Preparation method and application of enzymatic hydrolysis lignin-based porous carbon material

Abstract

The invention belongs to the technical field of activated carbon materials, and particularly relates to a preparation method and application of an enzymolysis lignin-based porous carbon material. The preparation method of the enzymatic hydrolysis lignin-based porous carbon material comprises the following steps: 1) preparing a tannic acid solution and a chloroacetic acid solution, adding the chloroacetic acid solution into the tannic acid solution, carrying out a heating reaction, and regulating the pH during the reaction to obtain carboxylated tannic acid; (2) adding the enzymatic hydrolysis lignin, carboxylated tannic acid and phenol into alkali liquor, uniformly mixing, adjusting the pH value, adding formaldehyde, and heating for reaction to obtain modified enzymatic hydrolysis lignin; and 3) carbonizing the modified enzymatic hydrolysis lignin, crushing the obtained carbonized material, doping an alkali activator, activating, and crushing again to obtain the enzymatic hydrolysis lignin-based porous carbon material. The carboxyl of the carboxylated tannic acid is decomposed in the carbonization / activation process to release CO2 and other small molecule gases, and the carboxylated tannic acid and the alkali activating agent realize synergistic controllable pore-forming / pore-expanding; the carboxylated tannic acid improves the final yield of the activated carbon, and a cross-linked skeleton formed by the carboxylated tannic acid can buffer the etching strength of the alkali activator.

Description

Technical Field

[0001] This invention belongs to the field of activated carbon materials technology, specifically relating to a method for preparing enzymatically hydrolyzed lignin-based porous carbon materials and their applications. Background Technology

[0002] Supercapacitors (also known as electrochemical capacitors) possess significant advantages such as high power density, fast charge / discharge speed, long cycle life, wide operating temperature range, and good safety, demonstrating enormous application potential in fields such as new energy vehicles, smart grids, portable electronic devices, and national defense. Electrode materials are the core components determining the energy storage performance of supercapacitors. Ideal supercapacitor electrode materials require high specific surface area to provide sufficient charge storage sites, a reasonable hierarchical pore structure to promote electrolyte ion transport, a good conductive network to reduce charge transfer resistance, and excellent surface chemical tunability to enhance interfacial wettability. Carbon-based materials, due to their high specific surface area, excellent pore structure controllability, good chemical stability, and conductivity, can achieve charge storage by forming an electric double layer at the electrode-electrolyte interface, making them the preferred electrode material for supercapacitors.

[0003] Carbon-based electrode materials mainly include carbon black, activated carbon, carbon fibers, carbon nanotubes, and graphene. Among them, activated carbon is one of the most widely used carbon-based electrode materials in the field of supercapacitors due to its relatively simple preparation process and easily controllable specific surface area. Enzymatically hydrolyzed lignin is derived from the residue remaining after the extraction of sugars from biomass (such as corn stalks and wheat stalks) by cellulase hydrolysis. It has a carbon content of over 60% and a unique three-dimensional cross-linked network structure, making it an ideal precursor for activated carbon. Using enzymatically hydrolyzed lignin to prepare activated carbon not only enables the high-value utilization of industrial waste but also significantly reduces the preparation cost of carbon materials. For example, patent CN107304048B discloses a method for preparing porous carbon of polyacrylic acid grafted lignin. This patent uses polyacrylic acid grafted lignin as the material, controls the porosity of activated carbon by controlling the surface functional groups of the precursor and the steric hindrance of lignin in the polymer gel, and carbonizes the polyacrylic acid grafted lignin composite material to prepare a low-cost, high specific surface area, and internally continuous porous carbon electrode material. This technology grafts a large amount of polyacrylic acid onto enzymatically hydrolyzed lignin molecular chains to achieve high specific surface area and high mesoporous ratio. By utilizing the pore-forming effect of acidic small molecules (such as acetic acid and propionic acid) generated by the high-temperature pyrolysis of the grafted chains and the residual characteristics of functional groups, porous carbon electrode materials with high specific surface area and excellent electrochemical performance are prepared. Although the large amount of acidic products generated by the pyrolysis of polyacrylic acid helps to create pores and increase specific surface area, most of them are lost in gaseous form after pyrolysis, resulting in high macroporosity of activated carbon, but low specific surface area, mesoporous ratio, and yield, and poor electrochemical performance.

