CN114242986A - Self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material and preparation method and application thereof - Google Patents

Self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material and preparation method and application thereof Download PDF

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CN114242986A
CN114242986A CN202111566908.5A CN202111566908A CN114242986A CN 114242986 A CN114242986 A CN 114242986A CN 202111566908 A CN202111566908 A CN 202111566908A CN 114242986 A CN114242986 A CN 114242986A
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self
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vanadium
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孙灵娜
蒋圣阳
张颖朦
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Shenzhen University
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
    • D04H1/72—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
    • D04H1/728—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged by electro-spinning
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/24—Electrodes characterised by structural features of the materials making up or comprised in the electrodes, e.g. form, surface area or porosity; characterised by the structural features of powders or particles used therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/32—Carbon-based
    • H01G11/36—Nanostructures, e.g. nanofibres, nanotubes or fullerenes
    • 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
    • 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

Abstract

The invention discloses a self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material as well as a preparation method and application thereof, wherein the method comprises the following steps: preparing a solution containing a trivalent vanadium source, an organic ligand and polyacrylonitrile; preparing the solution into composite nano fibers by adopting an electrostatic spinning technology; carrying out pre-oxidation treatment on the composite nanofiber to obtain a self-supporting multi-stage structure composite nanofiber; and carrying out heat treatment on the self-supporting multi-stage structure composite nanofiber to obtain the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material. The composite material of the present invention has a special microstructure grown on the outside of the carbon fibers, which facilitates sufficient contact of the electrode material with the electrolyte. The micro-dispersion of the active substance of the electrode material is improved, and the improvement of the performance of the whole electrochemical energy storage device is greatly facilitated. The microstructure grown outside the carbon fiber also comprises a carbon skeleton, so that the structural collapse or damage in the electrochemical reaction process can be avoided.

Description

Self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material and preparation method and application thereof
Technical Field
The invention relates to the technical field of nano materials, in particular to a self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material and a preparation method and application thereof.
Background
With the rapid increase in the demand for energy in human society, conventional energy sources represented by fossil fuels are gradually depleted, and the development of new energy sources represented by solar energy and wind energy is imminent. However, these new energy sources have instability and discontinuity in the temporal and spatial distribution. Energy conversion and storage devices represented by metal ion batteries can make up for the defect, expand the application scenes of new energy and promote the development of new energy industries. The electrode material is the core of an energy storage and conversion device, and vanadium nitride is a promising electrode material and can be used in various metal ion batteries, lithium sulfur batteries and super capacitors. However, vanadium nitride has a problem of poor conductivity, and the electrochemical performance of vanadium nitride can be improved by compounding vanadium nitride with a carbon material. A simple and convenient method is to adopt the electrostatic spinning technology to prepare the carbon nanofiber coated with the vanadium nitride. One reported preparation method is: PVP/C is prepared by adopting electrostatic spinning technology6H8O7/NH4VO3Compounding the nano belt, and mixing the prepared PVP/C6H8O7/NH4VO3Carrying out heat treatment on the composite nanobelt to obtain V2O5A porous nanobelt. Finally the prepared V2O5Placing the porous nanobelt in a high-purity graphite crucible, and using flowing NH3And nitriding the gas to obtain the VN porous nanobelt. A disadvantage of this preparation process is that NH has to be used3The cost is increased, certain potential safety hazards exist, and the concept of green chemistry is not met.
Another reported preparation method is to adopt tetravalent vanadium source vanadium acetylacetonate vanadyl as a polymer substrate, and to directly utilize N in polyacrylonitrile for nitridation, thereby omitting the subsequent ammoniation step. Vanadium nitride-based carbon nanofibers are prepared from vanadyl acetylacetonate and polyacrylonitrile and used in supercapacitor devices, for example, An et al [ j. Quadrivalent vanadyl acetylacetonate is adopted as the wrinkle on the surface of the nanofiber prepared by the vanadium source, other microstructures do not exist outside the nanofiber, and the prepared vanadium nitride-based carbon nanofiber has lower electrochemical performance when being used as an electrode material.
