Preparation method and application of two-dimensional vanadium oxide

Abstract

The invention relates to a preparation method and application of a two-dimensional metal oxide, belongs to the field of inorganic metal nanomaterials, and particularly discloses a novel preparation method of the two-dimensional metal oxide. The method comprises the following steps: (1) taking a parent material as a negative electrode, immersing the negative electrode and a counter electrode into an electrolyte, and carrying out electrochemical reaction to obtain an intercalated two-dimensional vanadium oxide; and (2) stripping the intercalated two-dimensional vanadium oxide obtained in the step (1) to obtain the two-dimensional vanadium oxide, wherein the parent material is a Van der Waals layered vanadium compound. The preparation method of the two-dimensional metal oxide is widened, and development of the application field of the two-dimensional metal oxide is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic metal nanomaterials, and in particular to a preparation method and application of a two-dimensional vanadium oxide. Background Art

[0002] Over the past few decades, vanadium oxides have attracted considerable attention and experienced rapid development due to their potential applications in various fields, including the preparation and application of ultrathin or two-dimensional vanadium oxides. Due to the unique properties endowed by quantum confinement and extremely high specific surface area, two-dimensional vanadium oxides may have great application potential in low-energy electronics, flexible electronics, catalysis, batteries, and other fields.

[0003] Few methods have been disclosed for preparing two-dimensional metallic vanadium oxides. Currently known is a method for preparing two-dimensional α-V2O5 using formamide intercalation, which has been applied to lithium-ion battery cathode materials. Compared to bulk α-V2O5, this two-dimensional α-V2O5 exhibits greater reversible capacity, better stability, and ultrahigh-rate capability. This suggests that two-dimensional vanadium oxides possess significant performance advantages over their bulk counterparts. However, limited preparation methods have hindered the development of their applications. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a two-dimensional vanadium oxide and its preparation method and use, and provides a new preparation method of two-dimensional vanadium oxide.

[0005] To achieve the above-mentioned object, the first aspect of the present invention provides a method for preparing a two-dimensional vanadium oxide, the method comprising the following steps: (1) using a parent material as a negative electrode, immersing the negative electrode and a counter electrode in an electrolyte, and performing an electrochemical reaction to obtain an intercalated two-dimensional vanadium oxide;

[0006] (2) peeling off the intercalated two-dimensional vanadium oxide obtained in step (1) to obtain the two-dimensional vanadium oxide;

[0007] Wherein, the matrix material is a van der Waals layered vanadium compound.

[0008] Furthermore, the matrix material is VOCl.

[0009] Furthermore, the quaternary ammonium salt is selected from one or more of tetramethylammonium bromide, tetrabutylammonium bromide, tetraethylammonium bromide, and tetrahexylammonium bromide.

[0010] Furthermore, the voltage of the electrochemical reaction is 2-15V, and the time is 10min-1h.

[0011] Furthermore, in step (2), the stripping is performed by adding the intercalated two-dimensional vanadium oxide obtained in step (1) into a solvent for dispersion.

[0012] Furthermore, the dispersion solvent is a polar solvent, preferably at least one selected from deionized water, N-methylpyrrolidone, and methanol.

[0013] The second aspect of the present invention provides a two-dimensional metal oxide, which is prepared by the method described in the first aspect of the present invention.

[0014] The third aspect of the present invention provides an application of a two-dimensional metal oxide in an ion battery electrode material, wherein the two-dimensional vanadium oxide is prepared by the method described in the first aspect of the present invention.

[0015] A fourth aspect of the present invention provides a positive electrode material for a lithium-ion battery, wherein the positive electrode material for a lithium-ion battery comprises a two-dimensional vanadium oxide, wherein the two-dimensional vanadium oxide is prepared by the method described in the first aspect of the present invention.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0017] 1. The present invention discloses a new method for preparing two-dimensional vanadium oxides. Through electrochemical reactions, on the one hand, a chemical reaction is caused in van der Waals layered vanadium compounds to remove elements other than vanadium and oxygen in the parent material without affecting the main structure inside the layer, so that the main structure in the parent material is retained; on the other hand, a quaternary ammonium salt is used to intercalate the van der Waals layered vanadium compound to facilitate the subsequent exfoliation of the two-dimensional material; the present invention broadens the preparation method of two-dimensional metal oxides and is conducive to the development of the application field of two-dimensional metal oxides.

