WO2024046410A1 - 硅碳电极材料、其制备方法、负极、电池和装置 - Google Patents

硅碳电极材料、其制备方法、负极、电池和装置 Download PDF

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WO2024046410A1
WO2024046410A1 PCT/CN2023/116055 CN2023116055W WO2024046410A1 WO 2024046410 A1 WO2024046410 A1 WO 2024046410A1 CN 2023116055 W CN2023116055 W CN 2023116055W WO 2024046410 A1 WO2024046410 A1 WO 2024046410A1
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carbon
silicon
electrode material
carbon electrode
gaseous
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French (fr)
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裴大钊
王良俊
何科峰
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比亚迪股份有限公司
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/38Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386Silicon or alloys based on silicon
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B82NANOTECHNOLOGY
    • B82YSPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00Nanotechnology for materials or surface science, e.g. nanocomposites
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B82NANOTECHNOLOGY
    • B82YSPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00Manufacture or treatment of nanostructures
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • H01M10/0525Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/054Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • HELECTRICITY
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    • H01M4/04Processes of manufacture in general
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    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/04Processes of manufacture in general
    • H01M4/0402Methods of deposition of the material
    • H01M4/0421Methods of deposition of the material involving vapour deposition
    • H01M4/0428Chemical vapour deposition
    • HELECTRICITY
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    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/13Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134Electrodes based on metals, Si or alloys
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
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    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/38Selection of substances as active materials, active masses, active liquids of elements or alloys
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/58Selection 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
    • H01M4/583Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/62Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/62Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624Electric conductive fillers
    • H01M4/625Carbon or graphite
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M2004/021Physical characteristics, e.g. porosity, surface area
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
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    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M2004/026Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027Negative electrodes
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

Definitions

  • This application relates to the field of batteries, specifically silicon-carbon electrode materials, preparation methods, negative electrodes, batteries and devices.
  • silicon As an anode material, silicon has the characteristics of high specific capacity, environmental friendliness, and abundant reserves. However, silicon will undergo volume expansion during the charge and discharge process, leading to material powdering, SEI film rupture, rapid battery specific capacity attenuation, and shortened cycle life. In addition to In addition, silicon has poor electrical conductivity and cannot meet the needs of high-rate charging and discharging of batteries. The above problems severely limit the application of silicon-based materials in secondary batteries. Therefore, it is necessary to develop a new electrode material to suppress the volume expansion of silicon and enable the battery to have good cycle performance.
  • the present application provides a silicon carbon electrode material, which not only has good conductivity but also has good structural stability, and can effectively alleviate the performance attenuation problem caused by the volume expansion of silicon particles.
  • the application of silicon-carbon electrode materials in secondary batteries can improve the cycle performance of the battery and is beneficial to the preparation of high-energy-density secondary batteries.
  • the first aspect of this application provides a silicon-carbon electrode material.
  • the silicon-carbon electrode material includes porous carbon and silicon-carbon composite nanoparticles distributed in the porous carbon pores; at least part of the silicon-carbon composite nanoparticles is silicon. Silicon-carbon bonds are formed between atoms and at least some of the carbon atoms.
  • the carbon in the silicon-carbon composite nanoparticles can effectively enhance the electrochemical activity of silicon, allowing the electrode material to have good specific capacity.
  • the silicon-carbon bonds formed between carbon atoms and silicon atoms can Inhibit the expansion effect of silicon; silicon nanoparticles are distributed in the pores of porous carbon.
  • the pore structure of porous carbon can effectively disperse silicon nanoparticles, inhibit the agglomeration of silicon nanoparticles, and alleviate the problem of material disintegration caused by the concentration of expansion stress of silicon particles. , and provide buffer space for the volume expansion of silicon particles, reduce the impact of silicon particle expansion on the overall material, inhibit the powdering of the material, and help improve the cycle performance of the battery.
  • the silicon-carbon composite nanoparticles include silicon particles, carbon and silicon carbide.
  • the average depth of the pore channels is 50 nm to 150 nm.
  • the average pore diameter of the pore channels is 10 nm to 30 nm.
  • the porous carbon has a porosity of 5% to 30%.
  • the average particle size of the silicon particles is less than or equal to 4 nm.
  • the silicon particles include amorphous silicon.
  • the carbon includes amorphous carbon.
  • the mass percentage of amorphous carbon in the silicon-carbon electrode material is 50% to 80%.
  • the silicon atoms and the carbon atoms are stacked to form a tetrahedral structure.
  • the mass ratio of the silicon atoms to the carbon atoms is (1.5-4):1.
  • the porous carbon includes one or more of artificial graphite, natural graphite and hard carbon.
  • the silicon-carbon electrode material further includes carbon coated on the surface of the porous carbon and the silicon-carbon composite nanoparticles. Cladding.
  • the carbon coating layer includes at least one of amorphous carbon and graphitized carbon.
  • the carbon coating layer is an amorphous carbon coating layer.
  • the thickness of the carbon coating layer is 10 nm to 200 nm, and the mass percentage of the carbon coating layer in the silicon carbon electrode material is 5% to 10%.
  • the mass percentage of silicon element is 20% to 50%, and the mass percentage of carbon element is 50% to 80%.
  • the D v 50 of the silicon carbon electrode material is 12 ⁇ m to 18 ⁇ m.
  • the mass ratio of silicon atoms to carbon atoms in the silicon-carbon composite nanoparticles is (1.5-4):1.
  • the ratio of the total volume of the silicon-carbon composite nanoparticles to the pore volume of the carbon channels is 1: (1.01-1.05).
  • this application provides a method for preparing silicon carbon electrode materials, including:
  • the porous carbon is subjected to vapor deposition through a gaseous silicon source and a gaseous carbon source to obtain a silicon carbon electrode material; wherein, the flow ratio of the gaseous silicon source and the gaseous carbon source is (0.5-2):1; the vapor deposition
  • the temperature is 300°C ⁇ 630°C.
  • the gaseous silicon source includes one or more of SiH 4 , Si 2 H 6 , Si 3 H 8 , SiCl 4 , SiHCl 3 , Si 2 Cl 6 , SiH 2 Cl 2 , and SiH 3 Cl;
  • the gaseous carbon source includes one or more of C 2 H 2 , CH 4 , C 2 H 6 , C 2 H 4 , CO and CO 2 ; the flow rate of the gaseous silicon source and the gaseous carbon source is 5 sccm ⁇ 60 sccm, and the ventilation time of the mixed gas is 60 min ⁇ 480 min.
  • a silicon-carbon composite material is obtained, and the silicon-carbon composite material is mixed with a solid carbon source and then sintered at 400°C-1000°C to obtain the silicon-carbon electrode material;
  • the solid carbon Sources include asphalt and high molecular weight organic matter.
  • the silicon carbon electrode material is the silicon carbon electrode material provided in the first aspect of this application.
  • the present application provides a negative electrode, including the silicon carbon electrode material as described in the first aspect or the silicon carbon electrode material prepared by the preparation method as described in the second aspect.
  • the present application provides a battery, including the negative electrode as described in the third aspect.
  • the present application provides a device including the battery as described in the fourth aspect, where the device is an electrical device or an energy storage system.
  • Figure 1 is a schematic structural diagram of porous carbon provided by an embodiment of the present application.
  • Figure 2 is a flow chart of a method for preparing a silicon carbon electrode material according to an embodiment of the present application.
  • Figure 3 is an XRD characterization chart of the silicon carbon electrode material in Example 1 of the present application.
  • Figure 4 is a comparison chart of expansion rates of batteries according to various embodiments and comparative examples of the present application.
  • Silicon is considered to be the most promising anode material for high-energy-density batteries due to its high theoretical specific capacity.
  • silicon expands significantly during the metal ion deintercalation process, and the electrode material is prone to powdering and falling off, which reduces the cycle performance of the battery. . to reduce The expansion effect of silicon improves the structural stability of the electrode material.
  • This application provides a silicon-carbon electrode material.
  • the silicon-carbon electrode material includes porous carbon and silicon-carbon composite nanoparticles distributed in the porous carbon pores.
  • the porous carbon has Porous structure, silicon-carbon composite nanoparticles are distributed in the pores.
  • the porous carbon can provide strong support to the silicon-carbon composite nanoparticles, mitigating the performance attenuation caused by silicon volume expansion, and this structure can also effectively improve the conductivity of the electrode material. , promote the transmission of electrons.
  • silicon-carbon composite nanoparticles include silicon particles formed by bonds between silicon atoms and silicon atoms, carbon formed by bonds between carbon atoms and carbon atoms, and carbon formed by bonds between silicon atoms and carbon atoms. Silicon carbide.
  • the carbon in silicon-carbon composite nanoparticles can improve the electrochemical activity of silicon, fully utilize the capacity of silicon, and improve the rate performance of electrode materials.
  • the silicon-carbon electrode material includes amorphous carbon; optionally, the mass percentage of amorphous carbon in the silicon-carbon electrode material is 50% to 80%.
  • the carbon in the silicon-carbon composite nanoparticles is amorphous carbon (such as hard carbon, etc.).
  • silicon atoms and carbon atoms in silicon-carbon composite nanoparticles stack to form a tetrahedral structure. There are four carbon atoms around the silicon atom, four silicon atoms around the carbon atom, and the carbon atoms and silicon atoms are spaced apart. , forming a conductive network inside the silicon-carbon composite nanoparticles, thereby greatly improving the conductivity of the silicon particles.
  • the mass ratio of silicon atoms to carbon atoms is (1.5 ⁇ 4):1.
  • the mass ratio of silicon atoms to carbon atoms can be, but is not limited to, 1.5:1 or 2. :1, 3:1 or 4:1. Controlling the mass ratio of silicon atoms to carbon atoms within the above range can ensure that silicon-carbon electrode materials have high specific capacity and rate performance.
  • the average depth of the porous carbon channels is 50 nm to 150 nm.
  • the depth of the porous carbon channel refers to the length of the porous carbon channel in its extension direction
  • the pore diameter of the porous carbon channel refers to the diameter of the channel on the outer surface.
  • the average depth of the porous carbon channel can be, but is not limited to, 50nm, 80nm, 100nm, 120nm, 150nm.
  • the average pore diameter of the pore channels is 10 nm to 30 nm.
  • the average pore diameter of the porous carbon channels may be, but is not limited to, 10 nm, 15 nm, 20 nm or 30 nm.
  • the porous carbon of this structure is not only conducive to fully dispersing silicon-carbon composite nanoparticles, thereby avoiding excessive concentration of silicon expansion stress and improving the structural stability of the material, but is also conducive to mitigating the problem of nano-silicon oxidation.
  • the porous carbon has a hollow structure, and the internal pores are a uniformly distributed columnar structure, that is, the cross-section of the pores is circular.
  • the porous carbon includes one or more of artificial graphite, natural graphite or hard carbon.