[0004] Patent CN109354018B discloses a method for preparing high specific surface area activated carbon microspheres, belonging to the field of special carbon material preparation technology. This patent uses lignin as a carbon precursor, mixing and fully dissolving it with an aqueous solution of activating agents such as sodium hydroxide. A small amount of graphene is also dispersed in this aqueous solution. Raw material microspheres are prepared by spray drying, followed by stabilization pretreatment in air. Then, under an inert atmosphere, they undergo high-temperature carbonization and activation. Finally, a simple acid washing and water washing process yields activated carbon microspheres with high electrical conductivity and high specific surface area. This technology uses enzymatically hydrolyzed lignin as raw material, supplemented with an appropriate amount of graphene to prepare activated carbon microspheres. This not only achieves high-value utilization and pore structure control of enzymatically hydrolyzed lignin but also improves the carbonization yield of enzymatically hydrolyzed lignin. However, since graphene does not form covalent bonds with the enzymatically hydrolyzed lignin-based carbon skeleton, phase separation is prone to occur during high-temperature carbonization / activation. Although the addition of graphene improves the conductivity of activated carbon microspheres to some extent, when the supercapacitor is charged and discharged at high rates, the electron transport demand increases exponentially. The broken conductive network at the phase separation interface leads to a sharp increase in charge transfer resistance and equivalent series resistance, which manifests as a significant decrease in specific capacitance.

[0005] Therefore, it is necessary to develop a method for preparing lignin-based activated carbon that has high utilization rate of enzymatic hydrolysis of lignin, high yield of activated carbon, and excellent electrochemical performance. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for preparing enzymatically hydrolyzed lignin-based porous carbon materials and their applications. This invention uses chloroacetic acid to carboxylate-modify tannic acid, resulting in carboxylated tannic acid with a large number of carboxyl groups and abundant phenolic hydroxyl groups. During carbonization / activation, the carboxyl groups decompose and release small molecule gases such as CO2 to create / expand pores, achieving synergistic and controllable pore creation / expansion with the alkali activator. Simultaneously, its active phenolic hydroxyl groups undergo co-condensation reactions with enzymatically hydrolyzed lignin, phenol, and formaldehyde, covalently linking themselves to the modified enzymatically hydrolyzed lignin molecules to form a three-dimensional cross-linked precursor. Carboxylated tannic acid not only serves as a high-residual-carbon component, improving the yield of the final activated carbon, but the stable cross-linked framework it participates in also buffers the etching intensity of the subsequent alkali activator, preventing the collapse of the activated carbon's pore structure. The final enzymatically hydrolyzed lignin has high utilization, resulting in a high-yield activated carbon material with high specific surface area and excellent electrochemical performance.

[0007] To achieve the above objectives, the following technical solution is adopted:

[0008] A method for preparing lignin-based porous carbon materials by enzymatic hydrolysis includes the following steps:

[0009] 1) Tannic acid solution and chloroacetic acid solution are mixed and heated to react, yielding carboxylated tannic acid;

[0010] 2) Add enzymatically hydrolyzed lignin, carboxylated tannic acid, and phenol to an alkaline solution and mix well. Adjust the pH to 9-11, add formaldehyde, and heat to react to obtain modified enzymatically hydrolyzed lignin.

[0011] 3) The modified enzymatic hydrolyzed lignin is carbonized, the resulting carbonized material is crushed, an alkali activator is added, and it is activated at high temperature under an inert atmosphere. It is then crushed again to obtain enzymatic hydrolyzed lignin-based porous carbon material.

[0012] In step 1), the molar ratio of tannic acid to chloroacetic acid is 1:6-10, preferably 1:6-8.

[0013] In step 1), the tannic acid solution is prepared by dissolving tannic acid in water at 0-10℃ and adjusting the pH to 7.5-9 with an alkaline solution. The chloroacetic acid solution is prepared by dissolving chloroacetic acid in water at 0-10℃ and adjusting the pH to 7.5-9 with an alkaline solution. The alkaline solution is selected from one or more combinations of sodium hydroxide solution, sodium carbonate solution, and sodium bicarbonate solution; the concentration of the alkaline solution is 5-20 wt%.

[0014] In step 1), the chloroacetic acid solution is added dropwise to the tannic acid solution, completing the addition over 1-2 hours. The heating reaction is carried out at 50-60°C for 3-5 hours. The alkaline solution is prepared in the same manner.

