Zinc ion battery positive electrode material, preparation method thereof and zinc ion battery

Abstract

The application belongs to the technical field of batteries, and particularly relates to a zinc ion battery positive electrode material, a preparation method thereof and a zinc ion battery. A redox active aromatic molecule containing conjugated pi electrons is grafted to the surface of a nitrogen-doped carbon-based material through pi-pi interaction, and a vanadium-based oxide positive electrode material is coated with the redox active carbon-based material. The redox active carbon-based material has a positive effect on excited pseudo-capacitance charge storage, and the charge storage dominant mechanism of the vanadium-based positive electrode material is pseudo-capacitance storage. Thanks to the pseudo-capacitance storage mechanism, the vanadium-based positive electrode material has excellent rate performance. Meanwhile, the carbon-based material has a large specific surface area and a flexible structure, which not only improves the electrode reaction kinetics, but also provides buffering and protection for the volume change of the vanadium-based positive electrode material, enhances the structural stability of the vanadium-based positive electrode material, and thus significantly improves the cycle stability and capacity of the vanadium-based positive electrode material.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a zinc-ion battery cathode material, its preparation method, and a zinc-ion battery. Background Technology

[0002] The development of lithium-ion batteries has been constrained by factors such as low lithium resource reserves, high safety risks, and rising costs. Rechargeable aqueous zinc-ion batteries, however, are considered a potential alternative due to their high capacity, low cost, and high safety. Vanadium-based oxides with different structures and multiple valence states are highly promising cathode materials for aqueous zinc-ion batteries. However, due to the limited availability of Zn... 2+ The strong electrostatic interaction between Zn and vanadium-based oxides leads to... 2+ Storage is severely limited by diffusion; these vanadium-based oxides generally suffer from poor conductivity and sluggish kinetics. Meanwhile, Zn... 2+ Insertion and extraction can cause phase transitions and structural collapse in the host material, making it difficult for aqueous zinc-ion batteries to meet the energy and power densities required for practical applications. Currently, to alleviate these problems, the main optimization strategies include pre-insertion and doping. While these methods improve energy and rate performance to some extent, they essentially do not address the fundamental limitations of Zn... 2+ Currently, charge storage is still diffusion-controlled and has not reached the practical level for large-scale applications. Pseudocapacitive storage, however, stores charge through a Faraday reaction, exhibiting high energy density and being diffusion-independent. Its power density and cycle life are comparable to supercapacitors, presenting a new opportunity for achieving high-energy and high-power-density aqueous zinc-ion batteries. Therefore, exciting the pseudocapacitive behavior of vanadium-based oxides can simultaneously improve the energy and power density of aqueous zinc-ion batteries.

[0003] Carbon-based materials are among the most successful energy storage materials to date, ideal for supercapacitors, and widely used in zinc-ion battery systems for coating and improving the structural stability of cathode materials. Utilizing carbon-based materials to excite the pseudocapacitive behavior of vanadium-based cathode materials is a promising area of ​​research. Summary of the Invention

[0004] This invention aims to provide a zinc-ion battery cathode material, its preparation method, and a zinc-ion battery. By coating a vanadium-based oxide cathode material with a carbon-based material having multiple redox active sites, the pseudocapacitive mechanism of the vanadium-based oxide cathode material is activated, thereby improving the energy density and power density of the aqueous zinc-ion battery.

[0005] According to the technical solution of the present invention, the preparation method of the zinc-ion battery cathode material includes the following steps:

[0006] S1: A hydrogel-like film is formed by coating carbon-based materials, NaCl, urea and (NH4)2CO3 aqueous solution, and then heated to react after dehydration and drying to obtain nitrogen-doped carbon-based materials;

[0007] S2: Immerse the nitrogen-doped carbon-based material in an aqueous solution containing aromatics, wherein the aromatics are oxidizing aromatics, to obtain a carbon-based material with redox activity;

[0008] S3: Disperse the redox-active carbon-based material in a vanadium-based oxide solution and freeze-dry to obtain the zinc-ion battery cathode material.

[0009] This invention grafts redox-active aromatic molecules containing conjugated π electrons onto the surface of nitrogen-doped carbon-based materials via π-π interactions, thereby coating vanadium-based oxide cathode materials with redox-active carbon-based materials. This reduces the energy barrier for electron transfer to the cathode material, promotes the Faraday reaction, and stimulates the pseudocapacitive mechanism of the vanadium-based oxide cathode material, while simultaneously improving the energy density and power density of aqueous zinc-ion batteries.

