Electrode material, preparation method therefor and use thereof

Abstract

The application provides an electrode material and a preparation method and application thereof, and belongs to the technical field of electrode materials. The carbon nanotubes are pretreated in mixed acid to improve the dispersibility of the carbon nanotubes and make the openings of the carbon nanotubes form hollow structures, then the carbon nanotubes are subjected to in-situ polymerization reaction with graphene and nitrogen-containing polymer monomers, the two-dimensional flaky graphene and the tubular carbon nanotubes are mutually overlapped to form a porous structure, which is beneficial to the transmission of electrolyte, in the polymerization process, the polymer is wrapped on the surfaces of the graphene and the carbon nanotubes to form a core-shell structure, the volume change of the electrode material in the charging and discharging process can be avoided, meanwhile, the doping of nitrogen can improve the surface polarity of the electrode material, provide lone pair electrons, enhance the conductivity, and introduce pseudo-capacitance to improve the specific capacitance of the electrode material; the alkaline activator is used for activation to increase the specific surface area of the material, and further improve the electrochemical performance of the electrode material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrode materials, and particularly relates to an electrode material and a preparation method and application thereof. BACKGROUND

[0002] The super capacitor is also called an electrochemical capacitor, and has the advantages of high power density, fast charging and discharging speed, long service life, good safety performance and small pollution, and has become a new type of energy storage device which is concerned by the whole world. The super capacitor can be widely applied to fields such as standby power supply, portable power supply and hybrid electric vehicle power supply, and has a good application prospect.

[0003] The super capacitor is composed of positive and negative electrode sheets (electrode materials), electrolyte, diaphragm, current collector and packaging material. The performance of the super capacitor mainly depends on the electrode materials on the positive and negative electrode sheets. At present, the material used for the super capacitor is mainly amorphous carbon material, because the interlayer spacing of the amorphous carbon material is large, which is beneficial to improving the large current charging and discharging performance of the electrode, but the conductivity of the amorphous carbon material is poor, so that the specific capacitance of the assembled super capacitor is relatively low, only about 100 Fg -1 , thereby limiting the application thereof. SUMMARY

[0004] The purpose of the application is to provide an electrode material and a preparation method and application thereof. The electrode material prepared by the preparation method provided by the application has a higher specific capacitance of the super capacitor assembled by the electrode material.

[0005] In order to achieve the above-mentioned purpose, the application provides the following technical scheme:

[0006] The application provides a preparation method of an electrode material, comprising the following steps:

[0007] (1) mixing carbon nanotubes with concentrated sulfuric acid and concentrated nitric acid for pretreatment to obtain pretreated carbon nanotubes;

[0008] (2) mixing graphene oxide with water and a reducing agent for a reduction reaction to obtain graphene;

[0009] (3) mixing the pretreated carbon nanotubes obtained in the step (1) with the graphene obtained in the step (2), a solvent, a nitrogen-containing polymer monomer and an initiator for a polymerization reaction to obtain a precursor;

[0010] (4) performing heat treatment on the precursor obtained in the step (3) to obtain an intermediate;

[0011] (5) mixing the intermediate obtained in the step (4) with an alkaline activator for activation treatment to obtain an electrode material;

[0012] The step (1) and the step (2) have no time sequence.

[0013] Preferably, the mass ratio of the carbon nanotubes, the graphene and the nitrogen-containing polymer monomer in the step (3) is (1-5):(1-5):(9-50).

[0014] Preferably, the nitrogen-containing polymer monomer in the step (3) comprises pyrrole or aniline.

[0015] Preferably, the mass ratio of the nitrogen-containing polymer monomer and the initiator in the step (3) is 1:(0.5-2).

[0016] Preferably, the temperature of the heat treatment in the step (4) is 500-1000℃, and the time of the heat treatment is 1-5h.

[0017] Preferably, the alkaline activator in the step (5) comprises one or more of potassium hydroxide, sodium hydroxide, potassium carbonate and sodium carbonate.

[0018] Preferably, the mass ratio of the intermediate and the alkaline activator in the step (5) is 1:(1-5).

[0019] Preferably, the temperature of the activation treatment in the step (5) is 500-800℃, and the time of the activation treatment is 0.1-2h.

