Preparation method and application of graphene / pedot composite fiber with synergistic enhancement of electron / ion transmission

Abstract

The application relates to a preparation method and application of graphene / PEDOT composite fibers with synergistically enhanced electron / ion transmission, and relates to the field of capacitors. First, graphene gel is prepared through self-assembly of a graphene oxide precursor, and the graphene gel is disassembled into graphene microgel; then, the graphene gel microzone is wrapped in a PEDOT skeleton with electronic / ion conductor characteristics through the assembly characteristics of poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS). The composite fibers prepared through the "assembly-disassembly-reassembly" method take the PEDOT conductive skeleton as a high-speed channel for electron and ion transmission, can effectively shorten the transmission distance from the electrode surface to the inside, and the graphene gel microzone with a three-dimensional spatial configuration can provide effective ion diffusion microchannels and ensure the full exposure of the graphene surface and oxygen active functional groups. Through synergistic regulation of the multistage structure, the charging / discharging reaction efficiency is significantly improved.

Description

Technical Field

[0001] This invention belongs to the fields of materials and fibrous zinc-ion capacitors, and relates to the preparation and application of a composite fiber electrode material. More specifically, it relates to a method for preparing an electron / ion transport synergistic enhanced graphene / PEDOT composite fiber and its application in a fibrous zinc-ion capacitor. Background Technology

[0002] With the booming development of the wearable electronics industry and the rapid upgrading of portable electronic devices, flexible energy storage devices capable of storing energy for these electronic products are rapidly developing towards lightweight, environmentally friendly, and high energy and power density. Zinc-ion capacitors are a novel type of energy storage device positioned between supercapacitors and ion batteries. Compared to traditional energy storage devices such as ion batteries and supercapacitors, all-solid-state fibrous zinc-ion capacitors have become a major research hotspot for scholars both domestically and internationally due to their excellent power and energy density, high safety, flexibility, weavability, and lightweight properties. Currently, the mismatch between the positive and negative electrode capacities of zinc-ion capacitors results in relatively low energy density, limiting the further development of fibrous zinc-ion capacitors. Therefore, developing high-performance capacitor positive electrode materials that can match the high capacity of the zinc negative electrode is an effective way to achieve high-performance fibrous zinc-ion capacitors.

[0003] Among various cathode materials, graphene fibers are a promising candidate for fibrous zinc-ion capacitor cathodes, possessing advantages such as large theoretical specific surface area, high conductivity, ease of assembly and chemical modification, and good flexibility. However, reduced graphene oxide (rGO) sheets are prone to stacking and have poor conductivity, limiting electron / ion transport and resulting in poor specific capacitance and rate performance. In previous research, we co-assembled graphene oxide with poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), which improved the capacitance performance of graphene to some extent. However, rGO still exhibits an ordered multilayer structure, limiting ion diffusion; moreover, the fibers are dominated by the rGO backbone, resulting in poor conductivity and affecting electron transfer. Therefore, further enhancing the electron transport and ion diffusion efficiency of rGO-based fiber electrodes to achieve a synergistic improvement in specific capacitance and rate performance is crucial for obtaining high energy density and power density fibrous zinc-ion capacitors to meet the application requirements of fast charging and long battery life in flexible electronic devices. Summary of the Invention

[0004] To address the shortcomings of existing technologies and solve the problem that conventional materials cannot meet people's needs, this invention provides a method for preparing and applying graphene / PEDOT composite fibers with synergistic enhancement of electron / ion transport.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing and applying a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport includes the following steps:

[0007] (1) Preparation of graphene precursor: Using graphite powder as raw material, graphene oxide precursor solution was prepared according to the improved Hummers method;

[0008] (2) Preparation of graphene gel microparticle suspension (assembly-disassembly): The graphene oxide precursor solution of a certain concentration in step (1) is subjected to hydrothermal reaction at a certain temperature for a period of time. After cooling, the reaction product is taken out and thoroughly washed with water to remove impurities, and graphene gel assembly is obtained. The obtained graphene gel is disassembled by stirring, sonication, ball milling or cell pulverization for a period of time to obtain graphene gel microparticle suspension. The four treatment methods correspond to four different three-dimensional structures and sizes of graphene gel microparticle suspension.

[0009] It should be noted that during the hydrothermal process of graphene oxide, doping sources or other precursors can be introduced to prepare doped graphene gels or graphene composite gels.

