Coupling activation preparation method and application of biomass derived porous carbon material

Abstract

The invention relates to the technical field of preparation of activated carbon materials, in particular to a coupling activation preparation method and application of a biomass-derived porous carbon material. According to the coupling activation preparation method of the biomass-derived porous carbon material, the biomass-derived porous carbon material is prepared from a biomass raw material through the steps of fermentation, acid leaching reinforcement, hydrothermal carbonization, activation and acid pickling impurity removal. The biomass-derived porous activated carbon material prepared by the above steps is detected by a scanning electron microscope, and the biomass-derived porous activated carbon material is in a porous layer shape and has rich micropore and mesoporous structures; through electrochemical test experiment detection, the biomass derived porous activated carbon material has excellent capacitive performance, and when the current density is 0.5 A / g, the specific capacity value range is 200-400 F / g; the material also has good stability, the biomass derived porous activated carbon material is assembled into a symmetric supercapacitor, and after 10000 circles of stability tests, the retention rate of the specific capacitance of the symmetric supercapacitor can be maintained at about 96.4%.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of activated carbon materials, and particularly relates to a coupling activation preparation method and application of a biomass-derived porous carbon material. Background Art

[0002] Supercapacitors have high power density, fast charge and discharge capabilities, and extremely long cycle life (up to hundreds of thousands of times) in energy storage, and are particularly suitable for short-term high-power demand scenarios, such as electric vehicle acceleration and power grid frequency modulation. With the breakthrough of technologies such as nanomaterials and composite electrodes, their energy density has been continuously improved, and they have broad application prospects in the fields of renewable energy storage, rail transit energy recovery, and industrial backup power supplies in the future. High-end carbon electrode materials are the core components of supercapacitors, and their pore structure, specific surface area, and conductivity directly determine the device performance. However, there are still shortcomings in the domestic preparation technology of high-purity and high-consistency carbon materials, relying on imports. This field involves precise carbonization activation processes and nanostructure control technologies. In recent years, domestic universities and enterprises have accelerated research through the development of biomass-based porous carbon, graphene composite electrodes, etc., but the industrialization level still needs to be improved.

[0003] Among them, Patent CN117550602A discloses a petroleum-based activated carbon and its preparation method. Using potassium hydroxide and potassium carbonate in a ratio of 4:1 as a composite activator, with a carbon-alkali ratio (mass ratio of petroleum coke to composite activator) of 1:5, a petroleum-based activated carbon precursor is obtained through pre-activation, activation, washing, and drying in sequence. The obtained petroleum-based activated carbon precursor is impregnated in a metal salt solution, and after solid-liquid separation and drying, the petroleum-based activated carbon is obtained, with a specific surface area of up to 2813 m 2 / g, a microporosity of up to 99%, and a saturated adsorption capacity of up to 627 mg / g. However, the disadvantages of this patent are as follows: Commercial petroleum-based activated carbon relies on fossil raw materials, is non-renewable, faces resource depletion and carbon emission problems, and the amount of activator used is large, accompanied by environmental pollution and an increase in activator cost.

[0004] The raw material of biomass-based activated carbon is biomass and can be regenerated. The current mainstream technology requires strong alkali activation. In order to realize the preparation of high-performance carbon materials using waste biomass (or by-products), Patent CN111017925A discloses the preparation and application of a novel porous carbon material with high energy storage performance. By directly activating waste Sanhua liquor lees, the obtained carbon material is used in a supercapacitor, and a specific capacitance of 463 F / g can be obtained, effectively achieving the transformation of waste into treasure. However, this patent also has the problem of excessive alkali usage (the mass ratio of carbon precursor to alkaline inorganic substance is 1:4 - 5), which will lead to an increase in activator cost, an increase in the equipment corrosion rate, and an increase in wastewater treatment cost, etc.

[0005] Therefore, the focus can be on the directional conversion technology of non-grain biomass: how to use agricultural waste such as straw and fruit shells to reduce the dosage of activators during the activation process of carbon materials through effective design and synthesis means, reduce costs and pollution, and prepare biomass carbon materials with porous structures, and effectively improve the electrochemical performance of biomass carbon materials is the problem that needs to be solved currently. Summary of the Invention

[0006] The main object of the present invention is to provide a coupling activation preparation method and application of biomass-derived porous carbon materials, aiming to improve the technical problems such as the increase in the cost of activators, the increase in the corrosion rate of equipment, and environmental pollution caused by the use of more activators in the existing porous carbon preparation process.

