Ultra-microporous carbon nanosphere of semi-anchored polymeric ionic liquid as well as preparation method and application of ultra-microporous carbon nanosphere

Abstract

The invention relates to ultra-microporous carbon nanospheres of semi-anchored polymeric ionic liquid as well as a preparation method and application of the ultra-microporous carbon nanospheres. The ultra-microporous carbon nanospheres of the polymeric ionic liquid are prepared through a semi-anchoring strategy; adding a water-soluble initiator into the emulsified reaction monomer acrylonitrile, initiating a polymerization reaction to obtain a polymerization product, and pre-oxidizing and carbonizing the polymerization product to obtain ultra-microporous carbon nanospheres; the preparation method comprises the following steps: mixing ultramicropore carbon nanospheres with ionic liquid 1-vinyl-3-ethylimidazolium bromide, and grafting the 1-vinyl-3-ethylimidazolium bromide to the surfaces of the polyacrylonitrile-based ultramicropore carbon nanospheres under the action of an oil-soluble initiator; the constructed ultra-microporous carbon nanospheres of the semi-anchored polymeric ionic liquid with both ion selectivity and seepage network continuity can be applied to Na < + > recovery of a saline system, and shows high adsorption rate and excellent separation performance; the preparation method is simple to operate and environment-friendly, and a new example is provided for high-efficiency desalination of seawater.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of supercapacitor deionization, and particularly relates to a semi-anchored polymeric ionic liquid super-microporous carbon nanosphere and a preparation method and application thereof. BACKGROUND

[0002] Freshwater scarcity is one of the most severe global challenges in the contemporary era, and seawater / saline water desalination is increasingly considered as a practical solution to meet domestic and municipal water demand. Among various seawater desalination technologies, capacitive deionization (CDI) is a promising method, which requires lower operating voltage and energy consumption compared to traditional technologies such as reverse osmosis, multi-effect distillation, and multi-stage flash evaporation. In particular, flow-electrode capacitive deionization (FCDI), which has evolved from CDI, has become a promising candidate for seawater desalination due to its unique ability to achieve continuous desalination and regeneration.

[0003] Electrode materials are the key to determining the performance of flow-electrode capacitive deionization. Although Faradaic materials (such as Mxene and MOFs) have also been reported, carbon-based materials, due to their excellent electrochemical stability and good electrical conductivity, can ensure continuous and stable operation, and become one of the most promising electrode candidates for seawater desalination. However, a common challenge for flow-electrode capacitive deionization seawater desalination is the discontinuity of electron transport, which is mainly due to the discontinuity of the charge percolation network. Although increasing the carbon content helps to establish a conductive network, the significant increase in slurry viscosity will lead to channel blockage and require higher pumping power, ultimately reducing the performance of flow-electrode capacitive deionization seawater desalination. Therefore, simply increasing the solid content cannot solve the "trade-off" problem between rheological properties and charge percolation networks. According to percolation theory, when the mass fraction of active material increases to a certain critical value, i.e., the charge percolation threshold. At this time, a continuous charge percolation network is formed, and charges can be transmitted between particles through these networks. That is, as long as the charge percolation threshold is reduced, it is possible to build a percolation network at a low mass load without significantly increasing the viscosity. Therefore, how to build a percolation network is the key to solving the common problem of charge discontinuity.

[0004] The interference of multivalent ions reduces the desalination efficiency, which is the main problem faced by carbon-based electrode materials. Since carbon-based materials themselves lack ion selectivity, the stronger Coulombic interaction is conducive to the adsorption of multivalent ions rather than monovalent ions. Worse still, the irreversible adsorption of multivalent ions reduces the available adsorption sites, thereby greatly reducing the seawater desalination capacity. In order to solve this problem, existing literature reports mainly focus on the "super-micropore confinement effect" strategy. When the pore size is less than 0.7 nm, hydrated Na + (hydrated radius rh=0.358 nm) can pass directly, while hydrated Mg 2+(rh=0.428 nm) must overcome the dehydration energy barrier to pass through. Although the above super-micropore confinement effect can achieve selective separation of ions, it is technically difficult to consider constructing a percolation network on the surface of the super-micropore without blocking the super-micropore structure. Therefore, how to accurately regulate the charge percolation network and improve ion selectivity is the key to optimizing the performance of the flow electrode capacitive deionization. SUMMARY

[0005] To solve the problem that the existing charge percolation network of carbon-based materials is discontinuous, resulting in discontinuous electron transmission, and the existing carbon-based electrode materials are interfered by multivalent ions, thereby reducing desalination efficiency, the application provides a semi-anchored polymeric ionic liquid super-microporous carbon nanosphere and a preparation method and application thereof.

