Layered vanadium pentoxide composite material, preparation method thereof and magnesium secondary battery

Abstract

The invention provides a layered vanadium pentoxide composite material, a preparation method thereof and a magnesium secondary battery, and the method comprises the following steps: (1) mixing V2O5 with water to obtain a solution A; (2) mixing the solution A with a hydrogen peroxide solution to obtain a solution B; (3) mixing the solution B with a pyrrole monomer to obtain a solution C; and (4) carrying out hydrothermal reaction on the solution C to obtain the layered vanadium pentoxide composite material. The layered vanadium pentoxide composite material obtained by the method disclosed by the invention has excellent ionic conductivity, electronic conductivity and cycling stability, so that when the layered vanadium pentoxide composite material is applied to a battery, the rate, the capacity and the cycle life of the battery can be improved.

Description

Technical Field

[0001] This application belongs to the field of batteries, and particularly relates to a layered vanadium pentoxide composite material, its preparation method, and a magnesium secondary battery. Background Technology

[0002] Magnesium metal batteries are made from magnesium, which has a high theoretical volumetric capacity (3833 mAh cm⁻¹). -3 Magnesium ions (Mg) have attracted widespread attention due to their low redox potential (-2.73 V vs. standard hydrogen electrode, SHE), high natural abundance (ranking 8th in the Earth's crust and 3rd in seawater), and relatively low chemical reactivity. Furthermore, their typical hexagonal close-packed (hcp) crystal structure makes them less prone to sharp dendrite formation during charge-discharge cycles, thus providing higher safety. Meanwhile, the divalent nature of magnesium ions gives them a higher theoretical volumetric capacity compared to monovalent lithium ions, making rechargeable magnesium-ion batteries possible for applications in electric vehicles and even smart grids. However, the high charge density of Mg... 2+ The migration rate within the cathode lattice is extremely slow, and there is a stronger Coulomb interaction with the cathode material; this results in the small ionic radius of Mg 2+ (0.72 Å / 0.76 Å, Mg) 2+ / Li + It can only exhibit slow electrode reaction kinetics and structural stability, which is one of the core bottlenecks in the current development of magnesium-ion batteries.

[0003] Vanadium pentoxide (V₂O₅) forms a layered structure composed of alternating VO₅ pyramid layers with shared edges and corners, creating two-dimensional diffusion channels that facilitate magnesium ion migration; its diverse stable oxidation states also contribute to the diffusion of magnesium ions in Mg. 2+ Maintaining local charge neutrality during the insertion / extraction process, thereby enhancing Mg 2+ The reversible insertion / extraction efficiency is high. However, V₂O₅ has low intrinsic conductivity, and divalent Mg... 2+ With high charge density, the strong interaction between the two can easily lead to significant polarization and structural stress in the positive electrode lattice, resulting in rapid capacity decay and limiting its further application in magnesium secondary batteries. Summary of the Invention

[0004] This application provides a layered vanadium pentoxide composite material, its preparation method, and a magnesium secondary battery. The layered vanadium pentoxide composite material obtained by the method of this application has excellent ionic conductivity, electronic conductivity, and cycle stability. Therefore, its use in magnesium secondary batteries can improve the battery's rate capability, capacity, and cycle life.

[0005] In one aspect of this application, a method for preparing layered vanadium pentoxide composite materials is provided, comprising: (1) Mix V2O5 with water to obtain solution A; (2) Mix the solution A with hydrogen peroxide solution to obtain solution B; (3) Mix the solution B with the pyrrole monomer to obtain solution C; (4) The solution C is subjected to a hydrothermal reaction to obtain a layered vanadium pentoxide composite material.

[0006] In some embodiments, the solid-liquid ratio of the V2O5 to the hydrogen peroxide solution is (18mg-37mg):(2mL-5mL).

[0007] In some embodiments, the mass concentration of the hydrogen peroxide solution is 20-40%.

[0008] In some embodiments, the solid-liquid ratio of the V2O5 to the pyrrole monomer is (18mg-37mg):(50μL-400μL).

[0009] In some embodiments, in step (4), the temperature of the hydrothermal reaction is 150-200°C and the time is 8-16 hours.

[0010] In some embodiments, in step (4), the solution C is transferred to a stainless steel reactor with a polytetrafluoroethylene liner for hydrothermal reaction, and the solid precipitate after reaction is filtered, washed and dried to obtain the layered vanadium pentoxide composite material.