  • the silicon-carbon composite nanoparticles can interact with the porous carbon through covalent bonds to form a structurally stable silicon-carbon electrode material. .
  • the average particle size of the silicon particles in the silicon-carbon composite nanoparticles is less than or equal to 4 nm. In some embodiments, the average particle size of the silicon particles is less than or equal to 4 nm and greater than or equal to 0.5 nm.
  • the average particle size of the silicon particles may be, but is not limited to, 0.5 nm, 1 nm, 2 nm, 3 nm or 4 nm. Smaller silicon particles not only facilitate the rapid extraction or insertion of lithium ions, thereby improving the rate performance of the material, but also have a weak volume expansion and powdering effect, which is beneficial to improving the structural stability of the electrode material.
  • the silicon particles include amorphous silicon; in some embodiments of the present application, the silicon particles are amorphous silicon. Compared with crystalline silicon, amorphous silicon has a low expansion rate and stable structure after being embedded with lithium.
  • the ratio of the total volume of the silicon-carbon composite nanoparticles in the porous carbon channels to the pore volume of the carbon channels is 1: (1.01 ⁇ 1.05), where the unit of the total volume of the silicon-carbon composite nanoparticles is nm 2 , the pore volume unit of carbon channels is nm 2 .
  • Controlling the ratio of the size of silicon-carbon composite nanoparticles to the pore volume of carbon channels is beneficial to providing buffer space for the volume expansion of silicon particles, reducing the impact of silicon particle expansion on the overall material, inhibiting the powdering of the material, and ensuring that the overall material has a high capacity.
  • the silicon-carbon electrode material also includes a carbon coating layer coating the surface of porous carbon and silicon-carbon composite nanoparticles; in some embodiments of the present application, the carbon coating layer includes amorphous carbon and graphitized carbon. one or more of them. carbon The coating layer can further improve the structural stability and conductivity of silicon-carbon electrode materials.
  • the carbon coating layer is an amorphous carbon coating layer, and the amorphous carbon structure is stable and has good rate performance.
  • the thickness of the carbon coating layer is 10 nm to 200 nm, and the mass percentage of the carbon coating layer in the silicon carbon electrode material is 5% to 10%.
  • the mass percentage of silicon element in the silicon-carbon electrode material, is 20% to 50%, and the mass percentage of carbon element is 50% to 80%.
  • the content of carbon element can be determined by thermogravimetry. As measured by the analyzer, the content of silicon element can be measured by the following method: after dissolving the silicon carbon electrode material with hydrofluoric acid, ICP elemental analysis is used to measure the content of silicon element in the electrode material.
  • the mass percentage of silicon element in the silicon-carbon electrode material may be, but is not limited to, 20%, 30%, 33%, 35%, 37%, 40%, 45% or 50%. In some embodiments, the mass percentage of amorphous carbon in the silicon-carbon electrode material is 10% to 20%.
  • Controlling the carbon content can ensure that the silicon-carbon electrode material has good ionic conductivity, which is beneficial to improving the conductivity of the silicon-carbon electrode material to ions, reducing material polarization, promoting the migration of ions, and giving the battery good rate performance.
  • the D v 50 of the silicon carbon electrode material is 12 ⁇ m to 18 ⁇ m.
  • the D v 50 of the silicon carbon electrode material may be, but is not limited to, 12 ⁇ m, 14 ⁇ m, 15 ⁇ m, 16 ⁇ m or 18 ⁇ m.
  • the pore structure of the porous carbon can disperse small-sized silicon-carbon composite nanoparticles and provide buffer space for the volume change of silicon during the charge and discharge process, thereby improving the structural stability of the material.
  • the carbon atoms in carbon composite nanoparticles can effectively improve the electrochemical activity of electrode materials, allowing silicon materials to have good rate performance and specific capacity. Its application in secondary batteries can improve the rate performance and cycle performance of the secondary battery, which is beneficial to the long-term use of the battery.
  • this application also provides a preparation method for the above-mentioned silicon carbon electrode material, including:
  • 201 Perform vapor deposition of porous carbon through gaseous silicon source and gaseous carbon source to obtain silicon carbon electrode material.
  • the flow ratio of the gaseous silicon source and the gaseous carbon source is (0.5 ⁇ 2):1, and the temperature of vapor deposition is 300°C ⁇ 630°C.
  • Figure 1 is a schematic structural diagram of porous carbon provided by an embodiment of the present application.
  • the surface of the porous carbon has a porous structure.
  • the D v 50 of the porous carbon is 12 ⁇ m to 18 ⁇ m
  • the average depth of the channels in the porous carbon is 50 nm to 150 nm
  • the average pore diameter of the channels is 10 nm to 30 nm
  • the porosity of the porous carbon is 5% to 30%. Controlling the size structure of porous carbon is beneficial to the uniform deposition of silicon-carbon composite nanoparticles in the pores of porous carbon, thereby promoting the formation of small-sized silicon-carbon composite nanoparticles.
  • the porous carbon includes one or more of artificial graphite, natural graphite or hard carbon.
  • the preparation method of porous carbon includes: providing a carbon material, which includes one or more of artificial graphite, natural graphite or hard carbon; placing the carbon material in a heat treatment equipment, and passing the carbon material into the heat treatment equipment.
  • Carbon dioxide is used to etch carbon materials.
  • the etching temperature is 200°C to 800°C, and the flow rate of carbon dioxide gas is 10 sccm to 50 sccm.
  • the heat treatment equipment can be a rotary furnace, and the rotation speed of the rotary furnace is 3°/min to 12 °/min.
  • the gaseous silicon source is cracked to form silicon atoms, and the gaseous carbon source is cracked to form carbon atoms. Since the bonding energy of the Si-C bond is lower than that of the Si-Si bond Bond energy, so the carbon atoms generated by the cracking of the gaseous carbon source can pre-form Si-C bonds with silicon atoms, inhibiting the formation of Si-Si bonds and preventing the growth of deposited silicon after nucleation, thus forming small-sized silicon-carbon composite nanoparticles. .
  • the flow ratio of the gaseous silicon source and the gaseous carbon source is (0.5 ⁇ 2):1.
  • the flow ratio of the gaseous silicon source and the gaseous carbon source can be, but is not limited to, 0.5:1, 0.8:1, or 1. :1, 1.5:1 or 2:1. Controlling the flow ratio of the gaseous silicon source and the gaseous carbon source can ensure the orderly deposition of carbon atoms and silicon atoms to form silicon-carbon composite nanoparticles, thereby promoting the capacity of the silicon particles.
  • the flow rate of the gaseous silicon source is 5 sccm to 60 sccm.
  • the flow rate of the gaseous silicon source can be, but is not limited to, 5 sccm, 10 sccm, 20 sccm, 30 sccm, 40 sccm or 60 sccm.
  • the flow rate of the gaseous carbon source is 5 sccm to 60 sccm.
  • the flow rate of the gaseous carbon source can be, but is not limited to, 5 sccm, 10 sccm, 20sccm, 30sccm, 40sccm or 60sccm.
  • the ventilation time of the mixed gas is 60 minutes to 480 minutes. Controlling the flow of gas can promote the uniform deposition of silicon nanoparticles in the pores of porous carbon.
  • the temperature of vapor deposition is 300°C to 630°C.
  • the temperature of vapor deposition can be, but is not limited to, 300°C, 400°C, 450°C, 500°C, 600°C or 630°C. Vapor deposition at this temperature can form silicon with an amorphous structure, and carbon atoms can effectively combine with silicon to form silicon-carbon composite nanoparticles.
  • the temperature of vapor deposition is 300°C to 500°C. Considering that the carbon source cracking reaction rate decreases at low temperatures and affects the carbon source utilization, a small amount of catalyst is added to the porous carbon.
  • the catalyst includes copper oxide, Nickel oxide or platinum metal catalyst promotes the cracking of the carbon source.
  • the gaseous silicon source includes one or more of SiH 4 , Si 2 H 6 , Si 3 H 8 , SiCl 4 , SiHCl 3 , Si 2 Cl 6 , SiH 2 Cl 2 , and SiH 3 Cl ;
  • the gaseous carbon source includes one or more of C 2 H 2 , CH 4 , C 2 H 6 , C 2 H 4 , CO and CO 2 .
  • the gaseous silicon source is SiH 4 and the gaseous carbon source is C 2 H 4 .
  • the gas cracking efficiency is high and can be evenly filled in the pores of porous carbon to form a dense structural material; on the other hand, the hydrogen generated by cracking can be recycled and saved. energy.
  • the silicon-carbon electrode material further includes a carbon coating layer coating the surface of the porous carbon and the silicon-carbon composite nanoparticles.
  • the porous carbon can be subjected to a vapor deposition process to obtain silicon.
  • a silicon-carbon composite material in which carbon composite nanoparticles are distributed in porous carbon channels is further carbon-coated.
  • the carbon coating method includes: combining the silicon-carbon composite material with a solid carbon source.
  • the stirring speed is 300r/min ⁇ 800r/min
  • the stirring time is 30min ⁇ 180min
  • the solid carbon source includes one or more of asphalt and polymer organic matter
  • the asphalt includes petroleum asphalt
  • high molecular organic matter includes one or more of alcohol, resin and sugar
  • alcohol includes one or more of polyfurfuryl alcohol or polyvinyl alcohol
  • resin includes cyclic One or more of oxygen resin, phenolic resin and melamine resin
  • the sugar includes one or more of glucose and sucrose.
  • a second carbon coating layer is further prepared on the surface of the carbon coating layer.
  • the preparation method of the second carbon coating layer includes: placing the silicon-carbon composite material with the carbon coating layer in a heat treatment device to perform vapor phase carbon deposition.
  • the carbon source of the vapor phase carbon deposition includes methane, ethylene, acetylene, propane or propylene.
  • the temperature of vapor phase carbon deposition is 300-900°C.
  • vapor deposition is performed at 300-600°C to form an amorphous carbon coating layer, and the amorphous carbon coating layer has good rate performance.
  • the preparation method of silicon carbon electrode material includes: placing porous carbon in a vacuum stainless steel tubular furnace.
  • the vacuum stainless steel tubular furnace has two vents, which can carry out ventilation reactions at the same time.
  • the gaseous silicon source and the gaseous carbon source are introduced into the tube furnace.
  • the flow ratio of the gaseous silicon source and the gaseous carbon source is (0.5 ⁇ 2):1.
  • the gaseous silicon source and the gaseous carbon source undergo thermal decomposition and coexist in the vacuum tube furnace.
  • the deposition generates silicon-carbon composite nanoparticles, and the silicon-carbon composite nanoparticles are deposited in the pores of the porous carbon to form a silicon-carbon composite material; the silicon-carbon composite material and the solid carbon source are evenly mixed in a stirring tank and then placed in a vacuum tube furnace Medium vacuum sintering forms a carbon coating layer and obtains silicon carbon electrode material.
