A porous carbon confined monodisperse copper / carbon fiber composite energy storage material, a preparation method and application thereof

Abstract

The application discloses a kind of porous carbon confined monodisperse copper / carbon fiber composite energy storage materials and preparation method and application thereof.The preparation method includes that bivalent zinc salt solution and dimethyl imidazole solution are mixed uniformly and then stand, Zn-ZIF is prepared;The Zn-ZIF is placed in bivalent copper salt solution, and Zn / Cu-ZIF is prepared by ultrasonic treatment;Zn / Cu-ZIF is dissolved in organic solvent, then high molecular polymer powder is added, and precursor fiber is prepared by electrostatic spinning after stirring and mixing uniformly;The precursor fiber is dried and then heat treated to prepare pre-oxidized precursor fiber, and Cu / PPCs are prepared by vacuum calcination of the pre-oxidized precursor fiber;The Cu / PPCs are washed to prepare porous carbon confined monodisperse copper / carbon fiber composite material.The method is simple to operate, reasonable in design, controllable in cost, low in energy consumption, can significantly improve the specific surface area of carbon cloth, and the product can control the nucleation and deposition of zinc ions, thereby effectively inhibiting the growth of zinc dendrites and improving the cycle life of zinc negative electrode.

Description

Technical Field

[0001] This invention belongs to the field of energy storage materials technology, and relates to a porous carbon-confined monodisperse copper / carbon fiber composite energy storage material, its preparation method and application. Background Technology

[0002] Safety concerns associated with lithium metal, the scarcity of lithium resources, high costs, and toxic organic electrolytes have limited the green and sustainable development of lithium-ion batteries. Aqueous electrolytes, on the other hand, offer advantages such as high thermodynamic stability, non-toxicity, and low cost, improving the safety of aqueous batteries and expanding their application scenarios for rechargeable batteries. However, aqueous zinc-ion batteries still face uncontrollable zinc anode dendrite growth and side reactions (hydrogen evolution, corrosion, and passivation) during operation, significantly restricting their further development.

[0003] Currently, researchers have developed several strategies to slow down or suppress the growth of zinc dendrites in zinc anodes. Carbon materials, with their sufficiently high conductivity, can regulate zinc ion deposition and induce rapid electron / ion deposition, giving them a unique advantage in suppressing zinc dendrite growth. However, pure carbon materials such as graphene and carbon nanotubes suffer from insufficient pore volume and specific surface area, resulting in fewer reactive sites. This leads to uneven zinc deposition or dendrite formation during cycling, affecting the cycle life of zinc-ion batteries. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a porous carbon-confined monodisperse copper / carbon fiber composite energy storage material, its preparation method, and its application. This solves the technical problem in the prior art where insufficient pore volume and specific surface area of ​​carbon materials, coupled with a limited number of reactive sites, lead to uneven zinc deposition or dendrite formation during cycling, thus affecting the cycle life of zinc-ion batteries.

[0005] This invention is achieved through the following technical solution:

[0006] A method for preparing a porous carbon-confined monodisperse copper / carbon fiber composite material includes the following steps:

[0007] S1: Mix zinc salt solution and dimethylimidazole solution evenly, sonicate and let stand to obtain Zn-ZIF;

[0008] S2: The Zn-ZIF is placed in a copper salt solution and ultrasonically treated to obtain Zn / Cu-ZIF;

[0009] S3: Dissolve Zn / Cu-ZIF in an organic solvent, then add polyacrylonitrile powder, stir and mix evenly, and then prepare precursor fibers by electrospinning;

[0010] S4: The precursor fiber is dried and then heat-treated to obtain pre-oxidized precursor fiber. The pre-oxidized precursor fiber is then calcined under vacuum to obtain Cu / PPCs.

[0011] Preferably, in step S1, the zinc salt is one or two of zinc nitrate hexahydrate, anhydrous zinc acetate, or zinc acetate dihydrate; in the mixed solution of zinc salt and dimethylimidazole, the concentration of zinc salt is 0.05-0.25 mol / L, and the concentration of dimethylimidazole is 0.25-0.5 mol / L.

[0012] Preferably, in step S2, the copper salt is copper nitrate and / or copper acetate; the concentration of the copper salt is 0.005 to 0.05 mol / L.

[0013] Preferably, in step S3, the number-average molecular weight of the polyacrylonitrile is 1 million to 2 million.

[0014] Preferably, in step S3, Zn / Cu-ZIF is dissolved in an organic solvent, and then polyacrylonitrile powder is added. After stirring and mixing evenly, the mass concentration of Zn / Cu-ZIF is 0.04-0.12 g / mL, and the mass of the polyacrylonitrile powder is 0.1-0.2 g / mL.

[0015] Preferably, in step S3, during the electrospinning process, the voltage is ~5KV to 15KV, and the distance from the needle to the receiving shaft is 15cm.

[0016] Preferably, in step S4, the heat treatment temperature is 200–300°C and the time is 90–240 min.

[0017] Preferably, in step S4, during the vacuum calcination process, the calcination temperature is 800–1200°C and the calcination time is 2–4 hours.

[0018] A porous carbon-confined monodisperse copper / carbon fiber composite material was prepared by the method described above.

