CN112786861A - Porous carbon nanofiber coating V2O5Preparation method and application of negative electrode active material - Google Patents

Porous carbon nanofiber coating V2O5Preparation method and application of negative electrode active material Download PDF

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CN112786861A
CN112786861A CN202110100812.3A CN202110100812A CN112786861A CN 112786861 A CN112786861 A CN 112786861A CN 202110100812 A CN202110100812 A CN 202110100812A CN 112786861 A CN112786861 A CN 112786861A
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carbon nanofiber
porous carbon
active material
negative electrode
electrode active
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张训海
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Chongqing Shijiufen Technology Co ltd
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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
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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

Abstract

The invention relates to the technical field of lithium ion batteries, and discloses porous carbon nanofiber coated V2O5The negative active material takes porous carbon nanofiber as a growth site, and generates V in situ in a hydrogen peroxide hydrothermal system2O5Hollow microspheres to obtain porous carbon nanofiber coated V2O5Negative electrode active material of (1), V2O5The hollow microsphere has good structural stability and higher specific surface area, and is coated by porous carbon nanofiber under the condition of V2O5The conductive network and the ion transmission path are formed outside the hollow microspheres, so that the cathode material is obviously improvedThe multiplying power performance and the actual specific capacity are realized, and meanwhile, the porous carbon nanofiber is favorable for relieving V2O5The volume expansion phenomenon of the hollow microspheres avoids the matrix loss and decomposition of the cathode material, slows down the rapid attenuation of specific capacity, and enables the porous carbon nanofiber to coat V2O5The cathode active material has higher specific capacity, rate capability and cycling stability.

Description

Porous carbon nanofiber coating V2O5Preparation method and application of negative electrode active material
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to porous carbon nanofiber coated V2O5The preparation method and application of the negative active material.
Background
With the burning of a large amount of fossil fuels such as coal and petroleum, the problem of serious environmental pollution and the problem of energy exhaustion are caused, so that novel high-efficiency clean energy needs to be found, the problems of energy shortage and environmental pollution are solved, lithium ion batteries, fuel batteries and the like have the advantages of high energy density, stable cycle performance and the like, and have important application in portable electronic equipment, electric automobiles and energy storage power grids, but the negative electrode of a commercialized lithium ion battery is a graphite negative electrode, but the theoretical specific capacity of graphite is low, so that the development and application of the lithium ion battery are hindered.
Wherein the vanadium-based metal oxide is V2O3、V2O5The lithium ion battery cathode active material has high theoretical specific capacity, rich reserve, low price and easy obtainment, is a lithium ion battery cathode active material which is developed in the lithium ion battery cathode active material, but has V2O5Has poor conductivity and poor lithium ion diffusion coefficient, is not beneficial to the rate capability of the cathode material, and V2O5In the continuous lithium ion deintercalation process, the volume is easy to expand and change, so that the capacity is rapidly attenuated, and the cycling stability of the negative electrode material is seriously influenced, therefore, the V with high specific capacity, good rate capability and excellent cycling performance is developed2O5Negative active materials have become a research hotspot.
Technical problem to be solved
Aiming at the defects of the prior art, the invention provides a porous carbon nanofiber coated V2O5The preparation method and the application of the cathode active material solve the problem of V2O5The rate capability and the cycling stability of the cathode material are poor.
(II) technical scheme
In order to achieve the purpose, the invention provides the following technical scheme: porous carbon nanofiber coating V2O5The negative electrode active material of (3), the porous carbon nanofiber coating V2O5The method for producing the negative electrode active material of (2) is as follows:
(1) adding deionized water and vinyl acetate-polyacrylonitrile composite fiber into a reaction bottle, dropwise adding potassium hydroxide to adjust the pH of the solution to 11-12, carrying out hydrolysis reaction, filtering the solvent, and washing with deionized water to be neutral to obtain the hydroxyl-containing polyacrylonitrile composite fiber.
(2) Adding N, N-dimethylformamide solvent, hydroxyl-containing polyacrylonitrile composite fiber and O, O-dimethylphosphoryl chloride into a reaction bottle, carrying out phosphorylation reaction, cooling in ice-water bath, adding methanol for precipitation, filtering the solvent, and washing with deionized water to obtain the phosphorylated polyacrylonitrile composite fiber.