[0010] (3) Preparation (reassembly) of composite fibers: Take the graphene gel microparticle suspension from step (2) and poly(3,4-ethylenedioxythiophene): polystyrene sulfonic acid (PEDOT:PSS), mix them evenly by ultrasonication, add an acidic solution, and gel the mixture by vigorous oscillation. Inject the gel mixture into a silicone tube with a syringe, and hydrothermally heat it at a certain temperature for a period of time. After cooling, take out the obtained gel fibers from the silicone tube and soak them in concentrated sulfuric acid or organic solvent for a certain time to remove a large amount of PSS, thus obtaining the graphene / PEDOT composite fibers prepared by the "assembly-disassembly-reassembly" method.

[0011] (4) Washing: The graphene / PEDOT composite fiber obtained in step (3) is thoroughly washed with deionized water to remove impurities.

[0012] (5) Drying: Fix both ends of the washed fiber and dry it thoroughly at room temperature. It can be used directly as an electrode material.

[0013] In step (1), the graphite powder is 12000-325 mesh, and the concentration of the graphene oxide precursor solution is 1-15 mg / mL, preferably 2.0-6.0 mg / mL.

[0014] In step (2), the graphene precursor solution is one of the solutions in step (1), with the preferred concentration being 2.0-6.0 mg / mL, the hydrothermal reaction temperature being 140.0-200.0℃, the reaction time being 6.0-24.0 h, the magnetic stirring time being 0.5-72.0 h, the ultrasonic time being 0.5-5 h, the ball milling time being 0.5-5 h, the cell pulverization time being 0.1-1 h, and the graphene gel microparticle suspension concentration being 5-30 mg / mL.

[0015] The graphene gel microparticle suspension in step (3) is one of the suspensions in step (2). The mass ratio of the graphene gel microparticle suspension to the PEDOT:PSS raw material is 1:20-20:1, preferably 1:2-2:1.

[0016] In step (3), the acid in the acidic aqueous solution is one or more of sulfuric acid, hydrochloric acid, or hydroiodic acid, with a concentration of 0.01-5.0M, a hydrothermal reaction temperature of 60.0-120.0℃, a reaction time of 1.0-8.0h, and a soaking time of concentrated sulfuric acid or organic solvent of 3.0h-48.0h. The organic solvent refers to one or more of ethylene glycol, dimethyl sulfoxide, or tetrahydrofuran.

[0017] In step (5), washing refers to immersing the obtained graphene / PEDOT composite fiber in deionized water at room temperature.

[0018] In step (6), drying refers to fixing both ends of the washed composite fiber and drying it at room temperature for 4-12 hours to obtain graphene / PEDOT composite fiber.

[0019] This invention discloses a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport, primarily prepared using an "assembly-deassembly-reassembly" method. First, a graphene gel is prepared by self-assembly of a graphene oxide precursor, which is then deassembled into graphene microgels. Next, the assembly characteristics of PEDOT:PSS are utilized to composite the graphene gel microdomains within a PEDOT framework that possesses both electron and ion conductor properties. Compared to composite fibers prepared by a "one-time co-assembly" method using graphene oxide and PEDOT:PSS, the composite fiber prepared by the "assembly-deassembly-reassembly" method, under the same proportions, uses the PEDOT conductive framework as a high-speed channel for electron and ion transport, effectively shortening the transport distance from the electrode surface to the interior. The three-dimensional graphene gel microdomains provide effective ion diffusion microchannels, ensuring sufficient exposure of the graphene surface and oxygen-active functional groups. Through the synergistic regulation of multi-level structures, the electron and ion transport processes are dually regulated and effectively enhanced, significantly improving the charge-discharge reaction efficiency.

[0020] Compared with existing technologies, this application constructs a novel composite fiber electrode structure by embedding rGO microstructure units within a highly conductive PEDOT framework through a novel "assembly-deassembly-reassembly" strategy. This structure exhibits better conductivity and unobstructed ion diffusion channels, enabling a synergistic improvement in specific capacitance and rate performance. The method provided by this invention is low-cost, simple to prepare, and easily scalable for industrial production.