[0011] In some embodiments, the drying temperature is 60-100°C and the time is 8-12 hours.

[0012] In a second aspect of this application, a layered vanadium pentoxide composite material is proposed, which is prepared using the method described in the first aspect of this application.

[0013] In a third aspect of this application, a positive electrode sheet is proposed, comprising a layered vanadium pentoxide composite material prepared by the method described in the first aspect of this application or the layered vanadium pentoxide composite material described in the second aspect of this application.

[0014] In a fourth aspect of this application, a magnesium secondary battery is proposed, comprising the positive electrode sheet described in the third aspect of this application.

[0015] In some embodiments, the magnesium secondary battery includes a magnesium-ion battery or a magnesium metal battery.

[0016] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a process flow diagram of the preparation of layered vanadium pentoxide composite material according to one embodiment of this application; Figure 2 The XRD pattern of the layered vanadium pentoxide composite material prepared in Example 2 of this application; Figure 3 The rate performance of the layered vanadium pentoxide composite material prepared in Example 1 of this application after being assembled into a magnesium-ion battery at different current densities is shown in the graph. Figure 4 The rate performance of the layered vanadium pentoxide composite material prepared in Example 2 of this application after being assembled into a magnesium-ion battery at different current densities is shown in the graph. Figure 5 The rate performance of the layered vanadium pentoxide composite material prepared in Example 3 of this application after being assembled into a magnesium-ion battery at different current densities is shown in the graph. Figure 6 GCD diagrams of the layered vanadium pentoxide composite material prepared in Example 1 of this application assembled into a magnesium-ion battery at different current densities; Figure 7 GCD diagrams of the layered vanadium pentoxide composite material prepared in Example 2 of this application assembled into a magnesium-ion battery at different current densities; Figure 8 GCD diagrams of the layered vanadium pentoxide composite material prepared in Example 3 of this application assembled into a magnesium-ion battery at different current densities; Figure 9 After the layered vanadium pentoxide composite material prepared in Example 2 of this application was assembled into a magnesium-ion battery, it was tested at 50 mA g. -1 Cyclic curves at current density; Figure 10 After the layered vanadium pentoxide composite material prepared in Example 2 of this application was assembled into a magnesium metal battery, it was tested at 20 mA g. -1 GCD plot at current density. Detailed Implementation

[0018] The following detailed description, with appropriate reference to the accompanying drawings, discloses a specific embodiment of a battery pack according to this application. However, some unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of essentially the same structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0019] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is also expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers, and ranges defined in this way can include endpoints a and b. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0020] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0021] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0022] The first aspect of this application discloses a method for preparing layered vanadium pentoxide composite materials, referring to... Figure 1 The method includes: (1) Mix V2O5 with water to obtain solution A; (2) Mix the solution A with hydrogen peroxide solution to obtain solution B; (3) Mix the solution B with the pyrrole monomer to obtain solution C; (4) The solution C is subjected to a hydrothermal reaction to obtain a layered vanadium pentoxide composite material.

[0023] This application employs a simple hydrothermal method to introduce polypyrrole material in situ between the layers of layered V2O5 material. The highly conductive polypyrrole enhances the ionic / electronic conductivity and structural stability of the V2O5 material, thereby improving the rate, capacity and cycle life of the battery when used in magnesium secondary batteries. At the same time, the composite material is compatible with the rapid and reversible deposition kinetics on the surface of magnesium metal anode, resulting in good electrochemical performance of the assembled magnesium secondary battery.

[0024] In some embodiments, the solid-liquid ratio of V₂O₅ to the hydrogen peroxide solution is (18mg-37mg):(2mL-5mL), for example, 18mg:(2mL-5mL), 20mg:(2mL-5mL), 25mg:(2mL-5mL), 30mg:(2mL-5mL), 35mg:(2mL-5mL), 37mg:(2mL-5mL), (18mg-37mg):2mL, (18mg-37mg):3mL, (18mg-37mg):4mL, (18mg-37mg):5mL, etc. Therefore, mixing V₂O₅ and the hydrogen peroxide solution in this ratio not only ensures the formation of a layered composite phase but also improves the crystallinity of the product. Further, the mass concentration of the hydrogen peroxide solution is 20-40%.