  • the preparation method of silicon carbon electrode material provided by this application can obtain electrode materials with new structures.
  • the method has a simple process and is conducive to large-scale production.
  • the present application also provides a negative electrode, which includes the silicon carbon electrode material of the present application.
  • the negative electrode includes a current collector and a negative electrode material layer disposed on the current collector, wherein the negative electrode material layer includes the silicon carbon electrode material of the present application.
  • the negative electrode material layer can be prepared by mixing silicon carbon electrode material, conductive agent, binder and solvent to form negative electrode slurry, The negative electrode slurry is then coated and dried to obtain the negative electrode material layer.
  • the binder may be selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polyimide ( One or more of PI), polyacrylic acid (PAA), polyacrylate, polyolefin, sodium carboxymethylcellulose (CMC) and sodium alginate.
  • the conductive agent may be selected from one or more types of carbon nanotubes, carbon black, and graphene.
  • the battery includes a positive electrode, a negative electrode, an electrolyte, and a separator located between the positive electrode and the negative electrode, wherein the negative electrode includes the negative electrode provided by the present application.
  • the battery includes a positive electrode, a negative electrode, and a solid electrolyte or semi-solid electrolyte located between the positive electrode and the negative electrode.
  • the battery is a secondary battery, and the secondary battery can be any one of a lithium-ion battery, a sodium-ion battery, a potassium-ion battery, an aluminum-ion battery, a zinc-ion battery, or a magnesium-ion battery.
  • the positive electrode of the secondary battery may be any positive electrode known in the art.
  • the active material of the positive electrode is a material capable of reversibly extracting and inserting lithium ions; in some embodiments, the active material of the positive electrode is a material capable of reversibly extracting and inserting sodium ions; in some embodiments, the active material of the positive electrode is a material capable of reversibly extracting and inserting sodium ions.
  • the active material is a material capable of reversibly extracting and inserting potassium ions; in some embodiments, the active material of the positive electrode is a material capable of reversibly extracting and inserting magnesium ions.
  • the separator of the secondary battery can be any separator known to those skilled in the art.
  • the separator can be a polyolefin microporous membrane, polyethylene terephthalate, polyethylene felt, glass fiber mat or ultrafine One or more types of fiberglass paper.
  • the electrolyte of the secondary battery includes a solution of electrolyte lithium salt in a non-aqueous solvent.
  • the electrolyte lithium salt includes lithium hexafluorophosphate (LiPF 6 ), lithium perchlorate (LiClO 4 ), lithium tetrafluoroborate (LiBF 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium hexafluorosilicate ( Li 2 SiF 6 ), lithium tetraphenylborate (LiB(C 6 H5) 4 ), lithium chloride (LiCl), lithium bromide (LiBr), lithium chloroaluminate (LiAlCl 4 ), lithium fluoroalkyl sulfonate (LiC( One or more of SO 2 CF 3 ) 3 ), LiCH 3 SO 3 , LiN(SO 2 CF 3 ) 2 and LiN(SO 2 C 2 F 5 )
  • the non-aqueous solvent includes one or more of chain acid esters and cyclic acid esters.
  • chain acid esters include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC) and dipropyl carbonate (DPC). ) one or more.
  • chain acid esters include chain organic esters containing fluorine, sulfur, or unsaturated bonds.
  • the cyclic acid ester includes ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), ⁇ -butyrolactone ( ⁇ -BL) and sultone. one or more.
  • the cyclic acid ester includes fluorine-containing, sulfur-containing or unsaturated bond-containing cyclic organic ester.
  • the non-aqueous solvent includes one or more of chain ether and cyclic ether solutions.
  • the cyclic ethers include tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), 1,3-dioxopentane (DOL) and 4-methyl-1,3-dioxo One or more of cyclopentane (4-MeDOL).
  • the cyclic ether includes fluorine-containing, sulfur-containing or unsaturated bond-containing cyclic organic ether.
  • chain ethers include dimethoxymethane (DMM), 1,2-dimethoxyethane (DME), 1,2-dimethoxypropane (DMP) and diethylene glycol One or more of dimethyl ether (DG).
  • chain ethers include fluorine-containing, sulfur-containing or unsaturated bond-containing chain organic ethers.
  • concentration of the electrolyte lithium salt in the electrolyte is 0.1 mol/L-15 mol/L. In some embodiments of the present application, the concentration of the electrolyte lithium salt is 1 mol/L-10 mol/L.
  • the battery may be prepared using either a lamination process or a winding process.
  • the device can be, for example, an electrical device or an energy storage system.
  • the battery supplies power to the electrical device or energy storage system;
  • the electrical device can be a vehicle or an electronic device. etc.
  • the means of transportation can be, for example, vehicles, ships, etc., and the electronic equipment can be, for example, 3C products (computer, communication and consumer electronics). products) etc.
  • a preparation method of silicon carbon electrode material including:
  • the tube furnace is heated to 475°C.
  • Monosilane and ethylene are introduced into the tube furnace.
  • the flow rate of monosilane gas is 10 sccm and the flow rate of ethylene gas is 20 sccm.
  • the ventilation gas flow ratio of silane and ethylene is 0.5:1, and the ventilation time is 240 minutes to obtain the silicon carbon composite material; take 100g silicon carbon composite material and 10g asphalt and stir it in a mixing tank to obtain a mixture.
  • the stirring speed is 550r/min and the time is 60 minutes; the mixture was placed in a vacuum tube furnace for vacuum sintering at 600°C for 6 hours to obtain silicon carbon electrode material.
  • Preparation of negative electrode sheet Mix silicon carbon electrode material, sodium carboxymethyl cellulose, and acetylene black at a mass ratio of 8:1:1 to obtain negative electrode slurry. Use a scraper to apply the negative electrode slurry on the copper foil. After drying, rolling and cutting, the negative electrode piece is obtained.
  • a lithium sheet was used as the counter electrode sheet and a polyethylene/polypropylene (PE/PP) composite separator was used as the separator.
  • PE/PP polyethylene/polypropylene
  • a button battery was made using conventional methods in this field.
  • the battery of Example 1 was named S1.
  • Porous carbon was prepared using the same method as in Example 1. Place 30 g of porous carbon in a vacuum stainless steel tubular furnace. The tubular furnace was heated to 475°C, and monosilane, ethylene, and monosilane gas were introduced into the tubular furnace. The circulation volume is 20sccm, the ethylene gas circulation volume is 20sccm, the ventilation gas flow ratio of monosilane and ethylene is 1:1, and the ventilation time is 120min to obtain the silicon-carbon composite material; take 100g silicon-carbon composite material and 10g asphalt and stir it in a mixing tank The mixture was obtained with a stirring speed of 550 r/min and a stirring time of 60 minutes. The mixture was placed in a vacuum tube furnace and vacuum sintered at 600°C for 6 hours to obtain silicon carbon electrode material.
  • the negative electrode sheet and battery were prepared using the same method as Example 1, and the battery of Example 2 was named S2.
  • Porous carbon was prepared using the same method as in Example 1. Place 30 g of porous carbon in a vacuum stainless steel tubular furnace. The tubular furnace was heated to 475°C, and monosilane, ethylene, and monosilane gas were introduced into the tubular furnace. The circulation volume is 40 sccm, the ethylene gas circulation volume is 20 sccm, the ventilation gas flow ratio of monosilane and ethylene is 2:1, and the ventilation time is 60 minutes to obtain the silicon carbon composite material; take 100g silicon carbon composite material and 10g asphalt and stir it in a mixing tank The mixture was obtained with a stirring speed of 550 r/min and a stirring time of 60 minutes. The mixture was placed in a vacuum tube furnace and vacuum sintered at 600°C for 6 hours to obtain silicon carbon electrode material.
  • the negative electrode sheet and battery were prepared using the same method as Example 1, and the battery of Example 3 was named S3.
  • the silicon carbon composite material was prepared using the same method as in Example 1; 100 g of the silicon carbon composite material and 10 g of asphalt were stirred in a mixing tank to obtain a mixture. The stirring speed was 550 r/min and the time was 60 minutes; the mixture was placed in a vacuum tube Vacuum sintering is performed in the furnace at 600°C for 6 hours to obtain a silicon-carbon composite material coated with an amorphous carbon layer. Place the silicon-carbon composite material coated with an amorphous carbon layer into a vacuum rotary furnace and pass it into the vacuum rotary furnace. Methane gas is used for gas phase coating. The rotation speed of the rotary furnace is 6°/min, the temperature is 800°C, and the methane gas flow rate is 20 sccm to obtain silicon carbon electrode material.
  • the negative electrode sheet and battery were prepared using the same method as Example 1, and the battery of Example 4 was named S4.
  • the rotation speed of the rotary furnace is 15°/min
  • the temperature is 900°C
  • the carbon dioxide gas flow rate is 60 sccm
  • the reaction time is 300min.
  • the silicon carbon electrode material, negative electrode sheet and battery were prepared using the same method as Example 1.
  • the battery of Example 5 was named S5.
  • Example 6 uses the same method as Example 1 to prepare porous carbon and perform vapor deposition on the porous carbon. After passing in the gaseous silicon source and the gaseous carbon source, silicon-carbon composite nanoparticles are deposited in the pores of the porous carbon to obtain a silicon-carbon composite. material, that is, silicon carbon electrode material is obtained.
  • the negative electrode sheet and battery were prepared using the same method as Example 1, and the battery of Example 6 was named S6.
  • Porous carbon was prepared using the same method as in Example 1. Place 30 g of porous carbon in a vacuum stainless steel tubular furnace. The tubular furnace was heated to 475°C, and monosilane, ethylene, and monosilane gas were introduced into the tubular furnace. The circulation volume is 80 sccm, the ethylene gas circulation volume is 80 sccm, the ventilation gas flow ratio of monosilane and ethylene is 1:1, the ventilation time is 60 minutes, and the silicon carbon composite material is obtained; take 100g silicon carbon composite material and 10g asphalt and stir it in a mixing tank The mixture was obtained with a stirring speed of 550 r/min and a stirring time of 60 minutes. The mixture was placed in a vacuum tube furnace and vacuum sintered at 600°C for 6 hours to obtain silicon carbon electrode material.
  • the negative electrode sheet and battery were prepared using the same method as Example 1, and the battery of Example 7 was named S7.
  • the tube furnace is heated to 475°C.
  • Monosilane and ethylene are introduced into the tube furnace.
  • the flow rate of monosilane gas is 10 sccm and the flow rate of ethylene gas is 20 sccm.
  • the ventilation gas flow ratio of silane and ethylene is 0.5:1, and the ventilation time is 240 minutes to obtain the silicon carbon composite material; take 100g silicon carbon composite material and 10g asphalt and stir it in a mixing tank to obtain a mixture.