[0018] 2. In the electrochemical reaction of the present invention, the thickness of the obtained two-dimensional vanadium oxide can be adjusted to 1-10 nm by controlling the length of the organic carbon chain of the quaternary ammonium salt cation in the electrolyte.

[0019] 3. In the electrochemical reaction, the present invention can improve the yield of two-dimensional vanadium oxide by regulating the electrolysis voltage and electrolysis time. For example, when the quaternary ammonium salt in the electrolyte is tetrabutylammonium bromide, the yield of the two-dimensional vanadium oxide is 70% after electrolysis at a voltage of 10 V for 20 minutes; the yield of the two-dimensional vanadium oxide is 40% after electrolysis at a voltage of 10 V for 10 minutes; and the yield of the two-dimensional vanadium oxide is 20% after electrolysis at a voltage of 5 V for 20 minutes.

[0020] 4. The electrode positive electrode material containing two-dimensional vanadium oxide of the present invention has good stability. -1 At a current density of 100 cycles, it still maintains a high specific capacity (105 mAh g-1 ).

[0021] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0023] Figure 1 This is the X-ray powder diffraction spectrum of the VOCl matrix material prepared in Preparation Example 1;

[0024] Figure 2 This is an atomic force microscope (AFM) photograph of the two-dimensional vanadium oxide A1 prepared in Example 1;

[0025] Figure 3 This is a transmission electron microscope (TEM) photograph of the two-dimensional vanadium oxide A1 prepared in Example 1;

[0026] Figure 4 Elemental energy spectrum of the two-dimensional vanadium oxide A1 prepared in Example 1;

[0027] Figure 5 is an X-ray photoelectron spectroscopy (XPS) graph of the two-dimensional vanadium oxide A1 prepared in Example 1;

[0028] Figure 6 The cyclic voltammetry curve of a lithium-ion battery assembled using a positive electrode sheet prepared using the two-dimensional vanadium oxide A1 prepared in Example 1;

[0029] Figure 7 The XPS graphs of the two-dimensional vanadium oxide A1 prepared in Example 1 during discharge in the voltage range of 2-3.7 V are as follows:

[0030] Figure 8 The specific capacity curves of battery I and battery II during 100 cycles of charge and discharge. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0032] A specific embodiment of the present invention discloses a method for preparing a two-dimensional metal oxide, the method specifically comprising the following steps: (1) using a parent material as a negative electrode, immersing the negative electrode and a counter electrode in an electrolyte, and performing an electrochemical reaction to obtain an intercalated two-dimensional metal oxide; (2) exfoliating the intercalated two-dimensional vanadium oxide obtained in step (1) to obtain the two-dimensional vanadium oxide;

[0033] Wherein, the matrix material is a van der Waals layered vanadium compound.

[0034] This invention uses van der Waals layered vanadium compounds as the matrix material and prepares two-dimensional vanadium oxides through an electrochemical reaction. On the one hand, the van der Waals layered vanadium compounds undergo a chemical reaction, removing elements other than vanadium and oxygen from the matrix material without affecting the main structure within the layers, thus preserving the matrix material's main structure. On the other hand, the van der Waals layered vanadium compounds are intercalated with quaternary ammonium salts, facilitating the subsequent exfoliation of the two-dimensional material. This invention broadens the preparation methods for two-dimensional vanadium oxides and is conducive to the development of two-dimensional metal oxide applications.

[0035] Furthermore, the intercalated two-dimensional vanadium oxide obtained in step (1) is a VO structure formed after atoms other than vanadium and oxygen in the parent structure are detached. The structure carries a negative charge and maintains overall charge neutrality with the quaternary ammonium salt positive ions in the interlayer.

[0036] Furthermore, the parent material used in the method is vanadium oxychloride VOCl.

