WO2023116020A1 - Negative electrode material, preparation method therefor, and application thereof - Google Patents

Negative electrode material, preparation method therefor, and application thereof Download PDF

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WO2023116020A1
WO2023116020A1 PCT/CN2022/115296 CN2022115296W WO2023116020A1 WO 2023116020 A1 WO2023116020 A1 WO 2023116020A1 CN 2022115296 W CN2022115296 W CN 2022115296W WO 2023116020 A1 WO2023116020 A1 WO 2023116020A1
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negative electrode
electrode material
silicon
present
preparation
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PCT/CN2022/115296
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French (fr)
Chinese (zh)
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余海军
陈江东
谢英豪
徐加雷
吴奔奔
李长东
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广东邦普循环科技有限公司
湖南邦普循环科技有限公司
湖南邦普汽车循环有限公司
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Publication of WO2023116020A1 publication Critical patent/WO2023116020A1/en

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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
    • 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
    • H01M4/5805—Phosphides
    • 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
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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 invention belongs to the technical field of secondary batteries, and in particular relates to a negative electrode material and a preparation method and application thereof.
  • Lithium-ion battery is a secondary battery with the advantages of large capacity, light weight, and long life.
  • Materials that can be used for the negative electrode of lithium-ion batteries include lithium metal (Li), elemental silicon (Si), graphite, silicon carbon, tin selenide ( SnSex ), trimanganese tetraoxide (Mn 3 O 4 ), rhenium disulfide (ReS 2 ) etc.
  • Li lithium metal
  • Si elemental silicon
  • Si graphite
  • silicon carbon silicon
  • SnSex tin selenide
  • Mn 3 O 4 trimanganese tetraoxide
  • ReS 2 rhenium disulfide
  • graphite anode is the most mature anode commercially, which has excellent conductivity and good cycle stability, but its gram specific capacity (372mAh ⁇ g -1 ) is an obstacle to improve the energy density of lithium-ion batteries.
  • lithium metal anodes have the advantages of large theoretical capacity, low density, and
  • Silicon has the advantages of high theoretical capacity (4200mAh ⁇ g -1 ), abundant resources, and low price. It is expected to replace the current graphite anode for large-scale commercialization. However, the large volume change ( ⁇ 300%) of silicon materials during charge and discharge must be overcome before commercialization.
  • the present invention aims to solve at least one of the technical problems in the above-mentioned prior art. For this reason, the present invention proposes a negative electrode material, which can greatly improve the cycle stability of silicon-based negative electrodes through the design of structure and composition.
  • the present invention also proposes a preparation method of the above negative electrode material.
  • the present invention also proposes the application of the above-mentioned negative electrode material.
  • a negative electrode material including: a silicon-based core, a carbon-based layer wrapping the silicon-based core, and a metal phosphide wrapped on the surface of the carbon-based layer;
  • the carbon-based layer has a pore structure.
  • the negative electrode material provided by the present invention has a double-layer core-shell structure, and the outermost shell is a metal phosphide.
  • Li 3 P can be formed during the discharge process, which improves the storage capacity of Li+, that is, further improves The discharge capacity of the negative electrode material; at the same time, metal phosphide also has excellent electrical conductivity, so it can improve the rate performance of the negative electrode material;
  • the middle layer is a carbon-based layer, which can improve the electronic conductivity of the negative electrode material and improve its rate performance;
  • the core is silicon-based particles, which can take advantage of its unique high capacity density
  • the present invention can obtain negative electrode materials with high capacity and high electronic conductivity through structural design and synergy among components.
  • the present invention sets a carbon base layer with a pore structure between the outermost metal phosphide and the silicon-based core, wherein the pore structure can increase the specific surface area of the negative electrode material on the one hand, improve the ability to accommodate Li+, and provide it with a transmission channel , increase the diffusion rate of Li+, and further improve the rate performance of the above-mentioned negative electrode materials;
  • the carbon in the base layer and the silicon in the silicon base layer can form a Si-C strong chemical bond, promote the transfer of electrons, enhance the interaction between the silicon-based core and the carbon base layer, and avoid damage to the negative electrode material during cycling;
  • the present invention adopts carbon base layer and metal phosphide to double-layer wrap the silicon-based core, on the one hand, it can effectively suppress the damage caused by the volume expansion of the silicon-based core, on the other hand, even if part of the silicon-based material is damaged, it will not affect other negative electrode materials, It will not affect the normal work of other components such as electrolyte.
  • the present invention can significantly improve the cycle stability and rate performance of the anode material through structural design.
  • the negative electrode material of the present invention there is a synergy between the components and the structure, so after 800 cycles of the obtained negative electrode material with a current density of 4A/g, the reversible capacity is still as high as 1287.18mAh/g, and the capacity retention rate is ⁇ 71.8 %, with extremely high capacity density and cycle stability.
  • the metal phosphide includes at least one of iron phosphide, nickel phosphide, molybdenum phosphide and cobalt phosphide.
  • the electronic conductivity of the iron phosphide, nickel phosphide, molybdenum phosphide and cobalt phosphide are all excellent.
  • the particle size of the negative electrode material is 1-3 ⁇ m.
  • the specific surface area of the negative electrode material is 300-400 m 2 /g.
  • the carbon-based layer has a thickness of 0.4-0.8 ⁇ m.
  • gaps exist between the carbon-based layer and the metal phosphide.
  • the silicon-based core includes 200-500 nm nano-silicon.
  • the invention adopts the nano-scale silicon-based inner core, which can reduce the diffusion distance of Li+, improve the electronic conductivity, and alleviate the volume change in the charging and discharging process.
  • the carbon-based layer is doped with at least one of phosphorus and nitrogen.
  • Nitrogen and phosphorus can form Si-N bonds with the silicon-based core to enhance the force between the carbon-based layer and the silicon-based core;
  • Nitrogen doping promotes the transfer of electrons, and phosphorus is doped in the silicon-carbon material as an electron donor. After the combination of the two, the electronic structure in the silicon-carbon material can be adjusted, thereby improving its electronic conductivity.
  • a method for preparing the negative electrode material comprising the steps of:
  • the ligands include phosphorus-containing ligands
  • reaction mechanism of described preparation method is as follows:
  • step S1 a solvothermal method is used to in-situ synthesize a layer of phosphorus-containing MOF material on the surface of silicon-based particles;
  • step S2 the solid obtained in step S1 is calcined.
  • the MOF material is used as a template to form a carbon-based layer with a pore structure; the metal ions and phosphorus in the MOF material form a metal phosphide during the calcination process, and the metal phosphide tends to concentrate on the surface of the carbon-based layer, forming the outermost shell of the negative electrode material.
  • the present invention innovatively proposes and implements the use of phosphorus in MOF materials as a phosphorus source for the synthesis of metal phosphides, so there is no need to add phosphorus sources again in the subsequent preparation process, which not only saves the process, but also avoids additional additions
  • the problem of uneven distribution caused by the phosphorus source the uniformity of the distribution of the metal phosphide on the surface of the negative electrode material is improved.
  • the present invention adopts MOF material as the precursor of the carbon base layer.
  • the MOF material has a large specific surface area, porous structure and inherent carbon skeleton.
  • the carbon base layer generated by carbonization will inherit the advantages of the MOF material and improve the negative electrode material. electrochemical performance;
  • the MOF material will shrink to a certain extent during the calcination process, in the obtained negative electrode material, a certain gap will be generated between the metal phosphide and the carbon-based layer, that is, a hollow structure, which further increases the strength of the obtained negative electrode material.
  • the specific surface area can effectively alleviate the volume change during charging and discharging, fully expose the active sites and shorten the ion diffusion distance.
  • the preparation method of the present invention combines the advantages of MOF materials, silicon-based particles and metal phosphides, while avoiding their respective original shortcomings, and obtains negative electrode materials with excellent comprehensive performance.
  • the preparation method provided by the invention has simple operation, mild reaction conditions, no pollution to the environment, and is suitable for industrial production.
  • the silicon-based particles are nano-silicon. In some embodiments of the present invention, in step S1, the particle diameter of the silicon-based particles is 200-500 nm.
  • step S1 the silicon-based particles are added in an amount of 1-2 g.
  • step S1 the molar ratio of the metal salt to the silicon-based particles is about 1:(3-6).
  • the metal salt includes at least one of nickel salt, cobalt salt, molybdenum salt and iron salt.
  • the anion of the metal salt includes at least one of chloride ion, sulfate ion and nitrate ion.
  • the phosphorus-containing ligand includes at least one of hydroxyethylidene diphosphonic acid and glyphosate.
  • the ligands further include nitrogen-containing ligands.
  • the nitrogen-containing ligand includes at least one of pyrazine, bipyridine (bpy) and phenanthroline (Phen).
  • step S1 the molar ratio of the metal salt to the phosphorus-containing ligand is 1: (1-2).
  • the molar ratio of the metal salt, phosphorus-containing ligand and nitrogen-containing ligand is 1:(1-2):(1-2).
  • step S1 the molar ratio of the metal salt to the ligand is 1:(1-4).
  • step S1 the molar ratio of the metal salt to the ligand is 1:(2-4).
  • the solvent used in the solvothermal reaction includes at least one of N,N-dimethylformamide (DMF), methanol and ethanol.
  • step S1 in the solvothermal reaction, the ratio of the volume of the solvent to the mass of the silicon-based particles is 2-3 mL:0.1 g.
