Preparation method and application of organic polymer composite vanadium-based aqueous zinc battery positive electrode

Abstract

The application discloses a preparation method of an organic polymer composite vanadium-based water-based zinc battery positive electrode and application thereof. V2O5 powder is dissolved in deionized water, and continuous stirring is carried out until the V2O5 powder is completely dissolved, and the solution presents orange yellow. Then, 1,8-NDA powder is added into the solution twice, and continuous stirring is carried out until the 1,8-NDA powder is completely dissolved, and the solution presents yellow green. The solution is transferred into a hydrothermal kettle, and is placed into a vacuum drying box, and heated at 140 DEG C for 24 h. After cooling to room temperature, the solid product is centrifugally washed with deionized water and ethanol respectively, and finally, vacuum drying is carried out at 80 DEG C to obtain a VO2@NDA composite material. Since the conductive poly-1,8-NDA material tightly wraps the inner vanadium dioxide material, the composite material not only has excellent electronic conductivity, but also cannot be dissolved in a water-based electrolyte in a discharge product, and therefore, as a water-based zinc ion battery positive electrode material, the composite material presents significantly improved rate performance and cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of aqueous zinc battery cathode modification technology, specifically relating to a method for preparing an organic polymer composite vanadium-based aqueous zinc battery cathode and its application. Background Technology

[0002] In recent years, aqueous zinc batteries have received widespread attention and have seen rapid development in the field of aqueous rechargeable batteries. On the one hand, zinc is abundant on Earth, offering low cost and environmental friendliness; on the other hand, it boasts a high theoretical capacity (820mAh g / g). -1 The zinc-ion battery exhibits high specific capacity and low redox potential (-0.76V relative to the standard hydrogen electrode). Currently, manganese-based compounds, vanadium-based compounds, Prussian blue analogs, and organic compounds are all designed as cathode materials for aqueous zinc-ion batteries. Among them, vanadium-based compounds are considered promising cathode materials for aqueous zinc-ion batteries due to their high specific capacity. However, problems such as narrow interlayer spacing, low intrinsic conductivity, and vanadium dissolution still limit their further application. Organic electrode materials typically exhibit low electronic conductivity, requiring the addition of large amounts of conductive additives, thus limiting the volumetric specific capacity and specific energy of aqueous zinc-ion batteries. Therefore, developing cathode materials for aqueous zinc-ion batteries with high specific capacity and high stability remains an important research direction for aqueous zinc-ion batteries. Summary of the Invention

[0003] Technical problems to be solved:

[0004] This application addresses the shortcomings of existing technologies by solving technical problems such as poor cycle stability due to the high solubility of vanadium-based oxides in aqueous electrolytes and low energy density due to the low electronic conductivity of organic materials. It provides a method for preparing a vanadium-based aqueous zinc battery cathode composed of organic polymers and its application. Using vanadium pentoxide (V2O5) and diaminonaphthalene (NDA) as raw materials, a VO2@NDA composite material is prepared by a one-step hydrothermal method. This cathode material has a strip-like or flower-like nanosheet structure, which is conducive to ion transport, resulting in excellent rate performance, superior cycle stability, and high specific capacity.

[0005] Technical solution:

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] A method for preparing an organic polymer composite vanadium-based aqueous zinc battery cathode and its application, comprising the following steps:

[0008] Step 1, Synthesis of V2O5 Nanoribbons:

[0009] S1. Under room temperature conditions, weigh 1.2g of ammonium metavanadate (NH4VO3) and 0.6g of oxalic acid (HO2CCO2H) according to the mass-volume ratio and dissolve them in 80mL of deionized water respectively. After stirring thoroughly, a uniform ammonium metavanadate solution and oxalic acid solution are obtained.

[0010] S2. Slowly pour the ammonium metavanadate solution into the oxalic acid solution, stir vigorously for 20-30 minutes, transfer the mixed solution to a hydrothermal reactor, and then place the hydrothermal reactor in an oven at 180°C for 24 hours.

[0011] S3. After cooling to room temperature, the hydrothermal reactor was removed from the oven and then centrifuged. The reactor was washed three times with deionized water and ethanol, respectively. Finally, the product was dried in a vacuum drying oven at 80°C for 12 hours to obtain V2O5 nanoribbons.