Accordingly, the prior art is yet to be improved and developed.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide a vanadium nitride-based carbon nanofiber composite material with a self-supporting multilevel structure, and a preparation method and application thereof, and aims to solve the problem that the existing vanadium nitride-based carbon nanofiber is low in electrochemical performance when being used as an electrode material.
The technical scheme of the invention is as follows:
a preparation method of a self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material comprises the following steps:
preparing a solution containing a trivalent vanadium source, an organic ligand and polyacrylonitrile;
preparing the solution containing the trivalent vanadium source, the organic ligand and the polyacrylonitrile into composite nanofibers by adopting an electrostatic spinning technology;
carrying out pre-oxidation treatment on the composite nanofiber to obtain a self-supporting multi-stage structure composite nanofiber;
and carrying out heat treatment on the self-supporting multi-stage structure composite nanofiber to obtain the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material.
Optionally, the trivalent vanadium source is selected from one or more of vanadium fluoride, vanadium chloride, vanadium bromide and vanadium iodide.
Optionally, the organic ligand is selected from one or more of 1,3, 5-benzene tricarboxylic acid, 1, 4-cyclohexane dicarboxylic acid, 1, 4-benzene dicarboxylic acid, 1, 4-naphthalene dicarboxylic acid and 5-hydroxyisophthalic acid.
Optionally, in the solution containing the trivalent vanadium source, the organic ligand and the polyacrylonitrile, the mass ratio of the trivalent vanadium source, the organic ligand and the polyacrylonitrile is (1-2): 0-2): 1-3.
Optionally, the solution containing the trivalent vanadium source, the organic ligand and the polyacrylonitrile is prepared by the following method: dissolving a trivalent vanadium source, an organic ligand and polyacrylonitrile in a polar organic solvent, and stirring to obtain a solution containing the trivalent vanadium source, the organic ligand and the polyacrylonitrile; wherein the mass ratio of the total mass of the trivalent vanadium source, the organic ligand and the polyacrylonitrile to the polar organic solvent is 0.1-0.3.
Optionally, the polar organic solvent is selected from one or more of N-N dimethylformamide, dimethyl sulfoxide and ethylene nitrate.
Optionally, when electrostatic spinning is performed, the voltage is 15-25 keV, the environmental humidity is controlled at 10% -30%, the rotating speed of the collecting roller is 300-600 r/min, and the distance between the metal needle and the collecting roller is 10-25 cm.
Optionally, the step of performing pre-oxidation treatment on the composite nanofibers specifically includes: and (3) under the air atmosphere, keeping the temperature of the composite nanofiber at 150-250 ℃ for 6-12 h at the heating rate of 1-5 ℃/min.
Optionally, the step of performing heat treatment on the self-supporting multilevel structure composite nanofiber specifically includes: and (3) in a protective atmosphere, keeping the temperature of the self-supporting multi-stage structure composite nanofiber at 600-900 ℃ for 1-5 h at a heating rate of 1-5 ℃/min.
The invention relates to a self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material, which is prepared by adopting the preparation method of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material.
The self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material disclosed by the invention is applied to lithium ion batteries, sodium ion batteries, water system zinc ion batteries, lithium sulfur batteries or super capacitors as an electrode material.
The invention has the following beneficial effects:
(1) the invention provides a novel self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material with a special microstructure, and the microstructure is beneficial to the contact of an electrode material and an electrolyte, so that the interface impedance is reduced, and the energy consumption is reduced;
(2) the external microstructure of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material prepared by the method is also supported by a unique carbon skeleton structure, so that the electrochemical stability of an electrode material is facilitated;
(3) the vanadium nitride prepared by the invention is uniformly dispersed in the carbon nanofibers and the secondary carbon skeleton growing outwards in a nanoparticle state, has high dispersibility, and improves the utilization rate of electrode materials to a great extent;
(4) the preparation process of the invention does not need subsequent ammoniation treatment, and the selected high molecular polyacrylonitrile is not only a carbon source but also a nitrogen source, thus conforming to the concept of atom economy and green chemistry;
(5) the invention has not very strict selection of preparation conditions, can be flexibly adjusted in a larger range, and selectively and reasonably collocates experimental parameters such as temperature interval, reaction time and reaction solution concentration.