(3) And placing the phosphated polyacrylonitrile composite fiber in an atmosphere furnace for pre-carbonization to obtain a carbon nanofiber precursor.
(4) And uniformly mixing the carbon nanofiber precursor and potassium hydroxide, placing the mixture in an atmosphere furnace to perform pore-forming carbonization, and washing the carbonized product with distilled water to obtain the porous carbon nanofiber.
(5) Adding isopropanol, vanadyl acetylacetonate and porous carbon nanofiber into a beaker, performing ultrasonic dispersion for 1-3h, adding aqueous hydrogen peroxide, uniformly stirring, pouring the solution into a hydrothermal reaction kettle, performing in-situ hydrothermal reaction, cooling, filtering a solvent, and washing with deionized water to obtain porous carbon nanofiber coated V2O5The cathode active material is applied to the cathode material of the lithium ion battery.
Preferably, the vinyl acetate content of the vinyl acetate-polyacrylonitrile composite fiber in the step (1) is 5-15%, the temperature of the hydrolysis reaction is 20-40 ℃, and the reaction time is 6-12 h.
Preferably, the mass ratio of the hydroxyl-containing polyacrylonitrile composite fiber to the O, O-dimethylphosphoryl chloride in the step (2) is 100: 30-80.
Preferably, the temperature of the phosphorylation reaction in the step (2) is 70-120 ℃, and the reaction time is 8-15 h.
Preferably, the pre-carbonization in the step (3) is performed in a nitrogen atmosphere, and the pre-carbonization temperature is 500-600 ℃ and the time is 1-2 h.
Preferably, the mass ratio of the carbon nanofiber precursor to the potassium hydroxide in the step (3) is 100: 150-250.
Preferably, the pore-forming carbonization in the step (4) is carried out in a nitrogen atmosphere, the temperature of the pore-forming carbonization is 750-850 ℃, and the time is 2-3 h.
Preferably, the vanadyl acetylacetonate, the porous carbon nanofibers and the H in the step (5)2O2The mass ratio of (1) is 100:6-15: 140-180.
Preferably, the temperature of the in-situ hydrothermal reaction in the step (5) is 170-190 ℃, and the reaction time is 18-30 h.
(III) advantageous technical effects
Compared with the prior art, the invention has the following chemical mechanism and beneficial technical effects:
the porous carbon nanofiber coating V2O5The negative active material of the composite fiber is prepared by reacting ester group in the composite fiber of vinyl acetate-polyacrylonitrile in an alkaline system of potassium hydroxide, hydrolyzing to generate hydroxyl to obtain polyacrylonitrile composite fiber containing hydroxyl, further carrying out phosphorylation reaction on the hydroxyl and phosphoryl chloride groups of O, O-dimethyl phosphoryl chloride to obtain the phosphorylated polyacrylonitrile composite fiber with side chains containing phosphate groups, taking polyacrylonitrile as a carbon source and a nitrogen source, taking the phosphate groups of the side chains as a phosphorus source, the nitrogen and phosphorus doped porous carbon nanofiber is obtained by pre-carbonization and potassium hydroxide etching pore-making carbonization, not only has rich pore channel structure and ultra-high specific surface area, meanwhile, nitrogen doping is beneficial to improving the conductivity of the carbon nano fiber, promoting the adsorption of lithium ions, improving the lithium storage capacity, and phosphorus doping is beneficial to enhancing the graphitization degree of the carbon nanofiber, so that the porous carbon nanofiber with excellent electrochemical performance is obtained.
The porous carbon nanofiber coating V2O5The negative active material takes porous carbon nanofiber as a growth site, and generates V in situ in a hydrogen peroxide hydrothermal system2O5Hollow microspheres to obtain porous carbon nanofiber coated V2O5Negative electrode active material of (1), V2O5The hollow microsphere has good structural stability and higher specific surface area, and is coated by porous carbon nanofiber under the condition of V2O5A conductive network and an ion transmission path are formed on the outer side of the hollow microsphere, so that the rate capability and the actual specific capacity of the anode material are obviously improved, and meanwhile, the porous carbon nanofiber is favorable for relieving V2O5The volume expansion phenomenon of the hollow microspheres avoids the matrix loss and decomposition of the cathode material, slows down the rapid attenuation of specific capacity, and enables the porous carbon nanofiber to coat V2O5The cathode active material has higher specific capacity, rate capability and cycling stability.