  • the stirring speed is 550r/min and the time is 60 minutes; the mixture was placed in a vacuum tube furnace for vacuum sintering at 600°C for 6 hours to obtain silicon carbon electrode material.
  • the negative electrode sheet and battery were prepared using the same method as Example 1, and the battery of Example 8 was named S8.
  • the rotation speed of the rotary furnace is 10°/min
  • the temperature is 600°C
  • the carbon dioxide gas flow rate is 35 sccm
  • the reaction time is 300 min. .
  • the tube furnace is heated to 475°C.
  • Monosilane and ethylene are introduced into the tube furnace.
  • the flow rate of monosilane gas is 10 sccm and the flow rate of ethylene gas is 20 sccm.
  • the ventilation gas flow ratio of silane and ethylene is 0.5:1, and the ventilation time is 240 minutes to obtain the silicon carbon composite material; take 100g silicon carbon composite material and 10g asphalt and stir it in a mixing tank to obtain a mixture.
  • the stirring speed is 550r/min and the time is 60 minutes; the mixture was placed in a vacuum tube furnace for vacuum sintering at 600°C for 6 hours to obtain silicon carbon electrode material.
  • the negative electrode sheet and battery were prepared using the same method as Example 1, and the battery of Example 9 was named S9.
  • the rotation speed of the rotary furnace is 15°/min, the temperature is 600°C, the carbon dioxide gas flow rate is 10 sccm, and the reaction time is 300 min. .
  • Silane and ethylene the monosilane gas flow rate is 10 sccm
  • the ethylene gas flow rate is 20 sccm
  • the monosilane and ethylene ventilation gas flow ratio is 0.5:1
  • the ventilation time is 240 minutes
  • the silicon carbon composite material is obtained; take 100g silicon carbon composite material and Stir 10g of asphalt in a mixing tank to obtain a mixture.
  • the stirring speed is 550r/min and the time is 60 minutes.
  • the mixture is placed in a vacuum tube furnace for vacuum sintering at 600°C for 6 hours to obtain silicon carbon electrode material.
  • the negative electrode sheet and battery were prepared using the same method as Example 1, and the battery of Example 10 was named S10.
  • Comparative Example 1 uses a commercial silicon carbon product.
  • the structure of the silicon carbon product is a pomegranate-like structure.
  • the nano-silicon in this silicon-carbon product is made from micron-sized silicon particles by sanding to the nano-scale.
  • the average particle size of the nano-silicon is 100nm.
  • This silicon carbon product is obtained by dispersing nano silicon in graphite and amorphous carbon. Take 100g of silicon-carbon composite material and 10g of asphalt and stir in a mixing tank to obtain a mixture.
  • the stirring speed is 550r/min and the time is 60 minutes.
  • the mixture is placed in a vacuum tube furnace for vacuum sintering at 600°C for 6 hours to obtain the silicon-carbon product. .
  • the negative electrode sheet and battery were prepared using the same method as Example 1, and the battery of Comparative Example 1 was named D1.
  • Porous carbon was prepared using the same method as Example 1. Place 30 g of porous carbon in a vacuum stainless steel tubular furnace. The tube furnace was heated to 475°C. Monosilane, nitrogen, and monosilane gas were introduced into the tube furnace. The circulation volume is 10sccm, the nitrogen gas circulation volume is 50sccm, the ratio of monosilane and nitrogen ventilation gas flow is 1:5, the ventilation time is 240min, and the uncoated silicon carbon material is obtained; take 100g of the uncoated silicon carbon material and 10g The asphalt is stirred in a mixing tank to obtain a mixture. The stirring speed is 550r/min and the time is 60 minutes. The mixture is placed in a vacuum tube furnace for vacuum sintering at 600°C for 6 hours to obtain silicon carbon electrode material.
  • the negative electrode sheet and battery were prepared using the same method as Example 1, and the battery of Comparative Example 2 was named D2.
  • Comparative Example 3 graphite was directly vapor deposited (the graphite was not etched), and the silicon carbon electrode material, negative electrode sheet and battery were prepared using the same method as Example 1.
  • the battery in Comparative Example 3 was named D3.
  • Example 2 the flow rates of the silicon source and the carbon source are larger than in Example 1, so the particle size of the silicon nanoparticles in the obtained silicon carbon electrode material is larger.
  • the silicon-carbon electrode material in Example 4 was further coated with carbon by vapor deposition, and the particle size of the obtained silicon-carbon electrode material was relatively large; in Example 5, when the carbon material was etched, the carbon dioxide gas flow rate was large, and the obtained porous carbon The pore size of the pores is larger, and the size of the resulting silicon nanoparticles after vapor deposition is larger.
  • the silicon carbon electrode material of Example 6 does not contain a carbon coating layer, and the particle size of the silicon carbon electrode material is relatively small; the silicon carbon electrode material of Example 7 has a large gas flow during preparation, and the gas is easily agglomerated after cracking, resulting in nanometer
  • the size of the silicon particles is larger; when etching the carbon material in Example 8, the temperature in the tubular furnace is low, and the size of the porous carbon channels obtained is smaller. After vapor deposition, the size of the silicon nanoparticles obtained is close to that of the porous carbon channels. aperture.
  • Comparative Example 2 uses a mixed system of gaseous silicon source and carrier gas for vapor deposition, that is, the mixed gas does not contain gaseous carbon source, the particle size of the silicon nanoparticles obtained is larger, and the expansion effect of the electrode material is still very significant.
  • Comparative Example 3 directly deposits the carbon material, and the gas is cracked and deposited on the surface of the carbon material, resulting in the agglomeration of nano-silicon, and the expansion effect of silicon is strong.
  • thermogravimetric analyzer to characterize the carbon content in the silicon carbon electrode materials of each embodiment and the electrode materials of each comparative example. After dissolving the silicon carbon electrode materials with hydrofluoric acid, use ICP elemental analysis to measure the silicon in the electrode materials. content, and the characterization results are shown in Table 2.
  • Example 1 Example 2 and Example 3 the ventilation gas flow ratios of monosilane and ethylene are different. As the monosilane content increases, the silicon content in the silicon carbon electrode material also increases.
  • Example 4 CVD carbon coating is performed on the basis of Example 1. The carbon content of CVD carbon coating is about 4%, so the carbon content of Example 4 is increased. In Example 5, the carbon dioxide gas flow rate is larger during the etching process of carbon materials.
  • the etching effect is poor, but it basically does not affect the silicon content and carbon content; in Example 6, the silicon carbon material is not coated with carbon, so the carbon content will decrease, and the corresponding silicon content will increase; the deposition process of silicon and carbon in Example 7 The gas circulation of monosilane and ethylene increases, and the porous carbon content is fixed, so the silicon content increases; in Example 8, the average pore diameter and pore depth of the porous carbon are small, and the silicon deposition process will cause pore blocking, and the silicon deposition performance is poor. , the silicon content is reduced.
  • Comparative Example 1 is a commercial silicon-carbon material. Nano-silicon and carbon materials are composited by sanding. The content of nano-silicon can be adjusted during the composite process, and 50% silicon content is blended. Comparative Example 2 has no ethylene gas during the deposition process, so the silicon content is higher. ;Compared with Example 1, Comparative Example 3 has no post-hole formation in graphite and has less impact on the silicon content.
  • Figure 3 is an XRD characterization chart of the silicon carbon electrode material of Example 1 of the present application.
  • the silicon in silicon carbon electrode materials is amorphous silicon.
  • the LANHE blue battery testing system was used to test the electrochemical performance of the batteries of each embodiment and comparative example.
  • the specific test conditions are: discharge the battery to 0.005V at a constant current of 0.01C at room temperature, and then discharge it to 0.1C at a constant current of 0.1C. Constant current charging to 1.5V, this process is recorded as one cycle.
  • Table 3 The battery performance of each embodiment and comparative example is shown in Table 3.
  • the silicon nanoparticles in the silicon carbon electrode materials of Example 1 and Example 4 have smaller particle sizes, so the remaining capacity retention rate of the battery is higher.
  • the silicon carbon electrode material of Example 3 has a higher silicon content. Therefore, the battery has a high first reversible capacity.
  • Example 6 is not coated, resulting in poor conductivity of the material and exposed silicon particles on the surface of the silicon carbon material. The capacity and first efficiency are relatively low, and the capacity retention rate is poor.
  • silicon-carbon electrode material of Example 8 silicon blocks the pores during the deposition process, causing the silicon particles to become trapped in the carbon. The dispersion in the pore channels is uneven, and there are a large number of cavities in the porous carbon. The expansion of the silicon material and interface side reactions lead to poor capacity retention.
  • Figure 4 is a comparison chart of the expansion rates of batteries according to various embodiments and comparative examples of the present application. It can be seen from Table 4 and Figure 4 that the pole pieces prepared using the silicon carbon electrode materials of the present application have better Stability, battery expansion rate is low.
  • the content of monosilane relative to ethylene during the preparation of the silicon-carbon composite nanoparticles in Example 3 is too high, the size of the silicon particles in the formed silicon-carbon composite nanoparticles is larger, and the material expansion effect is stronger; in Example 5 During the preparation of the silicon-carbon composite nanoparticles, the pore diameter of the porous carbon is too large, and the size of the silicon particles in the silicon-carbon composite nanoparticles is larger, and the material expansion effect is stronger; in Example 7, the gas flow rate of the silicon-carbon composite nanoparticles is too high during the preparation. Large, the size of the silicon particles formed is larger, and the material expansion effect is stronger.