Drawings
FIG. 1 is a scanning electron microscope image of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite prepared in example 1 after a second heat treatment;
FIG. 2 is a transmission electron microscope image of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite prepared in example 1 after the second heat treatment;
FIG. 3 is an X-ray diffraction pattern of the self-supporting multi-stage structural vanadium nitride-based carbon nanofiber composite prepared in example 1 after a second heat treatment;
FIG. 4 is a graph of the cycle performance of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material prepared in example 1 for a self-supporting aqueous zinc-ion battery positive electrode material;
FIG. 5 is a graph of rate performance of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material prepared in example 1 for a self-supporting aqueous zinc-ion battery positive electrode material;
FIG. 6 is a scanning electron microscope image of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite prepared in example 2 after the second heat treatment;
fig. 7 is a scanning electron microscope image of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material prepared in example 3 after the second heat treatment.
Detailed Description
The invention provides a self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material as well as a preparation method and application thereof, and the invention is further described in detail below in order to make the purpose, technical scheme and effect of the invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
At present, a preparation method is adopted to prepare vanadium nitride-based carbon nanofibers from vanadyl acetylacetonate and polyacrylonitrile and use the carbon nanofibers for a supercapacitor device, wherein tetravalent vanadyl acetylacetonate is used as a vanadium source, the polyacrylonitrile is used as a polymer substrate, and N in the polyacrylonitrile is directly used for nitridation, so that a subsequent ammoniation step is omitted. However, wrinkles exist on the surface of the nanofiber prepared by the method, other microstructures do not exist outside the nanofiber, and the prepared vanadium nitride-based carbon nanofiber serving as an electrode material is low in electrochemical performance.
In order to improve the electrochemical performance of the vanadium nitride-based carbon nanofiber as an electrode material, the embodiment provides a preparation method of a self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material with a unique microstructure. The self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material prepared by the embodiment of the invention grows a unique nanocrystalline secondary structure, such as a needle-shaped or sheet-shaped structure, outside the carbon fiber. The synthesis process is simple, green, environment-friendly and safe; the reaction conditions are easy to obtain, and the applicable objects are wide; is easy for large-scale preparation.
Specifically, the embodiment of the invention provides a preparation method of a vanadium nitride-based carbon nanofiber composite material with a self-supporting multilevel structure, which comprises the following steps:
s1, preparing a solution containing a trivalent vanadium source, an organic ligand and polyacrylonitrile;
s2, preparing the solution containing the trivalent vanadium source, the organic ligand and the polyacrylonitrile into composite nanofibers by adopting an electrostatic spinning technology;
s3, carrying out pre-oxidation treatment on the composite nanofiber to obtain a self-supporting multi-stage structure composite nanofiber;
s4, carrying out heat treatment on the self-supporting multi-stage structure composite nanofiber to obtain the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material.
In the embodiment, a solution containing a trivalent vanadium source, an organic ligand and polyacrylonitrile is prepared first, and the solution is used as a spinning solution; then preparing the spinning solution into composite nanofibers of metal-organic framework Materials (MOFs) based on vanadium metal by adopting an electrostatic spinning technology; then, carrying out pre-oxidation treatment on the composite nanofiber formed by spinning, and growing an MOFs crystal secondary structure (such as a needle-shaped or sheet-shaped structure) through solid-phase reaction to form the self-supporting multi-stage structure composite nanofiber; and finally, further performing heat treatment on the self-supporting multi-stage structure composite nanofiber to obtain the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material. In an inert atmosphere, e.g. N2After the heat treatment, the original organic polymer nanofibers are carbonized into carbon nanofibers. Due to the fact that the proportion of the graphite carbon is increased, the conductivity of the carbon nanofiber is greatly improved, and the carbon nanofiber has certain mechanical strength and can be used as a self-supporting electrode to be applied to electrochemical research and energy storage.