[0020] The application provides an electrode material prepared by the preparation method, which comprises graphene and carbon nanotubes, and pyrolytic nitrogen-doped carbon loaded on the graphene and the carbon nanotubes, wherein the pyrolytic nitrogen-doped carbon is obtained by pyrolysis and activation of a nitrogen-containing polymer.

[0021] The application further provides application of the electrode material in a supercapacitor.

[0022] The application provides a preparation method of an electrode material, comprising the following steps: (1) mixing carbon nanotubes with concentrated sulfuric acid and concentrated nitric acid for pretreatment to obtain pretreated carbon nanotubes; (2) mixing graphene oxide with water and a reducing agent for a reduction reaction to obtain graphene; (3) mixing the pretreated carbon nanotubes obtained in the step (1) with the graphene obtained in the step (2), a solvent, a nitrogen-containing polymer monomer and an initiator for a polymerization reaction to obtain a precursor; (4) performing heat treatment on the precursor obtained in the step (3) to obtain an intermediate; and (5) mixing the intermediate obtained in the step (4) with an alkaline activator for activation treatment to obtain the electrode material; and the step (1) and the step (2) have no time sequence. The carbon nanotubes are pretreated in mixed acid first, the dispersibility of the carbon nanotubes is improved, and the carbon nanotubes are opened to form a hollow structure, then the carbon nanotubes are subjected to in-situ polymerization reaction with graphene and a nitrogen-containing polymer monomer, the two-dimensional flaky graphene and the tubular carbon nanotubes are overlapped to form a porous structure, which is beneficial to the transmission of electrolyte, in the polymerization process, the polymer is wrapped on the surfaces of the graphene and the carbon nanotubes to form a core-shell structure, which can avoid the volume change of the electrode material in the charging and discharging process, meanwhile, the nitrogen-containing polymer monomer is adopted, the nitrogen doping can improve the surface polarity of the electrode material, improve the wettability of the material to electrolyte, is beneficial to the diffusion of electrolyte, and the nitrogen atom can provide lone pair electrons to enhance the conductivity, meanwhile, the pseudo capacitance is introduced to improve the specific capacitance of the electrode material; the alkaline activator is adopted for activation to increase the specific surface area of the material, and further improve the electrochemical performance of the electrode material. The results of the examples show that the supercapacitor assembled by the electrode material prepared by the application has a discharge specific capacitance of more than 260 F / g at a current density of 1 A / g, and the specific capacitance retention rate is more than 98% after 10,000 cycles. DETAILED DESCRIPTION

[0023] The application provides a preparation method of an electrode material, comprising the following steps:

[0024] (1) mixing carbon nanotubes with concentrated sulfuric acid and concentrated nitric acid for pretreatment to obtain pretreated carbon nanotubes;

[0025] (2) mixing graphene oxide with water and a reducing agent for a reduction reaction to obtain graphene;

[0026] (3) mixing the pretreated carbon nanotubes obtained in the step (1) with the graphene obtained in the step (2), a solvent, a nitrogen-containing polymer monomer and an initiator for a polymerization reaction to obtain a precursor;

[0027] (4) performing heat treatment on the precursor obtained in the step (3) to obtain an intermediate;

[0028] (5) mixing the intermediate obtained in the step (4) with an alkaline activator for activation treatment to obtain the electrode material;

[0029] The step (1) and step (2) have no time sequence.

[0030] Unless otherwise specified, the source of each raw material in the present application is not particularly limited, and commercially available products or products prepared by conventional preparation methods known to those skilled in the art can be used.

[0031] The present application mixes carbon nanotubes with concentrated sulfuric acid and concentrated nitric acid for pretreatment to obtain pretreated carbon nanotubes.

[0032] In the present application, the carbon nanotubes preferably include single-walled carbon nanotubes or multi-walled carbon nanotubes. In the present application, the diameter of the carbon nanotubes is preferably 2-30 nm, and more preferably 5-20 nm; the length of the carbon nanotubes is preferably 0.5-2 μm, and more preferably 1-1.5 μm. By limiting the length and diameter of the carbon nanotubes within the above ranges, the present application can make them better form a three-dimensional porous structure with graphene, further improving the electrochemical performance of the electrode material.

