Reconstructed biomass precursor material with high mechanical strength and high density as well as preparation method and application thereof
By pre-embedding and wet grinding of water molecules in biomass materials, the problem of insufficient mechanical strength and density of biomass materials is solved, and efficient pore size regulation and thermal stability of carbon materials are achieved, which is suitable for the preparation of high-performance biomass carbon.
Patent Information
- Application Number
- CN202411916283.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-24
- Publication Date
- 2025-05-13
AI Technical Summary
The prior art is difficult to effectively improve the mechanical strength and density of biomass materials with high cellulose proportion, which leads to difficulty in regulating the pore size of carbon materials, and the high energy consumption and environmental pollution in the thermal densification and acid treatment processes.
By soaking natural biomass in ultrapure water and heating, impurities and soluble organic matter on the surface are removed, and water molecules are pre-embedded and wet-milled in the polytetrafluoroethylene liner, and finally, vacuum drying is obtained to obtain a reconstructed biomass precursor material with high mechanical strength and high density.
It significantly improves the thermal stability and chemical stability of biomass precursors, improves the reaction efficiency during carbonization, improves the corrosion resistance of the carbon skeleton, and maintains the complete block structure characteristics.
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Figure CN119979194A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of biomass precursor preparation, and in particular to a reconstructed biomass precursor material with high mechanical strength and high density, and a preparation method and application thereof. Background Art
[0002] Kuraray activated carbon has become the preferred electrode material for supercapacitors due to its excellent structural stability and suitable pore structure. At present, biomass raw materials for preparing activated carbon have the advantages of abundant sources, economy, environmental protection and renewability. It is well known that raw materials with high mechanical strength are helpful to prepare carbon materials with uniform pore size distribution and improve the adsorption and storage capacity of ions. However, most biomass materials with a high proportion of cellulose usually show soft characteristics, which makes it difficult to achieve precise control of the pore size of the prepared carbon materials. At present, there are three main strategies to improve the mechanical strength and density of raw materials by regulating the morphology and physical properties of biomass: thermal densification treatment, chemical modification and material composite. Thermal densification treatment is to improve the intrinsic properties of biomass by using temperature field and pressure field. This strategy can significantly improve the tap density of biomass raw materials and optimize their mechanical properties and structural stability. However, the densification process requires a lot of energy for heating and compressing raw materials, resulting in excessive energy consumption and a significant increase in cost. Acid treatment improves the mechanical strength of biomass by adjusting the molecular chain structure of biomass. This strategy can adjust the degradation reaction of biomass components, change its natural structure and composition, and thus improve the mechanical properties of the material. However, the acid treatment process will produce a large amount of acidic wastewater, causing environmental pollution, and hot pressing treatment is required to achieve the densification of biomass. Biomass composite materials combine biomass with polymer resin materials, using the high strength characteristics of polymer resin materials to improve the mechanical properties of raw materials. However, the process is relatively complicated, and poor compatibility may lead to poor uniformity of the composite material, affecting the final performance of the material. Summary of the invention
[0003] In order to solve the above-mentioned technical problems, the purpose of the present invention is to provide a reconstructed biomass precursor material with high mechanical strength and high density, and a preparation method and application thereof, which effectively realizes the mechanical strength and density of the biomass precursor material, significantly improves the thermal stability and chemical stability of the ramie precursor, improves the reaction efficiency during the carbonization process, and effectively improves the corrosion resistance of the carbon skeleton, better maintains the complete block structure characteristics, and solves the problem of poor skeleton continuity of carbon materials prepared from biomass raw materials with a high proportion of cellulose.
[0004] The technical solution of the present invention to solve the above technical problems is as follows: a method for preparing a reconstructed biomass precursor material with high mechanical strength and high density is provided, comprising the following steps:
[0005] The natural biomass is placed in ultrapure water, soaked at 85-95°C for 3-9 hours, washed and dried to obtain a biomass raw material; the biomass raw material is then placed in a polytetrafluoroethylene liner and ultrapure water is added, heated to 180-240°C and kept warm for 6 hours, cooled to room temperature, washed, and wet-milled at 300-500r / min for 6 hours with ultrapure water, and vacuum filtered and vacuum dried to obtain a reconstructed biomass precursor material with high mechanical strength and high density.
[0006] Furthermore, the mass volume ratio of natural biomass to ultrapure water is 25 g:1000 mL; the mass volume ratio of biomass raw materials to ultrapure water is 1 g:30 mL.
