Graphene supported vanadium monatomic sulfur fixation catalyst and application thereof

Abstract

The application belongs to the technical field of batteries, and particularly relates to a graphene-supported vanadium monatomic sulfur-fixing catalyst and application. The preparation method of the graphene-supported vanadium monatomic sulfur-fixing catalyst comprises the following steps: (1) mixing ammonium metavanadate, ammonia water and water to obtain a mixed solution; (2) mixing the mixed solution with an oxidized graphene solution and then performing hydrothermal reaction to obtain a precursor; (3) performing freeze-drying on the precursor; and (4) performing calcination on the freeze-dried precursor in an ammonia atmosphere, and then cooling the calcined product to room temperature in the ammonia atmosphere to obtain the graphene-supported vanadium monatomic sulfur-fixing catalyst. The graphene-supported vanadium monatomic catalyst can catalyze the conversion kinetics of a sulfur positive electrode of a magnesium-sulfur battery, and effectively reduces the polarization voltage of the battery. Meanwhile, the specific capacity of a composite sulfur positive electrode composed of the graphene-supported vanadium monatomic sulfur-fixing catalyst and elemental sulfur is much higher than that of a conventional composite sulfur positive electrode composed of graphene and elemental sulfur.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and particularly relates to a graphene-supported vanadium monatomic sulfur-fixing catalyst and application thereof. BACKGROUND

[0002] With the increasing demand for energy and the increasing awareness of environmental protection, developing new battery systems with high performance, low cost and environmental friendliness has become a hot research topic. As a battery system with extremely high theoretical energy density (3221 Wh L -1 and 1684 Wh kg -1 ), low cost and high sustainability, magnesium-sulfur (Mg-S) batteries have received extensive attention in recent years.

[0003] However, magnesium-sulfur batteries still face many challenges in practical applications. For example, in magnesium-sulfur batteries, the sulfur positive electrode as the main active material undergoes complex chemical changes during the charging and discharging process. In the discharging process, sulfur (S) is reduced to magnesium sulfide (MgS), while in the charging process, magnesium sulfide is oxidized back to sulfur. However, due to the low electronic conductivity of sulfur and its reduced product magnesium sulfide, the redox reaction kinetics of the sulfur positive electrode is slow, which affects the cycle performance and energy density of the magnesium-sulfur battery.

[0004] In the prior art, in order to improve the reduction reaction kinetics of the sulfur positive electrode, researchers have tried various methods, such as introducing catalysts, optimizing electrolytes or designing new positive electrode structures. Among them, introducing catalysts has become the preferred method for most researchers due to its direct use in the reaction process and high flexibility. SUMMARY

[0005] The application develops a graphene-supported vanadium monatomic sulfur-fixing catalyst, which has a catalytic effect of improving the reaction kinetics of the reaction process and reducing the polarization voltage of the magnesium-sulfur battery. The raw materials are easy to obtain, and the preparation method is simple.

[0006] In order to achieve the above purpose, the application can adopt the following technical scheme:

[0007] The application provides a graphene-supported vanadium monatomic sulfur-fixing catalyst, and a preparation method thereof. The preparation method comprises the following steps: (1) mixing ammonium metavanadate, ammonia water and water to obtain a mixed solution; (2) mixing the mixed solution with an oxidized graphene solution and then performing a hydrothermal reaction to obtain a precursor; (3) performing freeze-drying on the precursor; and (4) performing calcination on the freeze-dried precursor in an ammonia atmosphere, and then cooling the calcined product to room temperature in the ammonia atmosphere to obtain the graphene-supported vanadium monatomic sulfur-fixing catalyst.

[0008] It should be noted that the graphene supported vanadium single atom sulfur fixation catalyst in the application is combined with elemental sulfur to form a composite sulfur positive electrode, which is applied in a battery. Compared with the existing conventional graphene and elemental sulfur composite sulfur positive electrode applied in the battery, the specific capacity of the composite sulfur positive electrode in the application is much higher than that of the conventional graphene composite sulfur positive electrode, and the polarization voltage is much lower than that of the conventional graphene composite sulfur positive electrode.