Compared with the vanadium nitride-based carbon nanofiber prepared in the past, the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite (serving as an electrode material) prepared in the embodiment has a special microstructure (namely a nanocrystalline secondary structure such as a needle-shaped or sheet-shaped structure) grown outside the carbon fiber, and the special microstructure is favorable for the sufficient contact between the electrode material and an electrolyte. Meanwhile, the active substance (namely vanadium nitride) of the electrode material is uniformly dispersed in the carbon nanofiber and the secondary carbon skeleton growing outwards in a nanoparticle state, and the micro-dispersibility of the active substance is improved, so that the utilization rate of the electrode material is improved, and the improvement of the performance of the whole electrochemical energy storage device is greatly facilitated. It is worth mentioning that the microstructure grown outside the carbon fiber also comprises a carbon skeleton, which can prevent the structure from collapsing or damaging in the electrochemical reaction process, thereby improving the electrochemical stability of the electrode material.
The vanadium nitride-based carbon nanofiber composite material prepared by the method has a special multi-level microstructure, and can be applied to the fields of electrochemistry and energy storage such as metal ion batteries, lithium sulfur batteries and the like. In addition, the preparation process of the embodiment is simple, subsequent ammonia nitriding treatment is not needed, the preparation method is safe and environment-friendly, large-scale preparation is easy, and the preparation method has a wide application prospect.
In step S1, in one embodiment, the solution containing the trivalent vanadium source, the organic ligand, and the polyacrylonitrile is prepared by the following method: dissolving a trivalent vanadium source, an organic ligand and polyacrylonitrile in a polar organic solvent (such as one or more of N-N dimethylformamide, dimethyl sulfoxide, ethylene nitrate and the like), and stirring (such as ultrasonic stirring till uniform mixing) to obtain a solution containing the trivalent vanadium source, the organic ligand and the polyacrylonitrile; wherein the mass ratio of the total mass of the trivalent vanadium source, the organic ligand and the polyacrylonitrile to the polar organic solvent is 0.1-0.3. Under the selected mass ratio, the prepared spinning solution has moderate viscosity, and the size of the spinning fiber is easy to regulate and control; and the spun fiber is easy to form and maintain flexibility.
In one embodiment, the trivalent vanadium source is selected from one or more of vanadium fluoride, vanadium chloride, vanadium bromide, vanadium iodide, and the like, but is not limited thereto. Wherein, the selected trivalent vanadium source is close to the trivalent valence of vanadium in vanadium nitride, and compared with vanadium sources with other valence states, the trivalent vanadium source is more beneficial to forming stable vanadium nitride. In addition, the trivalent vanadium source is favorable for forming MOFs structure with organic ligand.
In one embodiment, the organic ligand is selected from the group consisting of, but not limited to, 1,3, 5-benzenetricarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, 1, 4-benzenedicarboxylic acid, 1, 4-naphthalenedicarboxylic acid, 5-hydroxyisophthalic acid, and the like. Carboxyl groups in the selected organic ligands can be coordinated with vanadium metal ions, so that stable coordinated MOFs structures are formed.
In one embodiment, in the solution containing the trivalent vanadium source, the organic ligand and the polyacrylonitrile, the mass ratio of the trivalent vanadium source to the organic ligand to the polyacrylonitrile is (1-2): 0-2): 1-3. The mass ratio is selected, so that on one hand, a trivalent vanadium source and an organic ligand are facilitated to form a stably coordinated MOFs structure; on the other hand, the organic ligand and polyacrylonitrile are carbonized after heat treatment, and the ratio of the vanadium nitride content to the carbon content is favorable for the final electrochemical performance to be exerted efficiently.
In step S2, in one embodiment, during the electrostatic spinning, the voltage is 15-25 keV, the environmental humidity is controlled at 10% -30%, the rotation speed of the collecting roller is 300-600 r/min, and the distance between the metal needle and the collecting roller is 10-25 cm. The purpose of controlling the ambient humidity is the following two aspects: firstly, the lower environmental humidity is beneficial to the volatilization of the solvent, the diameter of the spinning nanofiber can be reduced, and the thickness of the nanofiber is more uniform; secondly, trivalent vanadium salt is easy to absorb water, and the structure of the product is changed after water absorption, so that the humidity of the spinning environment is controlled to be 10-30%.
In this embodiment, the composite nanofibers produced by electrospinning are collected on a metal foil by a collecting roller, and the composite nanofibers are subsequently peeled therefrom. Further, the metal foil may be one of aluminum foil, copper foil, zinc foil, stainless steel foil, and the like.
