CN115036486A - Polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material and preparation method and application thereof - Google Patents

Polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material and preparation method and application thereof Download PDF

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CN115036486A
CN115036486A CN202210733410.1A CN202210733410A CN115036486A CN 115036486 A CN115036486 A CN 115036486A CN 202210733410 A CN202210733410 A CN 202210733410A CN 115036486 A CN115036486 A CN 115036486A
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polyvinylpyrrolidone
sodium
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electrode material
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陈彦俊
李家豪
田真
王延忠
郭丽
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North University of China
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    • Y02E60/10—Energy storage using batteries

Abstract

The invention belongs to the technical field of sodium ion batteries, and provides a polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material, and a preparation method and application thereof, aiming at solving the problems of low intrinsic conductivity, low ionic conductivity, low energy density and the like of vanadium sodium phosphate. The composite anode material is obtained by using ammonium metavanadate and sodium dihydrogen phosphate as raw materials, citric acid as a chelating agent, polyvinylpyrrolidone as a structure directing agent and an additional carbon source through a solution gel method, wherein the material is irregular Na 3 V 2 (PO 4 ) 3 And layersNa (b) of 3 V 3 (PO 4 ) 4 The two-phase composite material is formed, and a nitrogen-doped carbon coating layer formed after sintering polyvinylpyrrolidone is arranged outside the two-phase composite material. Two stable high-voltage platforms are arranged at the positions of 3.4V and 3.9V respectively, so that the overall energy density of the material is greatly improved. The nitrogen-doped carbon coating has more defects, allows ions and electrons to move rapidly, and improves the intrinsic electronic conductivity and the ionic conductivity of the material.

Description

Polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material and preparation method and application thereof
Technical Field
The invention belongs to the technical field of positive electrode materials of sodium-ion batteries, and particularly relates to a polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material as well as a preparation method and an application thereof.
Background
With the development of new energy technologies and the explosive growth of portable intelligent devices, the demand for energy storage batteries is rapidly increasing around the world. Although lithium ion batteries are widely used due to their excellent energy storage properties, their lack of resources and high cost limit their applications. Since sodium and lithium have similar physicochemical properties in the same main group element phase, sodium ion batteries are considered as one of the most promising replacements for lithium ion batteries.
Na 3 V 2 (PO 4 ) 3 Is an ideal positive electrode material of the sodium ion battery and has an open and stable three-dimensional ion fast channel. Utilizing the NASCION framework and two extractable sodium ions, Na 3 V 2 (PO 4 ) 3 The theoretical reversible specific capacity of the material reaches 117.6 mAh g −1 . However, due to Na 3 V 2 (PO 4 ) 3 The intrinsic conductivity and ionic conductivity of the material are low, and in practical application, the energy density and specific discharge capacity of the material are far lower than theoretical values, which greatly limits the commercial application of the material.
Na regulation by adding special carbon source 3 V 2 (PO 4 ) 3 Is a promising approach to improve its performance. The carbon coating layer is beneficial to the rapid migration of electrons on the surface of the material, so that the intrinsic conductivity of the material is improved. However, an excessively thick carbon coating layer can hinder the ion diffusion process of sodium ions in the charging and discharging processes, and the reversible specific capacity of the material is reduced. In addition, the method can be used for producing a composite materialWith the increase of the carbon coating layers, the proportion of the carbon layer in the whole electrode material is increased, and the specific discharge capacity and the energy density of the vanadium sodium phosphate carbon composite anode material are reduced.
Disclosure of Invention
The invention aims to solve the problem of Na 3 V 2 (PO 4 ) 3 The problems of low intrinsic conductivity, low energy density and the like of the composite cathode material, and provides a polyvinylpyrrolidone-induced vanadium sodium phosphate composite cathode material, and a preparation method and application thereof. Inducing the precursor solution to synthesize irregular Na by the structure-oriented action of polyvinylpyrrolidone in the synthesis process 3 V 2 (PO 4 ) 3 And layered Na 3 V 3 (PO 4 ) 4 The energy density of the material is greatly improved. Meanwhile, a nitrogen-doped carbon coating layer is formed after the polyvinylpyrrolidone is carbonized, so that the intrinsic conductivity of the material is improved, the ionic conductivity of the material is improved, and the material shows excellent electrochemical performance. The electrode material is loaded on a 2016 type button cell, shows excellent cycle stability and large-rate long-cycle performance, and can be considered as a sodium ion battery anode material with great prospect.
