CN111834628A

CN111834628A - Na-doped NH4V4O10Nano sheet material and preparation method and application thereof

Info

Publication number: CN111834628A
Application number: CN202010736966.7A
Authority: CN
Inventors: 张睿智; 黄靖栋; 尹岚; 董勇
Original assignee: Hunan Institute of Technology
Current assignee: Hunan Institute of Technology
Priority date: 2020-07-28
Filing date: 2020-07-28
Publication date: 2020-10-27
Anticipated expiration: 2040-07-28
Also published as: CN111834628B

Abstract

Na-doped NH₄V₄O₁₀A nano sheet material and a preparation method and application thereof relate to the technical field of zinc ion battery electrode materials. The invention prepares Na by a one-step hydrothermal assembly mode_xNH₄V₄O₁₀Nanosheet material, NH inserted therein₄ ⁺Can be used as a 'pillar' between vanadium oxide layers to prevent destructive structural change in the ion insertion/extraction process; NH (NH)₄ ⁺And the N-H-O bond network between the vanadium oxide layer increases the structural stability and greatly improves the Na_xNH₄V₄O₁₀Cycling stability of electrode materials with nanosheet material as the active material. In general, the ultrathin nano-active material shows excellent electrochemical performance, and has good Zn due to the two-dimensional nano-sheet morphology and the adjustable and large interlayer spacing²⁺Storage capacity and ultrafast kinetics of ion intercalation/deintercalation, the above NH₄V₄O₁₀The nano sheet material has higher specific capacity, good rate capability and cycling stability capability, and wide application prospect.

Description

Na-doped NH4V4O10Nano sheet material and preparation method and application thereof

Technical Field

The invention relates to the technical field of electrode materials of zinc ion batteries, in particular to Na-doped NH₄V₄O₁₀A nano sheet material, a preparation method and application thereof.

Background

The secondary water system zinc ion battery theoretically has the advantages of safety, low price, environmental protection and high energy density, and the secondary water system Zinc Ion Battery (ZIBs) with high energy density is expected to meet the increasing requirements of safety and sustainable energy storage equipment in the future. However, one significant challenge that currently hinders practical application of aqueous zinc-ion batteries is the lack of suitable positive electrode materials. In recent years, MnO₂Due to its high theoretical capacity (300 mAh g)^-1) Low cost and low toxicity are of increasing concern. However, MnO₂In the continuous insertion of Zn²⁺Undergo a complex phase transition and exhibit limited specific capacity or poor cycling performance. Prussian Blue (PB) and similar materials are of great interest due to their high operating voltages, but most suffer from low capacity. In view of this, developing materials with longer cycle life remains a significant challenge.

Vanadium oxide (V) due to abundant resources₂O₅) The vanadium oxide and vanadate can be widely applied to lithium ion batteries and sodium ion batteries, and simultaneously, the vanadium oxide and vanadate have great potential in application of aqueous secondary zinc ion batteries. Na having a large ionic radius when synthesizing a zinc vanadate ion electrode material⁺And K⁺Can stabilize the structure and enlarge the interplanar spacing and realize reversible Zn²⁺Intercalation/deintercalation, although the synthetic sodium/potassium vanadate can sustain a long cycle life, due to Na⁺And K⁺The specific capacity of the electrode material is influenced to a certain extent.

Disclosure of Invention

According to the inventionOne purpose is to synthesize Na-doped NH with higher specific capacity aiming at the defect that the specific capacity of the existing vanadate material is lower₄V₄O₁₀A nanosheet material.

In order to achieve the above object, the present invention provides a Na-doped NH₄V₄O₁₀A method of preparing a nanoplatelet material, comprising the steps of:

a. adding a proper amount of NH₄VO₃Adding a proper amount of NaNO₃Fully stirring and uniformly mixing the solution;

b. b, dripping a proper amount of ammonia water into the solution prepared in the step a, uniformly stirring, and adjusting the pH value of the solution to be alkalescent;

c. placing the solution with the pH value adjusted to be alkalescent in the step b into a closed reaction kettle, carrying out hydrothermal reaction, heating to 120-200 ℃, keeping for 2-16 hours, and naturally cooling to room temperature to obtain a solid product;

d. filtering to separate out a solid product, washing the solid product clean, and drying to obtain a product Na_xNH₄V₄O₁₀·0.26H₂O, wherein the value of x is between 0.01 and 2; the product is the Na-doped NH₄V₄O₁₀A nanosheet material.