In step S3, in one embodiment, the step of performing a pre-oxidation treatment on the composite nanofiber specifically includes: and (3) under the air atmosphere, keeping the temperature of the composite nanofiber at 150-250 ℃ for 6-12 h at the heating rate of 1-5 ℃/min. In the process, the trivalent vanadium source and the MOF organic ligand are subjected to solid-phase reaction to grow a secondary structure of MOFs crystals, and the self-supporting multi-stage structure composite nanofiber is formed. The selected pre-oxidation temperature range is beneficial to the full occurrence of the solid-phase reaction of the MOFs, and the complete proceeding of the solid-phase reaction can be ensured by prolonging the heat treatment time.
In step S4, in one embodiment, the step of heat-treating the self-supporting multi-stage structure composite nanofiber comprises: and (3) in a protective atmosphere, keeping the temperature of the self-supporting multi-stage structure composite nanofiber at 600-900 ℃ for 1-5 h at a heating rate of 1-5 ℃/min. Further, the protective atmosphere is one or a mixture of two or more of nitrogen, helium and argon. Within the selected calcining temperature range, the organic polymer fibers are completely carbonized, nitrogen in polyacrylonitrile can react with vanadium-based-MOFs generated by pre-oxidation to generate carbon-coated vanadium nitride nano particles, the proportion of graphite to carbon is increased, the conductivity of the product is improved, and the structural stability is enhanced. If the temperature is too low, the graphitization is incomplete, and the conductivity of the carbon fiber is poor; however, the mechanical strength of the carbon fiber is deteriorated due to the excessive temperature, which is not favorable for the use as a self-supporting electrode. The temperature rise speed is not suitable to be too fast, otherwise, the secondary structure on the surface of the vanadium nitride carbon nanofiber is damaged in the heat treatment process.
In this embodiment, the self-supporting multi-level structure composite nanofiber is further subjected to heat treatment, so that the self-supporting multi-level structure vanadium nitride-based carbon nanofiber composite material can be obtained. Further, the diameter of the vanadium nitride-based carbon nanofiber composite material with the self-supporting multilevel structure is 200-400 nm.
The embodiment of the invention provides a self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material, wherein the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material is prepared by the preparation method of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material.
The self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material is applied to lithium ion batteries, sodium ion batteries, water system zinc ion batteries, lithium sulfur batteries or super capacitors as an electrode material.
The invention is further illustrated by the following specific examples.
Example 1
Using vanadium chloride (VCl)3) The method for preparing the self-supporting multi-level structure vanadium nitride-based carbon nanofiber composite material by taking 1, 4-phthalic acid as an organic ligand as a trivalent vanadium source comprises the following steps:
preparing a solution containing vanadium chloride, 1, 4-phthalic acid and polyacrylonitrile: dissolving vanadium chloride, 1, 4-phthalic acid and polyacrylonitrile in N, N-dimethylformamide, and performing ultrasonic treatment for 1h to form a uniform solution; wherein the mass ratio of the total mass of the vanadium chloride, the 1, 4-phthalic acid and the polyacrylonitrile to the mass of the N, N-dimethylformamide is 0.2.
Carrying out electrostatic spinning: the voltage is 18keV, the environmental humidity during spinning is controlled at 20%, the rotating speed of the collecting roller is 350r/min, and the distance between the metal needle and the collecting roller is 15 cm. And collecting the composite nano-fibers on the aluminum foil, and stripping the composite nano-fibers from the aluminum foil.
Carrying out annealing treatment twice: firstly, under the air atmosphere, the composite nanofiber is kept at 200 ℃ for 6h at the heating rate of 2 ℃/min, and the self-supporting multilevel-structure composite nanofiber is obtained. And then preserving the temperature of the self-supporting multi-stage structure composite nanofiber at 800 ℃ for 2h at the heating rate of 2 ℃/min under the protective atmosphere to obtain the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material. The annealed vanadium nitride-based carbon nanofiber has certain mechanical strength and can be directly used as a self-supporting positive electrode of a water-based zinc ion battery.