[0007] Furthermore, the natural biomass is ramie.
[0008] Furthermore, after cleaning, the product was vacuum dried at 120° C. for 24 h.
[0009] Further, the mixture was dried in vacuum at 120°C for 12 h.
[0010] The method firstly soaks the natural biomass in ultrapure water for heating to remove impurities on the surface of the natural biomass, then heats and insulates the ultrapure water in a polytetrafluoroethylene liner to achieve sufficient pre-embedding of water molecules, then washes away soluble organic matter on the surface of the material, and finally obtains a disordered biomass precursor after wet grinding and vacuum drying.
[0011] The present invention also provides a reconstructed biomass precursor material with high mechanical strength and high density obtained by the preparation method of the reconstructed biomass precursor material with high mechanical strength and high density.
[0012] The present invention also provides a method for preparing highly stable biochar, comprising the following steps:
[0013] (1) crushing and screening the above-mentioned reconstructed biomass precursor material with high mechanical strength and high density, and then evenly distributing the biomass precursor material in a nickel boat and placing it in a high-temperature tube furnace, heating it to 400° C. for 1 hour under an argon atmosphere, cooling it to room temperature, and grinding it to obtain a biomass carbonization precursor;
[0014] (2) mixing the biomass carbonization precursor obtained in step (1) and potassium hydroxide, grinding at 70° C., and then evenly distributing the mixture in a nickel boat and placing the mixture in a high-temperature tube furnace. In an argon atmosphere, heating the mixture to 700° C. for reaction for 1 h, cooling the mixture to room temperature, and placing the mixture in a hydrochloric acid solution for stirring and soaking, washing the mixture until it is neutral, and then adding ultrapure water for wet grinding at 200-400 r / min for 2 h to obtain a dispersion.
[0015] (3) The dispersion obtained in step (2) is cleaned and vacuum dried, then evenly distributed in a graphite crucible and placed in a high-temperature tube furnace. In an argon atmosphere, the temperature is raised to 500° C. and kept for 1 hour, and then cooled to room temperature to obtain highly stable biochar.
[0016] Furthermore, in step (2), the mass ratio of the biomass carbonization precursor to potassium hydroxide is 0.5 g:0.75-1.25 g.
[0017] Furthermore, in step (2), the mixture is stirred and immersed in a 1M hydrochloric acid solution for 8 hours, and then washed with ultrapure water at 95° C. until it becomes neutral.
[0018] Furthermore, in steps (1) to (3), when heating, the heating rate is 4°C / min and the gas flow rate is 40sccm.
[0019] Further, in step (3), vacuum drying is performed at 120° C. for 12 h.
[0020] The present invention also provides high-stability biochar prepared by the above-mentioned preparation method of high-stability biochar.
[0021] The present invention also provides the use of the above-mentioned highly stable biomass carbon in preparing supercapacitor electrode materials.
[0022] The method for preparing the supercapacitor electrode material comprises the following steps:
[0023] High-stability biochar, conductive carbon black and polyvinylidene fluoride binder were mixed evenly in N-methylpyrrolidone to obtain slurry; then the slurry was evenly coated on carbon-coated aluminum foil and rolled to obtain a compaction density of 0.615 g / cm -3 active electrode.
[0024] Furthermore, the mass ratio of the high-stability biochar, the conductive carbon black and the polyvinylidene fluoride binder is 80-90:5-10:5-10.
