Carbon-based energy storage electrode material, preparation method thereof, supercapacitor and application thereof

Abstract

This invention provides carbon-based energy storage electrode materials, their preparation methods, supercapacitors, and applications. The preparation method includes: mixing aluminum borate and a raw material hydroxide in water to form a first system, performing a first hydrothermal reaction to obtain a first intermediate product; mixing the first intermediate product with an organic acid in a mixed solvent to form a second system, performing a second hydrothermal reaction to obtain a second intermediate product; mixing the second intermediate product with a carbon source and a pore-regulating agent in an organic solvent to form a third system, removing the solvent to obtain a composite precursor; and then reacting the composite precursor with N2O. 2 and CO 2 The carbon / inorganic composite material is obtained by heat treatment in a mixed atmosphere; the carbon / inorganic composite material is then acid-washed, filtered, washed, and dried to obtain a carbon-based energy storage electrode material. This invention also provides the carbon-based energy storage electrode material obtained by the above preparation method, as well as a supercapacitor and its applications. This carbon-based energy storage electrode material has a layered morphology, a well-developed hierarchical porous structure, and excellent conductivity.

Description

Carbon-based energy storage electrode materials, their preparation methods, and supercapacitors and their applications Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a carbon-based energy storage electrode material, its preparation method, and a supercapacitor and its applications. Background Technology

[0002] Porous carbon materials, due to their high specific surface area, excellent electrical conductivity, tunable structure, and good chemical stability, have broad application prospects in electrochemical energy storage, catalysis, environmental remediation, and biomedicine. With the continuous development of industrial technology and the increasing demands of applications, higher requirements are being placed on the structure and performance of high-performance porous carbon materials, especially in the field of electrochemical energy storage, where there is a need to develop novel carbon materials with high specific surface area, well-developed hierarchical pore structures, and excellent electrical conductivity.

[0003] Currently, the morphologies of porous carbon materials mainly include powder, spheres, fibers, and rods, while layered porous carbon materials have attracted much attention due to their unique two-dimensional structure and excellent mass transport properties. Layered structures possess a high specific surface area and a short diffusion path, which facilitates rapid penetration of electrolytes and gases and efficient molecular adsorption, exhibiting unique advantages in fields such as supercapacitors, lithium-sulfur batteries, and gas adsorption and separation.

[0004] Traditional methods for preparing porous carbon materials mainly include physical activation, chemical activation, template methods, and self-assembly methods. Physical activation uses CO2, water vapor, or other oxidants to activate carbon precursors at high temperatures, forming porous structures. Chemical activation uses chemical reagents such as KOH, ZnCl2, and H3PO4 to react with carbon precursors at high temperatures, forming porous structures. Template methods use inorganic or organic templates to construct spatial structures, with the carbon precursor forming a carbon skeleton inside the template; removing the template yields the porous carbon material. Self-assembly methods utilize the self-assembly behavior of organic molecules or polymers, controlling intermolecular interactions to form ordered structures, which are then carbonized to obtain porous carbon materials.

[0005] Existing methods for preparing porous carbon materials have the following problems:

[0006] 1. Most existing layered porous carbon materials are mainly micropores and lack well-developed mesoporous structures, which is not conducive to the rapid transport of substances, especially the electrochemical performance deteriorates significantly under high current density.

[0007] 2. The insufficient conductivity of carbon materials hinders interlayer electron transport, affecting their performance in electrochemical energy storage devices;

[0008] 3. It is difficult to control the layered morphology and hierarchical pore structure of the material simultaneously during the preparation process, especially during high-temperature carbonization, structural collapse is prone to occur;

[0009] 4. The preparation method is complicated, the conditions are harsh, and the cost is high, making it difficult to achieve industrial production;

[0010] 5. Layered and hierarchical porous structures are difficult to maintain and are prone to collapse; or, the prepared layered porous carbon materials have poor mechanical strength or are easily broken during electrode preparation and use, affecting practical application performance.

[0011] Therefore, it is necessary to address the problems of underdeveloped pore structure and poor conductivity in traditional layered carbon electrode materials, and to develop a simple and efficient method to prepare carbon materials that combine regular layered morphology, well-developed hierarchical pore structure and excellent conductivity. This is of great significance for improving their performance in electrochemical energy storage and other fields. Summary of the Invention

[0012] To overcome the above problems, the present invention aims to provide a carbon-based energy storage electrode material, its preparation method, and its application in supercapacitors. This carbon-based energy storage electrode material possesses a regular layered morphology, a well-developed hierarchical porous structure, and excellent conductivity. When applied to energy storage devices such as supercapacitors, it exhibits excellent electron / ion transport and electrochemical performance, and demonstrates high capacity, rate performance, and cycle performance.

[0013] To achieve the above objectives, the present invention provides a method for preparing a carbon-based energy storage electrode material, the method comprising:

[0014] S1. Aluminum borate and raw material hydroxide are mixed in water to form a first system, and a first hydrothermal reaction is carried out to obtain a first intermediate product;

[0015] S2. The first intermediate product and the organic acid are mixed in a mixed solvent to form a second system, and a second hydrothermal reaction is carried out to obtain the second intermediate product.

[0016] S3. The second intermediate product is mixed with a carbon source and a pore regulator in an organic solvent to form a third system. The solvent is removed to obtain a composite precursor.

[0017] S4. The composite precursor is heat-treated in a mixed atmosphere of N2 and CO2 to obtain a carbon / inorganic composite material.

[0018] S5. The carbon / inorganic composite material is acid-washed, then filtered, washed, and dried to obtain the carbon-based energy storage electrode material.

[0019] In the above preparation method, in S1, the molar ratio of aluminum borate to raw material hydroxide is 1:1-5; the raw material hydroxide includes at least aluminum hydroxide.

[0020] In the above preparation method, in S1, the temperature of the first hydrothermal reaction is 80-120℃, and the time of the first hydrothermal reaction is 6-24h.

[0021] In the above preparation method, in S1, the pH value of the first system is 8.0-10.0.

[0022] In the above preparation method, in S1, the raw material hydroxide further includes one or more of magnesium hydroxide, calcium hydroxide, and zinc hydroxide.

[0023] In the above preparation method, in step S2, the mass ratio of the organic acid to the first intermediate product is 0.1-0.5:1.

[0024] In the above preparation method, in S2, the organic acid includes one or more of succinic acid, citric acid, malic acid, tartaric acid, and succinic acid.

[0025] In the above preparation method, in S2, the temperature of the second hydrothermal reaction is 60-90℃, and the time of the second hydrothermal reaction is 4-12h.

[0026] In the above preparation method, in step S3, the mass ratio of the second intermediate product to the carbon source is 1:0.2-0.8.

[0027] In the above preparation method, in step S3, the mass ratio of the pore control agent to the second intermediate product is 0.1-0.6:1.

[0028] In the above preparation method, in step S3, the carbon source includes one or more of the following: polyurethane resin, polyacrylonitrile, phenolic resin, furan resin, asphalt, petroleum coke, and heavy oil.

[0029] In the above preparation method, in step S3, the pore control agent includes one or more of urea, polymethyl methacrylate, chlorinated polyethylene fiber, and block copolymer.

[0030] In the above preparation method, in S4, the volume ratio of N2 to CO2 in the mixed atmosphere of N2 and CO2 is 4:1-9:1.

[0031] In the above preparation method, in step S4, the heat treatment includes a first heat treatment and a second heat treatment performed sequentially.

[0032] In the above preparation method, in S4, the heating rate of the first heat treatment is 3-7℃ / min, the temperature of the first heat treatment is 350-450℃, and the holding time of the first heat treatment is 2-4h.

[0033] In the above preparation method, in S4, the heating rate of the second heat treatment is 4-8℃ / min, the temperature of the second heat treatment is 750-900℃, and the holding time of the second heat treatment is 2-5h.

[0034] In the above preparation method, step S5 further includes nitrogen doping of the dried product.

[0035] In the above preparation method, the nitrogen doping process includes: heat-treating the dried product in a nitrogen-containing gas to complete the nitrogen doping. The heat treatment temperature is 500-700℃, and the holding time is 0.5-2 hours.

[0036] In the above preparation method, the flow rate of the nitrogen-containing gas is 50-1000 mL / min.

[0037] In the above preparation method, the nitrogen-containing gas includes one or a combination of two or more of ammonia, urea vapor, pyridine vapor, and methylamine gas.

[0038] The present invention also provides a carbon-based energy storage electrode material, which is obtained by the preparation method of the above-mentioned carbon-based energy storage electrode material provided by the present invention.

[0039] According to a specific embodiment of the present invention, the carbon-based energy storage electrode material includes two-dimensional layered hierarchical porous carbon material and / or nitrogen-doped two-dimensional layered hierarchical porous carbon material.