The invention is realized by the following technical scheme: a polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material takes ammonium metavanadate and sodium dihydrogen phosphate as raw materials, citric acid as a chelating agent, polyvinylpyrrolidone as a structure directing agent and an additional carbon source, and the mass ratio of the mass of the polyvinylpyrrolidone to the mass of the sodium dihydrogen phosphate is x:2.3684, wherein x =2, 3 or 4; the polyvinylpyrrolidone-induced vanadium sodium phosphate composite anode material is prepared by a one-step method, and is irregular Na 3 V 2 (PO 4 ) 3 And layered Na 3 V 3 (PO 4 ) 4 The two-phase composite material is formed, and a nitrogen-doped carbon coating layer formed after sintering polyvinylpyrrolidone is arranged outside the two-phase composite material.
The method for preparing the polyvinylpyrrolidone-induced vanadium sodium phosphate composite anode material comprises the following specific steps:
(1) taking sodium dihydrogen phosphate, ammonium metavanadate and citric acid with the molar ratio of 82.21:5.46:1, adding the sodium dihydrogen phosphate and the ammonium metavanadate into 100mL of deionized water, heating to 70 ℃ at constant temperature, continuously stirring, and reacting to form a yellow transparent solution of the sodium vanadium phosphate; slowly adding citric acid into the yellow transparent solution, and finally stabilizing the color to be blue;
(2) slowly adding polyvinylpyrrolidone into the blue solution prepared in the step (1) until the polyvinylpyrrolidone is completely dissolved; wherein the mass ratio of the polyvinylpyrrolidone to the sodium dihydrogen phosphate is x:2.3684 (x =2, 3 or 4), and stirring at constant temperature until the precursor solution is concentrated into 20ml of viscous colloid;
(3) placing the viscous colloid prepared in the step (2) in a forced air oven, and drying for 12h at 80 ℃ by forced air drying to obtain a precursor;
(4) and (4) presintering the precursor obtained in the step (3) at 450 ℃ for 4h in the atmosphere of nitrogen, and then, performing final burning at 700 ℃ for 6h to obtain a final product.
The invention also provides application of the polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material in a sodium ion battery. The specific method comprises the following steps: (1) preparing a positive electrode material: the polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material is used as an active substance of a positive electrode material, and the ratio of the active substance to the negative electrode material is as follows (7: 2: 1, mixing the conductive filler acetylene black and the adhesive polyvinylidene fluoride in 1.4 mL of N-methylpyrrolidone NMP solvent; placing the mixture in a ball milling tank, performing one-way ball milling for four hours to obtain slurry, coating the slurry on a carbon-coated aluminum foil, performing forced air drying at 45 ℃ for four hours, and performing vacuum drying at 120 ℃ for 6 hours to obtain a positive electrode material;
(2) assembling the battery: taking the anode material prepared in the step (1) as an anode, metal sodium as a cathode, a ceramic Celgard diaphragm as a diaphragm, and NaClO as electrolyte 4 + EC/DEC +5% FEC; wherein, NaClO 4 EC, DEC and FEC denote sodium perchlorate, ethylene carbonate, diethyl carbonate and fluoroethylene carbonate, respectively; 1M NaClO 4 Dissolving the mixture in an EC/DEC system with the volume ratio of 1:1, adding 5 wt% of FEC to prepare an electrolyte, and assembling the electrolyte into a 2016 type button cell.
The invention synthesizes the random Na by one step through a sol-gel method by adding large dosage of polyvinylpyrrolidone as an additional carbon source and a structure directing agent 3 V 2 (PO 4 ) 3 And layered Na 3 V 3 (PO 4 ) 4 The two-phase composite material greatly improves the energy density of the material. In particular, PVP controls the two-phase formation of the precursor solution by two mechanisms. In one aspect, the PVP forms a cross-linked network in the precursor solution, and the overlapping cross-linked network induces the precursor to form a layered Na 3 V 3 (PO 4 ) 4 (ii) a On the other hand, O and N atoms in PVP molecules can provide lone electron pairs to form coordination complexes in aqueous solution. Therefore, PVP is used as a chelating agent in the precursor solution to increase the steric hindrance between the precursor particles, and the PVP is agglomerated after sintering to generate irregular Na 3 V 2 (PO 4 ) 3 . In addition, the nitrogen atom on the five-membered ring in PVP is reduced. Thus, PVP also acts as a reducing agent in the precursor solution, allowing the reduction reaction to proceed from V 5+ To V 3+ Faster and more adequate.