[0009] It should also be noted that the realization of graphene supported vanadium can also be in the form of vanadium doping, but the uniformity, stability, catalytic activity, selectivity and charge transport performance of vanadium doping are not as good as those of vanadium single atom. Specifically, doping generally refers to the introduction of another element or compound into graphene or other materials, which may exist in the form of clusters, nanoparticles or atoms. In graphene supported vanadium doping, vanadium may be dispersed on the surface or lattice of graphene in the form of atoms, clusters or nanoparticles; while single atom refers to an element existing in the form of a single atom in graphene or other materials, in graphene supported vanadium single atom, vanadium is uniformly dispersed in the lattice of graphene in the form of a single atom. Based on the above differences between single atom and doping, single atom has the following advantages over doping:

[0010] (1) Single atom catalyst exists in the form of a single atom in the lattice of graphene or other materials, which makes the distribution of vanadium atoms on the surface or lattice of graphene more uniform, avoiding the problem of uneven distribution of clusters or particles that may occur during doping. In addition, due to the high uniformity of single atom catalyst, it exhibits higher stability in catalytic reactions; this means that the catalyst is less likely to agglomerate or deactivate during long-term use, thereby prolonging the service life of the catalyst.

[0011] (2) Single atom catalysts often have high catalytic activity and selectivity due to their unique electronic structure and catalytic mechanism; in catalytic reactions, single atom catalysts can effectively promote the reaction, improve the reaction rate and conversion efficiency; compared with doping, single atom catalysts exhibit higher selectivity in the catalytic process, which can precisely regulate the reaction path and product structure, thereby realizing efficient and green catalytic process.

[0012] (3) When vanadium is dispersed in the form of a single atom in the lattice of graphene, the two-dimensional structure and high conductivity of graphene can be utilized to form a good electron transport channel between vanadium atoms and graphene; this electron transport channel helps to realize the rapid transfer and transfer of electrons in the catalytic reaction, which can improve the efficiency and performance of the catalytic reaction compared with doping.

[0013] Preferably, the mass ratio of ammonium metavanadate and graphene oxide can be (1:50)-(1:10), such as 1:45, 1:40, 1:35, 1:30, 1:25, 1:20, 1:15 or 1:10, etc., and more preferably 1:10.

[0014] It should be noted that the mass ratio of ammonium metavanadate and graphene oxide will affect the electrochemical performance of the prepared graphene supported vanadium monatomic sulfur fixed catalyst after being prepared into a positive electrode; specifically, when the mass ratio of ammonium metavanadate and nitrogen-doped graphene is less than 1:50, the vanadium monatomic loading will be low, the proportion of active sites of the entire material will be reduced, and the catalytic performance will be reduced; when the mass ratio of ammonium metavanadate and nitrogen-doped graphene is higher than 1:10, clusters or nanoparticles of vanadium compounds will be generated on the surface of graphene, so the mass ratio of ammonium metavanadate and graphene in the present application is preferably (1:50)-(1:10); more preferably 1:10, when the mass ratio of ammonium metavanadate and nitrogen-doped graphene is 1:10, the specific capacity of the graphene supported vanadium monatomic sulfur fixed catalyst prepared in the positive electrode material is higher than that of other mass ratios, and the positive electrode polarization voltage is lower than that of other mass ratios.

[0015] Preferably, in the above step (1), the molar ratio of ammonium metavanadate and ammonia water is (3:1)-(8:1), such as 4:1, 5:1, 6:1 or 7:1, etc.

[0016] It should be noted that when the molar ratio of ammonium metavanadate and ammonia water is less than 3, the concentration of ammonia water will be too high, the gas pressure during the reaction process will be high, and safety will be affected; when the molar ratio of ammonium metavanadate and ammonia water is higher than 8, too much ammonium metavanadate will not be completely dissolved and reacted with ammonia water, resulting in the formation of nano or micron particles in the material and affecting the catalytic activity. Therefore, the molar ratio of ammonium metavanadate and ammonia water in the present application is preferably (3:1)-(8:1).

[0017] Preferably, in step (2), the temperature of the hydrothermal reaction can be 160-200℃, such as 170℃, 180℃ or 190℃, and more preferably 180℃.

[0018] It should be noted that after ammonium metavanadate, ammonia water and water are mixed, the precursor is prepared by hydrothermal reaction with graphene oxide, the temperature of the hydrothermal reaction is preferably 160-200℃, and more preferably 180℃. At this temperature, more precursors can be prepared in a shorter time, especially at 180℃, more precursors can be obtained in the shortest time.

[0019] Preferably, in step (2), the temperature of the hydrothermal reaction can be 160-200℃, and the hydrothermal reaction time can be 11-13h.

[0020] It should be noted that, under the hydrothermal reaction temperature of 160-200 DEG C, the reaction is less than 11h, the reaction is incomplete, and the reaction is more than 13h, which may cause the growth of nanoscale crystals to affect the catalytic activity; therefore, the reaction time in the present application is preferably 11-13h.