  • step S1 the temperature of the solvothermal reaction is 100-150°C.
  • step S1 the duration of the solvothermal reaction is 10-16 hours.
  • step S1 further includes dispersing the silicon-based particles, metal salt and ligand in the solvent before the solvothermal reaction.
  • the dispersing includes stirring the metal salt and the ligand and the solvent first, and then adding the silicon-based particles and ultrasonicating.
  • the duration of the stirring is 30-60 minutes.
  • the power of the ultrasound is 60-90%.
  • the 100% power of the ultrasound is 150W.
  • the duration of the ultrasound is 30-60 minutes.
  • step S1 further includes washing and drying the obtained solid after the solid-liquid separation.
  • the cleaning includes sequentially washing with water and 30-99.5 wt% ethanol solution.
  • solid-liquid separation is required after the washing.
  • step S1 centrifugation may be used for all solid-liquid separation steps.
  • the rotational speed of the centrifugation method is 8000-10000 rpm.
  • the drying temperature is 50-70°C.
  • the drying temperature is about 60°C.
  • the drying time is 10-18 hours.
  • the drying time is about 12 hours.
  • the drying method is vacuum drying.
  • the protective atmosphere includes at least one of nitrogen and inert gas.
  • step S2 the constant temperature of the calcination is 450-550°C.
  • step S2 the constant temperature of the calcination is 4-6 hours.
  • step S2 the heating rate of the calcination is 2-7° C./min.
  • step S2 also includes washing after the calcination.
  • the washing after calcination includes at least one of washing with water and washing with ethanol.
  • a negative electrode is proposed, and the raw material for preparation includes the negative electrode material or the negative electrode material obtained by the preparation method.
  • the invention synthesizes a metal phosphide-coated silicon carbon core-shell negative electrode material through a simple method, introduces highly stable N and C sources, and forms a high-performance composite negative electrode material.
  • the volume expansion can be effectively suppressed, thereby improving the battery life of the silicon anode for lithium-ion batteries, while having high capacity and high rate performance.
  • the preparation method of the negative electrode includes the following steps:
  • step D2 mixing and homogenizing the mixture obtained in step D1 with the diluent;
  • step D2 Coating the slurry obtained in step D2 on the current collector, drying and rolling.
  • the conductive agent in step D1, includes at least one of acetylene black and graphene.
  • the binder in step D1, includes at least one of styrene-butadiene rubber (SBR), sodium carboxymethylcellulose (CMC) and polyvinylidene fluoride (PVDF).
  • SBR styrene-butadiene rubber
  • CMC sodium carboxymethylcellulose
  • PVDF polyvinylidene fluoride
  • the binder in step D1, is a mixture of styrene-butadiene rubber (SBR) and sodium carboxymethylcellulose (CMC).
  • SBR styrene-butadiene rubber
  • CMC sodium carboxymethylcellulose
  • step D1 the mixing method is dry mixing and stirring.
  • the silicon carbon material accounts for 70-80%; the conductive agent accounts for 10-20%; the binder accounts for 10-20% ;
  • the binder includes 5-10% of CMC and 5-10% of SBR.
  • the diluent in step D2, includes water or N,N-dimethyldiamide.
  • step D2 the solid content of the slurry is 40-60 wt%.
  • step D2 the viscosity of the slurry is 4500-6000 cps.
  • the current collector includes copper foil.
  • a secondary battery including the negative electrode.
  • Fig. 1 is the schematic flow chart of embodiment 1 of the present invention.
  • Fig. 2 is the cycle performance of the battery obtained by the application example of the present invention.
  • Fig. 3 is the adsorption-desorption isotherm of embodiment 1 gained negative electrode material
  • Example 4 is a SEM image of the negative electrode material obtained in Example 1.
  • the operating temperature in the specific examples is about 25°C;
  • Metal salts, hydroxyethylidene diphosphonic acid and pyrazine were purchased from Shanghai McLean Biochemical Technology Co., Ltd.;
  • Nano-silicon was purchased from Guangdong Bangpu Cycle Technology Co., Ltd., and the particle size was dispersed between 200-500nm;
  • DMF and hydrochloric acid were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.
  • a negative electrode material is prepared, and the specific process is as follows:
  • step S1b Add 1 g of nano-silicon to the mixture obtained in step S1a, set the ultrasonic power to 90%, and ultrasonically disperse for 30 minutes;
  • step S1c Move the mixture obtained in step S1b into a reactor, and react at 100° C. for 15 hours;
  • step S1d Cool the mixture obtained in step S1c, centrifuge at a rotational speed of 8000 rpm, wash the obtained solid with distilled water and ethanol solution, and dry at 70° C. for 10 h to obtain a precursor;
  • step S2 Use a tube furnace to heat the precursor obtained in step S1 to 550°C for 4 hours at a constant temperature and calcinate it at a constant temperature of 7°C/min. After cooling with the furnace, wash the obtained product with distilled water until it is neutral. Filter and dry the solid at 70°C for 6h.
  • FIG. 1 The flow diagram of this embodiment is shown in FIG. 1 .
  • a negative electrode material is prepared, and the specific process is as follows:
  • step S1b Add 1.5 g of nano-silicon to the mixture obtained in step S1a, set the ultrasonic power to 70%, and ultrasonically disperse for 60 minutes;
  • step S1c Move the mixture obtained in step S1b into a reactor, and react at 150° C. for 10 h;
  • step S1d Cool the mixture obtained in step S1c, and centrifuge at 10000 rpm, wash the obtained solid with distilled water and ethanol solution several times, and dry at 60° C. for 12 hours to obtain a precursor;
  • step S2 Use a tube furnace to heat the precursor obtained in step S1 to 450°C for 6 hours at a constant temperature in an N 2 atmosphere. The heating rate is 2°C/min. After cooling with the furnace, the obtained product is washed with distilled water until it is neutral, filtered, and solidified. Dry at 70°C for 6h.
  • a negative electrode material is prepared, and the specific process is as follows:
  • step S1b Add 1 g of nano-silicon to the mixture obtained in step S1a, set the ultrasonic power to 90%, and ultrasonically disperse for 30 minutes;
  • step S1c Move the mixture obtained in step S1b into a reactor, and react at 100° C. for 15 hours;
  • step S1d Cool the mixture obtained in step S1c, centrifuge at a rotation speed of 8000 rpm, wash the obtained solid with distilled water and ethanol solution several times, and dry at 70°C for 10 hours to obtain a precursor;
  • step S2 Use a tube furnace to heat the precursor obtained in step S1 to 550°C for 4 hours at a constant temperature of 550°C for 4 hours in an atmosphere of N 2 . Cool with the furnace, wash the resulting product with distilled water until it is neutral, and filter it. Dry at 70°C for 6h.
  • a negative electrode material is prepared, and the specific process is as follows:
  • step S1b Add 1.5 g of nano-silicon to the mixture obtained in step S1a, set the ultrasonic power to 70%, and ultrasonically disperse for 60 minutes;
  • step S1c Move the mixture obtained in step S1b into a reactor, and react at 150° C. for 10 h;
  • step S1d Cool the mixture obtained in step S1c, centrifuge at a rotational speed of 10,000 rpm, wash the obtained solid with distilled water and ethanol solution several times, and dry at 60° C. for 12 hours to obtain a precursor;
  • step S2 Use a tube furnace to heat the precursor obtained in step S1 to 450°C for 6 hours at a constant temperature under N2 atmosphere. The heating rate is 2°C/min. Cool with the furnace, wash the obtained product with distilled water until it is neutral, and filter it. Dry at 70°C for 6h.
  • a negative electrode material is prepared, and the specific process is as follows:
  • step S1b Add 1 g of nano-silicon to the mixture obtained in step S1a, set the ultrasonic power to 90%, and ultrasonically disperse for 30 minutes;
  • step S1c Move the mixture obtained in step S1b into a reactor, and react at 100° C. for 15 hours;
  • step S1d Cool the mixture obtained in step S1c, centrifuge at a rotational speed of 8000 rpm, wash the obtained solid with distilled water and ethanol solution several times, and dry at 70° C. for 10 hours to obtain a precursor;
  • step S2 Use a tube furnace to heat the precursor obtained in step S1 to 550°C for 4 hours at a constant temperature under N2 atmosphere, and calcine at a constant temperature of 7°C/min. Cool with the furnace, wash the obtained product with distilled water until it is neutral, filter, and The solid was dried at 70°C for 6h.
  • a negative electrode material is prepared, and the specific process is as follows:
  • step S1b Add 1.5 g of nano-silicon to the mixture obtained in step S1a, set the ultrasonic power to 70%, and ultrasonically disperse for 60 minutes;
  • step S1c Move the mixture obtained in step S1b into a reactor, and react at 150° C. for 10 h;
  • step S1d Cool the mixture obtained in step S1c, centrifuge at a rotational speed of 10,000 rpm, wash the obtained solid with distilled water and ethanol solution several times, and dry at 60° C. for 12 hours to obtain a precursor;
  • step S2 Use a tube furnace to heat the precursor obtained in step S1 to 450°C for 6 hours at a constant temperature under N 2 atmosphere. The heating rate is 2°C/min. After cooling with the furnace, wash the obtained product with distilled water until neutral, and filter , Dry the solid at 70°C for 6h.
