CN116190666A - Positive electrode material and preparation method and application thereof - Google Patents

Positive electrode material and preparation method and application thereof Download PDF

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CN116190666A
CN116190666A CN202310488820.9A CN202310488820A CN116190666A CN 116190666 A CN116190666 A CN 116190666A CN 202310488820 A CN202310488820 A CN 202310488820A CN 116190666 A CN116190666 A CN 116190666A
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sodium
vanadium
positive electrode
mesogenic
phosphate
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陈以蒙
江柯成
王迪
张继宗
蒋绮雯
司煜
董丰恺
王翔翔
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Jiangsu Zenergy Battery Technologies 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
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    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
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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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
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    • H01M4/00—Electrodes
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
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    • 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
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
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    • 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
    • H01M2004/028—Positive electrodes
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Abstract

The invention relates to a positive electrode material, and a preparation method and application thereof. The positive electrode material comprises a vanadium sodium phosphate composite carbon nanofiber material and a conductive mesogen wrapping layer wrapping the surface of the vanadium sodium phosphate composite carbon nanofiber material. M prepared by the invention 2 Ox mesogenic material coated carbon composite sodium vanadium phosphate nanofiber material M 2 O x On the basis of enhancing the ionic conductivity and the electronic conductivity of vanadium sodium phosphate, NVP/C stabilizes phosphorus in the charge and discharge processThe sodium vanadium oxide improves the multiplying power charge-discharge performance and the circulation stability of the anode material.

Description

Positive electrode material and preparation method and application thereof
Technical Field
The invention relates to the technical field of sodium ion batteries, in particular to a positive electrode material and a preparation method and application thereof. .
Background
Sodium vanadium phosphate (Na) 3 V 2 (PO 4 ) 3 Abbreviated as NVP) is used as a typical polyanion type sodium ion battery anode material, has higher ion conductivity and excellent structural stability due to the special sodium ion superconductor (NASICON) structure, and is a sodium ion battery anode material with very good application prospect. But the material also has more pronounced short plates, due to the [ PO ] 4 ]The presence of tetrahedral structures can hinder the transport in the electronic material, resulting in very low electronic conductivity, which can further limit the reaction kinetics of the material, affecting the electrochemical properties of the material. Therefore, it is necessary to enhance the electrochemical performance thereof.
Disclosure of Invention
In order to solve the technical problems, the invention provides a positive electrode material, and a preparation method and application thereof.
The invention is realized by the following scheme:
the first object of the present invention is to provide a method for preparing a positive electrode material, comprising the steps of:
mixing a sodium source, a vanadium source, a phosphorus source, a high polymer, a carbon source and a solvent to obtain an electrostatic spinning solution, carrying out electrostatic spinning to obtain a precursor of nanofiber, and carrying out primary heat treatment to obtain a vanadium sodium phosphate composite carbon nanofiber material;
dispersing salt or oxide containing M into acid solution, reacting the obtained mixed solution at 100-200 ℃, and thenSolid phase is obtained by solid-liquid separation of reaction liquid, namely M 2 O x A mesogenic material;
combining the sodium vanadium phosphate composite carbon nanofiber material with the M 2 O x The mesogenic materials are mixed and subjected to secondary heat treatment to form M 2 O x The mesogenic coating layer is used for obtaining the anode material;
Where M is one or more of Zn, ce, ti, cu, fe, W, pb and Cd, and x is the valence of M.
In one embodiment of the present invention, the sodium source may be selected from materials conventional in the art, preferably and not limited to one or more of sodium carbonate, sodium hydroxide, sodium acetate, sodium oxalate and sodium nitrate;
in one embodiment of the present invention, the vanadium source may be selected from materials conventional in the art, preferably and not limited to one or more of vanadium powder, vanadium pentoxide, vanadium trioxide and ammonium metavanadate;
in one embodiment of the present invention, the phosphorus source may be selected from materials conventional in the art, preferably and not limited to one or more of monoammonium phosphate, diammonium phosphate, ammonium phosphate, phosphoric acid and ammonium hypophosphite.
In one embodiment of the invention, the acid in the acid solution is selected from sulfuric acid and/or nitric acid.
In one embodiment of the invention, the concentration of the acid solution is 15wt% to 35wt%.
In one embodiment of the present invention, the high molecular polymer is polyvinylpyrrolidone.
In one embodiment of the invention, the carbon source is selected from one or more of glucose, citric acid, sucrose, oxalic acid, malonic acid, malic acid and mandelic acid.
In one embodiment of the present invention, the solvent is selected from one or more of water, absolute ethanol, acetic acid, hexafluoroisopropanol, chloroform and tetrahydrofuran.
In one embodiment of the present invention, the molar ratio of sodium in the sodium source, vanadium in the vanadium source, and phosphorus in the phosphorus source is 3:2:3.
in one embodiment of the invention, the mass ratio of the carbon source to the sodium vanadium phosphate in the sodium vanadium phosphate composite carbon nanofiber material is 0.5-1.5: 100, wherein the mass ratio of the high molecular polymer to the sodium vanadium phosphate in the sodium vanadium phosphate composite carbon nanofiber material is 2-5: 1.
in one embodiment of the invention, the conditions of electrospinning: the voltage is 10 KV-15 KV, and the distance between a filament outlet and a receiver in the electrostatic spinning device is 12 cm-20 cm; the spinning speed is 0.1-0.5 mm/min, and the rotating speed of the receiver is 4-8 m/h.
In one embodiment of the present invention, the conditions of the primary heat treatment: the temperature of the heating sintering is 600-1000 ℃, the time of the heating sintering is 4-20 hours, the temperature rising rate of the heating sintering is 1-10 ℃/min, and the gas atmosphere of the heating sintering comprises the mixed gas of argon and hydrogen.
In one embodiment of the invention, the argon to hydrogen volume ratio is 85: 5-95: 5.
In one embodiment of the invention, the vanadium sodium phosphate composite carbon nanofiber material and the M 2 O x In the step of mixing the mesogenic material, the vanadium sodium phosphate composite carbon nanofiber material and the M 2 O x The mass ratio of the mesogenic material is 100:0.1 to 0.4.
In one embodiment of the invention, the vanadium sodium phosphate composite carbon nanofiber material and the M 2 O x In the step of mixing the mesogenic materials, a ball milling method is selected as a mixing method, the ball milling speed is 250 r/min-750 r/min, and the ball milling time is 1 h-6 h.
In one embodiment of the invention, the conditions of the secondary heat treatment are: the sintering temperature is 200-550 ℃, the sintering time is 3-10 h, the heating rate is 1-10 ℃/min, and the gas in the heated sintering gas atmosphere is one or more of helium, argon and nitrogen.
The second object of the invention is to provide a positive electrode material, which comprises a vanadium sodium phosphate composite carbon nanofiber material and a conductive mesogen wrapping layer wrapping the surface of the vanadium sodium phosphate composite carbon nanofiber material, namely a conductive mesogen@vanadium sodium phosphate/carbon nanofiber material, "@" represents wrapping.
In one embodiment of the present invention, the conductive mesogenic encapsulation layer comprises a conductive mesogenic material having a molecular formula of M 2 O x The method comprises the steps of carrying out a first treatment on the surface of the Where M is one or more of Zn, ce, ti, cu, fe, W, pb and Cd, and x is the valence of M.