[0037] It should be noted that during the electrochemical reaction, the chlorine element in the VOCl bulk material falls off. Since the chlorine atoms are connected by bridging bonds in the bulk structure, the shedding of the chlorine atoms will not affect the main structure inside the sheet, so that the main structure in the parent material is retained. After the electrochemical reaction, due to the low stability of the low-valent vanadium ions, they are oxidized to obtain high-valent vanadium ions.

[0038] The VOCL matrix material of the present invention can be commercially available or prepared by any preparation method.

[0039] According to a specific embodiment of the present invention, the preparation method of the VOCl matrix material specifically comprises the following steps:

[0040] (a) V2O3 and VCl3 were mixed uniformly in a molar ratio of 1:1.5-1:2, placed in a glass tube, and vacuum-sealed;

[0041] (b) Heating the glass tube to 800-900 K at a heating rate of 1-10 K / min, maintaining the temperature for 120-150 h, and then cooling naturally;

[0042] (c) using ethanol to remove the residual VCl3 in the product to obtain the VOCl precursor material.

[0043] Specifically, in step (1), the present invention requires that the matrix material be fixed to the electrode clamp of the electrolytic cell. The material used to fix the matrix material is not particularly limited, as long as it can fix the matrix material and does not participate in the electrochemical reaction of the present invention. According to a preferred embodiment of the present invention, a stainless steel mesh is used to wrap the matrix material and clamp it to the electrode clamp of the electrolytic cell to serve as the negative electrode of the electrolytic cell.

[0044] The present invention has no special requirements on the counter electrode material. According to a preferred embodiment of the present invention, the counter electrode is a graphite electrode.

[0045] Furthermore, the electrolyte contains one or more quaternary ammonium salts, and the molecular formula of the quaternary ammonium salt is shown in formula (1):

[0046] wherein R1, R2, R3 and R4 are each independently selected from C1-C10 alkyl, X - F - 、Cl - Br - , I - 、HSO 4- or RCOO - .

[0047] The length of the longest organic carbon chain in the quaternary ammonium salt cation affects the intercalation and exfoliation effects of the electrochemical reaction. A too short organic carbon chain is not conducive to exfoliation. A longer organic carbon chain enhances the intercalation and exfoliation effects of the parent material. However, an excessively long carbon chain results in overly fragmented flakes, failing to produce the desired two-dimensional vanadium oxide. Preferably, the organic carbon chain in the quaternary ammonium salt cation contains 2-6 carbon atoms.

[0048] Furthermore, the quaternary ammonium salt is selected from one or more of tetramethylammonium bromide, tetrabutylammonium bromide, tetraethylammonium bromide, and tetrahexylammonium bromide, and further is tetrabutylammonium bromide.

[0049] Furthermore, the solvent used in the electrolyte can dissolve quaternary ammonium salts, has a large voltage window, and prevents the solvent from participating in electrochemical reactions. It can be acetonitrile, propylene carbonate, or ethylene carbonate. According to a specific embodiment of the present invention, the solvent in the electrolyte is acetonitrile.

[0050] Furthermore, the concentration of the quaternary ammonium salt in the electrolyte is 0.01-0.1 mol / L.

[0051] It should be noted that if the concentration of the quaternary ammonium salt in the electrolyte is too high, the post-processing of the electrochemical reaction will be more complicated, and if the concentration is too low, the parent material will not be sufficiently intercalated.

[0052] Furthermore, the concentration of the quaternary ammonium salt in the electrolyte is 0.05-0.07 mol / L.

[0053] Furthermore, the voltage of the electrochemical reaction is 2-15V, and the time is 10min-1h.

[0054] It should be noted that the voltage and time of the electrolysis in the present invention will affect the extent of the electrochemical reaction and the yield of the two-dimensional vanadium oxide. If the electrolysis voltage is too low, the parent material will be difficult to react; if the voltage is too high, the electrochemical reaction will be too intense, resulting in the peeled layers being too fine.

[0055] Furthermore, the voltage of the electrochemical reaction is 5-10V, and the time is 10-20min.

[0056] Furthermore, the stripping in step (2) is to add the intercalated two-dimensional vanadium oxide obtained in step (1) into a solvent for dispersion.