  • This comparative example has prepared a kind of negative electrode material, and the difference with embodiment 4 is:
  • the ligand in step S1a does not include hydroxyethylidene diphosphonic acid, but only includes 0.02mol of pyrazine;
  • step S1a The metal salt in step S1a is ferrous chloride, not nickel chloride.
  • the nano-silicon used in Examples 1-6 and the obtained negative electrode material were respectively used as the negative electrode active material to prepare the negative electrode sheet.
  • the specific method is as follows:
  • step D2 Dispersing the mixture obtained in step D1 into water to form a slurry with a solid content of 50wt% and a viscosity of 4500-6000cps;
  • step D3 Coat the slurry obtained in step D2 on the current collector, dry it, and roll it to obtain a coating thickness of 90-140 ⁇ m (thickness at different positions fluctuates within the above range), and a compacted density of 1.70-1.90 g/cm 3 (The compaction at different positions fluctuates within the above range).
  • test battery is a button battery formed by the negative electrode obtained in the application example and a lithium sheet
  • test voltage is 0.02-1.2V
  • test current is 4A/g
  • test results are shown in Figure 2.
  • Example 1 the physical and chemical properties of the negative electrode material obtained in Example 1 were also tested, specifically the specific surface area and microscopic morphology of the negative electrode material.
  • Figure 3 is the adsorption-desorption isotherm of the negative electrode material obtained in Example 1.
  • the test method is as follows: the powder sample to be tested is placed in a U-shaped sample tube, and the mixed gas containing a certain proportion of adsorbate flows through the sample. The gas concentration change is used to determine the adsorption amount (BET) of the sample to be tested for the adsorbate molecule (N 2 ).
  • BET adsorption amount
  • the results in Figure 3 show that the sample has a typical H3 hysteresis loop, indicating that it is a mesoporous material, and has a high adsorption and desorption capacity when P/P0 ⁇ 0.02, indicating that it has a more microporous structure, that is
  • the material is a porous material which is mainly microporous and mesoporous.
  • the specific surface area of the negative electrode material obtained in the present invention is 300-400 m 2 /g.
  • the negative electrode material obtained by the invention is spherical, and the main particle size distribution is between 1 and 3 ⁇ m.
  • the specific morphology is shown in Figure 4.
  • the outer layer of each sphere is brighter. According to the mass-thickness contrast, the sphere (negative electrode material) has a core-shell structure, but the outermost shell structure is very thin.

Abstract

Disclosed in the present invention are a negative electrode material, a preparation method therefor, and an application thereof. The negative electrode material comprises a silicon-based core, a carbon-based layer wrapped on the surface of the silicon-based core, and a metal phosphide wrapped on the surface of the carbon-based layer, wherein the carbon-based layer has a pore structure. The negative electrode material of the present invention can greatly improve the cycling stability of a silicon-based negative electrode by means of the design of the structure and the components. The present invention also provides a preparation method for and an application of the described negative electrode material.

Description

一种负极材料及其制备方法和应用A kind of negative electrode material and its preparation method and application 技术领域technical field
本发明属于二次电池技术领域，具体涉及一种负极材料及其制备方法和应用。The invention belongs to the technical field of secondary batteries, and in particular relates to a negative electrode material and a preparation method and application thereof.
背景技术Background technique
锂离子电池(Lithium-ion battery，LIB)，是一种二次电池，具有容量大、重量轻、寿命长等优点。可用于锂离子电池负极的材料包括锂金属(Li)、单质硅(Si)、石墨、硅碳、硒化锡(SnSe x)、四氧化三锰(Mn 3O 4)、二硫化铼(ReS 2)等。目前，石墨负极是商业上最成熟的负极，具有优良的导电性和良好的循环稳定性，但其克比容量较低(372mAh·g -1)，是提升锂离子电池能量密度的障碍。此外，锂金属负极虽然具有理论容量大、密度低、氧化还原电位低等优点，但是其面临的锂枝晶问题较其他种类负极更为严重，而锂枝晶可能会造成严重的安全问题。 Lithium-ion battery (LIB) is a secondary battery with the advantages of large capacity, light weight, and long life. Materials that can be used for the negative electrode of lithium-ion batteries include lithium metal (Li), elemental silicon (Si), graphite, silicon carbon, tin selenide ( SnSex ), trimanganese tetraoxide (Mn 3 O 4 ), rhenium disulfide (ReS 2 ) etc. At present, graphite anode is the most mature anode commercially, which has excellent conductivity and good cycle stability, but its gram specific capacity (372mAh·g -1 ) is an obstacle to improve the energy density of lithium-ion batteries. In addition, although lithium metal anodes have the advantages of large theoretical capacity, low density, and low redox potential, the problem of lithium dendrites is more serious than other types of anodes, and lithium dendrites may cause serious safety problems.
硅具有理论容量高(4200mAh·g -1)、资源丰富、价格低廉等优点，有望取代现在的石墨负极进行大规模商业化。然而，在进行商业化之前，必须克服硅材料在充放电过程中体积变化大的问题(～300％)。 Silicon has the advantages of high theoretical capacity (4200mAh·g -1 ), abundant resources, and low price. It is expected to replace the current graphite anode for large-scale commercialization. However, the large volume change (~300%) of silicon materials during charge and discharge must be overcome before commercialization.
为了解决关于硅负极的问题，研究者进行了如下几个方向的探索：其一，将硅基材料进行纳米化，如此可缓解体积膨胀对电池性能的影响；其二，将硅与其他材料进行复合，例如硅碳材料。In order to solve the problem about the silicon anode, researchers have explored the following directions: first, nanometerizing silicon-based materials, which can alleviate the impact of volume expansion on battery performance; second, combining silicon with other materials Composite, such as silicon carbon materials.
但是上述改性思路取得的效果有限，所得硅基负极的循环稳定性仍有待提升。However, the effect of the above modification ideas is limited, and the cycle stability of the obtained silicon-based anode still needs to be improved.
发明内容Contents of the invention
本发明旨在至少解决上述现有技术中存在的技术问题之一。为此，本发明提出一种负极材料，通过结构和成分的设计，能够大幅提升硅基负极的循环稳定性。The present invention aims to solve at least one of the technical problems in the above-mentioned prior art. For this reason, the present invention proposes a negative electrode material, which can greatly improve the cycle stability of silicon-based negative electrodes through the design of structure and composition.
本发明还提出一种上述负极材料的制备方法。The present invention also proposes a preparation method of the above negative electrode material.
本发明还提出上述负极材料的应用。The present invention also proposes the application of the above-mentioned negative electrode material.
根据本发明的一个方面，提出了一种负极材料，包括：硅基内核、包裹所述硅基内核的碳基层，以及包裹于所述碳基层表面的金属磷化物；According to one aspect of the present invention, a negative electrode material is proposed, including: a silicon-based core, a carbon-based layer wrapping the silicon-based core, and a metal phosphide wrapped on the surface of the carbon-based layer;
所述碳基层上具有孔结构。The carbon-based layer has a pore structure.
根据本发明的一种优选的实施方式，至少具有以下有益效果：According to a preferred embodiment of the present invention, it has at least the following beneficial effects:
(1)本发明提供的负极材料具有双层核壳结构，最外层的壳为金属磷化物，通过转化反应，在放电过程中可以形成Li 3P，提升对Li+的存储能力，即进一步提升负极材料的放电容 量；同时金属磷化物还具有优异的导电性能，因此可提升负极材料的倍率性能； (1) The negative electrode material provided by the present invention has a double-layer core-shell structure, and the outermost shell is a metal phosphide. Through the conversion reaction, Li 3 P can be formed during the discharge process, which improves the storage capacity of Li+, that is, further improves The discharge capacity of the negative electrode material; at the same time, metal phosphide also has excellent electrical conductivity, so it can improve the rate performance of the negative electrode material;
中间层为碳基层，可以提升负极材料的电子电导率，提升其倍率性能；The middle layer is a carbon-based layer, which can improve the electronic conductivity of the negative electrode material and improve its rate performance;
内核为硅基颗粒，可发挥其特有的高容量密度的优势；The core is silicon-based particles, which can take advantage of its unique high capacity density;
因此，本发明通过结构设计和成分间的协同作用，可获得具有高容量、高电子电导率的负极材料。Therefore, the present invention can obtain negative electrode materials with high capacity and high electronic conductivity through structural design and synergy among components.
(2)本发明在最外层金属磷化物和硅基内核中间设置了具有孔结构的碳基层，其中孔结构一方面可以提升负极材料的比表面积，提升容纳Li+的能力，为其提供传输通道，提升Li+的扩散速度，进一步提升上述负极材料的倍率性能；另一方面，具有孔结构的碳基层，具有一定的形变能力，可以容纳硅基内核在充放电过程中的体积变化；此外，碳基层中的碳和硅基层中的硅可以形成Si-C强化学键，促进电子的转移，增强硅基内核与碳基层之间的相互作用力，避免负极材料在循环过程中破损；(2) The present invention sets a carbon base layer with a pore structure between the outermost metal phosphide and the silicon-based core, wherein the pore structure can increase the specific surface area of the negative electrode material on the one hand, improve the ability to accommodate Li+, and provide it with a transmission channel , increase the diffusion rate of Li+, and further improve the rate performance of the above-mentioned negative electrode materials; The carbon in the base layer and the silicon in the silicon base layer can form a Si-C strong chemical bond, promote the transfer of electrons, enhance the interaction between the silicon-based core and the carbon base layer, and avoid damage to the negative electrode material during cycling;
本发明采用碳基层和金属磷化物双层包裹硅基内核，一方面可以有效抑制硅基内核体积膨胀带来的破损，另一方面，即便部分硅基材料破损，也不至于影响其他负极材料，更不至于影响电解液等其他部件的正常工作。The present invention adopts carbon base layer and metal phosphide to double-layer wrap the silicon-based core, on the one hand, it can effectively suppress the damage caused by the volume expansion of the silicon-based core, on the other hand, even if part of the silicon-based material is damaged, it will not affect other negative electrode materials, It will not affect the normal work of other components such as electrolyte.