[0021] The graphene / PEDOT composite fiber of this application can be used as the positive electrode of a fibrous zinc-ion capacitor. Using the composite fiber as the positive electrode, zinc wire as the negative electrode, and a 2M zinc sulfate aqueous solution as the electrolyte, this composite fiber electrode exhibits high specific capacitance and excellent rate performance, far superior to composite fibers obtained through a single blending assembly. The graphene / PEDOT-based composite fiber electrode can be assembled with galvanized carbon fibers through winding or parallel arrangement to form an all-solid-state fibrous zinc-ion capacitor, possessing both high energy density and power density. Attached Figure Description

[0022] To provide a more detailed description of the technical solutions of the embodiments of this invention, the accompanying drawings used in the following description of the embodiments are briefly introduced. Obviously, the drawings in the following description are only drawings of some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on such drawings without creative effort.

[0023] Figure 1 This is a scanning electron microscope image of the cross-section of a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport according to the present invention after lyophilization.

[0024] Figure 2 This is a side scanning electron microscope image of a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport according to the present invention after freeze-drying.

[0025] Figure 3 This is a comparison of the volumetric specific capacity of graphene / PEDOT composite fiber electrodes prepared by two different assembly methods at different current densities.

[0026] Figure 4 This is a volumetric capacitance diagram of a graphene / PEDOT composite fiber-based all-solid-state zinc ion capacitor with synergistic enhancement of electron / ion transport according to the present invention, under different current densities.

[0027] Figure 5 This is a cyclic voltammetry (CV) diagram of a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport according to the present invention at different scan rates;

[0028] Figure 6This is a charge-discharge curve (GCD) of a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport under different current densities according to the present invention.

[0029] Figure 7 This is an AC impedance (EIS) diagram of a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport according to the present invention.

[0030] Figure 8 This is a Ragone diagram of a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport according to the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer and to enable those skilled in the art to better understand the present invention, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples.

[0032] Example 1

[0033] (1) Preparation of graphene precursor: Using 12000 mesh graphite powder as raw material, graphene oxide precursor solution was prepared according to the modified Hummers method; (2) Preparation of graphene microgel particle suspension: 50 mL of 2 mg / mL graphene oxide precursor solution was hydrothermally reacted at 180℃ for 12 h. After cooling, the reaction product was taken out and thoroughly washed with water to remove impurities. The reaction product was magnetically stirred for 48 h to obtain graphene microgel particle suspension; (3) Preparation of composite fiber by "assembly-disassembly-reassembly" method: 1 mL of 11 mg / mL graphene microgel particle suspension and 1 mL of 11 mg / mL poly(3,4-ethylenedioxythiophene): polystyrene sulfonic acid (PEDOT:PSS) was ultrasonically mixed for 30 min. 100.0 μL of 2.0 M sulfuric acid was added to 2.0 mL of the above mixture. The mixture was shaken vigorously for 2 min to gel. The air bubbles were removed with a vacuum water pump. The gel mixture was injected into a silicone tube with a syringe. The mixture was hydrothermally reacted at 90 °C for 3 h. After cooling to room temperature, the graphene / PEDOT:PSS gel fiber was removed from the silicone tube. It was soaked in concentrated sulfuric acid to remove most of the PSS. Then it was washed with deionized water to obtain the graphene / PEDOT composite fiber prepared by the "assembly-deassembly-reassembly" method. (4) Preparation of the control group of composite fiber by "one-time co-assembly" method: 1 mL of 11 mg / mL graphene oxide solution and 1 mL of 11 mg / mL graphene oxide solution were mixed with 1 mL of 11 mg / mL graphene oxide solution. PEDOT:PSS was ultrasonically mixed for 30 min. 11.0 mg of ascorbic acid and 100.0 μL of 2.0 M sulfuric acid were added to 2.0 mL of the above mixture. The mixture was shaken vigorously for 2 min to gel. The subsequent processing was the same as in (3). Finally, graphene / PEDOT composite fiber prepared by the "one-time co-assembly" method was obtained. (5) The two ends of the washed fibers were fixed and dried at room temperature for 12 h. It can be used as the positive electrode of zinc ion capacitor fiber.

[0034] The microstructure of a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport prepared by the "assembly-deassembly-reassembly" method in (3) was characterized, and the results were as follows: Figure 1 and Figure 2 The scanning electron microscope images shown; composite fibers prepared by two different methods were used as the positive electrode, zinc wire as the negative electrode, and 2M zinc sulfate aqueous solution as the electrolyte. Electrochemical tests were performed in an electrolytic cell, yielding the following results: Figure 3 The figure shows a comparison of the volumetric specific capacity of the two composite fibers under different current densities.