[0025] In some embodiments, the solid-liquid ratio of V2O5 to the pyrrole monomer is (18mg-37mg):(50μL-400μL), for example 18mg:(50μL-400μL), 20mg:(50μL-400μL), 25mg:(50μL-400μL), 30mg:(50μL-400μL), 35mg:(50μL-400μL), 37mg:(50μL-400μL), (18mg-37mg):50μL, (18mg-37mg):100μL, (18mg-37mg):200μL, (18mg-37mg):300μL, (18mg-37mg):400μL, etc. Therefore, mixing V2O5 and the pyrrole monomer in the above ratio can ensure that sufficient polypyrrole enters the interlayer of V2O5, thereby improving the ionic conductivity and electronic conductivity of the composite material.

[0026] In some embodiments, in step (4), the hydrothermal reaction is carried out at a temperature of 150-200°C for 8-16 hours, for example, at temperatures of 150°C, 170°C, 190°C, or 200°C, for times of 8 hours, 10 hours, 12 hours, 14 hours, or 16 hours. Under these conditions, the hydrothermal reaction allows polypyrrole (PPy) to polymerize in situ within the interlayer of the V2O5 material, i.e., polypyrrole enters the interlayer of V2O5, thereby improving the ionic and electronic conductivity of the composite material.

[0027] In some embodiments, in step (4), the solution C is transferred to a stainless steel reactor with a polytetrafluoroethylene liner for hydrothermal reaction, and the solid precipitate after reaction is filtered, washed and dried to obtain the layered vanadium pentoxide composite material, wherein the drying temperature is 60-100℃ and the time is 8-12h.

[0028] Compared with the prior art, this application has the following beneficial effects: 1. This application employs a simple hydrothermal method to achieve in-situ polymerization of pyrrole between V₂O₅ material layers. This not only improves the intrinsic electronic conductivity of the material and widens the interlayer spacing of V₂O₅, significantly enhancing its electronic and ionic conductivity, but also significantly strengthens ion migration ability by expanding the interlayer spacing of V₂O₅, thereby synergistically improving the material's electronic and ionic conductivity and effectively increasing its actual specific capacity and cycle stability. Simultaneously, thanks to the optimized layered structure and conductive network, this composite cathode exhibits rapid and reversible Mg polymerization. 2+ The insertion / extraction kinetics are well compatible with the deposition / dissolution kinetics on the surface of magnesium metal anodes, expanding the application prospects of vanadium pentoxide-based cathodes in magnesium metal batteries.

[0029] 2. The layered vanadium pentoxide composite material prepared in this application possesses both high ionic / electronic conductivity and excellent structural stability. Magnesium-ion batteries assembled using this material as a cathode exhibit excellent electrochemical performance. Furthermore, the conductive polypyrrole (PPy) network promotes charge transport, and the composite material interacts well with the magnesium metal anode in the Mg... 2+ The good compatibility between the insertion / extraction and Mg deposition / dissolution kinetics allows the magnesium metal full cell with this composite material as the positive electrode and magnesium metal as the negative electrode to still maintain a high reversible capacity.

[0030] 3. When the layered vanadium pentoxide composite material prepared in this application is used as a positive electrode material for magnesium-ion batteries, at 20 mA g... -1 It exhibits a high current density of 186.7 mAh g. -1 It has high specific capacitance and excellent rate performance: when the current density is increased to 2000 mA g -1 At that time, the specific capacity remained at 93.3 mAh g. -1;at 500 mA g -1 After 1000 cycles at current density, the capacity retention rate is as high as 83%, indicating that the material has both high capacity and long cycle stability, and is expected to become an ideal cathode candidate material for high-performance magnesium-ion batteries and magnesium metal batteries.

[0031] In a second aspect, this application proposes a layered vanadium pentoxide composite material, which is prepared using the method described in the first aspect of this application. Therefore, this layered vanadium pentoxide composite material exhibits excellent ionic conductivity, electronic conductivity, and cycle stability, thus its use in batteries can improve battery capacity and cycle life.

[0032] It should be noted that the features and advantages described above for the preparation of layered vanadium pentoxide composite materials also apply to this layered vanadium pentoxide composite material, and will not be repeated here.