[0057] Furthermore, the solvent used for dispersion is a polar solvent. The polarity of the solvent will affect the dispersion effect. The saturation concentration of the dispersion decreases with the decrease of the polarity of the solvent, thereby affecting the thickness of the obtained two-dimensional vanadium oxide.

[0058] Furthermore, the polar solvent is at least one of deionized water, N-methylpyrrolidone, and methanol.

[0059] Furthermore, the dispersion is ultrasonic dispersion, the power of ultrasonic dispersion is 50-100W, and the time is 20-30min.

[0060] Furthermore, before stripping the matrix material after the electrochemical reaction, the matrix material after the reaction is cleaned to remove the inorganic salt remaining on the matrix material; the inorganic salt is mainly unreacted quaternary ammonium salt and a small amount of inorganic salt composed of removed Cl.

[0061] The present invention has no special requirements for the solvent used for cleaning, as long as it can clean away the residual inorganic salts, does not react with the obtained two-dimensional metal oxide, and does not introduce new impurities. According to a specific embodiment of the present invention, the present invention uses deionized water to clean the reacted matrix material.

[0062] Furthermore, the method of the first aspect of the present invention also includes a step of purifying the dispersed solution to remove unreacted parent material. The specific steps are: using a high-speed centrifuge to centrifuge the suspension obtained after ultrasound, and centrifuging at a speed of 1000-3000 rpm for 10-20 minutes to obtain a supernatant, which is a two-dimensional vanadium oxide dispersion; and drying the supernatant at a temperature of 50-100°C for 24-48 hours.

[0063] The second aspect of the present invention discloses a two-dimensional vanadium oxide, which is prepared by the method described in the first aspect of the present invention.

[0064] The structure and composition of the two-dimensional vanadium oxide of the present invention can be determined by characterization means such as transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), photoelectron spectroscopy, and high-resolution transmission electron microscopy photographs.

[0065] According to the method of the present invention, by using electrolyte quaternary ammonium salts with cationic organic carbon chains of different lengths in an electrochemical reaction, two-dimensional vanadium oxides with different thicknesses can be obtained, ranging from 1 to 10 nm.

[0066] Furthermore, it can be seen from the high-resolution transmission electron microscopy photos of the two-dimensional metal oxide that the two-dimensional metal oxide prepared in the present invention has a quasi-tetragonal short-range ordered microstructure.

[0067] In a third aspect, the present invention discloses the use of two-dimensional vanadium oxide in ion battery electrode materials, wherein the two-dimensional vanadium oxide is prepared by the method described in the first aspect of the present invention.

[0068] In a fourth aspect, the present invention provides a positive electrode material for a lithium-ion battery, wherein the positive electrode material for a lithium-ion battery comprises a two-dimensional vanadium oxide, wherein the two-dimensional vanadium oxide is prepared by the method of the first aspect of the present invention.

[0069] According to a specific embodiment of the present invention, the prepared two-dimensional vanadium oxide is applied to the preparation of lithium-ion battery positive electrode materials, and the prepared positive electrode plates are used to assemble batteries; the battery is subjected to cyclic voltammetry tests in the voltage range of 2V and 3.7V, and the obtained cyclic voltammetry curve can show the redox process of the two-dimensional vanadium oxide material.

[0070] The battery performance of the battery of the present invention is related to the thickness of the two-dimensional vanadium oxide used. The smaller the thickness of the two-dimensional vanadium oxide, the larger the specific surface area of ​​the material, which can provide more surface reaction sites for lithium ions, thereby improving the battery specific capacity. This conclusion can be drawn by comparing the specific capacity of Battery II and Battery I during 100 cycles of charge and discharge. In addition, the present application still has a high battery specific capacity after 100 cycles, indicating that the two-dimensional vanadium oxide prepared by the present invention has good stability.

[0071] The technical solution of the present invention is explained below with reference to specific embodiments.

[0072] Preparation Example 1

[0073] A method for preparing a VOCl matrix material comprises the following steps:

[0074] (a) V2O3 and VCl3 were mixed in a molar ratio of 1:1.8, placed in a glass tube, and vacuum-sealed;

[0075] (b) The glass tube was heated to 893 K at a rate of 1 K / min, maintained for 120 h, and then cooled naturally;

[0076] (c) removing residual VCl3 in the product using ethanol to obtain VOCl precursor material;

[0077] The X-ray powder diffraction test of VOCl matrix material is carried out, and the test results are as follows: Figure 1 As shown by Figure 1 It can be seen that the spectrum only contains the diffraction peak of VOCl, and no other peaks exist.