[0006] The technical scheme adopted by the application is as follows:

[0007] A semi-anchored polymeric ionic liquid super-microporous carbon nanosphere preparation method, a water-soluble initiator is added to emulsified reaction monomer acrylonitrile, and a product obtained through polymerization is sequentially oxidized and carbonized to obtain a super-microporous carbon nanosphere; under the action of an oil-soluble initiator, an ionic liquid is introduced to the surface of the polyacrylonitrile-based super-microporous carbon nanosphere to obtain a semi-anchored polymeric ionic liquid super-microporous carbon nanosphere.

[0008] Preferably, the ionic liquid is one of 1-vinyl-3-ethyl imidazole bromide, 1-vinyl-3-cyanethyl imidazole bromide, 1-vinyl-3-sulfopropyl imidazole bromide and 1-vinyl-3-aminopropyl imidazole bromide;

[0009] Preferably, the water-soluble initiator is potassium persulfate;

[0010] The oil-soluble initiator is azobisisobutyronitrile.

[0011] Preferably, the specific steps are as follows:

[0012] Step one: dissolve an emulsifier and reaction monomer acrylonitrile in water, and emulsify under ultrasonic at 30-50 DEG C;

[0013] Step two: add a water-soluble initiator to the emulsified solution, and stir the obtained polymerization product at 60-80 DEG C;

[0014] Step three: pre-oxidize the polymerization product at 250 DEG C in an air atmosphere for 1-3 h; and then carbonize the product at 750-1050 DEG C in a nitrogen atmosphere for 1-3 h to obtain a polyacrylonitrile-based super-microporous carbon nanosphere;

[0015] Step four: add the polyacrylonitrile-based super-microporous carbon nanosphere and the ionic liquid to a solvent;

[0016] Step five: the mixed solution is placed in a nitrogen environment, and the oil-soluble initiator is added in an amount of 0.02-0.2% of the mass of the monomer, and the reaction is carried out under stirring at 60-80 DEG C to obtain the product;

[0017] Step six: the solid product is dispersed in anhydrous ethanol, and a mixed solution of anhydrous acetic acid sodium with a mass fraction of 20% and anhydrous ethanol is slowly added dropwise, and the reaction is carried out at 60-80 DEG C to obtain the semi-anchored polymer ionic liquid super-microporous carbon nanospheres.

[0018] Preferably, the mass ratio of the emulsifier, the reaction monomer and the water-soluble initiator is 1:40:0.12.

[0019] Preferably, the molar ratio of the polyacrylonitrile-based super-microporous carbon nanospheres to the ionic liquid is 3:1.

[0020] The semi-anchored polymer ionic liquid super-microporous carbon nanospheres are prepared by the method.

[0021] An electrode comprising semi-anchored polymer ionic liquid super-microporous carbon nanospheres.

[0022] Preferably, the semi-anchored polymer ionic liquid super-microporous carbon nanospheres, acetylene black and polyvinylidene fluoride are added to N-methyl pyrrolidone in a mass ratio of 8:1:1 to form a uniform electrode slurry, which is applied to the pole piece and dried to obtain the electrode.

[0023] A flow electrode capacitive deionization device comprising an electrode comprising semi-anchored polymer ionic liquid super-microporous carbon nanospheres.

[0024] A seawater desalination system for producing fresh water, comprising an electrode comprising semi-anchored polymer ionic liquid super-microporous carbon nanospheres.

