Betaine adsorption modified activated carbon for water system super capacitor and preparation method of betaine adsorption modified activated carbon

Abstract

The invention discloses betaine adsorption modified activated carbon for a water system supercapacitor and a preparation method of the betaine adsorption modified activated carbon, which are used for optimizing a water system electrolyte / electrode interface and have an obvious widening effect on a working voltage window of the water system supercapacitor. The method mainly comprises the following steps: 1, dissolving and mixing anhydrous betaine and deionized water according to a set proportion to prepare an impregnation liquid; 2, adding activated carbon YP-50F into the impregnation liquid in proportion, performing ultrasonic dispersion for 30 minutes, and stirring and mixing for 16 hours; and 3, carrying out vacuum filtration on the solution, retaining the precipitate, and then carrying out vacuum drying for 12 hours to obtain a powdery betaine modified activated carbon sample. The method has the advantages of simple steps, mild reaction, cheap and easily available raw materials and convenience in large-scale production, the prepared modified activated carbon retains the porous structure of an initial sample, the surface active groups are increased, the working voltage of an assembled device based on the modified activated carbon is obviously improved, and a new solution is provided for an aqueous electrolyte / electrode interface optimization scheme.

Description

Technical Field

[0001] The present invention belongs to the technical field of modification of supercapacitor electrode materials, and particularly relates to a betaine-adsorbed modified activated carbon for aqueous supercapacitors and a preparation method thereof. Background Art

[0002] Among various energy storage systems, electrochemical energy storage has become one of the most promising energy storage methods due to its high energy conversion efficiency, mobility, and noiseless pollution. Batteries, electrochemical supercapacitors, and fuel cells are recognized as the three most important electrochemical energy storage technologies. Among them, supercapacitors, as an electrical energy source with fast charge and discharge, long cycle life, high power, and low cost, have been widely studied.

[0003] Among many electrode materials for supercapacitors, porous carbon materials have been studied the most and have the greatest potential for industrial applications. Currently, the electrode material of commercial supercapacitors is mainly activated carbon, which has the advantages of low cost, easy availability, and high power density, and its structure is relatively stable. However, its specific capacitance is low and the internal resistance is relatively large, which limits its use in the field of high-power supercapacitors. According to the different main principles and characteristics of the treatment technologies, the surface modification and decoration technologies of activated carbon can be roughly divided into two categories: physical modification technologies and chemical modification technologies.

[0004] An electrolyte generally consists of an electrolyte salt and a solvent and belongs to an ionic conductor. Its physical and chemical properties have a crucial impact on the performance of the devices assembled with it (such as working voltage window, cycle life, safety, rate performance, cost, etc.). At the same time, the interaction between the electrolyte and the electrode will affect the working voltage and cycle life of the supercapacitor.

[0005] Compared with commercial organic electrolytes, aqueous electrolytes have outstanding advantages in terms of safety, environmental friendliness, and ionic conductivity. However, due to the low thermodynamic decomposition voltage of water (only 1.23V), the working voltage of aqueous supercapacitors is generally low (usually not higher than 1V). Currently, the mainstream research still focuses on the modification design of the aqueous electrolyte itself to broaden the working voltage window of aqueous electrochemical devices, and rarely conducts research starting from the electrolyte / electrode interface. Summary of the Invention

[0006] The purpose of the present invention is to provide a betaine-adsorbed modified activated carbon for aqueous supercapacitors and a preparation method thereof. The method is simple and feasible. Based on this preparation method, the obtained modified activated carbon retains the porous and amorphous structure of the initial sample, the surface active groups are significantly increased, the decomposition reaction of free water at the interface is slowed down and inhibited, and the working voltage of the device prepared based on the modified activated carbon is increased.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions: A preparation method of betaine-adsorbed modified activated carbon for aqueous supercapacitors, comprising the following steps: 1) Add anhydrous betaine to deionized water and fully dissolve it at room temperature to prepare an impregnating solution; 2) Add activated carbon YP-50F to the impregnating solution and disperse it by ultrasonic treatment to form a black suspension; 3) Stir the black suspension at high speed at room temperature until it is uniformly dispersed; 4) Vacuum filter the stirred solution until the liquid is clear, and retain the precipitate; 5) Vacuum dry the obtained precipitate, and the obtained black powder sample is betaine-adsorbed modified activated carbon.

