A VO2 nanobelt-based composite material and its preparation method, and zinc ion battery

Abstract

The present invention provides a VO2 nanobelt-based composite material and a preparation method thereof, as well as a zinc ion battery. The preparation method provided by the present invention comprises: a) converting V6O 13 The nanobelt dispersion and the transition metal salt solution are mixed, and then the solid-liquid separation is performed to obtain an intermediate; the V6O 13 Nanobelt dispersion includes: V6O 13 Nanobelts, a surfactant, and a dispersant; the transition metal salt solution is a solution of a soluble transition metal salt dissolved in a solvent; b) mixing the intermediate with a nitrogen-containing organic compound and a saccharide to obtain a mixture; or dispersing the intermediate in a dispersant to obtain a dispersion, which is then mixed with the nitrogen-containing organic compound and a saccharide to obtain a mixture; c) calcining the mixture to obtain a VO2 nanobelt-based composite material. The VO2 nanobelt-based composite material provided by the present invention can improve the discharge capacity and electrochemical cycle stability of a battery.

Description

Technical Field

[0001] The present invention relates to the field of energy, and in particular to a VO2 nanobelt-based composite material and a preparation method thereof, as well as a zinc ion battery. Background Art

[0002] Aqueous zinc-ion batteries (AZIBs) have attracted widespread attention as next-generation batteries due to their low cost, high safety, low anode potential, and high theoretical capacity. Despite these advantages, the performance of AZIBs is still far from practical application, including low discharge capacity, low operating voltage, narrow potential window, dendrite growth, and side reactions. Recent studies have shown that vanadium oxide-based cathode materials exhibit high capacity and good stability during cycling due to their multivalent states and layered or tunnel-like structures. Currently, the design and synthesis of cathode materials for AZIBs are still in their infancy, and the rational design of cathodes requires further exploration in the future.

[0003] However, the intercalation / deintercalation of divalent zinc ions in the cathode crystal structure usually leads to irreversible phase transitions, structural degradation, and kinetic sluggishness, resulting in poor capacity. Therefore, in order to improve the kinetics, researchers have designed various strategies to optimize vanadium oxide-based cathodes, hybridize vanadium oxide with other active materials, or prepare amorphous vanadium oxide-based cathodes. However, in actual research and development applications, due to problems such as differences in matching and adaptability between different substances, how to truly make vanadium oxide-based materials with good electrochemical performance still faces great difficulties. Summary of the Invention

[0004] In view of this, the present invention provides a VO2 nanobelt-based composite material and a preparation method thereof, as well as a zinc ion battery. The VO2 nanobelt-based composite material provided by the present invention can improve the discharge capacity and electrochemical cycle stability of the battery.

[0005] The present invention provides a method for preparing a VO2 nanobelt-based composite material, comprising the following steps:

[0006] a) V6O 13 The nanobelt dispersion and the transition metal salt solution are mixed, and then the solid-liquid separation is performed to obtain an intermediate;

[0007] The V6O 13 Nanobelt dispersion includes: V6O 13 nanoribbons, surfactants, and dispersants;

[0008] The transition metal salt solution is a solution obtained by dissolving a soluble transition metal salt in a solvent;

[0009] b) mixing the intermediate with nitrogen-containing organic matter and sugars to obtain a mixture;

[0010] or

[0011] Dispersing the intermediate in a dispersant to obtain a dispersion, and then mixing it with nitrogen-containing organic matter and sugars to obtain a mixture;

[0012] c) calcining the mixture to obtain a VO2 nanobelt-based composite material.

[0013] Preferably, the transition metal in the transition metal salt is cobalt;

[0014] The transition metal salt is at least one of nitrate, acetate, chloride, acetylacetonate and sulfate.

[0015] Preferably, in step a), the V6O 13 V6O in nanobelt dispersion 13 The usage ratio of the nanobelt to the transition metal salt in the transition metal salt solution is 50 mg: (0.1-10) mol.

