和多孔碳层的复合颗粒三；The composite particle two is sintered in an inert atmosphere and dispersed in an etchant to obtain a composite particle three including micron silicon, a dense carbon layer one and a porous carbon layer;
    使用碳源三对所述复合颗粒三进行包覆，烧结，得到包括微米硅、致密碳层一、多孔碳层和致密碳层二的核壳结构微米硅碳复合材料。The composite particle three is coated with carbon source three and sintered to obtain a core-shell structure micron silicon-carbon composite material including micron silicon, dense carbon layer one, porous carbon layer and dense carbon layer two.
  10. 根据权利要求9所述的核壳结构微米硅碳复合材料的制备方法，其特征在于，使用碳源二和造孔剂对所述复合颗粒一进行包覆，烧结，得到复合颗粒二。The method for preparing a core-shell structure micron silicon-carbon composite material according to claim 9, characterized in that the first composite particle is coated and sintered using a second carbon source and a pore-forming agent to obtain a second composite particle.
  11. 根据权利要求9或10所述的制备方法，其特征在于，使用碳源三对所述复合颗粒三进行包覆后再烧结的烧结温度为600～1100℃，优选为700～1000℃，优选使用碳源三对所述复合颗粒三进行包覆后再烧结的烧结时间为2～6h。The preparation method according to claim 9 or 10, characterized in that the sintering temperature for coating the composite particles three with carbon source three and then sintering is 600 to 1100°C, preferably 700 to 1000°C, preferably using The sintering time after the carbon source three coats the composite particle three and then sinters is 2 to 6 hours.
  12. 根据权利要求10所述的制备方法，其特征在于，使用碳源二和造孔剂对所述复合颗粒一进行包覆后再烧结的烧结温度为700～1000℃，优选为800～900℃，优选使用碳源二和造孔剂对所述复合颗粒一进行包覆后再烧结的烧结时间为1～3h。The preparation method according to claim 10, characterized in that the sintering temperature after coating the composite particles one with a carbon source two and a pore-forming agent is 700 to 1000°C, preferably 800 to 900°C, Preferably, the sintering time for coating the composite particles one with the carbon source two and the pore-forming agent and then sintering is 1 to 3 hours.
  13. 根据权利要求9～12中任一项所述的制备方法，其特征在于，所述包覆为固相包覆。The preparation method according to any one of claims 9 to 12, characterized in that the coating is solid phase coating.
  14. 一种由权利要求9～13中任一项所述的制备方法制得的核壳结构微米硅碳复合材料。A core-shell structure micron silicon-carbon composite material prepared by the preparation method according to any one of claims 9 to 13.
  15. 根据权利要求1～8中任一项所述的核壳结构微米硅碳复合材料，或根据权利要求9～13中任一项所述的制备方法，其特征在于，所述微米硅为晶态微米硅，其平均粒径D50为1～8μm，球形度为0.3～0.8。The core-shell structure micron silicon carbon composite material according to any one of claims 1 to 8, or the preparation method according to any one of claims 9 to 13, characterized in that the micron silicon is in a crystalline state Micron silicon has an average particle size D50 of 1 to 8 μm and a sphericity of 0.3 to 0.8.
  16. 根据权利要求1～8中任一项所述的核壳结构微米硅碳复合材料，或根据权利要求9～13中任一项所述的制备方法，其特征在于，所述微米硅为球形微米硅，其内部为晶态硅，表面为非晶态硅，所述球形微米硅的平均粒径D50为1～8μm，球形度为0.7～0.95；The core-shell structure micron silicon carbon composite material according to any one of claims 1 to 8, or the preparation method according to any one of claims 9 to 13, characterized in that the micron silicon is spherical micron Silicon, the interior of which is crystalline silicon and the surface is amorphous silicon, the average particle size D50 of the spherical micron silicon is 1 to 8 μm, and the sphericity is 0.7 to 0.95;
    优选地，所述球形微米硅的平均粒径D50为2～5μm；Preferably, the average particle size D50 of the spherical micron silicon is 2 to 5 μm;
    优选地，所述球形微米硅的球形度为0.8～0.95；Preferably, the sphericity of the spherical micron silicon is 0.8 to 0.95;
    优选地，所述球形微米硅的比表面积为0.5～5m 2/g，优选为1～4m 2/g； Preferably, the specific surface area of the spherical micron silicon is 0.5 to 5 m 2 /g, preferably 1 to 4 m 2 /g;
    优选地，所述非晶态硅的厚度为1～20nm，优选为2～10nm。Preferably, the thickness of the amorphous silicon is 1 to 20 nm, preferably 2 to 10 nm.
  17. 一种电极，其特征在于，其包括电极集流体和涂覆在所述电极集流体表面的电极活性物质层，所述电极活性物质层包括权利要求1～8和14中任一项所述的核壳结构微米硅碳复合材料，或由权利要求9～13中任一项所述的制备方法制得的核壳结构微米硅碳复合材料；An electrode, characterized in that it includes an electrode current collector and an electrode active material layer coated on the surface of the electrode current collector, and the electrode active material layer includes the electrode active material layer according to any one of claims 1 to 8 and 14. Core-shell structure micron silicon-carbon composite material, or core-shell structure micron silicon-carbon composite material prepared by the preparation method according to any one of claims 9 to 13;
    优选地，所述电极为负极。Preferably, the electrode is a negative electrode.
  18. 一种电池，其特征在于，其包括正极、负极、隔膜和电解质，其中所述负极是权利要求17所述的负极。A battery, characterized in that it includes a positive electrode, a negative electrode, a separator and an electrolyte, wherein the negative electrode is the negative electrode of claim 17.
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