Detailed Description
To achieve the above object, the present invention provides the following embodiments and examples: a preparation method of a negative electrode active material of V2O5 coated by porous carbon nanofiber is as follows:
(1) adding deionized water and vinyl acetate-polyacrylonitrile composite fiber with the vinyl acetate content of 5-15% into a reaction bottle, dropwise adding potassium hydroxide to adjust the pH value of the solution to 11-12, carrying out hydrolysis reaction for 6-12h at 20-40 ℃, filtering the solvent, and washing with deionized water to be neutral to obtain the hydroxyl-containing polyacrylonitrile composite fiber.
(2) Adding N, N-dimethylformamide solvent, hydroxyl-containing polyacrylonitrile composite fiber and O, O-dimethylphosphoryl chloride in a mass ratio of 100:30-80 into a reaction bottle, performing phosphorylation reaction for 8-15h at 70-120 ℃, cooling in ice water bath, adding methanol for precipitation, filtering the solvent, and washing with deionized water to obtain the phosphorylated polyacrylonitrile composite fiber.
(3) And placing the phosphated polyacrylonitrile composite fiber in an atmosphere furnace, and pre-carbonizing for 1-2h at the temperature of 500-600 ℃ in a nitrogen atmosphere to obtain the carbon nanofiber precursor.
(4) Uniformly mixing the carbon nanofiber precursor and potassium hydroxide in a mass ratio of 100:150-250, placing the mixture in an atmosphere furnace, carrying out pore-forming carbonization for 2-3h in a nitrogen atmosphere at the temperature of 750-850 ℃, and washing the carbonized product with distilled water to obtain the porous carbon nanofiber.
(5) Adding isopropanol, vanadyl acetylacetonate and porous carbon nanofiber into a beaker, performing ultrasonic dispersion for 1-3H, and adding aqueous hydrogen peroxide, wherein vanadyl acetylacetonate, porous carbon nanofiber and H2O2The mass ratio of the solvent to the porous carbon nanofiber is 100:6-15:140, the solution is poured into a hydrothermal reaction kettle after being uniformly stirred, the in-situ hydrothermal reaction is carried out for 18-30h at the temperature of 190 ℃, the solution is cooled, the solvent is filtered, and the solution is washed by deionized water to obtain porous carbon nanofiber coated V2O5The cathode active material is applied to the cathode material of the lithium ion battery.
Adding porous carbon nanofiber coating V into N-methyl pyrrolidone solvent2O5The slurry is coated on the surface of copper foil, dried and pressed to obtain the working electrode of the negative electrode of the lithium ion battery, the working positive electrode of the lithium sheet and a polypropylene porous membrane are used as diaphragms, and 1mol/L LiPF is adopted6The ethylene carbonate and dimethyl carbonate solution is used as electrolyte to assemble a button cell, and electrochemical performance test is carried out in a BT-2018A cell test system.
Example 1
(1) Adding deionized water and vinyl acetate-polyacrylonitrile composite fiber with the vinyl acetate content of 5% into a reaction bottle, dropwise adding potassium hydroxide to adjust the pH value of the solution to 11, performing hydrolysis reaction for 6 hours at the temperature of 20 ℃, filtering the solvent, and washing the solution to be neutral by the deionized water to obtain the hydroxyl-containing polyacrylonitrile composite fiber.
(2) Adding N, N-dimethylformamide solvent, hydroxyl-containing polyacrylonitrile composite fiber and O, O-dimethyl phosphoryl chloride in a mass ratio of 100:30 into a reaction bottle, performing phosphorylation reaction for 8 hours at 70 ℃, placing the reaction bottle in an ice-water bath for cooling, adding methanol for precipitation, filtering the solvent, and washing with deionized water to obtain the phosphorylated polyacrylonitrile composite fiber.
(3) And (3) placing the phosphated polyacrylonitrile composite fiber in an atmosphere furnace, and pre-carbonizing for 1h at 500 ℃ in a nitrogen atmosphere to obtain a carbon nanofiber precursor.