[0016] Preferably, the nitrogen-containing organic compound is at least one of an amine organic compound, a nitrogen heterocyclic organic compound, a nitrile organic compound, and an amide organic compound;

[0017] The amine organic compound is at least one of dicyandiamide, methylamine, aniline, ethylenediamine, diisopropylamine and triethanolamine;

[0018] The nitrogen heterocyclic organic compound is 1H-aza at least one of imidazole, quinoline, and pteridine;

[0019] The nitrile organic compound is at least one of hydrogen cyanide and cyanide gas;

[0020] The amide organic compound is at least one of caprolactam, polyacrylamide, N,N-dimethylformamide and erucamide;

[0021] The mass ratio of the intermediate to the nitrogen-containing organic matter is 1:(0.1-100).

[0022] Preferably, the sugar is at least one of glucose, fructose, galactose, ribose, sucrose, lactose, maltose, starch, glycogen, cellulose structure, chitin, inulin and agar;

[0023] The mass ratio of the intermediate to the sugar is 1:(0.001-100).

[0024] Preferably, the surfactant is at least one of polyacrylamide, polyacrylic acid, polyvinyl pyrrolidone, polyvinyl alcohol, polymaleic anhydride, polyquaternary ammonium salt and polyethylene glycol;

[0025] The V6O 13The dispersant in the nanobelt dispersion is at least one of methanol, ethanol, propanol, isopropanol, butanol, pentanol, benzene, phenol, toluene, N,N-dimethylformamide and water;

[0026] The V6O 13 V6O in nanobelt dispersion 13 The concentration of the nanobelt is 1 to 1000 mg / mL; the V6O 13 The concentration of the surfactant in the nanobelt dispersion is 0.01 to 200 mg / mL.

[0027] Preferably, in step c), the calcination temperature is 200-1200° C., and the holding time is 0.1-120 h.

[0028] Preferably, in step c), drying is performed before calcining;

[0029] The drying temperature is 30-200°C.

[0030] The present invention also provides a VO2 nanobelt-based composite material prepared by the preparation method described in the above technical solution.

[0031] The present invention also provides a zinc ion battery, wherein the cathode active material on the cathode sheet is the VO2 nanobelt-based composite material described in the above technical solution.

[0032] The preparation method provided by the present invention comprises the following steps: firstly 13 The nanobelt dispersion and the transition metal salt solution are mixed and solid-liquid separated to obtain an intermediate; then, the intermediate is mixed with nitrogen-containing organic matter and sugar (or the intermediate is dispersed in a dispersant to obtain a dispersion, and then mixed with nitrogen-containing organic matter and sugar) to obtain a mixture; finally, calcination is performed to obtain a VO2 nanobelt-based composite material. In the above preparation process, in the first step, the surfactant combines with V6O 13 Nanobelts and transition metals in transition metal salts. In the last two steps, sugars and nitrogen-containing organic matter are heated and dehydrated to form NC structures, which are then calcined to form VO2 nanobelt materials containing transition metal single atoms and carbon-coated VO2 nanobelts. The final VO2 nanobelt-based composite material is based on VO2 nanobelts, which are coated with a layer of transition metal single atoms and N-doped carbon coating. 13Nanobelt one-dimensional metal inorganic material is used as a template to induce the generation of another one-dimensional metal inorganic material (i.e., VO2 nanobelt material). Compared with VO2 nanobelt materials prepared by other methods (such as hydrothermal method, etc.), the present invention adopts the above-mentioned specific method to prepare VO2 nanobelt material as a matrix, which can improve the mobility of zinc ions and thus improve the conductivity of zinc ion batteries. Moreover, the present invention constructs an interface between VO2 nanobelt material and MNC, which is conducive to the storage of zinc ions and improves the battery capacity. The composite material obtained by the method of the present invention can maintain stability during the discharge process, thereby improving the battery recycling performance. In addition, the preparation method of the present invention is simple to operate, does not require complex equipment, has mild conditions, is easy to obtain template materials, has a controllable process, and has a wide range of raw materials, which is conducive to industrialization.