综上，本发明通过结构设计，可显著提升负极材料的循环稳定性和倍率性能。In summary, the present invention can significantly improve the cycle stability and rate performance of the anode material through structural design.
(3)本发明的负极材料中，成分和结构之间发生了协同作用，因此所得负极材料以4A/g的电流密度循环800周后，可逆容量仍高达1287.18mAh/g，容量保持率≥71.8％，具有极高的容量密度和循环稳定性。(3) In the negative electrode material of the present invention, there is a synergy between the components and the structure, so after 800 cycles of the obtained negative electrode material with a current density of 4A/g, the reversible capacity is still as high as 1287.18mAh/g, and the capacity retention rate is ≥71.8 %, with extremely high capacity density and cycle stability.
在本发明的一些实施方式中，所述金属磷化物包括磷化铁、磷化镍、磷化钼和磷化钴中的至少一种。In some embodiments of the present invention, the metal phosphide includes at least one of iron phosphide, nickel phosphide, molybdenum phosphide and cobalt phosphide.
所述磷化铁、磷化镍、磷化钼和磷化钴的电子电导率均非常优异。The electronic conductivity of the iron phosphide, nickel phosphide, molybdenum phosphide and cobalt phosphide are all excellent.
在本发明的一些实施方式中，所述负极材料的粒径为1～3μm。In some embodiments of the present invention, the particle size of the negative electrode material is 1-3 μm.
在本发明的一些实施方式中，所述负极材料的比表面积为300～400m 2/g。 In some embodiments of the present invention, the specific surface area of the negative electrode material is 300-400 m 2 /g.
在本发明的一些实施方式中，所述碳基层的厚度为0.4～0.8μm。In some embodiments of the present invention, the carbon-based layer has a thickness of 0.4-0.8 μm.
在本发明的一些实施方式中，所述碳基层和所述金属磷化物间存在空隙。In some embodiments of the present invention, gaps exist between the carbon-based layer and the metal phosphide.
在本发明的一些实施方式中，所述硅基内核包括200～500nm纳米硅。In some embodiments of the present invention, the silicon-based core includes 200-500 nm nano-silicon.
本发明采用纳米级硅基内核，可减小Li+的扩散距离，提高电子导电性，也可以缓解充放电过程中的体积变化。The invention adopts the nano-scale silicon-based inner core, which can reduce the diffusion distance of Li+, improve the electronic conductivity, and alleviate the volume change in the charging and discharging process.
在本发明的一些实施方式中，所述碳基层中掺杂有磷和氮中的至少一种。In some embodiments of the present invention, the carbon-based layer is doped with at least one of phosphorus and nitrogen.
氮和磷可以与硅基内核形成Si-N键，提升碳基层和硅基内核之间的作用力；Nitrogen and phosphorus can form Si-N bonds with the silicon-based core to enhance the force between the carbon-based layer and the silicon-based core;
氮掺杂促进了电子的转移，磷作为电子给体掺杂在硅碳材料中，两者结合后，可调节硅 碳材料中的电子结构，进而提升其电子导电性。Nitrogen doping promotes the transfer of electrons, and phosphorus is doped in the silicon-carbon material as an electron donor. After the combination of the two, the electronic structure in the silicon-carbon material can be adjusted, thereby improving its electronic conductivity.
根据本发明的再一个方面，提出了所述负极材料的制备方法，包括如下步骤：According to another aspect of the present invention, a method for preparing the negative electrode material is proposed, comprising the steps of:
S1.将硅基颗粒、金属盐和配体进行溶剂热反应后固液分离，得MOF包裹的硅基颗粒；S1. Solvothermal reaction of silicon-based particles, metal salts and ligands followed by solid-liquid separation to obtain MOF-wrapped silicon-based particles;
所述配体包括含磷配体；The ligands include phosphorus-containing ligands;
S2.将所述MOF包裹的硅基颗粒在保护气氛中煅烧。S2. Calcining the MOF-wrapped silicon-based particles in a protective atmosphere.
所述制备方法的反应机理如下：The reaction mechanism of described preparation method is as follows:
步骤S1中，采用溶剂热法，在硅基颗粒表面原位合成一层含磷的MOF材料；In step S1, a solvothermal method is used to in-situ synthesize a layer of phosphorus-containing MOF material on the surface of silicon-based particles;
步骤S2中，煅烧步骤S1所得固体，过程中以MOF材料为模板，形成了具有孔结构的碳基层；MOF材料中的金属离子和磷在煅烧过程中则形成了金属磷化物，并且金属磷化物倾向于富集在碳基层的表面，形成了所述负极材料的最外层壳。In step S2, the solid obtained in step S1 is calcined. During the process, the MOF material is used as a template to form a carbon-based layer with a pore structure; the metal ions and phosphorus in the MOF material form a metal phosphide during the calcination process, and the metal phosphide tends to concentrate on the surface of the carbon-based layer, forming the outermost shell of the negative electrode material.
根据本发明的一种优选的实施方式的制备方法，至少具有以下有益效果：The preparation method according to a preferred embodiment of the present invention has at least the following beneficial effects:
(1)本发明创新性的提出并实现了采用MOF材料中的磷，作为合成金属磷化物的磷源，因此在后续制备过程中无需再次添加磷源，既节约了流程，又避免了额外添加磷源带来的分布不均问题；提升了金属磷化物在所述负极材料表面分布的均匀性。(1) The present invention innovatively proposes and implements the use of phosphorus in MOF materials as a phosphorus source for the synthesis of metal phosphides, so there is no need to add phosphorus sources again in the subsequent preparation process, which not only saves the process, but also avoids additional additions The problem of uneven distribution caused by the phosphorus source; the uniformity of the distribution of the metal phosphide on the surface of the negative electrode material is improved.
(2)本发明采用MOF材料作为碳基层的前驱体，MOF材料具有较大的比表面积、多孔结构和固有的碳骨架，其碳化生成的碳基层会继承MOF材料的优点，提升所述负极材料的电化学性能；(2) The present invention adopts MOF material as the precursor of the carbon base layer. The MOF material has a large specific surface area, porous structure and inherent carbon skeleton. The carbon base layer generated by carbonization will inherit the advantages of the MOF material and improve the negative electrode material. electrochemical performance;
此外，由于MOF材料在煅烧过程中会有一定程度的收缩，因此所得的负极材料中，所述金属磷化物和碳基层之间会产生一定的空隙，即中空结构，这进一步增加了所得负极材料的比表面积，有效缓解充放电过程中的体积变化、充分暴露活性位点以及缩短离子扩散距离。In addition, since the MOF material will shrink to a certain extent during the calcination process, in the obtained negative electrode material, a certain gap will be generated between the metal phosphide and the carbon-based layer, that is, a hollow structure, which further increases the strength of the obtained negative electrode material. The specific surface area can effectively alleviate the volume change during charging and discharging, fully expose the active sites and shorten the ion diffusion distance.
(3)本发明的制备方法将MOF材料、硅基颗粒和金属磷化物的优点融合，同时避免了其各自原有的缺点，获取了综合性能优异的负极材料。(3) The preparation method of the present invention combines the advantages of MOF materials, silicon-based particles and metal phosphides, while avoiding their respective original shortcomings, and obtains negative electrode materials with excellent comprehensive performance.
(4)本发明提供的制备方法操作简单，反应条件温和，对环境无污染，适用于工业化生产。(4) The preparation method provided by the invention has simple operation, mild reaction conditions, no pollution to the environment, and is suitable for industrial production.
在本发明的一些实施方式中，步骤S1中，所述硅基颗粒为纳米硅。在本发明的一些实施方式中，步骤S1中，所述硅基颗粒的粒径为200～500nm。In some embodiments of the present invention, in step S1, the silicon-based particles are nano-silicon. In some embodiments of the present invention, in step S1, the particle diameter of the silicon-based particles is 200-500 nm.
在本发明的一些实施方式中，步骤S1中，所述硅基颗粒的添加量为1～2g。In some embodiments of the present invention, in step S1, the silicon-based particles are added in an amount of 1-2 g.
在本发明的一些实施方式中，步骤S1中，所述金属盐和硅基颗粒的摩尔比约为1:(3～6)。In some embodiments of the present invention, in step S1, the molar ratio of the metal salt to the silicon-based particles is about 1:(3-6).
在本发明的一些实施方式中，步骤S1中，所述金属盐包括镍盐、钴盐、钼盐和铁盐中的至少一种。In some embodiments of the present invention, in step S1, the metal salt includes at least one of nickel salt, cobalt salt, molybdenum salt and iron salt.
在本发明的一些实施方式中，步骤S1中，所述金属盐的阴离子包括氯离子、硫酸根离子 和硝酸根离子中的至少一种。In some embodiments of the present invention, in step S1, the anion of the metal salt includes at least one of chloride ion, sulfate ion and nitrate ion.