Fig. 1 is a scanning electron microscope image of the vanadium nitride-based carbon nanofiber composite material with the self-supporting multi-level structure prepared in this example, and it can be known from fig. 1 that a uniform and dense needle-shaped MOFs nanocrystal secondary structure is successfully grown on the surface of the nanofiber prepared in this example, and such a characteristic morphology is maintained after carbonization.
Fig. 2 is a projection electron microscope image of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material prepared in the present embodiment, and it can be known from fig. 2 that vanadium nitride nanoparticles are uniformly dispersed in carbonized carbon nanofibers, which is beneficial to improving the utilization rate and structural stability of the electrode material.
Fig. 3 is an X-ray diffraction pattern of the vanadium nitride-based carbon nanofiber composite material having a self-supporting multi-stage structure obtained in this example, and it can be seen from fig. 3 that the phase of the nanoparticle coated in the obtained composite carbon nanofiber is vanadium nitride.
Fig. 4 is a graph of the cycle performance of the self-supporting multi-stage vanadium nitride-based carbon nanofiber composite material prepared in the embodiment for the self-supporting aqueous zinc ion battery cathode material, and as can be seen from fig. 4, a battery device prepared by using the self-supporting multi-stage vanadium nitride-based carbon nanofiber composite material as an electrode material has good cycle stability and high specific capacity.
Fig. 5 is a graph of the rate performance of the self-supporting multi-stage vanadium nitride-based carbon nanofiber composite material prepared in the embodiment for the self-supporting aqueous zinc ion battery cathode material, and as can be seen from fig. 5, a battery device prepared by using the self-supporting multi-stage vanadium nitride-based carbon nanofiber composite material as an electrode material has good rate performance and still has high specific capacity when charged and discharged under a large current.
Example 2
This example differs from example 1 in that: the dosage of the 1, 4-phthalic acid is halved, namely the mass ratio of the vanadium chloride, the 1, 4-phthalic acid and the polyacrylonitrile is changed to 1:0.5: 1.6. The other steps and parameters were the same as in example 1.
Fig. 6 is a scanning electron microscope image of the vanadium nitride-based carbon nanofiber composite material with the self-supporting multi-stage structure prepared in the embodiment. As can be seen from fig. 6, the secondary structure of the needle-like nanocrystals grown on the surface of the vanadium nitride-based carbon nanofibers prepared under these conditions was less sparse and less uniform than that of example 1.
Example 3
This example differs from example 1 in that: the dosage of the 1, 4-phthalic acid is further reduced, namely the mass ratio of the vanadium chloride, the 1, 4-phthalic acid and the polyacrylonitrile is changed to 1:0.1: 1.6. The other steps and parameters were the same as in example 1.
Fig. 7 is a scanning electron microscope image of the vanadium nitride-based carbon nanofiber composite material with the self-supporting multi-stage structure prepared in the embodiment. As can be seen from fig. 7, the nanocrystalline secondary structure grown on the surface of the vanadium nitride-based carbon nanofiber prepared under the conditions is flaky.
In summary, the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material and the preparation method and application thereof provided by the invention have the advantages that the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material prepared by the invention has a special microstructure growing outside carbon fibers, and the electrode material is in full contact with electrolyte. Meanwhile, the micro-dispersibility of the active substances of the electrode material is improved, and the improvement of the performance of the whole electrochemical energy storage device is greatly facilitated. It should be noted that the microstructure of the carbon fiber grown outside also includes a carbon skeleton, which can prevent the structure from collapsing or breaking during the electrochemical reaction. The self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material can be applied to the fields of electrochemistry and energy storage such as metal ion batteries, lithium sulfur batteries and the like. In addition, the preparation method disclosed by the invention is simple in preparation process, safe and environment-friendly, does not need subsequent ammonia nitriding treatment, is easy for large-scale preparation, and has a wide application prospect.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims (10)

1. A preparation method of a self-supporting multi-level structure vanadium nitride-based carbon nanofiber composite material is characterized by comprising the following steps:
preparing a solution containing a trivalent vanadium source, an organic ligand and polyacrylonitrile;
preparing the solution containing the trivalent vanadium source, the organic ligand and the polyacrylonitrile into composite nanofibers by adopting an electrostatic spinning technology;
carrying out pre-oxidation treatment on the composite nanofiber to obtain a self-supporting multi-stage structure composite nanofiber;
and carrying out heat treatment on the self-supporting multi-stage structure composite nanofiber to obtain the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material.