[0019] The above-mentioned porous carbon-confined monodisperse copper / carbon fiber composite material is used in energy storage devices.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] This invention discloses a method for preparing a porous carbon-confined monodisperse copper / carbon fiber composite material. The method first prepares Zn-ZIF by reacting divalent zinc salt with dimethylimidazole, then prepares Zn / Cu-ZIF by reacting Zn-ZIF with divalent copper salt. Zn / Cu-ZIF precursor fibers are prepared via electrospinning. These precursor fibers are then heat-treated to obtain pre-oxidized precursor fibers. The pre-oxidized precursor fibers are then vacuum-calcined to obtain Cu / PPCs. Finally, a washing process yields the porous carbon-confined monodisperse copper / carbon fiber composite material. This invention, by introducing Zn / Cu-ZIF as a porous carbon precursor to modify pure carbon fibers and optimizing the preparation process, effectively improves the pore volume and specific surface area of ​​the material, providing a three-dimensional space to accommodate zinc dendrites. Furthermore, the introduced monodisperse copper serves as a deposition site for zinc ions, effectively addressing the shortcomings of pure carbon materials as anodes in zinc-ion batteries. This method involves adding Zn / Cu-ZIF powder with a specific structure and then performing high-temperature carbonization to obtain porous carbon fibers with large pore volumes. This three-dimensional porous structure can accommodate zinc dendrites grown during the charge-discharge process. Furthermore, the zinc-loving monodisperse copper generated after Zn / Cu-ZIF carbonization attracts zinc ions to preferentially deposit on the porous carbon fibers, further optimizing the high electrical conductivity of the carbon fibers. Simultaneously, the precursor fibers undergo heat treatment during the preparation process to achieve pre-oxidation, which effectively prevents problems such as "melt adhesion" of the fibers, ensuring the microstructural stability and conductivity of the material. This invention selects Zn-MOF with a low boiling point as a template and further loads high-boiling-point active metallic copper particles. During the subsequent high-temperature treatment, the zinc metal volatilizes, forming porous carbon, while the metallic copper particles are retained. Furthermore, this invention employs electrospinning technology to synthesize porous carbon fibers in one step. Adding an appropriate amount of Zn / Cu-ZIF particles during electrospinning allows control over the pore volume of the porous carbon fibers, resulting in metal-ion-doped porous carbon with a high specific surface area. This method is universal; by preparing ZIF / MOF powders with different metal ions, porous carbon fibers doped with different metal particles can be synthesized. The preparation method of this invention is simple to operate, rationally designed, cost-effective, and energy-efficient, significantly improving the specific surface area of ​​carbon cloth. This invention, by designing carbon materials with a three-dimensional structure and abundant pore size, not only alleviates volume expansion and reduces local current density but also regulates zinc ion nucleation and deposition, thereby effectively inhibiting zinc dendrite growth and improving the cycle life of the zinc anode. In addition, the introduction of zinc-loving metals can improve the utilization rate of zinc-loving active sites, effectively reducing the zinc nucleation energy barrier. Furthermore, zinc-loving metals have a strong zinc-binding ability; metallic zinc can improve the uniformity of zinc deposition by forming a stable structure with zinc-loving species, effectively improving the cycle life of zinc-ion batteries.

[0022] Furthermore, in step S1, the zinc salt is one or two of zinc nitrate hexahydrate, anhydrous zinc acetate, or zinc acetate dihydrate; in the mixed solution of zinc salt and dimethylimidazole, the concentration of zinc salt is 0.025-0.05 mol / L, and the concentration of dimethylimidazole is 0.25-0.5 mol / L. This parameter control can enable the effective synthesis of Zn-ZIF.

[0023] Furthermore, in step S2, the copper salt is copper nitrate and / or copper acetate; the concentration of the copper salt is 0.005 to 0.05 mol / L, and this parameter control can fully enable Cu ions to coordinate with Zn-MOF.

[0024] Furthermore, in step S3, the number-average molecular weight of the polyacrylonitrile is 1 million to 2 million. This molecular weight control allows the prepared carbon film to have suitable strength and modulus.

[0025] Furthermore, in step S3, Zn / Cu-ZIF is dissolved in an organic solvent, and then polymer powder is added. After stirring and mixing evenly, the mass concentration of Zn / Cu-ZIF is 0.04-0.12 g / mL, and the mass of the polymer powder is 0.1-0.2 g / mL. This parameter control can make the obtained porous fiber morphology uniform.

[0026] Furthermore, in step S3, during the electrospinning process, the voltage is ~5KV to 15KV, and the distance from the needle to the receiving shaft is 15cm. This parameter control can make the obtained fiber diameter uniform and controllable, and the obtained fiber membrane thickness uniform and controllable.

[0027] Furthermore, in step S4, the heat treatment temperature is 200–300°C and the time is 90–240 min. This parameter control can effectively enhance the mechanical strength and thermal stability of the fiber.

[0028] Furthermore, in step S4, during the vacuum calcination process, the calcination temperature is 800–1200°C and the calcination time is 2–4 hours. This parameter control can fully carbonize the carbon fiber film and reduce the metal. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1This is a schematic flowchart of a method for preparing a porous carbon-confined monodisperse copper / carbon fiber composite material according to the present invention.

[0031] Figure 2 SEM images of pure carbon fiber cloth and Cu / PPCs prepared in Comparative Example 1 and Example 1 are shown, where (a) is an SEM image of pure carbon fiber cloth prepared in Comparative Example 1; (b) is an SEM image of Zn / Cu-ZIF particles prepared in Example 1; and (c) and (d) are SEM images of Cu / PPCs prepared in Example 1 at different magnifications.

[0032] Figure 3 TEM image of Cu / PPCs prepared in Example 1;

[0033] Figure 4 Cyclic stability diagrams of pure carbon fibers and Cu / PPCs prepared in Comparative Example 1(b) and Example 1(a) for use in aqueous zinc-ion batteries. Detailed Implementation

[0034] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0035] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0036] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0037] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0038] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0039] like Figure 1 As shown, this invention provides a method for preparing a porous carbon-confined monodisperse copper / carbon fiber composite material, comprising the following steps:

[0040] S1: Mix zinc salt solution and dimethylimidazole solution evenly in aqueous solution, sonicate, let stand, then centrifuge, wash and dry to obtain Zn-ZIF particles;

[0041] The zinc salt is one or two of zinc nitrate hexahydrate, anhydrous zinc acetate, or zinc acetate dihydrate. In the mixed solution, the concentration of the zinc salt is 0.05–0.25 mol / L, and the concentration of dimethylimidazole is 0.25–0.5 mol / L. The settling time is 2–4 h. The centrifugation speed is 6000–10000 r / min. Preferably, the zinc salt is zinc acetate dihydrate, the concentration of the zinc salt is 0.025 mol / L, the concentration of dimethylimidazole is 0.25 mol / L, the mixture is sonicated for 1 min, and the settling time is 3 h. Finally, the mixture is centrifuged and dried to obtain Zn-ZIF particles.

