A method for converting thorny bamboo into multi-scale thin-layer graphite

Abstract

This invention discloses a method for converting bamboo into multi-scale thin-layer graphite, belonging to the field of high-value carbon nanomaterials derived from biomass. The method uses molten salt electrolysis as the graphitization means, bamboo-derived charcoal as the cathode, graphite or alloy as the anode, and molten salt as the electrolyte. The final product undergoes soaking followed by electrolysis, electrolysis during soaking, and washing to obtain bamboo-derived multi-scale thin-layer graphite with a thickness distribution of 10-20 nm, applicable to all bamboo-derived charcoals. This method demonstrates that molten salt electrolysis can control the size and thickness of graphite sheets based on bamboo-derived charcoal. Furthermore, the ability to control multi-scale thin-layer graphite through molten salt electrolysis can be extended to the field of biomass-derived charcoal, and its products have high commercial value in energy storage and conversion, thermal management of electronic equipment, and other fields.

Description

Technical Field

[0001] This invention relates to a method for converting thorny bamboo into multi-scale thin-layer graphite, belonging to the field of high-value carbon nanomaterials derived from biomass. Background Technology

[0002] Materials composed of thin-layer graphite exhibit superior mechanical strength compared to monolayer graphene due to the enhanced van der Waals forces between its layers. Simultaneously, it inherits the high electrical conductivity of monolayer graphene and further enhances conductivity by shortening the charge conduction path, thus providing superior performance for electronic devices. However, the preparation of such thin-layer graphite using biomass faces complex and challenging problems: existing processes, such as high-temperature graphitization followed by exfoliation at 3000℃ or catalytic graphitization, generally suffer from challenges such as high graphitization temperatures, insufficient graphitization degree and uniformity, difficulty in controlling morphology and size, and secondary catalyst removal.

[0003] As a widely available and inexpensive renewable biomass resource, the efficient conversion of thorny bamboo into thin-layer graphite is of great significance for realizing its high-value-added applications. Summary of the Invention

[0004] To address the shortcomings of the aforementioned technologies, this invention provides a method for converting thorny bamboo into multi-scale thin-layer graphite.

[0005] The solution adopted by the present invention to solve the above-mentioned technical problems is as follows: A method for converting thorny bamboo into multi-scale thin-layer graphite includes the following steps: using thorny bamboo-derived carbon as the cathode, graphite or alloy as the anode, and molten salt as the electrolyte, electrolysis is performed; after electrolysis, the resulting product is washed multiple times to complete the preparation, thereby obtaining the thorny bamboo-converted multi-scale thin-layer graphite.

[0006] Furthermore, the charcoal derived from thorny bamboo is selected from carbonized thorny bamboo, which includes at least one or a mixture of bamboo branches, bamboo walls, bamboo nodes, bamboo leaves, and bamboo rhizomes.

[0007] Furthermore, before carbonization, the bamboo undergoes a heat treatment at 50–250°C for 12–48 hours; during carbonization, the temperature is 400–1100°C for 2–48 hours. This pre-heat treatment removes adsorbed water, hemicellulose, and lignin degradation products from the bamboo, reducing violent reactions and structural damage during carbonization. It also promotes slow pyrolysis and cross-linking, forming a more developed porous structure, while reducing non-carbon content and tar formation, thereby increasing the fixed carbon yield and enhancing the conductivity and stability of the carbon material.

[0008] Furthermore, the carbonized bamboo is ball-milled to refine it into particles with diameters of 1-6µm, 6-15µm, 15-22µm, or 22-36µm.

[0009] Furthermore, the carbonized bamboo granules are pressed into sheets to serve as cathodes.

[0010] Furthermore, the molten salt participates in the reaction and acts as an electrolyte medium; its anion is Cl. - OH - CO3 2- One or more of them, whose cation is Mg 2+ Ca 2+ Zn 2+ Na + K + Li + One or more of them.