在本发明的一些实施方式中，步骤S1中，所述含磷配体包括羟基乙叉二膦酸和草甘二膦中的至少一种。In some embodiments of the present invention, in step S1, the phosphorus-containing ligand includes at least one of hydroxyethylidene diphosphonic acid and glyphosate.
在本发明的一些实施方式中，步骤S1中，所述配体还包括含氮配体。In some embodiments of the present invention, in step S1, the ligands further include nitrogen-containing ligands.
在本发明的一些优选的实施方式中，所述含氮配体包括吡嗪、联吡啶(bpy)和邻啡啰啉(Phen)中的至少一种。In some preferred embodiments of the present invention, the nitrogen-containing ligand includes at least one of pyrazine, bipyridine (bpy) and phenanthroline (Phen).
在本发明的一些实施方式中，步骤S1中，所述金属盐和含磷配体的摩尔比为1：(1～2)。In some embodiments of the present invention, in step S1, the molar ratio of the metal salt to the phosphorus-containing ligand is 1: (1-2).
在本发明的一些实施方式中，所述金属盐、含磷配体和含氮配体的摩尔比为1：(1～2)：(1～2)。In some embodiments of the present invention, the molar ratio of the metal salt, phosphorus-containing ligand and nitrogen-containing ligand is 1:(1-2):(1-2).
在本发明的一些实施方式中，步骤S1中，所述金属盐和配体的摩尔比为1：(1～4)。In some embodiments of the present invention, in step S1, the molar ratio of the metal salt to the ligand is 1:(1-4).
在本发明的一些优选的实施方式中，步骤S1中，所述金属盐和配体的摩尔比为1：(2～4)。In some preferred embodiments of the present invention, in step S1, the molar ratio of the metal salt to the ligand is 1:(2-4).
在本发明的一些实施方式中，步骤S1中，所述溶剂热反应采用的溶剂包括N,N-二甲基甲酰胺(DMF)、甲醇和乙醇中的至少一种。In some embodiments of the present invention, in step S1, the solvent used in the solvothermal reaction includes at least one of N,N-dimethylformamide (DMF), methanol and ethanol.
在本发明的一些实施方式中，步骤S1中，所述溶剂热反应中，溶剂的体积与所述硅基颗粒的质量之比为2～3mL：0.1g。In some embodiments of the present invention, in step S1, in the solvothermal reaction, the ratio of the volume of the solvent to the mass of the silicon-based particles is 2-3 mL:0.1 g.
在本发明的一些实施方式中，步骤S1中，所述溶剂热反应的温度为100～150℃。In some embodiments of the present invention, in step S1, the temperature of the solvothermal reaction is 100-150°C.
在本发明的一些实施方式中，步骤S1中，所述溶剂热反应的时长为10～16h。In some embodiments of the present invention, in step S1, the duration of the solvothermal reaction is 10-16 hours.
在本发明的一些实施方式中，步骤S1中，在所述溶剂热反应前，还包括将所述硅基颗粒、金属盐和配体分散在所述溶剂中。In some embodiments of the present invention, step S1 further includes dispersing the silicon-based particles, metal salt and ligand in the solvent before the solvothermal reaction.
在本发明的一些实施方式中，所述分散包括先将所述金属盐和配体和所述溶剂进行搅拌，之后添加所述硅基颗粒并进行超声。In some embodiments of the present invention, the dispersing includes stirring the metal salt and the ligand and the solvent first, and then adding the silicon-based particles and ultrasonicating.
在本发明的一些实施方式中，所述搅拌的时长为30～60min。In some embodiments of the present invention, the duration of the stirring is 30-60 minutes.
在本发明的一些实施方式中，所述超声的功率为60～90％。In some embodiments of the present invention, the power of the ultrasound is 60-90%.
在本发明的一些实施方式中，所述超声的100％功率为150W。In some embodiments of the present invention, the 100% power of the ultrasound is 150W.
在本发明的一些实施方式中，所述超声的时长为30～60min。In some embodiments of the present invention, the duration of the ultrasound is 30-60 minutes.
在本发明的一些实施方式中，步骤S1中，还包括在所述固液分离后清洗并干燥所得固体。In some embodiments of the present invention, step S1 further includes washing and drying the obtained solid after the solid-liquid separation.
在本发明的一些实施方式中，所述清洗包括依次采用水和30～99.5wt％的乙醇溶液洗涤。In some embodiments of the present invention, the cleaning includes sequentially washing with water and 30-99.5 wt% ethanol solution.
在本发明的一些实施方式中，所述洗涤后需进行固液分离。In some embodiments of the present invention, solid-liquid separation is required after the washing.
在本发明的一些实施方式中，步骤S1中，所有进行固液分离的步骤，均可选用离心法。In some embodiments of the present invention, in step S1, centrifugation may be used for all solid-liquid separation steps.
在本发明的一些实施方式中，所述离心法的转速为8000～10000rpm。In some embodiments of the present invention, the rotational speed of the centrifugation method is 8000-10000 rpm.
在本发明的一些实施方式中，所述干燥的温度为50～70℃。In some embodiments of the present invention, the drying temperature is 50-70°C.
在本发明的一些优选的实施方式中，所述干燥的温度约为60℃。In some preferred embodiments of the present invention, the drying temperature is about 60°C.
在本发明的一些实施方式中，所述干燥的时长为10～18h。In some embodiments of the present invention, the drying time is 10-18 hours.
在本发明的一些优选的实施方式中，所述干燥的时长约为12h。In some preferred embodiments of the present invention, the drying time is about 12 hours.
在本发明的一些优选的实施方式中，所述干燥的方式为真空干燥。In some preferred embodiments of the present invention, the drying method is vacuum drying.
在本发明的一些实施方式中，步骤S2中，所述保护气氛包括氮气和惰性气体中的至少一种。In some embodiments of the present invention, in step S2, the protective atmosphere includes at least one of nitrogen and inert gas.
在本发明的一些实施方式中，步骤S2中，所述煅烧的恒温温度为450～550℃。In some embodiments of the present invention, in step S2, the constant temperature of the calcination is 450-550°C.
在本发明的一些实施方式中，步骤S2中，所述煅烧的恒温时长为4～6h。In some embodiments of the present invention, in step S2, the constant temperature of the calcination is 4-6 hours.
在本发明的一些实施方式中，步骤S2中，所述煅烧的升温速率为2～7℃/min。In some embodiments of the present invention, in step S2, the heating rate of the calcination is 2-7° C./min.
在本发明的一些实施方式中，步骤S2中，还包括在所述煅烧后进行洗涤。In some embodiments of the present invention, step S2 also includes washing after the calcination.
在本发明的一些实施方式中，所述煅烧后的洗涤包括水洗和乙醇洗中的至少一种。In some embodiments of the present invention, the washing after calcination includes at least one of washing with water and washing with ethanol.
根据本发明的再一个方面，提出了一种负极，制备原料包括所述的负极材料或所述制备方法制得的负极材料。According to still another aspect of the present invention, a negative electrode is proposed, and the raw material for preparation includes the negative electrode material or the negative electrode material obtained by the preparation method.
根据本发明的一种优选的实施方式的负极，至少具有以下有益效果：The negative electrode according to a preferred embodiment of the present invention has at least the following beneficial effects:
本发明通过简易方法合成金属磷化物包覆硅碳的核壳结构的负极材料，引进高稳定性的N、C源，形成高性能复合型负极材料，由其制备的负极在充放电过程中的体积膨胀可被有效抑制，进而提高硅负极用于锂离子电池的续航能力，同时具备高容量和高倍率性能。The invention synthesizes a metal phosphide-coated silicon carbon core-shell negative electrode material through a simple method, introduces highly stable N and C sources, and forms a high-performance composite negative electrode material. The volume expansion can be effectively suppressed, thereby improving the battery life of the silicon anode for lithium-ion batteries, while having high capacity and high rate performance.
在本发明的一些实施方式中，所述负极的制备方法包括如下步骤：In some embodiments of the present invention, the preparation method of the negative electrode includes the following steps:
D1.将导电剂和所述负极材料干混后，与粘结剂进行干混；D1. After dry mixing the conductive agent and the negative electrode material, dry mixing with the binder;
D2.将步骤D1所得混合物和稀释剂混合匀浆；D2. mixing and homogenizing the mixture obtained in step D1 with the diluent;
D3.将步骤D2所得浆料涂覆在集流体上后，干燥、辊压即得。D3. Coating the slurry obtained in step D2 on the current collector, drying and rolling.
在本发明的一些实施方式中，步骤D1中，所述导电剂包括乙炔黑和石墨烯中的至少一种。In some embodiments of the present invention, in step D1, the conductive agent includes at least one of acetylene black and graphene.
在本发明的一些实施方式中，步骤D1中，所述粘结剂包括丁苯橡胶(SBR)、羧甲基纤维素钠(CMC)和聚偏氟乙烯(PVDF)中的至少一种。In some embodiments of the present invention, in step D1, the binder includes at least one of styrene-butadiene rubber (SBR), sodium carboxymethylcellulose (CMC) and polyvinylidene fluoride (PVDF).
在本发明的一些优选的实施方式中，步骤D1中，所述粘结剂为丁苯橡胶(SBR)和羧甲基纤维素钠(CMC)的混合物。In some preferred embodiments of the present invention, in step D1, the binder is a mixture of styrene-butadiene rubber (SBR) and sodium carboxymethylcellulose (CMC).
