A porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material and its preparation method and application

Abstract

The invention belongs to the technical field of batteries and discloses a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material and a preparation method and application thereof. The invention comprises the following steps: adding a pre-prepared uniform solution containing ammonium metavanadate, dihydrated oxalic acid, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion to deionized water, performing ultrasonic treatment to obtain a spinning solution; performing electrostatic spinning on the spinning solution to obtain composite fibers; drying the composite fibers to obtain dried composite fibers; and heat-treating the dried composite fibers to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material having a beaded structure, that is, obtaining a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material. The battery positive electrode material prepared by the invention has good flexibility, high cycle stability and electronic conductivity, and can effectively avoid volume expansion of the electrode material.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and in particular relates to a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material, a preparation method thereof, and applications thereof. Background Art

[0002] With the increasing global demand for clean energy and the replacement of traditional fossil fuels, aqueous zinc-ion batteries (AZBs) are becoming a focus of research and development due to their unique advantages. Zinc is a widely available and low-cost metal, and the manufacturing cost of its batteries is much lower than that of traditional lithium-ion batteries, making its application in energy storage systems more economically viable. Furthermore, metallic zinc has excellent corrosion resistance, ductility, and fluidity, and AAZBs also possess these excellent properties. Compared with traditional lithium-ion batteries, AAZBs are safer and less prone to violent chemical reactions that can lead to thermal runaway or even spontaneous combustion. Furthermore, AAZBs use aqueous or water-based electrolytes, which significantly reduce the risk of fire and explosion compared to organic solvents, making them more reliable and safer in large-scale energy storage systems, especially suitable for grid support and distributed energy systems. Despite the high specific capacity of zinc metal anodes, the energy density of AAZBs remains far lower than that of lithium-ion batteries due to limitations in the cathode materials, limiting their application prospects in high-energy-density applications.

[0003] Currently, existing aqueous zinc-ion battery cathode materials generally suffer from low cycle stability, low electronic conductivity, and volume expansion. The low cycle stability is manifested by the fact that compared with traditional lithium-ion batteries, aqueous zinc-ion battery cathode materials have a shorter cycle life and poorer stability. The low electronic conductivity is manifested by the fact that the electronic conductivity of aqueous zinc-ion battery cathode materials is generally lower than that of lithium-ion battery materials, which in turn affects their charge and discharge speed and overall battery performance. The volume expansion phenomenon is manifested by the fact that during the charge and discharge process, the insertion and extraction of zinc ions in the electrode material causes the electrode volume to expand, thus affecting battery performance and life. Therefore, there is an urgent need for a new rechargeable zinc-ion battery cathode material with a long cycle life, good stability, high electronic conductivity, and significant application scenarios in the new energy field. Summary of the Invention

[0004] In response to the technical problems existing in the prior art, the present invention provides a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material and its preparation method and application, so as to solve the technical problems of low cycle stability, low electronic conductivity and volume expansion phenomenon commonly existing in the existing aqueous zinc ion battery positive electrode materials.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The present invention provides a method for preparing a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material, which is characterized by comprising:

[0007] A pre-prepared homogeneous solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion is added to deionized water and ultrasonically treated to obtain a spinning solution;

[0008] electrospinning the spinning solution to obtain composite fibers;

[0009] The composite fibers are dried to obtain dried composite fibers; the dried composite fibers are heat-treated to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure, that is, a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material is obtained.

[0010] Furthermore, the mass ratio of the uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion to deionized water is (0.4-0.9):1.

[0011] Furthermore, in the homogeneous solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion, the mass ratio of ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion is 1:2:1:(1-6).

[0012] Furthermore, the preparation process of the uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion is as follows:

[0013] PVP was added to deionized water and stirred vigorously until uniform to obtain a PVP solution;

[0014] ammonium metavanadate, oxalic acid and PVP solution are mixed and reacted to obtain a precursor solution;

[0015] The precursor solution is ultrasonically treated in an ice-water bath. After the ultrasonic treatment is completed, polytetrafluoroethylene emulsion is added to obtain a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion.