[0011] Furthermore, the temperature of the molten salt is 750~850℃.

[0012] Furthermore, the voltage during electrolysis is 1.5 ~ 3V, and the time is 2 ~ 12h.

[0013] Furthermore, electrolysis is divided into electrolysis after cathode immersion and electrolysis during cathode immersion. The main components of bamboo-derived charcoal are carbon and silicon dioxide. On the one hand, during electrolysis after immersion, silicon dioxide is preferentially dissolved, thereby exposing a larger specific surface area, which helps to promote the graphitization process of carbon materials. On the other hand, although electrolysis during immersion has little effect on the graphitization process of carbon materials, it has the technical advantage of shortening the preparation cycle.

[0014] Furthermore, the thickness distribution of multi-scale thin-layer graphite transformed from thorny bamboo is 10-20 nm.

[0015] Compared with existing technologies, this invention does not require templates or catalysts. Its scalable, low-cost, short-process and sustainable preparation method shows broad application prospects in the field of high-value-added bamboo-derived charcoal. The resulting products have high commercial value in the fields of energy storage materials, conductive and thermally conductive materials, etc. Attached Figure Description

[0016] Figure 1 The images shown are SEM images of bamboo before and after graphitization, and XRD images of bamboo after graphitization in Example 1.

[0017] Figure 2 This is a SEM image of the electrolysis products from Example 2.

[0018] Figure 3 This is a SEM image of the electrolysis product from Example 3.

[0019] Figure 4This is a SEM image of the electrolysis product of Example 4.

[0020] Figure 5 This is a SEM image of the electrolysis product from Example 5.

[0021] Figure 6 This is a SEM image of the electrolysis product of Example 11.

[0022] Figure 7 This is a SEM image of the electrolysis product of Example 12. Detailed Implementation

[0023] The following description is intended to help those skilled in the art understand the specific embodiments of the present invention. It should be noted that the scope of protection of the present invention is not limited to these specific embodiments. For those skilled in the art, all obvious modifications or inventive creations utilizing the inventive concept are protected within the spirit and scope of the invention as defined and determined by the claims.

[0024] This invention provides a first typical solution: electrolysis in cathode immersion. Using bamboo-derived charcoal as the cathode and graphite or a nickel-based alloy as the anode, electrolysis is performed in molten salt. After electrolysis, a thin layer of graphite is obtained after multiple washings.

[0025] This invention provides a second typical solution: electrolysis after cathode immersion. Using charcoal derived from bamboo as the cathode and graphite or a nickel-based alloy as the anode, electrolysis is performed in molten salt. After electrolysis, a thin layer of graphite is obtained after multiple washings. Example 1

[0026] A method for converting *Phyllostachys edulis* leaves into multi-scale thin-layer graphite involves drying *Phyllostachys edulis* leaves at 200℃ for 12 hours, carbonizing them at 800℃ for 12 hours, ball milling them into particles with a diameter of 1-6 µm, pressing them into sheets at 10 MPa to serve as the cathode, graphite as the anode, and using MgCO3-K2CO3 at 850℃ as the molten salt electrolyte. Electrolysis is performed at 1.9 V for 10 hours while the cathode is immersed in the solution. After electrolysis, the product is washed and dried to obtain the final product. XRD and SEM tests show that the *Phyllostachys edulis* leaves have been converted into thin-layer graphite. Figure 1 As shown in the figure, (a) is the SEM image of bamboo before graphitization, (b) is the SEM image after graphitization, and (c) is the XRD image after graphitization. Example 2

[0027] A method for converting *Phyllostachys edulis* leaves into multi-scale thin-layer graphite involves drying *Phyllostachys edulis* leaves at 200℃ for 12 hours, followed by carbonization at 800℃ for 12 hours. The resulting particles are then ball-milled into finer particles with a diameter of 6-15 µm, pressed into sheets at 10 MPa to serve as the cathode, and graphite as the anode. Na₂CO₃-K₂CO₃ at 800℃ is used as the molten salt electrolyte. Electrolysis is performed at 1.9 V for 12 hours while the cathode is immersed in the solution. After electrolysis, the product is washed and dried to obtain the final product. Tests show that the *Phyllostachys edulis* leaves have been converted into thin-layer graphite. Figure 2 As shown. Example 3