[0012] The second step is the synthesis of VO2@NDA:

[0013] Step a: Add 0.4g of V2O5 to 60mL of deionized water according to the mass-volume ratio, and stir vigorously for 1-2 hours to obtain a V2O5 solution;

[0014] Step b: Add 0.2 g of 1,8-diaminonaphthalene (1,8-NDA) to 30 mL of acetonitrile solution according to the mass-volume ratio, stir vigorously to dissolve it, then slowly add V2O5 solution and continue stirring for 2-3 hours;

[0015] Step c: Transfer the mixed solution to a hydrothermal reactor, and then place the hydrothermal reactor in an oven at 140°C for 24 hours;

[0016] Step d: After the reaction mixture is cooled to room temperature, it is centrifuged and washed three times with deionized water and ethanol. The product is then dried in a vacuum drying oven at 70-80℃ for 10 hours to obtain the product, which is denoted as VO2@NDA complex.

[0017] Step 3: Calculate by mass percentage: 60%-80% active material VO2@NDA complex; 10%-30% conductive additive; 10% binder, totaling 100%;

[0018] Step 4: Mix the VO2@NDA complex with conductive additives and binders until homogeneous. Then, add 3 mL of isopropanol dropwise to the mixture to obtain smooth spheres. Form an electrode film by rolling and pressing. Finally, press the electrode film onto the mesh current collector to obtain the positive electrode.

[0019] Furthermore, in the third step, the conductive additive is one or more of acetylene black, Ketjen black KB, activated carbon, mesoporous carbon, graphene, carbon nanotubes, carbon fibers, and conductive carbon black; the binder is one of polytetrafluoroethylene PTFE, polyvinylidene fluoride PVDF, polyacrylonitrile PAN, polyimide PI, perfluorosulfonic acid ionomer Nafion, sodium carboxymethyl cellulose CMC, styrene-butadiene rubber SBR, polyacrylate LA, and polyacrylic acid PAA.

[0020] Furthermore, the binder is polyvinylidene fluoride (PVDF) powder.

[0021] Furthermore, in the fourth step, the mesh current collector is carbon paper or stainless steel mesh.

[0022] This application also discloses the application of vanadium-based organic polymer composite cathodes prepared by any of the above preparation methods in environmentally friendly aqueous zinc-ion batteries or aqueous non-metallic ion batteries.

[0023] Furthermore, the aqueous zinc-ion battery uses a zinc sheet as the negative electrode and a zinc-ion aqueous electrolyte.

[0024] Furthermore, the negative electrode material is one of zinc sheets with a thickness of 0.02 mm, 0.05 mm, or 0.1 mm.

[0025] Furthermore, the zinc ion aqueous electrolyte is one of Zn(CF3SO3)2, ZnSO4, Zn(NO3)2, ZnBr2, ZnCO3, ZnI2, Zn(ClO)4, Zn(CH3COO)2, Zn(BF4)2 and ZnCl2.

[0026] Furthermore, the zinc ion electrolyte contains zinc ions at a concentration of 0.1 mol / L to 20 mol / L.

[0027] Furthermore, a flexible Zn / / VO2@NDA battery was prepared by stacking an organic polymer composite vanadium-based cathode, a glass fiber separator, and a zinc sheet electrode into a structure similar to a "sandwich" and using a 2M Zn(CF3SO3)2 aqueous solution as the electrolyte.

[0028] Explanation of the principle: The superior performance of VO2@NDA materials lies in the uniform coating of the VO2@NDA particles and their excellent crystallinity. Within the substrate structure, NDA and VO2 form chemical bonds, making the composite more stable. When VO2 combines with organic NDA, VO2 is protected by the hydrophobicity of the NDA polymer chains. Simultaneously, the organic coating layer reduces VO2's solubility in aqueous electrolytes by physically restricting its contact with the electrolyte. Doping with organic NDA not only improves the electronic structure of VO2 but also increases the absorption energy of zinc ions, thereby increasing the operating voltage. Furthermore, the interlayer exfoliation of VO2 caused by polymer NDA doping forms ribbon-like or flower-like nanosheet structures. These nanostructures increase the contact area between the active material and the electrolyte, thereby improving ion transport speed and ultimately enhancing rate performance and charge / discharge efficiency.