[0016] Furthermore, during the electrospinning process of the spinning solution to obtain the composite fiber, the voltage was 12-35 kV, the ambient humidity was controlled at 40%-60%, the distance between the metal needle and the collector was 10-20 cm, and the temperature was controlled at 20-50°C.

[0017] Furthermore, in the process of electrostatically spinning the spinning solution to obtain the composite fiber, a non-woven fabric is used as a receiving member for the composite fiber.

[0018] Furthermore, the composite fiber is dried to obtain the dried composite fiber at a drying temperature of 60-80° C. and a drying time of 2-4 hours.

[0019] Furthermore, the process of heat treating the dried composite fiber is as follows:

[0020] The dried composite fiber is kept at 150-250°C for 2-4 hours at a heating rate of 2-10°C / min; then the temperature is continued to be raised at 250-350°C for 2-4 hours at a heating rate of 2-10°C / min to obtain a flexible self-supporting composite nanofiber;

[0021] Then, under a protective atmosphere, the flexible self-supporting composite nanofiber is kept at 650-750° C. for 4-6 hours at a heating rate of 2-10° C. / min to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure.

[0022] The present invention also provides a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material, which is prepared using the method for preparing the porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material.

[0023] The present invention also provides an application of a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material. The porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material is used in an aqueous zinc ion battery and serves as the positive electrode of the aqueous zinc ion battery.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention provides a method for preparing a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material, which comprises the following steps: mixing a uniform solution containing ammonium metavanadate, dihydrated oxalic acid, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion with deionized water to prepare a spinning solution, preparing composite fibers using an electrostatic spinning process, and drying and heat-treating the composite fibers to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure; wherein, water is used as a solvent for electrostatic spinning, which can reduce pollution during the spinning process and has the advantages of being safe and green; PVP is used as a flexible substrate support for a carbon source, and the PVP is carbonized through a heat treatment process. The carbonized PVP serves as a reinforcing agent and a conductive material to improve the electrode stability; and a precursor salt is used to generate an active substance in situ in the carbon skeleton, giving the carbon fiber a high-efficiency Secondly, the beaded structure can effectively increase the contact area between the electrode material and the electrolyte, greatly improve the insertion and extraction of ions, avoid structural collapse or destruction during the electrochemical reaction, reduce impedance and reduce energy consumption, and thus effectively improve the conductivity and energy storage of the material; the porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material prepared by the present invention has good flexibility, high cycle stability and electronic conductivity, and can effectively avoid the volume expansion phenomenon of the electrode material; the preparation process is simple, safe and environmentally friendly, and easy to prepare on a large scale; the prepared porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material can be used in aqueous zinc ion batteries as a positive electrode, and can also be used in other ion batteries, lithium-sulfur batteries and other electrochemical and energy storage fields, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 This is a SEM image of the vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure prepared in Example 6 with an accuracy of 1000 nm;

[0028] Figure 2 This is a SEM image of the vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure prepared in Example 6 with an accuracy of 100 nm;

[0029] Figure 3 This is a charge-discharge curve of the vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure prepared in Example 6 at a current density of 0.1 A / g;

[0030] Figure 4 This is a graph showing the rate performance of the vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure prepared in Example 6 at different current densities;

[0031] Figure 5 This is a long cycle performance diagram of the vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure prepared in Example 6 at a current density of 10A / g. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions, and beneficial effects solved by this application more clearly understood, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application; it is obvious that the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of this application.

[0033] The present invention provides a method for preparing a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material, comprising the following steps:

[0034] Step 1: Add polyvinylpyrrolidone (PVP) to deionized water, stir vigorously at 50-65°C for 8-16 hours, until the mixture is evenly stirred to obtain a uniform and stable mixed system, thereby obtaining a PVP solution.

[0035] Step 2: Mix ammonium metavanadate (NH4VO3), oxalic acid (H2C2O4) and PVP solution and react until the solution changes from orange to blue to obtain a precursor solution.