在本发明的一些实施方式中，步骤D1中，所述混合的方法为干混搅拌。In some embodiments of the present invention, in step D1, the mixing method is dry mixing and stirring.
在本发明的一些实施方式中，按质量百分数计，步骤D1所得混合物中，所述硅碳材料 占70～80％；所述导电剂占10～20％；所述粘结剂10～20％；In some embodiments of the present invention, in terms of mass percentage, in the mixture obtained in step D1, the silicon carbon material accounts for 70-80%; the conductive agent accounts for 10-20%; the binder accounts for 10-20% ;
所述粘结剂包括5～10％的CMC和5～10％的SBR。The binder includes 5-10% of CMC and 5-10% of SBR.
在本发明的一些实施方式中，步骤D2中，所述稀释剂包括水或N,N-二甲基二酰胺。In some embodiments of the present invention, in step D2, the diluent includes water or N,N-dimethyldiamide.
在本发明的一些实施方式中，在本发明的一些实施方式中，步骤D2中，所述浆料的固含量为40～60wt％。In some embodiments of the present invention, in step D2, the solid content of the slurry is 40-60 wt%.
在本发明的一些实施方式中，步骤D2中，所述浆料的粘度为4500～6000cps。In some embodiments of the present invention, in step D2, the viscosity of the slurry is 4500-6000 cps.
在本发明的一些实施方式中，步骤D3中，所述集流体包括铜箔。In some embodiments of the present invention, in step D3, the current collector includes copper foil.
根据本发明的再一个方面，提出了一种二次电池，包括所述的负极。According to still another aspect of the present invention, a secondary battery is provided, including the negative electrode.
若无特殊说明，本发明中的“约”表示允许误差在±2％之间。Unless otherwise specified, "about" in the present invention means that the allowable error is between ±2%.
附图说明Description of drawings
下面结合附图和实施例对本发明做进一步的说明，其中：The present invention will be further described below in conjunction with accompanying drawing and embodiment, wherein:
图1为本发明实施例1的流程示意图；Fig. 1 is the schematic flow chart of embodiment 1 of the present invention;
图2为本发明应用例所得电池的循环性能；Fig. 2 is the cycle performance of the battery obtained by the application example of the present invention;
图3为实施例1所得负极材料的吸附脱附等温线；Fig. 3 is the adsorption-desorption isotherm of embodiment 1 gained negative electrode material;
图4为实施例1所得负极材料的SEM图。4 is a SEM image of the negative electrode material obtained in Example 1.
具体实施方式Detailed ways
以下将结合实施例对本发明的构思及产生的技术效果进行清楚、完整地描述，以充分地理解本发明的目的、特征和效果。显然，所描述的实施例只是本发明的一部分实施例，而不是全部实施例，基于本发明的实施例，本领域的技术人员在不付出创造性劳动的前提下所获得的其他实施例，均属于本发明保护的范围。The conception and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments, so as to fully understand the purpose, features and effects of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts belong to The protection scope of the present invention.
若无特殊说明，具体实施例中操作的温度约为25℃；Unless otherwise specified, the operating temperature in the specific examples is about 25°C;
金属盐、羟基乙叉二膦酸和吡嗪购自上海麦克林生化科技有限公司；Metal salts, hydroxyethylidene diphosphonic acid and pyrazine were purchased from Shanghai McLean Biochemical Technology Co., Ltd.;
纳米硅购自广东邦普循环科技有限公司，粒径分散于200～500nm之间；Nano-silicon was purchased from Guangdong Bangpu Cycle Technology Co., Ltd., and the particle size was dispersed between 200-500nm;
DMF、盐酸购自上海阿拉丁生化科技有限公司。DMF and hydrochloric acid were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.
实施例1Example 1
本实施例制备了一种负极材料，具体过程为：In this embodiment, a negative electrode material is prepared, and the specific process is as follows:
S1.制备前驱体：S1. Preparation of precursor:
S1a.MOF原料混合：将0.01mol硝酸钴、0.01mol羟基乙叉二膦酸(C 2H 8O 7P 2，HEDP)和0.01mol吡嗪(C 4H 4N 2)溶于20mL的N,N-二甲基甲酰胺(DMF)，磁力搅拌30min，使物料溶解完全； S1a. MOF raw material mixing: 0.01mol cobalt nitrate, 0.01mol hydroxyethylidene diphosphonic acid (C 2 H 8 O 7 P 2 , HEDP) and 0.01mol pyrazine (C 4 H 4 N 2 ) were dissolved in 20 mL of N , N-dimethylformamide (DMF), magnetically stirred for 30min to dissolve the material completely;
S1b.向步骤S1a所得混合物中加入1g的纳米硅，设置超声功率为90％，超声分散30min；S1b. Add 1 g of nano-silicon to the mixture obtained in step S1a, set the ultrasonic power to 90%, and ultrasonically disperse for 30 minutes;
S1c.将步骤S1b所得混合物移入反应釜，并于100℃反应15h；S1c. Move the mixture obtained in step S1b into a reactor, and react at 100° C. for 15 hours;
S1d.将步骤S1c所得混合物冷却，在转速8000rpm下离心，用蒸馏水和乙醇溶液洗涤所得固体，并在70℃干燥10h，得到前驱体；S1d. Cool the mixture obtained in step S1c, centrifuge at a rotational speed of 8000 rpm, wash the obtained solid with distilled water and ethanol solution, and dry at 70° C. for 10 h to obtain a precursor;
S2.将步骤S1所得将前驱体用管式炉在N 2氛围下，升温至550℃恒温煅烧4h，升温速率为7℃/min，随炉冷却后，用蒸馏水将所得产物洗至中性，过滤，将固体在70℃干燥6h即得。 S2. Use a tube furnace to heat the precursor obtained in step S1 to 550°C for 4 hours at a constant temperature and calcinate it at a constant temperature of 7°C/min. After cooling with the furnace, wash the obtained product with distilled water until it is neutral. Filter and dry the solid at 70°C for 6h.
本实施例的流程示意图如图1所示。The flow diagram of this embodiment is shown in FIG. 1 .
实施例2Example 2
本实施例制备了一种负极材料，具体过程为：In this embodiment, a negative electrode material is prepared, and the specific process is as follows:
S1.制备前驱体：S1. Preparation of precursor:
S1a.MOF原料混合：将0.01mol硝酸钴、0.02mol羟基乙叉二膦酸(C 2H 8O 7P 2，HEDP)和0.02mol吡嗪(C 4H 4N 2)溶于30mL的N,N-二甲基甲酰胺(DMF)，磁力搅拌60min，使物料溶解完全； S1a. MOF raw material mixing: 0.01mol cobalt nitrate, 0.02mol hydroxyethylidene diphosphonic acid (C 2 H 8 O 7 P 2 , HEDP) and 0.02mol pyrazine (C 4 H 4 N 2 ) were dissolved in 30 mL of N , N-dimethylformamide (DMF), magnetically stirred for 60min to completely dissolve the material;
S1b.向步骤S1a所得混合物中加入1.5g的纳米硅，设置超声功率为70％，超声分散60min；S1b. Add 1.5 g of nano-silicon to the mixture obtained in step S1a, set the ultrasonic power to 70%, and ultrasonically disperse for 60 minutes;
S1c.将步骤S1b所得混合物移入反应釜，150℃反应10h；S1c. Move the mixture obtained in step S1b into a reactor, and react at 150° C. for 10 h;
S1d.将步骤S1c所得混合物冷却，并以10000rpm转速离心，用蒸馏水和乙醇溶液多次洗涤所得固体，并在60℃干燥12h，得到前驱体；S1d. Cool the mixture obtained in step S1c, and centrifuge at 10000 rpm, wash the obtained solid with distilled water and ethanol solution several times, and dry at 60° C. for 12 hours to obtain a precursor;
S2.将步骤S1所得前驱体用管式炉在N 2氛围下升温至450℃恒温煅烧6h，升温速率为2℃/min，随炉冷却后，所得产物用蒸馏水洗至中性，过滤，固体在70℃干燥6h即得。 S2. Use a tube furnace to heat the precursor obtained in step S1 to 450°C for 6 hours at a constant temperature in an N 2 atmosphere. The heating rate is 2°C/min. After cooling with the furnace, the obtained product is washed with distilled water until it is neutral, filtered, and solidified. Dry at 70°C for 6h.