It is worth noting that the polyvinylpyrrolidone forms a nitrogen-doped carbon coating layer after sintering, and the nitrogen-doped carbon forms a highly graphitized carbon coating layer, which is beneficial to the rapid transmission of electrons. This may be attributed to the partial ordering of the carbon nanoparticles by clusters and radicals formed upon thermal decomposition of PVP. In addition, because the nitrogen-doped carbon layer generates additional defects and active sites, the carbon layer formed after sintering the polyvinylpyrrolidone can also allow sodium ions to rapidly pass through, so that the intrinsic electronic conductivity and the ionic conductivity are simultaneously improved.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. the invention utilizes polyvinylpyrrolidone as an additional carbon source and a structure directing agent to prepare Na by a one-step method 3 V 2 (PO 4 ) 3 /Na 3 V 3 (PO 4 ) 4 The two-phase composite material has simple preparation steps and low raw material price.
2. The sintered polyvinylpyrrolidone forms a nitrogen-doped carbon coating layer, so that the intrinsic conductivity and the ionic conductivity of the material are improved, and the material has excellent electrochemical performance.
3. The material prepared by the invention has two stable high-voltage platforms which are respectively positioned at 3.4V and 3.9V.
4. The material prepared by the invention has extremely high energy density, excellent electrochemical performance and obvious practical value.
Drawings
FIG. 1 is a TEM image of PVP-induced sodium vanadium phosphate composite positive electrode material prepared in example 2, from which random Na is observed 3 V 2 (PO 4 ) 3 Of layered Na 3 V 3 (PO 4 ) 4 And a carbon coating layer formed after sintering polyvinylpyrrolidone;
FIG. 2 is a TEM image of the PVP-induced sodium vanadium phosphate composite cathode material prepared in example 2, and it can be seen from the TEM image that the particle size of the two-phase material is relatively low and the two-phase material is uniformly dispersed, which is beneficial to improving the electron conduction between particles;
fig. 3 is an XRD spectrum of the polyvinylpyrrolidone-induced sodium vanadium phosphate composite positive electrode material prepared in example 2, which shows: the two-phase substances of the vanadium phosphate sodium composite anode material induced by polyvinylpyrrolidone are respectively Na in random shapes 3 V 2 (PO 4 ) 3 And layered Na 3 V 3 (PO 4 ) 4 ；
Fig. 4 is a Raman spectrum of the polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material prepared in example 2, and the Raman spectrum shows that: the nitrogen-doped carbon coating layer after the carbonization of the polyvinylpyrrolidone has higher disorder degree;
fig. 5 is a graph of constant current first-loop charge and discharge curves measured when 2016 type coin cells were assembled in examples 1, 2, 3 and 4, and the current density was 0.1C;
FIG. 6 is a graph comparing rate performance measured at different current densities for 2016 type coin cells assembled from examples 1, 2, 3, and 4;
fig. 7 is the average energy density at 200 cycles at 0.1C current density for example 2, comparative example 4, when assembled as a 2016 type coin cell;
fig. 8 is a graph comparing the specific discharge capacity at 0.1C current density for 200 cycles of example 2, comparative example 4, when assembled into a 2016 type coin cell;
fig. 9 is an EIS curve at 3.4V for the polyvinylpyrrolidone-induced sodium vanadium phosphate composite positive electrode material prepared in example 2 when assembled as a 2016 type coin cell.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments; all other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs and the disclosures and references cited therein and the materials cited therein are hereby incorporated by reference.
Those skilled in the art will recognize that equivalents to the specific embodiments described, as may be learned by routine experimentation, are intended to be encompassed by the present application.
The experimental procedures in the following examples are all conventional ones unless otherwise specified. The instruments used in the following examples are, unless otherwise specified, laboratory-standard instruments; the experimental materials used in the following examples were purchased from a conventional biochemical reagent store unless otherwise specified.