[0033] The test results show that the VO2 nanobelt-based composite material provided by the present invention can still enable the battery discharge capacity to reach above 370 mAh / g after 200 cycles, showing excellent discharge capacity and electrochemical cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0035] Figure 1 This is the SEM image of the VO2 nanobelt-based composite material obtained in Example 1;

[0036] Figure 2 TEM image of the VO2 nanobelt-based composite material obtained in Example 1;

[0037] Figure 3 This is the XRD pattern of the VO2 nanobelt-based composite material obtained in Example 1;

[0038] Figure 4 This is a graph showing the cycling stability of the VO2 nanobelt-based composite material obtained in Example 1 as a cathode material for a zinc ion battery at a current density of 1 A / g;

[0039] Figure 5 This is the SEM image of the VO2 nanobelt-based composite material obtained in Comparative Example 1;

[0040] Figure 6 TEM image of the VO2 nanobelt-based composite material obtained in Comparative Example 1;

[0041] Figure 7 This is the XRD pattern of the VO2 nanobelt-based composite material obtained in Comparative Example 1;

[0042] Figure 8 This is a cycle stability curve of the VO2 nanobelt-based composite material obtained in Comparative Example 1 at a current density of 1 A / g when used as a cathode material for a zinc ion battery;

[0043] Figure 9 This is the SEM image of the VO2 nanobelt-based composite material obtained in Comparative Example 2;

[0044] Figure 10 TEM image of the VO2 nanobelt-based composite material obtained in Comparative Example 2;

[0045] Figure 11 This is the XRD pattern of the VO2 nanobelt-based composite material obtained in Comparative Example 2;

[0046] Figure 12 This is a cycle stability curve of the VO2 nanobelt-based composite material obtained in Comparative Example 2 at a current density of 1 A / g when used as a cathode material for a zinc ion battery. DETAILED DESCRIPTION

[0047] The present invention provides a method for preparing a VO2 nanobelt-based composite material, comprising the following steps:

[0048] a) V6O 13 The nanobelt dispersion and the transition metal salt solution are mixed, and then the solid-liquid separation is performed to obtain an intermediate;

[0049] The V6O 13 Nanobelt dispersion includes: V6O 13 nanoribbons, surfactants, and dispersants;

[0050] The transition metal salt solution is a solution obtained by dissolving a soluble transition metal salt in a solvent;

[0051] b) mixing the intermediate with nitrogen-containing organic matter and sugars to obtain a mixture;

[0052] or

[0053] Dispersing the intermediate in a dispersant to obtain a dispersion, and then mixing it with nitrogen-containing organic matter and sugars to obtain a mixture;

[0054] c) calcining the mixture to obtain a VO2 nanobelt-based composite material.

[0055] Regarding step a) :

[0056] a) V6O 13 The nanobelt dispersion and the transition metal salt solution are mixed, and then the solid and liquid are separated to obtain an intermediate.

[0057] In the present invention, the V6O 13 Nanobelt dispersion includes: V6O 13 Nanobelts, surfactants and dispersants. 13 There is no special restriction on the preparation method of nanobelt dispersion. The above materials can be evenly mixed and dispersed. For example, V6O 13 Nanobelts and surfactants are dispersed in a dispersant to obtain V6O 13 Nanoribbon dispersion.

[0058] in:

[0059] The V6O 13 The source of the nanobelts is not particularly limited and can be prepared according to conventional preparation methods in the art; preferably, the V6O 13 The nanobelts can be prepared according to the preparation method disclosed in the paper "Crystal water enlarging the interlayer spacing of ultrathin V2O5·4VO2·2.72H2O nanobelts for high-performance aqueous zinc-ion battery" published by our research group in the Journal of Chemical Engineering, Vol. 411, No. 128533 in 2021. Those skilled in the art can select and adjust the V6O5·4VO2·2.72H2O nanobelts according to actual application conditions, raw material conditions and product requirements. 13 The thickness of the nanobelt can specifically be 0.2 to 100 nm, 1.0 to 80 nm, 2.0 to 60 nm, 5.0 to 60 nm, and optimally 30 to 40 nm.

[0060] The surfactant is preferably at least one of polyacrylamide, polyacrylic acid, polyvinyl pyrrolidone, polyvinyl alcohol, polymaleic anhydride, polyquaternary ammonium salt and polyethylene glycol.

[0061] The dispersant is preferably at least one of methanol, ethanol, propanol, isopropanol, butanol, pentanol, benzene, phenol, toluene, N,N-dimethylformamide and water.