A third object of the present invention is to provide a positive electrode sheet, which includes a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector, wherein the positive electrode active material layer includes the positive electrode material or the positive electrode material obtained by the above-mentioned preparation method.
A fourth object of the present invention is to provide a sodium ion battery including the positive electrode sheet.
Compared with the prior art, the technical scheme of the invention has the following advantages:
m prepared by the invention 2 O x Mesogen coated carbon composite sodium vanadium phosphate nanofiber material M 2 O x The @ NVP/C has the following advantages:
1. the electrostatic spinning technology is utilized to prepare the sodium vanadium phosphate composite carbon fiber, so that the particle size of the sodium vanadium phosphate material is reduced, the migration path of sodium ions in the material is effectively shortened, and meanwhile, the sodium vanadium phosphate is subjected to carbon recombination, so that the synthesis steps are simplified, the conductivity of the sodium vanadium phosphate material is improved to a certain extent, and the multiplying power performance of the material can be effectively improved.
2. M having stable structure and excellent electron conductivity is prepared 2 O x Mesogen, which moves M by high surface polarity and thermodynamics of carbon nanofibers 2 O x Mesogen is adsorbed on the NVP/C composite material to form M 2 O x NVP/C material, M 2 O x The mesogenic coating layer can effectively inhibit structural collapse of the material in the high-rate charge and discharge process, so that the structure of the material is stabilized, and the cycle stability and the high-rate discharge characteristic of the material are improved.
In summary, M prepared according to the invention 2 O x Mesogen coated carbon composite sodium vanadium phosphate nanofiber material M 2 O x On the basis of enhancing the ion conductivity and the electron conductivity of the vanadium sodium phosphate material, the NVP/C stabilizes the vanadium sodium phosphate material in the charge and discharge process and improves the rate capability and the cycle stability of the material.
Drawings
In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings, in which,
FIG. 1 shows CeO obtained in example 1 of the present invention 2 X-ray diffraction pattern of @ NVP/C;
FIG. 2 shows CeO obtained in example 1 of the present invention 2 Scanning electron microscope image of @ NVP/C;
FIG. 3 shows CeO obtained in example 1 of the present invention 2 Scanning electron microscope pictures of mesogens;
FIG. 4 is a scanning electron microscope image of sodium vanadium phosphate prepared in comparative example 1 of the present invention.
Detailed Description
To solve the problem of the prior art that the [ PO ] in the sodium vanadium phosphate material 4 ]The existence of tetrahedral structure can obstruct the transmission in the electronic material, thereby causing the technical problems of very low electronic conductivity, further restricting the reaction kinetics of the material, influencing the electrochemical performance of the material, and the like.
The invention provides a positive electrode material, and a preparation method and application thereof.
The invention also provides a preparation method of the positive electrode material, which comprises the following steps:
mixing a sodium source, a vanadium source, a phosphorus source, a high polymer, a carbon source and a solvent to obtain an electrostatic spinning solution, carrying out electrostatic spinning to obtain a precursor of nanofiber, and carrying out primary heat treatment to obtain a vanadium sodium phosphate composite carbon nanofiber material;
dispersing salt or oxide containing M into an acid solution, reacting the obtained mixed solution at 100-200 ℃, and then separating solid from liquid of the reaction solution to obtain a solid phase, namely M 2 O x A mesogenic material;
combining the sodium vanadium phosphate composite carbon nanofiber material with the M 2 O x Mesogenic material mixtureAnd then performing secondary heat treatment to form M 2 O x The mesogenic coating layer is used for obtaining the anode material;
where M is one or more of Zn, ce, ti, cu, fe, W, pb and Cd, and x is the valence of M.
Further, the sodium source may be selected from materials conventional in the art, preferably and not limited to one or more of sodium carbonate, sodium hydroxide, sodium acetate, sodium oxalate and sodium nitrate;
Further, the vanadium source may be selected from materials conventional in the art, preferably and not limited to one or more of vanadium powder, vanadium pentoxide, vanadium trioxide and ammonium metavanadate;
further, the phosphorus source may be selected from materials conventional in the art, preferably and not limited to one or more of monoammonium phosphate, diammonium phosphate, ammonium phosphate, phosphoric acid, and ammonium hypophosphite.
Further, the high molecular polymer is polyvinylpyrrolidone.
Further, the carbon source is selected from one or more of glucose, citric acid, sucrose, oxalic acid, malonic acid, malic acid and mandelic acid.
Further, the solvent is selected from one or more of water, absolute ethanol, acetic acid, hexafluoroisopropanol, chloroform and tetrahydrofuran.
Further, the molar ratio of the sodium in the sodium source, the vanadium in the vanadium source and the phosphorus in the phosphorus source is 3:2:3. wherein the excess of sodium in the sodium source is 3wt% to 5wt%. Sodium is required in excess due to losses during calcination, and sodium source in excess is a routine practice in the art.
Further, the mass ratio of the carbon source to the sodium vanadium phosphate in the sodium vanadium phosphate composite carbon nanofiber material is 0.5-1.5: 100, wherein the mass ratio of the high molecular polymer to the sodium vanadium phosphate in the sodium vanadium phosphate composite carbon nanofiber material is 2-5: 1.
Further, the conditions of the electrospinning: the voltage is 10 KV-15 KV, and the distance between a filament outlet and a receiver in the electrostatic spinning device is 12 cm-20 cm; the spinning speed is 0.1-0.5 mm/min, and the rotating speed of the receiver is 4-8 m/h.
Further, the conditions of the primary heat treatment: the temperature of the heating sintering is 600-1000 ℃, the time of the heating sintering is 4-20 hours, the temperature rising rate of the heating sintering is 1-10 ℃/min, and the gas atmosphere of the heating sintering comprises the mixed gas of argon and hydrogen.
Further, the volume ratio of argon to hydrogen is 85: 5-95: 5. preferably 90: 5. 85: 15. 95:5, etc., or any value between any two values.
Further, the vanadium sodium phosphate composite carbon nanofiber material and the M 2 O x In the step of mixing the mesogenic material, the vanadium sodium phosphate composite carbon nanofiber material and the M 2 O x The mass ratio of the mesogenic material is 100:0.1 to 0.4. Further, it is preferably 100:0.1, 100:0.15, 100:0.3, 100:0.4, etc., or any value between any two values.
Further, the vanadium sodium phosphate composite carbon nanofiber material and the M 2 O x In the step of mixing the mesogenic materials, a ball milling method is selected as a mixing method, the ball milling speed is 250 r/min-750 r/min, and the ball milling time is 1 h-6 h.
Further, the conditions of the secondary heat treatment: the sintering temperature is 200-550 ℃, the sintering time is 3-10 h, the heating rate is 1-10 ℃/min, and the gas in the heated sintering gas atmosphere is one or more of helium, argon and nitrogen.
The second object of the invention is to provide a positive electrode material, which comprises a vanadium sodium phosphate composite carbon nanofiber material and a conductive mesogen wrapping layer wrapping the surface of the vanadium sodium phosphate composite carbon nanofiber material, namely a conductive mesogen@vanadium sodium phosphate/carbon nanofiber material, "@" represents wrapping.