[0008] A further improvement of the present invention is that in step 1), the mass ratio of anhydrous betaine to deionized water is (0.1-1):25.

[0009] A further improvement of the present invention is that in step 2), the mass ratio of anhydrous betaine to activated carbon is (0.1-1):2.

[0010] A further improvement of the present invention is that in step 2), the ultrasonic treatment is carried out for 30 min using a cell crusher under ice bath conditions to obtain a black suspension.

[0011] A further improvement of the present invention is that in step 2), the activated carbon particles are dispersed in the impregnating solution, and the physical adsorption of betaine molecules is realized by using the porous structure of the activated carbon.

[0012] A further improvement of the present invention is that in step 3), the black suspension is stirred at high speed at room temperature on a stirring table, and the rotation speed is 800-1000 revolutions per minute.

[0013] A further improvement of the present invention is that in step 4), the stirred solution is vacuum filtered 3 times.

[0014] A further improvement of the present invention is that in step 5), the obtained precipitate is placed in a vacuum drying oven and dried for 12 h and then taken out.

[0015] A further improvement of the present invention is that in step 5), the vacuum drying temperature is 70°C-80°C.

[0016] A kind of betaine-adsorbed modified activated carbon for aqueous supercapacitors prepared by the said preparation method.

[0017] Compared with the prior art, the present invention has at least the following beneficial technical effects: (1)The present invention provides a method for preparing betaine-adsorbed and modified activated carbon for aqueous supercapacitors. This method is simple and easy to implement, with rich sources of raw materials, a simple product formula, mild reaction conditions, controllable preparation methods, and stable products. Compared with conventionally used activated carbon, the content of surface active groups has been significantly increased, and the porous structure has been retained with fewer defects introduced. (2)The surface active groups of the betaine-adsorbed and modified activated carbon prepared by the present invention are increased. Adsorbed at the contact interface between the electrode and the electrolyte, it can slow down the decomposition reaction of water molecules at the electrolyte / electrode interface.

[0018] (3)The betaine-adsorbed and modified activated carbon obtained by the preparation method of the present invention can be used as the electrode of an aqueous supercapacitor. The working voltage of the device based on the modified electrode has been significantly increased. Among them, the working voltage of the AC@B-2 device has been extended to 1.4 V. The results of constant current charge and discharge tests show that it has the largest specific capacitance and good rate performance at the same time.

[0019] (4)Starting from the electrolyte / electrode interface, the present invention uses the zwitterionic surfactant betaine to adsorb on the surface of the activated carbon electrode to construct a waterproof layer, so as to slow down the decomposition reaction of water at the interface and broaden the working voltage of the device, providing a new solution for the modification of aqueous supercapacitors. Description of the Drawings

[0020] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Figure 1 Among them, a~b are SEM images of the modified activated carbon prepared in Example 1 of the present invention.

[0022] Figure 2 is the FT-IR image of the modified activated carbon prepared in Example 1 of the present invention.

[0023] Figure 3 is a schematic diagram of the contact angle between the betaine-adsorbed and modified activated carbon electrode sheets prepared in Example 1, Example 2, and Example 3 and 1 M LiCl electrolyte.

[0024] Figure 4 is the CV curve of the coin-type supercapacitor prepared in Example 1 of the present invention within different working voltage ranges at 100 mV / s.

[0025] Figure 5The rate performance curve of the button-type supercapacitor prepared in Example 1 of the present invention at different current densities. Detailed implementation manners

[0026] In the following text, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the drawings and the description are considered to be exemplary in nature rather than restrictive.