[0062] The V6O 13 V6O in nanobelt dispersion 13 The concentration of the nanobelt is preferably 1 to 1000 mg / mL, specifically 1 mg / mL, 5 mg / mL, 10 mg / mL, 100 mg / mL, and 1000 mg / mL. 13The concentration of the surfactant in the nanobelt dispersion is preferably 0.01 to 200 mg / mL, more preferably 0.01 to 100 mg / mL, further preferably 0.01 to 50 mg / mL, and most preferably 0.01 to 20 mg / mL.

[0063] In the present invention, the transition metal salt solution is a solution obtained by dissolving a soluble transition metal salt in a solvent.

[0064] in:

[0065] The transition metal in the soluble transition metal salt is preferably cobalt (Co). The salt type of the soluble transition metal salt is preferably at least one of nitrate, acetate, chloride, acetylacetonate and sulfate, more preferably at least one of nitrate, acetate and chloride, and most preferably chloride.

[0066] The solvent is preferably at least one of water, methanol, ethanol, acetone, propanol, isopropanol, n-butanol, isobutanol, pentanol, methylamine, ethylamine, propylamine, N,N-dimethylformamide, benzene and phenol; more preferably at least one of water, methanol, ethanol, acetone and propanol; most preferably water.

[0067] The concentration of the transition metal salt solution is preferably 0.001 to 10 mol / L, more preferably 0.001 to 5 mol / L, further preferably 0.001 to 1 mol / L, and most preferably 0.001 to 0.1 mol / L.

[0068] In the present invention, V6O 13 When the nanobelt dispersion and transition metal salt solution are mixed, the V6O 13 V6O in nanobelt dispersion 13 The amount ratio of the nanobelts to the transition metal salt in the transition metal salt solution is preferably 50 mg: (0.1-10) mol, specifically 50 mg: 0.1 mol, 50 mg: 0.5 mol, 50 mg: 1.0 mol, 50 mg: 5 mol, 50 mg: 10 mol. In the present invention, the mixing method is preferably stirring mixing. The stirring temperature condition is preferably 0-100°C. The stirring rate is preferably 1-2000 pm. The stirring time is preferably 0.5-100 h, more preferably 0.5-60 h, further preferably 0.5-40 h, and most preferably 0.5-24 h. After the above mixing treatment, a uniformly mixed mixture is obtained.

[0069] In the present invention, after the above mixing treatment, solid-liquid separation is performed. In the present invention, the solid-liquid separation method is preferably centrifugal separation. In the present invention, after the above solid-liquid separation, an intermediate is obtained.

[0070] Regarding step b) :

[0071] b) mixing the intermediate with a nitrogen-containing organic compound and a sugar to obtain a mixture; or dispersing the intermediate in a dispersant to obtain a dispersion, and then mixing the dispersion with the nitrogen-containing organic compound and the sugar to obtain a mixture.

[0072] In the present invention, after the intermediate is obtained in step a), there are two ways to obtain a mixture with the nitrogen-containing organic matter and the sugar: the first is to directly mix the intermediate with the nitrogen-containing organic matter and the sugar to obtain a mixture; the second is to first disperse the intermediate in a dispersant to obtain a dispersion, and then mix the dispersion with the nitrogen-containing organic matter and the sugar to obtain a mixture.

[0073] In the present invention, the nitrogen-containing organic compound is preferably at least one of an amine organic compound, a nitrogen heterocyclic organic compound, a nitrile organic compound and an amide organic compound. Among them, the amine organic compound is preferably at least one of dicyandiamide, methylamine, aniline, ethylenediamine, diisopropylamine and triethanolamine. The nitrogen heterocyclic organic compound is preferably 1H-aza At least one of imidazole, quinoline, and pteridine. The nitrile organic compound is preferably at least one of hydrogen cyanide and cyanide gas. The amide organic compound is preferably at least one of caprolactam, polyacrylamide, N,N-dimethylformamide, and erucamide. In the present invention, the mass ratio of the intermediate to the nitrogen-containing organic compound is preferably 1:(0.1-100), more preferably 1:(0.1-10), and most preferably 1:(1-2).