[0036] Step 3. Ultrasonicate the precursor solution in an ice-water bath for 1-2 hours. After the ultrasonication is completed, add polytetrafluoroethylene emulsion (PTFE) to obtain a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion; wherein the mass ratio of ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion in the uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion is 1:2:1:(1-6).

[0037] Step 4: Mix a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion with deionized water in a mass ratio of (0.4-0.9):1, and perform ultrasonic treatment to obtain a spinning solution.

[0038] Step 5: Using an electrospinning process, using a non-woven fabric as a receiving member for the composite fiber, the spinning solution is electrospun to obtain the composite fiber; wherein, during the electrospinning process, the voltage is 12-35 kV, the ambient humidity is controlled at 40%-60%, and the temperature is controlled at 20-50°C; the speed of the collector is controlled at 500-1000 r / min; a No. 21 metal needle is used, the distance between the metal needle and the collector is 10-20 cm, and the liquid pushing speed is 10-30 μL / min.

[0039] Step 6, drying the composite fiber at 60-80° C. for 2-4 hours to obtain a dried composite fiber;

[0040] Step 7: heat-treating the dried composite fiber to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure, that is, obtaining a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material.

[0041] The heat treatment process is specifically as follows:

[0042] The dried composite fiber is kept at 150-250°C for 2-4 hours at a heating rate of 2-10°C / min; then the temperature is continued to be raised at 250-350°C for 2-4 hours at a heating rate of 2-10°C / min to obtain a flexible self-supporting composite nanofiber;

[0043] Then, under a protective atmosphere, the flexible self-supporting composite nanofiber is kept at 650-750° C. for 4-6 hours at a heating rate of 2-10° C. / min to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure.

[0044] Preparation principle:

[0045] The method for preparing the porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material described in the present invention first prepares a solution containing a trivalent vanadium source, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion and uses it as a spinning solution; then uses electrospinning technology to prepare the spinning solution into composite nanofibers based on a vanadium precursor; then pre-oxidizes the spun composite nanofibers to remove residual solvent, and further heat-treats the composite nanofibers to obtain composite nanofibers with a beaded structure grown through in-situ reaction generation and phase separation; after heat treatment in an argon atmosphere, the original polymer nanofibers are carbonized into carbon nanofibers; due to the increase in the proportion of graphite carbon, the conductivity of the carbon nanofibers is greatly improved, and they have excellent mechanical strength, which is sufficient to be used as a single electrode in electrochemical research and energy storage.

[0046] In the present invention, the prepared flexible zinc ion battery positive electrode has a special beaded microstructure, which is conducive to the full contact between the electrode material and the electrolyte. At the same time, the microscopic dispersion of the active substance of the electrode material is also improved, which is of great help to the performance improvement of the overall electrochemical energy storage device. It is worth mentioning that the microstructure of the beaded carbon fiber can greatly improve the embedding and extraction of ions, and can avoid structural collapse or destruction during the electrochemical reaction process. The vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode with a beaded structure of the present invention can also be used in other electrochemical and energy storage fields such as ion batteries and lithium-sulfur batteries. In addition, the preparation process of the present invention is simple, safe and environmentally friendly, easy to prepare on a large scale, and has broad application prospects.

[0047] Example 1

[0048] This embodiment 1 provides a method for preparing a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material, comprising the following steps:

[0049] Step 1: Add polyvinylpyrrolidone (PVP) to deionized water and stir vigorously at 50° C. for 8 h until the mixture is evenly stirred to obtain a uniform and stable mixed system to obtain a PVP solution.

[0050] Step 2: Mix ammonium metavanadate (NH4VO3), oxalic acid (H2C2O4) and PVP solution and react until the solution changes from orange to blue to obtain a precursor solution.

[0051] Step 3. Ultrasonicate the precursor solution in an ice-water bath for 1 hour. After the ultrasonication is completed, add polytetrafluoroethylene emulsion (PTFE) to obtain a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion; wherein the mass ratio of ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion in the uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion is 1:2:1:1.

[0052] Step 4: Mix a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion with deionized water in a mass ratio of 0.4:1, and perform ultrasonic treatment to obtain a spinning solution.