(4) Uniformly mixing a carbon nanofiber precursor and potassium hydroxide in a mass ratio of 100:150, placing the mixture in an atmosphere furnace, carrying out pore-forming carbonization for 2 hours at 750 ℃ in a nitrogen atmosphere, and washing the carbonized product with distilled water to obtain the porous carbon nanofiber.
(5) Adding isopropanol, vanadyl acetylacetonate and porous carbon nanofiber into a beaker, ultrasonically dispersing for 1H, and adding aqueous hydrogen peroxide, wherein vanadyl acetylacetonate, porous carbon nanofiber and H2O2The mass ratio of the components is 100:6:140, the solution is poured into a hydrothermal reaction kettle after being uniformly stirred, the in-situ hydrothermal reaction is carried out for 18 hours at the temperature of 170 ℃, the solution is cooled, the solvent is filtered, and the solution is washed by deionized water to obtain porous carbon nanofiber coated V2O5At a current density of 0.1C, for the first timeThe specific discharge capacity is 248.6mAh/g, and the first specific discharge capacity is 208.6mAh/g when the current density is 5C.
Example 2
(1) Adding deionized water and 8% vinyl acetate-polyacrylonitrile composite fiber into a reaction bottle, dropwise adding potassium hydroxide to adjust the pH of the solution to 11, carrying out hydrolysis reaction for 8 hours at 40 ℃, filtering the solvent, and washing with deionized water to be neutral to obtain the hydroxyl-containing polyacrylonitrile composite fiber.
(2) Adding N, N-dimethylformamide solvent, hydroxyl-containing polyacrylonitrile composite fiber and O, O-dimethyl phosphoryl chloride in a mass ratio of 100:45 into a reaction bottle, performing phosphorylation reaction for 12 hours at 100 ℃, placing the reaction bottle in an ice-water bath for cooling, adding methanol for precipitation, filtering the solvent, and washing with deionized water to obtain the phosphorylated polyacrylonitrile composite fiber.
(3) And (3) placing the phosphated polyacrylonitrile composite fiber in an atmosphere furnace, and pre-carbonizing at 500 ℃ for 1.5h in a nitrogen atmosphere to obtain a carbon nanofiber precursor.
(4) Uniformly mixing a carbon nanofiber precursor and potassium hydroxide in a mass ratio of 100:180, placing the mixture in an atmosphere furnace, carrying out pore-forming carbonization for 3 hours at 800 ℃ in a nitrogen atmosphere, and washing the carbonized product with distilled water to obtain the porous carbon nanofiber.
(5) Adding isopropanol, vanadyl acetylacetonate and porous carbon nanofiber into a beaker, performing ultrasonic dispersion for 2H, and adding aqueous hydrogen peroxide, wherein the vanadyl acetylacetonate, the porous carbon nanofiber and H2O2The mass ratio of the components is 100:8:150, the solution is poured into a hydrothermal reaction kettle after being uniformly stirred, the in-situ hydrothermal reaction is carried out for 24 hours at the temperature of 180 ℃, the solution is cooled, the solvent is filtered, and the solution is washed by deionized water to obtain porous carbon nanofiber coated V2O5When the current density of the cathode active material is 0.1C, the first discharge specific capacity is 286.1mAh/g, and when the current density is 5C, the first discharge specific capacity is 238.6 mAh/g.
Example 3
(1) Adding deionized water and 10% vinyl acetate-polyacrylonitrile composite fiber into a reaction bottle, dropwise adding potassium hydroxide to adjust the pH value of the solution to 12, carrying out hydrolysis reaction for 10 hours at 30 ℃, filtering the solvent, and washing with deionized water to be neutral to obtain the hydroxyl-containing polyacrylonitrile composite fiber.
(2) Adding N, N-dimethylformamide solvent, hydroxyl-containing polyacrylonitrile composite fiber and O, O-dimethyl phosphoryl chloride in a mass ratio of 100:65 into a reaction bottle, performing phosphorylation reaction for 12 hours at 100 ℃, placing the reaction bottle in an ice-water bath for cooling, adding methanol for precipitation, filtering the solvent, and washing with deionized water to obtain the phosphorylated polyacrylonitrile composite fiber.
(3) And (3) placing the phosphated polyacrylonitrile composite fiber in an atmosphere furnace, and pre-carbonizing at 550 ℃ for 1.5h in a nitrogen atmosphere to obtain a carbon nanofiber precursor.