In one embodiment of the present invention, the conductive mesogenic encapsulation layer comprises a conductive mesogenic material having a molecular formula of M 2 O x The method comprises the steps of carrying out a first treatment on the surface of the Where M is one or more of Zn, ce, ti, cu, fe, W, pb and Cd, and x is the valence of M.
The invention also provides a positive plate which comprises a positive current collector and a positive active material layer arranged on at least one side of the positive current collector, wherein the positive active material layer comprises a positive material, a binder and a conductive agent, and the positive material comprises a conductive mesogen@sodium vanadium phosphate/carbon nanofiber material and the conductive mesogen@sodium vanadium phosphate/carbon nanofiber material obtained by the preparation method.
The embodiment of the invention also provides a sodium ion battery, which comprises the positive plate.
The preparation method of the sodium ion battery is not particularly limited, and the preparation method of the battery known to the person skilled in the art can be used.
The present invention will be further described with reference to the accompanying drawings and specific examples, which are not intended to be limiting, so that those skilled in the art will better understand the invention and practice it.
Example 1
The embodiment provides a conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber material (CeO) 2 @NVP/C) and a preparation method and application thereof are specifically as follows:
firstly, a conductive mesogen coated carbon composite vanadium sodium phosphate nanofiber material (CeO) 2 @ NVP/C) cathode material.
1. The preparation method of the vanadium sodium phosphate composite carbon nanofiber anode material NVP/C comprises the following steps: according to Na: v: p=3: 2:3 molar ratio of sodium acetate (3 percent excess), vanadium pentoxide and ammonium dihydrogen phosphate, and citric acid according to mass ratio: sodium vanadium phosphate = 0.75:100, weighing citric acid, taking deionized water as a solvent, placing the citric acid on a magnetic stirrer for stirring and dissolving, and then adding polyvinylpyrrolidone, wherein the mass ratio of polyvinylpyrrolidone to sodium vanadium phosphate is 3:1, a step of; stirring is continued to form uniform electrostatic spinning solution. Extracting the electrostatic spinning solution into a 5mL injector, and installing an electrostatic spinning needle, wherein the distance between the needle and the aluminum foil is 13.5cm, and the voltage is 13KV; the speed of the electrostatic spinning is 0.15mm/min; the rotating speed of the receiver is 6m/h, and the one-dimensional nanofiber precursor is prepared. And (3) placing the obtained nanofiber precursor in a tube furnace for heating treatment under the atmosphere of mixed gas of argon with the volume concentration of 95% and hydrogen with the volume concentration of 5%, wherein the heating rate is 4 ℃/min, heating to 850 ℃ for heat treatment for 12 hours, and cooling along with the furnace to obtain the vanadium sodium phosphate composite carbon nanofiber anode material NVP/C.
2、CeO 2 The preparation method of the mesogenic material comprises the following steps: ceO is stirred under the condition of stirring 2 Dispersing into 5mol/L concentrated sulfuric acid to obtain Ce 2 (SO 4 ) 3 Stirring for 3.5h to obtain a mixed solution; pouring the mixed solution into a reaction kettle, and placing the reaction kettle into a baking oven at 180 ℃ for reacting for 20 hours; naturally cooling after the reaction is finished to obtain white precipitate, washing the white precipitate with absolute ethyl alcohol for 5 times, centrifugally separating the white precipitate, and then placing the separated product into a blast drying oven at 80 ℃ to dry for 10 hours to obtain CeO 2 The mesogenic material has the structural characterization shown in figure 3, and the prepared CeO can be seen from figure 3 2 The mesogenic material is granular with the size distribution of 25 nm-50 nm.
3. Conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber material (CeO) 2 Preparation procedure of @ NVP/C): NVP/C of the vanadium sodium phosphate composite carbon nanofiber anode material obtained in the step 1 and CeO prepared in the step 2 2 Mesogenic material according to 100: ball milling for 4.5 hours in a ball mill with the rotating speed of 500r/min at the mass ratio of 0.4 to obtain precursor powder which is uniformly mixed; then placing the uniformly mixed powder into a tube furnace (under nitrogen atmosphere condition) with the temperature rising rate of 5 ℃/min for secondary heat treatment at 450 ℃ for 8 hours to obtain the conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber material (CeO) 2 The structural characterization is shown in figures 1-2, and a layer of nano-sized granular mesogenic material is attached to the carbon composite sodium vanadium phosphate nanofiber in figure 2, which shows that the mesogenic material is coated on the carbon composite sodium vanadium phosphate nanofiber to form the mesogenic coated carbon composite sodium vanadium phosphate nanofiber material.
(II) application of materials
The preparation of the sodium ion battery is specifically as follows:
CeO is added with 2 The weight ratio of the @ NVP/C composite material, the binder PVDF and the conductive carbon black super p is 90:5:5 grinding uniformly, adding a proper amount of NMP to prepare slurry, and uniformly coating on the pretreated aluminum foilDrying in a forced air drying oven at 80deg.C for 1 hr, and drying in a vacuum drying oven at 120deg.C for 12 hr; then cutting into 14mm round positive plates by a cutting machine. Sodium metal sheet with the diameter of 14mm and the thickness of 0.2mm is used as a negative electrode, 0.1mol/L sodium perchlorate/ethylene carbonate/dimethyl carbonate solution is used as electrolyte, whatman GF/F glass fiber with the diameter of 16mm is used as a diaphragm, and the CR2032 button cell is assembled in a glove box filled with high-purity argon.
(III) Performance test
And using a constant current charge-discharge mode to perform charge-discharge tests under different current densities. The test items include: the material is charged and discharged at the first round of 0.1C, the multiplying power of 1C/5C/10C/20C, the capacity retention rate of 200 th round of 1C and 500 th round of 1C in the sodium ion battery. CeO prepared in this example was used under the conditions of a discharge cutoff voltage of 2.0V and a charge cutoff voltage of 4.0V 2 The physicochemical properties of the @ NVP/C composite are shown in Table 1.
Example 2
The embodiment provides a conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber (CeO) 2 @NVP/C) positive electrode material, and preparation method and application thereof are as follows:
firstly, a conductive mesogen coated carbon composite vanadium sodium phosphate nanofiber material (CeO) 2 @ NVP/C).
1. The preparation method of the vanadium sodium phosphate composite carbon nanofiber anode material NVP/C comprises the following steps: according to Na: v: p=3: 2:3 molar ratio of sodium acetate (3 percent excess), vanadium pentoxide and ammonium dihydrogen phosphate, and citric acid according to mass ratio: sodium vanadium phosphate = 0.75:100, weighing citric acid, taking deionized water as a solvent, placing the citric acid on a magnetic stirrer for stirring and dissolving, and then adding polyvinylpyrrolidone. Wherein the mass ratio of polyvinylpyrrolidone to sodium vanadium phosphate is 3:1, a step of; stirring is continued to form uniform electrostatic spinning solution. Extracting the electrostatic spinning solution into a 5mL injector, and installing an electrostatic spinning needle, wherein the distance between the needle and the aluminum foil is 13.5cm, and the voltage is 13KV; the speed of electrostatic spinning is 0.15mm/min, and the rotating speed of the receiver is 6m/h, so that the one-dimensional nanofiber precursor is prepared. And (3) placing the obtained nanofiber precursor in a tube furnace for heating treatment under the atmosphere of mixed gas of argon with the volume concentration of 95% and hydrogen with the volume concentration of 5%, wherein the heating rate is 4 ℃/min, heating to 850 ℃ for heat treatment for 12 hours, and cooling along with the furnace to obtain the vanadium sodium phosphate composite carbon nanofiber anode material NVP/C.