[0033] In a third aspect, this application proposes a positive electrode sheet comprising a layered vanadium pentoxide composite material prepared using the method described in the first aspect of this application or the layered vanadium pentoxide composite material described in the second aspect of this application. Thus, by using the aforementioned layered vanadium pentoxide composite material with excellent ionic conductivity, electronic conductivity, and cycle stability as the positive electrode active material, this positive electrode sheet can improve the battery's capacity and cycle life when used in a battery.

[0034] It should be noted that the features and advantages described above for the layered vanadium pentoxide composite material and its preparation method also apply to this positive electrode sheet, and will not be repeated here.

[0035] In a fourth aspect, this application discloses a magnesium secondary battery, including the positive electrode sheet described in the third aspect. In some embodiments of this application, the magnesium secondary battery includes a magnesium-ion battery or a magnesium metal battery. Therefore, this magnesium secondary battery has high capacity and cycle life. It should be noted that the features and advantages described above for the positive electrode also apply to this magnesium secondary battery, and will not be repeated here.

[0036] The embodiments of this application are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. In addition, unless otherwise specified, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods described herein or known methods. For reaction conditions not listed, they are also readily available to those skilled in the art.

[0037] Example 1 This embodiment provides a method for preparing layered vanadium pentoxide composite material, including the following steps: 1 mmol of V₂O₅ was dissolved in 25 mL of deionized water. 5 mL of a 30% (w / w) hydrogen peroxide solution was slowly added under stirring until the V₂O₅ was completely dissolved, forming a homogeneous, orange-red, transparent solution. Then, 100 μL of pyrrole monomer was added, and stirring continued until fully mixed. The resulting solution was transferred to a polytetrafluoroethylene-lined stainless steel reactor and hydrothermally reacted at 170°C for 10 h. After the reaction, the mixture was allowed to cool naturally to room temperature. The product was filtered through deionized water, washed three times, and then dried under vacuum at 60 °C for 12 h to obtain a layered vanadium pentoxide composite material (denoted as VOP-1).

[0038] Example 2 This embodiment provides a method for preparing layered vanadium pentoxide composite material, including the following steps: 1 mmol of V₂O₅ was dissolved in 25 mL of deionized water. 5 mL of a 30% (w / w) hydrogen peroxide solution was slowly added under stirring until the V₂O₅ was completely dissolved, forming a homogeneous, orange-red, transparent solution. Then, 200 μL of pyrrole monomer was added, and stirring continued until fully mixed. The resulting solution was transferred to a polytetrafluoroethylene-lined stainless steel reactor and hydrothermally reacted at 170°C for 10 h. After the reaction, the mixture was allowed to cool naturally to room temperature. The product was filtered through deionized water, washed three times, and then dried under vacuum at 60 °C for 12 h to obtain a layered vanadium pentoxide composite material (denoted as VOP-2).

[0039] Example 3 This embodiment provides a method for preparing layered vanadium pentoxide composite material, including the following steps: 1 mmol of V₂O₅ was dissolved in 25 mL of deionized water. 5 mL of a 30% (w / w) hydrogen peroxide solution was slowly added under stirring until the V₂O₅ was completely dissolved, forming a homogeneous, orange-red, transparent solution. Then, 300 μL of pyrrole monomer was added, and stirring continued until fully mixed. The resulting solution was transferred to a polytetrafluoroethylene-lined stainless steel reactor and hydrothermally reacted at 170°C for 10 h. After the reaction, the mixture was allowed to cool naturally to room temperature. The product was filtered through deionized water, washed three times, and then dried under vacuum at 60 °C for 12 h to obtain a layered vanadium pentoxide composite material (denoted as VOP-3).

[0040] Comparative Example This embodiment provides a method for preparing layered vanadium pentoxide composite material, including the following steps: 1 mmol V₂O₅ was dissolved in 25 mL of deionized water. 5 mL of a 30% (w / w) hydrogen peroxide solution was slowly added under stirring until the V₂O₅ was completely dissolved, forming a homogeneous, orange-red, transparent solution. Then, 200 μL of polypyrrole was added, and stirring continued until fully mixed. The resulting solution was transferred to a polytetrafluoroethylene-lined stainless steel reactor and hydrothermally reacted at 170°C for 10 h. After the reaction, the mixture was allowed to cool naturally to room temperature. The product was filtered through deionized water, washed three times, and then dried under vacuum at 60 °C for 12 h to obtain the vanadium pentoxide composite material.