[0010] Among these advantages, nitrogen atom electronegativity (3.04) is close to that of carbon atom (2.55), allowing nitrogen doping to act as an electron donor and enabling nitrogen-doped carbon-based materials to exhibit more superior properties compared to pure carbon-based materials. It can open the band gap and adjust the conductivity type, alter the electronic structure, and increase the free carrier density, thereby improving the conductivity and stability of carbon-based materials. Furthermore, introducing nitrogen-containing structures into the carbon network of carbon-based materials can increase the active sites adsorbed on the carbon surface, thus enhancing the interaction between metal particles and carbon-based materials.

[0011] Furthermore, the carbon-based material is selected from one or more of soft carbon, hard carbon, graphite, graphene, and graphene oxide.

[0012] Furthermore, in step S1, the mass ratio of carbon-based material, NaCl, urea and (NH4)2CO3 is 7-13:28-33:28-33:28-33.

[0013] Furthermore, in step S1, NaCl has a gelling effect on carbon-based materials, and the aqueous solution of carbon-based materials, NaCl, urea, and (NH4)2CO3 presents a viscous aqueous solution. This viscous aqueous solution is coated onto a substrate (such as a glass slide) to prepare a hydrogel-like film.

[0014] Furthermore, in step S1, the hydrogel-like film is immersed in acetone to extract water and then naturally dried in the air.

[0015] Furthermore, in step S1, the heating reaction is carried out at a temperature of 160–200°C for 2–4 hours.

[0016] Specifically, in a clamped state (such as when two glass slides are pressed together), the dehydrated and dried hydrogel-like film is placed in a heated reaction vessel (such as a high-pressure reactor lined with polytetrafluoroethylene) containing a diluted ammonia solution for heating and reaction.

[0017] Furthermore, the oxidizing aromatic compound is selected from one or more of phenylenediamine and its isomers, naphthylenediamine and its isomers, aminophenol and its isomers, and phenylenediamine compounds.

[0018] Furthermore, the oxidizing aromatic compound can be 4-aminophenol, 4,4'-phenylene oxide, 4,4'-thioiodophenylene diamine, 1,5-naphthyldiamine, 2-aminophenol, etc.

[0019] Furthermore, in step S2, the concentration of aromatics in the aqueous solution is 0.05–0.07 mol / L; the volume of the aqueous solution containing aromatics required for soaking 50–100 mg of carbon-based material is 100–200 mL.

[0020] Specifically, aromatic compounds with oxidizing activity are dissolved in water at 60–80°C to obtain an aqueous solution containing aromatic compounds.

[0021] Furthermore, in step S2, the soaking time is 5-8 hours and the temperature is 60-80°C.

[0022] Furthermore, the vanadium-based oxide is selected from one or more of V2O5, VO2, V3O7, V6O13, etc.; for example, it can be a V3O7 / V6O13 with a mass ratio of 3-7:3-7. 13 Powder, or V2O5 powder, etc.

[0023] The solvent for the vanadium-based oxide solution is a mixture of alcohol and water; the volume ratio of alcohol to water in the mixture is 1-3:1-3; the alcohol is methanol, ethanol, isopropanol, or n-butanol.

[0024] Specifically, vanadium-based oxide is added to a mixed solution of alcohol and water and sonicated for 2-4 hours to obtain the vanadium-based oxide solution.

[0025] Furthermore, in step S3, the mass ratio of the redox-active carbon-based material to the vanadium-based oxide is 3-6:20-40. In a specific embodiment, the amount of vanadium-based oxide can be 100-200 mg, and the amount of the redox-active carbon-based material can be 15-30 mg.

[0026] Furthermore, in step S3, the reaction is further subjected to ultrasonication for 0.5 to 1 hour before stirring.

[0027] The temperature of the stirring reaction is 40–60℃, and the time is 12–24 h.

[0028] Furthermore, in step S3, the specific operation of freeze drying is as follows: freeze under liquid nitrogen for 10-30 minutes, and then freeze dry in a freeze dryer for 48-72 hours.

[0029] A second aspect of the present invention provides a zinc-ion battery cathode material prepared by the above-described preparation method.