Example 1: preparing a polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material (PVP-1):
1.5395g of ammonium metavanadate and 2.3684g of sodium dihydrogen phosphate are dissolved in 100mL of deionized water, heated to 70 ℃ in a water bath, and continuously stirred to react to form a yellow and transparent solution of sodium vanadium phosphate. 0.5077g of citric acid were slowly added to the clear solution, and the mixture was stirred at a constant temperature of 70 ℃ for 4 hours until the solution became dark blue. 2g of polyvinylpyrrolidone was slowly added and stirring was continued at 70 ℃ until the polyvinylpyrrolidone was completely dissolved. Stirring was carried out at constant temperature until the precursor solution became 20ml of viscous gel. Drying in a blast oven at 80 deg.C for 12 hr to obtain precursor; the obtained precursor is presintered for 4 hours at 450 ℃ in the atmosphere of nitrogen, and then is finally calcined for 6 hours at 700 ℃ to obtain the final product.
Using the positive electrode material prepared in this example as an active material, the ratio of 7: 2: 1 was mixed with a conductive filler (acetylene black) and a binder (polyvinylidene fluoride) in 1.4 mL of N-methylpyrrolidone (NMP) solvent. And (3) placing the mixture in a ball milling tank, performing unidirectional ball milling for four hours to obtain slurry, and coating the slurry on the carbon-coated aluminum foil. After being dried by air blast for four hours at the temperature of 45 ℃, vacuum drying is carried out for 6 hours at the temperature of 120 ℃. The electrolyte is prepared from NaClO, metal sodium, ceramic Celgard diaphragm and electrolyte 4 + EC/DEC +5% FEC; wherein, NaClO 4 EC, DEC and FEC denote sodium perchlorate, ethylene carbonate, diethyl carbonate and fluoroethylene carbonate, respectively; 1M NaClO 4 Dissolved in an EC/DEC system in a volume ratio of 1:1, with 5 wt% FEC being added. The cells were assembled in a vacuum glove box to give a 2016 type button cell.
And carrying out constant-current charge and discharge test on the assembled button cell at room temperature within the voltage range of 2.3-4.1V. Specifically, the first-turn charge-discharge curve is shown in fig. 5, and the specific discharge capacity under different multiplying power is shown in fig. 6.
The material is detected to be used as the positive electrode material of the sodium-ion battery. Electrochemical tests show that the specific discharge capacity of the material under 0.1C can reach 71.3mAh g -1 . In addition, it exhibits two high discharge plateaus at 3.4V and 3.9V. The battery cycle rate shows that under the condition of 10C high rate, the specific discharge capacity of the material can still be kept at 56.7mAh g -1 And when the discharge rate is increased to 1C, the material can still be quickly increased to 79.1mAh g -1 Specific discharge capacity of (2).
Example 2: preparing a polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material (PVP-2): the amount of polyvinylpyrrolidone added was 3g, and the other procedures were the same as those described in example 1.
In order to better show the characteristics, the TEM images of the cathode material prepared in this example are shown in fig. 1 and fig. 2, and it can be seen from the images that the particle size of the two-phase material is lower and the two-phase material is uniformly dispersed, which is beneficial to improving the electron conduction among the particles; the XRD spectrum is shown in figure 3, and shows that: the two-phase substances of the vanadium phosphate sodium composite anode material induced by polyvinylpyrrolidone are respectively Na in random shapes 3 V 2 (PO 4 ) 3 And layered Na 3 V 3 (PO 4 ) 4 (ii) a The Raman spectrum is shown in FIG. 3, and the Raman spectrum surface is as follows: the nitrogen-doped carbon coating layer after the carbonization of the polyvinylpyrrolidone has higher disorder degree.
The different two-phase compositions of the material are clearly shown in the TEM images. Comparing the characteristic peaks of the two-phase substances in the XRD spectrogram, the two-phase substances of the vinylpyrrolidone-induced vanadium sodium phosphate composite anode material can be determined to be respectively irregular Na 3 V 2 (PO 4 ) 3 And layered Na 3 V 3 (PO 4 ) 4 . The high disorder of the Raman spectrum indicates a high defect level of the nitrogen-doped carbon coating, which facilitates rapid diffusion of sodium ions.
The positive electrode material prepared in this example was used as an active material, and assembled into a 2016 type coin cell in a vacuum glove box. The rest of the preparation method is the same as the method described in example 1.