[0025] The present invention has the following beneficial effects:
[0026] When preparing reconstructed biomass precursor materials with high mechanical strength and high density, the subcritical water molecules can effectively remove the organic components in the biomass raw materials and realize the pre-embedding of water molecules by virtue of their strong dissolving and driving effects. Under the action of mechanical grinding, the natural ordered structure of the biomass is destroyed, resulting in a decrease in its crystallinity and order. During capillary evaporation, the abundant hydroxyl groups on the cellulose chains can form a strong hydrogen bond network, reduce the porosity inside the raw materials, and improve the thermal stability and chemical stability of the biomass precursor. The disordered biomass precursor effectively improves the corrosion resistance of the carbon skeleton. The highly stable porous biomass carbon-based supercapacitor prepared by the present invention exhibits a high power density (47.94kWkg-1 ) and high energy density (28.11Wh kg -1 ), which is significantly better than commercial activated carbon-based supercapacitors (40.86kW kg -1 and 12.67Wh kg -1 ). Therefore, this molecular reconstruction strategy can pave the way for the preparation of highly stable porous carbon from soft biomass materials and promote the application of soft biomass materials in the preparation of commercial activated carbon. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 is a photograph of the volume change of the ramie precursor during capillary evaporation in Example 1;
[0028] Figure 2 The molecular reconstruction mechanism of three-dimensional disordered ramie precursor;
[0029] Figure 3 Thermogravimetric analysis results of the ramie precursor and natural ramie obtained in Example 1;
[0030] Figure 4 This is a schematic diagram of the microscopic morphology of the highly stable biochar obtained in Example 1;
[0031] Figure 5 The electrochemical performance results of the supercapacitor obtained in Example 1;
[0032] Figure 6 The CV curves and cycle life results of the supercapacitor obtained in Example 1 at different operating temperatures. DETAILED DESCRIPTION
[0033] The principles and features of the present invention are described below, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. If no specific conditions are specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.
[0034] Example 1
[0035] A reconstructed biomass precursor material with high mechanical strength and high density, the preparation method of which comprises the following steps:
[0036] Place 25g of natural ramie in 1000mL of ultrapure water, soak it at 90℃ for 6h, wash it and vacuum dry it at 120℃ for 24h to obtain the biomass raw material; then place 1g of the biomass raw material in a polytetrafluoroethylene liner and add 30mL of ultrapure water, heat it to 190℃ and keep it warm for 6h, cool it to room temperature, wash it with ultrapure water, add ultrapure water and wet grind it at 400r / min for 6h, vacuum filter it, and vacuum dry it at 120℃ for 12h to obtain a reconstructed biomass precursor material with high mechanical strength and high density.
[0037] A highly stable biochar, the preparation method of which comprises the following steps:
[0038] (1) The above-mentioned reconstructed biomass precursor material with high mechanical strength and high density was crushed and sieved, and then 2 g of the biomass precursor material was evenly distributed in a nickel boat and placed in a high-temperature tube furnace. In an argon atmosphere, the temperature was increased to 400° C. at a heating rate of 4° C. / min and a gas flow rate of 40 sccm, and the temperature was kept at 400° C. for 1 h, cooled to room temperature, and ground to obtain a biomass carbonization precursor;
[0039] (2) 0.5 g of the biomass carbonization precursor obtained in step (1) and 1 g of potassium hydroxide were shaken and mixed, ground at 70° C., and then evenly distributed in a nickel boat and placed in a high-temperature tube furnace. In an argon atmosphere, the temperature was raised to 700° C. at a heating rate of 4° C. / min and a gas flow rate of 40 sccm for reaction for 1 h. The mixture was cooled to room temperature, stirred and soaked in a 1 M hydrochloric acid solution for 8 h, washed with ultrapure water at 95° C. until neutral, and then added with ultrapure water for wet grinding at 300 r / min for 2 h to obtain a dispersion;
[0040] (3) The dispersion obtained in step (2) is washed, vacuum dried at 120° C. for 12 h, and then evenly distributed in a graphite crucible and placed in a high-temperature tube furnace. In an argon atmosphere, the temperature is increased to 500° C. at a heating rate of 4° C. / min and a gas flow rate of 40 sccm, and the temperature is maintained for 1 h. The dispersion is then cooled to room temperature to obtain highly stable biochar.
[0041] The method for preparing a supercapacitor electrode material comprises the following steps:
[0042] 85 parts of high-stable biochar, 8 parts of conductive carbon black and 8 parts of polyvinylidene fluoride binder were mixed evenly in N-methylpyrrolidone to obtain slurry; then the slurry was evenly coated on carbon-coated aluminum foil and rolled to obtain a compacted density of 0.615 g / cm -3 active electrode.
[0043] Subsequently, the electrode sheet was dried in a vacuum oven at 120°C for 12 hours and compacted on a roller press at a pressure of 6 MPa; rectangular electrodes with a length of 50 mm and a width of 44 mm were made by cold light processing; finally, two electrodes with the same loading amount were assembled into a soft-pack supercapacitor using 1M Et4NBF4 / AN as the electrolyte.