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Abstract

一种硅碳电极材料、该硅碳电极材料的制备方法、一种负极、一种包括该负极的电池以及一种包括该电池的装置,该硅碳电极材料包括多孔碳和分布在该多孔碳孔道中的硅碳复合纳米颗粒。该硅碳复合纳米颗粒中至少部分硅原子和至少部分碳原子之间形成硅碳键。

Description

硅碳电极材料、其制备方法、负极、电池和装置
本申请要求于2022年08月31日提交中国专利局、申请号为202211062239.2、申请名称为“硅碳电极材料及其制备方法和应用”的中国专利申请的优先权,其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电池领域,具体涉及硅碳电极材料、其制备方法、负极、电池和装置。
背景技术
硅作为负极材料具有高比容量、环境友好、储量丰富等特点,然而硅在充放电过程中会发生体积膨胀,导致材料粉化、SEI膜破裂、电池比容量快速衰减,循环寿命缩短等,除此之外,硅的导电性较差,不能满足电池大倍率充放电的需求,以上问题严重限制了硅基材料在二次电池中的应用。因此,有必要开发一种新型的电极材料,以抑制硅的体积膨胀,使电池具有良好的循环性能。
发明内容
有鉴于此,本申请提供了一种硅碳电极材料,该硅碳电极材料不仅具有良好的导电性并且具有良好的结构稳定性,可以有效地缓解硅颗粒体积膨胀引起的性能衰减问题,将该硅碳电极材料应用在二次电池可以提高电池的循环性能,有利于制备高能量密度的二次电池。
本申请第一方面提供了一种硅碳电极材料,所述硅碳电极材料包括多孔碳和分布在所述多孔碳孔道中的硅碳复合纳米颗粒;所述硅碳复合纳米颗粒中至少部分硅原子和至少部分碳原子之间形成硅碳键。
本申请的硅碳电极材料中,硅碳复合纳米颗粒中的碳可以有效地提升硅的电化学活性,使电极材料具有良好的比容量发挥,碳原子和硅原子之间形成的硅碳键可以抑制硅的膨胀效应;硅纳米颗粒分布在多孔碳的孔道中,多孔碳的孔道结构与可以有效地分散硅纳米颗粒,抑制硅纳米颗粒的团聚,缓解硅颗粒膨胀应力集中导致材料崩解的问题,并且为硅颗粒的体积膨胀提供缓冲空间,减轻硅颗粒膨胀对材料整体的影响,抑制材料的粉化,有利于改善电池的循环性能。
可选地,所述硅碳复合纳米颗粒包括硅颗粒、碳和碳化硅。
可选地,所述孔道的平均深度为50nm~150nm。
可选地,所述孔道的平均孔径为10nm~30nm。
可选地,所述多孔碳的孔隙率为5%~30%。
可选地,所述硅颗粒的平均粒径小于或等于4nm。
可选地,所述硅颗粒包括非晶硅。
可选地,所述碳包括无定形碳。
可选地,所述硅碳电极材料中无定形碳的质量百分含量为50%~80%。
可选地,所述硅碳复合纳米颗粒中,所述硅原子和所述碳原子堆积形成四面体结构。
可选地,所述硅碳复合纳米颗粒中,所述硅原子与所述碳原子的质量比为(1.5~4):1。
可选地,所述多孔碳包括人造石墨、天然石墨和硬碳中的一种或多种。
可选地,所述硅碳电极材料还包括包覆在所述多孔碳和所述硅碳复合纳米颗粒表面的碳 包覆层。
可选地,所述碳包覆层包括无定形碳和石墨化碳中的至少一种。
可选地,所述碳包覆层为无定形碳包覆层。
可选地,所述碳包覆层的厚度为10nm~200nm,所述碳包覆层在所述硅碳电极材料中的质量百分含量为5%~10%。
可选地,所述硅碳电极材料中,硅元素的质量百分含量为20%~50%,碳元素的质量百分含量为50%~80%。
可选地,所述硅碳电极材料的Dv50为12μm~18μm。
可选地,所述硅碳复合纳米颗粒中的硅原子与碳原子的质量比为(1.5~4):1。
可选地,所述硅碳复合纳米颗粒的总体积与所述碳孔道的孔容之比为1:(1.01~1.05)。
第二方面,本申请提供了一种硅碳电极材料的制备方法,包括:
对多孔碳通气态硅源和气态碳源进行气相沉积,得到硅碳电极材料;其中,所述气态硅源和所述气态碳源的流量比为(0.5~2):1;所述气相沉积的温度为300℃~630℃。
可选地,所述气态硅源包括SiH4、Si2H6、Si3H8、SiCl4、SiHCl3、Si2Cl6、SiH2Cl2、SiH3Cl中的一种或多种;所述气态碳源包括C2H2、CH4、C2H6、C2H4、CO和CO2中的一种或多种;所述气态硅源和所述气态碳源的流量为5sccm~60sccm,所述混合气体的通气时间为60min~480min。
可选地,所述气相沉积完成后得到硅碳复合材料,将所述硅碳复合材料与固态碳源混合后在400℃-1000℃下烧结,得到所述硅碳电极材料;所述固态碳源包括沥青和高分子有机物。
可选地,所述硅碳电极材料为本申请第一方面提供的所述硅碳电极材料。
第三方面,本申请提供了一种负极,包括如第一方面所述的硅碳电极材料或如第二方面所述的制备方法制得的硅碳电极材料。
第四方面,本申请提供了一种电池,包括如第三方面所述的负极。
第五方面,本申请提供了一种包括如第四方面所述电池的装置,该装置为用电设备或储能系统。
附图说明
图1为本申请一实施例提供的多孔碳的结构示意图。
图2为本申请一实施例提供的硅碳电极材料的制备方法的流程图。
图3为本申请实施例1的硅碳电极材料的XRD表征图。
图4为本申请各实施例和对比例电池的膨胀率对比图。
具体实施方式
下面将结合本申请实施例中的附图,对本申请实施例中的技术方案进行清楚、完整地描述,显然,所描述的实施例仅仅是本申请一部分实施例,而不是全部的实施例。基于本申请中的实施例,本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例,都属于本申请保护的范围。
硅因具有较高的理论比容量被认为是最具潜力的高能量密度电池负极材料,但硅在金属离子脱嵌过程中体积膨胀显著,电极材料易发生粉化、脱落,降低电池的循环性能。为降低 硅的膨胀效应,提高电极材料的结构稳定性,本申请提供了一种硅碳电极材料,该硅碳电极材料包括多孔碳和分布在多孔碳孔道中的硅碳复合纳米颗粒,该多孔碳具有孔道结构,硅碳复合纳米颗粒分布在孔道之中,多孔碳可对硅碳复合纳米颗粒提供有力的支撑,缓解硅体积膨胀引起的性能衰减,而且该结构还能够有效地提高电极材料的电导率,促进电子的传输。
本申请一些实施方式中,硅碳复合纳米颗粒包括硅原子和硅原子之间成键形成硅颗粒、碳原子和碳原子之间成键形成的碳以及硅原子和碳原子之间成键形成的碳化硅。硅碳复合纳米颗粒中的碳能够提升硅的电化学活性,使硅的容量能够充分发挥,并提高电极材料的倍率性能。在一些实施例中,硅碳电极材料包括无定形碳;可选地,所述硅碳电极材料中无定形碳的质量百分含量为50%~80%。在一些实施例中,硅碳复合纳米颗粒中的碳为无定形碳(如硬碳等)。
本申请一些实施方式中,硅碳复合纳米颗粒中的硅原子和碳原子堆积形成四面体结构,硅原子周围有四个碳原子,碳原子周围有四个硅原子,碳原子和硅原子间隔分布,使得硅碳复合纳米颗粒内部形成导电网络,从而大大提升硅颗粒的导电性。
本申请一些实施方式中,硅碳复合纳米颗粒中,硅原子与碳原子的质量比为(1.5~4):1,硅原子与碳原子的质量比具体可以但不限于为1.5:1、2:1、3:1或4:1。控制硅原子与碳原子的质量比在上述范围可以保证硅碳电极材料具有较高的比容量和倍率性能。
本申请一些实施方式中,多孔碳孔道的平均深度为50nm~150nm。其中,多孔碳孔道的深度指的是多孔碳孔道在其延伸方向上的长度,多孔碳孔道的孔径指的是孔道在外表面上的直径,多孔碳孔道的平均深度具体可以但不限于为50nm、80nm、100nm、120nm、150nm。本申请一些实施方式中,孔道的平均孔径为10nm~30nm。多孔碳孔道的平均孔径具体可以但不限于为10nm、15nm、20nm或30nm。该结构的多孔碳不仅有利于将硅碳复合纳米颗粒充分的分散开,从而避免硅膨胀的应力过于集中、提高材料的结构稳定性,而且还有利于减轻纳米硅氧化的问题。本申请一些实施方式中,多孔碳为镂空结构,内部孔道为均匀分布的柱状结构,即孔道的截面为圆形。
本申请一些实施方式中,多孔碳包括人造石墨、天然石墨或硬碳中的一种或多种,硅碳复合纳米颗粒可通过共价键与多孔碳相作用,形成结构稳定的硅碳电极材料。
本申请一些实施方式中,硅碳复合纳米颗粒中硅颗粒的平均粒径小于或等于4nm,在一些实施例中,硅颗粒的平均粒径小于或等于4nm且大于或等于0.5nm。硅颗粒的平均粒径具体可以但不限于为0.5nm、1nm、2nm、3nm或4nm。较小尺寸的硅颗粒不仅有利于锂离子快速地脱出或嵌入,从而改善材料的倍率性能,并且小尺寸的硅颗粒体积膨胀粉化效应弱,有利于提高电极材料的结构稳定性。
本申请一些实施方式中,所述硅颗粒包括非晶硅;本申请一些实施方式中,所述硅颗粒为非晶硅。相比于晶体硅,非晶硅嵌锂后膨胀率低,结构稳定。
本申请一些实施方式中,多孔碳孔道中硅碳复合纳米颗粒的总体积与碳孔道的孔容之比为1:(1.01~1.05),其中,硅碳复合纳米颗粒的总体积单位为nm2,碳孔道的孔容单位为nm2。控制硅碳复合纳米颗粒尺寸与碳孔道孔容的比例有利于为硅颗粒的体积膨胀提供缓冲空间,减轻硅颗粒膨胀对材料整体的影响,抑制材料的粉化,并保证材料整体具有较高的容量。
本申请一些实施方式中,硅碳电极材料还包括包覆在多孔碳和硅碳复合纳米颗粒表面的碳包覆层;本申请一些实施方式中,碳包覆层包括无定形碳和石墨化碳中的一种或多种。碳 包覆层可以进一步提高硅碳电极材料的结构稳定性和导电性。在一些实施例中,碳包覆层为无定形碳包覆层,无定形碳结构稳定且倍率性能好。本申请一些实施方式中,碳包覆层的厚度为10nm~200nm,碳包覆层在硅碳电极材料中的质量百分含量为5%~10%。