Preferably, NH in step a₄VO₃With NaNO₃NaNO in solution₃The mass ratio of (A) to (B) is 2: 1-3.5: 1.

wherein, in the step b, the Ph value of the solution is adjusted to 7.3-7.7.

Preferably, in step c, the hydrothermal reaction temperature is 180 ℃ and the holding time is 6 hours.

Further, NH in step a₄VO₃With NaNO₃NaNO in solution₃In a mass ratio of 59: 21.

Preferably, in step b, the Ph of the solution is adjusted to 7.5.

In addition, the invention also provides Na-doped NH₄V₄O₁₀Nanosheet material prepared by the method described above.

In addition, the invention also relates to the Na-doped NH₄V₄O₁₀The application of the nanosheet material as a positive electrode material of a zinc ion battery.

The invention prepares Na by a one-step hydrothermal assembly mode_xNH₄V₄O₁₀The ultrathin nanometer active material shows excellent electrochemical performance, and has good Zn due to the two-dimensional nanometer sheet shape and adjustable layer spacing²⁺Storage capacity and ultrafast kinetics of ion intercalation/deintercalation. Using the above Na_xNH₄V₄O₁₀The electrode material prepared by the nano sheet material has good rate capability and cycle stability, which is attributed to the dual-ion intercalation Na thereof_xNH₄V₄O₁₀Na in the nano sheet⁺Doping embedding expands the interplanar spacing, and the structure has larger interlayer spacing, Zn²⁺Ions are more easily embedded and separated in the charging and discharging process, the material has the characteristic of holes and larger specific surface area, the permeation of electrolyte is facilitated, the contact area of an electrode material and the electrolyte can be increased, and Zn can be borne more easily at the same time²⁺Volume expansion due to embedding during cycling. Because the material has the advantages between layers, better electrochemical performance can be obtained: 1) inserted NH₄ ⁺Can act as a "pillar" between the vanadium oxide layers to prevent destructive structural changes during ion insertion/extraction. 2) NH (NH)₄ ⁺And an N-H-O bond network between the vanadium oxide layer and the vanadium oxide layer increases structural stability and plays a key role in improving the cycle stability of the electrode material. 3) NH in contrast to other existing metal vanadates (e.g., zinc, potassium, sodium, silver, copper, etc.)₄ ⁺Has lower density and molecular weight, and thus higher specific capacity.

Description of the drawings:

FIG. 1 shows Na_xNH₄V₄O₁₀An SEM topography of the nanosheet material, wherein a is the topography at low magnification and b is the topography at high magnification;

in FIG. 2, a is Na_xNH₄V₄O₁₀TEM morphology of nanosheet material under low resolution, b is Na_xNH₄V₄O₁₀A TEM topography of the nanosheet material under high resolution, wherein an inset in b is an electron selective area diffractogram;

FIG. 3 is Na_xNH₄V₄O₁₀An X-ray diffraction pattern of the nanoplatelets;

in FIG. 4, a is Na_xNH₄V₄O₁₀An XPS spectrum full spectrum of the nanosheet material, wherein b is a Na element characteristic peak diagram, and c is a O, V element characteristic peak diagram;

FIG. 5 shows Na_xNH₄V₄O₁₀Thermogravimetric detection curve of the nanosheet material;

FIG. 6 shows Na_xNH₄V₄O₁₀CV plot of nanosheet material;

FIG. 7 shows Na_xNH₄V₄O₁₀A specific capacity voltage curve of the nanosheet material;

in FIG. 8, a is Na_xNH₄V₄O₁₀The nano sheet material is 500mA g^-1Cycle performance at current density, b is Na_xNH₄V₄O₁₀The nano-sheet material is in 2A g^-1A plot of cycling performance at current density;

FIG. 9 shows Na_xNH₄V₄O₁₀Multiplying power performance diagrams of the nanosheet material under different current magnitudes;

FIG. 10 shows Na_xNH₄V₄O₁₀An X-ray diffraction pattern of the nanosheet material in a fully discharged state;

in FIG. 11 a is Na_xNH₄V₄O₁₀XPS spectrum of Zn element of nanosheet material in complete discharge state, b is Na_xNH₄V₄O₁₀XPS spectra of O, V elements of the nanoplatelets in the fully discharged state.