[0044] Example 2
[0045] A reconstructed biomass precursor material with high mechanical strength and high density, the preparation method of which comprises the following steps:
[0046] Place 25g of natural ramie in 1000mL of ultrapure water, soak it at 85℃ for 3h, wash it and vacuum dry it at 120℃ for 24h to obtain the biomass raw material; then place 1g of the biomass raw material in a polytetrafluoroethylene liner and add 30mL of ultrapure water, heat it to 180℃ and keep it warm for 6h, cool it to room temperature, wash it with ultrapure water, add ultrapure water and wet grind it at 500r / min for 6h, vacuum filter it, and vacuum dry it at 120℃ for 12h to obtain a reconstructed biomass precursor material with high mechanical strength and high density.
[0047] A highly stable biochar, the preparation method of which comprises the following steps:
[0048] (1) The above-mentioned reconstructed biomass precursor material with high mechanical strength and high density was crushed and sieved, and then 2 g of the biomass precursor material was evenly distributed in a nickel boat and placed in a high-temperature tube furnace. In an argon atmosphere, the temperature was increased to 400° C. at a heating rate of 4° C. / min and a gas flow rate of 40 sccm, and the temperature was kept at 400° C. for 1 h, cooled to room temperature, and ground to obtain a biomass carbonization precursor;
[0049] (2) 0.5 g of the biomass carbonization precursor obtained in step (1) and 1.25 g of potassium hydroxide were shaken and mixed, ground at 70° C., and then evenly distributed in a nickel boat and placed in a high-temperature tube furnace. In an argon atmosphere, the temperature was raised to 700° C. at a heating rate of 4° C. / min and a gas flow rate of 40 sccm for reaction for 1 h. The mixture was cooled to room temperature, stirred and soaked in a 1 M hydrochloric acid solution for 8 h, washed with ultrapure water at 95° C. until neutral, and then added with ultrapure water for wet grinding at 400 r / min for 2 h to obtain a dispersion;
[0050] (3) The dispersion obtained in step (2) is washed, vacuum dried at 120° C. for 12 h, and then evenly distributed in a graphite crucible and placed in a high-temperature tube furnace. In an argon atmosphere, the temperature is increased to 500° C. at a heating rate of 4° C. / min and a gas flow rate of 40 sccm, and the temperature is maintained for 1 h. The dispersion is then cooled to room temperature to obtain highly stable biochar.
[0051] The method for preparing a supercapacitor electrode material comprises the following steps:
[0052] 80 parts of high-stable biochar, 5 parts of conductive carbon black and 5 parts of polyvinylidene fluoride binder were mixed evenly in N-methylpyrrolidone to obtain slurry; then the slurry was evenly coated on carbon-coated aluminum foil and rolled to obtain a compaction density of 0.615 g / cm -3 active electrode.
[0053] Test example
[0054] 1. Obtain a photograph of the volume change of the reconstructed biomass precursor material, i.e., the ramie precursor, during vacuum drying in Example 1, such as Figure 1 As shown. Among them, Figure 1 In the figure, a is the ramie precursor that has not been mechanically ground; b is the ramie precursor that has been mechanically ground.
[0055] Depend on Figure 1 It can be seen that in the absence of mechanical grinding, the ramie precursor after the evaporation of water molecules remains soft and loose, and the corresponding volume does not change significantly. After sufficient mechanical grinding, the fibrous ramie is transformed into a paste precursor. With the assistance of vacuum filtration, the disordered ramie precursor can be customized into a cylindrical block. Subsequently, the ramie block after the evaporation of water molecules shows obvious volume shrinkage, indicating that the disordered cellulose molecular chain is easier to densify.
[0056] 2. The molecular reconstruction mechanism of the ramie precursor obtained in Example 1 is as follows Figure 2 As shown. Among them, Figure 2 In the figure, a is a schematic diagram of the molecular reconstruction of the disordered ramie precursor; b is the functional relationship between the storage modulus, loss modulus and tangent increment and frequency; c is the SEM image of the disordered ramie precursor.