[0030] The zinc-ion battery positive electrode material can be used to prepare the positive electrode material layer of the positive electrode sheet. Specifically, the zinc-ion battery positive electrode material is mixed with a conductive agent, a binder and a solvent to form a slurry, which is then coated onto the surface of the positive electrode current collector and dried to obtain a positive electrode sheet containing the zinc-ion battery positive electrode material.

[0031] Furthermore, the mass ratio of the zinc-ion battery positive electrode material, conductive agent, and binder is 7-8:1-2:1.

[0032] Furthermore, the conductive agent may be one or more of acetylene black, Ketjen black, SuperP, carbon fiber, carbon nanotubes, etc.; the binder may be one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), etc.; the solvent may be N-methylpyrrolidone (NMP), etc.; and the positive electrode current collector may be one of titanium foil, stainless steel, carbon paper, carbon cloth, graphene paper, etc.

[0033] Furthermore, the drying is carried out in an oven at a temperature of 60–120°C for a time of 6–48 hours.

[0034] A third aspect of the present invention provides a zinc-ion battery comprising the above-described positive electrode.

[0035] Specifically, the zinc-ion battery includes the positive electrode, the electrolyte, and the zinc negative electrode.

[0036] Furthermore, the zinc-ion battery can be a button cell; the steps of assembling the zinc-ion battery include: stacking the positive electrode, electrolyte, glass fiber membrane, zinc negative electrode, spring sheet, and gasket in sequence to assemble the button cell.

[0037] Furthermore, the electrolyte may be one or more of the following: zinc sulfate aqueous solution, zinc trifluoromethanesulfonate aqueous solution, zinc nitrate aqueous solution, or other water-soluble zinc salts.

[0038] The technical solution of the present invention has the following advantages compared with the prior art:

[0039] In this invention, redox-active carbon-based materials play a positive role in activating pseudocapacitive charge storage, and the dominant charge storage mechanism of vanadium-based cathode materials is pseudocapacitive storage. Benefiting from this pseudocapacitive storage mechanism, vanadium-based cathode materials exhibit excellent rate performance at 10 Ag. -1 At a current density, the capacity reaches as high as 297mAh g. -1 ;

[0040] Meanwhile, carbon-based materials have a large specific surface area and a flexible structure, which not only improves the electrode reaction kinetics, but also provides a buffer and protection for the volume changes of vanadium-based cathode materials, enhancing the structural stability of vanadium-based cathode materials, thereby significantly improving the cycle stability and capacity of vanadium-based cathode materials. Attached Figure Description

[0041] Figure 1 The redox activated carbon-based material obtained in Example 1 is used to coat V3O7 / V6O 13 SEM image of the cathode material.

[0042] Figure 2 The redox activated carbon-based material obtained in Example 1 is used to coat V3O7 / V6O 13 TEM image of the cathode material.

[0043] Figure 3 The redox activated carbon-based material obtained in Example 1 is used to coat V3O7 / V6O 13 0.2–1.0 mVs of cathode material -1 Capacitor contribution rate at sweep speed. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0045] This invention provides a zinc-ion battery cathode material, which excites pseudocapacitive behavior by coating an aqueous zinc-ion battery cathode material with a carbon-based material having multiple active sites. The preparation method is as follows:

[0046] Step 1: A viscous aqueous solution of carbon-based material, NaCl, urea, and (NH4)2CO3 in a mass ratio of 7–13:28–33:28–33:28–33 is coated onto a glass slide to prepare a hydrogel-like film. The film is then immersed in acetone to extract water. After natural air drying, the composite film is pressed between two glass slides and transferred to a high-pressure reactor lined with polytetrafluoroethylene and containing a diluted ammonia solution. The reaction is carried out at 160–200°C for 2–4 hours. After cooling, deionization cleaning is performed to obtain nitrogen-doped carbon-based material.

[0047] Aromatic molecules with oxidizing activity are dissolved in water at 60–80°C to form a solution with a concentration of 0.05–0.07 mol / L. Nitrogen-doped carbon-based materials are then immersed in this solution and soaked at 60–80°C for 5–8 hours, allowing the aromatic molecules to spontaneously adsorb onto the carbon-based materials through π-π interactions. The materials are then repeatedly rinsed with water to obtain carbon-based materials with redox activity.

[0048] Step 2: Place vanadium-based oxide, deionized water, and ethanol into a glass bottle and sonicate for 2–4 hours. Then add the redox-active carbon-based material obtained in Step 1 and sonicate again for 0.5–1 hour. Finally, place the glass bottle in a water bath at 40–60°C and stir for 12–24 hours. The mass ratio of vanadium-based oxide to redox-active carbon-based material is 20–40:3–6.