[0027] It should be understood that when used in this specification and the appended claims, the terms "comprises" and "comprising" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0028] It should also be understood that the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0029] It should be further understood that the term " / and" used in the specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0030] Schematic diagrams of various structures according to the disclosed embodiments of the present invention are shown in the drawings. These figures are not drawn to scale, where for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures and their relative sizes and positional relationships are only exemplary, and may actually deviate due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0031] The embodiments of the present invention will be described in detail below with reference to the drawings.

[0032] In a first aspect, the present invention provides a method for preparing betaine-adsorbed modified activated carbon for an aqueous supercapacitor, comprising the following steps: 1) Weigh a certain mass of anhydrous betaine, add 25 mL of deionized water, and fully dissolve it at room temperature to prepare an impregnation solution; 2) Weigh a certain mass of activated carbon YP-50F, add the above impregnation solution, and ultrasonically disperse it for 30 min to form a black suspension; 3) Stir the black mixed suspension at high speed at room temperature until it is evenly dispersed, with a stirring rate of 800 - 1000 revolutions per minute; 4) Vacuum filter the solution 3 times until the liquid is clear, and retain the precipitate; 5) Place the obtained precipitate in a vacuum drying oven and dry it at 70 °C - 80 °C for 12 h, then take it out. The obtained black powder sample is the betaine-adsorbed modified activated carbon.

[0033] In the second aspect, the present invention inhibits the decomposition reaction of free water molecules at the interface by physically adsorbing betaine molecules on the surface of the activated carbon electrode, thereby broadening the working voltage of the device. At the same time, the adsorbed betaine molecules can improve the adsorption capacity for lithium ions in the electrolyte, optimize the electric double layer distribution, and thus cause an increase in the energy storage capacity.

[0034] In the third aspect, the present invention provides an application of the betaine-modified activated carbon. The modified activated carbon can be used as an electrode material for aqueous supercapacitors, and specifically includes the following steps: First, grind the modified activated carbon, polyvinylidene fluoride (PVDF), and conductive carbon black evenly at a mass ratio of 8:1:1, then add an appropriate amount of N-methyl-2-pyrrolidone (NMP) solvent and grind again to make the slurry evenly mixed. Then, coat the well-mixed slurry on a nickel foil pretreated with ethanol and acetone. Finally, vacuum dry the electrode at 80 °C for 12 h and punch it into a 12 mm round piece for standby.

[0035] Assemble a glass fiber separator with a diameter of 16 mm, 1 M lithium chloride electrolyte, and an electrode with a diameter of 12 mm in the order of negative electrode shell, electrode sheet, electrolyte, separator, electrolyte, electrode sheet, gasket, elastic sheet, and positive electrode shell, and use a button cell sealer for encapsulation to obtain a button-type supercapacitor for subsequent electrochemical performance testing.

[0036] Example 1 Weigh anhydrous betaine, activated carbon YP-50F, and deionized water according to a mass ratio of 0.1:2:25. Add anhydrous betaine to deionized water and fully dissolve it to prepare an impregnation solution; add activated carbon YP-50F to the impregnation solution and ultrasonically disperse it for 30 minutes to obtain a black suspension; then stir it at high speed at room temperature for 16 h until fully mixed; then vacuum filter the black suspension 3 times using a 0.22 μm cellulose filter membrane, and vacuum dry the obtained precipitate at 80 °C for 12 h to obtain the betaine-modified activated carbon powder.

[0037] The prepared betaine-modified activated carbon was used as the electrode material of an aqueous supercapacitor for assembly and testing. The specific steps are as follows: First, the modified activated carbon, polyvinylidene fluoride (PVDF), and conductive carbon black were ground evenly in a mass ratio of 8:1:1. Then, an appropriate amount of N-methyl-2-pyrrolidone (NMP) solvent was added and ground again to make the slurry well mixed. Then, the well-mixed slurry was coated on a nickel foil pretreated with ethanol and acetone. Finally, the electrode was vacuum dried at 70 °C to 80 °C for 12 h and punched into 12 mm round pieces for standby.