[0025] The present application has the advantages and positive effects that:

[0026] The existing carbon-based material charge percolation network is discontinuous, and the irreversible adsorption of multivalent ions reduces the available adsorption sites, resulting in a decrease in desalination efficiency. By precisely adjusting the size and pore size of the polyacrylonitrile-based super-microporous carbon nanospheres to reduce the percolation threshold and improve the electrical conductivity, the ionic liquid 1-vinyl-3-ethyl imidazole bromide is "semi-anchored" grafted onto the surface of the polyacrylonitrile-based super-microporous carbon nanospheres to form a structured interface network, and a more continuous and efficient charge percolation network is constructed.

[0027] The application designs the super-microporous carbon nanospheres with unique structure of semi-anchored polymeric ionic liquid for the first time by the "semi-anchored" strategy to precisely regulate the grafting density of polyacrylonitrile-based super-microporous carbon nanospheres and 1-vinyl-3-ethylimidazole bromide, the cations of 1-vinyl-3-ethylimidazole bromide are polymerized on the surface of the carbon nanospheres, and the anions have a certain dynamic migration ability, which enhances the wettability of the material, reduces the formation of non-contact areas, and constructs a more continuous and efficient charge seepage network.

[0028] The prepared semi-anchored polymeric ionic liquid super-microporous carbon nanospheres are used as electrode materials for flow electrode capacitive deionization of Na + The application has excellent ion selectivity, and the preparation method has the characteristics of simple operation. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The implementation flowchart of the preparation method of the semi-anchored polymeric ionic liquid super-microporous carbon nanospheres;

[0030] Figure 2 The desalination mechanism diagram of the super-microporous carbon nanospheres in FCDI;

[0031] Figure 3 Characterization of semi-anchored polymeric ionic liquid super-microporous carbon nanospheres; a is a SEM graph (inset: particle size distribution graph); b-c are TEM graphs;

[0032] Figure 4 Pore size analysis of polyacrylonitrile-based super-microporous carbon nanospheres and semi-anchored polymeric ionic liquid super-microporous carbon nanospheres; a: CO2 adsorption-desorption isotherm; b: pore size distribution curve;

[0033] Figure 5 Water contact angle test of polyacrylonitrile-based super-microporous carbon nanospheres and semi-anchored polymeric ionic liquid super-microporous carbon nanospheres; a: water contact angle test of polyacrylonitrile-based super-microporous carbon nanospheres; b: water contact angle test of semi-anchored polymeric ionic liquid super-microporous carbon nanospheres;

[0034] Figure 6 Electrochemical cycle diagram. DETAILED DESCRIPTION

[0035] The embodiments of the application will be described below with reference to the accompanying drawings.

[0036] The application relates to a semi-anchored polymeric ionic liquid super-microporous carbon nanosphere and a preparation method and application thereof, and the semi-anchored polymeric ionic liquid super-microporous carbon nanosphere is prepared through a semi-anchored strategy. A water-soluble initiator is added into emulsified reaction monomer acrylonitrile to initiate a polymerization reaction to obtain a polymerization product, the polymerization product is pre-oxidized and carbonized to obtain the super-microporous carbon nanosphere, the super-microporous carbon nanosphere is mixed with ionic liquid, under the action of an oil-soluble initiator, the ionic liquid is grafted to the surface of the polyacrylonitrile-based super-microporous carbon nanosphere, and the semi-anchored polymeric ionic liquid super-microporous carbon nanosphere with a structured interface network structure is prepared.

[0037] The ionic liquid can be one of 1-vinyl-3-ethyl imidazole bromide, 1-vinyl-3-cyanethyl imidazole bromide, 1-vinyl-3-sulfopropyl imidazole bromide and 1-vinyl-3-aminopropyl imidazole bromide.

[0038] The implementation flowchart of the preparation method of the semi-anchored polymeric ionic liquid super-microporous carbon nanosphere is shown in the figure. Figure 1 The specific preparation method is as follows.

[0039] Step one: the emulsifier sodium hexadecyl diphenyl ether sulfonate and the reaction monomer acrylonitrile are dissolved in water, and are ultrasonically emulsified at 30-50 DEG C;

[0040] Step two: nitrogen gas is bubbled into the emulsified solution for 30 min, a water-soluble initiator potassium persulfate is added, the reaction system is stirred at 60-80 DEG C, the obtained polymerization product is white, and the product is extracted, washed and dried;

[0041] The mass ratio of the emulsifier, the reaction monomer and the water-soluble initiator is 1:40:0.12.