[0041] (1) XRD tests were performed on the composite materials obtained in Examples 1-3 and the comparative examples. Figure 2 The image shows the X-ray diffraction (XRD) pattern of the layered vanadium pentoxide composite material prepared in Example 2. As shown in the figure, the XRD pattern of the layered vanadium pentoxide composite material prepared in Example 2 exhibits typical layered structure characteristics. The (001) crystal plane diffraction peak is significantly shifted to a lower angle compared to the standard card JCPDS#16-0601, indicating a significant increase in the VO interlayer spacing, which reaches as high as 13.7 Å. This phenomenon is attributed to the in-situ polymerized PPy and structural water molecules being embedded in the interlayer, effectively widening the VO interlayer spacing as "interlayer pillars" and enhancing interlayer interactions, thereby synergistically increasing the Mg content in the material. 2+ Ion diffusion kinetics and structural stability during cycling. The vanadium pentoxide composites prepared in Examples 1, 3-5 were tested using the same method, and the results were basically consistent with those of Example 1. However, the XRD pattern of the vanadium pentoxide composite obtained in the comparative example showed no significant shift in the (001) crystal plane diffraction peak compared to the standard card JCPDS#16-0601, indicating that the VO interlayer spacing remained unchanged at 11.6 Å.

[0042] (2) Electrochemical tests were conducted on the magnesium-ion battery. A positive electrode slurry (50 wt% solid content) was prepared by mixing positive active material with conductive carbon black and binder PVDF in a mass ratio of 7:2:1 and then adding NMP (N-methylpyrrolidone). The positive electrode slurry was coated on one side of a carbon paper current collector and rolled dry to obtain a positive electrode sheet (0.15 mm thick). A negative electrode slurry (60 wt% solid content) was prepared by mixing activated carbon with conductive carbon black and binder PVDF in a mass ratio of 8:1:1 and then adding NMP (N-methylpyrrolidone). The negative electrode slurry was loaded onto a conductive carbon cloth current collector and rolled dry to obtain a negative electrode sheet (0.2 mm thick). Using 0.5 M Mg(TFSI)2 / AN as the electrolyte, 2032 button cells were assembled and their electrochemical performance was tested.

[0043] The vanadium pentoxide composite materials obtained in Examples 1-3 and the comparative example were used as positive electrode materials to assemble 2032 button batteries according to the above method, and electrochemical tests were conducted. A Neware-CT8000 charge-discharge testing system was used to perform constant current charge-discharge (GCD) tests on the batteries.

[0044] Figure 3-5 The figures show the rate performance of VOP-1, VOP-2, and VOP-3 prepared in Examples 1, 2, and 3 of this application as positive electrode active materials for magnesium-ion batteries at different current densities. The results indicate that the batteries corresponding to the positive electrode materials prepared in Examples 1-3 exhibit excellent specific capacity and rate performance, which are higher than those corresponding to the composite materials prepared in the comparative examples. In particular, the positive electrode material of Example 2 exhibits excellent specific capacity and rate performance at 20 mA g⁻¹. -1 At current density, its specific capacity can reach 186.7 mAh g⁻¹. -1 Increase the current density to 2000 mA g -1 At that time, it still had 93.3mAh g -1 The high specific capacity. Therefore, the composite material of this application exhibits both excellent initial specific capacity and rate performance in magnesium-ion batteries.

[0045] Figure 6-8 The GCD curves of VOP-1, VOP-2, and VOP-3, prepared in Examples 1, 2, and 3 of this application, as positive electrode active materials for magnesium-ion batteries, are shown at different current densities. Figure 6-8 It can be seen that the magnesium-ion batteries assembled from the composite materials in Examples 1-3 of the present invention have a wider voltage window than the batteries corresponding to the composite materials prepared in the comparative examples, thus indicating that the composite materials of the present invention have higher electrochemical stability.

[0046] Figure 9 The 2032 coin cell assembled using VOP-2, prepared as the active material for a magnesium-ion battery in Example 2 of this application, was tested at 500 mA g. -1 The long-cycle performance diagram at current density. (From...) Figure 9 It can be seen that the VOP-2 cathode material assembled battery prepared in Example 2 also exhibits excellent cycle stability: after 1000 charge-discharge cycles, its capacity retention rate reaches 83%; the cathode material assembled battery prepared in Example 1, after 1000 charge-discharge cycles, its capacity retention rate is 51.7%; the cathode material assembled battery prepared in Example 3, after 1000 charge-discharge cycles, its capacity retention rate is 82%, and the capacity retention rates of the batteries corresponding to Examples 1-3 after 1000 cycles are all higher than those of the corresponding batteries in the comparative examples. This shows that the composite material obtained by the method of the present invention, as the cathode of a magnesium-ion battery, can improve the cycle life of the battery.