[0021] Preferably, in step (4), the calcination temperature can be 450-650 DEG C, such as 500 DEG C, 550 DEG C or 600 DEG C, etc.

[0022] It should be noted that, if the calcination temperature is less than 450 DEG C, the vanadium single atom coordination will be unsaturated, which is unstable on the surface of nitrogen-doped graphene and affects the catalytic activity; if the calcination temperature is higher than 650 DEG C, the single atoms will be aggregated to form clusters or nanoparticles, which affects the catalytic activity; therefore, the calcination temperature in the present application is preferably 450-650 DEG C, and more preferably 550 DEG C, which can complete the calcination to prepare the graphene-supported vanadium single atom sulfur fixation catalyst with less energy consumption.

[0023] Preferably, in step (4), the calcination temperature can be 450-650 DEG C, and the calcination time can be 1-3h. It should be noted that, under the temperature of 450-650 DEG C, the reaction can be completed in 1-3h to obtain more graphene-supported vanadium single atom sulfur fixation catalyst.

[0024] Preferably, in step (4), the heating rate can be 5-10 DEG C / min, such as 7 DEG C / min, 8 DEG C / min or DEG C / min.

[0025] It should be noted that the heating rate in the present application refers to the temperature rising from room temperature to 450-650 DEG C; if the heating rate is less than 5 DEG C / min, the calcination time will be prolonged, which may cause the single atoms to be aggregated to form clusters or nanoparticles, affecting the catalytic activity; if the heating rate is higher than 10 DEG C / min, the temperature change will be large, which may also cause the single atoms to be aggregated to form clusters or nanoparticles, affecting the catalytic activity; therefore, the heating rate in the present application can be preferably 5-10 DEG C / min, which can calcine the precursor to obtain the graphene-supported vanadium single atom sulfur fixation catalyst in the present application in a short time, and the graphene-supported vanadium single atom sulfur fixation catalyst can better catalyze the conversion kinetics of the magnesium-sulfur battery sulfur positive electrode and more effectively reduce the battery polarization voltage.

[0026] Another aspect of the present application provides a use of the above-mentioned graphene-supported vanadium single atom sulfur fixation catalyst in the preparation of a magnesium-sulfur battery.

[0027] It needs to be explained that the graphene supported vanadium monatomic sulfur immobilization catalyst is applied in the sulfur magnesium battery, the sulfur positive electrode can be oxidized and reduced on the graphene carrier to be converted into short chain magnesium polysulfide, the reduction of the sulfur positive electrode is realized and magnesium storage is carried out; and after the vanadium monatomic is introduced on the graphene surface, the polarization voltage between the oxidation and reduction peaks is smaller, and the peak current density is higher, which indicates that the vanadium monatomic has the catalysis effect of improving the reaction kinetics and reducing the polarization voltage of the battery; therefore, the graphene supported vanadium monatomic sulfur immobilization catalyst is applied in the metal magnesium sulfur battery, and the electrochemical performance of the metal magnesium sulfur battery can be improved.

[0028] The present application has at least the following advantages:

[0029] (1) The specific capacity of the composite sulfur positive electrode composed of the graphene supported vanadium monatomic sulfur immobilization catalyst and sulfur element is much higher than that of the existing conventional composite sulfur positive electrode composed of graphene and sulfur element, and the specific capacity of the composite sulfur positive electrode of the present application can reach 1084mAh g -1 , which is about 150% higher than that of the existing composite sulfur positive electrode; at the same time, the polarization voltage of the composite sulfur positive electrode of the present application is much lower than that of the conventional composite sulfur positive electrode composed of graphene and sulfur element, and the polarization voltage of the composite sulfur positive electrode of the present application can be as low as 0.52V, which is about 23.5% lower.