2、CeO 2 The preparation method of the mesogenic material comprises the following steps: ceO is stirred under the condition of stirring 2 Dispersing into 5mol/L concentrated sulfuric acid to obtain Ce 2 (SO 4 ) 3 Stirring for 3.5h to obtain a mixed solution; pouring the mixed solution into a reaction kettle, and placing the reaction kettle into a baking oven at 180 ℃ for reacting for 20 hours; naturally cooling after the reaction is finished to obtain white precipitate, washing the white precipitate with absolute ethyl alcohol for 5 times, centrifugally separating the white precipitate, and then placing the separated product into a blast drying oven at 80 ℃ to dry for 10 hours to obtain CeO 2 A mesogenic material.
3. Conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber material (CeO) 2 Preparation procedure of @ NVP/C): NVP/C of the vanadium sodium phosphate composite carbon nanofiber anode material obtained in the step 1 and CeO prepared in the step 2 2 Mesogenic material according to 100: placing the mixture in a mass ratio of 0.25 into a ball mill with the rotating speed of 500 r/min for ball milling for 4.5 hours to obtain precursor powder which is uniformly mixed; then placing the uniformly mixed powder into a tube furnace (under nitrogen atmosphere condition) with the temperature rising rate of 5 ℃/min for secondary heat treatment at 450 ℃ for 8 hours to obtain the conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber material (CeO) 2 @NVP/C）。
(II) application of materials
The preparation of the sodium ion battery is specifically as follows:
CeO is added with 2 The weight ratio of the @ NVP/C composite material, the binder PVDF and the conductive carbon black super p is 90:5: grinding uniformly, adding a proper amount of NMP to prepare slurry, uniformly coating the slurry on the pretreated aluminum foil, drying the aluminum foil for 1h at 80 ℃ in a forced air drying oven, and drying the aluminum foil for 12h at 120 ℃ in a vacuum drying oven; then cutting into 14mm round positive plates by a cutting machine. Sodium metal sheet with the diameter of 14mm and the thickness of 0.2mm is used as a negative electrode, 0.1mol/L sodium perchlorate/ethylene carbonate/dimethyl carbonate solution is used as electrolyte, whatman GF/F glass fiber with the diameter of 16mm is used as a diaphragm, and CR2032 button type electricity is obtained by assembling in a glove box filled with high-purity argon And (5) a pool.
(III) Performance test
And using a constant current charge-discharge mode to perform charge-discharge tests under different current densities. The test items include: the material is charged and discharged at the first round of 0.1C, the multiplying power of 1C/5C/10C/20C, the capacity retention rate of 200 th round of 1C and 500 th round of 1C in the sodium ion battery. CeO prepared in this example was used under the conditions of a discharge cutoff voltage of 2.0V and a charge cutoff voltage of 4.0V 2 The physicochemical properties of the @ NVP/C composite are shown in Table 1.
Example 3
The embodiment provides a conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber (CeO) 2 @NVP/C) positive electrode material, and preparation method and application thereof are as follows:
firstly, a conductive mesogen coated carbon composite vanadium sodium phosphate nanofiber material (CeO) 2 @ NVP/C).
1. The preparation method of the vanadium sodium phosphate composite carbon nanofiber anode material NVP/C comprises the following steps: according to Na: v: p=3: 2:3 molar ratio of sodium acetate (3 percent excess), vanadium pentoxide and ammonium dihydrogen phosphate, and citric acid according to mass ratio: sodium vanadium phosphate = 0.75:100, weighing citric acid, taking deionized water as a solvent, placing the citric acid on a magnetic stirrer for stirring and dissolving, and then adding polyvinylpyrrolidone, wherein the mass ratio of polyvinylpyrrolidone to sodium vanadium phosphate is 3:1, continuing stirring to form uniform electrostatic spinning solution. Extracting the electrostatic spinning solution into a 5mL injector, and installing an electrostatic spinning needle, wherein the distance between the needle and the aluminum foil is 13.5cm, and the voltage is 13KV; the speed of the electrostatic spinning is 0.15mm/min; the rotating speed of the receiver is 6m/h, and the one-dimensional nanofiber precursor is prepared. And (3) placing the obtained nanofiber precursor in a tube furnace for heating treatment under the atmosphere of mixed gas of argon with the volume concentration of 95% and hydrogen with the volume concentration of 5%, wherein the heating rate is 4 ℃/min, heating to 850 ℃ for heat treatment for 12 hours, and cooling along with the furnace to obtain the vanadium sodium phosphate composite carbon nanofiber anode material NVP/C.
2、CeO 2 The preparation method of the mesogenic material comprises the following steps: ceO is stirred under the condition of stirring 2 Concentrated sulfuric acid dispersed to 5mol/LIn the process, ce is obtained 2 (SO 4 ) 3 Stirring for 3.5h to obtain a mixed solution; pouring the mixed solution into a reaction kettle, and placing the reaction kettle into a baking oven at 180 ℃ for reacting for 20 hours; naturally cooling after the reaction is finished to obtain white precipitate, washing the white precipitate with absolute ethyl alcohol for 5 times, centrifugally separating the white precipitate, and then placing the separated product into a blast drying oven at 80 ℃ to dry for 10 hours to obtain CeO 2 A mesogenic material.
3. Conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber material (CeO) 2 Preparation procedure of @ NVP/C): NVP/C of the vanadium sodium phosphate composite carbon nanofiber anode material obtained in the step 1 and CeO prepared in the step 2 2 Mesogenic material according to 100: ball milling for 4.5 hours in a ball mill with the rotating speed of 500r/min according to the mass ratio of 0.1 to obtain precursor powder which is uniformly mixed; then placing the uniformly mixed powder into a tube furnace (under nitrogen atmosphere condition) with the temperature rising rate of 5 ℃/min for secondary heat treatment at 450 ℃ for 8 hours to obtain the conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber material (CeO) 2 @NVP/C）。
(II) application of materials
The preparation of the sodium ion battery is specifically as follows:
CeO is added with 2 The weight ratio of the @ NVP/C composite material, the binder PVDF and the conductive carbon black super p is 90:5: grinding uniformly, adding a proper amount of NMP to prepare slurry, uniformly coating the slurry on the pretreated aluminum foil, drying the aluminum foil for 1h at 80 ℃ in a forced air drying oven, and drying the aluminum foil for 12h at 120 ℃ in a vacuum drying oven; then cutting into 14mm round positive plates by a cutting machine. Sodium metal sheet with the diameter of 14mm and the thickness of 0.2mm is used as a negative electrode, 0.1mol/L sodium perchlorate/ethylene carbonate/dimethyl carbonate solution is used as electrolyte, whatman GF/F glass fiber with the diameter of 16mm is used as a diaphragm, and the CR2032 button cell is assembled in a glove box filled with high-purity argon.