[0015] Step 1) further includes acidification, filtration, precipitation of the filtrate with acetone, filtration, washing, and drying of the precipitate after the reaction is completed. Acidification involves adjusting the pH of the system to 3-4 with 5-15 wt% hydrochloric acid. Precipitation of the filtrate with acetone involves adding 3-5 times the volume of acetone to the filtrate. Washing involves washing with water 1-3 times. Drying the precipitate involves drying at 40-60℃ and -0.08 to -0.1 MPa for 8-12 hours.

[0016] In step 2), the mass ratio of enzymatically hydrolyzed lignin, carboxylated tannic acid, phenol, and formaldehyde is 4-5:1.5-2.5:0.5-1:2.8-3.5, preferably 5:1.5-2:0.5-1:2.8-3.5.

[0017] The formaldehyde was added in the form of a 20-37 wt% formaldehyde aqueous solution.

[0018] In step 2), the enzymatically hydrolyzed lignin is a natural polymer material extracted from the residue of microbial enzymatic hydrolysis of straw to produce ethanol, functional polysaccharides, or biogas using an organic solvent. The microbial enzymatic hydrolysis of straw is carried out under mild conditions, and the hydrolyzed lignin retains a large number of active groups, such as phenolic hydroxyl groups. The enzymatically hydrolyzed lignin has a weight-average molecular weight of 1000-3000 and a phenolic hydroxyl content of 3-8 wt%. The alkaline solution is selected from one or a combination of sodium hydroxide solution and potassium hydroxide solution. The concentration of the alkaline solution is 5-10 wt%.

[0019] In step 2), adjusting the pH to 9-11 involves using 5-10 wt% NaOH solution or 5-10 wt% hydrochloric acid to adjust it to 9-11. The heating reaction involves heating to 70-90℃ and reacting for 2-5 hours.

[0020] Step 2) further includes post-reaction processing operations such as filtration, crushing, washing, and drying after the reaction is completed. Crushing involves crushing the particles to an average particle size of 1-5 mm. Washing involves adding the crushed particles to water at a solid-liquid mass ratio of 1:5-10, repeating the washing process 2-5 times. Drying involves drying at 60-90℃ to a constant weight.

[0021] In step 3), the carbonization conditions are: 400-600℃ for 1-2 hours under an inert atmosphere. The crushing is performed to a particle size of 0.1-0.5 mm. The activation conditions are: 700-900℃ for 1-2 hours under an inert atmosphere. The inert atmosphere is nitrogen and / or argon. The re-crushing is performed to a particle size of 1-10 μm.

[0022] In step 3), the mass ratio of the alkali activator to the carbonized material is 3-5:1. The alkali activator is selected from one or a combination of two of potassium hydroxide and sodium hydroxide.

[0023] This invention also provides the application of the enzymatically hydrolyzed lignin-based porous carbon material prepared by the above-described method, wherein the enzymatically hydrolyzed lignin-based porous carbon material is used to prepare electrode materials for supercapacitors.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] This invention utilizes chloroacetic acid to carboxylate tannic acid, resulting in carboxylated tannic acid with abundant carboxyl groups and retained phenolic hydroxyl groups. During carbonization / activation, the carboxyl groups decompose and release small-molecule gases such as CO2 to create / expand pores, achieving synergistic and controllable pore creation / expansion with the alkali activator. Simultaneously, the active phenolic hydroxyl groups covalently link themselves to the modified enzymatically hydrolyzed lignin molecules through co-condensation reactions with enzymatically hydrolyzed lignin, phenol, and formaldehyde, forming a three-dimensional cross-linked precursor. Carboxylated tannic acid not only enhances the yield of the final activated carbon as a high-residual-carbon component, but the stable cross-linked framework it participates in also buffers the etching intensity of subsequent alkali activators, preventing the collapse of the activated carbon's pore structure. The final enzymatically hydrolyzed lignin has high utilization, resulting in a high-yield activated carbon material with high specific surface area and excellent electrochemical performance. Attached Figure Description

[0026] Figure 1 SEM image of the enzymatically hydrolyzed lignin-based porous carbon material prepared in Example 1. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments, but is not limited to the contents of the specification. Unless otherwise specified, all "parts" mentioned in the embodiments of the present invention are parts by weight. All reagents used are commercially available in the art.