[0029] Beneficial effects:

[0030] This application provides a method for preparing an organic polymer composite vanadium-based aqueous zinc battery cathode and its application, which has the following advantages compared with the prior art:

[0031] 1. This application mainly addresses the problems existing in the cathode of current aqueous zinc batteries, and is simple to prepare, low in cost, and can be mass-produced, thereby realizing industrialization;

[0032] 2. This application discloses a method for preparing a vanadium-based aqueous zinc battery cathode composed of organic polymer composites. The doping of organic NDA can not only improve the electronic structure of VO2, but also increase the absorption energy of zinc ions, thereby improving the working voltage.

[0033] 3. The VO2@NDA zinc cathode synthesized in this application operates at a low current density of 0.5 Ag. -1 It can be stably cycled 200 times, with a discharge capacity of 410mAh g. -1 It exhibits high capacity properties;

[0034] 4. The VO2@NDA zinc cathode synthesized in this application is at 10Ag -1 Even at high current densities, it can still display 200mAh g. -1 It has the capacity and can stably cycle for 8300 times with a capacity retention rate of 93%;

[0035] 5. The VO2@NDA zinc cathode synthesized in this application operates at current densities from 0.5 Ag. -1 Gradually increase to 20 Ag -1 At the same time, the charging and discharging platform remained consistent, even at 20Ag. -1 At current density, it still shows 140 mAh g -1 Its specific capacity exhibits excellent rate performance. Attached Figure Description

[0036] Figure 1 This is a SEM image of the vanadium-based aqueous zinc battery cathode composed of organic polymer composites of this application.

[0037] Figure 2 This is the XRD powder diffraction pattern of the vanadium-based material composed of organic polymers in this application;

[0038] Figure 3 The current density under this application is 0.5Ag. -1 The cycle performance diagram shows that it can stably cycle for 200 cycles, with a discharge capacity of 410mAh g. -1 The capacity retention rate was 86%.

[0039] Figure 4 This application is based on a current density of 10Ag -1 The cycle performance diagram shows that it can stably cycle for 8300 cycles, with a discharge capacity of 200mAh g. -1 The capacity retention rate was 93%.

[0040] Figure 5 This application is for current densities from 0.5Ag -1 Gradually increase to 20 Ag -1 The charge / discharge curves at the specified rates. Detailed Implementation

[0041] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0042] Example 1

[0043] A method for preparing a vanadium-based aqueous zinc battery cathode composed of an organic polymer composite, comprising the following steps:

[0044] Step 1, Synthesis of V2O5 Nanoribbons:

[0045] S1. Under room temperature conditions, weigh 1.2g of ammonium metavanadate (NH4VO3) and 0.6g of oxalic acid (HO2CCO2H) according to the mass-volume ratio and dissolve them in 80mL of deionized water respectively. After stirring thoroughly, a uniform ammonium metavanadate solution and oxalic acid solution are obtained.

[0046] S2. Slowly pour the ammonium metavanadate solution into the oxalic acid solution, stir vigorously for 20 minutes, transfer the mixed solution to the hydrothermal reactor, and then place the hydrothermal reactor in an oven at 180°C for 24 hours.

[0047] S3. After cooling to room temperature, the hydrothermal reactor was removed from the oven and then centrifuged. The reactor was washed three times with deionized water and ethanol, respectively. Finally, the product was dried in a vacuum drying oven at 80°C for 12 hours to obtain V2O5 nanoribbons.

[0048] The second step is the synthesis of VO2@NDA:

[0049] Step a: Add 0.4g of V2O5 to 60mL of deionized water according to the mass-volume ratio, and stir vigorously for 2h to obtain a V2O5 solution;

[0050] Step b: Add 0.2 g of 1,8-diaminonaphthalene (1,8-NDA) to 30 mL of acetonitrile solution according to the mass-volume ratio, stir vigorously to dissolve it, then slowly add V2O5 solution and continue stirring for 3 h;

[0051] Step c: Transfer the mixed solution to a hydrothermal reactor, and then place the hydrothermal reactor in an oven at 140°C for 24 hours;

[0052] Step d: After the reaction mixture is cooled to room temperature, it is centrifuged and washed three times with deionized water and ethanol respectively. The product is dried in a vacuum drying oven at 80°C for 10 hours to obtain the product, which is denoted as VO2@NDA complex.