[0040] According to a specific embodiment of the present invention, the carbon-based energy storage electrode material has a two-dimensional sheet morphology, and the average thickness of the carbon-based energy storage electrode material is 5-100 nm, and the lateral dimension is 0.05-10 μm.

[0041] According to a specific embodiment of the present invention, the ratio of the average thickness to the lateral dimension of the carbon-based energy storage electrode material is 0.5-2000.

[0042] According to a specific embodiment of the present invention, the carbon-based energy storage electrode material has micropores and mesopores; the pore volume of the micropores accounts for 20%-50% of the total pore volume, and the pore volume of the mesopores accounts for 50-80% of the total pore volume.

[0043] According to a specific embodiment of the present invention, the specific surface area of ​​the carbon-based energy storage electrode material is 1500-3500 m². 2 / g.

[0044] According to a specific embodiment of the present invention, the porosity of the carbon-based energy storage electrode material is 75%-90%.

[0045] According to a specific embodiment of the present invention, the total pore volume of the carbon-based energy storage electrode material is 1.5-4.0 cm³. 3 / g.

[0046] According to a specific embodiment of the present invention, the pore size distribution of the micropores and mesopores of the carbon-based energy storage electrode material is 0.5-50 nm.

[0047] The present invention also provides a supercapacitor, wherein the electrode material of the supercapacitor includes the carbon-based energy storage electrode material provided by the present invention.

[0048] This invention also provides the application of the above-mentioned carbon-based energy storage electrode material in fuel cells, lithium-ion batteries, lithium-ion capacitors, sodium-ion batteries, lithium-sulfur batteries, supercapacitors, gas adsorption and separation materials, water treatment adsorption materials, or drug carriers.

[0049] According to a specific embodiment of the present invention, the electrode material of the supercapacitor is made of or includes the aforementioned carbon-based energy storage electrode material.

[0050] According to a specific embodiment of the present invention, the electrolyte of the supercapacitor includes an aqueous electrolyte or an organic electrolyte.

[0051] The beneficial effects of this invention include:

[0052] The carbon-based energy storage electrode material provided by this invention possesses a regular layered morphology, a well-developed hierarchical porous structure, and excellent conductivity. It exhibits a large specific surface area, abundant interlayer porosity, and excellent electron / ion transport performance, and its preparation method is simple and efficient. This carbon material can be widely used in electrochemical energy storage and conversion, catalysis, gas adsorption and separation, water treatment, and drug delivery. Energy storage devices made from this material demonstrate excellent electrochemical characteristics in terms of capacity performance, rate performance, and cycle performance, showing promising application results in the field of electrochemical energy storage. Attached Figure Description

[0053] Figure 1 is a scanning electron microscope image of the second intermediate product prepared in Example 1.

[0054] Figure 2 is a scanning electron microscope image of the carbon-based energy storage electrode material of Example 1.

[0055] Figure 3 is a transmission electron microscope image of the carbon-based energy storage electrode material of Example 1.

[0056] Figure 4 shows the pore size distribution curve of the carbon-based energy storage electrode material in Example 1.

[0057] Figure 5 shows the cyclic voltammetry curve of the supercapacitor made of the carbon-based energy storage electrode material of Example 1.

[0058] Figure 6 shows the rate performance curve of the supercapacitor made of the carbon-based energy storage electrode material of Example 1. Detailed Implementation

[0059] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0060] According to a specific embodiment of the present invention, the present invention provides a method for preparing a carbon-based energy storage electrode material, the method comprising:

[0061] S1. Aluminum borate and raw material hydroxide are mixed in water to form a first system, and a first hydrothermal reaction is carried out to obtain a first intermediate product;

[0062] S2. The first intermediate product and the organic acid are mixed in a mixed solvent to form a second system, and a second hydrothermal reaction is carried out to obtain the second intermediate product.

[0063] S3. The second intermediate product is mixed with a carbon source and a pore regulator in an organic solvent to form a third system. The solvent is removed to obtain a composite precursor.

[0064] S4. The composite precursor is heat-treated in a mixed atmosphere of N2 and CO2 to obtain a carbon / inorganic composite material.

[0065] S5. The carbon / inorganic composite material is acid-washed, then filtered, washed, and dried to obtain the carbon-based energy storage electrode material.

[0066] In the above preparation method, in S1, the molar ratio of aluminum borate to the raw material hydroxide is 1:1-5, for example, specific values ​​such as 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, etc., and a range with any two of the above specific values ​​as endpoints, and can further be 1:1-2.

[0067] In the above preparation method, in S1, the chemical formula of the aluminum borate can be H3AlBO2.

[0068] In the above preparation method, in step S1, the raw material hydroxide includes at least aluminum hydroxide. The aluminum hydroxide is an amphoteric hydroxide, and it can react with aluminum borate to form a layered first intermediate product.

[0069] Furthermore, the raw material hydroxide also includes one or more of magnesium hydroxide, calcium hydroxide, and zinc hydroxide. That is, the raw material hydroxide may include a combination of at least one of magnesium hydroxide, calcium hydroxide, and zinc hydroxide and aluminum hydroxide.

[0070] In the above preparation method, in S1, the temperature of the first hydrothermal reaction is 80-120℃, for example, specific values ​​such as 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, etc., and a range with any two of the above specific values ​​as endpoints. The time of the first hydrothermal reaction is 6-24h, for example, specific values ​​such as 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, etc., and a range with any two of the above specific values ​​as endpoints. Further, the temperature of the first hydrothermal reaction can be 90-110℃, and the time of the first hydrothermal reaction is 12-18h.

[0071] In the above preparation method, in S1, the mass concentration of the solute in the first system can be 9-50%, specifically 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, for example 9-16% or 30-50%. The amount of water added to the first system can be determined according to the mass concentration of the solute.

[0072] In the above preparation method, in S1, the pH value of the first system is 8.0-10.0, for example, specific values ​​such as 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, and a range with any two of the above specific values ​​as endpoints, for example, it can be 8.5-9.5.

[0073] In the above preparation method, in S1, the first intermediate product can be a layered precursor. Further, the first intermediate product can be a layered hydroxide containing at least boron and aluminum. Even further, the chemical composition of the layered hydroxide can be: M x Al 1-x (OH)2B y·nH₂O, wherein M is at least one of Mg, Ca, and Zn, x is 0-0.8, y is 0.05-0.5, and n is 0.5-5. y can be specific values ​​such as 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, or a range with any two of these specific values ​​as endpoints; n can be specific values ​​such as 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, or a range with any two of these specific values ​​as endpoints. In some specific embodiments, when the layered hydroxide contains element M, x can be 0.2-0.8, for example, specific values ​​such as 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or a range with any two of these specific values ​​as endpoints.

[0074] In the above preparation method, S2 is an intercalation treatment of the layered first intermediate product using organic acid, which helps to generate mesoporous structures during subsequent heat treatment.

[0075] In the above preparation method, in S2, the organic acid includes one or more of succinic acid, citric acid, malic acid, tartaric acid, and succinic acid.

[0076] In the above preparation method, in S2, the mass ratio of the organic acid to the first intermediate product is 0.1-0.5:1, for example, specific values ​​such as 0.1:1, 0.15:1, 0.20:1, 0.25:1, 0.30:1, 0.35:1, 0.40:1, 0.45:1, 0.50:1, etc., and a range with any two of the above specific values ​​as endpoints, and can further be 0.2-0.3:1.

[0077] In the above preparation method, in step S2, the second hydrothermal reaction is used to intercalate the first intermediate product. The temperature of the second hydrothermal reaction is 60-90°C, for example, specific values ​​such as 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, and 90°C, and a range with any two of the above specific values ​​as endpoints; the time of the second hydrothermal reaction is 4-12 hours, for example, specific values ​​such as 4 hours, 6 hours, 8 hours, 10 hours, and 12 hours, and a range with any two of the above specific values ​​as endpoints. Further, the temperature of the second hydrothermal reaction can be 65-80°C, and the time of the second hydrothermal reaction can be 6-12 hours.

[0078] In the above preparation method, in step S2, the mixed solvent is used to disperse the first intermediate product. Specifically, the mixed solvent may include water and ethanol. In some specific embodiments, the volume ratio of ethanol to water in the mixed solvent is 1-4:1-4.

[0079] In the above preparation method, in step S2, the amount of the mixed solvent is sufficient to ensure that the first intermediate product is uniformly dispersed in the second system. This invention does not impose any special limitations on the amount of the mixed solvent. In some specific embodiments, the volume ratio of the mixed solvent to the mass of the first intermediate product is 60-90 mL: 2-3 g.

[0080] In some specific implementations, the second intermediate product obtained in S2 may have a layered morphology. Specifically, the second intermediate product may be a layered precursor for organic acid intercalation.