[0057] Depend on Figure 2It can be seen that natural ramie presents an ordered fibrous structure. Although the pre-embedded water molecules can enter the internal gaps of natural ramie, they cannot destroy its ordered structure. During the mechanical grinding process, the water molecules pre-embedded in the ramie can reduce the friction between the fibers, which is conducive to the formation of smaller particles and more disordered structures. From a microscopic perspective, the structure of the cellulose molecular chain also changes from long-range order to disorder, forming a dense three-dimensional hydrogen bond network. After the continuous evaporation of water molecules, the disordered ramie precursor continues to shrink and accumulate under the action of hydrogen bonds, forming a ramie precursor with high mechanical strength and high density. In addition, during the bending test, the storage modulus of the ramie precursor continued to increase with the increase of the vibration frequency, and no obvious cracks appeared. When the storage modulus of the ramie precursor increased to 3422MPa, the corresponding loss modulus was only 184MPa, indicating that it has excellent mechanical strength and deformation resistance. In addition, the change of loss factor with frequency also shows that the ramie precursor is an excellent rigid material. At the same time, it can be seen from the SEM image that the ramie precursor presents a rough and disordered network structure, which is conducive to improving its low-temperature carbonization efficiency and obtaining carbonized materials with strong consistency.
[0058] 3. The ramie precursor and natural ramie obtained in Example 1 were subjected to thermogravimetric analysis. The results are as follows: Figure 3 As shown. Among them, Figure 3 In the figure, a is the thermogravimetric curve; b is the differential thermal analysis curve.
[0059] Depend on Figure 3 It can be seen that the low-temperature pyrolysis process of the disordered ramie precursor is mainly divided into two stages: First, when the temperature is below 200°C, the weight loss of the precursor is mainly caused by the volatilization of water molecules. It is worth noting that the weight loss of natural ramie is greater, indicating that the process is also accompanied by the decomposition of small molecular organic matter. Second, when the pyrolysis temperature is between 200°C and 400°C, cellulose and hemicellulose begin to decompose, resulting in a significant increase in the weight loss of the disordered ramie precursor. The carbonization rate of the disordered ramie precursor is as high as 36.91%, indicating that the molecularly reconstructed ramie precursor is easier to convert into solid carbon during the pyrolysis process. By further comparing the relationship between the weight loss rate and temperature, the pyrolysis temperature of the disordered ramie precursor is significantly lower than that of natural ramie, indicating that the three-dimensional disordered network structure helps to improve its carbonization efficiency. In addition, the weight loss rate of the disordered ramie precursor is also relatively low, which is attributed to the thermal stability of the dense hydrogen bond network.
[0060] 4. Obtain the microscopic morphology of the highly stable biochar obtained in Example 1, such as Figure 4 As shown. Among them, Figure 4 In the figure, a is a SEM image; b is a low-resolution TEM image; c is a high-resolution TEM image.
[0061] Depend on Figure 4It can be seen that the highly stable ramie carbon can still maintain a complete bulk structure after KOH activation, indicating that the disordered ramie carbonization precursor has excellent structural stability during the high-temperature activation process. The low-resolution TEM image also confirmed that the highly stable ramie carbon is composed of a bulk structure without obvious pore structure, indicating that the carbon skeleton is relatively less corroded by the activator. The high-resolution TEM image shows that the highly stable ramie carbon exhibits an amorphous structure, which is attributed to its abundant micropores.
[0062] 5. The electrochemical performance of the supercapacitor obtained in Example 1 was tested. The results are as follows: Figure 5-6 As shown. Among them, Figure 5 In the figure, a is a photo of the soft-pack supercapacitor; b is the GCD curve with different loading amounts; c is the CV curve with different loading amounts; d is the GCD curve with different constant voltage time; e is the functional relationship between the voltage drop and the mass specific capacitance with the constant voltage time. Figure 6 In the figure, from bottom to top are the CV curves at different operating temperatures, photos of the soft-pack supercapacitor-driven LED light board and timer, and cycle life.