The button cell assembled by the battery is subjected to constant current charge and discharge test in the voltage range of 2.3-4.1V at room temperature and is subjected to constant current charge and discharge test in the voltage range of 0.1-0.5mVs -1 The current density was 0.1C, as measured by cyclic voltammetry over the range of scan rates. Specifically, a first-turn charge-discharge curve is shown in fig. 5, and multiplying power performance under different multiplying powers is shown in fig. 6; the average energy density for 200 cycles at 0.1C current density is shown in fig. 7, and the specific discharge capacity is shown in fig. 8. EIS test curve at 3.4V is shown in FIG. 9As shown.
The material is detected to be used as the positive electrode material of the sodium-ion battery. Electrochemical tests show that the specific discharge capacity of the material under 0.1C can reach 119.2mAh g -1 . In addition, it exhibits two high discharge plateaus at 3.4V and 3.9V. The battery cycle rate shows that the specific discharge capacity of the material can be kept at 86.8mAh g under the condition of 10C high rate -1 And when the discharge rate is increased to 1C, the material can still be quickly increased to 101.2mAh g -1 Indicating that the material exhibits excellent rate performance when loaded in a 2016 type button cell. Furthermore, the average energy density of 200 cycles at a current density of 0.1C was as high as 408.1 Wh kg -1 This can be attributed to Na 3 V 3 (PO 4 ) 4 Is performed. Due to Na 3 V 3 (PO 4 ) 4 This layered material is present, resulting in a stable voltage plateau at 3.9V, which provides capacity while also significantly increasing the energy density of the material. The battery cycle test shows that after the material is cycled for 200 circles under the current density of 0.1C, the specific discharge capacity of the material is still as high as 102.6mAh g -1 This indicates that the material has excellent cycling stability.
In addition, the EIS curve at 3.4V characterizes the electronic and ionic conductivities of PVP-2. The high-frequency area is semicircular, and the low-frequency area is a straight line and respectively corresponds to the transfer resistance and the Warburg impedance of the material. The transfer resistance of this material was only 131.0 Ω, showing its excellent electronic conductivity. This may be attributed to the highly ordered nitrogen-doped carbon layer transformed by PVP after sintering, which may allow high-speed transport of electrons at the surface of the material. In addition, the diffusion coefficient of sodium ions is in a negative correlation with the slope of the Warburg impedance portion. According to calculation, the diffusion coefficient of sodium ions is as high as 2.00 multiplied by 10 -15 cm 2 s -1 . This is because the nitrogen-doped carbon layer after PVP carbonization has large defects, allowing rapid diffusion of sodium ions. The low slope of the Warburg impedance portion of PVP-2 reflects its extremely high sodium ion diffusion coefficient, indicating that the material has excellent ionic conductivity. With normal Na 3 V 2 (PO 4 ) 3 Compared with the prior art, the prepared polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material has excellent electronic conductivity and ionic conductivity.
Example 3: preparing a polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material (PVP-3): the amount of polyvinylpyrrolidone added was 4g, and the rest of the method was the same as that described in example 1.
The positive electrode material prepared in this example was used as an active material, and assembled into a 2016 type coin cell in a vacuum glove box. The rest of the procedure was the same as described in example 1.
And carrying out constant-current charge and discharge test on the assembled button cell at room temperature within the voltage range of 2.3-4.1V. Specifically, the first-circle charge-discharge curve is shown in fig. 5, and the specific discharge capacity under different multiplying factors is shown in fig. 6.
The material is detected to be used as the positive electrode material of the sodium-ion battery. Electrochemical tests show that the specific discharge capacity of the material under 0.1C can reach 75.8mAh g -1 . In addition, it exhibits two high discharge plateaus at 3.4V and 3.9V. The battery cycle rate shows that under the condition of 10C high rate, the specific discharge capacity of the material can still be kept at 58.4mAh g -1 And when the discharge rate is increased to 1C, the material can still be quickly increased to 78.6mAh g -1 Specific discharge capacity of (2).