[0028] Enzymatically hydrolyzed lignin 1# has a weight-average molecular weight of 1260 and a phenolic hydroxyl content of 7.5wt%; enzymatically hydrolyzed lignin 2# has a weight-average molecular weight of 2880 and a phenolic hydroxyl content of 3.8wt%. Both enzymatically hydrolyzed lignins were extracted from the residue of microbial enzymatic hydrolysis of corn stalks to produce ethanol using dioxane, and were obtained from Shanxi Biomass New Materials Industry Research Institute Co., Ltd.

[0029] Example 1

[0030] 1) Dissolve 1 mol of tannic acid in 5 L of water at 0 °C, and adjust the pH to 8 with a 10 wt% sodium hydroxide solution to obtain a tannic acid solution; dissolve 6 mol of chloroacetic acid in 5 L of water at 0 °C, and adjust the pH to 8 with a 10 wt% sodium hydroxide solution to obtain a chloroacetic acid solution; add the chloroacetic acid solution dropwise to the tannic acid solution, and the addition is completed in 2 h. The temperature is raised to 50 °C and reacted for 5 h. After the reaction is completed, the pH of the system is adjusted to 3 with 10 wt% hydrochloric acid, filtered, and precipitated by adding 5 times the volume of acetone to the filtrate. The precipitate is filtered, washed 3 times with water, and dried at 60 °C and -0.08 MPa for 12 h to obtain carboxylated tannic acid;

[0031] 2) Add 5 kg of enzymatically hydrolyzed lignin 1#, 2 kg of carboxylated tannic acid, and 0.5 kg of phenol to 25 L of 10 wt% sodium hydroxide solution and mix well. Adjust the pH to 10 with 5 wt% hydrochloric acid. Add a 37 wt% formaldehyde aqueous solution containing 3.5 kg of formaldehyde and heat to 85 ℃ for 5 h. After the reaction is complete, filter, dry the solid phase, and crush it into particles with an average particle size of 4.8 mm. Add the crushed particles to water at a solid-liquid mass ratio of 1:5 and wash twice. Finally, dry at 60 ℃ to constant weight to obtain modified enzymatically hydrolyzed lignin.

[0032] 3) The modified enzymatic hydrolyzed lignin was carbonized at 400℃ for 2 hours under a nitrogen atmosphere. The resulting carbonized material was crushed to an average particle size of 0.1 mm. Sodium hydroxide was added at a mass ratio of alkali activator to carbonized material of 5:1. The material was activated at 900℃ for 1 hour under a nitrogen atmosphere and then crushed again to an average particle size of 4.8 μm to obtain enzymatic hydrolyzed lignin-based porous carbon material.

[0033] Example 2

[0034] The rest is the same as in Example 1, except that in step 1), the amount of chloroacetic acid used is 8 mol.

[0035] Example 3

[0036] The rest is the same as in Example 1, except that in step 1), the amount of chloroacetic acid used is 10 mol.

[0037] Example 4

[0038] The rest is the same as in Example 1, except that in step 2), the amount of carboxylated tannic acid used is 1.5 kg.

[0039] Example 5

[0040] The rest is the same as in Example 1, except that in step 2), the amount of carboxylated tannic acid used is 2.5 kg.

[0041] Example 6

[0042] The rest is the same as in Example 1, except that in step 2), the amount of enzymatic hydrolysis of lignin is 4 kg.

[0043] Example 7

[0044] The rest is the same as in Example 1, except that in step 3), sodium hydroxide is added at a mass ratio of 3:1 between the alkali activator and the carbonized material.

[0045] Example 8

[0046] 1) Dissolve 1 mol of tannic acid in 5 L of water at 0℃, and adjust the pH to 7.5 with a 10 wt% sodium hydroxide solution to obtain a tannic acid solution; dissolve 6 mol of chloroacetic acid in 5 L of water at 0℃, and adjust the pH to 8 with a 10 wt% sodium hydroxide solution to obtain a chloroacetic acid solution; add the chloroacetic acid solution dropwise to the tannic acid solution, and the addition is completed in 2 h. The temperature is raised to 50℃ and reacted for 5 h. After the reaction is completed, the pH of the system is adjusted to 3 with 10 wt% hydrochloric acid, filtered, and precipitated by adding 5 times the volume of acetone to the filtrate. After filtration, the precipitate is washed 3 times with water, and dried at 60℃ and -0.08 MPa for 12 h to obtain carboxylated tannic acid;

