Preparation method and application of amine functional modified multilevel porous fiber

Abstract

The invention belongs to the technical field of energy storage and new materials, and particularly relates to a preparation method and application of amine functional modified multilevel porous fibers. The method comprises the following steps: mixing a graphene oxide dispersion liquid, sodium polyacrylate, Triton X-100 and a solvent to obtain a spinning solution; the preparation method comprises the following steps: carrying out electrostatic spinning to obtain a graphene oxide nanofiber membrane, and winding the obtained graphene oxide nanofiber membrane by adopting a winding process to obtain a single hierarchical pore fiber yarn; s2, placing the single hierarchical pore fiber yarn obtained in S2 in an amine functional modification solution for surface functional group modification to obtain an ammonia functional modified special one-dimensional fiber electrode; and carrying out chemical reduction to obtain the amine functional modified multistage porous fiber. According to the preparation method, the hierarchical pore one-dimensional fiber with layered winding hierarchical pore structure characteristics and positive charges on the surface is obtained, and the hierarchical pore one-dimensional fiber has good electrochemical characteristics in a zinc-iodine battery and is suitable for large-scale batch production.

Description

Technical Field

[0001] The present invention belongs to the technical fields of energy storage and new materials, and particularly relates to a preparation method and application of amine-functionalized modified hierarchical porous fibers. Background Art

[0002] Aqueous zinc-based batteries are considered to be one of the most promising candidates due to their high theoretical capacity, low electrode potential (-0.763V vs SHE), and good stability in air. In the past few decades, batteries such as zinc-manganese oxide, zinc-vanadium oxide, zinc-prussian blue analogues, zinc-air, and zinc-halogen atoms have been successfully developed. Among them, different from the energy storage method of traditional zinc-based batteries that stores capacity through the insertion and extraction of Zn2+, the aqueous zinc-iodine battery based on the redox reaction of iodine at the cathode and the deposition / stripping of zinc at the anode for capacity storage not only can generate a high theoretical capacity of 211 mAh g -1 . More importantly, iodine has multiple valence states (such as -1, 0, +1, +3, +5, and +7), which theoretically endows it with great potential for multi-electron conversion. Although the aqueous zinc-iodine battery has broad prospects, there are still some problems that need to be urgently solved at the present stage. For example, the electronic insulation of I 2 will increase the polarization of the battery; the limited content of active materials is not conducive to achieving a high energy density of the battery; and during the charge and discharge process, insoluble I 2 on the cathode side can spontaneously combine with I － to form highly soluble polyiodides. Due to this concentration gradient ("shuttle effect"), polyiodide ions tend to shuttle through the separator to the anode side. The direct result of this phenomenon is the corrosion of the zinc anode, because polyiodide ions can react with zinc metal (Zn + I 3 - → Zn 2+ + 3I - + Heat). In addition, the electron transfer of this reaction does not pass through the external circuit, which will lead to serious self-discharge behavior, thereby reducing the Coulombic efficiency of the Zn-I 2 battery.

[0003] Currently, a variety of strategies have been developed to inhibit the shuttle of polyiodides. (1) Porous carbon materials. In 2018, the confinement effect of porous carbon cathodes on iodine species was proposed through DFT calculations and experimental measurements, indicating that porous carbon materials can confine I 2 within their microporous structures to inhibit excess I 3 -Formation. This theory has also been further confirmed in subsequent studies. However, it is difficult to completely restrict the dissolution of iodine substances in the electrolyte solely relying on the weak physical adsorption of porous carbon. Therefore, researchers have designed functional iodine host materials to enhance the restriction of iodine species. For example, Prussian blue analogues and MXene, etc. The prior art uses I-terminated halogenated Ti 3 C 2 I 2 The etched MXene presents a typical accordion shape, which can not only effectively restrict iodine species, but also accelerate the conversion kinetics of iodine, thereby improving the performance of Zn-I 2 battery. In addition to the structural regulation and functional modification of the cathode material, some researchers use the water-in-salt (WIS) electrolyte strategy to aggregate the diffusion of polyiodide ions. The prior art effectively inhibits the dissolution of I 2 and the diffusion of I 3 - by using a concentrated zinc chloride / potassium iodide electrolyte, significantly inhibits the shuttle effect of polyiodides, and improves the Coulomb efficiency. However, the high viscosity and slow ion transport characteristics of the WIS electrolyte seriously damage the battery performance, and the use of a large amount of salt will increase the cost of the battery. Nevertheless, there is still a large gap between expectation and reality, and the development of more advanced materials for restricting iodine species remains to be explored. Summary of the Invention