[0007] To achieve the above object, the present invention proposes a coupling activation preparation method of biomass-derived porous carbon materials, which is prepared from biomass raw materials through the steps of fermentation, acid leaching strengthening, hydrothermal carbonization, activation, and acid washing for impurity removal.

[0008] Preferably, it includes the following steps:

[0009] (1) Fermentation: The biomass raw materials are cleaned, dried, crushed and sterilized, cooled to room temperature, and then a composite enzyme agent and urea are added for sealed fermentation to obtain fermented biomass.

[0010] (2) Acid leaching strengthening: The fermented biomass obtained in step (1) is dried, crushed and mixed with an acid solution, and after strengthening treatment, it is dried to obtain acid-leached biomass.

[0011] (3) Hydrothermal carbonization: The acid-leached biomass obtained in step (2) is dispersed and placed in a hydrothermal autoclave, and hydrothermal reaction is carried out in a heating device. The hydrothermal reaction temperature is 160-190 °C, and the reaction time is 4-8 h. The obtained product is washed with deionized water until neutral and then dried to obtain a carbon precursor.

[0012] (4) Activation: The carbon precursor obtained in step (3) and an alkali activator are uniformly dispersed in deionized water, stirred, dried, and then calcined and activated at 600-1000 °C for 1-4 h.

[0013] (5) Acid washing for impurity removal: After the product obtained in step (4) undergoes acid leaching, washing until neutral, and drying processes, the biomass-derived porous carbon materials are obtained.

[0014] Preferably, the biomass raw materials include at least one of straw, wood waste, bagasse, passion fruit shell, schizandra propinqua (Wall.) Baill. shell, coconut shell, nut shell, or peanut shell.

[0015] Preferably, the composite enzyme agent in step (1) includes at least one of cellulase, xylanase, ligninase, glucosidase, pectinase, and koji.

[0016] The total mass of the complex enzyme agent and urea in step (1) is 0.1-1.5% of the mass of the biomass raw material.

[0017] Preferably, the fermentation conditions in step (1) are 25-40°C, and the fermentation time is 3-30 days.

[0018] Preferably, the acid solution in step (2) is phosphoric acid with a concentration of 1-3 mol / L or sulfuric acid with a concentration of 1-3 mol / L; the mass ratio of the acid solution to the fermented biomass is 1:(5-10).

[0019] Preferably, the strengthening treatment process in step (2) is to keep the temperature constant at 70-90°C for 4-48 h under airtight conditions.

[0020] Preferably, the alkali activator in step (4) includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, sodium chloride, sodium sulfate or potassium carbonate; the mass ratio of the carbon precursor to the alkali activator is 1∶(0.5-2).

[0021] Preferably, the acid leaching in step (5) is carried out by soaking in a hydrochloric acid solution with a concentration of 1-3 mol / L, and the soaking time is 4-24 h.

[0022] In addition, the present invention also provides an application of the biomass-derived porous carbon material prepared by the coupled activation preparation method of the above biomass-derived porous carbon material in a supercapacitor.

[0023] Compared with the prior art, the coupled activation preparation method of the biomass-derived porous carbon material of the present invention has the following beneficial effects:

[0024] 1. In this solution, waste biomass is used as the raw material, and after steps such as fermentation, acid leaching strengthening, hydrothermal carbonization, activation, and acid washing for impurity removal, a biomass-derived porous activated carbon material is prepared. After being detected by scanning electron microscopy, the obtained biomass-derived porous activated carbon material is in a porous layer shape and has a rich microporous and mesoporous structure; after being detected by electrochemical test experiments, the obtained biomass-derived porous activated carbon material has excellent capacitance performance. When the current density is 0.5 A / g, the specific capacitance value ranges from 200 to 400 F / g; this material also has good stability. When the biomass-derived porous activated carbon material with excellent performance is assembled into a symmetric supercapacitor, after 10,000 cycles of stability testing, the retention rate of its specific capacitance can be maintained at about 96.4%.

[0025] 2. In the coupled activation preparation method of the above biomass-derived porous carbon material, waste biomass is used as the precursor, which has low cost and is easy to scale up production.

[0026] 3. Through processes such as biomass fermentation and phosphoric acid impregnation strengthening, this solution has greatly reduced the addition ratio of subsequent alkali activation, reduced the usage amount of the activator by more than 50%, significantly reduced the cost, and reduced environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other relevant drawings can also be obtained based on these drawings.