[0035] A fully solid-state zinc-ion capacitor was assembled by arranging composite fibers and galvanized carbon fibers in parallel, and its electrochemical performance was tested to obtain the following results: Figure 4 The volumetric capacity diagrams shown are for different current densities, as follows: Figure 5 The CV plots at different scan rates are shown below. Figure 6 The GCD plots for different current densities are shown below. Figure 7 The EIS diagram shown is as follows: Figure 8 The Ragone diagram shown.

[0036] Example 2

[0037] (1) Preparation of graphene precursor: Graphene oxide precursor liquid was prepared by using 325 mesh graphite powder as raw material according to the modified Hummers method. (2) Preparation of graphene microgel particle suspension: 60 mL of 4 mg / mL graphene oxide precursor liquid was hydrothermally reacted at 160℃ for 16 h. After cooling, the reaction product was taken out and thoroughly washed with water to remove impurities. The reaction product was sonicated for 4 h to obtain graphene microgel particle suspension. (3) Preparation of composite fibers: 1 mL of 5.5 mg / mL graphene microgel particle suspension and 1 mL of 11 mg / mL PEDOT:PSS were ultrasonically mixed for 30 min. 150.0 μL of 1.0 M sulfuric acid was added to 2.0 mL of the above mixture. The mixture was shaken vigorously for 2 min to gel. The air bubbles were removed with a vacuum water pump. The gel mixture was injected into a silicone tube with a syringe. The mixture was subjected to hydrothermal reaction at 100 °C for 2 h. After cooling to room temperature, the graphene / PEDOT gel fiber was taken out of the silicone tube, soaked in ethylene glycol to remove most of the PSS, and then washed with deionized water to obtain the graphene / PEDOT composite fiber assembly. (4) The two ends of the washed fiber were fixed and dried at room temperature for 6 h. It can be used as the positive electrode of zinc ion capacitor fiber.

[0038] The microstructure of the graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport prepared above was characterized, and similar results were obtained. Figure 1 and Figure 2 The scanning electron microscope image shown depicts a fully solid-state zinc-ion capacitor assembled by parallel arrangement of composite fibers and galvanized carbon fibers, followed by electrochemical performance testing, yielding similar results. Figure 4 The volumetric specific capacity diagrams shown are similar to those for different current densities. Figure 5 The CV plots shown at different scan rates are similar to... Figure 6 The GCD plots shown are similar to those for different current densities. Figure 7 The EIS diagram shown is similar to Figure 8 The Ragone diagram shown.

[0039] Example 3

[0040] (1) Preparation of graphene precursor: Graphene oxide precursor liquid was prepared using 12000 mesh graphite powder as raw material according to the modified Hummers method. (2) Preparation of graphene microgel particle suspension: 100 mL of 3 mg / mL graphene oxide precursor liquid was hydrothermally reacted at 200℃ for 9 h. After cooling, the reaction product was taken out and thoroughly washed with water to remove impurities. The reaction product cells were crushed for 0.5 h to obtain graphene microgel particle suspension. (3) Preparation of composite fibers: 1 mL of 22 mg / mL graphene microgel particle suspension and 1 mL of 11 mg / mL PEDOT:PSS were ultrasonically mixed for 30 min. 200.0 μL of 2.0 M sulfuric acid was added to 2.0 mL of the above mixture. The mixture was shaken vigorously for 2 min to gel. The air bubbles were removed with a vacuum water pump. The gel mixture was injected into a silicone tube with a syringe. The mixture was subjected to hydrothermal reaction at 70 °C for 6 h. After cooling to room temperature, the graphene / PEDOT gel fiber was taken out of the silicone tube and soaked in tetrahydrofuran to remove most of the PSS. Then it was washed with deionized water to obtain the graphene / PEDOT composite fiber assembly. (4) The two ends of the washed fiber were fixed and dried at room temperature for 8 h. It can be used as the positive electrode of zinc ion capacitor fiber.

[0041] The microstructure of the graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport prepared above was characterized, and similar results were obtained. Figure 1 and Figure 2 The scanning electron microscope image shown depicts a fully solid-state zinc-ion capacitor assembled by parallel arrangement of composite fibers and galvanized carbon fibers, followed by electrochemical performance testing, yielding similar results. Figure 4 The volumetric specific capacity diagrams shown are similar to those for different current densities. Figure 5 The CV plots shown at different scan rates are similar to... Figure 6 The GCD plots shown are similar to those for different current densities. Figure 7 The EIS diagram shown is similar to Figure 8 The Ragone diagram shown.