(III) Performance test
And using a constant current charge-discharge mode to perform charge-discharge tests under different current densities. The test items include: the material is charged and discharged at the first round of 0.1C, the multiplying power of 1C/5C/10C/20C, the capacity retention rate of 200 th round of 1C and 500 th round of 1C in the sodium ion battery. At a discharge cut-off voltage of 2.0. 2.0V, the charge is cut offCeO prepared in this example under the condition of a stop voltage of 4.0V 2 The physicochemical properties of the @ NVP/C composite are shown in Table 1.
Example 4
The embodiment provides a conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber (TiO) 2 @NVP/C) positive electrode material, and preparation method and application thereof are as follows:
(one), a preparation method of vanadium sodium phosphate composite carbon nanofiber anode material NVP/C.
1. The preparation method of the vanadium sodium phosphate composite carbon nanofiber anode material NVP/C comprises the following steps: according to Na: v: p=3: 2:3 molar ratio of sodium carbonate (3 percent excess), vanadium pentoxide and ammonium dihydrogen phosphate, and citric acid according to mass ratio: sodium vanadium phosphate = 0.75:100, weighing citric acid, taking deionized water as a solvent, placing the citric acid on a magnetic stirrer for stirring and dissolving, and then adding polyvinylpyrrolidone, wherein the mass ratio of polyvinylpyrrolidone to sodium vanadium phosphate is 3:1, continuing stirring to form uniform electrostatic spinning solution. Extracting the electrostatic spinning solution into a 5mL injector, and installing an electrostatic spinning needle, wherein the distance between the needle and the aluminum foil is 13.5cm, and the voltage is 12KV; the speed of the electrostatic spinning is 0.15mm/min; the rotating speed of the receiver is 6m/h, and the one-dimensional nanofiber precursor is prepared. And (3) placing the obtained nanofiber precursor in a tube furnace for heating treatment under the atmosphere of mixed gas of argon with the volume concentration of 95% and hydrogen with the volume concentration of 5%, wherein the heating rate is 4 ℃/min, heating to 850 ℃ for heat treatment for 12 hours, and cooling along with the furnace to obtain the vanadium sodium phosphate composite carbon nanofiber anode material NVP/C.
2、TiO 2 The preparation method of the mesogenic material comprises the following steps: tiO is stirred 2 Dispersing into 5mol/L concentrated sulfuric acid to obtain Ti (SO 4 ) 2 Stirring for 3.5h to obtain a mixed solution; pouring the mixed solution into a reaction kettle, and placing the reaction kettle into a baking oven at 180 ℃ for reaction for 18 hours; naturally cooling after the reaction is finished to obtain white precipitate, washing the white precipitate with absolute ethyl alcohol for 5 times, centrifugally separating the white precipitate, and then placing the separated product into a blast drying oven at 80 ℃ to dry for 10 hours to obtain TiO 2 A mesogenic material.
3. Conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber material (TiO) 2 Preparation procedure of @ NVP/C): NVP/C of the vanadium sodium phosphate composite carbon nanofiber anode material obtained in the step 1 and CeO prepared in the step 2 2 Mesogenic material according to 100: ball milling for 4.5 hours in a ball mill with the rotating speed of 500r/min at the mass ratio of 0.15 to obtain precursor powder which is uniformly mixed; placing the uniformly mixed powder into a tubular furnace (nitrogen) with a heating rate of 5 ℃/min, and performing secondary heat treatment at 550 ℃ for 10 hours to obtain the conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber (TiO) 2 @ NVP/C) material.
(II) application of materials
The preparation of the sodium ion battery is specifically as follows:
TiO is mixed with 2 The weight ratio of the @ NVP/C composite material, the binder PVDF and the conductive carbon black super p is 90:5: grinding uniformly, adding a proper amount of NMP to prepare slurry, uniformly coating the slurry on the pretreated aluminum foil, drying the aluminum foil for 1h at 80 ℃ in a forced air drying oven, and drying the aluminum foil for 12h at 120 ℃ in a vacuum drying oven; then cutting into 14mm round positive plates by a cutting machine. Sodium metal sheet with the diameter of 14mm and the thickness of 0.2mm is used as a negative electrode, 0.1mol/L sodium perchlorate/ethylene carbonate/dimethyl carbonate solution is used as electrolyte, whatman GF/F glass fiber with the diameter of 16mm is used as a diaphragm, and the CR2032 button cell is assembled in a glove box filled with high-purity argon.
(III) Performance test
And using a constant current charge-discharge mode to perform charge-discharge tests under different current densities. The test items include: the material has capacity retention rate of 0.1C first circle charge and discharge, 1C/5C/10C/20C multiplying power discharge, 0.1C 200 th circle and 0.1C 500 th circle in the sodium ion battery. The TiO prepared in this example had a discharge cutoff voltage of 2.0V and a charge cutoff voltage of 4.0V 2 The physicochemical properties of the @ NVP/C composite are shown in Table 1.
Example 5
The embodiment provides a conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber (ZnO@NVP/C) positive electrode material and a preparation method and application thereof, and the conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber (ZnO@NVP/C) positive electrode material comprises the following specific steps:
(I) a preparation method of a conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber material (ZnO@NVP/C).
1. The preparation method of the vanadium sodium phosphate composite carbon nanofiber anode material NVP/C comprises the following steps: according to Na: v: p=3: 2:3 molar ratio of sodium carbonate (3 percent excess), vanadium pentoxide and ammonium dihydrogen phosphate, and citric acid according to mass ratio: sodium vanadium phosphate = 0.65:100, weighing citric acid, taking deionized water as a solvent, placing the citric acid on a magnetic stirrer for stirring and dissolving, and then adding polyvinylpyrrolidone, wherein the mass ratio of polyvinylpyrrolidone to sodium vanadium phosphate is 3:1, continuing stirring to form uniform electrostatic spinning solution. Extracting the electrostatic spinning solution into a 5mL injector, and installing an electrostatic spinning needle, wherein the distance between the needle and the aluminum foil is 13.5cm, and the voltage is 12KV; the speed of the electrostatic spinning is 0.15mm/min; the rotating speed of the receiver is 6m/h, and the one-dimensional nanofiber precursor is prepared. And (3) placing the obtained nanofiber precursor in a tube furnace for heating treatment under the atmosphere of mixed gas of argon with the volume concentration of 95% and hydrogen with the volume concentration of 5%, wherein the heating rate is 4 ℃/min, heating to 850 ℃ for heat treatment for 12 hours, and cooling along with the furnace to obtain the vanadium sodium phosphate composite carbon nanofiber anode material NVP/C.
2. The preparation method of the ZnO mesogenic material comprises the following steps: dispersing ZnO into 5mol/L concentrated sulfuric acid under stirring to obtain ZnSO 4 Stirring for 3.5h to obtain a mixed solution; pouring the mixed solution into a reaction kettle, and placing the reaction kettle into a baking oven at 180 ℃ for reaction for 18 hours; and naturally cooling after the reaction is finished to obtain a white precipitate, washing the white precipitate with absolute ethyl alcohol for 5 times, centrifugally separating the white precipitate, and then placing the separated product in a blast drying oven at 80 ℃ for drying for 10 hours to obtain the ZnO mesogenic material.