[0053] Step 3: By weight percentage: VO2@NDA complex 60%; conductive additive KB 30%; PTFE 10%;

[0054] Step 4: Mix the VO2@NDA complex with conductive additives and binders evenly, then add 2 mL of isopropanol to the mixture until smooth spheres are formed. The electrode film is then formed by rolling and pressing, and finally the electrode film is pressed onto the current collector titanium mesh to obtain the positive electrode.

[0055] The application of an organic polymer composite vanadium-based aqueous zinc battery cathode in environmentally friendly aqueous zinc batteries, using a metallic zinc sheet as the negative electrode and an aqueous zinc ion electrolyte. The assembly sequence is: negative electrode shell, 0.02mm zinc sheet, Whatman glass fiber separator, organic polymer composite vanadium-based cathode, and cathode shell. The electrolyte is 1 mol·L⁻¹. -1 A ZnSO4 aqueous solution was used as the electrolyte, and the cells were sealed and assembled into CR2032 button cells using a battery packaging machine. These are denoted as Zn / / VO2@NDA oxide button cells.

[0056] Example 2

[0057] A method for preparing a vanadium-based aqueous zinc battery cathode composed of an organic polymer composite, comprising the following steps:

[0058] Step 1, Synthesis of V2O5 Nanoribbons:

[0059] S1. Under room temperature conditions, weigh 1.2g of ammonium metavanadate (NH4VO3) and 0.6g of oxalic acid (HO2CCO2H) according to the mass-volume ratio and dissolve them in 80mL of deionized water respectively. After stirring thoroughly, a uniform ammonium metavanadate solution and oxalic acid solution are obtained.

[0060] S2. Slowly pour the ammonium metavanadate solution into the oxalic acid solution, stir vigorously for 30 minutes, transfer the mixed solution to a hydrothermal reactor, and then place the hydrothermal reactor in an oven at 180°C for 24 hours.

[0061] S3. After cooling to room temperature, the hydrothermal reactor was removed from the oven and then centrifuged. The reactor was washed three times with deionized water and ethanol, respectively. Finally, the product was dried in a vacuum drying oven at 80°C for 12 hours to obtain V2O5 nanoribbons.

[0062] The second step is the synthesis of VO2@NDA:

[0063] Step a: Add 0.4g of V2O5 to 60mL of deionized water according to the mass-volume ratio, and stir vigorously for 3h to obtain a V2O5 solution;

[0064] Step b: Add 0.2 g of 1,8-diaminonaphthalene (1,8-NDA) to 30 mL of acetonitrile solution according to the mass-volume ratio, stir vigorously to dissolve it, then slowly add V2O5 solution and continue stirring for 3 h;

[0065] Step c: Transfer the mixed solution to a hydrothermal reactor, and then place the hydrothermal reactor in an oven at 140°C for 24 hours;

[0066] Step d: After the reaction mixture is cooled to room temperature, it is centrifuged and washed three times with deionized water and ethanol respectively. The product is dried in a vacuum drying oven at 80°C for 10 hours to obtain the product, which is denoted as VO2@NDA complex.

[0067] Step 3: By weight percentage: VO2@NDA complex 60%; conductive additive KB 30%; PTFE 10%;

[0068] Step 4: Mix the VO2@NDA complex with conductive additives and binders evenly, then add 2 mL of isopropanol to the mixture until smooth spheres are formed. The electrode film is then formed by rolling and pressing, and finally the electrode film is pressed onto the current collector nickel mesh to obtain the positive electrode.

[0069] The application of vanadium-based aqueous zinc battery cathodes composed of organic polymers in environmentally friendly aqueous batteries involves stacking a VO2@NDA composite cathode, a glass fiber separator, and a zinc sheet electrode together to form a "sandwich" structure, using 2 mol / L...-1 A flexible Zn / / VO2@NDA battery was prepared using an aqueous ZnSO4 solution as the electrolyte and a vacuum sealing machine.