[0074] In the present invention, the sugar (i.e., organic carbohydrate) is preferably at least one of glucose, fructose, galactose, ribose, sucrose, lactose, maltose, starch, glycogen, cellulose structure, chitin, inulin, and agar; more preferably at least one of glucose, fructose, galactose, and ribose; and most preferably glucose. In the present invention, the mass ratio of the intermediate to the sugar is preferably 1:(0.001-100), more preferably 1:(0.01-10), and most preferably 1:(0.1-1).

[0075] In the present invention, the dispersant is preferably at least one of alcohol, methanol, ethanol, propanol, isopropanol, butanol, amyl alcohol and benzene. In the present invention, the amount ratio of the intermediate to the dispersant is preferably (50-500) mg: 2 mL, specifically 50 mg: 2 mL, 100 mg: 2 mL, 200 mg: 2 mL, 250 mg: 2 mL, 300 mg: 2 mL, 400 mg: 2 mL, 500 mg: 2 mL. In the present invention, the method for dispersing the intermediate in the dispersant is not particularly limited, and any conventional method for dispersing materials in the art, such as ultrasonic dispersion, can be used.

[0076] In the present invention, the mixing method is not particularly limited, and the materials can be mixed uniformly according to conventional mixing methods well known to those skilled in the art, such as stirring. The above treatment is performed to obtain a uniform mixture.

[0077] Regarding step c) :

[0078] c) calcining the mixture to obtain a VO2 nanobelt-based composite material.

[0079] In the present invention, drying is preferably performed before calcining, and the drying temperature is preferably 30-200°C, specifically 30°C, 50°C, 80°C, 100°C, 150°C, or 200°C.

[0080] In the present invention, the calcination is preferably carried out under a protective atmosphere. The present invention has no particular limitation on the type of gas providing the protective atmosphere, and any conventional protective gas known to those skilled in the art can be used, such as nitrogen or argon, more preferably argon.

[0081] In the present invention, the calcination temperature is preferably 200-1200°C, specifically 200°C, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, or 1200°C. The heating rate of the calcination is preferably 0.1-50°C / min, more preferably 0.1-20°C / min, and most preferably 0.1-5°C / min. The holding time of the calcination is preferably 0.1-120h, more preferably 0.1-10h. After the calcination, a VO2 nanobelt-based composite material is obtained.

[0082] The present invention also provides a VO2 nanobelt-based composite material prepared by the preparation method described in the above technical solution. In the preparation method provided by the present invention, in the first step, a surfactant is combined with V6O 13 Nanobelts and transition metals in transition metal salts. In the last two steps, sugars and nitrogen-containing organic matter are heated and dehydrated to form NC structures, which are then calcined to form VO2 nanobelt materials containing transition metal single atoms and carbon-coated VO2 nanobelts. The final VO2 nanobelt-based composite material is based on VO2 nanobelts, which are coated with a layer of transition metal single atoms and N-doped carbon coating. It can be recorded as VO2@MNC composite material, where M represents a transition metal single atom, N represents a nitrogen atom, and C represents carbon. In the present invention, the thickness of the nanosheets in the obtained VO2 nanobelt-based composite material is ≤100nm, preferably ≤50nm, more preferably ≤20nm, and most preferably ≤10nm.

[0083] The present invention also provides a cathode sheet, wherein the active material is the VO2 nanobelt-based composite material described in the above technical solution.

[0084] The present invention also provides a zinc ion battery, wherein the cathode active material on the cathode sheet is the VO2 nanobelt-based composite material described in the above technical solution.