[0042] Step three: the polymerization product is transferred into a tubular furnace for pre-oxidation, the pre-oxidation condition is that the pre-oxidation is carried out at 250 DEG C at an air atmosphere and at a temperature increasing rate of 0.5 DEG C / min -1 for 1-3 h; then carbonization is carried out at a nitrogen atmosphere and at a temperature increasing rate of 2 DEG C / min -1 for 1-3 h at 750-1050 DEG C, and the polyacrylonitrile-based super-microporous carbon nanosphere is obtained;

[0043] Step four: the polyacrylonitrile-based super-microporous carbon nanosphere and the ionic liquid are added into chloroform and are ultrasonically dispersed; the molar ratio of the polyacrylonitrile-based super-microporous carbon nanosphere and the ionic liquid is 3:1.

[0044] Step five: the mixed solution is transferred into a Schlenk tube, nitrogen gas is passed for 30 min, the added oil-soluble initiator azobisisobutyronitrile accounts for 0.02-0.2% of the mass of the monomer, the stirring reaction is carried out at 60-80 DEG C for 3 h, the product is extracted, washed and dried, and the solid product is obtained.

[0045] Step six: disperse the solid product in anhydrous ethanol, slowly drop the mixture solution of anhydrous acetic acid sodium and anhydrous ethanol with mass fraction of 20%, then ion exchange reaction for 24h at 60℃ to obtain the final semi-anchored polymeric ionic liquid super-microporous carbon nanospheres.

[0046] The semi-anchored polymeric ionic liquid super-microporous carbon nanospheres prepared by the "semi-anchored strategy" have a spherical structure, good dispersibility, can reduce the agglomeration between particles, form a continuous charge seepage network, promote charge transfer, and can effectively remove the interference of multivalent ions through the comprehensive effect of different ion electrostatic attraction, solubility and migration barrier. The prepared semi-anchored polymeric ionic liquid super-microporous carbon nanospheres achieve excellent ion selectivity of the current flow electrode capacitive deionization, and its operation is simple and easy to mass production. The semi-anchored polymeric ionic liquid super-microporous carbon nanospheres retain the super-microporous framework, introduce additional micropores, construct a charge seepage network, improve charge transport, and greatly improve surface wettability.

[0047] In the prior art, although increasing carbon content helps to establish a conductive network, the significant increase in slurry viscosity can cause channel blockage and require higher pumping power, ultimately reducing the performance of flow electrode capacitive deionization seawater desalination. How to build a seepage network is the key to solving the problem of charge discontinuity. In addition, although the super-microporous confinement effect can achieve selective separation of ions, it is technically difficult to consider constructing a seepage network on the surface of super-micropores without blocking the super-microporous structure. By reducing the particle size and pore size of polyacrylonitrile-based super-microporous carbon nanospheres in a planned manner, the conductivity is improved but the conductive rate is slow. Through the "semi-anchored strategy", the grafting density of polymeric ionic liquid cations on the surface of super-microporous carbon nanospheres is precisely controlled, a composite system with both screening skeleton stability and ion transport channel continuity is developed, interface adjustment is accurately performed to reduce the seepage threshold and mediate ion transport, selective ion separation is achieved, functionalization and pore integrity are synergistically optimized, and ultra-high desalination performance and excellent selectivity of the flow electrode capacitive deionization system are obtained.

[0048] The ionic liquid such as 1-vinyl-3-ethyl imidazole bromide salt is grafted onto the surface of polyacrylonitrile-based super-microporous carbon nanospheres to prepare polymeric ionic liquid super-microporous carbon nanospheres with a structured interface network structure. The cations of 1-vinyl-3-ethyl imidazole bromide salt are polymerized on the surface of the carbon nanospheres, the anions have a dynamic migration ability within a certain limit, the wettability of the material is enhanced, the formation of non-contact areas is reduced, a more continuous and efficient charge seepage network is constructed, the path is shorter, and the energy barrier is lower. The free-moving anions (CH3COO -) The ion transmission rate is adjusted by coordination, and the gradient selective transmission of ions is realized by synergistic effect with the cation conductive network on the interface. A more continuous and efficient charge percolation network is constructed, which has a shorter path and lower energy barrier.