[0049] Step 3: Freeze the product in liquid nitrogen for 10-30 minutes, then dry it in a freeze dryer for 48-72 hours to obtain a redox-active carbon-based material coated with vanadium-based oxide as a cathode material (zinc-ion battery cathode material).

[0050] This zinc-ion battery cathode material can be used to prepare cathode sheets. Specifically, it is mixed with a conductive agent, a binder, and a solvent to form a slurry, which is then coated onto the surface of the cathode current collector and dried to obtain a zinc-ion cathode sheet.

[0051] The resulting zinc-ion positive electrode sheet can be used to prepare zinc-ion batteries, such as zinc-ion button batteries.

[0052] Example 1:

[0053] A viscous aqueous solution of graphene, NaCl, urea, and (NH4)2CO3 (the amount of water being 2-3 times the total mass of graphene, NaCl, urea, and (NH4)2CO3, hereinafter the same) was coated onto a glass slide in a mass ratio of 10:30:30:30 to prepare a hydrogel-like film. The film was then immersed in acetone to extract the water. After air drying, the composite film was pressed between two glass slides and then transferred to a high-pressure reactor lined with polytetrafluoroethylene and containing a diluted ammonia solution. The reactor was reacted at 180°C for 3 hours. After cooling, deionization cleaning was performed to obtain nitrogen-doped carbon-based material.

[0054] 4-Aminophenol was dissolved in a 0.06 mol / L deionized water solution at 60 °C. Nitrogen-doped carbon-based material was then immersed in the solution at 60 °C for 6 hours. Afterward, it was repeatedly rinsed with deionized water to obtain a carbon-based material with redox activity.

[0055] 100mg of V3O7 / V6O 13 Powder (V3O7 and V6O) 13The mass ratio of the two components was 1:1 (the same applies below). 1 mL of deionized water and 1 mL of ethanol were placed in a glass bottle and sonicated for 2 hours. Then, 15 mg of redox-active carbon-based material was added, and the mixture was sonicated again for 30 minutes. The glass bottle was then placed in a 50°C water bath and stirred for 12 hours. The product was frozen in liquid nitrogen for 10 minutes and then dried in a freeze dryer for 48 hours to obtain redox-active carbon-based material coated V3O7 / V6O. 13 The positive electrode material.

[0056] SEM of the cathode material Figure 1 ) and TEM Figure 2 Tests revealed that the redox activated carbon-based material was coated with V3O7 / V6O like a "thin veil". 13 .

[0057] V3O7 / V6O were coated with redox activated carbon-based materials. 13 A positive electrode was prepared using active material, SuperP as conductive agent, PVDF as binder, and NMP as solvent (the mass ratio of active material, conductive agent, and binder was 7.5:1.5:1, the same below). Then, the positive electrode, zinc sulfate electrolyte, glass fiber membrane, zinc negative electrode, spring sheet, and gasket were assembled into a button cell.

[0058] Perform CV testing on the battery and calculate the pseudocapacitance. Figure 3 (), at scan rates of 0.2, 0.4, 0.6, 0.8 and 1.0 mVs -1 At that time, the contribution of pseudocapacitance to the total capacitance was as high as 85.08%, 88.39%, 90.63%, 93.15%, and 93.73%.

[0059] Example 2:

[0060] A hydrogel-like film was prepared by coating a viscous aqueous solution of graphene oxide, NaCl, urea, and (NH4)2CO3 onto a glass slide in a mass ratio of 13:29:29:29. The film was then immersed in acetone to extract water. After air drying, the composite film was pressed between two glass slides and transferred to a high-pressure reactor lined with polytetrafluoroethylene and containing a diluted ammonia solution. The reactor was reacted at 200°C for 2 hours. After cooling, the film was cleaned with deionized water to obtain nitrogen-doped carbon-based material.

[0061] 4,4'-phenylenediamine oxide was dissolved in a deionized water solution at 80°C, with a concentration of 0.07 mol / L. Nitrogen-doped carbon-based material was then immersed in the solution at 80°C for 5 hours. Afterward, it was repeatedly rinsed with deionized water to obtain a carbon-based material with redox activity.