3. The preparation method of the conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber material (ZnO@NVP/C) comprises the following steps: and (2) mixing the NVP/C of the vanadium sodium phosphate composite carbon nanofiber anode material obtained in the step (1) with the ZnO mesocrystal material prepared in the step (2) according to a ratio of 100: placing the mixture in a mass ratio of 0.15 into a ball mill with the rotating speed of 500 r/min for ball milling for 4.5 hours to obtain precursor powder which is uniformly mixed; and then placing the uniformly mixed powder into a tube furnace (nitrogen) with the heating rate of 5 ℃/min for secondary heat treatment at 550 ℃ for 10 hours, thus obtaining the conductive mesogen coated carbon composite sodium vanadium phosphate nanofiber material (ZnO@NVP/C).
(II) application of materials
The preparation of the sodium ion battery is specifically as follows:
ZnO@NVP/C composite material, binder PVDF and conductive carbon black super p are mixed according to the mass ratio of 90:5: grinding uniformly, adding a proper amount of NMP to prepare slurry, uniformly coating the slurry on the pretreated aluminum foil, drying the aluminum foil for 1h at 80 ℃ in a forced air drying oven, and drying the aluminum foil for 12h at 120 ℃ in a vacuum drying oven; then cutting into 14mm round positive plates by a cutting machine. Sodium metal sheet with the diameter of 14mm and the thickness of 0.2mm is used as a negative electrode, 0.1mol/L sodium perchlorate/ethylene carbonate/dimethyl carbonate solution is used as electrolyte, whatman GF/F glass fiber with the diameter of 16mm is used as a diaphragm, and the CR2032 button cell is assembled in a glove box filled with high-purity argon.
(III) Performance test
And using a constant current charge-discharge mode to perform charge-discharge tests under different current densities. The test items include: the material is charged and discharged at the first round of 0.1C, the multiplying power of 1C/5C/10C/20C, the capacity retention rate of 200 th round of 1C and 500 th round of 1C in the sodium ion battery. The physicochemical property test results of the ZnO@NVP/C composite material prepared in the embodiment under the condition that the discharge cutoff voltage is 2.0V and the charge cutoff voltage is 4.0V are shown in Table 1.
Comparative example 1
The comparative example provides sodium vanadium phosphate NVP and a preparation method and application thereof, and the specific steps are as follows:
(I) a preparation method of sodium vanadium phosphate NVP.
The preparation method of the sodium vanadium phosphate NVP comprises the following steps: according to Na: v: p=3: 2: weighing sodium carbonate (3% excess) in a molar ratio, placing vanadium pentoxide and ammonium dihydrogen phosphate into a ball milling tank with a speed of 500r/min, ball milling for 10 hours, uniformly ball milling, placing the mixture in an atmosphere of mixed gas of argon with a volume concentration of 95% and hydrogen with a volume concentration of 5%, heating to 850 ℃ at a heating rate of 5 ℃/min, performing heat treatment for 12 hours, and cooling with a furnace to obtain the vanadium sodium phosphate NVP material with a structural characterization shown in figure 4.
(II) application of materials
Preparation of sodium ion battery: NVP material, binder PVDF and conductive carbon black super p are mixed according to the mass ratio of 90:5: grinding uniformly, adding a proper amount of NMP to prepare slurry, uniformly coating the slurry on the pretreated aluminum foil, drying the aluminum foil for 1h at 80 ℃ in a forced air drying oven, and drying the aluminum foil for 12h at 120 ℃ in a vacuum drying oven; then cutting into 14mm round positive plates by a cutting machine. Sodium metal sheet with the diameter of 14mm and the thickness of 0.2mm is used as a negative electrode, 0.1mol/L sodium perchlorate/ethylene carbonate/dimethyl carbonate solution is used as electrolyte, whatman GF/F glass fiber with the diameter of 16mm is used as a diaphragm, and the CR2032 button cell is assembled in a glove box filled with high-purity argon.
(III) Performance test
And using a constant current charge-discharge mode to perform charge-discharge tests under different current densities. The test items include: the material is charged and discharged at the first round of 0.1C, the multiplying power of 1C/5C/10C/20C, the capacity retention rate of 200 th round of 1C and 500 th round of 1C in the sodium ion battery. The physicochemical properties of the NVP material prepared in this example under the conditions of a discharge cutoff voltage of 2.0V and a charge cutoff voltage of 4.0V are shown in table 1.
Comparative example 2
The comparative example provides a sodium vanadium phosphate nanofiber positive electrode material NVP and a preparation method and application thereof, and the preparation method comprises the following steps:
(one), a preparation method of vanadium sodium phosphate nanofiber anode material NVP.
The preparation method of the vanadium sodium phosphate nanofiber anode material NVP comprises the following steps: according to Na: v: p=3: 2:3 mol ratio of sodium carbonate (3% excess), vanadium pentoxide and ammonium dihydrogen phosphate, taking deionized water as a solvent, placing the solvent on a magnetic stirrer for stirring and dissolving, and then adding polyvinylpyrrolidone, wherein the mass ratio of polyvinylpyrrolidone to sodium vanadium phosphate is 3:1, continuing stirring to form uniform electrostatic spinning solution. Extracting the electrostatic spinning solution into a 5mL injector, and installing an electrostatic spinning needle, wherein the distance between the needle and the aluminum foil is 13.5cm, and the voltage is 12KV; the speed of the electrostatic spinning is 0.15mm/min; the rotating speed of the receiver is 6m/h, and the one-dimensional nanofiber precursor is prepared. And (3) placing the obtained nanofiber precursor in a tube furnace for heating treatment under the atmosphere of mixed gas of argon with the volume concentration of 95% and hydrogen with the volume concentration of 5%, wherein the heating rate is 4 ℃/min, heating to 850 ℃ for heat treatment for 12 hours, and cooling along with the furnace to obtain the vanadium sodium phosphate nanofiber anode material NVP.
(II) application of materials
The preparation of the sodium ion battery is specifically as follows:
the method comprises the steps of (1) mixing a sodium vanadium phosphate nanofiber material, a binder PVDF and conductive carbon black super p according to a mass ratio of 90:5: grinding uniformly, adding a proper amount of NMP to prepare slurry, uniformly coating the slurry on the pretreated aluminum foil, drying the aluminum foil for 1h at 80 ℃ in a forced air drying oven, and drying the aluminum foil for 12h at 120 ℃ in a vacuum drying oven; then cutting into 14mm round positive plates by a cutting machine. Sodium metal sheet with the diameter of 14mm and the thickness of 0.2mm is used as a negative electrode, 0.1mol/L sodium perchlorate/ethylene carbonate/dimethyl carbonate solution is used as electrolyte, whatman GF/F glass fiber with the diameter of 16mm is used as a diaphragm, and the CR2032 button cell is assembled in a glove box filled with high-purity argon.
(III) Performance test
And using a constant current charge-discharge mode to perform charge-discharge tests under different current densities. The test items include: the material is charged and discharged at the first round of 0.1C, the multiplying power of 1C/5C/10C/20C, the capacity retention rate of 200 th round of 1C and 500 th round of 1C in the sodium ion battery. The physicochemical property test results of the sodium vanadium phosphate nanofiber material prepared in this example under the condition that the discharge cutoff voltage is 2.0V and the charge cutoff voltage is 4.0V are shown in table 1.