[0004] Aiming at the problem in the prior art that the shuttle effect caused by the dissolution of polyiodides during the zinc-iodine battery test leads to battery performance degradation, the present invention provides a preparation method of amine-functionalized modified multi-stage porous fibers, including the following steps:

[0005] S1: Mix the graphene oxide dispersion, sodium polyacrylate, Triton X-100 and a solvent in a mass ratio of 5:2:1:2 to obtain a spinning solution;

[0006] S2: Electrospinning to obtain a graphene oxide nanofiber membrane, and winding the obtained graphene oxide nanofiber membrane by a winding process to obtain a single multi-stage pore fiber filament;

[0007] S3: Place the single multi-stage pore fiber filament obtained in S2 in an amine-functionalized modification solution for surface functional group modification to obtain a special one-dimensional fiber electrode with ammonia-functionalized modification; then perform chemical reduction to obtain amine-functionalized modified multi-stage porous fibers.

[0008] Further, the solvent described in S1 is deionized water, the concentration of the graphene oxide dispersion in S1 is 20-25 mg / ml, and the concentration of sodium polyacrylate is 2 wt%.

[0009] Further, the parameters in the electrospinning in S2 include a positive high voltage of 30 - 35 KV; a pushing speed of the spinning solution of 0.2 - 0.3 ml / min; and a temperature of 60 - 80 °C.

[0010] Further, the amine-functionalized multi-stage porous fiber in S2 has a layered structure.

[0011] Further, the amine-functionalized modification solution in S3 is a mixed solution including EDC and EDA solutions, deionized water, and ethanol.

[0012] Further, the temperature in the reduction process in S3 is 90 °C, and the reduction time is 12 h.

[0013] Further, the specially one-dimensional fiber electrode with amine-functionalized modification in S3 has a layered multi-stage pore structure and a positive charge characteristic.

[0014] An amine-functionalized multi-stage porous fiber, and the amine-functionalized multi-stage porous fiber has a layered wound porous structure.

[0015] An application of an amine-functionalized multi-stage porous fiber, and the amine-functionalized multi-stage porous fiber is applied in the preparation of an electrode material.

[0016] Beneficial effects

[0017] The present invention provides a preparation method of an electrode material of an amine-functionalized multi-stage porous fiber. This preparation method uses a graphene oxide dispersion liquid as a raw material, and adopts a method of combining electrospinning and winding processes to form a novel layered wound porous fiber structure. On this basis, the surface functional groups of the fiber are combined with amine-functionalized modification, and a one-dimensional fiber electrode material with a special layered porous structure and a multi-stage porous fiber with a positive charge on the surface are successfully prepared. The preparation method provided by the present invention has a novel preparation method and simple operation. The prepared fiber not only has excellent mechanical properties and good electrochemical characteristics in a zinc-iodine battery. Its layered porous structure is not only beneficial to the adsorption of iodine, and the layered wound structure can well limit the shuttle of polyiodide ions. At the same time, the surface positive charge functionalization modification enhances the adsorption of iodine (iodine molecules, iodide ions, and polyiodide ions). At the same time, the production environment requirements of this method are low, and it is suitable for large-scale batch production. The present invention also provides an application of the amine-functionalized multi-stage porous fiber as an electrode material in an aqueous zinc-iodine battery, which shows an ultra-high capacity storage ability. And the material has good bendability and will have great potential in the fields of energy, new materials, and flexible electronics. At the same time, due to its one-dimensional fiber characteristics, it also has a wide application in flexible one-dimensional iodide ion batteries. Description of the drawings