实施例3Example 3
本实施例制备了一种负极材料，具体过程为：In this embodiment, a negative electrode material is prepared, and the specific process is as follows:
S1.制备前驱体：S1. Preparation of precursor:
S1a.MOF原料混合：将0.01mol氯化镍、0.01mol羟基乙叉二膦酸(C 2H 8O 7P 2，HEDP)和0.01mol吡嗪(C 4H 4N 2)溶于20mL的N,N-二甲基甲酰胺(DMF)，磁力搅拌30min，使物料溶解完全； S1a. MOF raw material mixing: 0.01mol nickel chloride, 0.01mol hydroxyethylidene diphosphonic acid (C 2 H 8 O 7 P 2 , HEDP) and 0.01mol pyrazine (C 4 H 4 N 2 ) were dissolved in 20 mL N,N-dimethylformamide (DMF), magnetically stirred for 30min to dissolve the material completely;
S1b.向步骤S1a所得的混合物中加入1g的纳米硅，设置超声功率为90％，超声分散30min；S1b. Add 1 g of nano-silicon to the mixture obtained in step S1a, set the ultrasonic power to 90%, and ultrasonically disperse for 30 minutes;
S1c.将步骤S1b所得混合物移入反应釜，于100℃反应15h；S1c. Move the mixture obtained in step S1b into a reactor, and react at 100° C. for 15 hours;
S1d.将步骤S1c所得混合物冷却，在转速8000rpm下离心，用蒸馏水和乙醇溶液多次洗涤所得固体，并在70℃干燥10h，得到前驱体；S1d. Cool the mixture obtained in step S1c, centrifuge at a rotation speed of 8000 rpm, wash the obtained solid with distilled water and ethanol solution several times, and dry at 70°C for 10 hours to obtain a precursor;
S2.将步骤S1所得前驱体用管式炉在N 2氛围下，升温至550℃恒温煅烧4h，升温速率为 7℃/min，随炉冷却，用蒸馏水将所得产物洗至中性，过滤，在70℃干燥6h即得。 S2. Use a tube furnace to heat the precursor obtained in step S1 to 550°C for 4 hours at a constant temperature of 550°C for 4 hours in an atmosphere of N 2 . Cool with the furnace, wash the resulting product with distilled water until it is neutral, and filter it. Dry at 70°C for 6h.
实施例4Example 4
本实施例制备了一种负极材料，具体过程为：In this embodiment, a negative electrode material is prepared, and the specific process is as follows:
S1.制备前驱体：S1. Preparation of precursor:
S1a.MOF原料混合：将0.01mol氯化镍、0.02mol羟基乙叉二膦酸(C 2H 8O 7P 2，HEDP)、0.02mol吡嗪(C 4H 4N 2)溶于30mL的N,N-二甲基甲酰胺(DMF)，磁力搅拌60min，使物料溶解完全； S1a. MOF raw material mixing: 0.01mol nickel chloride, 0.02mol hydroxyethylidene diphosphonic acid (C 2 H 8 O 7 P 2 , HEDP), 0.02mol pyrazine (C 4 H 4 N 2 ) were dissolved in 30mL N, N-dimethylformamide (DMF), magnetically stirred for 60 minutes to completely dissolve the material;
S1b.向步骤S1a所得混合物中加入1.5g的纳米硅，设置超声功率为70％，超声分散60min；S1b. Add 1.5 g of nano-silicon to the mixture obtained in step S1a, set the ultrasonic power to 70%, and ultrasonically disperse for 60 minutes;
S1c.将步骤S1b所得混合物移入反应釜，并于150℃反应10h；S1c. Move the mixture obtained in step S1b into a reactor, and react at 150° C. for 10 h;
S1d.将步骤S1c所得混合物冷却，在转速10000rpm下离心，用蒸馏水和乙醇溶液多次洗涤所得固体，并在60℃干燥12h，得到前驱体；S1d. Cool the mixture obtained in step S1c, centrifuge at a rotational speed of 10,000 rpm, wash the obtained solid with distilled water and ethanol solution several times, and dry at 60° C. for 12 hours to obtain a precursor;
S2.将步骤S1所得将前驱体用管式炉在N 2氛围下升温至450℃恒温煅烧6h，升温速率为2℃/min，随炉冷却，用蒸馏水将所得产物洗至中性，过滤，在70℃干燥6h即得。 S2. Use a tube furnace to heat the precursor obtained in step S1 to 450°C for 6 hours at a constant temperature under N2 atmosphere. The heating rate is 2°C/min. Cool with the furnace, wash the obtained product with distilled water until it is neutral, and filter it. Dry at 70°C for 6h.
实施例5Example 5
本实施例制备了一种负极材料，具体过程为：In this embodiment, a negative electrode material is prepared, and the specific process is as follows:
S1.制备前驱体：S1. Preparation of precursor:
S1a.MOF原料混合：将0.01mol氯化亚铁、0.01mol羟基乙叉二膦酸(C 2H 8O 7P 2，HEDP)和0.01mol吡嗪(C 4H 4N 2)溶于20mL的N,N-二甲基甲酰胺(DMF)，磁力搅拌30min，使物料溶解完全； S1a. MOF raw material mixing: Dissolve 0.01mol ferrous chloride, 0.01mol hydroxyethylidene diphosphonic acid (C 2 H 8 O 7 P 2 , HEDP) and 0.01mol pyrazine (C 4 H 4 N 2 ) in 20 mL N,N-dimethylformamide (DMF), magnetically stirred for 30min to dissolve the material completely;
S1b.向步骤S1a所得混合物中加入1g的纳米硅，设置超声功率为90％，超声分散30min；S1b. Add 1 g of nano-silicon to the mixture obtained in step S1a, set the ultrasonic power to 90%, and ultrasonically disperse for 30 minutes;
S1c.将步骤S1b所得混合物移入反应釜，并于100℃反应15h；S1c. Move the mixture obtained in step S1b into a reactor, and react at 100° C. for 15 hours;
S1d.将步骤S1c所得混合物冷却，在转速8000rpm下离心，用蒸馏水和乙醇溶液多次洗涤所得固体，在70℃干燥10h，得到前驱体；S1d. Cool the mixture obtained in step S1c, centrifuge at a rotational speed of 8000 rpm, wash the obtained solid with distilled water and ethanol solution several times, and dry at 70° C. for 10 hours to obtain a precursor;
S2.将步骤S1所得将前驱体用管式炉在N2氛围下升温至550℃恒温煅烧4h，升温速率为7℃/min，随炉冷却，用蒸馏水将所得产物洗至中性，过滤，将固体在70℃干燥6h即得。S2. Use a tube furnace to heat the precursor obtained in step S1 to 550°C for 4 hours at a constant temperature under N2 atmosphere, and calcine at a constant temperature of 7°C/min. Cool with the furnace, wash the obtained product with distilled water until it is neutral, filter, and The solid was dried at 70°C for 6h.
实施例6Example 6
本实施例制备了一种负极材料，具体过程为：In this embodiment, a negative electrode material is prepared, and the specific process is as follows:
S1.制备前驱体：S1. Preparation of precursor:
S1a.MOF原料混合：将0.01mol氯化亚铁、0.02mol羟基乙叉二膦酸(C 2H 8O 7P 2，HEDP)和0.02mol吡嗪(C 4H 4N 2)溶于30mL的N,N-二甲基甲酰胺(DMF)，磁力搅拌60min，使物 料溶解完全； S1a. MOF raw material mixing: Dissolve 0.01mol ferrous chloride, 0.02mol hydroxyethylidene diphosphonic acid (C 2 H 8 O 7 P 2 , HEDP) and 0.02mol pyrazine (C 4 H 4 N 2 ) in 30mL N,N-dimethylformamide (DMF), magnetically stirred for 60min to dissolve the material completely;
S1b.向步骤S1a所得混合物中加入1.5g的纳米硅，设置超声功率为70％，超声分散60min；S1b. Add 1.5 g of nano-silicon to the mixture obtained in step S1a, set the ultrasonic power to 70%, and ultrasonically disperse for 60 minutes;
S1c.将步骤S1b所得混合物移入反应釜，并于150℃反应10h；S1c. Move the mixture obtained in step S1b into a reactor, and react at 150° C. for 10 h;
S1d.将步骤S1c所得混合物冷却，在转速10000rpm下离心，用蒸馏水和乙醇溶液多次洗涤所得固体，并在60℃干燥12h，得到前驱体；S1d. Cool the mixture obtained in step S1c, centrifuge at a rotational speed of 10,000 rpm, wash the obtained solid with distilled water and ethanol solution several times, and dry at 60° C. for 12 hours to obtain a precursor;
S2.将步骤S1所得将前驱体用管式炉在N 2氛围下，升温至450℃恒温煅烧6h，升温速率为2℃/min，随炉冷却后，用蒸馏水洗所得产物至中性，过滤，将固体在70℃干燥6h即得。 S2. Use a tube furnace to heat the precursor obtained in step S1 to 450°C for 6 hours at a constant temperature under N 2 atmosphere. The heating rate is 2°C/min. After cooling with the furnace, wash the obtained product with distilled water until neutral, and filter , Dry the solid at 70°C for 6h.
对比例1Comparative example 1
本对比例制备了一种负极材料，与实施例4的区别在于：This comparative example has prepared a kind of negative electrode material, and the difference with embodiment 4 is:
(1)步骤S1a中的配体不包括羟基乙叉二膦酸，仅包括0.02mol的吡嗪；(1) The ligand in step S1a does not include hydroxyethylidene diphosphonic acid, but only includes 0.02mol of pyrazine;
(2)步骤S1a中的金属盐为氯化亚铁，而不是氯化镍。(2) The metal salt in step S1a is ferrous chloride, not nickel chloride.