[0049] The prepared semi-anchored polymeric ionic liquid super-microporous carbon nanospheres can be used for industrial seawater desalination to produce fresh water, and the Mg 2+ transmission while ensuring the Na + mobility is enhanced, thereby significantly improving the desalination efficiency, and the desalination mechanism is as shown in Figure 2 The semi-anchored polymeric ionic liquid super-microporous carbon nanospheres material is selected as the electrode, and the precise percolation network and excellent ion selectivity are utilized to strengthen the removal of Na + . The prepared semi-anchored polymeric ionic liquid super-microporous carbon nanospheres material exhibits excellent deionization performance, and the performance ranks in the front among all the flow electrode capacitive deionization systems reported in the literature. Specifically, the anchored polymeric ionic liquid super-microporous carbon nanospheres can be used in the electrode slurry to prepare a flow electrode capacitive deionization device, and the flow electrode capacitive deionization electrode material has excellent ion selectivity for Na + , and is suitable for an industrial seawater desalination system for producing fresh water. Based on the efficient charge percolation network and excellent ion selectivity, the desalination efficiency of brine is improved.

[0050] Through experiments, it is verified that the prepared semi-anchored polymeric ionic liquid super-microporous carbon nanospheres, when used as a flow electrode in a Na + recovery system, exhibit an average salt adsorption rate of 22.89 μg cm -2 min -1 , and achieve excellent separation performance with a selectivity coefficient + of 2.18 in a Na 2+ / Mg -1 mixed solution, with a deionization performance improved by 28.27% and energy consumption reduced by 18.26%. The efficient charge percolation network and excellent ion selectivity improve the desalination efficiency of brine.

[0051] The schemes of the present application will be described below in combination with the drawings, wherein the experimental methods not specifically described in the operation steps are performed according to the corresponding product instructions. The instruments, reagents and consumables used in the examples can be purchased from commercial companies, unless otherwise specified.

[0052] Example 1: Preparation of semi-anchored polymeric ionic liquid super-microporous carbon nanospheres

[0053] ultrasonic emulsification for 60 min at 40℃. The emulsified solution was bubbled with nitrogen for 30 min, 0.3 g of water-soluble initiator potassium persulfate was added, and the reaction system was stirred at 74℃ for 3 h to obtain a white product, which was filtered and washed with water and dried. The white product was transferred to a tube furnace, pre-oxidized at 250℃ for 1 h at a heating rate of 0.5℃ min -1 under air atmosphere, and then carbonized at 850℃ for 1 h under nitrogen atmosphere at a heating rate of 2℃ min -1 to obtain the ultramicroporous carbon nanospheres.

[0054] The ultramicroporous carbon nanospheres were ultrasonically dispersed with ionic liquid 1-vinyl-3-ethylimidazolium bromide at a molar ratio of 3:1 in 100 mL solvent chloroform for 30 min. The chloroform solution was then transferred to a Schlenk tube, bubbled with nitrogen for 30 min, and 0.03 g of oil-soluble initiator azobisisobutyronitrile was added. The reaction was stirred at 70℃ for 3 h, and the product was filtered, washed, and dried to obtain a solid product.

[0055] The solid product was dispersed in anhydrous ethanol, and a mixed solution of anhydrous sodium acetate and anhydrous ethanol with a mass fraction of 20% was slowly added dropwise. The reaction was then carried out at 60℃ for 24 h to obtain the final semi-anchored polymer ionic liquid ultramicroporous carbon nanospheres.

[0056] The prepared ultramicroporous carbon nanospheres were characterized. As shown in the SEM of Figure 3 a, the semi-anchored polymer ionic liquid ultramicroporous carbon nanospheres after grafting maintained a good spherical structure and uniform size distribution, about 102±5 nm, which was 21±5 nm larger than the original particle size of 81±5 nm of the polyacrylonitrile-based ultramicroporous carbon nanospheres before grafting, forming a 1-vinyl-3-ethylimidazolium bromide layer on the surface of the polyacrylonitrile-based ultramicroporous carbon nanospheres. As shown in the TEM images of Figure 3 b and Figure 3 c, the surface of the semi-anchored polymer ionic liquid ultramicroporous carbon nanospheres became rough after the semi-anchoring treatment of 1-vinyl-3-ethylimidazolium bromide. The crosslinked network structure can be seen in the 50 nm scale figure, showing a complete percolation network, which is beneficial to improve the charge transfer rate.