[0070] Example 3

[0071] A method for preparing a vanadium-based aqueous zinc battery cathode composed of an organic polymer composite, comprising the following steps:

[0072] Step 1, Synthesis of V2O5 Nanoribbons:

[0073] S1. Under room temperature conditions, weigh 1.2g of ammonium metavanadate (NH4VO3) and 0.6g of oxalic acid (HO2CCO2H) according to the mass-volume ratio and dissolve them in 80mL of deionized water respectively. After stirring thoroughly, a uniform ammonium metavanadate solution and oxalic acid solution are obtained.

[0074] S2. Slowly pour the ammonium metavanadate solution into the oxalic acid solution, stir vigorously for 30 minutes, transfer the mixed solution to a hydrothermal reactor, and then place the hydrothermal reactor in an oven at 180°C for 24 hours.

[0075] S3. After cooling to room temperature, the hydrothermal reactor was removed from the oven and then centrifuged. The reactor was washed three times with deionized water and ethanol, respectively. Finally, the product was dried in a vacuum drying oven at 80°C for 12 hours to obtain V2O5 nanoribbons.

[0076] The second step is the synthesis of VO2@NDA:

[0077] Step a: Add 0.4g of V2O5 to 60mL of deionized water according to the mass-volume ratio, and stir vigorously for 3h to obtain a V2O5 solution;

[0078] Step b: Add 0.2 g of 1,8-diaminonaphthalene (1,8-NDA) to 30 mL of acetonitrile solution according to the mass-volume ratio, stir vigorously to dissolve it, then slowly add V2O5 solution and continue stirring for 3 h;

[0079] Step c: Transfer the mixed solution to a hydrothermal reactor, and then place the hydrothermal reactor in an oven at 140°C for 24 hours;

[0080] Step d: After the reaction mixture is cooled to room temperature, it is centrifuged and washed three times with deionized water and ethanol respectively. The product is dried in a vacuum drying oven at 80°C for 10 hours to obtain the product, which is denoted as VO2@NDA complex.

[0081] Step 3: By weight percentage: 70% active material VO2@NDA complex; 20% conductive additive carbon black; 10% PTFE;

[0082] Step 4: Mix the VO2@NDA composite with conductive additives and binders evenly, add 2 mL of ethanol to the mixture until smooth spheres are formed, and form an electrode film by rolling. Finally, press the electrode film onto the current collector titanium mesh to obtain the positive electrode.

[0083] The application of an organic polymer composite vanadium-based aqueous zinc battery cathode in environmentally friendly aqueous batteries, using a metallic zinc sheet as the negative electrode and an aqueous zinc ion electrolyte. The assembly sequence is: negative electrode shell, 0.05mm zinc sheet, Whatman glass fiber separator, VO2@NDA composite cathode, and cathode shell. -1 Using an aqueous solution of ZnSO4 as the electrolyte, the cells are sealed and assembled into CR2032 button cells using a battery packaging machine. This is designated as a Zn / / VO2@NDA composite button cell.

[0084] Example 4

[0085] A method for preparing a vanadium-based aqueous zinc battery cathode composed of an organic polymer composite, comprising the following steps:

[0086] Step 1, Synthesis of V2O5 Nanoribbons:

[0087] S1. Under room temperature conditions, weigh 1.2g of ammonium metavanadate (NH4VO3) and 0.6g of oxalic acid (HO2CCO2H) according to the mass-volume ratio and dissolve them in 80mL of deionized water respectively. After stirring thoroughly, a uniform ammonium metavanadate solution and oxalic acid solution are obtained.

[0088] S2. Slowly pour the ammonium metavanadate solution into the oxalic acid solution, stir vigorously for 20 minutes, transfer the mixed solution to the hydrothermal reactor, and then place the hydrothermal reactor in an oven at 180°C for 24 hours.

[0089] S3. After cooling to room temperature, the hydrothermal reactor was removed from the oven and then centrifuged. The reactor was washed three times with deionized water and ethanol, respectively. Finally, the product was dried in a vacuum drying oven at 80°C for 12 hours to obtain V2O5 nanoribbons.