[0047] (3) Magnesium metal battery A positive electrode slurry (50 wt% solid content) was prepared by mixing positive electrode active material with conductive agent carbon black and binder PVDF at a mass ratio of 7:2:1 and then adding NMP (N-methylpyrrolidone). The positive electrode slurry was coated onto one side of a carbon paper current collector and rolled and dried to obtain a positive electrode sheet (0.15 mm thick). A 2032 button cell was assembled using polished and cleaned magnesium foil as the negative electrode sheet (0.2 mm thick) and 0.4 M commercial APC electrolyte (PhMgCl+AlCl3) for electrochemical performance testing. The composite materials prepared in Examples 1-3 were used as positive electrode active materials and assembled into magnesium metal batteries according to the above method. The GCD test of the above positive electrode materials was performed using the Neware-CT8000 charge-discharge test system.

[0048] Figure 10 When the VOP-2 prepared in Example 2 of this application is used as the positive electrode active material of a magnesium metal battery, at 20 mA g -1 The GCD curve at the current density. (From...) Figure 10 It can be seen that this magnesium metal battery provides 26.3 mA g. -1 The initial discharge specific capacity and 30.9 mA g -1 Reversible charging specific capacity. The above results indicate that the in-situ polymerization of pyrrole in vanadium pentoxide effectively and synergistically enhances the electronic / ionic conductivity of the material, significantly improves the electrode reaction kinetics, and enables rapid and reversible polymerization of pyrrole with magnesium metal on the magnesium anode surface. 2+ It exhibits good potential for practical applications due to its compatibility with deposition / dissolution kinetics.

[0049] The layered vanadium pentoxide composite material prepared in Examples 1, 3-5 was used as the positive electrode active material to assemble magnesium metal batteries according to the above method, and the above electrochemical performance tests were conducted. The batteries showed similar electrochemical performance.

[0050] Therefore, the composite material prepared using this application has excellent ionic conductivity, electronic conductivity and cycle stability, which can improve the rate, capacity and cycle life of magnesium-ion batteries and magnesium metal batteries.

[0051] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing layered vanadium pentoxide composite materials, characterized in that, include: (1) Mix V2O5 with water to obtain solution A; (2) Mix the solution A with hydrogen peroxide solution to obtain solution B; (3) Mix the solution B with the pyrrole monomer to obtain solution C; (4) The solution C is subjected to a hydrothermal reaction to obtain a layered vanadium pentoxide composite material.

2. The method according to claim 1, characterized in that, The solid-liquid ratio of V2O5 to the hydrogen peroxide solution is (18mg-37mg):(2mL-5mL); Optionally, the mass concentration of the hydrogen peroxide solution is 20-40%.

3. The method according to claim 1 or 2, characterized in that, The solid-liquid ratio of V2O5 to the pyrrole monomer is (18mg-37mg):(50μL-400μL).

4. The method according to claim 1, characterized in that, In step (4), the temperature of the hydrothermal reaction is 150-200℃ and the time is 8-16h.

5. The method according to claim 1 or 4, characterized in that, In step (4), the solution C is transferred to a stainless steel reactor with a polytetrafluoroethylene liner for hydrothermal reaction, and the solid precipitate after the reaction is filtered, washed and dried to obtain the layered vanadium pentoxide composite material.

6. The method according to claim 5, characterized in that, The drying temperature is 60-100℃, and the time is 8-12 hours.

7. A layered vanadium pentoxide composite material, characterized in that, It is prepared by any one of claims 1-6.

8. A positive electrode sheet, characterized in that, This includes layered vanadium pentoxide composite materials prepared by the method of any one of claims 1-6 or the layered vanadium pentoxide composite material of claim 7.

9. A magnesium secondary battery, characterized in that, Includes the positive electrode sheet as described in claim 8.

10. The magnesium secondary battery according to claim 9, characterized in that, The magnesium secondary battery includes a magnesium-ion battery or a magnesium metal battery.

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