[0078] Example 1

[0079] A method for preparing a two-dimensional vanadium oxide A1 comprises the following steps:

[0080] (1) 10 mg of VOCl was wrapped with a stainless steel mesh and clamped on the electrode clamp of the electrolytic cell as the negative electrode. The counter electrode was a graphite electrode. The negative electrode and the counter electrode were immersed in an electrolyte solution of tetrabutylammonium bromide in acetonitrile with a concentration of 0.05 mol / L. The electrolyte was electrolyzed at a voltage of 10 V for 20 min to obtain an intercalated two-dimensional vanadium oxide.

[0081] (2) After the electrolysis is completed, the intercalated two-dimensional vanadium oxide obtained in step (1) is washed with deionized water, then immersed in deionized water, and ultrasonically dispersed at 100 W for 30 minutes to obtain a suspension containing the two-dimensional vanadium oxide A1;

[0082] (3) The suspension obtained in step (2) was centrifuged using a high-speed centrifuge at 3000 rpm for 10 min and dried at 80° C. for 24 h to obtain 7 mg of two-dimensional vanadium oxide A1 with a yield of 70%.

[0083] A1 was observed using an atomic force microscope (AFM), and the AFM photos obtained are as follows: Figure 3 As shown, from Figure 2 It can be seen that the thickness of A1 is relatively uniform, ranging from 1.2 to 2.8 nm.

[0084] A1 was observed using a transmission electron microscope (TEM), and the TEM images obtained are as follows: Figure 3 As shown, from Figure 3 It can be seen that A1 has good lamellar integrity and no obvious damage.

[0085] A1 was tested using an energy dispersive spectrometer (EDS), and the energy spectrum of each element in A1 was obtained as follows: Figure 4 As shown, from Figure 4 It can be seen that the elements in A1 are vanadium and oxygen, and it does not contain chlorine. A1 is vanadium oxide.

[0086] A1 was tested using photoelectron spectroscopy, and the spectrum obtained was as follows: Figure 5 As shown, from Figure 5 It can be seen that the vanadium ion in A1 is V +5 , so A1 is vanadium pentoxide.

[0087] Example 2

[0088] A method for preparing a two-dimensional vanadium oxide A2 comprises the following steps:

[0089] (1) 10 mg of VOCl was wrapped with a stainless steel mesh and clamped on the electrode clamp of the electrolytic cell. The counter electrode was a graphite electrode. The negative electrode and the counter electrode were immersed in an electrolyte solution of tetrabutylammonium bromide in acetonitrile with a concentration of 0.05 mol / L. The electrolyte was electrolyzed at a voltage of 10 V for 10 min to obtain an intercalated two-dimensional metal oxide.

[0090] (2) After the electrolysis is completed, the intercalated two-dimensional metal oxide obtained in step (1) is washed with deionized water, then immersed in deionized water, and ultrasonically dispersed at 100 W for 30 minutes to obtain a suspension containing the two-dimensional vanadium oxide A2;

[0091] (3) The suspension obtained in step (2) was centrifuged using a high-speed centrifuge at 3000 rpm for 10 min and dried at 80° C. for 24 h to obtain 4 mg of two-dimensional vanadium oxide A2 with a yield of 40%.

[0092] A2 was observed using AFM. From the AFM photos obtained, it can be seen that the thickness of A2 is relatively uniform, ranging from 1.2 to 2.8 nm.

[0093] A2 was observed using TEM. From the obtained TEM photos, it can be seen that A2 has good lamella integrity and no obvious damage.

[0094] A2 was tested using EDS. From the energy spectrum of each element in A2, it can be seen that the elements in A2 are vanadium and oxygen, and there is no chlorine element. A2 is vanadium oxide.