[0033] In the present application, the volume ratio of the concentrated sulfuric acid and concentrated nitric acid is preferably (2-4):1, and more preferably 3:1. The present application does not have a special limitation on the total amount of the concentrated sulfuric acid and concentrated nitric acid, which can just cover the carbon nanotubes. In the present application, the mass concentration of the concentrated sulfuric acid is preferably 98%, and the mass concentration of the concentrated nitric acid is preferably 68%. In the present application, the concentrated sulfuric acid and concentrated nitric acid have oxidizing properties, which can increase the activity of the carbon nanotubes and remove impurities, enhance the dispersibility and binding force of the carbon nanotubes, and make them form a hollow structure with open ends, absorb the volume shrinkage and expansion of the electrode material during charging, and have higher electrical conductivity, thereby improving the specific capacitance of the electrode material.

[0034] In the present application, the pretreatment is preferably carried out under stirring or ultrasonic conditions. In the present application, the stirring rate is preferably 300-600 rpm, and more preferably 500-600 rpm; the ultrasonic power is preferably 50-150 W, and more preferably 100-150 W. In the present application, the pretreatment temperature is preferably 20-100℃, and more preferably 40-80℃; the pretreatment time is preferably 0.5-10 h, and more preferably 1-6 h. By limiting the parameters of the pretreatment within the above ranges, the present application can make the carbon nanotubes form a hollow structure with open ends, have more oxygen-containing functional groups on the surface, and completely remove impurities, further improving the electrical conductivity and thereby improving the electrochemical performance of the electrode material.

[0035] After the pretreatment is completed, the present application preferably sequentially washes and dries the pretreated product to obtain pretreated carbon nanotubes.

[0036] The present application does not have special limitation to the operation of washing and drying, and the washing and drying technology known by those skilled in the art can be adopted.

[0037] The present application mixes graphene oxide with water and a reducing agent to perform a reduction reaction, and obtains graphene.

[0038] In the present application, the reducing agent is preferably L-tyrosine, hydrazine hydrate or sodium borohydride, and more preferably L-tyrosine. In the present application, the L-tyrosine is a green, non-toxic amino acid, which is safer and more environmentally friendly. When the reducing agent is L-tyrosine, the present application preferably adds a base during the reduction reaction. In the present application, the pH value of the reduction reaction system after adding the base is preferably 9-12, and more preferably 9-10. The present application does not have special limitation to the type and amount of the base, as long as the pH value of the reduction reaction system is within the above range. The present application limits the pH value of the reduction reaction system within the above range, so that the L-tyrosine has reducing property and reduces the graphene oxide into graphene.

[0039] In the present application, the mass ratio of the graphene oxide and the reducing agent is preferably (1-10):1, and more preferably (2-7):1; and the mass ratio of the graphene oxide and water is preferably 1:(30-50), and more preferably 1:40. In the present application, the temperature of the reduction reaction is preferably 30-90℃, and more preferably 40-60℃; the time of the reduction reaction is preferably 1-12h, and more preferably 2-8h; and the reduction reaction is preferably performed under stirring, and the stirring rate is preferably 400-600rpm, and more preferably 500rpm. The present application limits the amount of each raw material, the temperature and time of the reduction reaction, etc. within the above range, so that the graphene oxide is sufficiently reduced into graphene, and the conductivity of the graphene is further improved, thereby improving the electrochemical performance of the electrode material.

[0040] After the reduction reaction is completed, the present application preferably sequentially performs washing and drying on the product of the reduction reaction, and obtains graphene.

[0041] The present application does not have special limitation to the operation of washing and drying, and the washing and drying technology known by those skilled in the art can be adopted.

[0042] After obtaining the pretreated carbon nanotube and graphene, the present application performs a polymerization reaction on the pretreated carbon nanotube, graphene, solvent, nitrogen-containing polymer monomer and initiator, and obtains a precursor.

[0043] In the present application, the nitrogen-containing polymerization monomer preferably comprises pyrrole or aniline. In the present application, the nitrogen-containing polymerization monomer is polymerized under the action of an initiator on the surface of carbon nanotubes and graphene to form a core-shell structure, which can avoid the volume change of the electrode material in the charging and discharging process, and the doping of nitrogen can improve the surface polarity of the electrode material, improve the wettability of the electrolyte, facilitate the diffusion of the electrolyte, and provide lone pair electrons for nitrogen atoms to enhance the conductivity and introduce pseudo-capacitance to improve the specific capacitance of the electrode material.