[0081] In the above preparation method, S3 mixes the second intermediate product with a carbon source and a pore control agent to obtain a composite precursor, which can be used to prepare subsequent hierarchical porous carbon materials.

[0082] In the above preparation method, in step S3, the carbon source includes one or more of the following: polyurethane resin, polyacrylonitrile, phenolic resin, furan resin, asphalt, petroleum coke, and heavy oil.

[0083] In some specific embodiments, the polyurethane resin has a number-average molecular weight of 5,000-50,000 or a weight-average molecular weight of 10,000-100,000.

[0084] In the above preparation method, in S3, the mass ratio of the second intermediate product to the carbon source is 1:0.2-0.8, for example, specific values ​​such as 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, 1:0.55, 1:0.6, 1:0.65, 1:0.7, 1:0.75, 1:0.8, etc., and a range with any two of the above specific values ​​as endpoints, for example, it can be 1:0.2-0.75.

[0085] In the above preparation method, in step S3, the pore control agent can decompose into gas during subsequent high-temperature heat treatment, which can further etch the carbon source and achieve pore regulation. Specifically, the pore control agent can decompose into gas during subsequent high-temperature treatment. These gases can act as a "gas foaming agent" during carbonization. These gases form bubbles in the precursor and leave honeycomb-like mesopores (pore size 2-50 nm). Furthermore, the gas can produce a slight oxidative etching effect on the carbon framework, expanding the existing small pores to form mesopores.

[0086] In the above preparation method, in S3, the pore control agent may include one or more of urea, polymethyl methacrylate, chlorinated polyethylene fiber, block copolymers, etc. In some specific embodiments, the block copolymer may include a pyrolytic block copolymer, which includes F127 and / or P123. The urea can promote mesopore formation, specifically through the following pathways: (1) Thermal decomposition to generate active gases: Urea decomposes into gases such as NH3 and CO2 under heating conditions (>150℃), which act as "in-situ foaming agents" during carbonization. When the gas escapes, it forms bubbles in the carbon precursor, leaving honeycomb-like mesopores (2–50 nm); the gas slightly oxidizes and etches the carbon skeleton, expanding existing pores to form mesopores. (2) Inhibit carbonization shrinkage: The nitrogen-containing free radicals generated by urea decomposition can crosslink carbon precursor molecules, enhance the rigidity of the skeleton, reduce the volume shrinkage during high-temperature carbonization, and thus retain more mesoporous structures.

[0087] In the above preparation method, in S3, the mass ratio of the pore regulator to the second intermediate product is 0.1-0.6:1, for example, specific values ​​such as 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, etc., and a range with any two of the above specific values ​​as endpoints, and can further be 0.2-0.4:1 or 0.25-0.4:1.

[0088] In the above preparation method, in step S3, the organic solvent includes one or a combination of two or more of N,N-dimethylformamide (DMF), tetrahydrofuran, and acetone.

[0089] In the above preparation method, in S3, in the third system, the mass of the organic solvent is 5-20 times the total mass of the solute (second intermediate product, carbon source, pore regulator, which can be solid), for example, 8-12 times.

[0090] In the above preparation method, step S3, the solvent removal may specifically include a process of sequential evaporation and drying. The evaporation temperature is 60-90℃, for example, specific values ​​such as 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, etc., and a range with any two of the above specific values ​​as endpoints. The evaporation process may be accompanied by stirring; the evaporation may be stopped when the third system becomes viscous. The drying temperature is 80-120℃, for example, specific values ​​such as 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, etc., and a range with any two of the above specific values ​​as endpoints. The drying time is 4-12 h, for example, specific values ​​such as 4h, 6h, 8h, 10h, 12h, etc., and a range with any two of the above specific values ​​as endpoints.

[0091] In the above preparation method, carbonization can be achieved through heat treatment in step S4, which can form micropores and mesopores. In some specific embodiments, the carbon / inorganic composite material obtained in step S4 can have a layered morphology.

[0092] In the above preparation method, in S4, the volume ratio of N2 to CO2 in the mixed atmosphere of N2 and CO2 is 4:1-9:1, for example, specific values ​​such as 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, etc., and a range with any two of the above specific values ​​as endpoints, and can further be 6:1-9:1.

[0093] In the above preparation method, in S4, the heat treatment is a step-by-step heat treatment, specifically a two-stage heat treatment. Compared with a one-stage heat treatment, the two-stage heat treatment has the following advantages: (1) it can achieve more thorough removal of volatiles and the formation of a stable carbon skeleton; (2) it has higher activation efficiency and selectivity; (3) the two-stage method separates two different chemical transformation processes, allowing for independent optimization of each stage; (4) the process has good flexibility and operability.

[0094] In the above preparation method, in step S4, the heat treatment includes a first heat treatment and a second heat treatment performed sequentially.

[0095] In the above preparation method, in S4, the heating rate of the first heat treatment is 3-7 °C / min, for example, specific values ​​such as 3 °C / min, 3.5 °C / min, 4 °C / min, 4.5 °C / min, 5 °C / min, 5.5 °C / min, 6 °C / min, 6.5 °C / min, 7 °C / min, and a range with any two of the above specific values ​​as endpoints; the temperature of the first heat treatment is 350-450 °C, for example, specific values ​​such as 350 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C, 410 °C, 420 °C, 430 °C, 440 °C, 450 °C, and a range with any two of the above specific values ​​as endpoints; the holding time of the first heat treatment is 2-4 h, for example, specific values ​​such as 2 h, 2.5 h, 3 h, 3.5 h, 4 h, and a range with any two of the above specific values ​​as endpoints. Furthermore, the heating rate of the first heat treatment can be 4-6℃ / min, the temperature can be 380-450℃, and the holding time can be 2-3h.

[0096] In the above preparation method, in step S4, the heating rate of the second heat treatment is 4-8℃ / min, for example, specific values ​​such as 4℃ / min, 4.5℃ / min, 5℃ / min, 5.5℃ / min, 6℃ / min, 6.5℃ / min, 7℃ / min, 7.5℃ / min, 8℃ / min, and any two of the above specific values ​​as endpoints; the temperature of the second heat treatment is 750-900℃, for example, specific values ​​such as 700℃, 750℃, 800℃, 850℃, 900℃, and any two of the above specific values ​​as endpoints; the holding time of the second heat treatment is 2-5h, for example, specific values ​​such as 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, and any two of the above specific values ​​as endpoints. Further, the heating rate of the second heat treatment can be 5-7℃ / min, the temperature can be 800-900℃, and the holding time can be 2-4h.

[0097] In the above preparation method, the first heat treatment at 350-450℃ serves as a pre-carbonization process, transforming the unstable, volatile-containing composite precursor into a pre-stable, carbon-rich framework structure. This stable framework forms the basis for subsequent successful high-temperature carbonization and efficient, controllable activation pore formation. The second heat treatment at 750-900℃ complements the pre-carbonization of the first heat treatment, jointly achieving precise control of the porous carbon material structure and performance enhancement. The second heat treatment further deepens the pore formation of the carbon material, improving its purity, conductivity, and chemical stability.

[0098] In the above preparation method, in S4, the gas flow rate for heat treatment is 100-500 mL / min, for example, specific values ​​such as 100 mL / min, 150 mL / min, 200 mL / min, 250 mL / min, 300 mL / min, 350 mL / min, 400 mL / min, 450 mL / min, 500 mL / min, etc., and a range with any two of the above specific values ​​as endpoints, and can further be 150-300 mL / min.

[0099] In the above preparation method, in S4, the gas pressure inside the heat treatment pipe is 0.5-2.0 atmospheres, for example, specific values ​​such as 0.5 atmospheres, 1 atmosphere, 1.5 atmospheres, 2 atmospheres, etc., and a range with any two of the above specific values ​​as endpoints.

[0100] In the above preparation method, the formation of micropores in the carbon-based energy storage electrode material is related to the carbonization process of S4; the formation of mesopores in the carbon-based energy storage electrode material is related to the organic acid intercalation treatment of S2, the addition of pore control agent, and the heat treatment of S4 in a specific atmosphere.

[0101] In the above preparation method, in step S5, acid washing can remove metal elements from the material, thereby purifying the hierarchical porous carbon material.

[0102] In the above preparation method, in step S5, the pickling is performed using an inorganic acid, which may specifically include one or more of sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid.

[0103] In the above preparation method, in step S5, the concentration of the inorganic acid is 0.1-1.0 mol / L, for example, specific values ​​such as 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, etc., and a range with any two of the above specific values ​​as endpoints, and can further be 0.3-0.6 mol / L.

[0104] In the above preparation method, in step S5, the pickling temperature is 50-80℃, for example, specific values ​​such as 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, and any two of the above specific values ​​as endpoints; the pickling time is 8-24h, for example, specific values ​​such as 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, and any two of the above specific values ​​as endpoints. Further, the pickling temperature can be 60-75℃, and the pickling time can be 14-20h.