[0018] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings required for 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 limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings. In the drawings:

[0019] Figure 1 SEM surface view of the multi - level porous fiber electrode material of Example 1 of the present invention;

[0020] Figure 2 SEM cross - sectional view of the multi - level porous fiber electrode material of Example 1 of the present invention;

[0021] Figure 3 Galvanostatic charge - discharge curve of the multi - level porous fiber electrode material of Example 1 of the present invention in a zinc - iodine battery at a current density of 0.5 A g -1 ;

[0022] Figure 4 Galvanostatic charge - discharge curve of the multi - level porous fiber electrode material with amine functionalization modification for 2 hours in Example 2 of the present invention in a zinc - iodine battery at a current density of 0.5 A g -1 ;

[0023] Figure 5 Galvanostatic charge - discharge curve of the multi - level porous fiber electrode material with amine functionalization modification for 4 hours in Example 3 of the present invention in a zinc - iodine battery at a current density of 0.5 A g -1 ;

[0024] Figure 6 SEM surface view of the multi - level porous fiber electrode material with amine functionalization modification for 6 hours in Example 4 of the present invention;

[0025] Figure 7 SEM cross - sectional view of the multi - level porous fiber electrode material with amine functionalization modification for 6 hours in Example 4 of the present invention;

[0026] Figure 8 Galvanostatic charge - discharge curve of the multi - level porous fiber electrode material with amine functionalization modification for 6 hours in Example 4 of the present invention in a zinc - iodine battery at a current density of 0.5 A g -1 ;

[0027] Figure 9 Bar chart of the proportion of pseudocapacitance of the multi - level porous fiber electrode material with amine functionalization modification for 6 hours in Example 4 of the present invention in a zinc - iodine battery at different scanning rates;

[0028] Figure 10Long cycle test chart of the amine-functionalized and modified multi-stage porous fiber electrode material for 6 hours in Example 4 of the present invention at a current density of 2 A g-1 in a zinc-iodine battery;

[0029] Figure 11 Flow chart of the amino modification of graphene fiber of the present invention. Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely in conjunction with Embodiments 1 to 4 of the present invention and the attached Figures 1 to 11 , the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] Embodiment 1

[0032] S1: Mix the graphene oxide dispersion, deionized water, sodium polyacrylate (PAAS), and Triton X-100 to obtain a spinning solution. Among them, the concentration of the graphene oxide dispersion is 20 mg / ml; the concentration of sodium polyacrylate is 2 wt%, and the mass ratio of GO:PAAS:X100:solvent is 5:2:1:2;

[0033] S2: Prepare a graphene oxide nanofiber membrane by electrospinning technology under the conditions of a positive high voltage of 30 KV, a spinning solution injection speed of 0.2 ml / min, and a temperature of 60 °C; use a winding process to wind the obtained nanofiber membrane to obtain a single fiber filament (GF) with the characteristics of a nanofiber membrane;

[0034] S3: Chemically reduce the GF fiber in hydroiodic acid at a reduction temperature of 90 °C and a reduction time of 12 h. This material is named rGF.

[0035] Assemble the electrolytic cell type zinc-iodine battery with the material obtained in Embodiment 1: use the rGF fiber with a length of 1.2 cm as the positive electrode material, the polished zinc sheet as the negative electrode, and 10 M ZnCl 2 Add 2.5 M KI as the electrolyte.

[0036] Use the assembled battery in a two-electrode system on an electrochemical workstation (CHI760E in China) to perform constant current charge and discharge tests at room temperature. The test voltage range is 0.4 - 1.6 V, and the current density is 0.5 A g -1 .