[0042] S2: Zn-ZIF particles are placed in a copper salt solution of a certain concentration, sonicated for a certain time, then collected by centrifugation and dried to obtain Zn / Cu-ZIF particles;

[0043] The copper salt is one or both of copper nitrate and copper acetate, and the concentration of the copper salt in the mixed solution is 0.005–0.05 mol / L. The solvent is one of deionized water, ethanol, or methanol. The ultrasonication time is 1–6 h. The centrifugation speed is 3000–6000 r / min.

[0044] S3: Zn / Cu-ZIF powder is fully dissolved in an organic solvent by ultrasound, and then polymer powder is added and stirred to obtain a mixed solution. The mixed solution is then used to prepare precursor fibers by electrospinning.

[0045] The polymer is polyacrylonitrile, the number average molecular weight of which is 1 million to 2 million, and the organic solvent is N,N-dimethylformamide (DMF).

[0046] The Zn / Cu-ZIF particles have a mass of 0.2–0.6 g, the polymer powder has a mass of 0.5–1.0 g, the organic solvent has a mass of 5 ml, and the ultrasonic time is 1–4 h.

[0047] The stirring conditions for preparing the mixed solution by adding the polymer powder are water bath stirring at about 60°C or magnetic stirring at room temperature, and the dissolution time is 6 hours of water bath stirring at 60°C or 12 hours of stirring at room temperature. The stirring is slow, usually 50-100 r / min.

[0048] In the electrospinning process, the injection speed is 0.02-0.1 mm / min, the receiving roller speed is 140-2000 r / min, the voltage is ~5KV-15KV, the distance from the needle to the receiving shaft is 15 cm, and the needle diameter is 19-22 G.

[0049] S4: The precursor fibers are dried and transferred to a muffle furnace, heated to 200–300°C in air, and held at that temperature for 90–240 minutes to obtain pre-oxidized precursor fibers. The drying is performed under vacuum for 6–12 hours at a temperature of 60–90°C, with the muffle furnace heating rate being 1–5°C. This invention, by performing pre-oxidation treatment during the preparation of energy storage materials, effectively prevents problems such as "melt adhesion" of the fibers, ensuring the microstructural stability and conductivity of the material.

[0050] S5: The pre-oxidized precursor fiber is further subjected to vacuum calcination. Then, the product obtained after high-temperature carbonization is immersed in hydrochloric acid solution to remove residual metal particles on the surface, followed by multiple washings with deionized water, and then dried in a forced-air drying oven at 60°C for 4 hours to obtain porous carbon-confined monodisperse copper / carbon fiber composite material (Cu / PPCs);

[0051] The vacuum calcination atmosphere is either argon or nitrogen, the heating rate is 2–5°C, the calcination temperature is 800–1200°C, and the holding time is 2–4 hours. The concentration of the hydrochloric acid solution is 0.1–1 mol / L, and the immersion time in the hydrochloric acid solution is 12–24 hours. Because carbon materials are sensitive to oxygen, it is necessary to isolate them from oxygen. Calcination in argon or nitrogen also helps prevent metal oxidation.

[0052] This invention discloses a method for preparing porous carbon-confined monodisperse copper / carbon fiber energy storage materials. By introducing Zn / Cu-ZIF as a porous carbon precursor to modify pure carbon fibers, combined with optimized preparation processes, the pore volume and specific surface area of ​​the material are effectively improved, providing a three-dimensional space to accommodate zinc dendrites. Furthermore, the introduced monodisperse copper serves as a zinc ion deposition site, effectively improving the shortcomings of pure carbon materials as anodes in zinc-ion batteries. This invention addresses the deficiencies of single carbon fiber materials by adding Zn / Cu-ZIF powder with a specific structure, followed by high-temperature carbonization, to obtain porous carbon fibers with large pore volumes. The three-dimensional porous structure can accommodate zinc dendrites growing during charge and discharge. In addition, the zinc-loving monodisperse copper generated after Zn / Cu-ZIF carbonization attracts zinc ions to preferentially deposit on the porous carbon fibers, further optimizing the high conductivity of the carbon fibers. This invention selects Zn-MOF with a low boiling point as a template, further loading high-boiling-point active metal particles. During subsequent high-temperature processing, the zinc metal volatilizes, forming porous carbon, while the active metal particles remain. This invention employs electrospinning technology to synthesize porous carbon fibers in one step. By adding an appropriate mass of Zn / Cu-ZIF particles, the pore volume of the porous carbon fibers can be controlled, resulting in metal ion-doped porous carbon with a high specific surface area. This method is universal; by preparing ZIF / MOF powders with different metal ions, porous carbon fibers doped with different metal particles can be synthesized. The preparation method of this invention has advantages such as ease of control, low cost, and low energy consumption, and can significantly improve the specific surface area and physical strength of carbon cloth, thus making it suitable for applications in energy storage devices such as supercapacitors, lithium-ion batteries, and fuel cells. The obtained Cu / PPCs are flexible carbon fiber cloths, which are expected to be used in future flexible devices.