[0105] In the above preparation method, in step S5, the washing can specifically be washing with water until neutral.

[0106] In the above preparation method, in step S5, the drying temperature is 100-120℃, for example, specific values ​​such as 100℃, 105℃, 110℃, 115℃, 120℃, etc., and a range with any two of the above specific values ​​as endpoints; the drying time is 8-12h, for example, specific values ​​such as 8h, 9h, 10h, 11h, 12h, etc., and a range with any two of the above specific values ​​as endpoints.

[0107] In the above preparation method, in step S5, the dried product can be a layered carbon material with a hierarchical porous structure.

[0108] In the above preparation method, step S5 may further include nitrogen doping of the dried product. Nitrogen doping introduces nitrogen-containing functional groups into the material, increasing the hydrophilicity of the carbon-based energy storage electrode material and further improving its electrochemical performance.

[0109] In the above preparation method, in step S5, the nitrogen doping process includes: heat-treating the dried product (a carbon / inorganic composite material that has been acid-washed, filtered, washed, and dried) in a nitrogen-containing gas to complete the nitrogen doping.

[0110] In the above preparation method, the temperature of the heat treatment of the nitrogen doping process is 500-700℃, for example, specific values ​​such as 500℃, 550℃, 600℃, 650℃, 700℃, etc., and a range with any two of the above specific values ​​as endpoints, and can be further 550-650℃.

[0111] In the above preparation method, the heat treatment holding time of the nitrogen doping process is 0.5-2h, for example, specific values ​​such as 0.5h, 1h, 1.5h, 2h, etc., and a range with any two of the above specific values ​​as endpoints, and can be further 0.5-1.5h.

[0112] In some specific embodiments, during the nitrogen doping process, the flow rate of the nitrogen-containing gas can be 50-1000 mL / min, for example, 50 mL / min, 100 mL / min, 150 mL / min, 200 mL / min, 500 mL / min, 1000 mL / min, etc., and a range with any two of the above specific values ​​as endpoints, for example, 100-250 mL / min.

[0113] Furthermore, the nitrogen doping may also include cooling the heat-treated product to room temperature, wherein the cooling can be natural cooling or the cooling rate can be controlled to be 5-10°C / min.

[0114] In the above preparation method, in step S5, the nitrogen-containing gas includes one or a combination of two or more of ammonia, urea vapor, pyridine vapor, and methylamine gas.

[0115] According to a specific embodiment of the present invention, the preparation method of the carbon-based energy storage electrode material includes:

[0116] S1. Mix aluminum borate and raw material hydroxide (containing at least aluminum hydroxide) in water at a molar ratio of 1:1-5 to form a solution. Adjust the pH of the solution to 8.0-10.0 to form the first system. React the solution hydrothermally at 80-120℃ for 6-24 hours to obtain the first intermediate product.

[0117] S2. The organic acid with a mass ratio of 0.1-0.5:1 and the first intermediate product are uniformly dispersed in a mixed solvent to form a second system. The mixed solvent includes ethanol and water with a volume ratio of 1-4:1-4. The second system is hydrothermally reacted at 60-90℃ for 4-12 hours, cooled, filtered, washed, and dried to obtain the second intermediate product.

[0118] S3. The second intermediate product is mixed with a carbon source and a pore regulator in an organic solvent to form a third system, wherein the mass ratio of the second intermediate product to the carbon source is 1:0.2-0.8, the mass ratio of the pore regulator to the second intermediate product is 0.1-0.6:1, and the mass of the solvent in the third system is 5-20 times the total mass of the solute; the solvent is removed from the third system (specifically, the third system can be stirred and evaporated at 60-90℃ until it becomes viscous, and then dried at 80-120℃ for 4-12 h) to obtain the composite precursor;

[0119] S4. In a mixed atmosphere with a volume ratio of N2 to CO2 of 4:1-9:1, maintain a gas flow rate of 100-500 mL / min and a gas pressure of 0.5-2.0 atmospheres in the pipeline. Heat the composite precursor to 350-450℃ at a rate of 3-7℃ / min for 2-4 hours, then heat it to 750-900℃ at a rate of 4-8℃ / min for 2-5 hours. Cool the mixture to obtain a carbon / inorganic composite material with a layered structure.

[0120] S5. The carbon / inorganic composite material is immersed in an inorganic acid solution with a concentration of 0.1-1.0 mol / L at 50-80°C for 8-24 hours for acid washing, filtered, washed with water until neutral, and dried (100-120°C, 8-12 hours) to obtain the carbon-based energy storage electrode material, which includes a two-dimensional layered hierarchical porous carbon material.

[0121] Preferably, step S5 further includes placing the dried product (two-dimensional layered hierarchical porous carbon material) in a tube furnace and heat-treating it at 500-700°C for 0.5-2 hours in a nitrogen-containing gas with a flow rate of 50-1000 mL / min, and then cooling it to room temperature to obtain a carbon-based energy storage electrode material, wherein the carbon-based energy storage electrode material includes nitrogen-doped two-dimensional layered hierarchical porous carbon material.

[0122] The preparation method provided by the present invention synthesizes a layered precursor (second intermediate product), which is beneficial to maintaining the layered morphology of carbon materials; by adopting a two-stage heat treatment process, the stability and strength of the carbon skeleton can be improved, thereby avoiding the collapse of the hierarchical porous structure and helping to maintain the hierarchical porous structure.

[0123] The present invention also provides a carbon-based energy storage electrode material, which is obtained by the above-mentioned preparation method of carbon-based energy storage electrode material.

[0124] According to a specific embodiment of the present invention, the carbon-based energy storage electrode material includes a two-dimensional layered hierarchical porous carbon material and / or a nitrogen-doped two-dimensional layered hierarchical porous carbon material.

[0125] According to a specific embodiment of the present invention, the carbon-based energy storage electrode material (two-dimensional layered hierarchical porous carbon material and / or nitrogen-doped two-dimensional layered hierarchical porous carbon material) has a two-dimensional sheet morphology.

[0126] According to a specific embodiment of the present invention, the average thickness of the carbon-based energy storage electrode material (two-dimensional layered multi-level porous carbon material and / or nitrogen-doped two-dimensional layered multi-level porous carbon material) is 5-100 nm, for example, specific values ​​such as 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc., and a range with any two of the above specific values ​​as endpoints.

[0127] According to a specific embodiment of the present invention, the lateral dimension of the carbon-based energy storage electrode material (two-dimensional layered multi-level porous carbon material and / or nitrogen-doped two-dimensional layered multi-level porous carbon material) is 0.05-10 μm, for example, specific values ​​such as 0.05 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc., and a range with any two of the above specific values ​​as endpoints.

[0128] In some specific embodiments, the ratio of the average thickness to the lateral dimension of the carbon-based energy storage electrode material (two-dimensional layered hierarchical porous carbon material and / or nitrogen-doped two-dimensional layered hierarchical porous carbon material) is 0.5-2000, for example, specific values ​​such as 0.5, 1, 10, 50, 100, 150, 200, 500, 1000, 1500, 2000, etc., and a range with any two of the above specific values ​​as endpoints.

[0129] According to a specific embodiment of the present invention, the carbon-based energy storage electrode material (two-dimensional layered multi-level porous carbon material and / or nitrogen-doped two-dimensional layered multi-level porous carbon material) has a well-developed multi-level porous structure inside. Specifically, the carbon-based energy storage electrode material (two-dimensional layered multi-level porous carbon material and / or nitrogen-doped two-dimensional layered multi-level porous carbon material) has micropores (pore size <2nm) and mesopores (pore size 2-50nm).

[0130] In the aforementioned carbon-based energy storage electrode material, the pore volume of the micropores accounts for 20%-50% of the total pore volume, specifically 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc., and a range with any two of the above specific values ​​as endpoints, for example, 20%-40%; the pore volume of the mesopores accounts for 50%-80% of the total pore volume, specifically 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc., and a range with any two of the above specific values ​​as endpoints, for example, 60-80%.

[0131] According to a specific embodiment of the present invention, the micropore and mesopore size distribution of the carbon-based energy storage electrode material (two-dimensional layered hierarchical porous carbon material and / or nitrogen-doped two-dimensional layered hierarchical porous carbon material) is 0.5-50 nm.

[0132] According to a specific embodiment of the present invention, the specific surface area of ​​the carbon-based energy storage electrode material (two-dimensional layered hierarchical porous carbon material and / or nitrogen-doped two-dimensional layered hierarchical porous carbon material) is 1500-3500 m². 2 / g, for example, 1500m 2 / g、2000m 2 / g、2500m 2 / g、3000m 2 / g、3500m 2 The specific values ​​such as / g and the range with any two of the above specific values ​​as endpoints can be further defined as 2500-3500m. 2 / g.