[0085] The preparation method provided by the present invention comprises the following steps: firstly 13 The nanobelt dispersion and the transition metal salt solution are mixed and solid-liquid separated to obtain an intermediate; then, the intermediate is mixed with nitrogen-containing organic matter and sugar (or the intermediate is dispersed in a dispersant to obtain a dispersion, and then mixed with nitrogen-containing organic matter and sugar) to obtain a mixture; finally, calcination is performed to obtain a VO2 nanobelt-based composite material. In the above preparation process, in the first step, the surfactant combines with V6O 13 Nanobelts and transition metals in transition metal salts. In the last two steps, sugars and nitrogen-containing organic matter are heated and dehydrated to form NC structures, which are then calcined to form VO2 nanobelt materials containing transition metal single atoms and carbon-coated VO2 nanobelts. The final VO2 nanobelt-based composite material is based on VO2 nanobelts, which are coated with a layer of transition metal single atoms and N-doped carbon coatings. It can be recorded as VO2@MNC composite material, where M represents a transition metal single atom, N represents a nitrogen atom, and C represents carbon. The present invention utilizes V6O 13 Nanobelt one-dimensional metal inorganic material is used as a template to induce the generation of another one-dimensional metal inorganic material (i.e., VO2 nanobelt material). Compared with VO2 nanobelt materials prepared by other methods, the present invention adopts the above-mentioned specific method to prepare VO2 nanobelt material as a matrix, which can improve the mobility of zinc ions and improve the conductivity of zinc ion batteries. Moreover, the present invention constructs the interface between VO2 nanobelt material and MNC. The nitrogen-doped and transition metal single-atom dispersed carbon material layer exhibits a special electronic structure, dense active sites, high special areas and good stability, forming a certain interface with the VO2 nanobelt material, which is conducive to the storage of zinc ions and improves the battery capacity. The composite material obtained by the method of the present invention can maintain stability during the discharge process and improve the battery recycling performance. In addition, the preparation method of the present invention is simple to operate, does not require complex equipment, has mild conditions, is easy to obtain template materials, has a controllable process, and has a wide source of raw materials, which is conducive to industrialization.

[0086] The test results show that the VO2 nanobelt-based composite material provided by the present invention can still enable the battery discharge capacity to reach above 370 mAh / g after 200 cycles, showing excellent discharge capacity and electrochemical cycle stability.

[0087] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0088] In the following examples, unless otherwise specified, the drugs and reagents used were commercially available, mainly purchased from Sinopharm Chemical Reagent Co., Ltd. 13 The nanoribbons were prepared according to the preparation method mentioned above.

[0089] Example 1

[0090] 1. Sample preparation

[0091] a) Add 50 mg of V6O 13 Nanobelts and 200 mg of polyvinyl pyrrolidone were dispersed in 5 mL of pure water to obtain V6O 13 Nanobelt dispersion. V6O 13 The nanobelt dispersion was stirred and mixed with a CoCl2 aqueous solution (5 mL, 0.1 mol / L) for 24 h, and then centrifuged to obtain an intermediate.

[0092] b) The obtained intermediate was dispersed in 2 mL of alcohol to obtain a dispersion, and then 5 mg of glucose and 100 mg of dicyandiamide were added and mixed uniformly to obtain a mixture.

[0093] c) The obtained mixture was dried at 80° C. for 24 h, and then raised to 600° C. at a rate of 5° C. / min in an argon atmosphere and calcined for 2 h to obtain a VO2 nanobelt-based composite material.

[0094] 2. Sample characterization and testing

[0095] (1) SEM and TEM characterization

[0096] The obtained VO2 nanobelt-based composite material was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Figure 1-2 As shown, Figure 1 This is the SEM image of the VO2 nanobelt-based composite material obtained in Example 1. Figure 2 This is a TEM image of the VO2 nanobelt-based composite material obtained in Example 1. It can be seen that the VO2 nanobelt coated with nitrogen-doped carbon containing cobalt single atoms obtained in Example 1 has a width of about 200 nm and a length of about several microns.

[0097] (2) XRD characterization

[0098] The phase analysis of the obtained VO2 nanobelt-based composite material was carried out using an X-ray diffraction (XRD) instrument. The results are as follows: Figure 3 As shown, Figure 3 : This is the XRD pattern of the VO2 nanobelt-based composite material obtained in Example 1. It can be seen that the diffraction peaks of the cobalt-containing single-atom nitrogen-doped carbon-coated VO2 nanobelt composite material obtained in Example 1 are consistent with the diffraction peak characteristics of the VO2 phase.