Comparative example 3
The comparative example provides a vanadium sodium phosphate composite carbon nanofiber positive electrode material NVP/C and a preparation method and application thereof, and the NVP/C is specifically as follows:
(one), a preparation method of vanadium sodium phosphate composite carbon nanofiber anode material NVP/C.
According to Na: v: p=3: 2:3 molar ratio of sodium carbonate (3 percent excess), vanadium pentoxide and ammonium dihydrogen phosphate, and citric acid according to mass ratio: sodium vanadium phosphate = 0.65:100, weighing citric acid, taking deionized water as a solvent, placing the citric acid on a magnetic stirrer for stirring and dissolving, and then adding a high-molecular polymer: sodium vanadium phosphate mass ratio = 3:1, and continuously stirring to form uniform electrostatic spinning solution. Extracting the electrostatic spinning solution into a 5mL injector, and installing an electrostatic spinning needle, wherein the distance between the needle and the aluminum foil is 13.5cm, and the voltage is 12KV; the speed of the electrostatic spinning is 0.15mm/min; the rotating speed of the receiver is 6m/h, and the one-dimensional nanofiber precursor is prepared. And (3) placing the obtained nanofiber precursor in a tube furnace for heating treatment under the atmosphere of mixed gas of argon with the volume concentration of 95% and hydrogen with the volume concentration of 5%, wherein the heating rate is 4 ℃/min, heating to 850 ℃ for heat treatment for 12 hours, and cooling along with the furnace to obtain the vanadium sodium phosphate composite carbon nanofiber anode material NVP/C.
(II) application of materials
The preparation of the sodium ion battery is specifically as follows:
NVP/C composite material, binder PVDF and conductive carbon black super p are mixed according to the mass ratio of 90:5: grinding uniformly, adding a proper amount of NMP to prepare slurry, uniformly coating the slurry on the pretreated aluminum foil, drying the aluminum foil for 1h at 80 ℃ in a forced air drying oven, and drying the aluminum foil for 12h at 120 ℃ in a vacuum drying oven; then cutting into 14mm round positive plates by a cutting machine. Sodium metal sheet with the diameter of 14mm and the thickness of 0.2mm is used as a negative electrode, 0.1mol/L sodium perchlorate/ethylene carbonate/dimethyl carbonate solution is used as electrolyte, whatman GF/F glass fiber with the diameter of 16mm is used as a diaphragm, and the CR2032 button cell is assembled in a glove box filled with high-purity argon.
(III) Performance test
And using a constant current charge-discharge mode to perform charge-discharge tests under different current densities. The test items include: the material has capacity retention rate of 0.1C first circle charge and discharge, 1C/5C/10C/20C multiplying power discharge, 0.1C 200 th circle and 0.1C 500 th circle in the sodium ion battery. The physicochemical properties of the NVP/C composite material prepared in this example under the conditions of a discharge cutoff voltage of 2.0V and a charge cutoff voltage of 4.0V are shown in Table 1.
Comparative example 4
The comparative example provides a sodium vanadium phosphate nanofiber anode material NVP/C and a preparation method and application thereof, and the preparation method comprises the following steps:
(one), a preparation method of vanadium sodium phosphate nanofiber anode material NVP/C.
1. According to Na: v: p=3: 2:3 mol ratio of sodium carbonate (3% excess), vanadium pentoxide and ammonium dihydrogen phosphate, taking deionized water as a solvent, placing the solvent on a magnetic stirrer for stirring and dissolving, and then adding polyvinylpyrrolidone, wherein the mass ratio of polyvinylpyrrolidone to sodium vanadium phosphate is 3:1, continuing stirring to form uniform electrostatic spinning solution. Extracting the electrostatic spinning solution into a 5mL injector, and installing an electrostatic spinning needle, wherein the distance between the needle and the aluminum foil is 13.5cm, and the voltage is 12KV; the speed of the electrostatic spinning is 0.15mm/min; the rotating speed of the receiver is 6m/h, and the one-dimensional nanofiber precursor is prepared. And (3) placing the obtained nanofiber precursor into a tubular furnace with the heating rate of 4 ℃/min and the atmosphere of 95% argon and 5% hydrogen, and carrying out heat treatment at 850 ℃ for 12 hours, and cooling along with the furnace to obtain the vanadium sodium phosphate nanofiber anode material NVP.
2. TiO is stirred under the condition of material stirring 2 Dispersing into 5mol/L concentrated sulfuric acid to obtain Ce 2 (SO 4 ) 3 Stirring for 3.5h to obtain a mixed solution; pouring the mixed solution into a reaction kettle, and placing the reaction kettle into a baking oven at 180 ℃ for reaction for 18 hours; naturally cooling after the reaction is finished to obtain white precipitate, washing the white precipitate with absolute ethyl alcohol for 5 times, centrifugally separating the white precipitate, and then placing the separated product into a blast drying oven at 80 ℃ to dry for 10 hours to obtain TiO 2 A mesogenic material.
3. NVP (NVP) serving as a positive electrode material of the sodium vanadium phosphate nanofiber obtained in the step 1 and TiO prepared in the step 2 are mixed 2 Mesogenic material according to 100: placing the mixture in a mass ratio of 0.15 into a ball mill with the rotating speed of 500 r/min for ball milling for 4.5 hours to obtain precursor powder which is uniformly mixed; placing the uniformly mixed powder into a tubular furnace (nitrogen) with a heating rate of 5 ℃/min, and performing secondary heat treatment at 550 ℃ for 10 hours to obtain the conductive mesogen coated sodium vanadium phosphate nanofiber (TiO) 2 @ NVP) material.
(II) application of materials
The preparation of the sodium ion battery is specifically as follows:
TiO is mixed with 2 The weight ratio of the@NVP composite material, the binder PVDF and the conductive carbon black super p is 90:5:5, grinding uniformly, wherein the grinding is carried out,adding a proper amount of NMP to prepare slurry, uniformly coating the slurry on the pretreated aluminum foil, drying the aluminum foil for 1h at 80 ℃ in a blast drying oven, and drying the aluminum foil for 12h at 120 ℃ in a vacuum drying oven; then cutting into 14mm round positive plates by a cutting machine. Sodium metal sheet with the diameter of 14mm and the thickness of 0.2mm is used as a negative electrode, 0.1mol/L sodium perchlorate/ethylene carbonate/dimethyl carbonate solution is used as electrolyte, whatman GF/F glass fiber with the diameter of 16mm is used as a diaphragm, and the CR2032 button cell is assembled in a glove box filled with high-purity argon.
(III) Performance test
And using a constant current charge-discharge mode to perform charge-discharge tests under different current densities. The test items include: the material has capacity retention rate of 0.1C first circle charge and discharge, 1C/5C/10C/20C multiplying power discharge, 0.1C 200 th circle and 0.1C 500 th circle in the sodium ion battery. The TiO prepared in this comparative example had a discharge cutoff voltage of 2.0V and a charge cutoff voltage of 4.0V 2 The physicochemical properties of the @ NVP composite are shown in Table 1.
Table 1 electrochemical performance tables of examples 1 to 3 and comparative examples 1 to 4
Figure SMS_1
Note that: "/" indicates that the charge-discharge curve is abnormal and charge-discharge cannot be performed.