[0133] According to a specific embodiment of the present invention, the porosity of the carbon-based energy storage electrode material (two-dimensional layered multi-level porous carbon material and / or nitrogen-doped two-dimensional layered multi-level porous carbon material) is 75%-90%, for example, specific values ​​such as 75%, 80%, 85%, 90%, etc., and a range with any two of the above specific values ​​as endpoints, and can further be 80%-90%.

[0134] According to a specific embodiment of the present invention, the total pore volume of the carbon-based energy storage electrode material (two-dimensional layered hierarchical porous carbon material and / or nitrogen-doped two-dimensional layered hierarchical porous carbon material) is 1.5-4.0 cm³. 3 / g, for example, 1.5cm 3 / g, 2.0cm 3 / g, 2.5cm 3 / g, 3.0cm 3 / g, 3.5cm 3 / g, 4.0cm 3 The specific values, such as g, and the range with any two of the above specific values ​​as endpoints, can be further defined as 1.5-3.0 cm. 3 / g.

[0135] According to a specific embodiment of the present invention, when the preparation method of the carbon-based energy storage electrode material further includes a nitrogen doping process, the obtained carbon-based energy storage electrode material includes a nitrogen-doped two-dimensional layered hierarchical porous carbon material. The mass content of nitrogen in the material can be 1-10 wt%, for example, specific values ​​such as 1 wt%, 1.6 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.4 wt%, 4 wt%, 4.5 wt%, 4.8 wt%, 5.4 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.4 wt%, 8 wt%, 8.5 wt%, 9 wt%, 10 wt%, etc., and a range with any two of the above specific values ​​as endpoints, for example, 3-5 wt%.

[0136] The present invention also provides a supercapacitor, wherein the electrode material of the supercapacitor may include the carbon-based energy storage electrode material (two-dimensional layered multi-level porous carbon material and / or nitrogen-doped two-dimensional layered multi-level porous carbon material) provided by the present invention.

[0137] In some specific embodiments, the electrolyte of the supercapacitor includes an aqueous electrolyte or an organic electrolyte.

[0138] In some specific embodiments, the aqueous electrolyte includes one or more of the following: a KOH solution with a concentration of 3-7 mol / L, an H2SO4 solution with a concentration of 1-3 mol / L, and a Na2SO4 solution with a concentration of 1-3 mol / L; the organic electrolyte includes one or more of the following: a TEABF4 / PC solution, a TEABF4 / ACN solution, and a TEABF4 / PC+DME solution.

[0139] According to a specific embodiment of the present invention, a supercapacitor using the carbon-based energy storage electrode material (two-dimensional layered hierarchical porous carbon material and / or nitrogen-doped two-dimensional layered hierarchical porous carbon material) of the present invention as the electrode material has a specific capacitance of 200-400 F / g at a current density of 1 A / g, and more specifically, 280-400 F / g; the specific capacitance of the supercapacitor at a current density of 30 A / g is 180-320 F / g, and more specifically, 250-320 F / g; the capacitance ratio of the supercapacitor at a current density of 30-50 A / g is 80%-90%, and more specifically, 86-90%; the capacitance retention rate of the supercapacitor after 50,000 cycles at a current density of 5 A / g is ≥99%, and more specifically, ≥99.7%, and even more specifically, ≥99.8%.

[0140] The present invention also provides the application of the above-mentioned carbon-based energy storage electrode materials (including two-dimensional layered hierarchical porous carbon materials and / or nitrogen-doped two-dimensional layered hierarchical porous carbon materials) in fuel cells, lithium-ion batteries, lithium-ion capacitors, sodium-ion batteries, lithium-sulfur batteries, fuel cell catalyst supports, gas adsorption and separation materials, water treatment adsorption materials or drug carriers.

[0141] In some specific implementations, the aforementioned carbon-based energy storage electrode materials (two-dimensional layered hierarchical porous carbon materials and / or nitrogen-doped two-dimensional layered hierarchical porous carbon materials) can be used as electrode materials for energy storage devices such as fuel cells, lithium-ion batteries, lithium-ion capacitors, sodium-ion batteries, lithium-sulfur batteries, and supercapacitors. These two electrode materials can also be used as catalyst supports for fuel cells.

[0142] Example 1

[0143] This embodiment provides a carbon-based energy storage electrode material and its preparation method. The preparation method of the carbon-based energy storage electrode material includes the following steps:

[0144] (1) Preparation steps of layered precursor: 6.0g aluminum borate (H3AlBO2) and 12.0g aluminum hydroxide were mixed and added to 100mL of deionized water to form a solution. The pH of the solution was adjusted to 9.0 to form the first system. The reaction was carried out at 100℃ for 12h hydrothermal reaction. After cooling, washing and drying, the layered first intermediate product was obtained.

[0145] 2.0 g of the above layered first intermediate product was dispersed in 60 mL of ethanol-water mixed solution (ethanol to water volume ratio 2:1), and 0.6 g of succinic acid (succinic acid to first intermediate product mass ratio 0.3:1) was added to form a second system. The reaction was carried out at 70 °C for 8 h, and then cooled, filtered, washed and dried to obtain the second intermediate product.

[0146] (2) Mixing and composite steps: 2.0g of the second intermediate product obtained in step (1) and 1.0g of polyurethane resin (number average molecular weight 25000) are mixed at a mass ratio of 1:0.5. 0.8g of urea (mass ratio of urea to the second intermediate product is 0.4:1) is added as a pore regulator. The above components (second intermediate product, carbon source, pore regulator) are thoroughly mixed in 40mL of N,N-dimethylformamide (DMF) to form a third system. The third system is stirred and evaporated at 70℃ until it becomes viscous, and then dried at 100℃ for 8h to obtain the composite precursor.

[0147] (3) Heat treatment steps: Place all the composite precursors obtained in step (2) in a tube furnace, and heat them to 400°C at a heating rate of 5°C / min for the first heat treatment under a mixed gas atmosphere of N2 and CO2 (the volume ratio of N2 and CO2 is 7:1 and the total flow rate is 200 mL / min). Hold for 3 h. Then heat them to 850°C at a heating rate of 6°C / min for the second heat treatment. Hold for 3 h. The gas pressure in the heat treatment pipe is 1 atmosphere. Cool naturally to room temperature to obtain layered carbon / inorganic composite material.

[0148] (4) Acid washing step: Soak all the layered carbon / inorganic composite materials obtained in step (3) in 0.5 mol / L sulfuric acid solution for 16 h at 65 °C; filter, wash with water until neutral, and dry at 110 °C for 10 h to obtain two-dimensional layered multi-level porous carbon material;

[0149] (5) Ammonia modification (nitrogen doping) step: The two-dimensional layered multi-level porous carbon material obtained in step (4) is placed in a tube furnace, and NH3 gas with a flow rate of 100 mL / min is introduced. The material is treated at 600℃ for 1 h and then cooled to room temperature at a rate of 8℃ / min to obtain a carbon-based energy storage electrode material. This carbon-based energy storage electrode material is a nitrogen-doped two-dimensional layered multi-level porous carbon material.

[0150] The first intermediate product obtained in this embodiment can be a layered precursor (specifically, a layered hydroxide containing boron and aluminum elements), and the second intermediate product can be a layered precursor intercalated with organic acids.

[0151] Figure 1 is a scanning electron microscope image of the second intermediate product (layered precursor with organic acid intercalation) prepared in this embodiment. It can be seen that the material exhibits a good regular two-dimensional layered structure.

[0152] Figure 2 is a scanning electron microscope image of the carbon-based energy storage electrode material (nitrogen-doped two-dimensional layered hierarchical porous carbon material) prepared in this embodiment. The material has a clear layered morphology, an average thickness of about 30 nm, and a lateral dimension of 5-10 μm.

[0153] Figure 3 is a transmission electron microscope (TEM) image of the carbon-based energy storage electrode material (nitrogen-doped two-dimensional layered hierarchical porous carbon material) prepared in this embodiment. As shown in Figure 3, the TEM image of the nitrogen-doped two-dimensional layered hierarchical porous carbon material shows that the edges of the nitrogen-doped two-dimensional layered hierarchical porous carbon material are composed of 1-3 carbon layers.

[0154] The specific surface area of ​​this nitrogen-doped two-dimensional layered hierarchical porous carbon material was 2650 m², as determined by nitrogen adsorption-desorption testing. 2 / g. Figure 4 shows the pore size distribution curve of the carbon-based energy storage electrode material (nitrogen-doped two-dimensional layered hierarchical porous carbon material) prepared in this embodiment. As shown in Figure 4, the pore size distribution is 0.8-30 nm, the pore volume of micropores (pore size <2 nm) accounts for 32% of the total pore volume, the pore volume of mesopores (pore size 2-50 nm) accounts for 68% of the total pore volume, and the total pore volume is 1.95 cm³. 3 / g, with a porosity of 82%. X-ray photoelectron spectroscopy analysis showed that the nitrogen doping content in this nitrogen-doped two-dimensional layered hierarchical porous carbon material was 3.5 wt%.