[0028] A method for converting thorny bamboo into multi-scale thin-layer graphite involves drying thorny bamboo branches at 200℃ for 12 hours, followed by carbonization at 800℃ for 12 hours. The resulting material is then ball-milled into particles with a diameter of 15-22 µm, pressed into sheets at 10 MPa to serve as the cathode, and a nickel-based alloy as the anode. Na₂CO₃-K₂CO₃ at 850℃ is used as the molten salt electrolyte. Electrolysis at 2.1V for 10 hours is performed while the cathode is immersed in the solution. After electrolysis, the product is washed and dried to obtain the final product. Tests show that the thorny bamboo branches have been converted into thin-layer graphite. Figure 3 As shown. Example 4

[0029] A method for converting thorny bamboo into multi-scale thin-layer graphite involves drying thorny bamboo branches at 200℃ for 12 hours, followed by carbonization at 800℃ for 12 hours. The resulting material is then ball-milled into particles with a diameter of 22-36 µm, pressed into sheets at 10 MPa to serve as the cathode, and graphite as the anode. Na₂CO₃-K₂CO₃ at 850℃ is used as the molten salt electrolyte. Electrolysis is performed at 2.1V for 12 hours while the cathode is immersed. After electrolysis, the product is washed and dried to obtain the final product. Tests show that the thorny bamboo branches have been converted into thin-layer graphite. Figure 4 As shown. Example 5

[0030] A method for converting thorny bamboo into multi-scale thin-layer graphite involves drying thorny bamboo nodes at 200℃ for 12 hours, followed by carbonization at 800℃ for 12 hours. The resulting particles are then ball-milled into finer particles with a diameter of 1-6 µm, pressed into sheets at 10 MPa to serve as the cathode, a nickel-based alloy as the anode, and MgCl2-K2CO3 at 750℃ as the molten salt electrolyte. After immersion in the cathode for 2 hours, electrolysis is performed at 2.0V for 8 hours. The product is then washed and dried after electrolysis. Tests show that the thorny bamboo nodes have been converted into thin-layer graphite. Figure 5 As shown. Example 6

[0031] A method for converting thorny bamboo into multi-scale thin-layer graphite involves baking thorny bamboo nodes at 200℃ for 12 hours, followed by carbonization at 800℃ for 12 hours, then ball milling to refine the particles into 6-15µm particles, and finally pressing them into sheets at 10MPa to serve as the cathode, with graphite as the anode, and Na2CO3-K2CO3 at 850℃ as the molten salt electrolyte. After soaking in the cathode for 3 hours, electrolysis is performed at 2.0V for 10 hours. After electrolysis, the product is washed and dried to obtain the final product. Tests show that the thorny bamboo nodes have been converted into thin-layer graphite. Example 7

[0032] A method for converting thorny bamboo into multi-scale thin-layer graphite involves drying thorny bamboo nodes at 200℃ for 12 hours, followed by carbonization at 800℃ for 12 hours. The resulting particles are then ball-milled to a particle size of 15-22 µm and pressed into sheets at 10 MPa to serve as the cathode. Graphite is used as the anode, and MgCl2-K2CO3 at 750℃ is used as the molten salt electrolyte. After soaking in the cathode for 5 hours, electrolysis is performed at 2.0V for 10 hours. The product is then washed and dried after electrolysis. Tests show that the thorny bamboo nodes have been converted into thin-layer graphite. Example 8