本申请一些实施方式中,在硅碳电极材料中,硅元素的质量百分含量为20%~50%,碳元素的质量百分含量为50%~80%,碳元素的含量可通过热重分析仪测得,硅元素的含量可通过以下方法测得:将硅碳电极材料用氢氟酸溶解后,采用ICP元素分析测量电极材料中硅元素的含量。硅元素在硅碳电极材料中的质量百分含量具体可以但不限于为20%、30%、33%、35%、37%、40%、45%或50%。在一些实施例中,硅碳电极材料中的无定形碳的质量百分含量为10%~20%。控制碳的含量可以保证硅碳电极材料具有良好的离子导电性,有利于提升硅碳电极材料对离子的导通性,降低材料极化,促进离子的迁移,使电池具有良好的倍率性能。本申请一些实施方式中,硅碳电极材料的Dv50为12μm~18μm,硅碳电极材料的Dv50具体可以但不限于为12μm、14μm、15μm、16μm或18μm。
本发明提供的硅碳电极材料中,多孔碳的孔道结构可将小尺寸的硅碳复合纳米颗粒分散开并为硅在充放电过程中的体积变化提供缓冲空间,提高材料的结构稳定性,硅碳复合纳米颗粒中的碳原子可以有效提升电极材料的电化学活性,使硅材料具有良好的倍率性能和比容量发挥。将其应用在二次电池中能够提高二次电池的倍率性能和循环性能,有利于电池的长期使用。
如图2所示,本申请还提供了上述硅碳电极材料的制备方法,包括:
201,对多孔碳通气态硅源和气态碳源进行气相沉积,得到硅碳电极材料。其中,气态硅源和气态碳源的流量比为(0.5~2):1,以及气相沉积的温度为300℃~630℃。
请参阅图1,图1为本申请一实施例提供的多孔碳的结构示意图,多孔碳的表面为多孔结构。在一些实施方式中,多孔碳的Dv50为12μm~18μm,多孔碳中孔道的平均深度为50nm~150nm,孔道的平均孔径为10nm~30nm,多孔碳的孔隙率为5%~30%。控制多孔碳的尺寸结构有利于硅碳复合纳米颗粒在多孔碳的孔道中均匀沉积,以促进形成小尺寸的硅碳复合纳米颗粒。本申请一些实施方式中,多孔碳包括人造石墨、天然石墨或硬碳中的一种或多种。本申请一些实施方式中,多孔碳的制备方法包括:提供碳材料,碳材料包括人造石墨、天然石墨或硬碳的一种或者多种;将碳材料置于热处理设备中,向热处理设备通入二氧化碳以对碳材料进行刻蚀,其中,刻蚀的温度为200℃~800℃,二氧化碳气体的流通量为10sccm~50sccm,热处理设备可以是回转炉,回转炉的转速为3°/min~12°/min。
本申请中,采用气态硅源和气态碳源进行气相沉积时,气态硅源裂解形成硅原子,气态碳源裂解形成碳原子,由于Si-C键的成键能低于Si-Si键的成键能,故气态碳源裂解生成碳原子能够与硅原子预先形成Si-C键,抑制Si-Si键的形成,阻止沉积硅成核后的长大,从而形成小尺寸的硅碳复合纳米颗粒。本申请实施方式中,气态硅源和气态碳源的流量比为(0.5~2):1,气态硅源和气态碳源的流量比具体可以但不限于为0.5:1、0.8:1、1:1、1.5:1或2:1。控制气态硅源和气态碳源的流量比能够保证碳原子和硅原子有序沉积形成硅碳复合纳米颗粒,从而促进硅颗粒容量的发挥。
本申请一些实施方式中,气态硅源的流量为5sccm~60sccm,气态硅源的流量具体可以但不限于为5sccm、10sccm、20sccm、30sccm、40sccm或60sccm。本申请一些实施方式中,气态碳源的流量为5sccm~60sccm,气态碳源的流量具体可以但不限于为5sccm、10sccm、 20sccm、30sccm、40sccm或60sccm。本申请一些实施方式中,混合气体的通气时间为60min~480min。控制气体的流量可以促使硅纳米颗粒均匀沉积在多孔碳的孔道中。
本申请实施方式中,气相沉积的温度为300℃~630℃,气相沉积的温度具体可以但不限于为300℃、400℃、450℃、500℃、600℃或630℃。在该温度下进行气相沉积能够形成无定形结构的硅,并且碳原子可以有效地与硅复合形成硅碳复合纳米颗粒。本申请一些实施方式中,气相沉积的温度为300℃~500℃,考虑到低温下碳源裂解反应速率降低,影响碳源利用率,故在多孔碳中添加少量的催化剂,催化剂包括氧化铜、氧化镍或者铂金属催化剂促进碳源的裂解。
本申请一些实施例中,气态硅源包括SiH4、Si2H6、Si3H8、SiCl4、SiHCl3、Si2Cl6、SiH2Cl2、SiH3Cl中的一种或多种;所述气态碳源包括C2H2、CH4、C2H6、C2H4、CO和CO2中的一种或多种。在一些实施例中,气态硅源为SiH4,气态碳源为C2H4。采用SiH4和C2H4的混合气体进行气相沉积时,一方面气体裂解效率高,可以均匀填充在多孔碳的孔道中,形成密实结构材料;另一方面裂解产生的氢气可以回收利用,节约能源。
本申请一些实施方式中,所述硅碳电极材料还包括包覆在所述多孔碳和所述硅碳复合纳米颗粒表面的碳包覆层,此时,可将多孔碳进行气相沉积处理得到硅碳复合纳米颗粒分布在多孔碳孔道中的硅碳复合材料,再进一步对硅碳复合材料进行碳包覆,在一些实施例中,碳包覆的方法包括:将硅碳复合材料与固态碳源在搅拌罐中搅拌均匀混合得到混合物,再将混合物在真空管式炉中以400℃~1000℃的温度进行真空烧结3h~8h形成碳包覆层,其中,硅碳复合材料与固态碳源的质量比为(9-19):1,搅拌转速为300r/min~800r/min,搅拌时间为30min~180min,固态碳源包括沥青和高分子有机物中的一种或多种,沥青包括石油沥青、煤焦油沥青或天然沥青中的一种或多种,高分子有机物包括醇、树脂和糖中的一种或多种,醇包括聚糠醇或聚乙烯醇中的一种或多种,树脂包括环氧树脂、酚醛树脂和密胺树脂中的一种或多种,糖包括葡萄糖和蔗糖中的一种或多种。
在一些实施例中,在硅碳复合材料表面形成碳包覆层后,进一步在碳包覆层表面制备第二碳包覆层。第二碳包覆层的制备方法包括:将具有碳包覆层的硅碳复合材料置于热处理设备中进行气相碳沉积,气相碳沉积的碳源包括甲烷、乙烯、乙炔、丙烷或丙烯中的一种或多种,气相碳沉积的温度为300-900℃。在一些实施例中,在300-600℃下进行气相沉积形成无定形碳包覆层,无定形碳包覆层具有良好的倍率性能。
本申请一些实施例中,硅碳电极材料的制备方法包括:将多孔碳放置在真空不锈钢管式炉膛中,真空不锈钢管式炉具有两个通气口,可以同时进行通气反应。管式炉中通入气态硅源和气态碳源,气态硅源和气态碳源的流量比为(0.5~2):1,气态硅源和气态碳源在真空管式炉中发生热分解并共沉积生成硅碳复合纳米颗粒,并且硅碳复合纳米颗粒沉积在多孔碳的孔道中,形成硅碳复合材料;将硅碳复合材料与固态碳源在搅拌罐中搅拌均匀混合后放置在真空管式炉中真空烧结,形成碳包覆层,并得到硅碳电极材料。
本申请提供的硅碳电极材料的制备方法能够得到新型结构的电极材料,该方法工艺简单,有利于规模化生产。
本申请还提供了一种负极,该负极包括本申请的硅碳电极材料。例如,该负极包括集流体和设置在集流体上的负极材料层,其中,负极材料层包括本申请的硅碳电极材料。本申请中,负极材料层的制备可以是将硅碳电极材料、导电剂、粘结剂和溶剂混合形成负极浆料, 再将负极浆料经涂覆、干燥后得到负极材料层。在配制负极浆料时,可以先将粘结剂与溶剂混合,充分搅拌后,再加入导电剂,经搅拌后再加入硅碳电极材料,搅拌后过筛得到负极浆料。其中,导电剂、粘结剂和溶剂为电池领域的常规选择。例如,粘结剂可以选自聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚乙烯醇(PVA)、丁苯橡胶(SBR)、聚丙烯腈(PAN)、聚酰亚胺(PI)、聚丙烯酸(PAA)、聚丙烯酸酯、聚烯烃、羧甲基纤维素钠(CMC)和海藻酸钠中的一种或多种。导电剂可以选自碳纳米管、炭黑以及石墨烯中的一种或多种。
本申请还提供了一种电池。本申请一些实施方式中,该电池包括正极、负极、电解液以及位于正极与负极之间的隔膜,其中,负极包括本申请提供的负极。本申请一些实施方式中,该电池包括正极、负极以及位于正极与负极之间的固态电解质或半固态电解质。本申请一些实施方式中,所述电池为二次电池,二次电池可以是锂离子电池、钠离子电池、钾离子电池、铝离子电池、锌离子电池或镁离子电池中的任意一种。
本申请中,二次电池的正极可以是本领域公知的任意正极。在一些实施例中,正极的活性材料为能够可逆脱出和嵌入锂离子的材料;在一些实施例中,正极的活性材料为能够可逆脱出和嵌入钠离子的材料;在一些实施例中,正极的活性材料为能够可逆脱出和嵌入钾离子的材料;在一些实施例中,正极的活性材料为能够可逆脱出和嵌入镁离子的材料。本申请中,二次电池的隔膜可以是本领域技术人员公知的任意隔膜,例如隔膜可以是聚烯烃微多孔膜、聚对苯二甲酸乙二醇酯、聚乙烯毡、玻璃纤维毡或超细玻璃纤维纸中的一种或多种。
本申请中,二次电池的电解液包括电解质锂盐在非水溶剂中形成的溶液。本申请实施方式中,电解质锂盐包括六氟磷酸锂(LiPF6)、高氯酸锂(LiClO4)、四氟硼酸锂(LiBF4)、六氟砷酸锂(LiAsF6)、六氟硅酸锂(Li2SiF6)、四苯基硼酸锂(LiB(C6H5)4)、氯化锂(LiCl)、溴化锂(LiBr)、氯铝酸锂(LiAlCl4)、氟烃基磺酸锂(LiC(SO2CF3)3)、LiCH3SO3、LiN(SO2CF3)2和LiN(SO2C2F5)2中的一种或多种。本申请一些实施方式中,非水溶剂包括链状酸酯和环状酸酯中的一种或多种。本申请一些实施方式中,链状酸酯包括碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、碳酸甲丙酯(MPC)和碳酸二丙酯(DPC)中的一种或多种。本申请一些实施方式中,链状酸酯包括含氟、含硫或含不饱和键的链状有机酯类。本申请一些实施方式中,环状酸酯包括碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸亚乙烯酯(VC)、γ-丁内酯(γ-BL)和磺内酯中的一种或多种。本申请一些实施方式中,环状酸酯包括含氟、含硫或含不饱和键的环状有机酯。本申请一些实施方式中,非水溶剂包括链状醚和环状醚溶液中的一种或多种。本申请一些实施方式中,环状醚包括四氢呋喃(THF)、2-甲基四氢呋喃(2-MeTHF)、1,3-二氧戊烷(DOL)和4-甲基-1,3-二氧环戊烷(4-MeDOL)中的一种或多种。本申请一些实施方式中,环状醚包括含氟、含硫或含不饱和键的环状有机醚。本申请一些实施方式中,链状醚包括二甲氧基甲烷(DMM)、1,2-二甲氧基乙烷(DME)、1,2-二甲氧基丙烷(DMP)和二甘醇二甲醚(DG)中的一种或多种。本申请一些实施方式中,链状醚包括含氟、含硫或含不饱和键的链状有机醚。本申请实施方式中,电解液中电解质锂盐的浓度为0.1mol/L-15mol/L。本申请一些实施方式中,电解质锂盐的浓度为1mol/L-10mol/L。