[0095] A2 was tested using photoelectron spectroscopy. From the obtained spectrum, it can be seen that the vanadium ions in A2 are V +5 , so A2 is vanadium pentoxide.

[0096] Example 3

[0097] A method for preparing a two-dimensional vanadium oxide A3 comprises the following steps:

[0098] (1) 10 mg of VOCl was wrapped with a stainless steel mesh and clamped on the electrode clamp of the electrolytic cell. The counter electrode was a graphite electrode. The negative electrode and the counter electrode were immersed in an electrolyte solution of tetrabutylammonium bromide in acetonitrile with a concentration of 0.05 mol / L. The electrolyte was electrolyzed at a voltage of 5 V for 20 min to obtain an intercalated two-dimensional metal oxide.

[0099] (2) After the electrolysis is completed, the intercalated two-dimensional metal oxide obtained in step (1) is washed with deionized water, then immersed in deionized water, and ultrasonically dispersed at 100 W for 30 minutes to obtain a suspension containing the two-dimensional vanadium oxide A3;

[0100] (3) The suspension obtained in step (2) was centrifuged using a high-speed centrifuge at 2000 rpm for 10 min and dried at 80° C. for 24 h to obtain 2 mg of two-dimensional vanadium oxide A3 with a yield of 20%.

[0101] A3 was observed using AFM. From the AFM photos obtained, it can be seen that the thickness of A3 is relatively uniform, ranging from 1.2 to 2.8 nm.

[0102] A3 was observed using TEM. From the obtained TEM photos, it can be seen that A3 has good lamella integrity and no obvious damage.

[0103] A3 was tested using EDS. From the energy spectrum of each element in A3, it can be seen that the elements in A3 are vanadium and oxygen, and there is no chlorine element. A3 is vanadium oxide.

[0104] A3 was tested using photoelectron spectroscopy. From the obtained spectrum, it can be seen that the vanadium ions in A3 are V +5 , so A3 is vanadium pentoxide.

[0105] Example 4

[0106] A method for preparing a two-dimensional vanadium oxide A4 comprises the following steps:

[0107] (1) 10 mg of VOCl was wrapped with a stainless steel mesh and clamped on the electrode clamp of the electrolytic cell. The counter electrode was a graphite electrode. The negative electrode and the counter electrode were immersed in an electrolyte solution of tetramethylammonium bromide in acetonitrile with a concentration of 0.05 mol / L. The electrolyte was electrolyzed at a voltage of 10 V for 20 min to obtain an intercalated two-dimensional vanadium oxide.

[0108] (2) After the electrolysis is completed, the intercalated two-dimensional metal oxide obtained in step (1) is washed with deionized water, then immersed in deionized water, and ultrasonically dispersed at 100 W for 30 minutes to obtain a suspension containing the two-dimensional vanadium oxide A4;

[0109] (3) The suspension obtained in step (2) was centrifuged using a high-speed centrifuge at 1000 rpm for 10 min and dried at 80° C. for 24 h to obtain 1 mg of two-dimensional vanadium oxide A4 with a yield of 10%.

[0110] A4 was observed using AFM. From the AFM photos obtained, it can be seen that the thickness of A4 is relatively uniform, ranging from 2 to 4 nm.

[0111] A4 was observed using TEM. From the obtained TEM photos, it can be seen that A4 has good lamella integrity and no obvious damage.

[0112] A4 was tested using EDS. From the energy spectrum of each element in A4, it can be seen that the elements in A4 are vanadium and oxygen, and there is no chlorine element. A4 is vanadium oxide.

[0113] A4 was tested using photoelectron spectroscopy. From the obtained spectrum, it can be seen that the vanadium ions in A4 are V +5 , so A4 is vanadium pentoxide.