(4) Uniformly mixing a carbon nanofiber precursor and potassium hydroxide in a mass ratio of 100:220, placing the mixture in an atmosphere furnace, carrying out pore-forming carbonization for 2.5 hours at 800 ℃ in a nitrogen atmosphere, and washing the carbonized product with distilled water to obtain the porous carbon nanofiber.
(5) Adding isopropanol, vanadyl acetylacetonate and porous carbon nanofiber into a beaker, performing ultrasonic dispersion for 2H, and adding aqueous hydrogen peroxide, wherein the vanadyl acetylacetonate, the porous carbon nanofiber and H2O2The mass ratio of the components is 100:12:165, the solution is poured into a hydrothermal reaction kettle after being uniformly stirred, the in-situ hydrothermal reaction is carried out for 24 hours at the temperature of 180 ℃, the solution is cooled, the solvent is filtered, and the solution is washed by deionized water to obtain porous carbon nanofiber coated V2O5When the current density of the negative electrode active material is 0.1C, the first discharge specific capacity is 301.2mAh/g, and when the current density is 5C, the first discharge specific capacity is 241.4 mAh/g.
Example 4
(1) Adding deionized water and vinyl acetate-polyacrylonitrile composite fiber with the vinyl acetate content of 15% into a reaction bottle, dropwise adding potassium hydroxide to adjust the pH value of the solution to 12, performing hydrolysis reaction for 12 hours at 40 ℃, filtering the solvent, and washing with deionized water to be neutral to obtain the hydroxyl-containing polyacrylonitrile composite fiber.
(2) Adding N, N-dimethylformamide solvent, hydroxyl-containing polyacrylonitrile composite fiber and O, O-dimethyl phosphoryl chloride in a mass ratio of 100:80 into a reaction bottle, performing phosphorylation reaction for 15 hours at 120 ℃, placing the reaction bottle in an ice-water bath for cooling, adding methanol for precipitation, filtering the solvent, and washing with deionized water to obtain the phosphorylated polyacrylonitrile composite fiber.
(3) And (3) placing the phosphated polyacrylonitrile composite fiber in an atmosphere furnace, and pre-carbonizing for 2 hours at 600 ℃ in a nitrogen atmosphere to obtain a carbon nanofiber precursor.
(4) Uniformly mixing a carbon nanofiber precursor and potassium hydroxide in a mass ratio of 100:250, placing the mixture in an atmosphere furnace, carrying out pore-forming carbonization for 3 hours at 850 ℃ in a nitrogen atmosphere, and washing the carbonized product with distilled water to obtain the porous carbon nanofiber.
(5) Adding isopropanol, vanadyl acetylacetonate and porous carbon nanofiber into a beaker, performing ultrasonic dispersion for 3 hours, and adding aqueous hydrogen peroxide, wherein the vanadyl acetylacetonate, the porous carbon nanofiber and H2O2The mass ratio of the components is 100:15:180, the solution is poured into a hydrothermal reaction kettle after being uniformly stirred, the in-situ hydrothermal reaction is carried out for 30 hours at 190 ℃, the solution is cooled, the solvent is filtered, and the solution is washed by deionized water to obtain porous carbon nanofiber coated V2O5When the current density of the negative electrode active material is 0.1C, the first discharge specific capacity is 236.0mAh/g, and when the current density is 5C, the first discharge specific capacity is 211.7 mAh/g.
Comparative example 1
(1) Adding deionized water and vinyl acetate-polyacrylonitrile composite fiber with the vinyl acetate content of 15% into a reaction bottle, dropwise adding potassium hydroxide to adjust the pH value of the solution to 12, performing hydrolysis reaction for 6 hours at 30 ℃, filtering the solvent, and washing with deionized water to be neutral to obtain the hydroxyl-containing polyacrylonitrile composite fiber.
(2) Adding N, N-dimethylformamide solvent, hydroxyl-containing polyacrylonitrile composite fiber and O, O-dimethyl phosphoryl chloride in a mass ratio of 100:15 into a reaction bottle, performing phosphorylation reaction for 8 hours at 100 ℃, placing the reaction bottle in an ice-water bath for cooling, adding methanol for precipitation, filtering the solvent, and washing with deionized water to obtain the phosphorylated polyacrylonitrile composite fiber.