本申请实施方式中,电池的制备可以采用叠片工艺或卷绕工艺中的任意一种。
本申请还提供了一种包括本申请提供的电池的装置,该装置例如可以为用电设备或储能系统,电池为用电设备或储能系统供电;用电设备可以为交通工具、电子设备等,交通工具例如可以为车辆、船舶等,电子设备例如可以为3C产品(计算机类、通信类和消费类电子 产品)等。
下面分多个实施例对本申请技术方案进行进一步的说明。
实施例1
一种硅碳电极材料的制备方法,包括:
将石墨置于回转炉中,通入二氧化碳气体对石墨进行刻蚀形成多孔碳,其中,回转炉的转速为6°/min,温度为600℃,二氧化碳气体流通量为15sccm,反应的时间为300min。
将30g的多孔碳放在真空不锈钢管式炉膛中,管式炉加热到475℃,向管式炉中通入甲硅烷和乙烯,甲硅烷气体流通量为10sccm,乙烯气体流通量为20sccm,甲硅烷和乙烯通气气流量比为0.5:1,通气时间为240min,得到硅碳复合材料;取100g硅碳复合材料与10g沥青在搅拌罐中搅拌得到混合物,搅拌转速为550r/min,时间为60分钟;将混合物放置在真空管式炉中以600℃进行真空烧结6h,得到硅碳电极材料。
负极极片的制备:将硅碳电极材料、羧甲基纤维素钠、乙炔黑以8:1:1的质量比混合得到负极浆料,用刮刀将负极浆料涂敷于铜箔上,经烘干、辊压并裁切后得到负极极片。
电池的制备:以锂片作为对电极片、聚乙烯/聚丙烯(PE/PP)复合隔膜作为隔膜,采用本领域常规方法做成扣式电池,实施例1的电池命名为S1。
实施例2
采用与实施例1相同的方法制备得到多孔碳,将30g的多孔碳放在真空不锈钢管式炉膛中,管式炉加热到475℃,向管式炉中通入甲硅烷和乙烯,甲硅烷气体流通量为20sccm,乙烯气体流通量为20sccm,甲硅烷和乙烯通气气流量比为1:1,通气时间为120min,得到硅碳复合材料;取100g硅碳复合材料与10g沥青在搅拌罐中搅拌得到混合物,搅拌转速为550r/min,时间为60分钟;将混合物放置在真空管式炉中以600℃进行真空烧结6h,得到硅碳电极材料。
采用与实施例1相同的方法制备得到负极极片和电池,实施例2的电池命名为S2。
实施例3
采用与实施例1相同的方法制备得到多孔碳,将30g的多孔碳放在真空不锈钢管式炉膛中,管式炉加热到475℃,向管式炉中通入甲硅烷和乙烯,甲硅烷气体流通量为40sccm,乙烯气体流通量为20sccm,甲硅烷和乙烯通气气流量比为2:1,通气时间为60min,得到硅碳复合材料;取100g硅碳复合材料与10g沥青在搅拌罐中搅拌得到混合物,搅拌转速为550r/min,时间为60分钟;将混合物放置在真空管式炉中以600℃进行真空烧结6h,得到硅碳电极材料。
采用与实施例1相同的方法制备得到负极极片和电池,实施例3的电池命名为S3。
实施例4
采用与实施例1相同的方法制备得到硅碳复合材料;取100g硅碳复合材料与10g沥青在搅拌罐中搅拌得到混合物,搅拌转速为550r/min,时间为60分钟;将混合物放置在真空管式炉中以600℃进行真空烧结6h,得到包覆有无定形碳层的硅碳复合材料,将包覆有无定形碳层的硅碳复合材料放置到真空回转炉中,向真空回转炉通入甲烷气体进行气相包覆,回转炉的转速为6°/min,温度为800℃,甲烷气体流通量为20sccm,得到硅碳电极材料。
采用与实施例1相同的方法制备得到负极极片和电池,实施例4的电池命名为S4。
实施例5
将硬碳置于回转炉中,通入二氧化碳气体对硬碳进行刻蚀形成多孔碳,其中,回转炉的转速为15°/min,温度为900℃,二氧化碳气体流通量为60sccm,反应的时间为300min。
采用与实施例1相同的方法制备得到硅碳电极材料、负极极片和电池,实施例5的电池命名为S5。
实施例6
实施例6采用与实施例1相同的方法制备多孔碳并对多孔碳进行气相沉积,向通入气态硅源和气态碳源后在多孔碳的孔道中沉积硅碳复合纳米颗粒,得到硅碳复合材料,即得到硅碳电极材料。
采用与实施例1相同的方法制备得到负极极片和电池,实施例6的电池命名为S6。
实施例7
采用与实施例1相同的方法制备得到多孔碳,将30g的多孔碳放在真空不锈钢管式炉膛中,管式炉加热到475℃,向管式炉中通入甲硅烷和乙烯,甲硅烷气体流通量为80sccm,乙烯气体流通量为80sccm,甲硅烷和乙烯通气气流量比为1:1,通气时间为60min,得到硅碳复合材料;取100g硅碳复合材料与10g沥青在搅拌罐中搅拌得到混合物,搅拌转速为550r/min,时间为60分钟;将混合物放置在真空管式炉中以600℃进行真空烧结6h,得到硅碳电极材料。
采用与实施例1相同的方法制备得到负极极片和电池,实施例7的电池命名为S7。
实施例8
将石墨置于回转炉中,通入二氧化碳气体对石墨进行刻蚀形成多孔碳,其中,回转炉的转速为12°/min,温度为400℃,二氧化碳气体流通量为15sccm,反应的时间为300min。
将30g的多孔碳放在真空不锈钢管式炉膛中,管式炉加热到475℃,向管式炉中通入甲硅烷和乙烯,甲硅烷气体流通量为10sccm,乙烯气体流通量为20sccm,甲硅烷和乙烯通气气流量比为0.5:1,通气时间为240min,得到硅碳复合材料;取100g硅碳复合材料与10g沥青在搅拌罐中搅拌得到混合物,搅拌转速为550r/min,时间为60分钟;将混合物放置在真空管式炉中以600℃进行真空烧结6h,得到硅碳电极材料。
采用与实施例1相同的方法制备得到负极极片和电池,实施例8的电池命名为S8。
实施例9
将石墨置于回转炉中,通入二氧化碳气体对石墨进行刻蚀形成多孔碳,其中,回转炉的转速为10°/min,温度为600℃,二氧化碳气体流通量为35sccm,反应的时间为300min。
将30g的多孔碳放在真空不锈钢管式炉膛中,管式炉加热到475℃,向管式炉中通入甲硅烷和乙烯,甲硅烷气体流通量为10sccm,乙烯气体流通量为20sccm,甲硅烷和乙烯通气气流量比为0.5:1,通气时间为240min,得到硅碳复合材料;取100g硅碳复合材料与10g沥青在搅拌罐中搅拌得到混合物,搅拌转速为550r/min,时间为60分钟;将混合物放置在真空管式炉中以600℃进行真空烧结6h,得到硅碳电极材料。
采用与实施例1相同的方法制备得到负极极片和电池,实施例9的电池命名为S9。
实施例10
将石墨置于回转炉中,通入二氧化碳气体对石墨进行刻蚀形成多孔碳,其中,回转炉的转速为15°/min,温度为600℃,二氧化碳气体流通量为10sccm,反应的时间为300min。
将30g的多孔碳放在真空不锈钢管式炉膛中,管式炉加热到475℃,向管式炉中通入甲 硅烷和乙烯,甲硅烷气体流通量为10sccm,乙烯气体流通量为20sccm,甲硅烷和乙烯通气气流量比为0.5:1,通气时间为240min,得到硅碳复合材料;取100g硅碳复合材料与10g沥青在搅拌罐中搅拌得到混合物,搅拌转速为550r/min,时间为60分钟;将混合物放置在真空管式炉中以600℃进行真空烧结6h,得到硅碳电极材料。
采用与实施例1相同的方法制备得到负极极片和电池,实施例10的电池命名为S10。
对比例1
对比例1是采用商品化的硅碳产品,硅碳产品的结构为类石榴结构,该硅碳产品中纳米硅是由微米尺度的硅颗粒砂磨制成纳米尺度,纳米硅的平均粒径为100nm。该硅碳产品是通过将纳米硅分散在石墨和无定形碳中得到的。取100g硅碳复合材料与10g沥青在搅拌罐中搅拌得到混合物,搅拌转速为550r/min,时间为60分钟;将混合物放置在真空管式炉中以600℃进行真空烧结6h,得到该硅碳产品。
采用与实施例1相同的方法制备得到负极极片和电池,对比例1的电池命名为D1。
对比例2
采用与实施例1相同的方法制备得到多孔碳,将30g的多孔碳放在真空不锈钢管式炉膛中,管式炉加热到475℃,向管式炉中通入甲硅烷和氮气,甲硅烷气体流通量为10sccm,氮气气体流通量为50sccm,甲硅烷和氮气通气气流量比为1:5,通气时间为240min,得到未包覆的硅碳材料;取100g未包覆的硅碳材料与10g沥青在搅拌罐中搅拌得到混合物,搅拌转速为550r/min,时间为60分钟;将混合物放置在真空管式炉中以600℃进行真空烧结6h,得到硅碳电极材料。
采用与实施例1相同的方法制备得到负极极片和电池,对比例2的电池命名为D2。
对比例3
对比例3是直接对石墨进行气相沉积(未对石墨进行刻蚀),采用与实施例1相同的方法制备得到硅碳电极材料、负极极片和电池,对比例3的电池命名为D3。
效果实施例
为验证本申请制得的硅碳电极材料和电池性能,本申请还提供了效果实施例。
1)采用扫描电镜对各实施例的硅碳电极材料和各对比例的电极材料进行表征,材料的结构参数如表1所示。
表1实施例的硅碳电极材料和对比例的电极材料结构参数表

由表1可以看出本申请通过采用特定结构的多孔碳并控制气相沉积条件能够获得较小尺寸的硅纳米颗粒,并且硅纳米颗粒分散在多孔碳的孔道间,不仅有效地分散了硅碳电极材料中硅颗粒膨胀的应力,而且有效缓解小颗粒硅的团聚现象,使得材料具有良好的结构稳定性和电化学性能。