[0114] Application Example 1

[0115] (1) The two-dimensional vanadium oxide A1 prepared in Example 1 was mixed with conductive carbon black SuperP and polyvinylidene fluoride (PVDF) in a mass ratio of 4:5:1 in an appropriate amount of 2 ml of N-methylpyrrolidone (NMP), and ground to obtain a slurry;

[0116] (2) The slurry obtained in step (1) is evenly coated on the matte surface of an aluminum foil by a doctor blade method, and the aluminum foil is placed in an oven and vacuum-dried at 60° C. for 12 h to completely evaporate the NMP solvent to obtain a positive electrode sheet;

[0117] (3) Assembling the positive electrode sheet obtained in step (2) together with the electrode shell, the positive electrode sheet, the separator (stripped fiber), the electrolyte (1M LiPF6 diethyl carbonate (DEC) and ethylene carbonate (EC) solution, wherein the volume ratio of DEC to EC is 1:1), the gasket, the spring, and the metal lithium sheet to obtain a button battery I;

[0118] The battery was tested for cyclic voltammetry in the voltage range of 2V and 3.7V. The obtained cyclic voltammetry curve is as follows: Figure 6 As shown in Figure 1, the reason for selecting this voltage range is to avoid irreversible structural changes in the electrode material and to prevent electrochemical reactions in the battery shell or electrolyte. Figure 6 It can be seen that the redox process of the two-dimensional vanadium oxide material shows only a set of redox peaks at 2.53V / 2.67V. XPS characterization of the electrode materials at different discharge stages is carried out to determine the charge transfer process occurring in this voltage range. The characterization results are shown in Figure 2. Figure 7 As shown, from Figure 7 It can be seen that in the voltage range of 2V and 3.7V, the two-dimensional vanadium oxide only undergoes V 5+ / V 4+ The redox conversion between the two-dimensional vanadium oxide and the V 4+ The ratio gradually increases and eventually exceeds V 5+ proportion.

[0119] Application Example 2

[0120] The same method as in Application Example 1 was used to apply A4 prepared in Example 4 to the preparation of the positive electrode material, and the assembly of Battery II was completed.

[0121] Under the condition of current density of 0.5mA / g, the specific capacity of battery I and battery II is compared. The results are as follows: Figure 8 As shown, from Figure 8 It can be seen that during 100 charge-discharge cycles, the specific capacity of Battery II is smaller than that of Battery I. This is because the smaller the thickness of the two-dimensional vanadium oxide, the larger the specific surface area of ​​the material, which can provide more surface reaction sites for lithium ions, thereby improving the specific capacity of the battery. In addition, the present invention still has a high specific capacity after 100 cycles, indicating that the two-dimensional vanadium oxide prepared by the present invention has good stability.

[0122] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a two-dimensional vanadium oxide, characterized in that: The method specifically comprises the following steps: (1) The parent material is used as the negative electrode, and the negative electrode and the counter electrode are immersed in an electrolyte to perform an electrochemical reaction to obtain an intercalated two-dimensional vanadium oxide; (2) peeling off the intercalated two-dimensional vanadium oxide obtained in step (1) to obtain the two-dimensional vanadium oxide; Wherein, the matrix material is a van der Waals layered vanadium compound.

2. The method according to claim 1, characterized in that The matrix material is VOCl.

3. The method according to claim 1, characterized in that The electrolyte contains quaternary ammonium salt.

4. The method according to claim 3, characterized in that The quaternary ammonium salt is selected from one or more of tetramethylammonium bromide, tetraethylammonium bromide, tetrabutylammonium bromide and tetrahexylammonium bromide.

5. The method according to claim 1, characterized in that In step (1), the voltage of the electrochemical reaction is 2-15V, and the time is 10min-1h.

6. The method according to claim 1, characterized in that In step (2), the stripping is to add the intercalated two-dimensional vanadium oxide obtained in step (1) into a solvent for dispersion.

7. The method according to claim 6, characterized in that The solvent is a polar solvent, preferably at least one selected from deionized water, N-methylpyrrolidone, and methanol.

8. A two-dimensional vanadium oxide, characterized in that The two-dimensional vanadium oxide is prepared by the method according to any one of claims 1 to 7.

9. Application of a two-dimensional vanadium oxide in an ion battery electrode material, characterized in that: The two-dimensional vanadium oxide is prepared by the method according to any one of claims 1 to 7.

10. A positive electrode material for a lithium ion battery, characterized in that: The lithium-ion battery positive electrode material comprises a two-dimensional vanadium oxide, wherein the two-dimensional vanadium oxide is prepared by the method according to any one of claims 1 to 7.

Images