[0053] Step 5: Using an electrospinning process, using non-woven fabric as a receiving member for the composite fiber, the spinning solution is electrospun to obtain the composite fiber; wherein, during the electrospinning process, the voltage is 12 kV, the ambient humidity is controlled at 40%, and the temperature is controlled at 20°C; the speed of the collector is controlled at 500 r / min; a No. 21 metal needle is used, the distance between the metal needle and the collector is 10 cm, and the liquid pushing speed is 10 μL / min.

[0054] Step 6: Dry the composite fiber at 60° C. for 2 hours to obtain a dried composite fiber.

[0055] Step 7: heat-treating the dried composite fiber to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure, that is, obtaining a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material.

[0056] The heat treatment process is specifically as follows:

[0057] The dried composite fibers were kept at 150°C for 2 hours at a heating rate of 2°C / min; then the temperature was continued to rise at 2°C / min and kept at 250°C for 2 hours to obtain flexible self-supporting composite nanofibers.

[0058] Then, under a protective atmosphere, the flexible self-supporting composite nanofibers were kept at 650°C for 4 hours at a heating rate of 2°C / min to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure.

[0059] Performance testing:

[0060] The porous vanadium-based composite carbon nanofiber flexible zinc-ion battery positive electrode material prepared in this Example 1 was experimentally tested, and the test results showed that the beaded structure porous vanadium-based composite carbon nanofiber flexible zinc-ion battery positive electrode material prepared by electrospinning has good cycle performance and high conductivity, and can effectively reduce volume expansion, thereby improving electrochemical performance.

[0061] Example 2

[0062] This embodiment 2 provides a method for preparing a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material, comprising the following steps:

[0063] Step 1: Add polyvinylpyrrolidone (PVP) to deionized water and vigorously stir at 52° C. for 10 h until the mixture is uniformly stirred to obtain a homogeneous and stable mixed system to obtain a PVP solution.

[0064] Step 2: Mix ammonium metavanadate (NH4VO3), oxalic acid (H2C2O4) and PVP solution and react until the solution changes from orange to blue to obtain a precursor solution.

[0065] Step 3. Ultrasonicate the precursor solution in an ice-water bath for 1.2 hours. After the ultrasonication is completed, add polytetrafluoroethylene emulsion (PTFE) to obtain a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion; wherein the mass ratio of ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion in the uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion is 1:2:1:2.

[0066] Step 4: Mix a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion with deionized water in a mass ratio of 0.5:1, and perform ultrasonic treatment to obtain a spinning solution.

[0067] Step 5: Using an electrospinning process, a non-woven fabric is used as a receiving member for the composite fiber, and the spinning solution is electrospun to obtain the composite fiber; wherein, during the electrospinning process, the voltage is 16 kV, the ambient humidity is controlled at 40%, and the temperature is controlled at 25°C; the speed of the collector is controlled at 600 r / min; a No. 21 metal needle is used, the distance between the metal needle and the collector is 12 cm, and the liquid pushing speed is 15 μL / min.

[0068] Step 6: Dry the composite fiber at 65° C. for 2.5 hours to obtain a dried composite fiber.

[0069] Step 7: heat-treating the dried composite fiber to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure, that is, obtaining a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material.

[0070] The heat treatment process is specifically as follows:

[0071] The dried composite fibers were kept at 170°C for 2.5 hours at a heating rate of 4°C / min. The fibers were then kept at 270°C for 2.5 hours at a heating rate of 4°C / min to obtain flexible self-supporting composite nanofibers.

[0072] Then, under a protective atmosphere, the flexible self-supporting composite nanofibers were kept at 670°C for 4.5 hours at a heating rate of 4°C / min to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure.

[0073] Performance testing:

[0074] The porous vanadium-based composite carbon nanofiber flexible zinc-ion battery positive electrode material prepared in Example 2 was experimentally tested. The test results showed that the beaded structure porous vanadium-based composite carbon nanofiber flexible zinc-ion battery positive electrode material prepared by electrospinning has good cycle performance and high conductivity, and can effectively reduce volume expansion, thereby improving electrochemical performance.