[0053] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0054] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0055] Example 1

[0056] A method for preparing a porous carbon-confined monodisperse copper / carbon fiber composite material includes the following steps:

[0057] (1) Weigh 0.025 mol / L Zn(COO)2·2H2O and dissolve it in 100 mL of deionized water, and denote it as solution A; weigh 0.25 mol / L 2-methylimidazole and dissolve it in 100 mL of deionized water, and denote it as solution B. Then, quickly pour solution B into solution A and stir for 5 min to obtain a mixed solution; sonicate the mixed solution for 1 min, let it stand for 3 h, centrifuge it at 10000 r / min for 10 min, and wash it twice with deionized water and ethanol respectively. Place the precipitate in a forced-air drying oven for 12 h to obtain white Zn-ZIF powder.

[0058] (2) Weigh out 0.005 mol / L copper acetate solution and dissolve it in 50 ml of ethanol. Place the prepared Zn-ZIF particles in the copper acetate ethanol solution, mix well, and sonicate for 2 h. Then centrifuge at 4000 r / min for 3 min. The resulting precipitate is dried in a forced-air drying oven for 3 h to obtain Zn / Cu-ZIF powder. The SEM image of the Zn / Cu-ZIF powder is shown below. Figure 2 As shown in b.

[0059] (3) At room temperature, 0.3 g of Zn / Cu-ZIF powder was dissolved in 5 mL of DMF and sonicated for 1 h to ensure uniform mixing of Zn / Cu-ZIF powder and DMF. Then, 0.8 g of polyacrylonitrile (PAN) powder with a molecular weight of 1.5 million was added to the Zn / Cu-ZIF DMF mixed solution and stirred at 100 r / min at room temperature for 12 hours until completely dissolved. The solution was a light milky white liquid, which was Zn / Cu-ZIF / PAN / DMF.

[0060] (4) Use a 5ml medical syringe to draw 5ml of the prepared Zn / Cu-ZIF / PAN / DMF solution. The hollow metal needle of the syringe is a 21G needle. Fix the needle and connect it to the high voltage positive power supply and the high voltage negative power supply respectively. The needle tilt angle is 15° respectively. Control the extrusion rate to be 0.08mm / min respectively. Perform electrospinning under voltage conditions of 10kV and ~2kV. The distance from the needle to the receiving shaft is 15cm. After normal filament extrusion, the continuously oriented precursor fiber cloth is received on the winding roller at a rate of 140r / min.

[0061] (5) The above precursor fibers were dried in a vacuum drying oven at 60°C for 6 hours. Then, under an air atmosphere, the pre-oxidation (pre-oxidation treatment) heating rate was fixed at 1°C / min. The precursor fibers were placed in a high-temperature oven and heated from 20°C to 240°C and held for 90 minutes to obtain pre-oxidized precursor fiber cloth. Then, high-temperature sintering was performed. Under a nitrogen atmosphere, the pre-oxidized fiber cloth was heated from room temperature to 1000°C at a heating rate of 5°C / min and held for 2 hours. The product after high-temperature sintering was soaked in 0.1 mol / L hydrochloric acid solution for 12 hours to remove residual metal on the surface. Then, the carbon fiber composite material was washed with deionized water until neutral and dried to obtain porous confined monodisperse copper / carbon fiber composite material (Cu / PPCs).

[0062] Example 2

[0063] A method for preparing a porous carbon-confined monodisperse copper carbon fiber composite material includes the following steps:

[0064] (1) Weigh 0.025 mol / L Zn(NO3)2·2H2O and dissolve it in 100 mL of deionized water, and denote it as solution A; weigh 0.35 mol / L 2-methylimidazole and dissolve it in 100 mL of deionized water, and denote it as solution B. Then, quickly pour solution B into solution A and stir for 5 min to obtain a mixed solution; after the mixed solution has stood for 2 h, centrifuge it at 10000 r / min for 10 min, and wash it twice with deionized water and ethanol respectively. Place the precipitate in a forced-air drying oven for 12 h to obtain white Zn-ZIF powder.

[0065] (2) Weigh 0.005 mol / L copper acetate solution and dissolve it in 50 ml of ethanol. Place the prepared Zn-ZIF particles in the solution, mix them evenly, and sonicate for 4 h. Then centrifuge at 4000 r / min for 3 min. The resulting precipitate is dried in a forced-air drying oven for 3 h to obtain Zn / Cu-ZIF powder.

[0066] (3) At room temperature, 0.2 g of Zn / Cu-ZIF powder was dissolved in 5 ml of DMF and sonicated for 2 h to ensure uniform mixing of Zn / Cu-ZIF powder and DMF. Then, 0.8 g of polyacrylonitrile (PAN) powder with a molecular weight of 1.5 million was added to the Zn / Cu-ZIF / DMF mixed solution and stirred at 100 r / min at room temperature for 12 hours until completely dissolved. The solution was a light milky white liquid (Zn / Cu-ZIF / PAN / DMF).

[0067] (4) Use a 5ml medical syringe to draw 5ml of the prepared Zn / Cu-ZIF / PAN / DMF solution. The hollow metal needle of the syringe is a 21G needle. Fix the needle and connect it to the high voltage positive power supply and the high voltage negative power supply respectively. The needle tilt angle is 15° respectively. Control the extrusion rate to be 0.05mm / min respectively. Perform electrospinning under voltage conditions of 10kV and ~2kV. The distance from the needle to the receiving shaft is 15cm. After normal filament output, the continuously oriented precursor fiber cloth is received on the winding roller at a rate of 140r / min.

[0068] (5) The above precursor fibers were dried in a vacuum drying oven at 90°C for 6 hours. Then, under an air atmosphere, the pre-oxidation (pre-oxidation treatment) heating rate was fixed at 1°C / min. The precursor fiber bundle was placed in a high-temperature oven and heated from 20°C to 240°C and held for 90 minutes to obtain the pre-oxidized precursor fiber cloth. Then, a high-temperature sintering treatment was performed. Under a nitrogen atmosphere, the pre-oxidized fiber cloth was heated from room temperature to 1000°C at a heating rate of 3°C / min and held for 2 hours. The obtained porous confined monodisperse copper / carbon fiber composite material was soaked in 0.5 mol / L hydrochloric acid solution for 18 hours to remove residual metal on the surface. Then, the carbon fiber composite material was washed with deionized water until neutral to obtain Cu / PPCs.