[0038] A glass fiber separator with a diameter of 16 mm, 1 M lithium chloride electrolyte, and an electrode with a diameter of 12 mm were assembled in the order of negative electrode shell, electrode sheet, electrolyte, separator, electrolyte, electrode sheet, gasket, elastic sheet, and positive electrode shell. A button-type supercapacitor was obtained by encapsulation using a button cell sealer for subsequent electrochemical performance testing.

[0039] Example 2 Anhydrous betaine, activated carbon YP-50F, and deionized water were weighed in a mass ratio of 0.4:2:25. The anhydrous betaine was added to deionized water and fully dissolved to prepare an impregnating solution. The activated carbon YP-50F was added to the impregnating solution and ultrasonically dispersed for 30 minutes to obtain a black suspension. Subsequently, it was vigorously stirred at room temperature for 16 h until well mixed. Subsequently, the black suspension was vacuum filtered 3 times using a 0.22 μm cellulose filter membrane, and the obtained precipitate was vacuum dried at 80 °C for 12 h to obtain betaine-modified activated carbon powder.

[0040] The prepared betaine-modified activated carbon was used as the electrode material of an aqueous supercapacitor for assembly and testing. The specific steps are as follows: First, the modified activated carbon, polyvinylidene fluoride (PVDF), and conductive carbon black were ground evenly in a mass ratio of 8:1:1. Then, an appropriate amount of N-methyl-2-pyrrolidone (NMP) solvent was added and ground again to make the slurry well mixed. Then, the well-mixed slurry was coated on a nickel foil pretreated with ethanol and acetone. Finally, the electrode was vacuum dried at 70 °C to 80 °C for 12 h and punched into 12 mm round pieces for standby.

[0041] A glass fiber separator with a diameter of 16 mm, 1 M lithium chloride electrolyte, and an electrode with a diameter of 12 mm were assembled in the order of negative electrode shell, electrode sheet, electrolyte, separator, electrolyte, electrode sheet, gasket, elastic sheet, and positive electrode shell. A button-type supercapacitor was obtained by encapsulation using a button cell sealer for subsequent electrochemical performance testing.

[0042] Example 3 Weigh anhydrous betaine, activated carbon YP-50F and deionized water according to the mass ratio of 1:2:25. Add anhydrous betaine to deionized water and fully dissolve it to prepare an impregnation solution. Add activated carbon YP-50F to the impregnation solution and ultrasonically disperse it for 30 minutes to obtain a black suspension. Then, stir it at high speed at room temperature for 16 h until fully mixed. Subsequently, vacuum filter the black suspension 3 times using a 0.22 μm cellulose filter membrane, and vacuum dry the obtained precipitate at 80 °C for 12 h to obtain betaine-modified activated carbon powder.

[0043] Use the prepared betaine-modified activated carbon as the electrode material of an aqueous supercapacitor for assembly and testing. The specific steps are as follows: First, grind the modified activated carbon, polyvinylidene fluoride (PVDF) and conductive carbon black evenly according to the mass ratio of 8:1:1, then add an appropriate amount of N-methyl-2-pyrrolidone (NMP) solvent and grind again to make the slurry evenly mixed. Then, coat the fully mixed slurry on a nickel foil pretreated with ethanol and acetone. Finally, vacuum dry the electrode at 70 °C - 80 °C for 12 h and punch it into a 12 mm round piece for standby.

[0044] Assemble a glass fiber separator with a diameter of 16 mm, 1 M lithium chloride electrolyte and an electrode with a diameter of 12 mm in the order of negative electrode shell, electrode sheet, electrolyte, separator, electrolyte, electrode sheet, gasket, spring piece, positive electrode shell, and use a button cell sealing machine for encapsulation to obtain a button-type supercapacitor for subsequent electrochemical performance testing.