[0075] Example 3

[0076] This embodiment 3 provides a method for preparing a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material, comprising the following steps:

[0077] Step 1: Add polyvinylpyrrolidone (PVP) to deionized water and vigorously stir at 56° C. for 12 h until the mixture is uniformly stirred to obtain a homogeneous and stable mixed system to obtain a PVP solution.

[0078] Step 2: Mix ammonium metavanadate (NH4VO3), oxalic acid (H2C2O4) and PVP solution and react until the solution changes from orange to blue to obtain a precursor solution.

[0079] Step 3. Ultrasonicate the precursor solution in an ice-water bath for 1.4 hours. After the ultrasonication is completed, add polytetrafluoroethylene emulsion (PTFE) to obtain a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion; wherein the mass ratio of ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion in the uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion is 1:2:1:3.

[0080] Step 4: Mix a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion with deionized water in a mass ratio of 0.6:1, and perform ultrasonic treatment to obtain a spinning solution.

[0081] Step 5: Using an electrospinning process, a non-woven fabric is used as a receiving member for the composite fiber, and the spinning solution is electrospun to obtain the composite fiber; wherein, during the electrospinning process, the voltage is 18 kV, the ambient humidity is controlled at 50%, and the temperature is controlled at 30°C; the speed of the collector is controlled at 700 r / min; a No. 21 metal needle is used, the distance between the metal needle and the collector is 14 cm, and the liquid pushing speed is 20 μL / min.

[0082] Step 6: drying the composite fiber at 70° C. for 3 hours to obtain a dried composite fiber;

[0083] Step 7: heat-treating the dried composite fiber to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure, that is, obtaining a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material.

[0084] The heat treatment process is specifically as follows:

[0085] The dried composite fibers were kept at 200°C for 3 hours at a heating rate of 6°C / min; then the temperature was continued to rise at 300°C for 3 hours at a heating rate of 6°C / min to obtain flexible self-supporting composite nanofibers.

[0086] Then, under a protective atmosphere, the flexible self-supporting composite nanofibers were kept at 690°C for 5 hours at a heating rate of 6°C / min to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure.

[0087] Performance testing:

[0088] The porous vanadium-based composite carbon nanofiber flexible zinc-ion battery positive electrode material prepared in Example 3 was experimentally tested. The test results showed that the beaded structure porous vanadium-based composite carbon nanofiber flexible zinc-ion battery positive electrode material prepared by electrospinning has good cycle performance and high conductivity, and can effectively reduce volume expansion, thereby improving electrochemical performance.

[0089] Example 4

[0090] This embodiment 4 provides a method for preparing a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material, comprising the following steps:

[0091] Step 1: Add polyvinylpyrrolidone (PVP) to deionized water and vigorously stir at 58° C. for 14 hours until the mixture is evenly stirred to obtain a uniform and stable mixed system to obtain a PVP solution.

[0092] Step 2: Mix ammonium metavanadate (NH4VO3), oxalic acid (H2C2O4) and PVP solution and react until the solution changes from orange to blue to obtain a precursor solution.

[0093] Step 3. Ultrasonicate the precursor solution in an ice-water bath for 1.6 hours. After the ultrasonication is completed, add polytetrafluoroethylene emulsion (PTFE) to obtain a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion; wherein the mass ratio of ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion in the uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion is 1:2:1:4.

[0094] Step 4: Mix a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion with deionized water in a mass ratio of 0.7:1, and perform ultrasonic treatment to obtain a spinning solution.

[0095] Step 5: Using an electrospinning process, using a non-woven fabric as a receiving member for the composite fiber, the spinning solution is electrospun to obtain the composite fiber; wherein, during the electrospinning process, the voltage is 24 kV, the ambient humidity is controlled at 55%, and the temperature is controlled at 35°C; the speed of the collector is controlled at 800 r / min; a No. 21 metal needle is used, the distance between the metal needle and the collector is 16 cm, and the liquid pushing speed is 25 μL / min.