[0030] (2) The material of the graphene supported vanadium monatomic sulfur immobilization catalyst in the present application is low in price and simple in preparation process, which is beneficial to realize scale production. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 XRD pattern of the graphene supported vanadium monatomic sulfur immobilization catalyst;

[0032] Figure 2 SEM diagram of the graphene supported vanadium monatomic sulfur immobilization catalyst;

[0033] Figure 3 High-resolution TEM diagram of the graphene supported vanadium monatomic sulfur immobilization catalyst;

[0034] Figure 4 Element distribution diagram of the graphene supported vanadium monatomic sulfur immobilization catalyst;

[0035] Figure 5 Symmetric cell cyclic voltammogram of graphene supported vanadium monatomic / MgS6 and graphene composite / MgS6 electrode;

[0036] Figure 6 Charging and discharging curve of magnesium sulfur battery assembled by graphene supported vanadium monatomic composite sulfur positive electrode;

[0037] Figure 7 Charging and discharging curve of magnesium sulfur battery assembled by graphene composite sulfur positive electrode. DETAILED DESCRIPTION

[0038] The examples are provided to better illustrate the present application, but are not intended to limit the present application to their details. Thus, many modifications and variations of the application are possible without departing from the scope and spirit of the application.

[0039] The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the disclosure. As used in the description herein, the expression including singular forms of "a," "an," and "the" are intended to include plural forms of the expression, unless the context clearly indicates otherwise. As used herein, it is also to be understood that the terms such as "including," "having," "with," "contain," "comprising," "comprise," "comprised of," "comprising of," "comprise of," and the like are to be construed as specifying existence of the stated features, numbers, operations, components, parts, elements, materials, or combinations thereof, in the description of the specification. The terms of the present application are disclosed in the specification, and are not intended to exclude the possibility that one or more other features, numbers, operations, components, parts, elements, materials, or combinations thereof can exist or can be added. As used herein, " / " can be interpreted as "and" or "or" depending on the situation.

[0040] In order to better understand the present application, the content of the present application is further illustrated below in combination with specific examples, but the content of the present application is not limited only to the following examples.

[0041] I. Preparation of graphene-supported vanadium monatomic sulfur- immobilized catalyst

[0042] Example 1

[0043] (1) 10 mg of ammonium metavanadate, 1 mL of ammonia water (28%), and 4 mL of deionized water were mixed and stirred until completely dissolved to form a colorless solution;

[0044] (2) 10 mL of 10 mg / mL graphene oxide solution was further added to the above solution, and after stirring uniformly, the solution was placed in a sealed reaction kettle, and hydrothermal treatment was carried out at 180°C for 12 h to obtain a precursor material, which was washed with deionized water at room temperature for 3 times and then freeze-dried;

[0045] (3) The dried material was placed in a tube furnace and calcined at 550°C for 3 h under flowing ammonia gas atmosphere, with a heating rate of 10°C / min. After calcination, it was cooled to room temperature under ammonia gas atmosphere to obtain a graphene-supported vanadium monatomic sulfur-immobilized catalyst.

[0046] Example 2

[0047] (1) 10 mg of ammonium metavanadate, 1 mL of ammonia water (28%), and 4 mL of deionized water were mixed and stirred until completely dissolved to form a colorless solution;

[0048] (2) Further 20 mL of 10 mg / mL graphene oxide solution was added to the above solution, after stirring evenly, the solution was put into a sealed reactor, hydrothermal at 180℃ for 12 h, the precursor material was obtained, washed with deionized water at room temperature for 3 times and then freeze-dried;

[0049] (3) The dried material was placed in a tube furnace, calcined at 550℃ for 3 h under flowing ammonia atmosphere, the heating rate was 10℃ / min, after calcination, it was cooled to room temperature under ammonia atmosphere, to obtain graphene supported vanadium monatomic sulfur-impregnated catalyst.

[0050] Example 3

[0051] (1) 10 mg of ammonium metavanadate, 1 mL of ammonia water (28%) and 4 mL of deionized water were mixed and stirred until completely dissolved to form a colorless solution;

[0052] (2) Further 20 mL of 10 mg / mL graphene oxide solution was added to the above solution, after stirring evenly, the solution was put into a sealed reactor, hydrothermal at 180℃ for 12 h, the precursor material was obtained, washed with deionized water at room temperature for 3 times and then freeze-dried;

[0053] (3) The dried material was placed in a tube furnace, calcined at 550℃ for 3 h under flowing ammonia atmosphere, the heating rate was 10℃ / min, after calcination, it was cooled to room temperature under ammonia atmosphere, to obtain graphene supported vanadium monatomic sulfur-impregnated catalyst.

[0054] Comparative Example 1

[0055] A conventional graphene material was used as a comparative example.

[0056] II. Characterization of graphene supported vanadium monatomic sulfur-impregnated catalyst

[0057] (1) XRD pattern analysis

[0058] The graphene supported vanadium monatomic sulfur-impregnated catalyst prepared in the above Example 1 was subjected to XRD pattern analysis, and the results are shown in Figure 1 The results show that there is no crystal peak in the XRD pattern, indicating that vanadium is mainly loaded on the surface of graphene in the form of single atom.