[0062] 150mg of V3O7 / V6O 13The powder, 2 mL of deionized water, and 2 mL of ethanol were placed in a glass bottle and sonicated for 3 hours. Then, 20 mg of redox-active carbon-based material was added, and the mixture was sonicated again for 45 minutes. The glass bottle was then placed in a 40°C water bath and stirred for 18 hours. The product was then frozen in liquid nitrogen for 20 minutes and then dried in a freeze dryer for 60 hours to obtain redox-active carbon-based material coated V3O7 / V6O. 13 The positive electrode material.

[0063] V3O7 / V6O were coated with redox activated carbon-based materials. 13 A positive electrode is prepared using Ketjen black as the active material, PVDF as the binder, and NMP as the solvent. Then, the positive electrode, zinc trifluoromethanesulfonate electrolyte, glass fiber separator, zinc negative electrode, spring sheet, and gasket are assembled into a button cell.

[0064] Example 3:

[0065] A hydrogel-like film was prepared by coating a viscous aqueous solution of soft carbon, NaCl, urea, and (NH4)2CO3 onto a glass slide in a mass ratio of 7:31:31:31. The film was then immersed in acetone to extract water. After air drying, the composite film was pressed between two glass slides and transferred to a high-pressure reactor lined with polytetrafluoroethylene and containing a diluted ammonia solution. The reactor was reacted at 160°C for 4 hours. After cooling, the film was cleaned with deionized water to obtain nitrogen-doped carbon-based material.

[0066] 4,4'-Thioiodophenyldiamine was dissolved in a 0.06 mol / L deionized water solution at 70 °C. Nitrogen-doped carbon-based materials were then immersed in this solution at 70 °C for 7 hours. After repeated rinsing with deionized water, a carbon-based material with redox activity was obtained.

[0067] 200mg of V3O7 / V6O 13 The powder, 3 mL of deionized water, and 3 mL of ethanol were placed in a glass bottle and sonicated for 4 hours. Then, 30 mg of redox-active carbon-based material was added, and the mixture was sonicated again for 60 minutes. The glass bottle was then placed in a 60°C water bath and stirred for 24 hours. The product was then frozen in liquid nitrogen for 30 minutes and then dried in a freeze dryer for 72 hours to obtain redox-active carbon-based material coated V3O7 / V6O. 13 The positive electrode material.

[0068] V3O7 / V6O were coated with redox activated carbon-based materials. 13 A positive electrode is prepared using acetylene black as the active material, PVDF as the binder, and NMP as the solvent. Then, the positive electrode, zinc trifluoromethanesulfonate electrolyte, glass fiber separator, zinc negative electrode, spring sheet, and gasket are assembled into a button cell.

[0069] Example 4:

[0070] A hydrogel-like film was prepared by coating a viscous aqueous solution of hard carbon, NaCl, urea, and (NH4)2CO3 onto a glass slide in a mass ratio of 9:31:30:30. The film was then immersed in acetone to extract water. After air drying, the composite film was pressed between two glass slides and transferred to a high-pressure reactor lined with polytetrafluoroethylene and containing a diluted ammonia solution. The reactor was reacted at 190°C for 2.5 hours. After cooling, the film was cleaned with deionized water to obtain nitrogen-doped carbon-based material.

[0071] 1,5-Naphthyldiamine was dissolved in a 0.05 mol / L deionized water solution at 70 °C. Nitrogen-doped carbon-based materials were then immersed in this solution at 70 °C for 7 hours. Afterward, the materials were repeatedly rinsed with deionized water to obtain a carbon-based material with redox activity.

[0072] 100 mg of V₂O₅ powder, 1 mL of deionized water, and 1 mL of ethanol were placed in a glass bottle and sonicated for 2 hours. Then, 20 mg of redox-active carbon-based material was added, and the mixture was sonicated again for 30 minutes. The glass bottle was then placed in a 50°C water bath and stirred for 12 hours. The product was then frozen in liquid nitrogen for 10 minutes and then dried in a freeze dryer for 48 hours to obtain a redox-active carbon-based material coated with V₂O₅ as a cathode material.

[0073] A positive electrode was prepared by coating V2O5 with a product redox activated carbon-based material as the active material, carbon fiber as the conductive agent, PVDF as the binder, and NMP as the solvent. Then, the positive electrode, zinc sulfate electrolyte, glass fiber separator, zinc negative electrode, spring sheet, and gasket were assembled into a button cell.