[0069] Example 3

[0070] A method for preparing a porous carbon-confined monodisperse copper / carbon fiber composite material includes the following steps:

[0071] (1) Weigh 0.02 mol / L Zn(NO3)2·2H2O and dissolve it in 100 mL of deionized water, and denote it as solution A; weigh 0.5 mol / L 2-methylimidazole and dissolve it in 100 mL of deionized water, and denote it as solution B. Then, quickly pour solution B into solution A and stir for 5 min to obtain a mixed solution; after the mixed solution has stood for 3 h, centrifuge it at 8000 r / min for 10 min, and wash it twice with deionized water and ethanol respectively. Place the precipitate in a forced-air drying oven for 12 h to obtain white Zn-ZIF powder.

[0072] (2) Weigh 0.02 mol / L copper acetate solution and dissolve it in 50 ml of ethanol. Place the prepared Zn-ZIF particles in the solution, mix them evenly, and sonicate for 1 h. Then centrifuge at 6000 r / min for 3 min. The resulting precipitate is dried in a forced-air drying oven for 3 h to obtain Zn / Cu-ZIF powder.

[0073] (3) At room temperature, 0.2 g of Zn / Cu-ZIF powder was dissolved in 5 ml of DMF and sonicated for 1 h to ensure that the Zn / Cu-ZIF powder and DMF were mixed evenly. Then, 0.5 g of polyacrylonitrile (PAN) powder with a molecular weight of 2 million was added to the mixed solution of Zn / Cu-ZIF and DMF, and stirred at 50 r / min at room temperature for 12 hours until completely dissolved. The solution was a light milky white liquid (Zn / Cu-ZIF / PAN / DMF).

[0074] (4) Use a 5ml medical syringe to draw 5ml of the prepared Zn / Cu-ZIF / PAN / DMF solution. The hollow metal needle of the syringe is a 21G needle. Fix the needle and connect it to the high voltage positive power supply and the high voltage negative power supply respectively. The needle tilt angle is 15° respectively. Control the extrusion rate to be 0.08mm / min respectively. Perform electrospinning under voltage conditions of 10kV and ~2kV. The distance from the needle to the receiving shaft is 15cm. After normal filament output, the continuously oriented precursor fiber cloth is received on the winding roller at a rate of 500r / min.

[0075] (5) The above precursor fibers were dried in a vacuum drying oven at 60°C for 6 hours. Then, under an air atmosphere, the pre-oxidation (pre-oxidation treatment) heating rate was fixed at 5°C / min. The precursor fiber bundle was placed in a high-temperature oven and heated from 20°C to 240°C and held for 90 minutes to obtain the pre-oxidized precursor fiber cloth. Then, a high-temperature sintering treatment was performed. Under a nitrogen atmosphere, the pre-oxidized fiber cloth was heated from room temperature to 1000°C at a heating rate of 2°C / min and held for 2 hours. The obtained porous confined monodisperse copper / carbon fiber composite material was soaked in 0.1 mol / L hydrochloric acid solution for 24 hours to remove residual metal on the surface. Then, the carbon fiber composite material was washed with deionized water until neutral to obtain Cu / PPCs.

[0076] Example 4

[0077] A method for preparing a porous carbon-confined monodisperse copper / carbon fiber composite material includes the following steps:

[0078] (1) Weigh 0.05 mol / L Zn(NO)3·6H2O and dissolve it in 100 mL of deionized water, and denote it as solution A; weigh 0.5 mol / L 2-methylimidazole and dissolve it in 100 mL of deionized water, and denote it as solution B. Then, quickly pour solution B into solution A and stir for 5 min to obtain a mixed solution; after the mixed solution has stood for 3 h, centrifuge it at 10000 r / min for 10 min, and wash it twice with deionized water and ethanol respectively. Place the precipitate in a forced-air drying oven for 12 h to obtain white Zn-ZIF powder.

[0079] (2) Weigh 0.04 mol / L copper nitrate solution and dissolve it in 50 ml methanol. Place the prepared Zn-ZIF particles in the solution, mix them evenly, and sonicate for 6 h. Then centrifuge at 6000 r / min for 3 min. The resulting precipitate is dried in a forced-air drying oven for 3 h to obtain Zn / Cu-ZIF powder.

[0080] (3) At room temperature, 0.6 g of Zn / Cu-ZIF powder was dissolved in 5 ml of DMF and sonicated for 1 h to ensure uniform mixing of Zn / Cu-ZIF powder and DMF. Then, 1.0 g of polyacrylonitrile (PAN) powder with a molecular weight of 1 million was added to the Zn / Cu-ZIF / DMF mixed solution and stirred at 80 r / min at room temperature for 12 hours until completely dissolved, resulting in a light milky white liquid (Zn / Cu-ZIF / PAN / DMF).

[0081] (4) Use a 5ml medical syringe to draw 5ml of the prepared Zn / Cu-ZIF / PAN / DMF solution. The hollow metal needle of the syringe is a 22G needle. Fix the needle and connect it to the high voltage positive power supply and the high voltage negative power supply respectively. The needle tilt angle is 15° respectively. Control the extrusion rate to be 0.02mm / min. Perform electrospinning under voltage conditions of 10kV and ~2kV. The distance from the needle to the receiving shaft is 15cm. After normal filament output, the continuously oriented precursor fiber cloth is received on the winding roller at a rate of 2000r / min.