[0037] The surface morphology of the prepared multi-stage porous fiber is as Figure 1As shown, obvious winding marks can be seen on the fiber surface, and there are certain nanofiber membrane characteristics. This characteristic is beneficial to the adsorption of polyiodide by the fiber electrode in the zinc-iodine battery system, thereby alleviating the shuttling effect of polyiodide. The cross-section of the rGF fiber is as Figure 2 shown. From the figure, the winding marks of the fiber can be seen more clearly. Due to this winding process, a hierarchical porous structure exists inside the fiber, and this structure will limit the polyiodide layer by layer to alleviate its shuttling effect.

[0038] The battery test results are as Figure 3 shown. It can be seen that at a current density of 0.5Ag -1 , the discharge specific capacity of the rGF fiber electrode is 151 mAh g -1 , and the voltage polarization is 0.223V.

[0039] Example 2

[0040] S1: Mix graphene oxide dispersion, deionized water, sodium polyacrylate (PAAS), and Triton X-100 to obtain a spinning solution. Among them, the concentration of the graphene oxide dispersion is 25 mg / ml; the concentration of sodium polyacrylate is 2 wt%, and the mass ratio of GO:PAAS:X100:solvent is 5:2:1:2;

[0041] S2: Prepare a graphene oxide nanofiber membrane by electrospinning technology under the conditions of a positive high voltage of 35 KV, a spinning solution injection speed of 0.3 ml / min, and a temperature of 80 °C; use a winding process to wind the obtained nanofiber membrane to obtain a single fiber filament (GF) with nanofiber membrane characteristics;

[0042] S3: Immerse the GF fiber in an amine-functionalized modification solution composed of a mixed solution of 0.3 g EDC plus 3 ml EDA solution dissolved in 15 ml deionized water plus 15 ml ethanol for 2 h for surface functional group modification to obtain NGF-2 fiber

[0043] S4. Immerse the NGF-2 fiber in hydroiodic acid for chemical reduction. The reduction temperature is 90 °C and the reduction time is 12 h. This material is named rNGF-2.

[0044] Assemble an electrolytic cell type zinc-iodine battery with the material obtained in Example 2: Use an rNGF-2 fiber with a length of 1.2 cm as the positive electrode material, a polished zinc sheet as the negative electrode, and 10M ZnCl 2 plus 2.5M KI as the electrolyte.

[0045] The assembled battery was tested for constant current charge and discharge at room temperature using a two - electrode system on an electrochemical workstation (CHI760E, China). The test voltage range was 0.4 - 1.6 V, and the current density was 0.5 A g -1 .

[0046] The battery test results are as Figure 4 shown. It can be seen that at a current density of 0.5 A g -1 , the discharge specific capacity of the rNGF - 2 fiber electrode was 150 mAh g -1 , and the voltage polarization was 0.15 V.

[0047] Example 3

[0048] S1: Graphene oxide dispersion, deionized water, sodium polyacrylate (PAAS), and Triton X - 100 were mixed to obtain a spinning solution. Among them, the concentration of the graphene oxide dispersion was 22.5 mg / ml; the concentration of sodium polyacrylate was 2 wt%, and the mass ratio of GO:PAAS:X100:solvent was 5:2:1:2;

[0049] S2: Through electrospinning technology, a graphene oxide nanofiber membrane was prepared under the conditions of a positive high voltage of 32.5 KV, a spinning solution injection speed of 0.2 ml / min, and a temperature of 70 °C; the obtained nanofiber membrane was wound using a winding process to obtain a single fiber filament (GF) with the characteristics of a nanofiber membrane;

[0050] S3: The GF fiber was placed in an amine - functionalized modification solution composed of a mixed solution of 0.3 g EDC plus 3 ml EDA solution dissolved in 15 ml deionized water plus 15 ml ethanol for 4 h for surface functional group modification to obtain NGF - 4 fiber.

[0051] S4: The NGF - 4 fiber was chemically reduced in hydroiodic acid. The reduction temperature was 90 °C, and the reduction time was 12 h. This material was named rNGF - 4.

[0052] The material obtained in Example 3 was assembled into an electrolytic cell - type zinc - iodine battery: using an rNGF - 4 fiber with a length of 1.2 cm as the positive electrode material, a polished zinc sheet as the negative electrode, and 10 M ZnCl 2 plus 2.5 M KI as the electrolyte.