[0045] Example 4 Weigh anhydrous betaine, activated carbon YP-50F and deionized water according to the mass ratio of 0.1:2:25. Add anhydrous betaine to deionized water and fully dissolve it to prepare an impregnation solution. Add activated carbon YP-50F to the impregnation solution and ultrasonically disperse it for 30 minutes to obtain a black suspension. Then, stir it at high speed at room temperature for 16 h until fully mixed. Subsequently, vacuum filter the black suspension 3 times using a 0.22 μm cellulose filter membrane, and vacuum dry the obtained precipitate at 80 °C for 12 h to obtain betaine-modified activated carbon powder.

[0046] Use the prepared betaine-modified activated carbon as the electrode material of an aqueous supercapacitor for assembly and testing. The specific steps are as follows: First, grind the modified activated carbon, polyvinylidene fluoride (PVDF) and conductive carbon black evenly according to the mass ratio of 8:1:1, then add an appropriate amount of N-methyl-2-pyrrolidone (NMP) solvent and grind again to make the slurry evenly mixed. Then, coat the fully mixed slurry on a nickel foil pretreated with ethanol and acetone. Finally, vacuum dry the electrode at 70 °C - 80 °C for 12 h and punch it into a 12 mm round piece for standby.

[0047] A glass fiber diaphragm with a diameter of 16 mm, 1 M dilute sulfuric acid electrolyte, and an electrode with a diameter of 12 mm were assembled in the order of negative electrode shell, electrode sheet, electrolyte, diaphragm, electrolyte, electrode sheet, gasket, elastic sheet, and positive electrode shell, and were encapsulated using a button cell sealing machine to obtain a button-type supercapacitor for subsequent electrochemical performance testing.

[0048] Example 5 Weigh anhydrous betaine, activated carbon YP-50F, and deionized water according to a mass ratio of 0.1:2:25. Add anhydrous betaine to deionized water and fully dissolve it to prepare an impregnating solution; add activated carbon YP-50F to the impregnating solution and ultrasonically disperse it for 30 minutes to obtain a black suspension; then stir it at high speed at room temperature for 16 h until fully mixed; then vacuum filter the black suspension 3 times using a 0.22 μm cellulose filter membrane, and vacuum dry the obtained precipitate at 80 °C for 12 h to obtain betaine-modified activated carbon powder.

[0049] The prepared betaine-modified activated carbon was used as the electrode material of an aqueous supercapacitor for assembly testing. The specific steps are as follows: First, grind the modified activated carbon, polyvinylidene fluoride (PVDF), and conductive carbon black evenly according to a mass ratio of 8:1:1, then add an appropriate amount of N-methyl-2-pyrrolidone (NMP) solvent and grind again to make the slurry evenly mixed, and then coat the fully mixed slurry on a nickel foil pretreated with ethanol and acetone. Finally, vacuum dry the electrode at 70 °C to 80 °C for 12 h and punch it into a 12 mm round piece for standby.

[0050] A glass fiber diaphragm with a diameter of 16 mm, 6 M potassium hydroxide electrolyte, and an electrode with a diameter of 12 mm were assembled in the order of negative electrode shell, electrode sheet, electrolyte, diaphragm, electrolyte, electrode sheet, gasket, elastic sheet, and positive electrode shell, and were encapsulated using a button cell sealing machine to obtain a button-type supercapacitor for subsequent electrochemical performance testing; the scanning rate for the working voltage test was 100 mV / s, the current density for the constant current charge-discharge test was 1 A / g, and the current density range for the rate performance test was 1 A / g to 10 A / g.

[0051] Figure 1 This is the SEM morphology diagram of activated carbon before and after betaine adsorption modification at the same magnification; the SEM test results show that the adsorbed and modified activated carbon still retains the porous structure of the substrate material, and the modification method is mild. Figure 2 This is the FT-IR diagram of activated carbon before and after betaine adsorption modification. The surface active group -C=O of the modified activated carbon increases significantly, proving that the hydrophilic group -C=O after the hydrolysis of betaine molecules is successfully adsorbed on the surface of the porous carbon.