[0033] A method for converting thorny bamboo into multi-scale thin-layer graphite involves baking thorny bamboo nodes at 200℃ for 12 hours, followed by carbonization at 800℃ for 12 hours, then ball milling to refine the particles into 22-36µm particles, pressing them into sheets at 10MPa to serve as the cathode, using a nickel-based alloy as the anode, and MgCl2-K2CO3 at 750℃ as the molten salt electrolyte. After soaking in the cathode for 6 hours, electrolysis at 2.1V for 10 hours is performed. The product is then washed and dried after electrolysis. Tests show that the thorny bamboo nodes have been converted into thin-layer graphite. Example 9

[0034] A method for converting thorny bamboo into multi-scale thin-layer graphite involves baking thorny bamboo nodes at 200℃ for 12 hours, followed by carbonization at 800℃ for 12 hours, then ball milling to refine the particles into 6-15µm particles, and finally pressing them into sheets at 10MPa to serve as the cathode. Graphite is used as the anode, and Na₂CO₃-K₂CO₃ is used as the molten salt electrolyte at 800℃. After soaking in the cathode for 10 hours, electrolysis is performed at 2.1V for 10 hours. After electrolysis, the product is washed and dried to obtain the final product. Tests show that the thorny bamboo nodes have been converted into thin-layer graphite. Example 10

[0035] A method for converting thorny bamboo into multi-scale thin-layer graphite involves baking thorny bamboo nodes at 200℃ for 12 hours, followed by carbonization at 800℃ for 12 hours, then ball milling to refine the particles into 15-22µm particles, and finally pressing them into sheets at 10MPa to serve as the cathode. Graphite is used as the anode, and Na₂CO₃-CaCO₃ is used as the molten salt electrolyte at 800℃. After soaking in the cathode for 5 hours, electrolysis is performed at 2.0V for 10 hours. After electrolysis, the product is washed and dried to obtain the final product. Tests show that the thorny bamboo nodes have been converted into thin-layer graphite. Example 11

[0036] A method for converting thorny bamboo into multi-scale thin-layer graphite involves baking thorny bamboo nodes at 200℃ for 12 hours, followed by carbonization at 800℃ for 12 hours, then ball milling to refine the particles into 6-15µm particles, and finally pressing them into sheets at 10MPa to serve as the cathode. Graphite is used as the anode, and CaCl2-CaCO3 is used as the molten salt electrolyte at 800℃. After soaking in the cathode for 4 hours, electrolysis is performed at 2.2V for 10 hours. After electrolysis, the product is washed and dried to obtain the final product. Tests show that the thorny bamboo nodes have been converted into thin-layer graphite. Figure 6 As shown. Example 12

[0037] A method for converting thorny bamboo into multi-scale thin-layer graphite involves baking thorny bamboo nodes at 200℃ for 12 hours, carbonizing them at 800℃ for 12 hours, ball milling them into particles with a diameter of 6-15µm, and then pressing them into sheets at 10MPa to serve as the cathode. Graphite is used as the anode, and Na₂CO₃-CaCO₃ is used as the molten salt electrolyte at 750℃. After soaking in the cathode for 2 hours, electrolysis is performed at 2.0V for 10 hours. After electrolysis, the product is washed and dried to obtain the final product. Tests show that the thorny bamboo nodes have been converted into thin-layer graphite. Figure 7 As shown. Example 13

[0038] A method for converting thorny bamboo into multi-scale thin-layer graphite involves drying thorny bamboo branches at 50℃ for 48 hours, carbonizing them at 1100℃ for 2 hours, ball milling them into particles with a diameter of 1-6µm, pressing them into sheets at 10MPa to serve as the cathode, using a nickel-based alloy as the anode, and MgCO3-K2CO3 at 800℃ as the molten salt electrolyte. Electrolysis is performed at 1.5V for 5 hours while the cathode is immersed in the solution. After electrolysis, the product is washed and dried to obtain the final product. Tests show that the thorny bamboo branches have been converted into thin-layer graphite. Example 14