[0082] (5) The above precursor fibers were dried in a vacuum drying oven at 80°C for 8 hours. Then, under an air atmosphere, the pre-oxidation (pre-oxidation treatment) heating rate was fixed at 1°C / min. The precursor fiber bundle was placed in a high-temperature oven and heated from 20°C to 200°C and held for 180 minutes to obtain the pre-oxidized precursor fiber cloth. Then, a high-temperature sintering treatment was performed. Under a nitrogen atmosphere, the pre-oxidized fiber cloth was heated from room temperature to 1000°C at a heating rate of 2°C / min and held for 3 hours. The obtained porous confined monodisperse copper / carbon fiber composite material was soaked in a 1 mol / L hydrochloric acid solution for 12 hours to remove residual metal on the surface. Then, the carbon fiber composite material was washed with deionized water until neutral to obtain Cu / PPCs.

[0083] Example 5

[0084] A method for preparing a porous carbon-confined monodisperse copper / carbon fiber composite material includes the following steps:

[0085] (1) Weigh 0.05 mol / L Zn(COO)2·2H2O and dissolve it in 100 mL of deionized water, and denote it as solution A; weigh 0.5 mol / L 2-methylimidazole and dissolve it in 100 mL of deionized water, and denote it as solution B. Then, quickly pour solution B into solution A and stir for 5 min to obtain a mixed solution; after the mixed solution has stood for 5 h, centrifuge it at 6000 r / min for 10 min, and wash it twice with deionized water and ethanol respectively. Place the precipitate in a forced-air drying oven for 12 h to obtain white Zn-ZIF powder.

[0086] (2) Weigh 0.05 mol / L copper acetate solution and dissolve it in 50 ml of deionized water. Place the prepared Zn-ZIF particles in the solution, mix them evenly, and sonicate for 2 h. Then centrifuge at 3000 r / min for 3 min. The resulting precipitate is dried in a forced-air drying oven for 3 h to obtain Zn / Cu-ZIF powder.

[0087] (3) At room temperature, 0.6 g of Zn / Cu-ZIF powder was dissolved in 5 ml of DMF and sonicated for 4 h to ensure uniform mixing of Zn / Cu-ZIF powder and DMF. Then, 0.8 g of polyacrylonitrile (PAN) powder with a molecular weight of 1.5 million was added to the Zn / Cu-ZIF / DMF mixed solution and stirred in a water bath at 100 r / min at 60 °C for 6 hours until completely dissolved. The solution was a light milky white liquid (Zn / Cu-ZIF / PAN / DMF).

[0088] (4) Use a 5ml medical syringe to draw 5ml of the prepared Zn / Cu-ZIF / PAN / DMF solution. The hollow metal needle of the syringe is a 19G needle. Fix the needle and connect it to the high voltage positive power supply and the high voltage negative power supply respectively. The needle tilt angle is 15° respectively. Control the extrusion rate to be 0.1mm / min respectively. Perform electrospinning under voltage conditions of 10kV and ~2kV. The distance from the needle to the receiving shaft is 15cm. After normal filament output, the continuously oriented precursor fiber cloth is received on the winding roller at a rate of 140r / min.

[0089] (5) The above precursor fibers were dried in a vacuum drying oven at 60°C for 6 hours. Then, under an air atmosphere, the pre-oxidation (pre-oxidation treatment) heating rate was fixed at 3°C / min. The precursor fiber bundle was placed in a high-temperature oven and heated from 20°C to 240°C and held for 90 minutes to obtain the pre-oxidized precursor fiber cloth. Then, a high-temperature sintering treatment was performed. Under a nitrogen atmosphere, the pre-oxidized fiber cloth was heated from room temperature to 1200°C at a heating rate of 5°C / min and held for 2 hours. The obtained porous confined monodisperse copper / carbon fiber composite material was soaked in 0.8 mol / L hydrochloric acid solution for 12 hours to remove residual metal on the surface. Then, the carbon fiber composite material was washed with deionized water until neutral to obtain Cu / PPCs.

[0090] Example 6

[0091] A method for preparing a porous carbon-confined monodisperse copper / carbon fiber composite material includes the following steps:

[0092] (1) Weigh 0.25 mol / L Zn(COO)2·2H2O and dissolve it in 100 mL of deionized water, and denote it as solution A; weigh 2.5 mol / L 2-methylimidazole and dissolve it in 100 mL of deionized water, and denote it as solution B. Then, quickly pour solution B into solution A and stir for 5 min to obtain a mixed solution; after the mixed solution has stood for 3 h, centrifuge it at 10000 r / min for 10 min, and wash it twice with deionized water and ethanol respectively. Place the precipitate in a forced-air drying oven for 12 h to obtain white Zn-ZIF powder.

[0093] (2) Weigh 0.01 mol / L copper acetate solution and dissolve it in 50 ml of ethanol. Place the prepared Zn-ZIF particles in the solution, mix them evenly, and sonicate for 4 h. Then centrifuge at 4000 r / min for 3 min. The resulting precipitate is dried in a forced-air drying oven for 3 h to obtain Zn / Cu-ZIF powder.

[0094] (3) At room temperature, 0.3 g of Zn / Cu-ZIF powder was dissolved in 5 ml of DMF and sonicated for 1 h to ensure that the Zn / Cu-ZIF powder and DMF were mixed evenly. Then, 0.8 g of polyacrylonitrile (PAN) powder was added to the Zn / Cu-ZIF / DMF mixed solution and stirred at 100 r / min at room temperature for 12 hours until completely dissolved. The solution was a light milky white liquid (Zn / Cu-ZIF / PAN / DMF).