[0044] In the present application, the initiator preferably comprises persulfate, and more preferably comprises ammonium persulfate or potassium persulfate. In the present application, the initiator is used to initiate the polymerization of the nitrogen-containing polymerization monomer.

[0045] In the present application, the mass ratio of the nitrogen-containing polymerization monomer and the initiator is preferably 1:(0.5-2), and more preferably 1:(1-1.5). The present application limits the mass ratio of the nitrogen-containing polymerization monomer and the initiator to the above range, which can make the monomer fully polymerize.

[0046] In the present application, the mass ratio of the pretreated carbon nanotubes, graphene and nitrogen-containing polymerization monomer is preferably (1-5):(1-5):(9-50), and more preferably (2-4):(2-4):(15-40). The present application limits the mass ratio of the pretreated carbon nanotubes, graphene and nitrogen-containing polymerization monomer to the above range, which can make the polymer generated by the polymerization reaction fully wrap the carbon nanotubes and graphene, thereby avoiding the volume change of the material in the charging and discharging process and improving the electrochemical performance of the electrode material.

[0047] In the present application, the solvent preferably comprises one or more of water and ethanol. In the present application, when the solvent comprises water and ethanol, the volume ratio of the water and ethanol is preferably (0.5-1.5):1, and more preferably 1:1. In the present application, the mass ratio of the graphene and the solvent is preferably 1:(50-80), and more preferably 1:(60-70). The present application limits the mass ratio of the graphene and the solvent to the above range, which can make the components more fully dispersed, which is conducive to the reaction.

[0048] In the present application, the mixing of the pretreated carbon nanotubes, graphene, solvent, nitrogen-containing polymerization monomer and initiator is preferably: mixing the pretreated carbon nanotubes, graphene, nitrogen-containing polymerization monomer and part of the solvent to obtain a mixed solution A, mixing the initiator with the remaining part of the solvent to obtain a mixed solution B, and then adding the mixed solution B to the mixed solution A under stirring. The present application prepares the oxidizing agent into an oxidizing agent solvent, and then performs dropwise addition, which is conducive to the smooth progress of the polymerization reaction.

[0049] In the present application, the temperature of the polymerization reaction is preferably 0-5 DEG C, more preferably 0-3 DEG C; the time of the reaction is preferably 1-24 h, more preferably 5-20 h. In the present application, the polymerization reaction is preferably carried out in an inert atmosphere. In the present application, during the polymerization reaction, the carbon nanotubes and graphene are combined and overlapped with each other by intermolecular forces and the like to form a porous structure material, which is beneficial to the transmission of electrolyte, and the monomer is polymerized on the surface of the two to form a polymer. The present application limits the temperature and time of the polymerization reaction in the above range, which can make the polymerization reaction proceed sufficiently and stably.

[0050] After the polymerization reaction is completed, the product of the polymerization reaction is preferably sequentially washed and dried to obtain a precursor in the present application.

[0051] The operation of washing and drying in the present application is not specially limited, and the technical solution of washing and drying well known to those skilled in the art can be adopted.

[0052] After the precursor is obtained, the precursor is heat-treated to obtain an intermediate in the present application.

[0053] In the present application, the temperature of the heat treatment is preferably 500-1000 DEG C, more preferably 500-800 DEG C; the time of the heat treatment is preferably 1-5 h, more preferably 2-4 h. In the present application, during the heat treatment, the polymer is carbonized to form a nitrogen-containing carbon material. The present application limits the temperature and time of the heat treatment in the above range, which can make the precursor carbonize sufficiently and have a higher nitrogen content, and further improve the electrochemical performance of the electrode material.

[0054] After the intermediate is obtained, the intermediate is mixed with an alkaline activator to perform an activation treatment, and an electrode material is obtained in the present application.

[0055] In the present application, the alkaline activator preferably includes one or more of potassium hydroxide, sodium hydroxide, potassium carbonate and sodium carbonate; the mass ratio of the intermediate to the alkaline activator is preferably 1:(1-5), more preferably 1:(2-3); the temperature of the activation treatment is preferably 500-800 DEG C, more preferably 600-700 DEG C; the time of the activation treatment is preferably 0.1-2 h, more preferably 1-1.5 h. In the present application, during the activation treatment, the activator activates the intermediate to form a rich porous structure on the surface of the carbon material, increase the specific surface area of the carbon material, and improve the electrochemical performance thereof. The present application limits the amount of the activator, the temperature and time of the activation reaction and the like in the above range, which can improve the pore structure of the carbon material and further increase the specific surface area thereof.