Example 4: na prepared according to the method of the invention 3 V 2 (PO 4 ) 3 ：
1.5395g of ammonium metavanadate and 2.3684g of sodium dihydrogen phosphate were dissolved in 100mL of deionized water, heated to 70 ℃ in a water bath, and stirred continuously to form a clear yellow solution. 0.5077g of citric acid was slowly added to the clear solution, and stirred at constant temperature of 70 ℃ for 4 hours until the solution became dark blue. Stirring was carried out at constant temperature until the precursor solution became 20ml of viscous gel. Drying in a blast oven at 80 deg.C for 12 hr; the obtained precursor is presintered for four hours at 450 ℃ in the nitrogen atmosphere and finally burned for 6 hours at 700 ℃ to obtain the final product.
The positive electrode material prepared in this example was used as an active material, and assembled into a 2016 type coin cell in a vacuum glove box. The rest of the procedure was the same as described in example 1.
And carrying out constant-current charge and discharge test on the assembled button cell at room temperature within the voltage range of 2.3-4.1V. Specifically, the first-circle charge-discharge curve is shown in fig. 5, and the specific discharge capacity under different multiplying factors is shown in fig. 6. The EIS test plot at 3.4V is shown in FIG. 9.
The material is detected to be used as the anode material of the sodium-ion battery. Electrochemical tests show that the specific discharge capacity of the material under 0.1C can reach 63.7mAh g -1 . It has only one stable discharge plateau at 3.4V. The battery cycle rate shows that under the condition of 10C high rate, the specific discharge capacity of the material can still be kept at 49.7mAh g -1 And when the discharge rate is increased to 1C, the material can still be quickly increased to 63.1mAh g -1 Specific discharge capacity of (2). Under 3.4V, the high-frequency area of the EIS curve is semicircular, and the low-frequency area is a straight line and respectively corresponds to the transfer resistance and the Warburg impedance of the material. The material has transfer resistance as high as 750.1 Ω, relatively high Warburg impedance part slope and sodium ion diffusion coefficient of only 9.60 × 10 -16 cm 2 s -1 . The electronic and ionic conductivities of the material proved to be relatively low.
The above examples illustrate: the invention uses a convenient solution gel method and takes polyvinylpyrrolidone as a structure directing agent to synthesize the vanadium sodium phosphate composite anode material by one step. The product of the invention contains Na in random shape 3 V 2 (PO 4 ) 3 And layered Na 3 V 3 (PO 4 ) 4 A two-phase material. The composite material has two stable high voltage platforms, located at 3.4V and 3.9V, respectively. In addition, the polyvinylpyrrolidone forms a nitrogen-doped carbon coating layer after sintering, has more defects, and can allow ions and electrons to rapidly move, so that the intrinsic conductivity and the ionic conductivity of the material are improved. The test shows that the two high-voltage platforms of the invention have excellent electrochemical performance, high energy density and high rate stability. Meanwhile, the material is simple to prepare, low in cost and expected to be popularized in the industry.
Finally, it should be noted that: although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (4)

1. A polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material is characterized in that: the composite cathode material takes ammonium metavanadate and sodium dihydrogen phosphate as raw materials, citric acid as a chelating agent, polyvinylpyrrolidone as a structure directing agent and an additional carbon source, wherein the mass ratio of the mass of the polyvinylpyrrolidone to the mass of the sodium dihydrogen phosphate is x:2.3684, and x =2, 3 or 4; the polyvinylpyrrolidone-induced vanadium sodium phosphate composite anode material is prepared by a one-step method, and is irregular Na 3 V 2 (PO 4 ) 3 And layered Na 3 V 3 (PO 4 ) 4 The two-phase composite material is formed, and a nitrogen-doped carbon coating layer formed after sintering polyvinylpyrrolidone is arranged outside the two-phase composite material.
2. The method for preparing the polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material of claim 1, characterized by comprising the following steps: the method comprises the following specific steps:
(1) taking sodium dihydrogen phosphate, ammonium metavanadate and citric acid with the molar ratio of 82.21:5.46:1, adding the sodium dihydrogen phosphate and the ammonium metavanadate into 100mL of deionized water, heating to 70 ℃ at constant temperature, continuously stirring, and reacting to form a yellow transparent solution of the sodium vanadium phosphate; slowly adding citric acid into the yellow transparent solution, and finally stabilizing the color in blue;
(2) slowly adding polyvinylpyrrolidone into the blue solution prepared in the step (1) until the polyvinylpyrrolidone is completely dissolved; wherein the mass ratio of polyvinylpyrrolidone to sodium dihydrogen phosphate is x:2.3684, and x =2, 3 or 4, and stirring at constant temperature until the precursor solution is concentrated into 20ml of viscous colloid;
(3) placing the viscous colloid prepared in the step (2) in a forced air oven, and drying for 12h at 80 ℃ by forced air drying to obtain a precursor;
(4) and (4) presintering the precursor obtained in the step (3) at 450 ℃ for 4h in the atmosphere of nitrogen, and then, performing final burning at 700 ℃ for 6h to obtain a final product.