[0090] The second step is the synthesis of VO2@NDA:

[0091] Step a: Add 0.4g of V2O5 to 60mL of deionized water according to the mass-volume ratio, and stir vigorously for 3h to obtain a V2O5 solution;

[0092] Step b: Add 0.2 g of 1,8-diaminonaphthalene (1,8-NDA) to 30 mL of acetonitrile solution according to the mass-volume ratio, stir vigorously to dissolve it, then slowly add V2O5 solution and continue stirring for 2 h;

[0093] Step c: Transfer the mixed solution to a hydrothermal reactor, and then place the hydrothermal reactor in an oven at 140°C for 24 hours;

[0094] Step d: After the reaction mixture is cooled to room temperature, it is centrifuged and washed three times with deionized water and ethanol respectively. The product is dried in a vacuum drying oven at 80°C for 10 hours to obtain the product, which is denoted as VO2@NDA complex.

[0095] Step 3: By mass percentage: 70% active material VO2@NDA complex; 20% conductive additive acetylene black; 10% PTFE;

[0096] Step 4: Mix the VO2@NDA complex with conductive additives and binders evenly, add 2 mL of isopropanol to the mixture until smooth spheres are formed, and form an electrode film by rolling. Finally, press the electrode film onto a current collector stainless steel mesh to obtain the positive electrode.

[0097] The application of an organic polymer composite vanadium-based aqueous zinc battery cathode in environmentally friendly aqueous batteries, using a metallic zinc sheet as the negative electrode and an aqueous zinc ion electrolyte. The assembly sequence is: negative electrode shell, 0.05mm zinc sheet, glass fiber separator, VO2@NDA composite cathode, and cathode shell. A 1 mol / L... -1 A Zn(BF4)2 aqueous solution was used as the electrolyte, and the cells were sealed and assembled into CR2032 button cells using a battery packaging machine. These are denoted as Zn / / VO2@NDA button cells.

[0098] Scanning electron microscopy (SEM) characterization:

[0099] The synthesized VO2@NDA was subjected to SEM testing to characterize its morphology, such as... Figure 1 As shown, the synthesized VO2@NDA exhibits a nanosheet structure.

[0100] XRD test:

[0101] The synthesized VO2@NDA was subjected to XRD testing, such as... Figure 2 The position and intensity of the characteristic peaks highly match those of the standard VO2 card, proving that V2O5 has been completely converted into VO2.

[0102] Cyclic stability test:

[0103] like Figure 3 The figure shows the current density at 5Ag. -1 The following cycle graph shows that the Zn / / VO2@NDA battery has a capacity of 250mAh g. -1 The discharge specific capacity remains at 150 mAh g after 260 cycles. -1 The capacity retention rate is 60%.

[0104] Long-cycle stability test:

[0105] Figure 4 The figure shows the current density at 10Ag. -1 The cycle performance diagram below shows a cycle life of 8300 cycles and a capacity retention rate of up to 50%.

[0106] Ratio performance test:

[0107] Figure 5 This is at a current density of 0.5Ag -1 Gradually increase to 20 Ag -1 The charge-discharge curves at various rates show that the VO2@NDA cathode exhibits excellent rate performance at 20Ag. -1 Even at high current densities, the battery can still achieve a capacity of 140mAh g. -1 Its discharge specific capacity exhibits excellent rate performance.

[0108] The examples described above are for illustrative purposes only and are not intended to limit the process. Those skilled in the art can easily modify the process flow or transfer it to other applications without inventive step. If these modifications also fall under the category of similar claims or technologies of this invention, then the intent of the invention also includes these modifications.