[0059] (2) SEM pattern analysis

[0060] The graphene supported vanadium monatomic sulfur-impregnated catalyst prepared in the above Example 1 was subjected to SEM pattern analysis, and the results are shown in Figure 2 The results show that there is no vanadium oxide or vanadium nitride impurities in the prepared material.

[0061] (3) Aberration-corrected electron microscopy analysis

[0062] The graphene-supported vanadium monatomic sulfur-fixing catalyst prepared in the above Example 1 was subjected to spherical aberration electron microscopy analysis, and the results are shown in Figure 3 The results show that, under high resolution, vanadium atoms can be observed to be uniformly supported on the surface of the graphene substrate without forming obvious ordered arrangement.

[0063] (4) EDS element analysis

[0064] The graphene-supported vanadium monatomic sulfur-fixing catalyst prepared in the above Example 1 was subjected to EDS element analysis, and the results are shown in Figure 4 The results show that the catalyst is mainly composed of C, V and N elements, wherein C is derived from graphene, the signal of V is derived from vanadium monatomic; the presence of N indicates that vanadium monatomic is mainly anchored on the surface of graphene through V-N bond.

[0065] III. Mass loading of vanadium monatomic in graphene-supported vanadium monatomic sulfur-fixing catalyst

[0066] The mass loading of vanadium in the graphene-supported vanadium monatomic sulfur-fixing catalyst prepared in Examples 1 to 3 was tested (the mass loading of vanadium was quantitatively tested by inductively coupled plasma spectroscopy (ICP) (Thermo Fisher Corporation, iCAP6300 Duo)), and the results are shown in Table 1 below.

[0067] Table 1 Mass loading of vanadium monatomic in different examples

[0068]

[0069] IV. Electrochemical test of graphene-supported vanadium monatomic sulfur-fixing catalyst and MgS6 assembled symmetrical battery

[0070] In the embodiments of the present application, the preparation method of the MgS6 liquid positive electrode comprises: mixing anhydrous MgS and S powder in a molar ratio of 1:5 in a DMSO solvent, wherein the concentration of MgS is 0.5 mol / L, mixing under an argon atmosphere, stirring at 80°C until the powder is completely dissolved, and the solution turns into a dark red solution, thereby obtaining the MgS6 liquid positive electrode.

[0071] The graphene-supported vanadium monatomic sulfur-fixing catalyst prepared in the above Example 1 and the conventional graphene material (Comparative Example 1) were respectively compounded with the MgS6 liquid positive electrode prepared above, specifically comprising: dissolving the MgS6 liquid positive electrode in a dimethyl sulfoxide (DMSO) solvent with a concentration of 0.5 mol / L, then adding it dropwise into the graphene-supported vanadium monatomic sulfur-fixing catalyst and the conventional graphene material (wherein, sulfur 70wt%, support material (graphene-supported vanadium monatomic sulfur-fixing catalyst or conventional graphene material) 30wt%), then assembling a symmetrical battery, and testing the battery in a voltage range of -1V-1V and a scan rate of 5mVs -1Cyclic voltammetry tests were conducted at a sweep rate of [missing value].

[0072] The results are as follows Figure 5 As shown, the results indicate that the graphene / MgS6 symmetric battery exhibits significant redox peaks at 0.42V and -0.34V, with a polarization voltage of 0.76V. This suggests that MgS6 undergoes a redox reaction on the graphene support, transforming into short-chain magnesium polysulfides, which is the reaction mechanism for sulfur reduction and magnesium storage at the cathode. In contrast, after introducing vanadium single atoms onto the graphene surface, the polarization voltage between the redox peaks (0.4V) is smaller, and the peak current density is higher, indicating that vanadium single atoms have a catalytic effect of improving reaction kinetics and reducing battery polarization voltage.

[0073] V. Performance Tests of Graphene-Supported Vanadium Single-Atom Sulfur Fixation Catalyst

[0074] The graphene-supported vanadium single-atom sulfur fixation catalysts prepared in Examples 1 to 3 above and conventional graphene materials (Comparative Example 1) were respectively composited with elemental sulfur (wherein, sulfur is 70 wt% and the support material (graphene-supported vanadium single-atom sulfur fixation catalyst or conventional graphene material) is 30 wt%) to form composite sulfur cathodes. These were then matched with 0.5 mol / L magnesium trifluoromethanesulfonate / MgCl2 / AlCl3 electrolyte and a metallic magnesium anode to assemble magnesium-sulfur batteries. The batteries were tested at 100 mA g. -1 Constant current charge-discharge tests were performed at a current density, and the results are shown in Table 2 below.