(3) And (3) placing the phosphated polyacrylonitrile composite fiber in an atmosphere furnace, and pre-carbonizing for 2 hours at 550 ℃ in a nitrogen atmosphere to obtain a carbon nanofiber precursor.
(4) Uniformly mixing a carbon nanofiber precursor and potassium hydroxide in a mass ratio of 100:120, placing the mixture in an atmosphere furnace, carrying out pore-forming carbonization for 2 hours at 850 ℃ in a nitrogen atmosphere, and washing the carbonized product with distilled water to obtain the porous carbon nanofiber.
(5) Adding isopropanol, vanadyl acetylacetonate and porous carbon nanofiber into a beaker, ultrasonically dispersing for 1H, and adding aqueous hydrogen peroxide, wherein vanadyl acetylacetonate, porous carbon nanofiber and H2O2The mass ratio of the components is 100:2:120, the solution is poured into a hydrothermal reaction kettle after being uniformly stirred, the in-situ hydrothermal reaction is carried out for 24 hours at the temperature of 180 ℃, the solution is cooled, the solvent is filtered, and the solution is washed by deionized water to obtain porous carbon nanofiber coated V2O5When the current density of the negative electrode active material is 0.1C, the first discharge specific capacity is 175.6mAh/g, and when the current density is 5C, the first discharge specific capacity is 106.1 mAh/g.
Comparative example 2
(1) Adding deionized water and vinyl acetate-polyacrylonitrile composite fiber with the vinyl acetate content of 15% into a reaction bottle, dropwise adding potassium hydroxide to adjust the pH value of the solution to 11, carrying out hydrolysis reaction for 12 hours at 30 ℃, filtering the solvent, and washing with deionized water to be neutral to obtain the hydroxyl-containing polyacrylonitrile composite fiber.
(2) Adding N, N-dimethylformamide solvent, hydroxyl-containing polyacrylonitrile composite fiber and O, O-dimethyl phosphoryl chloride in a mass ratio of 1:1 into a reaction bottle, performing phosphorylation reaction for 12 hours at 120 ℃, placing the reaction bottle in an ice-water bath for cooling, adding methanol for precipitation, filtering the solvent, and washing with deionized water to obtain the phosphorylated polyacrylonitrile composite fiber.
(3) And (3) placing the phosphated polyacrylonitrile composite fiber in an atmosphere furnace, and pre-carbonizing at 500 ℃ for 1.5h in a nitrogen atmosphere to obtain a carbon nanofiber precursor.
(4) Uniformly mixing a carbon nanofiber precursor and potassium hydroxide in a mass ratio of 100:280, placing the mixture in an atmosphere furnace, carrying out pore-forming carbonization for 3 hours at 800 ℃ in a nitrogen atmosphere, and washing the carbonized product with distilled water to obtain the porous carbon nanofiber.
(5) Adding isopropanol, vanadyl acetylacetonate and porous carbon nanofiber into a beaker, performing ultrasonic dispersion for 3 hours, and adding aqueous hydrogen peroxide, wherein the vanadyl acetylacetonate, the porous carbon nanofiber and H2O2The mass ratio of the porous carbon nanofiber coating V to the solvent is 100:18:200, the solution is poured into a hydrothermal reaction kettle after being uniformly stirred, the in-situ hydrothermal reaction is carried out for 30 hours at 180 ℃, the solution is cooled, the solvent is filtered, and the solution is washed by deionized water to obtain the porous carbon nanofiber coating V2O5When the current density of the negative electrode active material is 0.1C, the first discharge specific capacity is 184.2mAh/g, and when the current density is 5C, the first discharge specific capacity is 127.4 mAh/g.