3. The application of the polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material as claimed in claim 1 in a sodium ion battery.
4. Use according to claim 3, characterized in that: the specific method comprises the following steps:
(1) preparing a positive electrode material: the polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material is used as an active substance of a positive electrode material, and the ratio of the active substance to the negative electrode material is as follows (7: 2: 1, mixing the conductive filler acetylene black and the adhesive polyvinylidene fluoride in 1.4 mL of N-methylpyrrolidone NMP solvent; placing the mixture in a ball milling tank, performing unidirectional ball milling for four hours to obtain slurry, coating the slurry on a carbon-coated aluminum foil, performing forced air drying for four hours at the temperature of 45 ℃, and performing vacuum drying for 6 hours at the temperature of 120 ℃ to obtain a positive electrode material;
(2) assembling the battery: taking the anode material prepared in the step (1) as an anode, metal sodium as a cathode, a ceramic Celgard diaphragm as a diaphragm and an electrolyte as NaClO 4 + EC/DEC +5% FEC; wherein, NaClO 4 EC, DEC and FEC denote sodium perchlorate, ethylene carbonate, diethyl carbonate and fluoroethylene carbonate, respectively; 1M NaClO 4 Dissolving the mixture in an EC/DEC system with the volume ratio of 1:1, and simultaneously adding 5 wt% of FEC to prepare electrolyte; assembled into a 2016 type button cell.
CN202210733410.1A 2022-06-27 2022-06-27 Polyvinylpyrrolidone-induced vanadium sodium phosphate composite positive electrode material, and preparation method and application thereof Active CN115036486B (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160156019A1 (en) * 2014-12-02 2016-06-02 Dongguk University Industry-Academic Cooperation Foundation Method for preparing polyanion-carbon nanofiber composite cathode active material
CN105655565A (en) * 2016-04-08 2016-06-08 苏州大学 Composite cathode material of sodium-ion battery and preparation method of composite cathode material
WO2020174487A1 (en) * 2019-02-28 2020-09-03 International Advanced Research Centre For Powder Metallurgy And New Materials (Arci) Microwave assisted sol-gel process for preparing in-situ carbon coated electrode materials and the product thereof
US20210242451A1 (en) * 2020-02-04 2021-08-05 Korea Advanced Institute Of Science And Technology Metal-Doped Sodium Vanadium Fluorophosphate/Sodium Vanadium Phosphate (Na3V2(PO4)2F3/Na3V2(PO4)3) Composite for Sodium-Ion Storage Material
CN113659146A (en) * 2021-08-12 2021-11-16 中北大学 Potassium lanthanum silicon ternary codoped vanadium sodium phosphate electrode material and preparation method and application thereof

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160156019A1 (en) * 2014-12-02 2016-06-02 Dongguk University Industry-Academic Cooperation Foundation Method for preparing polyanion-carbon nanofiber composite cathode active material
CN105655565A (en) * 2016-04-08 2016-06-08 苏州大学 Composite cathode material of sodium-ion battery and preparation method of composite cathode material
WO2020174487A1 (en) * 2019-02-28 2020-09-03 International Advanced Research Centre For Powder Metallurgy And New Materials (Arci) Microwave assisted sol-gel process for preparing in-situ carbon coated electrode materials and the product thereof
US20210242451A1 (en) * 2020-02-04 2021-08-05 Korea Advanced Institute Of Science And Technology Metal-Doped Sodium Vanadium Fluorophosphate/Sodium Vanadium Phosphate (Na3V2(PO4)2F3/Na3V2(PO4)3) Composite for Sodium-Ion Storage Material
CN113659146A (en) * 2021-08-12 2021-11-16 中北大学 Potassium lanthanum silicon ternary codoped vanadium sodium phosphate electrode material and preparation method and application thereof

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