[0039] A method for converting thorny bamboo into multi-scale thin-layer graphite involves baking the bamboo wall at 100℃ for 24 hours, then carbonizing it at 400℃ for 48 hours, followed by ball milling to refine it into particles with a diameter of 15-22µm. These particles are then pressed into sheets at 10 MPa to serve as the cathode, with graphite as the anode, and Na₂CO₃-K₂CO₃ at 750℃ as the molten salt electrolyte. Electrolysis is performed at 3.0V for 2 hours while the cathode is immersed in the solution. After electrolysis, the product is washed and dried to obtain the final product. Tests show that the thorny bamboo wall has been converted into thin-layer graphite. Example 15

[0040] A method for converting thorny bamboo into multi-scale thin-layer graphite involves drying the bamboo rhizomes at 250℃ for 12 hours, then carbonizing them at 750℃ for 30 hours. The resulting particles are then ball-milled to a particle size of 6-15 µm and pressed into sheets at 10 MPa to serve as the cathode. Graphite is used as the anode, and MgCl2-K2CO3 at 850℃ is used as the molten salt electrolyte. After soaking in the cathode for 8 hours, electrolysis is performed at 2.5V for 5 hours. The product is then washed and dried after electrolysis. Tests show that the thorny bamboo rhizomes have been converted into thin-layer graphite.

[0041] Finally, it should be noted that the above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit the scope thereof. Those skilled in the art can make modifications or equivalent substitutions without departing from the scope of the claims.

Claims

1. A method for converting thorny bamboo into multi-scale thin-layer graphite, characterized in that, Includes the following steps: Using charcoal derived from thorny bamboo as the cathode, graphite or alloy as the anode, and molten salt as the electrolyte, electrolysis is performed. After electrolysis, the resulting product is washed multiple times to complete the preparation, thus obtaining the thorny bamboo-derived multi-scale thin-layer graphite.

2. The method for converting thorny bamboo into multi-scale thin-layer graphite according to claim 1, characterized in that, The charcoal derived from thorny bamboo is selected from carbonized thorny bamboo, which includes at least one or a mixture of bamboo branches, bamboo walls, bamboo nodes, bamboo leaves, and bamboo rhizomes.

3. The method for converting thorny bamboo into multi-scale thin-layer graphite according to claim 2, characterized in that, Before carbonization, the bamboo is subjected to heat treatment at a temperature of 50~250℃ for 12~48h; during carbonization, the temperature is 400~1100℃ and the time is 2~48h.

4. The method for converting thorny bamboo into multi-scale thin-layer graphite according to claim 3, characterized in that, The carbonized bamboo is then ball-milled to refine it into particles with diameters of 1-6µm, 6-15µm, 15-22µm, or 22-36µm.

5. The method for converting thorny bamboo into multi-scale thin-layer graphite according to claim 4, characterized in that, Carbonized bamboo granules are pressed into sheets to serve as cathodes.

6. The method for converting thorny bamboo into multi-scale thin-layer graphite according to claim 1, characterized in that, Molten salts participate in the reaction and act as electrolyte media; their anion is Cl. - OH - CO3 2- One or more of them, whose cation is Mg 2+ Ca 2 + Zn 2+ Na + K + Li + One or more of them.

7. The method for converting thorny bamboo into multi-scale thin-layer graphite according to claim 6, characterized in that, The temperature of the molten salt is 750~850℃.

8. The method for converting thorny bamboo into multi-scale thin-layer graphite according to claim 1, characterized in that, The voltage during electrolysis is 1.5 ~ 3V, and the time is 2 ~ 12h.

9. The method for converting thorny bamboo into multi-scale thin-layer graphite according to claim 1, characterized in that, Electrolysis is divided into electrolysis after cathode immersion and electrolysis during cathode immersion.

10. The method for converting thorny bamboo into multi-scale thin-layer graphite according to claim 1, characterized in that, The thickness distribution of multi-scale thin-layer graphite transformed from thorny bamboo is 10-20 nm.

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