Detailed Description

In order to facilitate the understanding of those skilled in the art, the present invention will be further described with reference to the following examples, which are not intended to limit the present invention. It should be noted that the following examples are carried out in the laboratory, and it should be understood by those skilled in the art that the amounts of the components given in the examples are merely representative of the proportioning relationship between the components, and are not specifically limited.

Firstly, preparing a target product.

In this example Na_xNH₄V₄O₁₀The preparation method of the nanosheet material comprises the following steps:

a. adding a proper amount of NH₄VO₃Adding a proper amount of NaNO₃Fully stirring and uniformly mixing the solution; specifically, NH₄VO₃With NaNO₃NaNO in solution₃The mass ratio of (A) to (B) is 2: 1-3.5: 1, for example, 0.21 g of NaNO can be used first₃Adding into 30 ml deionized water to prepare NaNO₃Solution, 0.59 g of ammonium metavanadate (NH)₄VO₃) Adding NaNO₃The solution is fully stirred and uniformly mixed, the uniformly mixed solution is a suspension with trace precipitation, the solution is weakly acidic, and the pH value is 6.6-6.7.

b. And (b) dropwise adding a proper amount of ammonia water into the solution prepared in the step a, uniformly stirring, and adjusting the pH value of the solution to be alkalescent. Specifically, the Ph of the solution may be adjusted to 7.3 to 7.7 in this step, preferably Ph 7.5. It is emphasized that the alkalescence of the solution can increase the solution degree of ammonium metavanadate, and the ammonia water can allow excessive ammonia ions to exist in the solution after being added, which is the subsequent synthesis of Na_xNH₄V₄O₁₀The conditions under which the nanoplatelets are very important.

c. And c, placing the solution with the pH value adjusted to be alkalescent in the step b into a closed reaction kettle, carrying out hydrothermal reaction, heating to 120-200 ℃, keeping for 2-16 hours, and naturally cooling to room temperature to obtain a solid product. During the specific operation, the temperature can be raised to about 180 ℃, the heat preservation time can be properly adjusted according to the hydrothermal reaction temperature, and the heat preservation time can be kept for 6 hours.

d. Filtering componentSeparating out a solid product, washing the solid product, and drying the solid product at the temperature of 60 ℃ for about 12 hours to obtain a product Na_xNH₄V₄O₁₀·0.26H₂O, wherein the value of x is between 0.01 and 2; the product is Na-doped NH₄V₄O₁₀A nanosheet material.

Secondly, measuring the phase, the morphology and the performance of the product.

1. And (3) analyzing the appearance of the SEM: in order to determine the morphology of the product, SEM scanning electron microscopy was performed on the product sample, and the results are shown in fig. 1. As can be seen from the figure, the product is formed by stacking a plurality of thin sheet layers with the thickness of nanometer level, the thin sheet layers are in a cotton shape, the material formed by stacking the two-dimensional structures of the thin sheet layers has extremely large specific surface area, and Zn can be reduced theoretically during cyclic charge and discharge²⁺Energy barrier of ion embedded active material lattice, shortening Zn²⁺The distance between the ions and the electrolyte is convenient for the immersion of the electrolyte, and the electrochemical performance in cyclic charge and discharge and multiplying power charge and discharge can be further improved.