[0096] Step 6, drying the composite fiber at 70° C. for 3.5 hours to obtain a dried composite fiber;

[0097] Step 7: heat-treating the dried composite fiber to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure, that is, obtaining a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material.

[0098] The heat treatment process is specifically as follows:

[0099] The dried composite fibers were kept at 210°C for 3 hours at a heating rate of 8°C / min; then the temperature was continued to rise at 8°C / min and kept at 310°C for 3 hours to obtain flexible self-supporting composite nanofibers.

[0100] Then, under a protective atmosphere, the flexible self-supporting composite nanofibers were kept at 710°C for 5.5 hours at a heating rate of 8°C / min to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure.

[0101] Performance testing:

[0102] The porous vanadium-based composite carbon nanofiber flexible zinc-ion battery positive electrode material prepared in this Example 4 was experimentally tested. The test results showed that the beaded structure porous vanadium-based composite carbon nanofiber flexible zinc-ion battery positive electrode material prepared by electrospinning has good cycle performance and high conductivity, and can effectively reduce volume expansion, thereby improving electrochemical performance.

[0103] Example 5

[0104] This embodiment 5 provides a method for preparing a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material, comprising the following steps:

[0105] Step 1: Add polyvinylpyrrolidone (PVP) to deionized water and vigorously stir at 62° C. for 15 h until the mixture is evenly stirred to obtain a uniform and stable mixed system to obtain a PVP solution.

[0106] Step 2: Mix ammonium metavanadate (NH4VO3), oxalic acid (H2C2O4) and PVP solution and react until the solution changes from orange to blue to obtain a precursor solution.

[0107] Step 3. Ultrasonicate the precursor solution in an ice-water bath for 1.8 hours. After the ultrasonication is completed, add polytetrafluoroethylene emulsion (PTFE) to obtain a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion; wherein the mass ratio of ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion in the uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion is 1:2:1:5.

[0108] Step 4: Mix a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion with deionized water in a mass ratio of 0.8:1, and perform ultrasonic treatment to obtain a spinning solution.

[0109] Step 5: Using an electrospinning process, using a non-woven fabric as a receiving member for the composite fiber, the spinning solution is electrospun to obtain the composite fiber; wherein, during the electrospinning process, the voltage is 28 kV, the ambient humidity is controlled at 55%, and the temperature is controlled at 45°C; the speed of the collector is controlled at 900 r / min; a No. 21 metal needle is used, the distance between the metal needle and the collector is 18 cm, and the liquid pushing speed is 25 μL / min.

[0110] Step 6: drying the composite fiber at 75° C. for 3.5 hours to obtain a dried composite fiber;

[0111] Step 7: heat-treating the dried composite fiber to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure, that is, obtaining a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material.

[0112] The heat treatment process is specifically as follows:

[0113] The dried composite fibers were kept at 230°C for 3.5 hours at a heating rate of 8°C / min; then the temperature was continued to rise at 330°C for 5.5 hours at a heating rate of 8°C / min to obtain flexible self-supporting composite nanofibers.

[0114] Then, under a protective atmosphere, the flexible self-supporting composite nanofibers were kept at 730°C for 6 hours at a heating rate of 8°C / min to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure.

[0115] Performance testing:

[0116] The porous vanadium-based composite carbon nanofiber flexible zinc-ion battery positive electrode material prepared in this Example 5 was experimentally tested, and the test results showed that the beaded structure porous vanadium-based composite carbon nanofiber flexible zinc-ion battery positive electrode material prepared by electrospinning has good cycle performance and high conductivity, and can effectively reduce volume expansion, thereby improving electrochemical performance.

[0117] Example 6

[0118] This Example 6 provides a method for preparing a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material, comprising the following steps:

[0119] Step 1: Add polyvinylpyrrolidone (PVP) to deionized water and vigorously stir at 65° C. for 16 hours until the mixture is evenly stirred to obtain a uniform and stable mixed system to obtain a PVP solution.

[0120] Step 2: Mix ammonium metavanadate (NH4VO3), oxalic acid (H2C2O4) and PVP solution and react until the solution changes from orange to blue to obtain a precursor solution.