[0047] 2) Add 5 kg of enzymatically hydrolyzed lignin 2#, 1.5 kg of carboxylated tannic acid, and 1 kg of phenol to 25 L of 10 wt% sodium hydroxide solution and mix well. Adjust the pH to 9 with 5 wt% hydrochloric acid. Add a 37 wt% formaldehyde aqueous solution containing 2.8 kg of formaldehyde and heat to 85 °C for 5 h. After the reaction is complete, filter, dry the solid phase, and crush it into particles with an average particle size of 4.8 mm. Add the crushed particles to water at a solid-liquid mass ratio of 1:5 and wash twice. Finally, dry at 60 °C to constant weight to obtain modified enzymatically hydrolyzed lignin.

[0048] 3) The modified enzymatic hydrolyzed lignin was carbonized at 400℃ for 2 hours under a nitrogen atmosphere. The resulting carbonized material was crushed to an average particle size of 0.1 mm. Sodium hydroxide was added at a mass ratio of alkali activator to carbonized material of 5:1. The material was activated at 900℃ for 1 hour under a nitrogen atmosphere and then crushed again to an average particle size of 4.8 μm to obtain enzymatic hydrolyzed lignin-based porous carbon material.

[0049] Comparative Example 1

[0050] 1) Add 5 kg of enzymatically hydrolyzed lignin and 2.5 kg of phenol to 25 L of 10 wt% sodium hydroxide solution and mix well. Adjust the pH to 10 with 5 wt% hydrochloric acid. Add a 37 wt% formaldehyde aqueous solution containing 3.5 kg of formaldehyde and heat to 85 °C for 5 h. After the reaction is complete, filter and crush to particles with an average particle size of 4.8 mm. Add the crushed particles to water at a solid-liquid mass ratio of 1:5 and wash twice. Finally, dry at 60 °C to constant weight to obtain modified enzymatically hydrolyzed lignin.

[0051] 2) The modified enzymatic hydrolyzed lignin was carbonized at 400℃ for 2 hours under a nitrogen atmosphere. The resulting carbonized material was crushed to an average particle size of 0.1 mm. Sodium hydroxide was added at a mass ratio of alkali activator to carbonized material of 5:1. The material was activated at 900℃ for 1 hour under a nitrogen atmosphere and then crushed again to an average particle size of 4.8 μm to obtain enzymatic hydrolyzed lignin-based porous carbon material.

[0052] Comparative Example 2

[0053] Activated carbon was prepared according to the method in Example 3 of patent CN107304048B, and the activated carbon yield was the percentage of porous carbon material to polyacrylic acid grafted lignin.

[0054] Application examples

[0055] Electrode sheet preparation: The mass percentages of enzymatically hydrolyzed lignin-based porous carbon material, PVDF binder, and acetylene black conductive agent are 80:12:8. First, the binder is dissolved in N-methylpyrrolidone to prepare a 0.02 g / ml solution. Then, the enzymatically hydrolyzed lignin-based porous carbon material and conductive agent are added to the binder solution and stirred until a paste is formed. This paste is then coated onto a nickel foam current collector and dried in a vacuum drying oven at 100°C for 12 hours. Finally, it is pressed into tablets at 20 MPa using a tablet press and cut into electrode sheets to obtain the electrode sheets.

[0056] Assemble the supercapacitor: Place the electrode sheet / porous polypropylene separator / electrode sheet into the button cell casing in sequence to form a sandwich structure with two electrodes, then add 3 mol / L KOH electrolyte and encapsulate it into a CR2032 type button supercapacitor.

[0057] The enzymatically hydrolyzed lignin-based porous carbon material or supercapacitor prepared above was subjected to the following performance tests:

[0058] 1. Specific surface area: Tested using the TriStar II Plus-McSpecific Surface Area Analyzer.

[0059] 2. Constant current charge-discharge method: The constant current charge-discharge test of the button supercapacitor was carried out using the battery testing system (CT3001A) of Wuhan Landian Electronics Co., Ltd., and the specific capacitance at current densities of 1A / g and 20A / g was recorded. The retention rate of the specific capacitance at 20A / g current density relative to that at 1A / g current density was calculated.