[0052] Figure 3Contact angles of the betaine-adsorbed and modified activated carbon electrode sheets prepared for Example 1, Example 2, and Example 3 with 1 M LiCl electrolyte. The test results show that the contact angle increases after modification, and the adsorbed betaine helps to isolate the side reaction of water molecule decomposition at the interface.

[0053] Figure 4 CV curves of AC and AC@B-2 devices at the same scanning rate are shown. The test results indicate that the working voltage window of the unmodified activated carbon AC device is only 1.0 V; while the AC@B-2 device can still maintain a CV curve shape similar to a rectangle at 1.4 V, indicating its fast current-voltage response ability, and proving that betaine adsorption modification can effectively inhibit the side reaction of the electrolyte at the interface and broaden the voltage window.

[0054] Figure 5 The rate performance curves of AC and AC@B-2 devices at different current densities are shown. The test results indicate that their specific capacitances at a current density of 1 A / g are 19.12 F / g and 26.6 F / g respectively, proving that betaine adsorption can promote ion transport and increase the energy storage capacity while broadening the voltage window. In addition, the capacity retention rates of AC and AC@B-2 devices at a current density of 10 A / g are 86.9% and 87.3% respectively, indicating that both have good rate performance.

[0055] The above shows and describes the basic principles, main features, and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0056] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing betaine adsorption modified activated carbon for aqueous supercapacitors, characterized in that: The following steps are involved: 1) Add deionized water to anhydrous betaine and fully dissolve it at room temperature to prepare an impregnation solution; 2) Add activated carbon YP-50F to the impregnation solution and disperse it by ultrasonic to form a black suspension; 3) Stir the black suspension at high speed at room temperature until it is evenly dispersed; 4) Vacuum filter the stirred solution until the liquid is clear and retain the precipitate; 5) The obtained precipitate is vacuum dried, and the obtained black powder sample is the betaine adsorption modified activated carbon.

2. The method for preparing a betaine adsorbed modified activated carbon for an aqueous supercapacitor according to claim 1, characterized in that: In step 1), the mass ratio of anhydrous betaine to deionized water is (0.1-1):

25.

3. A method for preparing betaine-adsorbed modified activated carbon for aqueous supercapacitors according to the claims, characterized in that: In step 2), the mass ratio of anhydrous betaine to activated carbon is (0.1-1):

2.

4. The method for preparing a betaine adsorbed modified activated carbon for an aqueous supercapacitor according to claim 1, characterized in that: In step 2), a black suspension was obtained by ultrasonic treatment of the cell disruptor for 30 min in an ice bath.

5. The method for preparing a betaine adsorbed modified activated carbon for aqueous supercapacitors according to claim 1, characterized in that: In step 2), activated carbon particles are dispersed in the impregnation solution, and the porous structure of the activated carbon is used to achieve physical adsorption of betaine molecules.

6. The method for preparing a betaine adsorbed modified activated carbon for aqueous supercapacitors according to claim 1, characterized in that: In step 3), the black suspension is stirred at high speed at room temperature on a stirring table at a speed of 800 to 1000 rpm.

7. The method for preparing a betaine adsorbed modified activated carbon for an aqueous supercapacitor according to claim 1, characterized in that: In step 4), the stirred solution was vacuum filtered three times.

8. The method for preparing a betaine adsorbed modified activated carbon for aqueous supercapacitors according to claim 1, characterized in that: In step 5), the obtained precipitate is placed in a vacuum drying oven and dried for 12 hours and then taken out.

9. The method for preparing a betaine adsorbed modified activated carbon for aqueous supercapacitors according to claim 1, characterized in that: In step 5), the vacuum drying temperature is 70°C to 80°C.

10. A betaine adsorbed modified activated carbon for aqueous supercapacitors prepared by the preparation method according to any one of claims 1 to 9.

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