[0099] (3) Electrochemical performance test

[0100] The VO2 nanobelt-based composite material obtained in Example 1, superphosphorus carbon, and polyvinylidene fluoride (PVDF) binder were mixed in N-methylpyrrolidone solvent at a mass ratio of 7:2:1 to obtain a positive electrode slurry. The obtained positive electrode slurry was evenly coated on a titanium foil with a thickness of 20 microns. After being placed in a vacuum oven for 8 hours to dry, the active material loading mass on the titanium foil surface was 1.5 mg / cm 2 , and obtain the cathode sheet. At the same time, the zinc sheet was used as the anode sheet, and the zinc trifluoromethanesulfonate solution (concentration 3 mol / L, solvent is deionized water) was used as the electrolyte to assemble a zinc ion battery. The cycle stability of the zinc ion battery was tested, and the results were as follows Figure 4 As shown in the figure, at a current density of 1 A / g, the discharge capacity reached 296.1 mAh / g in the first cycle, reaching a maximum of 421.5 mAh / g after 60 cycles, and maintaining a discharge capacity of 376.7 mAh / g after 200 cycles. These test results demonstrate that the cobalt-containing single-atom nitrogen-doped carbon-coated VO2 nanobelt composite material obtained in this invention exhibits excellent electrochemical performance when used as a cathode material.

[0101] Comparative Example 1

[0102] 1. Sample preparation

[0103] The process was carried out in accordance with Example 1, except that no CoCl2 aqueous solution was added in step a).

[0104] 2. Sample characterization and testing

[0105] (1) SEM and TEM characterization

[0106] The obtained carbon-coated VO2 nanobelt composite material was analyzed by scanning electron microscopy and transmission electron microscopy. Figure 5-6 As shown, Figure 5 This is the SEM image of the VO2 nanobelt-based composite material obtained in Comparative Example 1. Figure 6 This is a TEM image of the VO2 nanobelt-based composite material obtained in Comparative Example 1. It can be seen that the carbon-coated VO2 nanobelt obtained in Comparative Example 1 has a width of about 200 nm and a length of about several microns.

[0107] (2) XRD characterization

[0108] The obtained carbon-coated VO2 nanobelt composite material was analyzed by X-ray diffraction (XRD) instrument. Figure 7 As shown, Figure 7 : This is the XRD pattern of the VO2 nanobelt-based composite material obtained in Comparative Example 1. It can be seen that the diffraction peaks of the carbon-coated VO2 nanobelt composite material obtained in Comparative Example 1 are consistent with the diffraction peak characteristics of the VO2 phase.

[0109] (3) Electrochemical performance test

[0110] The battery was assembled and electrochemical performance tested according to the method in Example 1. The results are as follows: Figure 8 For specific data, see Table 1.

[0111] Comparative Example 2

[0112] 1. Sample preparation

[0113] The process was carried out in accordance with Example 1, except that the transition metal salt solution in step a) was adjusted to a CoCl2 aqueous solution (3 mL, 0.1 mol / L) and a NiCl2 aqueous solution (2 mL, 0.1 mol / L).

[0114] 2. Sample characterization and testing

[0115] (1) SEM and TEM characterization

[0116] The obtained VO2 nanobelt composite material containing cobalt and nickel single atom carbon coated was analyzed by scanning electron microscopy and transmission electron microscopy. Figure 9-10 As shown, Figure 9 This is the SEM image of the VO2 nanobelt-based composite material obtained in Comparative Example 2. Figure 10 This is a TEM image of the VO2 nanobelt-based composite material obtained in Comparative Example 2. It can be seen that the VO2 nanobelt-based composite material obtained in Comparative Example 2 has a width of about 200 nm and a length of about several microns.

[0117] (2) XRD characterization

[0118] The composite material was analyzed by X-ray diffraction (XRD). Figure 11 As shown, Figure 11 This is the XRD pattern of the VO2 nanobelt-based composite material obtained in Comparative Example 2. It can be seen that the diffraction peaks of the carbon-coated VO2 nanobelt composite material obtained in Comparative Example 2 are consistent with the diffraction peak characteristics of the VO2 phase.

[0119] (3) Electrochemical performance test

[0120] The battery was assembled and electrochemical performance tested according to the method in Example 1. The results are as follows: Figure 12 For specific data, see Table 1.