[0155] This embodiment also provides a supercapacitor, specifically a two-electrode symmetrical supercapacitor. The raw material includes the carbon-based energy storage electrode material (nitrogen-doped two-dimensional layered hierarchical porous carbon material) of this embodiment. The preparation method of the two-electrode symmetrical supercapacitor includes:

[0156] 80 wt% nitrogen-doped two-dimensional layered hierarchical porous carbon material, 10 wt% carbon black, and 10 wt% water-based binder (LA133 binder, also known as an aqueous dispersion of acrylonitrile copolymer) were dispersed in water and stirred for 5 h to prepare a water-based slurry. The resulting water-based slurry was then uniformly coated onto circular nickel foam to prepare a working electrode, which was dried in a vacuum oven. Glass fiber and 6M KOH solution were used as the separator and electrolyte, respectively, with working electrodes of equal mass on both sides of the separator and electrolyte, and the capacitor was assembled into a symmetrical supercapacitor.

[0157] After the supercapacitor was assembled, its electrochemical performance was evaluated. Figure 5 shows the cyclic voltammetry curve of the supercapacitor made of the carbon-based energy storage electrode material in this embodiment. As shown in Figure 5, the cyclic voltammetry curve exhibits a good rectangular shape at a scan rate of 100 mV / s, indicating that the material has ideal double-layer capacitance characteristics.

[0158] Figure 6 shows the rate performance curve of the supercapacitor made of the carbon-based energy storage electrode material of this embodiment. As shown in Figure 6, at a current density of 1 A / g, the specific capacitance of the supercapacitor reaches 287 F / g, and at a high current density of 30 A / g, the specific capacitance of the supercapacitor is 254 F / g, with a rate retention rate as high as 88.5%. After 50,000 cycles at a current density of 5 A / g, the capacity retention rate of the supercapacitor is as high as 99.8%, demonstrating excellent cycle stability.

[0159] Example 2

[0160] This embodiment provides a carbon-based energy storage electrode material and its preparation method. The preparation method of the carbon-based energy storage electrode material includes the following steps:

[0161] (1) Preparation steps of layered precursor: 4.5g aluminum borate and 8.0g aluminum hydroxide were mixed and added to 120mL of deionized water to form a solution. The pH of the solution was adjusted to 8.5 to form the first system. The reaction was carried out at 90℃ for 18h, cooled, washed and dried to obtain the layered first intermediate product.

[0162] 2.5g of the above-mentioned layered first intermediate product was dispersed in 75mL of ethanol-water mixed solution (ethanol to water volume ratio 3:1), and 0.5g of citric acid (the mass ratio of organic acid to the first intermediate product was 0.2:1) was added to form a second system. The reaction was carried out at 80℃ for 6h, and then cooled, filtered, washed and dried to obtain the second intermediate product.

[0163] (2) Mixing and compounding step: 2.5g of the second intermediate product obtained in step (1) and 0.5g of polyacrylonitrile are mixed at a mass ratio of 1:0.2. 1.0g of urea (the mass ratio of urea to the precursor is 0.4:1) is added as a pore control agent. The above components are thoroughly mixed in 50mL of tetrahydrofuran to form a third system. The third system is stirred and evaporated at 65℃ until it becomes viscous. It is then dried at 90℃ for 10h to obtain the composite precursor.

[0164] (3) Heat treatment steps: Place all the composite precursors obtained in step (2) in a tube furnace, and heat them to 380°C at a heating rate of 4°C / min under a mixed gas atmosphere of N2 and CO2 (volume ratio of 8:1, total flow rate of 250 mL / min) and hold for 2 h; then heat them to 800°C at a heating rate of 5°C / min and hold for 4 h. The gas pressure in the heat treatment pipe is 1 atmosphere; cool naturally to room temperature to obtain layered carbon / inorganic composite material.

[0165] (4) Acid washing step: Soak all the layered carbon / inorganic composite materials obtained in step (3) in 0.3 mol / L hydrochloric acid solution for 20 h at 60 °C; filter, wash with water until neutral, and dry at 105 °C for 12 h to obtain two-dimensional layered multi-level porous carbon material;

[0166] (5) Ammonia modification (nitrogen doping) step: Place all the two-dimensional layered multi-level porous carbon materials obtained in step (4) in a tube furnace, introduce NH3 gas with a flow rate of 100 mL / min, treat at 550℃ for 1.5 h, and cool naturally to room temperature to obtain carbon-based energy storage electrode material. The carbon-based energy storage electrode material is a nitrogen-doped two-dimensional layered multi-level porous carbon material.

[0167] The first intermediate product obtained in this embodiment can be a layered precursor (specifically, a layered hydroxide containing boron and aluminum elements), and the second intermediate product can be a layered precursor intercalated with organic acids.

[0168] Characterization was performed according to the method in Example 1, and the results are as follows: This nitrogen-doped two-dimensional layered hierarchical porous carbon material has a regular layered morphology, an average thickness of approximately 20 nm, and a lateral dimension of 3-8 μm. The specific surface area of ​​the material is 2810 m². 2 / g, pore size distribution is 0.7-35nm, micropores account for 36% of the total pore volume, mesopores account for 64% of the total pore volume, and the total pore volume is 2.15cm³. 3 / g, with a porosity of 85%. X-ray photoelectron spectroscopy analysis showed that the nitrogen doping content in this two-dimensional layered nitrogen-doped hierarchical porous carbon material was 3.2 wt%.

[0169] This embodiment also provides a supercapacitor, specifically a two-electrode symmetrical supercapacitor. The raw material includes the carbon-based energy storage electrode material (nitrogen-doped two-dimensional layered hierarchical porous carbon material) of this embodiment. The preparation method of the two-electrode symmetrical supercapacitor includes:

[0170] 80 wt% nitrogen-doped two-dimensional layered hierarchical porous carbon material, 10 wt% carbon black, and 10 wt% water-based binder (LA133 binder, also known as an aqueous dispersion of acrylonitrile copolymer) were dispersed in water and stirred for 5 h to prepare a slurry. The resulting water-based slurry was then uniformly coated onto circular nickel foam to prepare a working electrode, which was dried in a vacuum oven. Glass fiber and 1M H2SO4 solution were used as the separator and electrolyte, respectively, with working electrodes of equal mass on both sides of the separator and electrolyte, and the capacitor was assembled into a symmetrical supercapacitor.

[0171] After assembly, the supercapacitor underwent electrochemical performance evaluation using the same testing methods as in Example 1. At a current density of 1 A / g, the supercapacitor exhibited a specific capacitance of 295 F / g; at a high current density of 30 A / g, the specific capacitance was 259 F / g, with a rate retention rate as high as 87.8%. After 50,000 cycles at a current density of 5 A / g, the supercapacitor maintained a capacity retention rate of 99.7%, indicating excellent cycle stability.

[0172] Example 3

[0173] This embodiment provides a carbon-based energy storage electrode material and its preparation method. The preparation method of the carbon-based energy storage electrode material includes the following steps:

[0174] (1) Preparation steps of layered precursor: Mix 5.0g aluminum borate, 6.5g aluminum hydroxide and 1.5g magnesium hydroxide, add 110mL deionized water to form a solution, adjust the pH of the solution to 9.5 to form the first system, and hydrothermally react at 110℃ for 15 hours. Cool, wash and dry to obtain the layered first intermediate product.

[0175] 3.0 g of the above layered first intermediate product was dispersed in 90 mL of ethanol-water mixed solution (ethanol to water volume ratio 1:1), and 0.9 g of succinic acid (the mass ratio of organic acid to the first intermediate product was 0.3:1) was added to form a second system. The reaction was carried out at 75 °C for 10 h, and then cooled, filtered, washed and dried to obtain the second intermediate product.

[0176] (2) Mixing and compounding step: 3.0g of the second intermediate product obtained in step (1) and 1.8g of phenolic resin are mixed at a mass ratio of 1:0.6. 1.2g of urea (mass ratio of urea to precursor is 0.4:1) is added as a pore control agent. The above components are thoroughly mixed in a 60mL mixed solution of acetone and DMF (volume ratio of acetone to DMF is 1:1) to form a third system. The third system is stirred and evaporated at 75℃ until it becomes viscous, and then dried at 95℃ for 9h to obtain the composite precursor.