2. TEM analysis: the TEM morphology of the product is shown in fig. 2 a. The TEM images show a more clear sheet structure, which is consistent with the SEM topography, again verifying that the synthesized product consists of nano-sheets stacked layer by layer. Comparing with a scale, the width of the nano sheet can be estimated to be about 150nm, the high-transmittance nano sheet proves that the nano sheet is well dispersed, the bent lamellar structure proves that the nano sheet has better flexibility, meanwhile, obvious lattice fringes can be seen in a nano sheet high resolution graph in b, and the distance between two adjacent lattices is 0.35 nm through measurement, wherein the distance corresponds to NH₄V₄O₁₀The {110} interplanar spacing of monoclinic crystals. By characterization of electron selective area diffraction (inset in b), Na was verified_xNH₄V₄O₁₀The single crystal structure of the nano-sheet.

3. X-ray diffraction (XRD) analysis: the analysis results shown in FIG. 3 were compared with PDF card (JCPDS 31-0075), which showed good agreement with NH in the above examples₄V₄O₁₀Similar crystal structure (mono)Orthorhombic), and few peaks were detected, indicating that the synthesized product was of high purity. The intensity of the {001} diffraction peak and the {110} crystal face diffraction peak in the period is highest, which indicates that the nano-sheet has a preferred orientation, wherein the {001} interlayer distance is 10.13A, and NH is compared₄V₄O₁₀The reason for the interlayer distance of the corresponding crystal plane being 9.60A should be because of Na⁺Doping inserts open the interplanar spacing in a manner that allows it to have a greater interlaminar spacing, so that Zn²⁺Ions are easier to be inserted and extracted in the charging and discharging process. According to the XRD pattern, the synthesis of Na-doped NH can be judged₄V₄O₁₀Nanosheet material (i.e., Na)_xNH₄V₄O₁₀Nanosheet material), and the peak intensity is weak, and the transverse peak position width of a single peak is large, so that the prepared Na can be obtained_xNH₄V₄O₁₀The nanosheet material has a smaller grain size and possesses a lower crystallinity, has a nanostructure, and the results are consistent with SEM and TEM images. Since the size of the ion diffusion channel and the lattice are critical to the electrochemical performance, the product has larger diffusion channel ANVO ({ 001} interlayer distance is 10.13A), theoretically having more excellent performance in terms of specific capacity, rate performance and long-term cycling stability.

4. Elemental analysis: elemental analysis of the product using X-ray photoelectron spectroscopy resulted in the graph shown in fig. 4, giving a spectrum between 0eV and 1300eV from the full scan spectrum (i.e. a) indicating: four peaks at 400eV, 517.5eV, 530eV and 1070eV are observed from small to large in the product, and correspond to N, V, O and Na, respectively, so that the Na element is embedded into NH in a doped form₄V₄O₁₀In the crystal structure. In fig. 4 b shows the characteristic peak of the Na element 1s orbital, located at 1070 eV. FIG. 4c shows three characteristic peaks, corresponding to 2p of element V at 517.5eV_3/2The region, consisting of two characteristic peaks, 517.4 eV and 515.9 eV, whose content ratio, calculated as 1.75: 1, respectively assigned to V (5)⁺) And V (4)⁺) 2p at 524eV corresponding to the element V_1/2(ii) a zone characteristic peak. Binding energy of O element 1sRespectively at 530.1 eV, 531.8 eV and 533.4 eV, respectively as O^2-Ions, OH^-Ions and adsorbed water or carbon oxygen groups.

5. Thermogravimetric differential thermal analysis: FIG. 5 shows the thermogravimetric differential thermal analysis curve of the product, in which the detection atmosphere is air and the temperature rise rate is 2 deg./min. In the figure, there is a weight loss of about 8.05% before 200 ℃, which is attributed to the loss of residual physically and chemically crystallized water in the material with increasing temperature. The second weight loss started at about 200 ℃ and stopped at 400 ℃ and this mass loss was the largest part of the overall test, due to Na_xNH₄V₄O₁₀The material is decomposed, and the ammonium ions in the material are discharged in the form of ammonia gas to cause mass loss. At the same time, there is also an endothermic peak of significant intensity starting at 200 ℃ and starting at 400 ℃ which is caused during the deammonification of the composite, the weight loss being about 22.8% in this temperature interval. As the temperature continues to rise, there is a significant mass increase after 500 ℃ to around 600 ℃, corresponding to a significant exothermic peak of significant intensity, due to the mass increase caused by further oxidation of the vanadium element to higher oxides by the oxygen in the air, which is approximately 2.45% of the mass increase.