[0060] 3. Yield of enzymatically hydrolyzed lignin-based porous carbon material: The yield of enzymatically hydrolyzed lignin-based porous carbon material is the percentage of the mass of the enzymatically hydrolyzed lignin-based porous carbon material to the mass of the modified enzymatically hydrolyzed lignin before carbonization.

[0061] Table 1 Performance Test Results

[0062]

[0063] As can be seen from Table 1, the most preferred embodiment of the present invention exhibits the best overall performance; that is, Example 1 has both high specific surface area and electrochemical performance, with a specific surface area of ​​2866.0 m². 2 The surface area (F / g) is close to the upper limit of the test data, indicating a highly developed pore structure. Simultaneously, its specific capacitance (321.7 F / g), rate retention (90.3%), and yield (61.2%) are also at a high level. This invention achieves a synergistic optimization of specific surface area, high rate stability, and yield, with a specific surface area reaching 2205.9-2866.0 m². 2 The specific capacitance can reach 312.6-325.5 F / g, the rate retention rate can reach 82.3-90.3%, and the yield can reach 59.1-61.2%.

[0064] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A method for preparing enzymatically hydrolyzed lignin-based porous carbon materials, characterized in that, Includes the following steps: 1) Tannic acid solution and chloroacetic acid solution are mixed and heated to react, yielding carboxylated tannic acid; 2) Add enzymatically hydrolyzed lignin, carboxylated tannic acid, and phenol to an alkaline solution and mix well. Adjust the pH to 9-11, add formaldehyde, and heat to react to obtain modified enzymatically hydrolyzed lignin. 3) The modified enzymatic hydrolyzed lignin is carbonized, the resulting carbonized material is crushed, an alkali activator is added, and it is activated at high temperature under an inert atmosphere. It is then crushed again to obtain enzymatic hydrolyzed lignin-based porous carbon material.

2. The method for preparing enzymatically hydrolyzed lignin-based porous carbon materials according to claim 1, characterized in that, In step 1), the molar ratio of tannic acid to chloroacetic acid is 1:6-10, preferably 1:6-8.

3. The method for preparing enzymatically hydrolyzed lignin-based porous carbon materials according to claim 1, characterized in that, In step 1), the tannic acid solution is prepared by dissolving tannic acid in water at 0-10℃ and adjusting the pH to 7.5-9 with an alkaline solution; the chloroacetic acid solution is prepared by dissolving chloroacetic acid in water at 0-10℃ and adjusting the pH to 7.5-9 with an alkaline solution.

4. The method for preparing enzymatically hydrolyzed lignin-based porous carbon materials according to claim 1, characterized in that, In step 1), the chloroacetic acid solution is added to the tannic acid solution dropwise over 1-2 hours; the heating reaction is carried out at 50-60°C for 3-5 hours.

5. The method for preparing enzymatically hydrolyzed lignin-based porous carbon materials according to claim 1, characterized in that, Step 1) further includes acidification, filtration, precipitation of the filtrate with acetone, filtration, washing, and drying of the precipitate.

6. The method for preparing enzymatically hydrolyzed lignin-based porous carbon materials according to claim 1, characterized in that, In step 2), the mass ratio of enzymatically hydrolyzed lignin, carboxylated tannic acid, phenol, and formaldehyde is 4-5:1.5-2.5:0.5-1:2.8-3.5, preferably 5:1.5-2:0.5-1:2.8-3.

5.

7. The method for preparing enzymatically hydrolyzed lignin-based porous carbon materials according to claim 1, characterized in that, In step 2), the enzymatically hydrolyzed lignin has a weight-average molecular weight of 1000-3000 and a phenolic hydroxyl content of 3-8 wt%.

8. The method for preparing enzymatically hydrolyzed lignin-based porous carbon materials according to claim 1, characterized in that, In step 2), the pH is adjusted to 9-11 using 5-10wt% NaOH solution or 5-10wt% hydrochloric acid; the heating reaction is carried out at 70-90℃ for 2-5 hours.

9. The method for preparing enzymatically hydrolyzed lignin-based porous carbon materials according to claim 1, characterized in that, In step 3), the mass ratio of the alkali activator to the carbonized material is 3-5:1; the alkali activator is selected from one or a combination of two of potassium hydroxide and sodium hydroxide.

10. A supercapacitor, characterized in that, Its electrodes comprise the enzymatically hydrolyzed lignin-based porous carbon material prepared by the preparation method according to any one of claims 1-9.

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