[0095] (4) Use a 5ml medical syringe to draw 5ml of the prepared Zn / Cu-ZIF / PAN / DMF solution. The hollow metal needle of the syringe is a 21G needle. Fix the needle and connect it to the high voltage positive power supply and the high voltage negative power supply respectively. The needle tilt angle is 15° respectively. Control the extrusion rate to be 0.05mm / min and 1.0ml / h respectively. Perform electrospinning under voltage conditions of 10kV and ~2kV. The distance from the needle to the receiving shaft is 15cm. After normal filament output, the continuously oriented precursor fiber cloth is received on the winding roller at a rate of 500r / min.

[0096] (5) The above precursor fibers were dried in a vacuum drying oven at 60°C for 12 hours. Then, under an air atmosphere, the pre-oxidation (pre-oxidation treatment) heating rate was fixed at 2°C / min. The precursor fiber bundle was placed in a high-temperature oven and heated from 20°C to 200°C and held for 200 minutes to obtain the pre-oxidized precursor fiber cloth. Then, a high-temperature sintering treatment was performed. Under a nitrogen atmosphere, the pre-oxidized fiber cloth was heated from room temperature to 900°C at a heating rate of 5°C / min and held for 3 hours. The obtained porous confined monodisperse copper / carbon fiber composite material was soaked in 0.5 mol / L hydrochloric acid solution for 12 hours to remove residual metal on the surface. Then, the carbon fiber composite material was washed with deionized water until neutral to obtain Cu / PPCs.

[0097] Example 7

[0098] A method for preparing a porous carbon-confined monodisperse copper / carbon fiber composite material includes the following steps:

[0099] (1) Weigh 0.25 mol / L Zn(COO)2 and dissolve it in 100 mL of deionized water, and denote it as solution A; weigh 2.5 mol / L 2-methylimidazole and dissolve it in 100 mL of deionized water, and denote it as solution B. Then, quickly pour solution B into solution A and stir for 5 min to obtain a mixed solution; after the mixed solution has stood for 3 h, centrifuge it at 10000 r / min for 10 min, and wash it twice with deionized water and ethanol respectively. Place the precipitate in a forced-air drying oven for 12 h to obtain white Zn-ZIF powder.

[0100] (2) Weigh 0.03 mol / L copper acetate solution and dissolve it in 50 ml of ethanol. Place the prepared Zn-ZIF particles in the solution, mix them evenly, and sonicate for 4 h. Then centrifuge at 4000 r / min for 3 min. The resulting precipitate is dried in a forced-air drying oven for 3 h to obtain Zn / Cu-ZIF powder.

[0101] (3) At room temperature, 0.6 g of Zn / Cu-ZIF powder was dissolved in 5 ml of DMF and sonicated for 1 h to ensure uniform mixing of Zn / Cu-ZIF powder and DMF. Then, 0.8 g of polyacrylonitrile (PAN) powder was added to the Zn / Cu-ZIF / DMF mixed solution and stirred at 100 r / min at room temperature for 12 hours until completely dissolved, resulting in a pale milky white liquid (Zn / Cu-ZIF / PAN / DMF).

[0102] (4) Use a 5ml medical syringe to draw 5ml of the prepared Zn / Cu-ZIF / PAN / DMF solution. The hollow metal needle of the syringe is a 20G needle. Fix the needle and connect it to the high voltage positive power supply and the high voltage negative power supply respectively. The needle tilt angle is 15° respectively. Control the extrusion rate to be 0.05mm / min and 1.0ml / h respectively. Perform electrospinning under voltage conditions of 10kV and ~2kV. The distance from the needle to the receiving shaft is 15cm. After normal filament output, the continuously oriented precursor fiber cloth is received on the winding roller at a rate of 2000r / min.

[0103] (5) The above precursor fibers were dried in a vacuum drying oven at 60°C for 6 hours. Then, under an air atmosphere, the pre-oxidation (pre-oxidation treatment) heating rate was fixed at 5°C / min. The precursor fiber bundle was placed in a high-temperature oven and heated from 20°C to 220°C and held for 120 minutes to obtain the pre-oxidized precursor fiber cloth. Then, a high-temperature sintering treatment was performed. Under a nitrogen atmosphere, the pre-oxidized fiber cloth was heated from room temperature to 800°C at a heating rate of 5°C / min and held for 4 hours. The obtained porous confined monodisperse copper / carbon fiber composite material was soaked in 0.5 mol / L hydrochloric acid solution for 12 hours to remove residual metal on the surface. Then, the carbon fiber composite material was washed with deionized water until neutral to obtain Cu / PPCs.

[0104] Comparative Example 1

[0105] A method for preparing a pure carbon fiber composite material includes the following steps:

[0106] (1) At room temperature, add 0.8g of polyacrylonitrile (PAN) powder to 5ml of DMF and stir at 100r / min for 12h until completely dissolved. The solution is a pale yellow transparent liquid.

[0107] (2) Use a 5ml medical syringe to draw 5ml of the prepared PAN / DMF solution. The hollow metal needle of the syringe is a 21G needle. Fix the needle and connect it to the high voltage positive power supply and the high voltage negative power supply respectively. The needle tilt angle is 15° respectively. Control the extrusion rate to be 0.08mm / min and 1.0ml / h respectively. Perform electrospinning under voltage conditions of 12kV and ~2kV. After normal filament output, receive the continuously oriented precursor fiber cloth on the winding roller at a rate of 500r / min.

[0108] (3) The precursor fibers were dried in a vacuum drying oven at 60℃ for 6 hours. Then, under an air atmosphere, the pre-oxidation (pre-oxidation treatment) heating rate was fixed at 1℃ / min. The precursor fiber bundle was placed in a high-temperature oven and heated from 20℃ to 240℃, and held for 90 minutes to obtain a pre-oxidized precursor fiber cloth. Then, a high-temperature sintering treatment was performed. Under a nitrogen atmosphere, the pre-oxidized fiber cloth was heated from room temperature to 1000℃ at a heating rate of 5℃ / min and held for 2 hours. The result was a flexible pure carbon nanofiber cloth with an average diameter of 500nm. (Related product references are available.) Figure 2 a.