[0063] Depend on Figure 5 It can be seen that the soft-pack supercapacitor is composed of two identical rectangular electrodes with a length of 50 mm and a width of 44 mm. The high-load active electrode helps to evenly distribute the charge, reduce the voltage fluctuation during the charge and discharge process, and improve the working stability of the soft-pack supercapacitor. -2 Increased to 4.1 mg cm -2 When the soft-pack supercapacitor is still as high as 38.93F g -1 The mass specific capacitance of the supercapacitor decreased by only 5.85%, indicating that the high-stability ramie carbon electrode has excellent stability. The soft-pack supercapacitor consists of two identical rectangular electrodes with a length of 50 mm and a width of 44 mm. The high-load active electrode helps to evenly distribute the charge, reduce the voltage fluctuation during the charge and discharge process, and improve the working stability of the soft-pack supercapacitor. When the loading of the active electrode is increased from 1.4 mg cm -2 Increased to 4.1 mg cm -2 When the soft-pack supercapacitor is still as high as 38.93F g -1The mass specific capacitance of the soft-pack supercapacitor decreased by only 5.85%, indicating that the high-stability ramie carbon electrode has excellent stability. Appropriate constant voltage time helps to reduce the voltage drop. When the constant voltage time exceeds 10 seconds, the voltage drop of the soft-pack supercapacitor remains basically unchanged. In addition, the increase in constant voltage time has a relatively small effect on the mass specific capacitance of the soft-pack supercapacitor, indicating that the constant voltage process mainly promotes the uniform distribution of charge. When the operating temperature is 60°C, the supercapacitor can still maintain a regular rectangular shape and show relatively small capacity decay, indicating that the active electrode has excellent high-temperature stability. The soft-pack supercapacitor can light up the parallel LED light board and drive timer for a long time. Under the condition of a constant voltage time of 10 seconds, the high-stability ramie carbon-based soft-pack supercapacitor can still maintain 93.92% of the initial capacity after 10,000 cycles, indicating that appropriate constant voltage time helps to improve the long-term cycle stability of the device.
[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims
1. A method for preparing a reconstructed biomass precursor material with high mechanical strength and high density, characterized in that: The following steps are involved: The natural biomass is placed in ultrapure water, soaked at 85-95°C for 3-9 hours, washed and dried to obtain a biomass raw material; the biomass raw material is then placed in a polytetrafluoroethylene liner and ultrapure water is added, heated to 180-240°C and kept warm for 6 hours, cooled to room temperature, washed with ultrapure water, and then wet-milled with ultrapure water at 300-500r / min for 6 hours, and vacuum filtered and vacuum dried to obtain a reconstructed biomass precursor material with high mechanical strength and high density.
2. The method for preparing a reconstructed biomass precursor material with high mechanical strength and high density according to claim 1, characterized in that: The mass volume ratio of natural biomass and ultrapure water is 25g:1000mL; the mass volume ratio of biomass raw materials and ultrapure water is 1g:30mL.
3. The method for preparing a reconstructed biomass precursor material with high mechanical strength and high density according to claim 1, characterized in that: The natural biomass is ramie.
4. A reconstructed biomass precursor material with high mechanical strength and high density obtained by the preparation method of a reconstructed biomass precursor material with high mechanical strength and high density according to any one of claims 1 to 3.
5. A method for preparing highly stable biochar, characterized in that: The following steps are involved: (1) The reconstructed biomass precursor material with high mechanical strength and high density as claimed in claim 4 is crushed and sieved, and then the biomass precursor material is evenly distributed in a nickel boat and placed in a high-temperature tube furnace. In an argon atmosphere, the temperature is raised to 400° C. and kept for 1 hour, cooled to room temperature, and ground to obtain a biomass carbonization precursor; (2) mixing the biomass carbonization precursor obtained in step (1) and potassium hydroxide, grinding at 70° C., and then evenly distributing the mixture in a nickel boat and placing the mixture in a high-temperature tube furnace. In an argon atmosphere, heating the mixture to 700° C. for reaction for 1 h, cooling the mixture to room temperature, and placing the mixture in a hydrochloric acid solution for stirring and soaking, washing the mixture until it is neutral, and then adding ultrapure water for wet grinding at 200-400 r / min for 2 h to obtain a dispersion. (3) The dispersion obtained in step (2) is cleaned and vacuum dried, then evenly distributed in a graphite crucible and placed in a high-temperature tube furnace. In an argon atmosphere, the temperature is raised to 500° C. and kept for 1 hour, and then cooled to room temperature to obtain highly stable biochar.
6. The method for preparing highly stable biochar according to claim 5, characterized in that: In step (2), the mass ratio of the biomass carbonization precursor to potassium hydroxide is 0.5g:0.75-1.25g.
7. The method for preparing highly stable biochar according to claim 5, characterized in that: In step (2), the sample was immersed in a 1M hydrochloric acid solution with stirring for 8 hours, and then washed with ultrapure water at 95° C. until it became neutral.
8. The method for preparing highly stable biochar according to claim 5, characterized in that: In steps (1) to (3), when heating, the heating rate is 4°C / min and the gas flow rate is 40sccm.
9. Highly stable biochar obtained by the method for preparing highly stable biochar according to any one of claims 5 to 8.
10. Use of the highly stable biochar according to claim 9 in preparing supercapacitor electrode materials.