应用例Application example
本应用例分别以实施例1～6所用纳米硅和所得负极材料为负极活性物质，制备了负极片，具体方法为：In this application example, the nano-silicon used in Examples 1-6 and the obtained negative electrode material were respectively used as the negative electrode active material to prepare the negative electrode sheet. The specific method is as follows:
D1.按重量百分数计，将15％的乙炔黑、75％的负极活性材料(分别为实施例1～6所得，以及所用纳米材料)干混搅拌后，加入5％的CMC和5％的SBR继续干混搅拌；D1. by weight percentage, after 15% acetylene black, 75% negative electrode active material (respectively embodiment 1～6 gained, and used nanometer material) dry mix and stir, add the CMC of 5% and the SBR of 5% Continue to dry mix;
D2.将步骤D1所得混合物分散至水中，形成固含量为50wt％、粘度为4500～6000cps的浆料；D2. Dispersing the mixture obtained in step D1 into water to form a slurry with a solid content of 50wt% and a viscosity of 4500-6000cps;
D3.将步骤D2所得浆料涂覆在集流体上干燥后辊压即得涂覆厚度为90～140μm(不同位置的厚度在上述范围内浮动)，压实密度为1.70～1.90g/cm 3(不同位置的压实在上述范围内浮动)。 D3. Coat the slurry obtained in step D2 on the current collector, dry it, and roll it to obtain a coating thickness of 90-140 μm (thickness at different positions fluctuates within the above range), and a compacted density of 1.70-1.90 g/cm 3 (The compaction at different positions fluctuates within the above range).
试验例Test case
本试验例测试了实施例1～6所用纳米硅和所得负极材料的电化学循环性能，测试条件为：测试电池为应用例所得负极和锂片形成的扣式电池，测试电压为0.02-1.2V，测试电流为4A/g，测试结果如图2所示。In this test example, the electrochemical cycle performance of the nano-silicon used in Examples 1 to 6 and the obtained negative electrode material is tested. The test conditions are: the test battery is a button battery formed by the negative electrode obtained in the application example and a lithium sheet, and the test voltage is 0.02-1.2V , the test current is 4A/g, and the test results are shown in Figure 2.
图2结果显示，在4A/g的高电流密度下，实施例1和3所得负极材料在800周循环后，仍保有高达可逆容量为1287.18mAh/g，容量保持率为71.8％。而以单纯纳米硅做负极活性材料时，所得电池在经历100周循环后，容量即衰减至约250mAh/g。上述结果说明，与纳米硅相比，本发明所得负极材料的循环性能明显大幅提升。The results in Figure 2 show that at a high current density of 4A/g, the anode materials obtained in Examples 1 and 3 still retain a reversible capacity of 1287.18mAh/g after 800 cycles, and the capacity retention rate is 71.8%. However, when pure nano-silicon is used as the negative electrode active material, the capacity of the resulting battery decays to about 250 mAh/g after 100 cycles. The above results show that, compared with nano-silicon, the cycle performance of the negative electrode material obtained in the present invention is significantly improved.
本实施例还测试了实施例1所得负极材料的例理化性能，具体测试了负极材料的比表面积和微观形貌。In this example, the physical and chemical properties of the negative electrode material obtained in Example 1 were also tested, specifically the specific surface area and microscopic morphology of the negative electrode material.
图3为实施例1所得负极材料的吸附脱附等温线，测试方法为：将待测粉体样品装在U型的样品管内，使含有一定比例吸附质的混合气体流过样品，根据吸附前后气体浓度变化来确定被测样品对吸附质分子(N 2)的吸附量(BET)。 Figure 3 is the adsorption-desorption isotherm of the negative electrode material obtained in Example 1. The test method is as follows: the powder sample to be tested is placed in a U-shaped sample tube, and the mixed gas containing a certain proportion of adsorbate flows through the sample. The gas concentration change is used to determine the adsorption amount (BET) of the sample to be tested for the adsorbate molecule (N 2 ).
图3结果显示，样品具有一个典型的H3回滞环，表明这是介孔材料，而在P/P0<0.02时具有很高的吸脱附量，表明其具有较多的微孔结构，即该材料是一个主要是微孔和介孔的多孔材料。通过拟合得到，本发明所得负极材料的比表面积为300～400m 2/g。 The results in Figure 3 show that the sample has a typical H3 hysteresis loop, indicating that it is a mesoporous material, and has a high adsorption and desorption capacity when P/P0<0.02, indicating that it has a more microporous structure, that is The material is a porous material which is mainly microporous and mesoporous. Through fitting, the specific surface area of the negative electrode material obtained in the present invention is 300-400 m 2 /g.
本发明所得的负极材料呈球状，主要粒径分布在1～3μm之间。具体形貌如图4所示，每个球的外层均较亮，根据质厚衬度可知，该球状物(负极材料)具有核壳结构，但是最外层的壳结构非常薄。The negative electrode material obtained by the invention is spherical, and the main particle size distribution is between 1 and 3 μm. The specific morphology is shown in Figure 4. The outer layer of each sphere is brighter. According to the mass-thickness contrast, the sphere (negative electrode material) has a core-shell structure, but the outermost shell structure is very thin.
经表征，实施例1～6所得材料的理化性能相当，均具有核壳结构和较高的比表面积。After characterization, the physical and chemical properties of the materials obtained in Examples 1 to 6 are equivalent, and all have a core-shell structure and a relatively high specific surface area.
上面结合附图对本发明实施例作了详细说明，但是本发明不限于上述实施例，在所属技术领域普通技术人员所具备的知识范围内，还可以在不脱离本发明宗旨的前提下作出各种变化。此外，在不冲突的情况下，本发明的实施例及实施例中的特征可以相互组合。The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments, and within the scope of knowledge of those of ordinary skill in the art, various modifications can be made without departing from the spirit of the present invention. Variety. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other if there is no conflict.

Claims (10)

  1. 一种负极材料，其特征在于，包括：硅基内核、包裹所述硅基内核的碳基层，以及包裹于所述碳基层表面的金属磷化物；A negative electrode material, characterized in that it comprises: a silicon-based core, a carbon-based layer wrapping the silicon-based core, and a metal phosphide wrapped on the surface of the carbon-based layer;
    所述碳基层上具有孔结构。The carbon-based layer has a pore structure.
  2. 根据权利要求1所述的负极材料，其特征在于，所述金属磷化物包括磷化铁、磷化镍、磷化钼和磷化钴中的至少一种。The negative electrode material according to claim 1, wherein the metal phosphide comprises at least one of iron phosphide, nickel phosphide, molybdenum phosphide and cobalt phosphide.
  3. 根据权利要求1所述的负极材料，其特征在于，所述负极材料的粒径为1～3μm；优选地，所述负极材料的比表面积为300～400m 2/g。 The negative electrode material according to claim 1, characterized in that the particle size of the negative electrode material is 1-3 μm; preferably, the specific surface area of the negative electrode material is 300-400 m 2 /g.
  4. 一种如权利要求1～3任一项所述负极材料的制备方法，其特征在于，包括如下步骤：A method for preparing the negative electrode material according to any one of claims 1 to 3, characterized in that it comprises the steps of:
    S1.将硅基颗粒、金属盐和配体进行溶剂热反应后固液分离，得MOF包裹的硅基颗粒；所述配体包括含磷配体；S1. Solvothermally react silicon-based particles, metal salts and ligands and then separate solids and liquids to obtain MOF-wrapped silicon-based particles; the ligands include phosphorus-containing ligands;
    S2.将所述MOF包裹的硅基颗粒在保护气氛中煅烧。S2. Calcining the MOF-wrapped silicon-based particles in a protective atmosphere.
  5. 根据权利要求4所述的制备方法，其特征在于，步骤S1中，所述含磷配体包括羟基乙叉二膦酸和草甘二膦中的至少一种；优选地，所述配体还包括含氮配体；优选地，所述金属盐包括镍盐、钴盐、钼盐和铁盐中的至少一种。The preparation method according to claim 4, characterized in that, in step S1, the phosphorus-containing ligand includes at least one of hydroxyethylidene diphosphonic acid and glyphosate; preferably, the ligand also Nitrogen-containing ligands are included; preferably, the metal salt includes at least one of nickel salt, cobalt salt, molybdenum salt and iron salt.
  6. 根据权利要求4所述的制备方法，其特征在于，步骤S1中，所述金属盐和含磷配体的摩尔比为1：(1～2)。The preparation method according to claim 4, characterized in that, in step S1, the molar ratio of the metal salt to the phosphorus-containing ligand is 1: (1-2).
  7. 根据权利要求4所述的制备方法，其特征在于，步骤S1中，所述溶剂热反应的温度为100～150℃；优选地，所述溶剂热反应的时长为10～16h。The preparation method according to claim 4, characterized in that, in step S1, the temperature of the solvothermal reaction is 100-150° C.; preferably, the duration of the solvothermal reaction is 10-16 hours.
  8. 根据权利要求4所述的制备方法，其特征在于，步骤S2中，所述煅烧的恒温温度为450～550℃；优选地，所述煅烧的恒温时长为4～6h；优选地，所述煅烧的升温速率为2～7℃/min。The preparation method according to claim 4, characterized in that, in step S2, the constant temperature of the calcination is 450-550°C; preferably, the constant temperature of the calcination is 4-6h; preferably, the calcination The heating rate is 2~7°C/min.
  9. 一种负极，其特征在于，制备原料包括权利要求1～3任一项所述的负极材料或如权利要求4～8任一项所述制备方法制得的负极材料。A negative electrode, characterized in that the preparation raw materials include the negative electrode material according to any one of claims 1-3 or the negative electrode material prepared by the preparation method according to any one of claims 4-8.
  10. 一种二次电池，其特征在于，包括如权利要求9所述的负极。A secondary battery, characterized by comprising the negative electrode according to claim 9.
PCT/CN2022/115296 2021-12-21 2022-08-26 Negative electrode material, preparation method therefor, and application thereof WO2023116020A1 (en)

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