6. And (3) electrochemical performance testing: after the product prepared in example, ketjen black and PVDF were mixed and ground in a mass ratio of 7:2:1, N-methyl-2-pyrrolidone (NMP) was diluted in a ratio to PVDF (1: 43) and stirred for 24 hours. Coating the stirred slurry on a Ti foil, pre-drying, putting into a vacuum drying oven, drying at 90 ℃ for 12 hours, taking out a dried pole piece, punching into a wafer with the diameter of 12mm, and performing Zn-Na in a common environment (without a glove box)_xNH₄V₄O₁₀And (3) assembling the half cell, wherein the counter electrode is a polished zinc sheet, the diaphragm is a Whatman glass fiber membrane, and the electrolyte is zinc sulfate aqueous solution. The assembled cell was subjected to a standing treatment for 12 hours, followed by various tests for electrochemical properties. Using an electrochemical workstation (CHI 604E, China) and a blue testing apparatus (Land CT)2001A, wuhan, china) to perform performance tests such as cycle performance analysis, rate performance analysis, voltammetry analysis, and the test voltage range is set to 0.4V-1.4V.

FIG. 6 shows the CV curve of the electrode with product as active material at a sweep rate of 0.1mV s over a test voltage range of 0.4 to 1.6V^-1. As shown, during the scan, for Zn/Zn²⁺3 pairs of different peaks are shown, with 3 peaks appearing in the cathodically scanned peak, indicating multistep zinc ion intercalation at 0.98V, 0.8V and 0.62V, respectively. In the anode scanning curve, three peaks respectively observed around 0.6V, 0.78V and 1.0V respectively correspond to Zn²⁺3 times of prolapse. As can be seen by combining the SEM image (FIG. 1) and TEM (FIG. 2), due to Na_xNH₄V₄O₁₀The nano-sheet layer active substance is formed by stacking a plurality of nano-scale sheet layers in a cotton shape, and the two-dimensional structure of the sheet layers and the stacking mode thereof ensure that the sheet layers have extremely large specific surface area, thereby reducing Zn during cyclic charge and discharge²⁺The energy barrier of ions embedded into the crystal lattice of the active material shortens Zn²⁺The distance between the ions to be embedded and removed facilitates the immersion of the electrolyte, and the dynamic process of the ion removal on the electrode is better because a large number of gaps exist between the nano-sheet layers of the product. The position of the first cycle CV peak and the last three cycles are shifted, which indicates that there are some side reactions during the first charge and discharge, in Zn²⁺Some irreversible phase transformation occurs when ions are inserted into the lattice, which leads to an inserted Zn²⁺The ionic portion cannot be extracted. In

subsequent cycles

2, 3 and 4, CV maps can find that the overlapping of each peak is relatively good, which proves that Zn in subsequent cycles²⁺The reversibility and stability of the intercalation and deintercalation of ions are good.

FIG. 7 is a second cycle charge-discharge curve of an electrode using the product as an active material, when the electrode is cycled between a voltage range of 0.4V and 1.4V. Wherein the current density is 500mAh g^-1The charging specific capacity is 398mAh g respectively^-1The specific discharge capacity is 394mAh g^-1The coulombic efficiency can reach 98.9 percent, which shows that the product keeps good coulombic efficiency. When the three pairs of redox peaks corresponding to the CV curves in FIG. 6 are compared, it can be seen thatThe charge and discharge curve has better goodness of fit.