[0074] Example 5:

[0075] A hydrogel-like film was prepared by coating a viscous aqueous solution of graphite, NaCl, urea, and (NH4)2CO3 onto a glass slide in a mass ratio of 11:30:29:30. The film was then immersed in acetone to extract water. After air drying, the composite film was pressed between two glass slides and transferred to a high-pressure reactor lined with polytetrafluoroethylene and containing a diluted ammonia solution. The reactor was reacted at 170°C for 3 hours. After cooling, the film was cleaned with deionized water to obtain nitrogen-doped carbon-based material.

[0076] 2-Aminophenol was dissolved in a 0.05 mol / L deionized water solution at 70°C. Nitrogen-doped carbon-based material was then immersed in the solution at 70°C for 7 hours. Afterward, it was repeatedly rinsed with deionized water to obtain a carbon-based material with redox activity.

[0077] 200 mg of V₂O₅ powder, 3 mL of deionized water, and 3 mL of ethanol were placed in a glass bottle and sonicated for 4 hours. Then, 30 mg of redox-active carbon-based material was added, and the mixture was sonicated again for 60 minutes. The glass bottle was then placed in a 60°C water bath and stirred for 24 hours. The product was then frozen in liquid nitrogen for 30 minutes and then dried in a freeze dryer for 72 hours to obtain a redox-active carbon-based material coated with V₂O₅ as a cathode material.

[0078] A positive electrode was prepared by coating V2O5 with a product redox activated carbon-based material as the active material, carbon nanotubes as the conductive agent, PVDF as the binder, and NMP as the solvent. Then, the positive electrode, zinc trifluoromethanesulfonate electrolyte, glass fiber membrane, zinc negative electrode, spring sheet, and gasket were assembled into a button cell.

[0079] Comparative Example 1:

[0080] 100mg of V3O7 / V6O 13 The powder, 1 mL of deionized water, and 1 mL of ethanol were placed in a glass bottle and sonicated for 2 hours. The bottle was then placed in a 50°C water bath and stirred for 12 hours. The product was frozen in liquid nitrogen for 10 minutes and then dried in a freeze dryer for 48 hours to obtain V3O7 / V6O. 13 The positive electrode material.

[0081] The product V3O7 / V6O 13 A positive electrode is prepared using SuperP as the active material, PVDF as the conductive agent, and NMP as the binder. Then, the positive electrode, zinc sulfate electrolyte, glass fiber separator, zinc negative electrode, spring sheet, and gasket are assembled into a button cell.

[0082] Comparative Example 2:

[0083] 100 mg of V₂O₅ powder, 1 mL of deionized water, and 1 mL of ethanol were placed in a glass bottle and sonicated for 2 hours, followed by sonication for another 30 minutes. The bottle was then placed in a 50°C water bath and stirred for 12 hours. The product was then frozen in liquid nitrogen for 10 minutes and dried in a freeze dryer for 48 hours to obtain the V₂O₅ cathode material.

[0084] A positive electrode was prepared using V2O5 as the active material, carbon fiber as the conductive agent, PVDF as the binder, and NMP as the solvent. Then, the positive electrode, zinc sulfate electrolyte, glass fiber separator, zinc negative electrode, spring sheet, and gasket were assembled into a button cell.

[0085] Comparative Example 3:

[0086] A hydrogel-like film was prepared by coating a viscous aqueous solution of graphene, NaCl, urea, and (NH4)2CO3 onto a glass slide in a mass ratio of 10:30:30:30. The film was then immersed in acetone to extract water. After air drying, the composite film was pressed between two glass slides and transferred to a high-pressure reactor lined with polytetrafluoroethylene and containing a diluted ammonia solution. The reactor was reacted at 180°C for 3 hours. After cooling, the film was cleaned with deionized water to obtain nitrogen-doped carbon-based material.

[0087] 100mg of V3O7 / V6O 13 The powder, 1 mL of deionized water, and 1 mL of ethanol were placed in a glass bottle and sonicated for 2 hours. Then, 15 mg of nitrogen-doped carbon-based material was added, and the mixture was sonicated again for 30 minutes. The glass bottle was then placed in a 50°C water bath and stirred for 12 hours. The product was then frozen in liquid nitrogen for 10 minutes and then dried in a freeze dryer for 48 hours to obtain nitrogen-doped carbon-based material coated V3O7 / V6O. 13 The positive electrode material.

[0088] V3O7 / V6O is coated with nitrogen-doped carbon-based materials. 13 A positive electrode is prepared using SuperP as the active material, PVDF as the conductive agent, and NMP as the binder. Then, the positive electrode, zinc sulfate electrolyte, glass fiber separator, zinc negative electrode, spring sheet, and gasket are assembled into a button cell.