As can be seen from Table 1, (1) and examples 1 to 3, ceO with different contents was used in the case of the same type of the host material 2 The discharging capacity of the material is lower when the coating content is higher, but the rate performance and the cycle stability are better; the lower the coating content, the higher the discharge capacity of the material, but the magnification and cycle performance of the material can be affected. Examples 1 to 5 compared with comparative example 1, the 0.1C first-turn discharge capacity is slightly reduced due to the existence of the mesogenic coating layer and carbon, but the 1C discharge capacity and the 1C 200-turn capacity retention rate are both remarkably improved, and the material of comparative example 1 cannot even satisfy the charge and discharge under 5C multiplying power and can not complete the charge and discharge cycle of 500 turns, thus indicating that the mesogenic material prepared by the invention coats sodium vanadium phosphate carbon complex The composite nanofiber can effectively improve the multiplying power performance and the cycle performance of the vanadium sodium phosphate anode material.
(2) Example 4 is different from comparative example 4 in that whether or not the sodium vanadium phosphate is carbon-compounded, and the mesogen coating method of the sodium vanadium phosphate carbon composite nanofiber is adopted in the example 4 in combination with the data in table 1, because carbon exists in a part of reversible capacity of the sacrificial material, the rate performance and the capacity retention rate of the material, particularly the high rate discharge performance are improved. Compared with comparative example 3, the difference is that whether a mesogenic material coating layer exists or not, and the data in the table shows that after the mesogenic material coats the vanadium sodium phosphate carbon composite nanofiber, the multiplying power performance and the capacity retention rate of the material are greatly improved, which shows that the coating of the mesogenic material can effectively inhibit the structural collapse caused by the material in the high-multiplying power charge-discharge process, thereby stabilizing the structure of the material and improving the cycle stability and the high-multiplying power discharge characteristic of the material.
(3) In comparison with the amorphous sodium vanadium phosphate material synthesized by the common solid phase method in comparative example 1, compared with the sodium vanadium phosphate nanofiber synthesized by adopting electrostatic spinning in comparative example 2, the amorphous sodium vanadium phosphate material has reduced capacity under the condition of 1C rate discharge, but cannot meet the high rate discharge performance of the material. This shows that the nano-scale of sodium vanadium phosphate can improve the electrochemical performance of the material to a certain extent. Comparative example 3 is a vanadium sodium phosphate carbon composite nanofiber NVP/C prepared by the method of the invention, and compared with comparative example 2, the composite of the carbon material is increased, so that the rate performance and the capacity retention rate of the material are improved to a certain extent, but the material is still not ideal under the condition of high-rate discharge. Comparative example 4 is a mesogen coated sodium vanadium phosphate nanofiber M 2 O x The NVP lacks the compounding of carbon materials and improves the rate discharge performance of the materials, but the method has limited improvement on high rate discharge and capacity retention rate as the independent carbon compounding.
In conclusion, the invention adopts the mesogen coated vanadium sodium phosphate carbon composite nanofiber M 2 O x The method of the NVP/C material improves the electronic conductivity and the structural stability of the material by using the package of the mesogenic material and the synergistic vanadium sodium phosphate carbon composite nano fiber,greatly improves the high-rate discharge performance and the cycle stability of the material.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations and modifications of the present invention will be apparent to those of ordinary skill in the art in light of the foregoing description. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.

Claims (10)

1. The preparation method of the positive electrode material is characterized by comprising the following steps of:
mixing a sodium source, a vanadium source, a phosphorus source, a high polymer, a carbon source and a solvent to obtain an electrostatic spinning solution, carrying out electrostatic spinning to obtain a precursor of nanofiber, and carrying out primary heat treatment to obtain a vanadium sodium phosphate composite carbon nanofiber material;
Dispersing salt or oxide containing M into an acid solution, reacting the obtained mixed solution at 100-200 ℃, and then separating solid from liquid of the reaction solution to obtain a solid phase, namely M 2 O x A mesogenic material;
combining the sodium vanadium phosphate composite carbon nanofiber material with the M 2 O x The mesogenic materials are mixed and subjected to secondary heat treatment to form M 2 O x The mesogenic coating layer is used for obtaining the anode material;
where M is one or more of Zn, ce, ti, cu, fe, W, pb and Cd, and x is the valence of M.
2. The preparation method of claim 1, wherein the mass ratio of the carbon source to the sodium vanadium phosphate in the sodium vanadium phosphate composite carbon nanofiber material is 0.5-1.5: 100, wherein the mass ratio of the high molecular polymer to the sodium vanadium phosphate in the sodium vanadium phosphate composite carbon nanofiber material is 2-5: 1.
3. the method according to claim 1, wherein the conditions of electrospinning: the voltage is 10 KV-15 KV, and the distance between a filament outlet and a receiver in the electrostatic spinning device is 12 cm-20 cm; the spinning speed is 0.1-0.5 mm/min, and the rotating speed of the receiver is 4-8 m/h;
the conditions of the primary heat treatment: the temperature of the heating sintering is 600-1000 ℃, the time of the heating sintering is 4-20 hours, the temperature rising rate of the heating sintering is 1-10 ℃/min, and the gas atmosphere of the heating sintering comprises the mixed gas of argon and hydrogen.
4. The method according to claim 1, wherein the vanadium sodium phosphate composite carbon nanofiber material and the M 2 O x In the step of mixing the mesogenic material, the vanadium sodium phosphate composite carbon nanofiber material and the M 2 O x The mass ratio of the mesogenic material is 100:0.1 to 0.4.
5. The method of claim 1, wherein the acid in the acid solution is selected from sulfuric acid and/or nitric acid; the concentration of the acid solution is 15-35 wt%.
6. The method according to claim 1, wherein the conditions of the secondary heat treatment: the sintering temperature is 200-550 ℃, the sintering time is 3-10 hours, the heating rate is 1-10 ℃/min, and the gas in the heated and sintered gas atmosphere is one or more of helium, argon and nitrogen;
the vanadium sodium phosphate composite carbon nanofiber material and the M 2 O x In the step of mixing the mesogenic materials, a ball milling method is selected as a mixing method, the ball milling speed is 250 r/min-750 r/min, and the ball milling time is 1 h-6 h.
7. The positive electrode material is characterized by comprising a vanadium sodium phosphate composite carbon nanofiber material and a conductive mesogen wrapping layer wrapping the surface of the vanadium sodium phosphate composite carbon nanofiber material.
8. The positive electrode material according to claim 7The conductive mesogenic coating is characterized in that the conductive mesogenic coating comprises a conductive mesogenic material, and the molecular formula of the conductive mesogenic material is M 2 O x The method comprises the steps of carrying out a first treatment on the surface of the Where M is one or more of Zn, ce, ti, cu, fe, W, pb and Cd, and x is the valence of M.
9. A positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer provided on at least one side of the positive electrode current collector, the positive electrode active material layer comprising the positive electrode material obtained by the production method according to any one of claims 1 to 6, the positive electrode material according to claim 7 or 8.
10. A sodium ion battery comprising the positive electrode sheet of claim 9.
CN202310488820.9A 2023-05-04 2023-05-04 Positive electrode material and preparation method and application thereof Pending CN116190666A (en)

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