[0121] Table 1: Electrochemical performance test results of Examples and Comparative Examples

[0122]

[0123] It can be seen from the test results in Table 1 that the discharge capacity of the nitrogen-doped carbon-coated VO2 nanobelt composite material containing cobalt single atoms obtained in Example 1 can still be maintained at 376.7mAh / g after 200 cycles, showing excellent cycle stability. Compared with Example 1, Comparative Example 1 does not introduce transition metals, and the electrochemical performance of the material decreases significantly, proving that the cobalt atoms in the carbon layer are beneficial to improving the electrochemical performance of the material. Compared with Example 1, Comparative Example 2 introduces transition metals Co and Ni at the same time, and the electrochemical performance of the material decreases significantly, proving that the introduction of Co single atoms in the composite material system of the present invention is helpful to improve the electrochemical performance of the composite material, while the introduction of Ni single atoms is not conducive to improving its electrochemical stability, indicating that in the composite material system of the present invention, specific transition metal atoms are combined with other components to improve the electrochemical performance of the composite material.

[0124] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal description of the claims, or if they include equivalent structural elements that are not substantially different from the literal description of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for preparing a VO2 nanobelt-based composite material, characterized in that: The following steps are involved: a) V6O 13 The nanobelt dispersion and the transition metal salt solution are mixed, and then the solid-liquid separation is performed to obtain an intermediate; The V6O 13 Nanobelt dispersion includes: V6O 13 nanoribbons, surfactants, and dispersants; The transition metal salt solution is a solution obtained by dissolving a soluble transition metal salt in a solvent; The transition metal in the soluble transition metal salt is cobalt; b) mixing the intermediate with a nitrogen-containing organic compound and a sugar to obtain a mixture; or Dispersing the intermediate in a dispersant to obtain a dispersion, and then mixing it with nitrogen-containing organic matter and sugars to obtain a mixture; c) calcining the mixture to obtain a VO2 nanobelt-based composite material.

2. The preparation method according to claim 1, characterized in that The transition metal salt is at least one of nitrate, acetate, chloride, acetylacetonate and sulfate.

3. The preparation method according to claim 1, characterized in that In step a), the V6O 13 V6O in nanobelt dispersion 13 The dosage ratio of the nanobelt to the transition metal salt in the transition metal salt solution is 50 mg: (0.1-10) mol.

4. The preparation method according to claim 1, characterized in that The nitrogen-containing organic compound is at least one of an amine organic compound, a nitrogen heterocyclic organic compound, a nitrile organic compound, and an amide organic compound; The amine organic compound is at least one of dicyandiamide, methylamine, aniline, ethylenediamine, diisopropylamine and triethanolamine; The nitrogen heterocyclic organic compound is at least one of 1H-azaphene, imidazole, quinoline and pteridine; The nitrile organic compound is at least one of hydrogen cyanide and cyanide gas; The amide organic compound is at least one of caprolactam, polyacrylamide, N,N-dimethylformamide and erucamide; The mass ratio of the intermediate to the nitrogen-containing organic matter is 1:(0.1-100).

5. The preparation method according to claim 1, characterized in that The sugar is at least one of glucose, fructose, galactose, ribose, sucrose, lactose, maltose, starch, glycogen, cellulose, chitin, inulin and agar; The mass ratio of the intermediate to the sugar is 1:(0.001-100).

6. The preparation method according to claim 1, characterized in that The surfactant is at least one of polyacrylamide, polyacrylic acid, polyvinyl pyrrolidone, polyvinyl alcohol, polymaleic anhydride, polyquaternary ammonium salt and polyethylene glycol; The V6O 13 The dispersant in the nanobelt dispersion is at least one of methanol, ethanol, propanol, isopropanol, butanol, pentanol, benzene, phenol, toluene, N,N-dimethylformamide and water; The V6O 13 V6O in nanobelt dispersion 13 The concentration of the nanobelts is 1-1000 mg / mL; the V6O 13 The concentration of the surfactant in the nanobelt dispersion was 0.01~200 mg / mL.

7. The preparation method according to claim 1, characterized in that In step c), the calcination temperature is 200-1200° C., and the holding time is 0.1-120 h.

8. The preparation method according to claim 1, characterized in that In step c), drying is performed before calcining; The drying temperature is 30-200°C.

9. A VO2 nanobelt-based composite material obtained by the preparation method according to any one of claims 1 to 8.

10. A zinc ion battery, characterized in that: The cathode active material on the cathode sheet is the VO2 nanobelt-based composite material as described in claim 9.

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