[0028] Figure 1 SEM image of the biomass-derived porous carbon material prepared in Example 1 of the present invention;

[0029] Figure 2 Cyclic voltammogram of the biomass-derived porous carbon material prepared in Example 1 of the present invention.

[0030] The realization of the purpose of the present application, functional features and advantages will be further described in conjunction with the embodiments and with reference to the drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0032] In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of the technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0033] A coupling activation preparation method for a biomass-derived porous carbon material, comprising the following steps:

[0034] (1) Fermentation: The biomass raw material is cleaned, dried (at a temperature of 90 - 100 °C), pulverized, and then sterilized with steam / boiling water for 1 - 12 h. After cooling to room temperature, a composite enzyme agent and urea are added for sealed fermentation to obtain fermented biomass, where the fermentation conditions are 25 - 40 °C and the fermentation time is 3 - 30 days; the biomass raw material includes at least one of straw, wood waste, bagasse, passion fruit shell, schizandra fruit shell, coconut shell, nut shell, or peanut shell; the composite enzyme agent includes at least one of cellulase, xylanase, ligninase, glucosidase, pectinase, and koji; the total mass of the composite enzyme agent and urea is 0.1 - 1.5% of the mass of the biomass raw material;

[0035] (2) Acid leaching enhancement: The fermented biomass from step (1) is dried and pulverized into powder, then mixed with an acid solution, and subjected to enhancement treatment at a constant temperature of 70 - 90 °C for 4 - 48 h under sealed conditions, and the acid-leached biomass is obtained after drying; the acid solution is phosphoric acid with a concentration of 1 - 3 mol / L or sulfuric acid with a concentration of 1 - 3 mol / L; the mass ratio of the acid solution to the fermented biomass is 1:(5 - 10);

[0036] (3) Hydrothermal carbonization: The acid-leached biomass from step (2) is dispersed and placed in a hydrothermal reactor, and a hydrothermal reaction is carried out in a heating device. The hydrothermal reaction temperature is 160 - 190 °C, and the reaction time is 4 - 8 h. The obtained product is washed with deionized water until neutral and then dried to obtain a carbon precursor;

[0037] (4) Activation: The carbon precursor from step (3) and an alkali activator are uniformly mixed and dispersed in deionized water, stirred for 30 - 60 min, and then dried to remove moisture, and then calcined and activated at 600 - 1000 °C for 1 - 4 h, with a heating rate of 2 - 10 °C / min; the alkali activator includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, sodium chloride, sodium sulfate, or potassium carbonate; the mass ratio of the carbon precursor to the alkali activator is 1∶(0.5 - 2);

[0038] (5) Acid washing for impurity removal: The product obtained in step (4) is acid-leached, washed with deionized water until neutral, and after the drying process, a biomass-derived porous carbon material is obtained. Among them, it is soaked in a hydrochloric acid solution with a concentration of 1 - 3 mol / L for 4 - 24 h.

[0039] In addition, the present invention also proposes an application of a biomass-derived porous carbon material prepared by a coupling activation preparation method of a biomass-derived porous carbon material in a supercapacitor.

[0040] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0041] Comparative Example 1

[0042] Washing of passion fruit peel: Take the passion fruit peel raw material for washing, and obtain the dried peel after drying; Calcinate and carbonize the dried peel in a nitrogen atmosphere at 500 °C for 2 h, and the obtained product is washed with deionized water until neutral and dried to obtain a carbon precursor; The above carbon precursor and an alkali activator (sodium hydroxide) are uniformly mixed and dispersed in deionized water according to a mass ratio of 1:1, the water is removed after drying, and it is calcined and activated at 700 °C for 2 h. The obtained product is leached in a hydrochloric acid solution with a concentration of 2 mol / L for 12 h, and then washed with deionized water until neutral and dried after treatment to obtain the activated porous activated carbon material.

[0043] Example 1

[0044] A coupling activation preparation method of a biomass-derived porous carbon material, comprising the following steps:

[0045] (1) Fermentation: The biomass raw material (passion fruit shell) is sterilized after being washed, dried and crushed, and after cooling to room temperature, 0.9% of a composite enzyme agent (cellulase, ligninase, glucosidase with a mass ratio of 2:1:1) and 0.12% of urea are added for sealed fermentation to obtain fermented biomass. The fermentation conditions are 28 °C and the fermentation time is 15 days;