[0053] The assembled battery was tested for constant current charge and discharge at room temperature using a two - electrode system on an electrochemical workstation (CHI760E, China). The test voltage range was 0.4 - 1.6 V, and the current density was 0.5 A g -1 .

[0054] The battery test results are as Figure 5As shown, it can be seen that at a current density of 0.5 Ag -1 , the discharge specific capacity of the rNGF-4 fiber electrode is 176 mAh g -1 , and the voltage polarization is 0.19 V.

[0055] Example 4

[0056] S1: Mix graphene oxide dispersion, deionized water, sodium polyacrylate (PAAS), and Triton X-100 to obtain a spinning solution. Among them, the concentration of the graphene oxide dispersion is 22.5 mg / ml; the concentration of sodium polyacrylate is 2 wt%, and the mass ratio of GO:PAAS:X100:solvent is 5:2:1:2;

[0057] S2: Prepare a graphene oxide nanofiber membrane by electrospinning technology under the conditions of a positive high voltage of 30 KV, a spinning solution injection speed of 0.2 ml / min, and a temperature of 60 °C; use a winding process to wind the obtained nanofiber membrane to obtain a single fiber filament (GF) with the characteristics of a nanofiber membrane;

[0058] S3: Place the single fiber filament (GF) obtained in S2 in an amine-functionalized modification solution composed of a mixed solution of 0.3 g EDC plus 3 ml EDA solution dissolved in 15 ml deionized water plus 15 ml ethanol for 6 h for surface functional group modification to obtain NGF-6 fibers.

[0059] S4. Place the NGF-6 fibers in hydroiodic acid for chemical reduction. The reduction temperature is 90 °C and the reduction time is 12 h. This material is named rNGF-6.

[0060] Assemble an electrolytic cell type zinc-iodine battery with the material obtained in Example 4: Use the rNGF-6 fiber with a length of 1.2 cm as the positive electrode material, and the polished zinc sheet as the negative electrode. 10 M ZnCl 2 plus 2.5 M KI as the electrolyte.

[0061] Use a two-electrode system to perform constant current charge and discharge tests on the assembled battery at room temperature on an electrochemical workstation (CHI760E, China). The test voltage range is 0.4 - 1.6 V, and the current density is 0.5 Ag -1 . In the voltage range of 0.4 - 1.6 V, perform cyclic voltammetry tests at different scan rates (0.6 - 1.6 mV s -1 ), with 3 cycles, to calculate the proportion of the pseudocapacitance contribution of the rNGF-6 fiber electrode in the zinc-iodine battery. The voltage range of the long cycle test is also 0.4 - 1.6 V, and the current density is 2 Ag -1 .

[0062] The surface morphology of the prepared rNGF-6 fibers is asFigure 6 As shown in Figure 1. Even after amine functionalization, the fiber surface still retains the characteristics of electrospun nanofiber membranes, with more pore structures, which is no different from the surface of rGF fibers in Example 1. The cross-section of the multi-level porous fiber modified with amine functionalization for 6 hours is shown in Figure 1. Figure 7 As shown, from the cross-sectional view we can clearly see that the fiber is in a hollow state. This is because during the modification process of the hydrophilic GF fiber, the water in the solution causes the fiber to expand in volume through capillary action and osmosis, resulting in the detachment of some loosely wound fibers, and finally presenting this state, which will increase the contact area between the rNGF-6 fiber electrode and the electrolyte to a certain extent.

[0063] Battery at 0.5Ag -1 The constant current charge and discharge curve under current density is as follows Figure 8 The discharge capacity of the rNGF-6 fiber electrode is 321 mAh g -1 , the voltage polarization is 0.069V. Figure 9 The CV graphs of rNGF-6 fiber electrodes were obtained by testing at different scanning rates, and the pseudocapacitance contribution bar graphs were obtained based on the corresponding calculations. It can be seen that even at 0.6 mVs -1 At a low scan rate of , there is still a 58.72% pseudocapacitance share, indicating that capacitive behavior plays an important role in the dynamics. Figure 10 For rNGF-6 fiber electrodes in 2Ag -1 From the long cycle test chart under the current density of , it can be seen that after 19,000 cycles, there is still a capacity retention rate of 93.5%, and the average coulombic efficiency reaches 99%.