FIG. 8 shows the reaction with Na_xNH₄V₄O₁₀The electrode with the nanosheet material as the active material was at 500mA g^-1And 2A g^-1Cycling performance at 60 and 300 cycles at current density. It can be seen in both sets of cycling data that the specific capacity of the second cycle is higher than the specific capacity of the first cycle, since the increase in voltage across the first cycle results in more ions entering the Na_xNH₄V₄O₁₀The capacity increase is also caused by the complete wetting of more electrode material inside the lattice, in addition to the intercalation and de-intercalation process of zinc ions. In FIG. 8 (a), the current density was 500mA g^-1The first circle of the electrode has a specific discharge capacity of 334mAh g^-1The specific capacity is improved to 397mAh g after the second and third cycles of circulation^-1The retention rate is 65% compared with the highest capacity after 60 cycles.

At 2A g^-1Under the current density, the first discharge specific capacity of the electrode is 271 mAh g^-1317mAh g was obtained at the third cycle^-1The capacity retention rate after 300 cycles is 56%. The electrode shows better cycle performance, particularly after the first dozens of circles of attenuation are stable, the capacity change curve tends to be stable to a certain extent, and the surface stress is released better due to the fluffy flocculent appearance and the dispersed nano-sheet layer structure so as to absorb more Zn²⁺The volume expansion caused by the ions embedded into the crystal lattice inhibits the pulverization and peeling processes of the nano-sheet material. Meanwhile, along with the complete infiltration of the electrolyte after dozens of circles, the part which is not contacted with the electrolyte is activated to a certain degree, and Na_xNH₄V₄O₁₀A large number of gaps exist among the nano sheets, and the de-intercalation kinetic process on the electrode is good.

FIG. 9 shows the current density at increasing levels with Na_xNH₄V₄O₁₀Rate capability of the nanosheet as an electrode for the active material. As shown, it exhibited a higher capacity at each current and was at 0.5A g^-1Providing about 350mAh g^-1The specific capacity of (A). When the current is from 0.5A g^-1Gradually increased to 15A g^-1The discharge capacity was about 350mAh g^-1，250mAh g^-1、175mAh g^-1、150mAh g^-1、80mAh g^-1And 50mAh g^-1. At return to 0.5A g^-1Then, 258mAh g is recovered^-1The discharge capacity of (2). After 10 cycles, the discharge capacity dropped to 172mAh g^-1The result shows that the electrode has better rate performance in the process of high-current charge and discharge. The better rate performance is attributed to the unique appearance and Na of the product⁺Ions being intercalated into NH in doped form₄V₄O₁₀The multi-layer ultrathin nano-sheets effectively shorten Zn²⁺Diffusion path in the ion embedding and separating process, so that Zn is ensured during large charge and discharge current²⁺The ions can be quickly inserted and extracted. And Na⁺Ions being intercalated into NH in doped form₄V₄O₁₀The crystal lattice of (1) supports the interplanar spacing and allows Zn to be in²⁺The ions have wider insertion and extraction channels at high currents.

To analyze the evolution of the crystalline structure of the product during electrochemical testing, the product was examined by ex situ XRD in the fully discharged state. FIG. 10 shows the reaction with Na_xNH₄V₄O₁₀The XRD pattern of the electrode in the fully discharged state as an active material was made of the nanosheet material. As can be seen from FIG. 10, in the completely discharged state, the second phase Zn is observed₃V₂O₇(OH)₂·2H₂Formation of O (JCPDS number 87-0417) and formation of the phase vs Na_xNH₄V₄O₁₀The zinc storage of the nano-sheets contributes to a certain extent. In addition, the {001} interplanar spacing of the electrodes after discharge was significantly larger than the lattice distance of the prepared ANVO powder, indicating the insertion of Zn²⁺And H₂The O molecule obviously increases the interplanar spacing of ANVO, H₂The O molecules coordinate in the interlayer space during discharge/charge, which can be further demonstrated by XPS curve analysis in fig. 11. H₂The O molecule acts as a "pillar" between the intermediate layers of ANVO during the process, providing a volume forIn addition to the amount of NH fixed₄ ⁺Cooperatively supporting the overall structure.