实施例2和3中硅源与碳源的流量比较实施例1更大,故所得硅碳电极材料中硅纳米颗粒的粒径较大。实施例4的硅碳电极材料进一步进行了气相沉积包覆碳,所得的硅碳电极材料粒径相对较大;实施例5中对碳材料进行刻蚀时二氧化碳气体流通量较大,所得多孔碳孔道的孔道尺寸较大,在气相沉积后,所得硅纳米颗粒的尺寸较大。实施例6的硅碳电极材料不含有碳包覆层,硅碳电极材料的粒径相对较小;实施例7的硅碳电极材料在制备时气体流量较大,气体裂解后容易团聚,导致纳米硅颗粒的尺寸较大;实施例8中对碳材料进行刻蚀时管式炉内温度较低,所得多孔碳孔道的孔道尺寸较小,在气相沉积后,所得硅纳米颗粒尺寸接近多孔碳孔道孔径。
对比例2进行气相沉积采用的是气态硅源和载气的混合体系,即混合气体中不含有气态碳源,其所得的硅纳米颗粒的粒径较大,电极材料的膨胀效应仍十分显著,对比例3是直接对碳材料进行沉积,气体裂解后沉积在碳材料的表面,导致纳米硅的团聚,硅的膨胀效应较强。
2)采用热重分析仪对各实施例的硅碳电极材料和各对比例的电极材料中碳含量进行表征,将硅碳电极材料用氢氟酸溶解后,采用ICP元素分析测量电极材料中硅的含量,表征结果如表2所示。
表2实施例的硅碳电极材料和对比例的电极材料硅碳含量表
表2中,实施例1、实施例2和实施例3中,甲硅烷和乙烯通气气流量比不同,随着甲硅烷含量的增加,硅碳电极材料中硅的含量也增大,实施例4是在实施例1的基础上再进行CVD碳包覆,CVD碳包覆碳含量约4%,故实施例4碳含量增加;实施例5在碳材料刻蚀过程中二氧化碳气体流通量较多,刻蚀效果差,但是基本不影响硅含量和碳含量;实施例6中硅碳材料没有进行碳包覆,故碳含量会降低,相应的硅含量增加;实施例7中硅和碳的沉积过程甲硅烷和乙烯气体流通量增加,多孔碳含量固定,故硅含量增加;实施例8中,多孔碳的平均孔径和孔深较小,硅沉积过程会有堵孔现象,硅沉积的性能较差,硅的含量有所降低。
对比例1为商业化硅碳材料,砂磨获得纳米硅与碳材料复合,复合过程纳米硅的含量可以调控,掺混50%硅含量;对比例2沉积过程没有乙烯气体,故硅含量较高;对比例3与实施例1比石墨没后造孔,对硅含量影响较小。
3)采用X射线粉末衍射仪对实施例1的硅碳电极材料进行表征,请参阅图3,图3为本申请实施例1的硅碳电极材料的XRD表征图,由图3可以看出,硅碳电极材料中硅为无定形硅。
4)采用LANHE蓝电电池测试系统对各实施例和对比例的电池进行电化学性能测试,测试条件具体为:将电池在常温下以0.01C的电流恒流放电至0.005V,然后以0.1C恒流充电至1.5V,该过程记为循环1圈。记录电池的首次放电容量和首次充电容量,首次充电容量对应首次可逆容量;计算首次放电效率(%)=(首次充电容量/首次放电容量)×100%。循环100圈后剩余容量是指电池循环100圈后的充电容量;循环100圈后剩余容量保持率=循环100圈后剩余容量/首次充电容量。各实施例和对比例的电池性能如表3所示。
表3实施例1-10和对比例1-3的电池电化学性能表

表3中,实施例1和实施例4的硅碳电极材料中硅纳米颗粒粒径较小,故电池的剩余容量保持率较高,实施例3的硅碳电极材料中硅的含量较高,故电池具有较高的首次可逆容量,实施例6没有进行包覆,导致材料导电性差及有裸露的硅颗粒存在硅碳材料表面,容量和首效都相对较低,容量保持率较差,实施例5和7的硅碳电极材料中,硅颗粒粒径较大,其容量保持率较差,实施例8的硅碳电极材料中,硅在沉积过程中出现堵孔现象,导致硅颗粒在碳孔道中分散不均匀,多孔碳内存在大量的空腔,硅材料的膨胀和界面副反应导致容量保持率较差。
5)对各实施例和对比例的电池进行膨胀测试,测试条件具体为:在装配扣电之前用千分尺测量每组样品极片的原始厚度。循环50圈后,放电至0%SOC,拆解扣电,将负极片取出,并用DMC溶液清洗干净,晾干后进行厚度测试,并计算膨胀率,测试结果请参阅表4。
表4实施例1-10和对比例1-3的电池膨胀性能表
请参阅图4,图4为本申请各实施例和对比例电池的膨胀率对比图,由表4和图4可以看出,采用本申请的硅碳电极材料制备得到的极片具有更好的稳定性,电池的膨胀率低。对于各实施例,实施例3中硅碳复合纳米颗粒在制备时甲硅烷相对乙烯的含量过高,形成硅碳复合纳米颗粒中硅颗粒的尺寸较大,材料膨胀效应较强;实施例5中硅碳复合纳米颗粒在制备时多孔碳的孔径过大,形成硅碳复合纳米颗粒中硅颗粒的尺寸较大,材料膨胀效应较强;实施例7中硅碳复合纳米颗粒在制备时气体流量过大,形成硅颗粒的尺寸较大,材料膨胀效应较强。
由此可以看出,将本申请的硅碳电极材料应用在电池中可以有效地提高电池的循环性能和倍率性能。
以上所述是本申请的优选实施方式,但并不能因此而理解为对本申请范围的限制。应当指出,对于本技术领域的普通技术人员来说,在不脱离本申请原理的前提下,还可以做出若干改进和润饰,这些改进和润饰也视为本申请的保护范围。

Claims (25)

  1. 一种硅碳电极材料,其特征在于,所述硅碳电极材料包括多孔碳和分布在所述多孔碳的孔道中的硅碳复合纳米颗粒;所述硅碳复合纳米颗粒中至少部分硅原子和至少部分碳原子之间形成硅碳键。
  2. 如权利要求1所述的硅碳电极材料,其特征在于,所述硅碳复合纳米颗粒包括硅颗粒、碳和碳化硅。
  3. 如权利要求1或2所述的硅碳电极材料,其特征在于,所述孔道的平均深度为50nm~150nm;所述孔道的平均孔径为10nm~30nm。
  4. 如权利要求1-3任一项所述的硅碳电极材料,其特征在于,所述多孔碳的孔隙率为5%~30%。
  5. 如权利要求1-4任一项所述的硅碳电极材料,其特征在于,所述多孔碳包括人造石墨、天然石墨和硬碳中的一种或多种。
  6. 如权利要求1-5任一项所述的硅碳电极材料,其特征在于,所述硅颗粒的平均粒径小于或等于4nm。
  7. 如权利要求1-3任一项所述的硅碳电极材料,其特征在于,所述硅颗粒包括非晶硅。
  8. 如权利要求1-7任一项所述的硅碳电极材料,其特征在于,所述硅碳电极材料还包括包覆在所述多孔碳和所述硅碳复合纳米颗粒表面的碳包覆层。
  9. 如权利要求8所述的硅碳电极材料,其特征在于,所述碳包覆层包括无定形碳和石墨化碳中的至少一种。
  10. 如权利要求8或9所述的硅碳电极材料,其特征在于,所述碳包覆层的厚度为10nm~200nm,所述碳包覆层在所述硅碳电极材料中的质量百分含量为5%~10%。
  11. 如权利要求8所述的硅碳电极材料,其特征在于,所述硅碳电极材料还包括包覆在所述碳包覆层表面的第二碳包覆层。
  12. 如权利要求1-11任一项所述的硅碳电极材料,其特征在于,所述硅碳电极材料中,硅元素的质量百分含量为20%~50%,碳元素的质量百分含量为50%~80%。
  13. 如权利要求1-12任一项所述的硅碳电极材料,其特征在于,所述硅碳电极材料包括无定形碳;可选地,所述硅碳电极材料中无定形碳的质量百分含量为50%~80%。
  14. 如权利要求1-13任一项所述的硅碳电极材料,其特征在于,所述硅碳电极材料的Dv50为12μm~18μm。
  15. 如权利要求1-14任一项所述的硅碳电极材料,其特征在于,所述硅碳复合纳米颗粒中的硅原子和碳原子堆积成四面体结构。
  16. 如权利要求1-15任一项所述的硅碳电极材料,其特征在于,所述硅碳复合纳米颗粒中的硅原子与碳原子的质量比为(1.5~4):1。
  17. 如权利要求1-16任一项所述的硅碳电极材料,其特征在于,所述硅碳复合纳米颗粒的总体积与所述碳孔道的孔容之比为1:(1.01~1.05)。
  18. 一种硅碳电极材料的制备方法,其特征在于,包括:
    对多孔碳通气态硅源和气态碳源进行气相沉积,得到硅碳电极材料(201),其中,所述气态硅源和所述气态碳源的流量比为(0.5~2):1;所述气相沉积的温度为300℃~630℃。
  19. 如权利要求18所述的制备方法,其特征在于,所述气态硅源包括SiH4、Si2H6、Si3H8、SiCl4、SiHCl3、Si2Cl6、SiH2Cl2和SiH3Cl中的一种或多种;所述气态碳源包括C2H2、CH4、C2H6、C2H4、CO和CO2中的一种或多种;所述气态硅源和所述气态碳源的流量为5sccm~60sccm,所述气态硅源和所述气态碳源的通气时间为60min~480min。
  20. 如权利要求18或19所述的制备方法,其特征在于,所述气相沉积完成后得到硅碳复合材料,将所述硅碳复合材料与固态碳源混合后在400℃-1000℃下烧结,得到所述硅碳电极材料;所述固态碳源包括沥青和高分子有机物中的一种或多种。
  21. 如权利要求18-20任一项所述的制备方法,其特征在于,所述多孔碳的制备方法包括:将碳材料置于热处理设备中,向热处理设备通入二氧化碳以对碳材料进行刻蚀,其中,刻蚀的温度为200℃~800℃,二氧化碳气体的流通量为10sccm~50sccm;所述碳材料包括人造石墨、天然石墨和硬碳的一种或者多种。
  22. 如权利要求18-21任一项所述的制备方法,其特征在于,所述硅碳电极材料为权利要求1-15任一项所述的硅碳电极材料。
  23. 一种负极,包括如权利要求1-17任一项所述的硅碳电极材料或如权利要求18-22任一项所述的制备方法制得的硅碳电极材料。
  24. 一种电池,其特征在于,包括如权利要求23所述的负极。
  25. 一种包括如权利要求24所述的电池的装置,该装置为用电设备或储能系统。
PCT/CN2023/116055 2022-08-31 2023-08-31 硅碳电极材料、其制备方法、负极、电池和装置 WO2024046410A1 (zh)

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