2. The preparation method of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material as claimed in claim 1, wherein the trivalent vanadium source is one or more selected from vanadium fluoride, vanadium chloride, vanadium bromide and vanadium iodide.
3. The preparation method of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material as claimed in claim 1, wherein the organic ligand is one or more selected from 1,3, 5-benzenetricarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, 1, 4-benzenedicarboxylic acid, 1, 4-naphthalenedicarboxylic acid and 5-hydroxyisophthalic acid.
4. The preparation method of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material as claimed in claim 1, wherein in the solution containing the trivalent vanadium source, the organic ligand and the polyacrylonitrile, the mass ratio of the trivalent vanadium source, the organic ligand and the polyacrylonitrile is (1-2): (0-2): (1-3).
5. The preparation method of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material as claimed in claim 1, wherein the solution containing the trivalent vanadium source, the organic ligand and the polyacrylonitrile is prepared by the following method: dissolving a trivalent vanadium source, an organic ligand and polyacrylonitrile in a polar organic solvent, and stirring to obtain a solution containing the trivalent vanadium source, the organic ligand and the polyacrylonitrile; wherein the mass ratio of the total mass of the trivalent vanadium source, the organic ligand and the polyacrylonitrile to the polar organic solvent is 0.1-0.3; the polar organic solvent is one or more selected from N-N dimethylformamide, dimethyl sulfoxide and ethylidene nitrate.
6. The method for preparing the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material as claimed in claim 1, wherein electrostatic spinning is performed under a voltage of 15-25 keV and an ambient humidity of 10-30%, the rotation speed of the collecting roller is 300-600 r/min, and the distance between the metal needle and the collecting roller is 10-25 cm.
7. The method for preparing the vanadium nitride-based carbon nanofiber composite material with the self-supporting multilevel structure according to claim 1, wherein the step of pre-oxidizing the composite nanofibers specifically comprises: and (3) under the air atmosphere, keeping the temperature of the composite nanofiber at 150-250 ℃ for 6-12 h at the heating rate of 1-5 ℃/min.
8. The method for preparing the vanadium nitride-based carbon nanofiber composite material with the self-supporting multilevel structure according to claim 1, wherein the step of performing heat treatment on the self-supporting multilevel structure composite nanofiber specifically comprises: and (3) in a protective atmosphere, keeping the temperature of the self-supporting multi-stage structure composite nanofiber at 600-900 ℃ for 1-5 h at a heating rate of 1-5 ℃/min.
9. The self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material is characterized by being prepared by the preparation method of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material according to any one of claims 1 to 8.
10. The use of the self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material of claim 9 as an electrode material in a lithium ion battery, a sodium ion battery, an aqueous zinc ion battery, a lithium sulfur battery, or a supercapacitor.
CN202111566908.5A 2021-12-17 2021-12-17 Self-supporting multi-stage structure vanadium nitride-based carbon nanofiber composite material and preparation method and application thereof Pending CN114242986A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114843467A (en) * 2022-04-28 2022-08-02 华南师范大学 Nitrogen-phosphorus co-doped vanadium oxide/carbon self-supporting electrode material and preparation method and application thereof
CN115010502A (en) * 2022-05-25 2022-09-06 松山湖材料实验室 Method for rapidly preparing nano vanadium nitride coated carbon fiber composite ceramic powder, product and application thereof

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114843467A (en) * 2022-04-28 2022-08-02 华南师范大学 Nitrogen-phosphorus co-doped vanadium oxide/carbon self-supporting electrode material and preparation method and application thereof
CN115010502A (en) * 2022-05-25 2022-09-06 松山湖材料实验室 Method for rapidly preparing nano vanadium nitride coated carbon fiber composite ceramic powder, product and application thereof
CN115010502B (en) * 2022-05-25 2023-05-16 松山湖材料实验室 Method for rapidly preparing nano vanadium nitride coated carbon fiber composite ceramic powder, product and application thereof

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