[0056] After the activation treatment is completed, the product of the activation treatment is preferably sequentially cooled, soaked in acid, washed with water and dried to obtain an electrode material in the present application.

[0057] The present application does not have special limitation to the operation of the cooling, water washing and drying, and the technical solution of the cooling, water washing and drying well known to the person skilled in the art can be adopted.

[0058] In the present application, the acid in the acid soaking is preferably hydrochloric acid, the mass concentration of the hydrochloric acid is preferably 5-10%, more preferably 8-10%, and the acid soaking time is preferably 1-12h, more preferably 2-8h. In the present application, the acid soaking can remove the impurities in the channel after the activation treatment, and can also produce a certain corrosion effect on the activation product, further increasing the pore structure.

[0059] The present application provides the electrode material prepared by the preparation method.

[0060] The supercapacitor assembled by the electrode material has higher specific capacitance.

[0061] The present application also provides the application of the electrode material in the supercapacitor.

[0062] The present application does not have special limitation to the operation of the electrode material in the supercapacitor, and the technical solution of the electrode material in the supercapacitor well known to the person skilled in the art can be adopted.

[0063] The technical solutions in the present application will be clearly and completely described below by combining with the embodiments in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by the person skilled in the art without creative labor belong to the protection scope of the present application.

[0064] Embodiment 1

[0065] (1) The single-walled carbon nanotubes (diameter 5-20nm, length 1-1.5μm) are mixed with 98% concentrated sulfuric acid and 68% concentrated nitric acid (the volume ratio of the concentrated sulfuric acid and the concentrated nitric acid is 3:1, and the total amount of the concentrated sulfuric acid and the concentrated nitric acid can be just enough to cover the carbon nanotubes), and ultrasonic pretreatment is carried out at 100W and 50℃ for 3h, and then the pretreated carbon nanotubes are obtained after washing and drying;

[0066] (2) The graphene oxide is mixed with water (the mass ratio of the graphene oxide and the water is 1:40), sodium hydroxide is added to adjust the pH value to 10, then the reducing agent L-tyrosine (the mass ratio of the graphene oxide and the L-tyrosine is 5:1) is added, and the reduction reaction is carried out at 500rpm and 50℃ for 3h, and then the graphene is obtained after washing and drying;

[0067] (3) mixing the pretreated carbon nanotubes, graphene, water, ethanol and pyrrole monomer to obtain a mixed solution A, mixing ammonium persulfate and water to obtain a mixed solution B, adding the mixed solution B into the mixed solution A under the condition of 0°C and 500 rpm stirring (the mass ratio of the pretreated carbon nanotubes, graphene and pyrrole monomer is 2:3:12, the amount-of-substance ratio of pyrrole monomer and ammonium persulfate is 1:1, the total mass ratio of graphene and two parts of water and ethanol is 1:70, and the total volume ratio of water and ethanol in the mixed system is 1:1), carrying out polymerization reaction for 5 h, washing and drying to obtain a precursor;

[0068] (4) treating the precursor at 500°C for 2 h, cooling to obtain an intermediate;

[0069] (5) mixing the intermediate with KOH (the mass ratio of the intermediate and KOH is 1:2), reacting at 500°C for 1 h, cooling to room temperature, immersing in 10% hydrochloric acid for 2 h, then washing with water and drying to obtain an electrode material.

[0070] Example 2

[0071] (1) mixing single-walled carbon nanotubes (diameter 5-20 nm, length 1-1.5 μm) with 98% concentrated sulfuric acid and 68% concentrated nitric acid (the volume ratio of concentrated sulfuric acid and concentrated nitric acid is 3:1, and the total amount of concentrated sulfuric acid and concentrated nitric acid can just cover the carbon nanotubes), carrying out ultrasonic pretreatment at 100 W and 50°C for 3 h, washing and drying to obtain pretreated carbon nanotubes;

[0072] (2) mixing graphene oxide with water (the mass ratio of graphene oxide and water is 1:40), adding sodium hydroxide to adjust the pH value to 10, then adding a reducing agent L-tyrosine (the mass ratio of graphene oxide and L-tyrosine is 5:1), carrying out reduction reaction at 500 rpm and 50°C for 3 h, washing and drying to obtain graphene;