Claims

1. A method for preparing graphene / PEDOT composite fibers with synergistic enhancement of electron / ion transport, characterized in that, It includes the following steps: (1) Preparation of graphene precursor: Using graphite powder as raw material, graphene oxide precursor solution was prepared according to the improved Hummers method; (2) Preparation of graphene gel microparticle suspension, i.e. assembly-disassembly: The graphene oxide precursor solution of a certain concentration in step (1) is subjected to hydrothermal reaction at a certain temperature for a period of time. After cooling, the reaction product is taken out and thoroughly washed with water to remove impurities, and graphene gel assembly is obtained. The obtained graphene gel is disassembled by stirring, sonication, ball milling or cell pulverization for a period of time, and graphene gel microparticle suspension is obtained accordingly. The hydrothermal reaction temperature was 140.0-200.0℃, the reaction time was 6.0-24.0 h, the magnetic stirring time was 0.5-72.0 h, the ultrasonic time was 0.5-5 h, the ball milling time was 0.5-5 h, and the cell disruption time was 0.1-1 h. (3) Preparation of composite fibers: Take the graphene gel microparticle suspension and poly(3,4-ethylenedioxythiophene): polystyrene sulfonic acid (PEDOT:PSS) from step (2), mix them evenly by ultrasonication, add an acidic solution, and gel the mixture by vigorous oscillation. Inject the gel mixture into a silicone tube with a syringe, and hydrothermally heat it at a certain temperature for a period of time. After cooling, take out the obtained gel fibers from the silicone tube and soak them in concentrated sulfuric acid or organic solvent for a certain time to remove a large amount of PSS, and obtain the graphene / PEDOT composite fibers prepared by the "assembly-disassembly-reassembly" method. (4) Washing: The graphene / PEDOT composite fiber obtained in step (3) is thoroughly washed with deionized water to remove impurities; (5) Drying: Fix both ends of the washed fiber and dry it thoroughly at room temperature. It can be used directly as an electrode material.

2. The method for preparing a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport according to claim 1, characterized in that, In step (1), the graphite powder is 12000-325 mesh, and the concentration of the graphene oxide precursor solution is 1-15 mg / mL.

3. The method for preparing a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport according to claim 2, characterized in that, The concentration of the graphene oxide precursor solution was 2.0-6.0 mg / mL.

4. The method for preparing a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport according to claim 1, characterized in that, Step (2) The concentration of graphene gel microparticle suspension is 5-30 mg / mL.

5. The method for preparing a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport according to claim 1, characterized in that, Step (3) The mass ratio of graphene gel microparticle suspension to PEDOT:PSS raw material is 1:20-20:

1.

6. The method for preparing a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport according to claim 5, characterized in that, The mass ratio of graphene gel microparticle suspension to PEDOT:PSS raw material is 1:2-2:

1.

7. A method for preparing a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport according to claim 1, characterized in that, In step (3), the acid in the acidic aqueous solution is one or more of sulfuric acid, hydrochloric acid, or hydroiodic acid, with a concentration of 0.01-5.0 M, a hydrothermal reaction temperature of 60.0-120.0 ℃, a reaction time of 1.0-8.0 h, and a soaking time of concentrated sulfuric acid or organic solvent of 3.0 h-48.0 h. The organic solvent refers to one or more of ethylene glycol, dimethyl sulfoxide, or tetrahydrofuran.

8. A method for preparing a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport according to claim 1, characterized in that, In step (5), washing refers to immersing the obtained graphene / PEDOT composite fiber in deionized water at room temperature; in step (6), drying refers to fixing both ends of the washed composite fiber and drying it at room temperature for 4-12 hours to obtain graphene / PEDOT composite fiber.

9. A method for preparing a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport according to claim 1, characterized in that, In step (2), during the hydrothermal process of graphene oxide, a doping source or other precursor is introduced to prepare doped graphene gel or graphene composite gel.

10. A graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport prepared according to any one of claims 1-9.

11. The application of a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport prepared according to any one of claims 1-9, as the positive electrode of a fibrous zinc ion capacitor.

12. The application of a graphene / PEDOT composite fiber with synergistic enhancement of electron / ion transport prepared according to any one of claims 1-9, wherein the graphene / PEDOT-based composite fiber electrode and galvanized carbon fiber are assembled into an all-solid-state fibrous zinc ion capacitor by winding or parallel arrangement.

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