Claims (9)

1. Porous carbon nanofiber coating V2O5The negative electrode active material of (1), characterized in that: porous carbon nanofiber coating V2O5The method for producing the negative electrode active material of (2) is as follows:
(1) adding deionized water and vinyl acetate-polyacrylonitrile composite fiber into a reaction bottle, dropwise adding potassium hydroxide to adjust the pH of the solution to 11-12, and performing hydrolysis reaction to obtain hydroxyl-containing polyacrylonitrile composite fiber;
(2) adding N, N-dimethylformamide solvent, hydroxyl-containing polyacrylonitrile composite fiber and O, O-dimethylphosphoryl chloride into a reaction bottle, and carrying out phosphorylation reaction to obtain the phosphorylated polyacrylonitrile composite fiber;
(3) placing the phosphated polyacrylonitrile composite fiber in an atmosphere furnace for pre-carbonization to obtain a carbon nanofiber precursor;
(4) uniformly mixing a carbon nanofiber precursor and potassium hydroxide, placing the mixture in an atmosphere furnace to perform pore-forming carbonization, and washing a carbonized product with distilled water to obtain porous carbon nanofibers;
(5) adding isopropanol, vanadyl acetylacetonate and porous carbon nanofiber into a beaker, performing ultrasonic dispersion for 1-3h, adding aqueous hydrogen peroxide, stirring uniformly, pouring the solution into a hydrothermal reaction kettle, and performing in-situ hydrothermal reaction to obtain porous carbon nanofiber coated V2O5The negative electrode active material of (1).
2. The porous carbon nanofiber-coated V according to claim 12O5The negative electrode active material of (1), characterized in that: the vinyl acetate content of the vinyl acetate-polyacrylonitrile composite fiber in the step (1) is 5-15%, the temperature of hydrolysis reaction is 20-40 ℃, and the reaction time is 6-12 h.
3. The porous carbon nanofiber-coated V according to claim 12O5The negative electrode active material of (1), characterized in that: the mass ratio of the hydroxyl-containing polyacrylonitrile composite fiber to the O, O-dimethyl phosphoryl chloride in the step (2) is 100: 30-80.
4. The porous carbon nanofiber-coated V according to claim 12O5The negative electrode active material of (1), characterized in that: the temperature of the phosphorylation reaction in the step (2) is 70-120 ℃, and the reaction time is 8-15 h.
5. The porous carbon nanofiber-coated V according to claim 12O5The negative electrode active material of (1), characterized in that: the pre-carbonization in the step (3) is carried out in a nitrogen atmosphere, the pre-carbonization temperature is 500-600 ℃, and the time is 1-2 h.
6. The porous carbon nanofiber-coated V according to claim 12O5The negative electrode active material of (1), characterized in that: the mass ratio of the carbon nanofiber precursor to the potassium hydroxide in the step (3) is 100: 150-250.
7. The porous carbon nanofiber-coated V according to claim 12O5The negative electrode active material of (1), characterized in that: and (4) performing pore-forming carbonization in a nitrogen atmosphere at the temperature of 750 and 850 ℃ for 2-3 h.
8. The porous carbon nanofiber-coated V according to claim 12O5The negative electrode active material of (1), characterized in that: vanadyl acetylacetonate, porous carbon nanofiber and H in the step (5)2O2The mass ratio of (1) is 100:6-15: 140-180.
9. The porous carbon nanofiber-coated V according to claim 12O5The negative electrode active material of (1), characterized in that: the temperature of the in-situ hydrothermal reaction in the step (5) is 170-190 ℃, and the reaction time is 18-30 h.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113292861A (en) * 2021-05-21 2021-08-24 湖南飞鸿达新材料有限公司 Heat-conducting wave-absorbing composite magnetic sheet and preparation method thereof
CN113299901A (en) * 2021-05-17 2021-08-24 西北工业大学 Phosphorus-doped vanadium pentoxide/vanadium trioxide heptaoxide porous nanofiber and preparation method and application thereof
CN113912115A (en) * 2021-10-29 2022-01-11 广州钰芯传感科技有限公司 Preparation method of vanadium oxide nano material and application of vanadium oxide nano material in gas sensor

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113299901A (en) * 2021-05-17 2021-08-24 西北工业大学 Phosphorus-doped vanadium pentoxide/vanadium trioxide heptaoxide porous nanofiber and preparation method and application thereof
CN113292861A (en) * 2021-05-21 2021-08-24 湖南飞鸿达新材料有限公司 Heat-conducting wave-absorbing composite magnetic sheet and preparation method thereof
CN113912115A (en) * 2021-10-29 2022-01-11 广州钰芯传感科技有限公司 Preparation method of vanadium oxide nano material and application of vanadium oxide nano material in gas sensor

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