[0073] (3) mixing the pretreated carbon nanotubes, graphene, water, ethanol and pyrrole monomer to obtain a mixed solution A, mixing ammonium persulfate and water to obtain a mixed solution B, adding the mixed solution B into the mixed solution A under the condition of 0°C and 500 rpm stirring (the mass ratio of the pretreated carbon nanotubes, graphene and pyrrole monomer is 3:3:15, the amount-of-substance ratio of pyrrole monomer and ammonium persulfate is 1:1, the total mass ratio of graphene and two parts of water and ethanol is 1:70, and the total volume ratio of water and ethanol in the mixed system is 1:1), carrying out polymerization reaction for 5 h, washing and drying to obtain a precursor;

[0074] (4) treating the precursor at 650°C for 2 h, cooling to obtain an intermediate;

[0075] (5) mixing the intermediate with KOH (mass ratio of intermediate to KOH is 1:2), reacting at 600 DEG C for 1h, after cooling to room temperature, soaking in 10% hydrochloric acid for 3h, then washing with water and drying to obtain the electrode material.

[0076] Application example

[0077] The electrode material prepared in Example 1 and Example 2 is mixed with conductive acetylene black and PTFE in a mass ratio of 88:6:6 respectively, and then grinded and added with ethanol to prepare a slurry, which is coated on a foamed nickel, dried, and pressed into a film by a tablet press to prepare an electrode sheet. Two electrode sheets are separated by a separator, placed in a button cell shell, and added with 1 mol / L sulfuric acid as an electrolyte to package into a supercapacitor.

[0078] The specific capacitance of the supercapacitor in the application example at a current density of 1A / g and the specific capacitance after 10000 cycles are tested. The specific capacitance of the supercapacitor assembled by the electrode material prepared in Example 1 at a current density of 1A / g is 268F / g, and the specific capacitance retention rate after 10000 cycles is 98%. The specific capacitance of the supercapacitor assembled by the electrode material prepared in Example 2 at a current density of 1A / g is 276F / g, and the specific capacitance retention rate after 10000 cycles is 98.9%. It can be seen that the supercapacitor assembled by the electrode material prepared in the application has a higher specific capacitance.

[0079] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing an electrode material, comprising the following steps: (1) Carbon nanotubes were pretreated by mixing them with concentrated sulfuric acid and concentrated nitric acid to obtain pretreated carbon nanotubes; The volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1; the pretreatment temperature is 50°C, and the pretreatment time is 3 hours; the pretreatment is carried out under ultrasonic conditions, and the ultrasonic power is 100W. (2) Graphene oxide is mixed with water and a reducing agent to carry out a reduction reaction to obtain graphene; (3) The pretreated carbon nanotubes obtained in step (1) are mixed with the graphene, solvent, nitrogen-containing polymerizable monomer and initiator obtained in step (2) to carry out a polymerization reaction to obtain a precursor; the mass ratio of the pretreated carbon nanotubes, graphene and nitrogen-containing polymerizable monomer is 3:3:15; the nitrogen-containing polymerizable monomer is pyrrole; the molar ratio of the nitrogen-containing polymerizable monomer and the initiator is 1:1; the solvent is water and ethanol; the volume ratio of water and ethanol is 1:

1. (4) The precursor obtained in step (3) is subjected to heat treatment to obtain an intermediate; the heat treatment temperature is 500~1000℃ and the heat treatment time is 1~5h. (5) The intermediate obtained in step (4) is mixed with an alkaline activator and activated to obtain an electrode material; the activation temperature is 500~800℃ and the activation time is 0.1~2h. The steps (1) and (2) are not in any particular order; the electrode material is used in the supercapacitor.

2. The preparation method according to claim 1, characterized in that, The alkaline activator in step (5) includes one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, and sodium carbonate.

3. The preparation method according to claim 1, characterized in that, In step (5), the mass ratio of the intermediate to the alkaline activator is 1:(1~5).

4. The electrode material prepared by the preparation method according to any one of claims 1 to 3 includes graphene and carbon nanotubes, and pyrolytic nitrogen-doped carbon loaded on the graphene and carbon nanotubes, wherein the pyrolytic nitrogen-doped carbon is obtained by pyrolytic activation of a nitrogen-containing polymer.

5. The application of the electrode material of claim 4 in a supercapacitor.