[0089] Comparative Example 4:

[0090] 4-Aminophenol was dissolved in a 0.06 mol / L deionized water solution at 60°C. Graphene was then immersed in the solution and soaked at 60°C for 6 hours. Afterward, the solution was repeatedly rinsed with deionized water to obtain redox-active graphene.

[0091] 100mg of V3O7 / V6O 13 The powder, 1 mL of deionized water, and 1 mL of ethanol were placed in a glass bottle and sonicated for 2 hours. Then, 15 mg of redox-active graphene was added, and the mixture was sonicated again for 30 minutes. The glass bottle was then placed in a 50°C water bath and stirred for 12 hours. The product was then frozen in liquid nitrogen for 10 minutes and then dried in a freeze dryer for 48 hours to obtain redox-active graphene-coated V3O7 / V6O 13 The positive electrode material.

[0092] V3O7 / V6O were coated with redox-active graphene. 13 A positive electrode is prepared using SuperP as the active material, PVDF as the conductive agent, and NMP as the binder. Then, the positive electrode, zinc sulfate electrolyte, glass fiber separator, zinc negative electrode, spring sheet, and gasket are assembled into a button cell.

[0093] Results analysis:

[0094] The button batteries obtained in Examples 1-5 and Comparative Examples 1-4 were subjected to a 0.1Ag test. -1 ~10Ag -1 Rate performance at 1Ag and -1 The capacity retention rate after 1000 cycles is shown in Table 1.

[0095] Table 1

[0096]

[0097]

[0098] The results show that the vanadium-based cathode material of the present invention has significantly improved cycle stability and capacity. In Comparative Examples 1 and 2, the vanadium-based cathode material was not coated with carbon-based material, and at 10 Ag... -1 Capacity below 100 mAh g at current density -1 1A g -1 At the current density, the capacity retention rate after 1000 cycles is only about 75%. In Comparative Example 3, the vanadium-based cathode material is coated with nitrogen-doped carbon-based material, and in Comparative Example 4, the vanadium-based cathode material is coated with carbon-based material modified with redox active sites (without nitrogen doping). Both showed improved rate performance and capacity retention rate at 10 Ag. -1 Capacity at current density: 130 mAh g -1 Left and right, 1Ag -1 At the specified flow density, the capacity retention rate is approximately 85% after 1000 cycles.

[0099] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a zinc-ion battery cathode material, characterized in that, Includes the following steps, S1: A hydrogel-like film is formed by coating an aqueous solution of carbon-based material, NaCl, urea, and (NH4)2CO3. After dehydration and drying, the film is heated to react and obtain nitrogen-doped carbon-based material. The carbon-based material is selected from one or more of soft carbon, hard carbon, graphite, graphene, and graphene oxide. The mass ratio of carbon-based material, NaCl, urea, and (NH4)2CO3 is 7~13:28~33:28~33:28~33. The heating temperature is 160~200℃ and the time is 2~4h. S2: The nitrogen-doped carbon-based material is immersed in an aqueous solution containing aromatic compounds, wherein the aromatic compounds are oxidatively active, to obtain a carbon-based material with redox activity; the oxidatively active aromatic compounds are selected from one or more of phenylenediamine and its isomers, naphthalenediamine and its isomers, and aminophenol and its isomers. S3: The carbon-based material with redox activity is dispersed in a vanadium-based oxide solution, stirred and reacted, and then freeze-dried to obtain the zinc-ion battery cathode material.

2. The preparation method according to claim 1, characterized in that, In step S2, the concentration of aromatics in the aqueous solution is 0.05~0.07 mol / L; the volume of the aqueous solution containing aromatics required for soaking 50~100 mg of carbon-based material is 100~200 mL.

3. The preparation method according to claim 1, characterized in that, In step S2, the soaking time is 5-8 hours and the temperature is 60-80℃.

4. The preparation method according to claim 1, characterized in that, In step S3, the mass ratio of the redox-active carbon-based material to the vanadium-based oxide is 3~6:20~40.

5. A zinc-ion battery cathode material prepared by any one of claims 1-4.

6. A zinc-ion battery, comprising a positive electrode, characterized in that, The positive electrode material layer of the positive electrode sheet comprises the zinc-ion battery positive electrode material as described in claim 5.

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