[0121] Step 3. Ultrasonicate the precursor solution in an ice-water bath for 2 hours. After the ultrasonication is completed, add polytetrafluoroethylene emulsion (PTFE) to obtain a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion; wherein the mass ratio of ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion in the uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion is 1:2:1:6.

[0122] Step 4: Mix a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion with deionized water in a mass ratio of 0.9:1, and perform ultrasonic treatment to obtain a spinning solution.

[0123] Step 5: Using an electrospinning process, using a non-woven fabric as a receiving member for the composite fiber, the spinning solution is electrospun to obtain the composite fiber; wherein, during the electrospinning process, the voltage is 35 kV, the ambient humidity is controlled at 50%, and the temperature is controlled at 50°C; the speed of the collector is controlled at 1000 r / min; a No. 21 metal needle is used, the distance between the metal needle and the collector is 20 cm, and the liquid pushing speed is 30 μL / min.

[0124] Step 6, drying the composite fiber at 80° C. for 4 hours to obtain a dried composite fiber;

[0125] Step 7: heat-treating the dried composite fiber to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure, that is, obtaining a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material.

[0126] The heat treatment process is specifically as follows:

[0127] The dried composite fibers were kept at 250°C for 4 hours at a heating rate of 10°C / min; then the temperature was continued to rise at 350°C for 4 hours at a heating rate of 10°C / min to obtain flexible self-supporting composite nanofibers.

[0128] Then, under a protective atmosphere, the flexible self-supporting composite nanofibers were kept at 750°C for 6 hours at a heating rate of 10°C / min to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure.

[0129] Performance testing:

[0130] The porous vanadium-based composite carbon nanofiber flexible zinc-ion battery positive electrode material prepared in Example 6 was experimentally tested, and the test results showed that the beaded structure porous vanadium-based composite carbon nanofiber flexible zinc-ion battery positive electrode material prepared by electrospinning has good cycle performance and high conductivity, and can effectively reduce volume expansion, thereby improving electrochemical performance.

[0131] As attached Figure 1 As shown, attached Figure 1 The SEM image of the vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure prepared in Example 6 with an accuracy of 1000 nm is given in the attached figure. Figure 2 The SEM image of the vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure prepared in Example 6 with an accuracy of 100 nm is given in the attached figure. Figure 1-2 It can be seen that after carbonization, the fiber surface has a bead-like structure, which can further increase the contact between the electrolyte and the electrode.

[0132] As attached Figure 3 As mentioned above, Figure 3 The charge and discharge curves of the vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure prepared in Example 6 at a current density of 0.1a / g are given in the accompanying drawings. Figure 3 It can be seen that at low current density, the prepared electrode material has a higher specific capacity, reaching 390mah / g.

[0133] As attached Figure 4 As mentioned above, Figure 4 The rate performance diagram of the vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure prepared in Example 6 at different current densities is given in the attached figure. Figure 4 It can be seen that at current densities of 0.5A / g, 0.7A / g, 1A / g, 3A / g, 5A / g, 7A / g, 10A / g, 15A / g and 20A / g, the discharge specific capacity of the electrode is 349.5mAh / g, 321.1mAh / g, 302.1mAh / g, 221.7mAh / g, 174.9mAh / g, 151.1mAh / g, 130mAh / g, 105.4mAh / g and 88.3mAh / g, respectively, showing excellent charge and discharge specific capacity and good capacity retention.

[0134] As attached Figure 5 As mentioned above, Figure 5 The long cycle performance diagram of the vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure prepared in Example 6 at a current density of 10a / g is given in the accompanying Figure 5 It can be seen that the capacity hardly decreases with the increase of the number of cycles, indicating that the electrode has good cycle stability. The reason is that the beaded structure of the electrode keeps the capacity unchanged when zinc ions are embedded and extracted during the charge and discharge process. On the one hand, the carbon skeleton provides an expandable volume, and on the other hand, it improves the cycle stability of the material.