[0046] (2) Acid leaching enhancement: The fermented biomass in step (1) is dried and crushed into powder, and then mixed with an acid solution (2 mol / L phosphoric acid), and subjected to strengthening treatment at 80 °C for 8 h under sealed conditions, and the acid-leached biomass is obtained after drying; The mass ratio of the acid solution to the fermented biomass is 1:8;

[0047] (3) Hydrothermal carbonization: The acid-leached biomass in step (2) is dispersed and placed in a hydrothermal autoclave, and a hydrothermal reaction is carried out in an oven. The hydrothermal reaction temperature is 180 °C and the reaction time is 6 h. The obtained product is washed with deionized water until neutral and then dried to obtain a carbon precursor;

[0048] (4) Activation: The carbon precursor in step (3) and an alkali activator (sodium hydroxide) are uniformly mixed and dispersed in deionized water, stirred for 30 min and then dried to remove water, and then calcined and activated at 700 °C for 2 h in a nitrogen atmosphere, and the heating rate is 5 °C / min; The mass ratio of the carbon precursor to the alkali activator is 1:1;

[0049] (5) Pickling and impurity removal: The product obtained in step (4) is leached in a hydrochloric acid solution with a concentration of 2 mol / L for 12 h, washed with deionized water until neutral, and dried to obtain the biomass-derived porous carbon material.

[0050] Example 2

[0051] In this comparative example, all the preparation steps and parameters are the same as those in Example 1, except that: the biomass raw material in step (1) is bagasse.

[0052] Example 3

[0053] In this comparative example, all the preparation steps and parameters are the same as those in Example 1, except that: the biomass raw material in step (1) is the shell of Akebia trifoliata.

[0054] Comparative Example 2

[0055] In this comparative example, all the preparation steps and parameters are the same as those in Example 1, except that: the fermentation process in step (1) is cancelled, that is, the sterilized passion fruit shell is directly subjected to the acid leaching and strengthening step.

[0056] Comparative Example 3

[0057] In this comparative example, all the preparation steps and parameters are the same as those in Example 1, except that: the acid leaching and strengthening process in step (2) is cancelled, and the fermented biomass is directly hydrothermally carbonized after drying and pulverizing.

[0058] Comparative Example 4

[0059] In this comparative example, all the preparation steps and parameters are the same as those in Example 1, except that: the hydrothermal carbonization in step (3) is replaced with a conventional carbonization process, and the specific carbonization parameters are calcined and carbonized at 500 °C for 2 h, and the heating rate is 4 °C / min.

[0060] The porous carbon materials prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to the following performance tests, and the specific test results are shown in the following table:

[0061]

[0062] Note: 1. In order to prove the application of the porous carbon material as a supercapacitor electrode material, the prepared porous carbon material was subjected to a constant current charge-discharge test in a 6 mol / L KOH electrolyte to obtain the above specific capacitance (current density is 0.5 A / g).

[0063] 2. In order to prove that the porous carbon material has a good capacitance retention rate, the prepared porous carbon material was assembled into a symmetric supercapacitor and subjected to 10,000 constant current charge-discharge tests at a current density of 10 A / g.

[0064] From the test results of Comparative Example 1 in the above table, it can be seen that in the conventional pre-carbonization and calcination activation process, the dosage of the activator is large, and the performance of the prepared porous carbon material / supercapacitor is average.

[0065] For the porous carbon materials obtained in Examples 1-3 of this solution, the specific surface area is maintained at 2924-3095 m 2In the range of / g, it has a rich microporous and mesoporous structure. The supercapacitor prepared from this porous carbon material has a high specific capacitance, and the retention rate of specific capacitance is also high after 10,000 cycles of stability testing. At the same time, in order to prove that the porous carbon material obtained after activation has a richer pore structure, the biomass-derived porous carbon material obtained in step (5) of Example 1 was subjected to scanning electron microscope detection, as Figure 1 shown, a more abundant and regular porous structure was obtained on the pore structure of the biomass-derived porous carbon material. In order to prove that the porous carbon material of this solution has good rate performance, cyclic voltammetry testing was carried out on Example 1, and the test results are as Figure 2 shown. It can still maintain a good rectangular shape at a large scan rate of 100 mV / s, indicating that the carbon material obtained in Example 1 has good rate performance.

[0066] From the comparison results of Comparative Examples 2-3 and Example 1, it can be seen that when step (1) is cancelled, the specific surface area and specific capacitance of the porous carbon material / supercapacitor will decrease. When step (2) is cancelled, the specific surface area, specific capacity and specific capacitance of the porous carbon material / supercapacitor will all decrease.