[0075] Table 2. Specific capacity and polarization voltage of composite sulfur cathodes in Examples 1 to 3 and Comparative Example 1.

[0076]

[0077] As shown in Table 2 above, compared with the composite sulfur cathode composed of graphene-supported vanadium single-atom sulfur fixation catalyst and elemental sulfur prepared in Examples 1 to 3, the specific capacity of the composite sulfur cathode composed of graphene (Comparative Example 1) and elemental sulfur is much higher than that of Comparative Example 1, and the polarization voltage is much lower than that of Comparative Example 1.

[0078] Additionally, at a ratio of 1:10, the specific capacity is 1084 mAh g. -1 Meanwhile, the polarization voltage is as low as 0.52V; therefore, the preferred mass ratio of ammonium metavanadate to graphene oxide in this invention is 1:10. Furthermore, when the mass ratio of ammonium metavanadate to graphene oxide is greater than 1:10, agglomerated nanoparticles will appear, affecting the catalytic activity, and its catalytic activity is not as good as that of 1:10.

[0079] In addition, the charge-discharge test results of the graphene-supported vanadium monatomic sulfur immobilization catalyst and elemental sulfur composite composite sulfur positive electrode in Example 1 (mass ratio of ammonium metavanadate to graphene oxide is 1:10) are shown in Figure 6 and Figure 7 The results show that the graphene-supported vanadium monatomic composite sulfur positive electrode can release a high specific capacity of 1084 mAh g -1 in the first cycle, which is significantly higher than that of the conventional graphene composite sulfur positive electrode (433 mAh g -1 ), which is about 150% higher; after 15 cycles, the specific capacity can still be maintained at 905 mAh g -1 ; in addition, the charge-discharge polarization voltage of the graphene-supported vanadium monatomic composite sulfur positive electrode (0.52 V) is also significantly lower than that of the conventional graphene composite sulfur positive electrode (0.68 V), which is about 23.5% lower.

[0080] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and they should be covered by the scope of the claims of the present application.

Claims

1. A graphene supported vanadium monatomic sulfur fixation catalyst, characterized in that, The preparation method comprises the following steps: (1) mixing ammonium metavanadate, ammonia water and water to obtain a mixed solution; (2) mixing the mixed solution with a graphene oxide solution and then performing a hydrothermal reaction to obtain a precursor; (3) performing freeze drying on the precursor; and (4) performing calcination on the freeze-dried precursor in an ammonia atmosphere, and then cooling the calcined product to room temperature in the ammonia atmosphere to obtain the graphene-supported vanadium monatomic sulfur-fixed catalyst.

2. The graphene supported vanadium monatomic sulfur fixation catalyst according to claim 1, wherein, The mass ratio of the ammonium metavanadate to the graphene oxide is (1:50)-(1:10).

3. The graphene supported vanadium monatomic sulfur fixation catalyst according to claim 2, wherein, The mass ratio of the ammonium metavanadate to the graphene oxide is 1:

10.

4. The graphene supported vanadium monatomic sulfur capture catalyst according to any one of claims 1 to 3, wherein, In step (1), the molar ratio of the ammonium metavanadate to the ammonia water is (3:1)-(8:1).

5. The graphene supported vanadium monatomic sulfur capture catalyst according to any one of claims 1 to 3, wherein, In step (2), the temperature of the hydrothermal reaction is 160-200 DEG C.

6. The graphene-supported vanadium monatomic sulfur fixation catalyst according to claim 5, wherein, In step (2), the hydrothermal reaction time is 11-13 hours.

7. The graphene supported vanadium monatomic sulfur capture catalyst according to any one of claims 1 to 3, wherein, In step (4), the calcination temperature is 450-650 DEG C.

8. The graphene-supported vanadium monatomic sulfur fixation catalyst according to claim 7, wherein, In step (4), the calcination time is 1-3 hours.

9. The graphene-supported vanadium monatomic sulfur-fixing catalyst of claim 1, 2, 3, 6, or 8, wherein, In step (4), the temperature rising rate is 5-10 DEG C / min.

10. The graphene-supported vanadium monatomic sulfur-fixed catalyst according to any one of claims 1-9 is used in the preparation of a magnesium metal-sulfur battery.

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