[0057] As shown in Figure 4 a, it can be seen from the adsorption-desorption isotherm that the absorption and desorption curves of CO2 of the semi-anchored polymer ionic liquid ultramicroporous carbon nanospheres are still type I isotherm, indicating that the semi-anchored polymer ionic liquid ultramicroporous carbon nanospheres are still microporous structures. As shown in Figure 4As shown in FIG. 8B, the pore size distribution diagram shows that the grafting of 1-vinyl-3-ethylimidazole bromide salt does not block the existing ultramicropores, but instead, through electrostatic attraction, π-π stacking and other interactions of 1-vinyl-3-ethylimidazole bromide salt, the molecules are driven to arrange in a regular microporous channel (0.85±0.02 nm).

[0058] The contact angle test was performed on the polyacrylonitrile-based ultramicroporous carbon nanospheres before grafting of the ionic liquid, as shown in FIG. 8A. Figure 5 As shown in FIG. 8B, the pore size distribution diagram shows that the grafting of 1-vinyl-3-ethylimidazole bromide salt does not block the existing ultramicropores, but instead, through electrostatic attraction, π-π stacking and other interactions of 1-vinyl-3-ethylimidazole bromide salt, the molecules are driven to arrange in a regular microporous channel (0.85±0.02 nm).

[0059] The above results show that the ultramicroporous carbon nanospheres of the semi-anchored polymerized ionic liquid have been successfully prepared by the semi-anchored strategy, the ultramicroporous framework is retained, additional micropores are introduced, the charge percolation network is promoted, and thus the charge transport is improved.

[0060] Example 2: Preparation of electrode material

[0061] The semi-anchored polymerized ionic liquid ultramicroporous carbon nanospheres prepared in Example 1 were prepared into an electrode. The specific steps include the following.

[0062] The semi-anchored polymerized ionic liquid ultramicroporous carbon nanospheres, acetylene black and polyvinylidene fluoride were added into N-methylpyrrolidone in a mass ratio of 8:1:1, ultrasonically dispersed and uniformly mixed to form a uniform electrode slurry. The slurry was carefully and uniformly applied on a graphite paper (5 cm x 6 cm) and dried at 80°C for 12 h to form an electrode.

[0063] The capacitance performance of the electrode material was tested to be 147.16 F g-1 with 1M NaCl as the electrolyte solution. -1 As shown in FIG. 8C, which is an electrochemical cycle diagram of the electrode material, the results prove that the semi-anchored polymerized ionic liquid remains stable in long-term electrochemical desalination, and the structure has stability. Figure 6

[0064] Example 3:

[0065] The semi-anchored polymerized ionic liquid ultramicroporous carbon nanospheres prepared in Example 1 were prepared into a flow electrode. The specific steps include the following.

[0066] ​The FCDI device is composed of two pieces of graphite current collector (95 mm x 80 mm x 7 mm), two pieces of ion exchange membrane and a piece of hollow organic glass plate (thickness 3-7 mm). The serpentine flow channels (2 mm wide x 2 mm deep) are etched on the inner side of the current collector, with 11 channels and an effective contact area of 9.2 cm 2 The above components are clamped and fixed by two end plates, sealed by silica gel gasket, and assembled to form a complete FCDI reaction unit.

[0067] The ultra-microporous carbon nanospheres containing semi-anchored polymeric ionic liquid are dispersed in a 500 mg / L sodium chloride solution to prepare a flow electrode. The flow electrode is introduced into the FCDI reaction unit by a peristaltic pump, a voltage (1.2 V) is applied, and the reaction current is recorded synchronously to calculate the desalination efficiency, salt adsorption capacity (SAC), energy consumption (Em) and other indicators.

[0068] The results show that the electrode slurry containing 3.33wt% of semi-anchored polymeric ionic liquid ultra-microporous carbon nanospheres can maintain high desalination capacity and Na + selectivity. Compared with the unmodified polyacrylonitrile-based ultra-microporous carbon nanospheres UCNs, the semi-anchored polymeric ionic liquid modified polyacrylonitrile-based ultra-microporous carbon nanospheres UCNs@PILs material improves the removal efficiency, energy consumption reduction and Na + selectivity by 28.00%, 18.26% and 39.40% respectively, showing excellent desalination performance and anti-multiple ion interference ability.