[0067] From the comparison results of Comparative Example 4 and Example 1, it can be seen that when the hydrothermal carbonization process is not used in step (3), the specific surface area, specific capacity and specific capacitance of the porous carbon material / supercapacitor also decrease.

[0068] And through multiple experiments, it is found that the mass ratio of the carbon precursor and the alkali activator in this solution can be as low as 1:0.5 at the lowest. Even when the dosage of the alkali activator is low, the performance of the prepared porous carbon material / supercapacitor is also good, and the specific surface area is maintained at about 2563 m 2 / g, the specific capacity of the supercapacitor can be maintained at about 278 F / g, and the retention rate of specific capacitance can be maintained at about 87%.

[0069] Example 4

[0070] In this example, all the preparation steps and parameters are the same as those in Example 1, except that the type of composite enzyme agent used in step (1) is different. Specifically:

[0071]

[0072] The porous carbon material prepared in Example 4 was subjected to performance testing, and the specific test results are shown in the following table:

[0073]

[0074] As shown in the test data in the above table, compared with the conventional pre-carbonization and calcination activation processes of Comparative Example 1, different composite enzyme agents in this solution can improve the specific surface area, specific capacity, and specific capacitance of the porous carbon material / supercapacitor. Generally speaking, when the composite enzyme agent for biomass fermentation is a combination of cellulase, ligninase, and glucosidase with a mass ratio of 2:1:1, the improvement effect on the various properties of the porous carbon material / supercapacitor is the best.

[0075] Example 5

[0076] In this example, all the preparation steps and parameters are the same as those in Example 1, except that the fermentation time in step (1) is different. Specifically:

[0077]

[0078]

[0079] The porous carbon material prepared in Example 5 was subjected to performance testing. The specific test results are shown in the following table:

[0080]

[0081] As shown in the test data in the above table, the biomass fermentation time has a great influence on the performance of the porous carbon material. Among them, when the biomass fermentation time is 5 - 25 days, it is the preferred fermentation time for this method (15 days is the best fermentation time).

[0082] Example 6

[0083] In this example, all the preparation steps and parameters are the same as those in Example 1, except that the strengthening treatment parameters in step (1) are different. Specifically:

[0084] Reinforcement treatment parameters Example 1 Reinforcement treatment was carried out by phosphoric acid leaching at a constant temperature of 80 °C for 8 h Example 6-1 Reinforcement treatment was carried out by phosphoric acid leaching at a constant temperature of 70 °C for 8 h Example 6-2 Reinforcement treatment was carried out by phosphoric acid leaching at a constant temperature of 80 °C for 12 h Example 6-3 Reinforcement treatment was carried out by phosphoric acid leaching at a constant temperature of 90 °C for 8 h Example 6-4 Reinforcement treatment was carried out by sulfuric acid leaching at a constant temperature of 80 °C for 8 h

[0085] The porous carbon material prepared in Example 6 was subjected to performance testing. The specific test results are shown in the following table:

[0086]

[0087] As shown in the test data in the above table, different strengthening treatment parameters also have an impact on the performance of the porous carbon material. Among them, the acid for acid leaching is preferably phosphoric acid, and the strengthening parameters are preferably constant temperature strengthening at 70 - 80 °C for 8 - 12 h. The specific surface area of the porous carbon material can be maintained above 3020 m 2 / g, and the retention rates of the specific capacity and specific capacitance are also relatively high.

[0088] Example 7

[0089] In this embodiment, all the preparation steps and parameters are the same as those in Embodiment 1, except that the type of alkali activator used in step (1) is different. Specifically:

[0090]

[0091] The porous carbon material prepared in Embodiment 7 was subjected to performance testing. The specific test results are shown in the following table:

[0092]

[0093]

[0094] As shown in the test data in the above table, the use of different composite enzyme agents can improve the performance of the porous carbon material / supercapacitor. However, when sodium hydroxide is used as the alkali activator, the improvement effect on the performance of the porous carbon material / supercapacitor is the best.