Finally, for Na in the fully discharged state (discharged to 0.4V)_xNH₄V₄O₁₀The active material was also subjected to ex-situ XPS spectroscopy to gain insight into its redox behavior during discharge, and the results are shown in figure 11. As can be seen from the figure, Zn 2p signals at 1022.3 (2 p 3/2) and 1045.4 (2 p 1/2) eV appear in the ex-situ XPS spectrum at full discharge, indicating Zn²⁺Ions were inserted into ANVO, and Na was found after insertion of zinc ions_xNH₄V₄O₁₀The valence of the medium vanadium element is reduced. The broadened peak at 532.5 eV in the O1 s region indicates more H₂O molecule is embedded into Na_xNH₄V₄O₁₀In the crystal lattice, this is advantageous in that the crystal structure of the active material is well maintained during discharge.

In summary, the above examples prepare Na by a one-step hydrothermal assembly method_xNH₄V₄O₁₀The ultrathin nanometer active material shows excellent electrochemical performance, and has good Zn due to the two-dimensional nanometer sheet shape and adjustable layer spacing²⁺Storage capacity and ultrafast kinetics of ion intercalation/deintercalation. Using the above Na_xNH₄V₄O₁₀The electrode material prepared by the nano sheet material has good rate capability and cycle stability, which is attributed to the dual-ion intercalation Na thereof_xNH₄V₄O₁₀Na in the nano sheet⁺Doping embedding expands the interplanar spacing, and the structure has larger interlayer spacing, Zn²⁺Ions are more easily embedded and separated in the charging and discharging process, and the material has the characteristic of holes and larger specific surface area, is favorable for the permeation of electrolyte, can increase the contact area of an electrode material and the electrolyte and can bear Zn more simultaneously²⁺Volume expansion due to embedding during cycling. The material has advantages between layers, so thatTo obtain better electrochemical performance: 1) inserted NH₄ ⁺Can act as a "pillar" between the vanadium oxide layers to prevent destructive structural changes during ion insertion/extraction. 2) NH (NH)₄ ⁺And an N-H-O bond network between the vanadium oxide layer and the vanadium oxide layer increases structural stability and plays a key role in improving the cycle stability of the electrode material. 3) NH in contrast to other existing metal vanadates (e.g., zinc, potassium, sodium, silver, copper, etc.)₄ ⁺Has lower density and molecular weight, and thus higher specific capacity.

The above embodiments are preferred implementations of the present invention, and the present invention can be implemented in other ways without departing from the spirit of the present invention.

Finally, it should be emphasized that some of the descriptions of the present invention have been simplified to facilitate the understanding of the improvements of the present invention over the prior art by those of ordinary skill in the art, and that other elements have been omitted from this document for the sake of clarity, and those skilled in the art will recognize that these omitted elements may also constitute the content of the present invention.

Claims

1. Na-doped NH₄V₄O₁₀The preparation method of the nano sheet material is characterized by comprising the following steps:

2. The Na-doped NH of claim 2₄V₄O₁₀The preparation method of the nano sheet material is characterized by comprising the following steps: NH in step a₄VO₃With NaNO₃NaNO in solution₃The mass ratio of (A) to (B) is 2: 1-3.5: 1.

3. the Na-doped NH of claim 1₄V₄O₁₀The preparation method of the nano sheet material is characterized by comprising the following steps: in step b, the pH value of the solution is adjusted to 7.3-7.7.

4. The Na-doped NH of claim 1₄V₄O₁₀The preparation method of the nano sheet material is characterized by comprising the following steps: in the step c, the hydrothermal reaction temperature is 180 ℃, and the heat preservation time is 6 hours.

5. The Na-doped NH of claim 2₄V₄O₁₀The preparation method of the nano sheet material is characterized by comprising the following steps: in step a NH₄VO₃With NaNO₃NaNO in solution₃In a mass ratio of 59: 21.

6. The Na doped NH of claim 3₄V₄O₁₀The preparation method of the nano sheet material is characterized by comprising the following steps: in step b, the Ph of the solution was adjusted to 7.5.

7. Na-doped NH₄V₄O₁₀A nanoplatelet material characterized in that: prepared by the method of any one of claims 1 to 6.

8. The Na doped NH of claim 7₄V₄O₁₀Nanosheet material as zincApplication of positive electrode material of ion battery.