[0135] The method for preparing the porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material described in the present invention adopts an electrospinning process to prepare the material, using water as a solvent for electrospinning, which is safe and green. PVP is used as a flexible substrate support for the carbon source, and then the PVP is carbonized using a high-temperature carbonization process. The carbonized PVP can be used as a reinforcing agent and conductive material to improve the stability of the electrode. The precursor salt is also generated in situ in the carbon skeleton to generate active substances, giving the carbon fiber skeleton an efficient conductive network. At the same time, the beaded structure also greatly improves its conductivity and energy storage. A flexible, conductive, lightweight zinc ion battery positive electrode material with high rate and excellent cycle performance is prepared.

[0136] The porous vanadium-based composite carbon nanofiber flexible zinc-ion battery positive electrode material prepared in the present invention has a beaded structure vanadium-based composite carbon nanofiber flexible electrode material with a special microstructure. This microstructure can increase the contact area between the electrode material and the electrolyte, reduce impedance, and reduce energy consumption; the electrode material has a unique carbon skeleton support, which improves the electrochemical stability of the positive electrode material; water is used as the spinning solvent in the preparation process, which can reduce pollution during the spinning process and conforms to the concept of green chemistry; the beaded V2O3@CNFs electrode material prepared by electrospinning has good flexibility and high zinc ion storage performance.

[0137] The above embodiment is only one of the implementation methods that can realize the technical solution of the present invention. The scope of protection claimed by the present invention is not limited only to this embodiment, but also includes changes, replacements and other implementation methods that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention.

Claims

1. A method for preparing a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material, characterized in that: include: A pre-prepared homogeneous solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion is added to deionized water and ultrasonically treated to obtain a spinning solution; electrospinning the spinning solution to obtain composite fibers; drying the composite fiber to obtain a dried composite fiber; The dried composite fibers are heat-treated to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material having a beaded structure, that is, a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material. The mass ratio of the homogeneous solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion to deionized water is (0.4-0.9):1; The mass ratio of ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion in the homogeneous solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion is 1:2:1:(1-6); The preparation process of the uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion is as follows: PVP was added to deionized water and stirred vigorously until uniform to obtain a PVP solution; ammonium metavanadate, oxalic acid and PVP solution are mixed and reacted to obtain a precursor solution; The precursor solution is ultrasonically treated in an ice-water bath, and after the ultrasonic treatment is completed, polytetrafluoroethylene emulsion is added to obtain a uniform solution containing ammonium metavanadate, oxalic acid dihydrate, polyvinyl pyrrolidone and polytetrafluoroethylene emulsion; The composite fiber is dried to obtain the dried composite fiber at a temperature of 60-80° C. and a drying time of 2-4 hours; The process of heat treatment of the dried composite fiber is as follows: The dried composite fiber is kept at 150-250°C for 2-4 hours at a heating rate of 2-10°C / min; then the temperature is continued to be raised at 250-350°C for 2-4 hours at a heating rate of 2-10°C / min to obtain a flexible self-supporting composite nanofiber; Then, under a protective atmosphere, the flexible self-supporting composite nanofiber is kept at 650-750° C. for 4-6 hours at a heating rate of 2-10° C. / min to obtain a vanadium trioxide-based composite carbon nanofiber flexible electrode material with a beaded structure.

2. The method for preparing a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material according to claim 1, characterized in that: During the electrospinning process of the spinning solution to obtain the composite fiber, the voltage is 12-35 kV, the ambient humidity is controlled at 40%-60%, the distance between the metal needle and the collector is 10-20 cm, and the temperature is controlled at 20-50°C.

3. The method for preparing a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material according to claim 1, characterized in that: In the process of electrostatically spinning the spinning solution to obtain the composite fiber, a non-woven fabric is used as a receiving member for the composite fiber.

4. A porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material, characterized in that: The porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material is prepared using the preparation method of any one of claims 1 to 3.

5. The use of a porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material as claimed in claim 4, characterized in that: The porous vanadium-based composite carbon nanofiber flexible zinc ion battery positive electrode material is used in an aqueous zinc ion battery and serves as the positive electrode of the aqueous zinc ion battery.

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