[0095] Embodiment 8

[0096] In this embodiment, all the preparation steps and parameters are the same as those in Embodiment 1, except that the calcination parameters during activation in step (1) are different. Specifically:

[0097] Calcination parameters during activation Example 1 Calcination activation was carried out at 700 °C for 2 h, and the heating rate was 5 °C / min Example 8-1 Calcination activation was carried out at 500 °C for 3 h, and the heating rate was 5 °C / min Example 8-2 Calcination activation was carried out at 600 °C for 3 h, and the heating rate was 3 °C / min Example 8-3 Calcination activation was carried out at 700 °C for 2 h, and the heating rate was 8 °C / min Example 8-4 Calcination activation was carried out at 800 °C for 2 h, and the heating rate was 4 °C / min Example 8-5 Calcination activation was carried out at 1000 °C for 1 h, and the heating rate was 6 °C / min

[0098] The porous carbon material prepared in Embodiment 8 was subjected to performance testing. The specific test results are shown in the following table:

[0099]

[0100] As shown in the test data in the above table, the calcination parameters during activation are preferably calcined and activated at 600 - 800 °C for 2 - 3 h, and the heating rate is preferably 3 - 8 °C / min. The specific surface area of the porous carbon material can be maintained above 2800 m 2 / g, the specific capacitance of the supercapacitor can be maintained above 300 F / g, and the retention rate of the specific capacitance can be maintained above 86%.

[0101] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made using the content of the specification of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A coupled activation preparation method of a biomass-derived porous carbon material, characterized in that, It is prepared from biomass raw materials through the steps of fermentation, acid leaching strengthening, hydrothermal carbonization, activation and acid washing for impurity removal.

2. The coupled activation preparation method of a biomass-derived porous carbon material according to claim 1, characterized in that, It includes the following steps: (1) Fermentation: The biomass raw materials are cleaned, dried, crushed and sterilized, cooled to room temperature, and then a composite enzyme agent and urea are added for sealed fermentation to obtain fermented biomass. (2) Acid leaching strengthening: The fermented biomass obtained in step (1) is dried, crushed and mixed with an acid solution, and after strengthening treatment, it is dried to obtain acid-leached biomass. (3) Hydrothermal carbonization: The acid-leached biomass obtained in step (2) is dispersed and placed in a hydrothermal autoclave, and hydrothermal reaction is carried out in a heating device. The hydrothermal reaction temperature is 160 - 190 °C, and the reaction time is 4 - 8 h. The obtained product is washed with deionized water until neutral and then dried to obtain a carbon precursor. (4) Activation: The carbon precursor obtained in step (3) and an alkali activator are uniformly dispersed in deionized water, stirred, dried, and then calcined and activated at 600 - 1000 °C for 1 - 4 h. (5) Acid washing for impurity removal: After the product obtained in step (4) undergoes acid leaching, washing until neutral and drying processes, the biomass-derived porous carbon material is obtained.

3. The coupled activation preparation method of a biomass-derived porous carbon material according to claim 1 or 2, characterized in that, The biomass raw materials include at least one of straw, wood waste, bagasse, passion fruit shells, August-fruit shells, coconut shells, nut shells or peanut shells.

4. The coupled activation preparation method of a biomass-derived porous carbon material according to claim 2, characterized in that: The composite enzyme agent in step (1) includes at least one of cellulase, xylanase, ligninase, glucosidase, pectinase and koji. The total mass of the composite enzyme agent and urea in step (1) is 0.1 - 1.5% of the mass of the biomass raw materials.

5. The coupled activation preparation method of a biomass-derived porous carbon material according to claim 2, characterized in that: The fermentation conditions in step (1) are 25 - 40 °C, and the fermentation time is 3 - 30 days.

6. The coupled activation preparation method of a biomass-derived porous carbon material according to claim 2, characterized in that: The acid solution in step (2) is phosphoric acid with a concentration of 1 - 3 mol / L or sulfuric acid with a concentration of 1 - 3 mol / L; the mass ratio of the acid solution to the fermented biomass is 1:(5 - 10).

7. A coupled activation preparation method of a biomass-derived porous carbon material according to claim 2, characterized in that, The strengthening treatment process in step (2) is to keep the temperature constant at 70 - 90 °C for 4 - 48 h under sealed conditions.

8. The coupling activation preparation method of a biomass-derived porous carbon material according to claim 2, characterized in that, The alkali activator in step (4) includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, sodium chloride, sodium sulfate or potassium carbonate; the mass ratio of the carbon precursor to the alkali activator is 1:(0.5 - 2).

9. The coupled activation preparation method of a biomass-derived porous carbon material according to claim 2, characterized in that: The acid leaching in step (5) is carried out by soaking with a hydrochloric acid solution with a concentration of 1 - 3 mol / L, and the soaking time is 4 - 24 h.

10. Application of a biomass-derived porous carbon material prepared by a coupling activation preparation method of the biomass-derived porous carbon material according to any one of claims 1 - 9 in a supercapacitor.

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