[0069] The above embodiments of the present application are described in detail, but the content is only the preferred embodiment of the present application, and cannot be considered to limit the scope of the present application. Any equivalent changes and improvements made in the scope of the present application should still be within the scope of the present application.

Claims

1. A method for preparing a semi-anchored polymeric ionic liquid super-microporous carbon nanospheres, characterized in that: The water-soluble initiator is added to the emulsified reaction monomer acrylonitrile, and the product obtained by polymerization is sequentially oxidized and carbonized to obtain the ultra-microporous carbon nanospheres; under the action of the oil-soluble initiator, the ionic liquid is grafted to the surface of the polyacrylonitrile-based ultra-microporous carbon nanospheres to obtain the semi-anchored polymeric ionic liquid ultra-microporous carbon nanospheres.

2. The process for the preparation of semi-anchored polymeric ionic liquid- infused ultramicroporous carbon nanospheres according to claim 1, characterized in that: The ionic liquid is one of 1-vinyl-3-ethyl imidazole bromide, 1-vinyl-3-cyanethyl imidazole bromide, 1-vinyl-3-sulfopropyl imidazole bromide and 1-vinyl-3-aminopropyl imidazole bromide. Preferably, the water-soluble initiator is potassium persulfate. The oil-soluble initiator is azobisdimethyl isobutyronitrile.

3. The method for preparing ultraporous carbon nanospheres of semi-anchored polymeric ionic liquid according to claim 1 or 2, characterized in that: The specific steps are as follows: Step one: the emulsifier and the reaction monomer acrylonitrile are dissolved in water, and ultrasonic emulsification is performed at 30-50°C; Step two: the water-soluble initiator is added to the emulsified solution, and the obtained polymerization product is stirred at 60-80°C; Step three: the polymerization product is pre-oxidized at 250°C in an air atmosphere for 1-3h; and then carbonized at 750-1050°C in a nitrogen atmosphere for 1-3h to obtain the polyacrylonitrile-based ultra-microporous carbon nanospheres; Step four: the polyacrylonitrile-based ultra-microporous carbon nanospheres and the ionic liquid are added to a solvent; Step five: the mixed solution is placed in a nitrogen environment, the oil-soluble initiator added accounts for 0.02-0.2% of the mass of the monomer, and the product is obtained by stirring at 60-80°C; Step six: the solid product is dispersed in anhydrous ethanol, a mixed solution of 20% anhydrous acetic acid sodium and anhydrous ethanol is slowly added dropwise, and the semi-anchored polymeric ionic liquid ultra-microporous carbon nanospheres are obtained by reaction at 60-80°C.

4. The method for preparing ultraporous carbon nanospheres of semi-anchored polymeric ionic liquid according to claim 3, characterized in that: The mass ratio of the emulsifier, the reaction monomer and the water-soluble initiator is 1:40:0.

12.

5. The method for preparing ultraporous carbon nanospheres of semi-anchored polymeric ionic liquid according to claim 3, characterized in that: The molar ratio of the polyacrylonitrile-based ultra-microporous carbon nanospheres and the ionic liquid is 3:

1.

6. The semi-anchored polymeric ionic liquid ultra-microporous carbon nanospheres prepared by the method of any one of claims 1-5.

7. An electrode characterized by: The semi-anchored polymeric ionic liquid ultra-microporous carbon nanospheres of claim 6.

8. The electrode of claim 7, wherein: The semi-anchored polymeric ionic liquid ultra-microporous carbon nanospheres, acetylene black and polyvinylidene fluoride are added to N-methyl pyrrolidone in a mass ratio of 8:1:1 to form a uniform electrode slurry, which is applied to the pole piece and dried to obtain an electrode.

9. A flow electrode capacitive deionization device comprising the electrode of claim 7 or 8.

10. A system for producing fresh water from seawater desalination, characterized in that: The electrode of claim 7 or 8. The electrode of claim 7 or 8.

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