[0177] (3) Heat treatment steps: Place all the composite precursors obtained in step (2) in a tube furnace, and heat them to 420°C at a heating rate of 6°C / min under a mixed gas atmosphere of N2 and CO2 (the volume ratio of N2 and CO2 is 6:1 and the total flow rate is 180 mL / min). Hold for 2.5 h; then heat them to 880°C at a heating rate of 7°C / min. Hold for 3.5 h. The gas pressure in the heat treatment pipe is 1 atmosphere. Cool naturally to room temperature to obtain layered carbon / inorganic composite material.

[0178] (4) Acid washing step: Soak all the layered carbon / inorganic composite materials obtained in step (3) in a mixed solution of 0.4 mol / L sulfuric acid and 0.2 mol / L nitric acid for 14 h at a temperature of 70 °C; filter, wash with water until neutral, and dry at 115 °C for 9 h to obtain two-dimensional layered multi-level porous carbon material;

[0179] (5) Ammonia modification (nitrogen doping) step: Place all the two-dimensional layered multi-level porous carbon materials obtained in step (4) into a tube furnace, introduce NH3 gas with a flow rate of 200 mL / min, treat at 650℃ for 0.8 h, and cool naturally to room temperature to obtain carbon-based energy storage electrode material. The carbon-based energy storage electrode material is a nitrogen-doped two-dimensional layered multi-level porous carbon material.

[0180] The first intermediate product obtained in this embodiment can be a layered precursor (specifically, a layered hydroxide containing boron, aluminum, and magnesium elements), and the second intermediate product can be a layered precursor intercalated with organic acid.

[0181] This nitrogen-doped two-dimensional layered hierarchical porous carbon material exhibits a regular layered morphology, with an average thickness of approximately 45 nm and lateral dimensions of 8–15 μm. The material has a specific surface area of ​​3100 m². 2 / g, pore size distribution is 1.0-40nm, micropore volume accounts for 28% of the total pore volume, mesopore volume accounts for 72% of the total pore volume, and the total pore volume is 2.62cm³. 3 / g, with a porosity of 87%. X-ray photoelectron spectroscopy analysis showed that the nitrogen doping content in this nitrogen-doped two-dimensional layered hierarchical porous carbon material was 4.3 wt%.

[0182] This embodiment also provides a supercapacitor, specifically a two-electrode symmetrical supercapacitor. The raw material includes the carbon-based energy storage electrode material (nitrogen-doped two-dimensional layered hierarchical porous carbon material) of this embodiment. The preparation method of the two-electrode symmetrical supercapacitor includes:

[0183] 80 wt% nitrogen-doped two-dimensional layered hierarchical porous carbon material, 10 wt% carbon black, and 10 wt% water-based binder (LA133 binder, also known as an aqueous dispersion of acrylonitrile copolymer) were dispersed in water and stirred for 5 h to prepare a slurry. The resulting water-based slurry was then uniformly coated onto circular nickel foam to prepare a working electrode, which was then dried in a vacuum oven. Glass fiber and 6M KOH solution were used as the separator and electrolyte, respectively, with working electrodes of equal mass on both sides of the separator and electrolyte, to assemble a symmetrical supercapacitor.

[0184] After assembly, the supercapacitor underwent electrochemical performance evaluation using the same testing methods as in Example 1. At a current density of 1 A / g, the supercapacitor achieved a specific capacitance of 320 F / g; at a high current density of 30 A / g, the specific capacitance was 285 F / g, with a rate retention rate as high as 89.1%. After 50,000 cycles at a current density of 5 A / g, the supercapacitor maintained a capacity retention rate of 99.8%, indicating excellent cycle stability.

[0185] Example 4

[0186] This embodiment provides a carbon-based energy storage electrode material and its preparation method. The preparation method of the carbon-based energy storage electrode material includes the following steps:

[0187] (1) Preparation steps of layered precursor: Mix 5.5g aluminum borate and 8.5g aluminum hydroxide, add 105mL of deionized water to form a solution, adjust the pH of the solution to 8.8 to form the first system, and hydrothermally react at 105℃ for 16h. Cool, wash and dry to obtain the layered first intermediate product.

[0188] 2.8 g of the above layered first intermediate was dispersed in 80 mL of ethanol-water mixed solution (volume ratio of ethanol to water 2.5:1), and 0.7 g of malic acid (mass ratio of organic acid to first intermediate was 0.25:1) was added to form a second system. The reaction was carried out at 65 °C for 12 h, and then cooled, filtered, washed and dried to obtain the second intermediate.

[0189] (2) Mixing and compounding step: 2.8g of the second intermediate product obtained in step (1) and 2.1g of furan resin are mixed at a mass ratio of 1:0.75. 0.7g of urea (the mass ratio of urea to precursor is 0.25:1) is added as a pore control agent. The above components are thoroughly mixed in 55mL of DMF to form a third system. The third system is stirred and evaporated at 80℃ until it becomes viscous. It is then dried at 105℃ for 6h to obtain the composite precursor.

[0190] (3) Heat treatment steps: Place all the composite precursors obtained in step (2) in a tube furnace, and heat them to 450°C at a heating rate of 5.5°C / min under a mixed gas atmosphere of N2 and CO2 (the volume ratio of N2 and CO2 is 9:1 and the total flow rate is 300 mL / min), and hold for 2 h; then heat them to 900°C at a heating rate of 6.5°C / min, and hold for 2.5 h. The gas pressure in the heat treatment pipe is 1 atmosphere; cool naturally to room temperature to obtain layered carbon / inorganic composite material.

[0191] (4) Acid washing step: Soak all the layered carbon / inorganic composite materials obtained in step (3) in 0.6 mol / L sulfuric acid solution for 18 h at 75 °C; filter, wash with water until neutral, and dry at 120 °C for 8 h to obtain two-dimensional layered multi-level porous carbon material;

[0192] (5) Ammonia modification (nitrogen doping) step: Place all the two-dimensional layered multi-level porous carbon materials obtained in step (4) into a tube furnace, introduce NH3 gas with a flow rate of 250 mL / min, treat at 580℃ for 1.2 h, and cool naturally to room temperature to obtain nitrogen-doped two-dimensional layered multi-level porous carbon materials.

[0193] The first intermediate product obtained in this embodiment can be a layered precursor (specifically, a layered hydroxide containing boron and aluminum elements), and the second intermediate product can be a layered precursor intercalated with organic acid.

[0194] This nitrogen-doped two-dimensional layered hierarchical porous carbon material exhibits a regular layered morphology, with an average thickness of approximately 35 nm and lateral dimensions of 6–12 μm. The material has a specific surface area of ​​3300 m². 2 / g, pore size distribution is 0.8-45nm, micropores account for 31% of the total pore volume, mesopores account for 69% of the total pore volume, and the total pore volume is 2.86cm³. 3 / g, with a porosity of 89%. X-ray photoelectron spectroscopy analysis showed that the nitrogen doping content in this two-dimensional layered nitrogen-doped hierarchical porous carbon material was 4.8 wt%.

[0195] This embodiment also provides a supercapacitor, specifically a two-electrode symmetrical supercapacitor. The raw material includes the carbon-based energy storage electrode material (nitrogen-doped two-dimensional layered hierarchical porous carbon material) of this embodiment. The preparation method of the two-electrode symmetrical supercapacitor includes:

[0196] 80 wt% nitrogen-doped two-dimensional layered hierarchical porous carbon material, 10 wt% carbon black, and 10 wt% water-based binder (LA133 binder, also known as an aqueous dispersion of acrylonitrile copolymer) were dispersed in water and stirred for 5 h to prepare a slurry. The resulting water-based slurry was then uniformly coated onto circular nickel foam to prepare a working electrode, which was then dried in a vacuum oven. Glass fiber and 1M H2SO4 solution were used as the separator and electrolyte, respectively, with working electrodes of equal mass on both sides of the separator and electrolyte, to assemble a symmetrical supercapacitor.

[0197] Electrochemical performance was evaluated after the supercapacitor was assembled. At a current density of 1 A / g, the supercapacitor exhibited a specific capacitance of 342 F / g; at a high current density of 30 A / g, the specific capacitance was 295 F / g, with a rate retention rate as high as 86.2%. After 50,000 cycles at a current density of 5 A / g, the supercapacitor retained 99.7% of its capacity, indicating excellent cycle stability.

[0198] Comparative Example 1

[0199] This comparative example provides a nitrogen-doped carbon material, which is prepared by referring to the preparation method of Example 1. The difference between the preparation method of Example 1 and Example 1 is that the mixed gas atmosphere of N2 and CO2 in the heat treatment step (3) of this comparative example is changed to a pure N2 gas atmosphere, while the remaining steps and conditions are the same as those of Example 1.