[0064] In summary, by comparing the electrochemical data of four different fibers, rGF, rNGF-2, rNGF-4 and rNGF-6, prepared in Examples 1-4, it can be seen that as the amine functionalization time increases, the polarization voltage of the fiber electrode during the electrochemical test decreases, and the capacity is further improved. This is because more amine functionalization modification time causes the fiber to carry more positively charged amino groups, which is conducive to improving the adsorption of polyiodide by the fiber electrode.

[0065] Through a preparation method of an amine-functionalized modified multi-stage porous fiber provided by the present invention, in the electrode material provided by the present invention, the innovation of the material brings good technical effects. By designing the pore structure of the material, while retaining the bendability of the fiber, surface functional group modification is carried out to enhance the adsorption of the electrode to polyiodide and catalyze the conversion reaction between iodine species through the synergistic effect of physical and chemistry, thereby improving the electrochemical performance. By comparing the differences in the mechanical properties and electrochemical properties of the fiber with different amine-functionalized modification times, the electrode material most suitable for zinc-iodine batteries is screened out. The preparation process of this material is simple and will have great potential in the fields of energy and new materials as well as flexible electronic devices.

Claims

1. A method for preparing a multi-level porous fiber modified by amine functionalization, characterized in that: The following steps are involved: S1: mixing graphene oxide dispersion, sodium polyacrylate, Triton X-100 and solvent in a mass ratio of 5:2:1:2 to obtain a spinning solution; S2: obtaining a graphene oxide nanofiber membrane by electrospinning, and winding the obtained graphene oxide nanofiber membrane by a winding process to obtain a single multi-level porous fiber; S3: placing the single multi-level porous fiber obtained in S2 in an amine functional modification solution for surface functional group modification to obtain a special one-dimensional fiber electrode modified with amine functionalization; and then chemically reducing it to obtain a multi-level porous fiber modified with amine functionalization.

2. The method for preparing an amine-functionalized multi-level porous fiber according to claim 1, characterized in that: The solvent described in S1 is deionized water, the concentration of the graphene oxide dispersion in S1 is 20-25 mg / ml, and the concentration of sodium polyacrylate is 2 wt %.

3. The method for preparing an amine-functionalized multi-level porous fiber according to claim 1, characterized in that: The parameters of the electrospinning in S2 include a positive high voltage of 30-35 KV; a spinning solution injection speed of 0.15-0.3 ml / min; and a temperature of 60-80°C.

4. The method for preparing an amine-functionalized multi-level porous fiber according to claim 1, characterized in that: The amine-functionalized hierarchical porous fibers in S2 have a layered structure.

5. The method for preparing an amine-functionalized multi-level porous fiber according to claim 1, characterized in that: The amine functional modification solution described in S3 is a mixed solution including EDC and EDA solutions and deionized water and ethanol.

6. The method for preparing an amine-functionalized multi-level porous fiber according to claim 1, characterized in that: The temperature during the reduction process described in S3 is 90° C. and the reduction time is 12 h.

7. The method for preparing an amine-functionalized multi-level porous fiber according to claim 1, characterized in that: The special one-dimensional fiber electrode modified with amino functionalization described in S3 has a layered multi-level pore structure and has positive electrical properties.

8. An amine-functionalized multi-level porous fiber obtained by the preparation method according to any one of claims 1 to 7, characterized in that: The amine-functionalized multi-level porous fiber is a layered winding porous structure.

9. The use of an amine-functionalized multi-level porous fiber according to claim 8, characterized in that: The amine functionalized multi-level porous fiber is used in the preparation of electrode materials.

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