[0109] Figure 2 (a) is a SEM image of the pure carbon fiber cloth prepared in Comparative Example 1. Figure 2 (b) is a SEM image of the Zn / Cu-ZIF particles prepared in Example 1. Figure 2 (c) and (d) are SEM images of the Cu / PPCs carbon fiber cloth prepared in Example 1 at different magnifications. Figure 2 It can be seen that,

[0110] The average diameter of this porous, confined, monodisperse copper / carbon fiber composite material is approximately 500 nm; SEM images of this product are shown below. Figure 2 c~d, by Figure 2 As shown in c to d, the obtained porous fibers have a uniform diameter and uniform particle distribution among the fibers. Such uniform porous carbon fiber cloth can restrict the vertical growth of dendrites, and monodisperse copper can guide zinc ions to preferentially deposit on the carbon fiber cloth, thus inhibiting the dendrite growth of the zinc anode.

[0111] Pure carbon fiber cloth has a diameter of about 300 nm and a smooth surface. Zn / Cu-ZIF exhibits a truncated tetrahedral morphology with a size of about 300 nm and a uniform size distribution. Cu / PPCs carbon fiber cloth has a diameter of about 500 nm, which is due to the incorporation of Zn / Cu-ZIF particles. Zn / Cu-ZIF is densely arranged and uniformly dispersed in the fiber. This structure is beneficial for inhibiting the vertical growth of zinc dendrites. The carbon cages derived from Zn / Cu-ZIF also contain monodisperse copper, which can act as a zinc-loving source to attract zinc ion deposition.

[0112] Figure 3 The image shown is a TEM image of the Cu / PPCs carbon fiber cloth prepared in Example 1. Figure 3 It is known that the Cu / PPCs carbon fiber cloth obtained after high-temperature carbonization forms a hollow cavity containing monodisperse copper. This structure can act as a zinc-loving source to attract zinc ion deposition, which is beneficial to suppressing the vertical growth of zinc dendrites.

[0113] Figure 4 The results show the cycle stability test results of symmetric cells assembled from Cu / PPCs prepared in Example 1 and PPCs prepared in Comparative Example 1. Figure 4 It can be seen that Cu / PPCs have smaller polarization and longer cycle life.

[0114] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. Use of a porous carbon-confined monodisperse copper / carbon fiber composite in a negative electrode material for aqueous zinc ion batteries, characterized in that, The preparation method of the porous carbon confined monodisperse copper / carbon fiber composite comprises the following steps: S1: uniformly mixing a zinc salt solution and a dimethyl imidazole solution, standing after ultrasonic treatment, and preparing Zn-ZIF; S2: dissolving a copper salt solution in a solvent to obtain a solution, placing the Zn-ZIF in the solution, and preparing Zn / Cu-ZIF through ultrasonic treatment and centrifugal treatment; the copper salt is copper nitrate and / or copper acetate; the concentration of the copper salt solution is 0.005-0.05 mol / L; the solvent is one of deionized water, ethanol or methanol; the ultrasonic treatment time is 1-6 h; and the centrifugal speed is 3000-6000 r / min; S3: dissolving the Zn / Cu-ZIF in an organic solvent, then adding polyacrylonitrile powder, uniformly stirring and mixing, and then preparing a precursor fiber through electrospinning; the receiving roller speed during the electrospinning process is 140-2000 r / min; S4: drying the precursor fiber, then performing heat treatment to obtain a pre-oxidized precursor fiber, calcining the pre-oxidized precursor fiber under a nitrogen atmosphere, then immersing the obtained product after calcination in a hydrochloric acid solution, the concentration of the hydrochloric acid solution being 0.1-1 mol / L, and the immersion time in the hydrochloric acid solution being 12-24 h, to obtain Cu / PPCs.

2. The use of the porous carbon-confined monodisperse copper / carbon fiber composite material according to claim 1 in the negative electrode material of a water-based zinc ion battery, characterized in that, In step S1, the zinc salt is one or two of zinc nitrate hexahydrate, anhydrous zinc acetate or zinc acetate dihydrate; in the mixed solution of the zinc salt solution and the dimethyl imidazole, the concentration of the zinc salt is 0.05-0.25 mol / L, and the concentration of the dimethyl imidazole is 0.25-0.5 mol / L.

3. Use of the porous carbon-confined monodisperse copper / carbon fiber composite material according to claim 1 as a negative electrode material for aqueous zinc ion batteries, characterized in that, In step S3, the number average molecular weight of the polyacrylonitrile is 1-2 million.

4. The use of the porous carbon-confined monodisperse copper / carbon fiber composite material according to claim 1 in the negative electrode material of a water-based zinc ion battery, characterized in that, In step S3, the Zn / Cu-ZIF is dissolved in an organic solvent, then the polyacrylonitrile powder is added, and after uniform stirring and mixing, the mass concentration of the Zn / Cu-ZIF is 0.04-0.12 g / mL, and the mass of the polyacrylonitrile powder is 0.1-0.2 g / mL.

5. The use of the porous carbon-confined monodisperse copper / carbon fiber composite material according to claim 1 in the negative electrode material of a water-based zinc ion battery, characterized in that, In step S3, during the electrospinning process, the distance from the needle to the receiving roller is 15 cm.

6. Use of the porous carbon-confined monodisperse copper / carbon fiber composite material according to claim 1 as a negative electrode material for aqueous zinc ion batteries, characterized in that, In step S4, the heat treatment temperature is 200-300 DEG C, and the time is 90-240 min.

7. Use of the porous carbon-confined monodisperse copper / carbon fiber composite material according to claim 1 as a negative electrode material for aqueous zinc ion batteries, characterized in that, In step S4, during the calcination process, the calcination temperature is 800-1200 DEG C, and the calcination time is 2-4 h.

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