[0200] The nitrogen-doped carbon material prepared in Comparative Example 1 has a specific surface area of ​​85 m². 2 / g, the pore size distribution is uneven, the proportion of mesopore volume in the total pore volume is significantly reduced to only 40%, while the proportion of micropore volume in the total pore volume increases to 60%.

[0201] The nitrogen-doped carbon material obtained in this comparative example was used as the electrode material of the supercapacitor. It was assembled into a two-electrode symmetrical supercapacitor according to the method of Example 1 and electrochemical tests were performed. The specific capacitance of the supercapacitor at a current density of 1 A / g was only 30 F / g, and the specific capacitance dropped to 5 F / g at a current density of 30 A / g, with a rate retention rate of only 16.7%. After 50,000 cycles at a current density of 5 A / g, the capacity retention rate was only 14.5%.

[0202] The nitrogen-doped carbon material prepared in Comparative Example 1 exhibits significantly lower performance than the nitrogen-doped two-dimensional layered hierarchical porous carbon materials in Examples 1 to 4. This is primarily because the lack of CO2 gas participation in the heat treatment process prevents the effective formation of a well-developed mesoporous structure, resulting in uneven pore size distribution, predominantly micropores, which is detrimental to the rapid transport of electrolyte ions. This demonstrates that by controlling the type of heat treatment atmosphere in this invention, mesopore formation can be promoted, facilitating the preparation of high-performance layered hierarchical porous carbon materials as carbon-based energy storage electrode materials.

[0203] Comparative Example 2

[0204] This comparative example provides a nitrogen-doped carbon material, the preparation method of which is the same as that of Example 2. The difference between the preparation method of Example 2 and that of Example 2 is that the preparation step (1) of the layered precursor is changed to not adding organic acid for intercalation treatment. That is, the product of aluminum borate and aluminum hydroxide (the first intermediate product) is directly mixed with polyurethane resin and urea for subsequent processes. The remaining steps and conditions are the same as those of Example 2.

[0205] Although the nitrogen-doped carbon material prepared in Comparative Example 2 maintained its layered morphology, its thickness increased to over 100 nm, with smaller interlayer spacing and severe layer stacking. The specific surface area of ​​the material decreased to 152 m². 2 The pore size distribution is predominantly micropores (micropore volume accounts for 68% of the total pore volume), while mesopore volume accounts for only 32%. As a supercapacitor electrode material, it was assembled into a two-electrode symmetrical supercapacitor according to the method in Example 1, and electrochemical tests were conducted. The specific capacitance of the supercapacitor at a current density of 1 A / g was only 42 F / g, and at a current density of 30 A / g, the specific capacitance dropped to 8 F / g, with a rate retention of only 19.0%; after 50,000 cycles at a current density of 5 A / g, the capacity retention was only 10.2%.

[0206] The nitrogen-doped carbon material prepared in Comparative Example 2 exhibits significantly lower performance than the nitrogen-doped two-dimensional layered hierarchical porous carbon materials in Examples 1 to 4. This is mainly because the lack of organic acid intercalation treatment results in a smaller interlayer spacing of the layered precursor, preventing the carbon precursor from effectively penetrating into the interlayer space. Furthermore, the pore structure formed during heat treatment is primarily concentrated in the micropore region, with insufficient interlayer connectivity, leading to a significant decrease in conductivity and electrochemical performance. This demonstrates that the organic acid intercalation treatment of layered hydroxides in this invention promotes mesopore formation, facilitating the preparation of high-performance two-dimensional layered hierarchical porous carbon materials for carbon-based energy storage electrode materials.

[0207] The above results demonstrate that the carbon-based energy storage electrode material provided by this invention possesses a regular two-dimensional layered morphology and a well-developed hierarchical porous structure (including micropores and mesopores), with high specific surface area, pore volume, and abundant interlayer porosity. When applied as an electrode material in energy storage devices such as supercapacitors, this carbon-based energy storage electrode material exhibits excellent electron / ion transport and electrochemical performance, as well as high capacity, rate performance, and cycle performance.

[0208] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a carbon-based energy storage electrode material, characterized in that, The preparation method includes: S1, mixing aluminum borate and raw material hydroxide in water to form a first system, and performing a first hydrothermal reaction to obtain a first intermediate product; S2, mixing the first intermediate product with an organic acid in a mixed solvent to form a second system, and performing a second hydrothermal reaction to obtain a second intermediate product; S3, mixing the second intermediate product with a carbon source and a pore regulator in an organic solvent to form a third system, removing the solvent to obtain a composite precursor; S4, heat-treating the composite precursor in a mixed atmosphere of N2 and CO2 to obtain a carbon / inorganic composite material; S5, acid-washing the carbon / inorganic composite material, then filtering, washing, and drying to obtain the carbon-based energy storage electrode material.

2. The preparation method according to claim 1, characterized in that, In S1, the molar ratio of aluminum borate to raw material hydroxide is 1:1-5; the raw material hydroxide includes at least aluminum hydroxide; and / or, the temperature of the first hydrothermal reaction is 80-120°C, and the time of the first hydrothermal reaction is 6-24h; and / or, the pH value of the first system is 8.0-10.

0.

3. The preparation method according to claim 2, characterized in that, In S1, the raw material hydroxide also includes one or more of magnesium hydroxide, calcium hydroxide, and zinc hydroxide.

4. The preparation method according to claim 1, characterized in that, In S2, the mass ratio of the organic acid to the first intermediate product is 0.1-0.5:1; and / or, the organic acid includes one or more of succinic acid, citric acid, malic acid, and tartaric acid; and / or, the temperature of the second hydrothermal reaction is 60-90°C, and the time of the second hydrothermal reaction is 4-12 hours.

5. The preparation method according to claim 1, characterized in that, In S3, the mass ratio of the second intermediate product to the carbon source is 1:0.2-0.8; the mass ratio of the pore regulator to the second intermediate product is 0.1-0.6:1; and / or, the carbon source includes one or more of polyurethane resin, polyacrylonitrile, phenolic resin, furan resin, asphalt, petroleum coke, and heavy oil; and / or, the pore regulator includes one or more of urea, polymethyl methacrylate, chlorinated polyethylene fiber, and block copolymer.

6. The preparation method according to claim 1, characterized in that, In S4, the volume ratio of N2 to CO2 in the mixed atmosphere of N2 and CO2 is 4:1-9:

1.

7. The preparation method according to claim 1, characterized in that, In S4, the heat treatment includes a first heat treatment and a second heat treatment performed sequentially; the heating rate of the first heat treatment is 3-7℃ / min, the temperature of the first heat treatment is 350-450℃, and the holding time of the first heat treatment is 2-4h; the heating rate of the second heat treatment is 4-8℃ / min, the temperature of the second heat treatment is 750-900℃, and the holding time of the second heat treatment is 2-5h.

8. The preparation method according to claim 1, characterized in that, S5 of the preparation method further includes nitrogen doping of the dried product; the nitrogen doping process includes: heat-treating the dried product in a nitrogen-containing gas to complete the nitrogen doping; the heat treatment temperature is 500-700℃, and the holding time is 0.5-2h; the flow rate of the nitrogen-containing gas is 50-1000 mL / min; the nitrogen-containing gas includes one or more of ammonia, urea vapor, pyridine vapor, and methylamine gas.

9. A carbon-based energy storage electrode material, characterized in that, The carbon-based energy storage electrode material is obtained by the preparation method of the carbon-based energy storage electrode material according to any one of claims 1-8.

10. The carbon-based energy storage electrode material according to claim 9, characterized in that, The carbon-based energy storage electrode material comprises a two-dimensional layered hierarchical porous carbon material and / or a nitrogen-doped two-dimensional layered hierarchical porous carbon material; the carbon-based energy storage electrode material has a two-dimensional sheet morphology, an average thickness of 5-100 nm, a lateral dimension of 0.05-10 μm, and / or, the carbon-based energy storage electrode material has micropores and mesopores; the pore volume of the micropores accounts for 20%-50% of the total pore volume, and the pore volume of the mesopores accounts for 50-80% of the total pore volume; and / or, the specific surface area of ​​the carbon-based energy storage electrode material is 1500-3500 m². 2 / g; and / or, the porosity of the carbon-based energy storage electrode material is 75%-90%; and / or, the total pore volume of the carbon-based energy storage electrode material is 1.5-4.0 cm³. 3 / g; and / or, the micropore and mesopore pore size distribution of the carbon-based energy storage electrode material is 0.5-50nm.

11. A supercapacitor, characterized in that, The electrode material of the supercapacitor includes the carbon-based energy storage electrode material as described in claim 9 or 10.

12. The application of the carbon-based energy storage electrode material according to claim 9 or 10 in fuel cells, lithium-ion batteries, lithium-ion capacitors, sodium-ion batteries, lithium-sulfur batteries, gas adsorption and separation materials, water treatment adsorption materials, or drug carriers.

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