Claims

1. A method for preparing a vanadium-based aqueous zinc battery cathode composed of an organic polymer composite, characterized in that, The steps are as follows: Step 1, Synthesis of V2O5 Nanoribbons: S1. Under room temperature conditions, weigh 1.2g of ammonium metavanadate (NH4VO3) and 0.6g of oxalic acid (HO2CCO2H) according to the mass-volume ratio and dissolve them in 80mL of deionized water respectively. After stirring thoroughly, a uniform ammonium metavanadate solution and oxalic acid solution are obtained. S2. Slowly pour the ammonium metavanadate solution into the oxalic acid solution, stir vigorously for 20-30 minutes, transfer the mixed solution to a hydrothermal reactor, and then place the hydrothermal reactor in an oven at 180°C for 24 hours. S3. After cooling to room temperature, the hydrothermal reactor was removed from the oven and then centrifuged. The reactor was washed three times with deionized water and ethanol, respectively. Finally, the product was dried in a vacuum drying oven at 80°C for 12 hours to obtain V2O5 nanoribbons. The second step is the synthesis of VO2@NDA: Step a: Add 0.4g of V2O5 to 60mL of deionized water according to the mass-volume ratio, and stir vigorously for 1-2 hours to obtain a V2O5 solution; Step b: Add 0.2 g of 1,8-diaminonaphthalene (1,8-NDA) to 30 mL of acetonitrile solution according to the mass-volume ratio, stir vigorously to dissolve it, then slowly add V2O5 solution and continue stirring for 2-3 hours; Step c: Transfer the mixed solution to a hydrothermal reactor, and then place the hydrothermal reactor in an oven at 140°C for 24 hours; Step d: After the reaction mixture is cooled to room temperature, it is centrifuged and washed three times with deionized water and ethanol. The product is then dried in a vacuum drying oven at 70-80℃ for 10 hours to obtain the product, which is denoted as VO2@NDA complex. Step 3: Calculate by mass percentage: 60%-80% active material VO2@NDA complex; 10%-30% conductive additive; 10% binder, totaling 100%; Step 4: Mix the VO2@NDA complex with conductive additives and binders until homogeneous. Then, add 3 mL of isopropanol dropwise to the mixture to obtain smooth spheres. Form an electrode film by rolling and pressing. Finally, press the electrode film onto the mesh current collector to obtain the positive electrode.

2. The method for preparing the vanadium-based aqueous zinc battery cathode composited with organic polymer according to claim 1, characterized in that: In the third step, the conductive additive is one or more of acetylene black, Ketjen black KB, activated carbon, mesoporous carbon, graphene, carbon nanotubes, carbon fibers, and conductive carbon black; the binder is one of polytetrafluoroethylene PTFE, polyvinylidene fluoride PVDF, polyacrylonitrile PAN, polyimide PI, perfluorosulfonic acid ionomer Nafion, sodium carboxymethyl cellulose CMC, styrene-butadiene rubber SBR, polyacrylate LA, and polyacrylic acid PAA.

3. The method for preparing the vanadium-based aqueous zinc battery cathode composited with organic polymer according to claim 2, characterized in that: The binder is polyvinylidene fluoride (PVDF) powder.

4. The method for preparing the vanadium-based aqueous zinc battery cathode composited with organic polymer according to claim 1, characterized in that: In the fourth step, the mesh current collector is made of carbon paper or stainless steel mesh.

5. The application of an organic polymer composite vanadium-based aqueous zinc battery cathode prepared by any of the preparation methods of claims 1-4 in aqueous zinc batteries or flexible zinc batteries.

6. The application according to claim 5, characterized in that: The aqueous zinc battery or flexible zinc battery uses metallic zinc sheet as the negative electrode material and zinc ion aqueous electrolyte as the electrolyte.

7. The application according to claim 6, characterized in that: The negative electrode material is one of zinc sheets with a thickness of 0.02 mm, 0.05 mm, or 0.1 mm.

8. The application according to claim 6, characterized in that: The zinc ion aqueous electrolyte is one of Zn(CF3SO3)2, ZnSO4, Zn(NO3)2, ZnBr2, ZnCO3, ZnI2, Zn(ClO)4, Zn(CH3COO)2, Zn(BF4)2 and ZnCl2.

9. The application according to claim 8, characterized in that: The zinc ion aqueous electrolyte contains zinc ions at a concentration of 0.1 mol / L to 20 mol / L.

10. The application according to claim 5, characterized in that: A flexible Zn / / VO2@NDA battery was prepared by stacking an organic polymer composite vanadium-based aqueous zinc battery cathode, a glass fiber separator, and a zinc sheet electrode into a structure similar to a "sandwich" and using a 2M Zn(CF3SO3)2 aqueous solution as the electrolyte.

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